Weller WTCPT tip not hot enough
George Orwell
PTA7 700 degrees F. tip. It's 15 years old and hasn't seen much action. I
was using it a lot 3 years ago but for the past 2 years it's been sitting
cold in the garage.
The past couple times I've used it lately the tip just didn't seem to get
as hot as I remember. You know how it is with equipment you use for a long
time, you get to know the behavior and what's normal. When I put the
heated tip against the sponge, I barely get much of a sizzle. Solder barely
melts but does melt, just barely though.
I've gone through the troubleshooting guide Weller provides for this
station, all appears normal. I have 27.3VAC from the power unit. Heater
element reads 12.9 ohms. The "magnastat" opens and closes when the tip is
inserted and removed. Unfortunately the guide doesn't cover a warm tip,
only one that's stone cold or too hot. I don't know what else to check.
I can hear the tip cycling when I turn on the base. It just seems that the
heater doesn't stay on long enough like it used to. Do the tips somehow
lose their temperature calibration? Is it time for a new soldering
station? Any opinions on the WESD51?
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Dave Platt
George Orwell <nob...@mixmaster.it> wrote:
>I can hear the tip cycling when I turn on the base. It just seems that the
>heater doesn't stay on long enough like it used to. Do the tips somehow
>lose their temperature calibration? Is it time for a new soldering
>station? Any opinions on the WESD51?
The temperature calibration is via the ferromagnetic slug at the back
end of each individual tip. I suppose it's possible that the alloy in
the slug can "drift" its transition temperature with time, although I
haven't noticed this myself.
Try removing your current tip and replacing it with another of the
appropriate tip shape and temperature range (they come in 600, 700,
and 800 degree Farenheit ratings) and see if this resolves the
problem. The tips themselves are not expensive... U.S. dealers seem
to have them for around $5 in most shapes.
I suppose it's possible that the heater in the handle is giving out,
or that oxidation on contacts somewhere is preventing adequate current
flow to re-heat the iron.
--
Dave Platt <dpl...@radagast.org> AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!
Jeff Liebermann
<nob...@mixmaster.it> wrote:
>I have a Weller WTCPT soldering station with the stock TC201T handle and
>PTA7 700 degrees F. tip. It's 15 years old and hasn't seen much action. I
>was using it a lot 3 years ago but for the past 2 years it's been sitting
>cold in the garage.
>
>The past couple times I've used it lately the tip just didn't seem to get
>as hot as I remember. You know how it is with equipment you use for a long
>time, you get to know the behavior and what's normal. When I put the
>heated tip against the sponge, I barely get much of a sizzle. Solder barely
>melts but does melt, just barely though.
>
>I've gone through the troubleshooting guide Weller provides for this
>station, all appears normal. I have 27.3VAC from the power unit. Heater
>element reads 12.9 ohms. The "magnastat" opens and closes when the tip is
>inserted and removed. Unfortunately the guide doesn't cover a warm tip,
>only one that's stone cold or too hot. I don't know what else to check.
>
>I can hear the tip cycling when I turn on the base. It just seems that the
>heater doesn't stay on long enough like it used to. Do the tips somehow
>lose their temperature calibration? Is it time for a new soldering
>station? Any opinions on the WESD51?
Nice mystery. I have about 8 Weller soldering stations with exactly
the same configuration. I've never seen that problem. It's usually
either stone cold, or seriously overheating.
I assume that the thermostat cannot be heard clicking when the iron is
running luke warm.
Maybe a bit of logic might help. The voltage and resistance that you
measured are normal. If there were any excessive resistance in the
heater part of the system, such as bad thermostat contacts, bad cord,
or bad twist lock connections in the handle, these would heat
sufficiently to create noticable damage. Only the high resistance in
the xformer area in the base could cause low output, yet still read
the correct voltage. It might also be a high resistance thermal fuse
or high resistance on/off switch.
Perhaps it would be useful to measure the resistances in the base.
Ummm... unplug the soldering iron first. When stone cold, I measure
1.5 ohms across the 117VAC power plug and 1.5 ohms across the xformer
output pins. My guess(tm) is that you'll find one or the other with a
quite different resistance.
As for a replacement, I have enough parts to build and/or repair
perhaps 10 more WTCPT soldering stations, so I've never needed to
consider an alternative. If I need one, I just build one out of junk.
Unfortunately, they'er not particularly reliable and require constant
thermostat contact cleaning. I've also had heating elements die,
thermostat movement jam from corrosion, cords fuse internally, and one
xformer short and melt. If you buy something new, buy one that
doesn't have any moving parts.
--
Jeff Liebermann je...@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
Jamie
Jeff Liebermann
<jamie_ka1lpa_not_v...@charter.net> wrote:
>Lead Free Solder in use?
Ummm.... He said:
"When I put the heated tip against the sponge, I barely get
much of a sizzle. Solder barely melts but does melt, just
barely though."
If it doesn't boil water, it's not going to melt solder.
I use a PTA7 (370C) tip with the evil lead-free solder. It's not the
best, but it sorta works. A PTA8 (430C) tip works much better but
I've been burning up a tip every 3 months or so.
Jim Adney
<nob...@mixmaster.it> wrote:
>I have a Weller WTCPT soldering station with the stock TC201T handle and
>PTA7 700 degrees F. tip. It's 15 years old and hasn't seen much action. I
>was using it a lot 3 years ago but for the past 2 years it's been sitting
>cold in the garage.
>
>The past couple times I've used it lately the tip just didn't seem to get
>as hot as I remember. You know how it is with equipment you use for a long
>time, you get to know the behavior and what's normal. When I put the
>heated tip against the sponge, I barely get much of a sizzle. Solder barely
>melts but does melt, just barely though.
These are great stations, but many of them have one common flaw: One
of the crimped female pins in the base, where you plug in the iron, is
often crimped onto solid wire, and that connection will go bad within
about a year of reasonable use. Once that connection goes bad, it will
heat up and destroy the plastic connector body, so the best thing to
do is to fix it before it gives problems. When we used to buy these
new, I would fix this in new units before they were ever turned on.
If you have a large selection of pin remover tools you may have one
that will work on these, but I've often had to make do with a bit of
rolled up soda can alum sheet. It's tedious, but you really only HAVE
to remove the one solid wire. The stranded crimps will be fine.
Once you get the pin out, just solder it and put it back.
My guess is that this is what's happened to your station. The power is
being split between the heater and the connector. It's also possible
that the switch in the iron handle is going bad. That certainly
happens, but usually only after a lot of use.
The Magnestat control depends on the Curie temp of the alloy in the
little slug at the end of the tip. That will never change.
It's a little confusing that you say you can hear the Magnestat
control switching back and forth. This is normal, but it should only
happen if the tip is reaching it's 700 F Curie temp. This one
observaion makes me wonder if you're just not remembering how it used
to work.
Even if it doesn't happen to be the problem right now, it's still a
good idea to solder that pin, because it will save you headaches down
the road.
-
-----------------------------------------------
Jim Adney jad...@vwtype3.org
Madison, WI 53711 USA
-----------------------------------------------
George Orwell
wrote:
>I use a PTA7 (370C) tip with the evil lead-free solder. It's not the
>best, but it sorta works. A PTA8 (430C) tip works much better but
>I've been burning up a tip every 3 months or so.
I just measured the tip temperature with a temperature probe that came with
an inexpensive meter I bought a few years ago. The package claims the
probe can measure up to 1200 degrees F. so I pressed the heated tip against
the probe tip sitting on top of a piece of wood. The tip measured 570
degrees F. max. The thing just seems to be cycling more than I would
expect.
I'll buy a new tip at Frys tomorrow and see if it works better. I just
know that something isn't normal with the station. There's nothing more
frustrating than trying to unsolder a component only to have the soldering
iron flake out at the worst moment. I solder and repair old tube
televisions and radios as well as Pentium 4 motherboards, mostly leaking
capacitors and cold solder joints in power supplies.
I'm using Kester Kwik-Draw Rosin Core 60% Tin/40% Lead, .053" diameter.
What does it mean to burn up a tip? If there's no heating element in these
tips how does it burn up?
Jeff Liebermann
<nob...@mixmaster.it> wrote:
>The thing just seems to be cycling more than I would
>expect.
Ok, the thermostat is cycling. I've been assuming that it was NOT
cycling.
If the temperature is as low as you measure, then the primary
temperature determining element is the magnetic in the tip. If it's
off for some reason, you will get different temperatures. I've had
the base of the tip (the shiny part with the number "7" stamped into
it) fall off. I can replace it, but the temperature regulation is
rather erratic.
>I'll buy a new tip at Frys tomorrow and see if it works better.
That will probably solve the problem. You might want to buy a larger
blade tip for dealing with physically larger components.
>I'm using Kester Kwik-Draw Rosin Core 60% Tin/40% Lead, .053" diameter.
I prefer 63/37 but 60/40 is good enough. It should work just fine
with the 700F tip.
>What does it mean to burn up a tip? If there's no heating element in these
>tips how does it burn up?
The outer plating disappears. The part that needs to be cleaned and
tinned burns up (oxidizes) if left hot and sitting around for 10+
hours per day. Eventually, I can't tin it any more. The solder just
doesn't stick. I've tried various potions for re-tinning the tips
(Kester Ultrapure Tip Tinner), and Sal Ammonica (a flux), but have had
no success in reviving the tips. Only the 800F tips seem to have the
problem as the 700F tips last much longer. I would post a photo but I
can't find a dead tip. A clue is that the tip slowly turns black
instead of the usual shiny (tinned) silver color.
Samuel M. Goldwasser
> I have a Weller WTCPT soldering station with the stock TC201T handle and
> PTA7 700 degrees F. tip. It's 15 years old and hasn't seen much action. I
> was using it a lot 3 years ago but for the past 2 years it's been sitting
> cold in the garage.
>
> The past couple times I've used it lately the tip just didn't seem to get
> as hot as I remember. You know how it is with equipment you use for a long
> time, you get to know the behavior and what's normal. When I put the
> heated tip against the sponge, I barely get much of a sizzle. Solder barely
> melts but does melt, just barely though.
>
> I've gone through the troubleshooting guide Weller provides for this
> station, all appears normal. I have 27.3VAC from the power unit. Heater
> element reads 12.9 ohms. The "magnastat" opens and closes when the tip is
> inserted and removed. Unfortunately the guide doesn't cover a warm tip,
> only one that's stone cold or too hot. I don't know what else to check.
>
> I can hear the tip cycling when I turn on the base. It just seems that the
> heater doesn't stay on long enough like it used to. Do the tips somehow
> lose their temperature calibration? Is it time for a new soldering
> station? Any opinions on the WESD51?
You say you "can hear the tip cycling". If that's the case, it would seem
that there can't be anything wrong with the electrical parts. The tip
cycles based on reaching the curie temperature of the magnet.
Have you tried a new tip?
--
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Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
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Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.
Samuel M. Goldwasser
> What does it mean to burn up a tip? If there's no heating element in these
> tips how does it burn up?
I assume he means the plating gets destroyed so it doesn't tin properly
anymore. I have a pile like that. :( :)
N_Cook
news:a7fbd640edfa2a3b...@mixmaster.it...
Remember to replace the shroud that screws on and retains the tip, it is
part of the magnetic "circuit" and if absent causes that sort of problem.
Also if you're careful , ie parallel jaw pliers, you can pull off the
magnastat of a worn tip and change the temp on another good but wrong temp
tip.
--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/
William Sommerwerck
Arfa Daily
"Jeff Liebermann" <je...@cruzio.com> wrote in message
news:r3v1b450a0n1dap2t...@4ax.com...
I used to find that my 700 deg tips lasted for months with my Weller PTC on
10-12 hours a day, but recently, I've found them to be burning out in just a
few weeks. At first, I thought it might be that the Magnastat was seized
shut, overheating the tip, but it is clicking on and off quite normally.
Unless Weller have done something to change the tip plating, I can't really
think of any other reason that this is occuring. This iron has been the
workhorse of my workshop for years, and like the OP on this thread, I am
extremely familiar with all aspects of its normal functioning.
About the only other possibility that I can think of is that I am doing more
lead-free work now than I was, and just maybe, the more aggressive fluxes
that are incorporated in this hateful stuff, are attacking the tip plating.
I'm actually still not doing anything like as much lead-free soldering as I
am leaded, but I guess that after making lead-free joints, solder is still
sitting on the tip perhaps for hours at a time. Another slight possibility
is that a mix of leaded and lead-free sitting on the tip, is causing
problems for the plating. The only reason that I say this, is that when I
was researching an article that I wrote on lead-free, I spoke with an expert
on the subject, and one of his papers stated quite clearly that leaded and
lead-free should not be mixed in the same joint, as it was likely to result
in long term compromise of the joint integrity. I'm not sufficiently versed
in metalurgy or chemistry to understand why this might be, but maybe a
factor ?
Arfa
Jeff Liebermann
<arfa....@ntlworld.com> wrote:
>I used to find that my 700 deg tips lasted for months with my Weller PTC on
>10-12 hours a day, but recently, I've found them to be burning out in just a
>few weeks.
I had a similar problem a few years ago. At the time, I had 3 Weller
WTCPT irons deployed. Two at my house and one at the office. The one
in my shop kept eating tips. They would slowly turn black and refuse
to tin. All my tips came from the same batch so it wasn't the tip. I
bought about 25 of these stations plus parts at an auction perhaps 20
years ago. I rotated the 3 irons between locations and found that the
problem remained with the shop location. Then, I realized that the
one thing that I was doing in the shop, but not at the other
locations, was using the iron to melt plastic parts. I tended to use
it for plastic welding and drilling. I would clean and tin the tip
immediately afterwards, but apparently the damage was already done.
I'm not sure of the exact mechanism, but something in the plastic
might be removing or trashing the plating on the tip.
>About the only other possibility that I can think of is that I am doing more
>lead-free work now than I was, and just maybe, the more aggressive fluxes
>that are incorporated in this hateful stuff, are attacking the tip plating.
Most of the rework I do in the office is with the evil lead-free
solder. If the board used lead-free, my resoldering should use the
same. I have both types of solders and use them as required by the
type of board. I haven't seen any such tip problems with lead-free.
>I spoke with an expert
>on the subject, and one of his papers stated quite clearly that leaded and
>lead-free should not be mixed in the same joint, as it was likely to result
>in long term compromise of the joint integrity. I'm not sufficiently versed
>in metalurgy or chemistry to understand why this might be, but maybe a
>factor ?
I dunno. I've been told the same thing. That's why I have two rolls
of solder at each workstation. I don't really understand the failure
mechanism when mixing solder and flux types. However, now that you
mention it, I have been replacing tips at a faster rate since I've
started using some lead-free solders.
I did some Googling for soldering iron tips that were specifically
designed for lead-free soldering. I found several, but none that
bothered to mention the difference between ordinary and lead-free
tips. I'll guess that it's pure marketing and that there's no real
difference in construction, other than operating at about 50F higher
in temperature.
Jeff Liebermann
<grizzle...@comcast.net> wrote:
>Does this unit have a temperature-calibration pot?
No. The Weller WTCPT has no controls or adjustments. The primary
temperature determining component is the curie point of the magnet in
the tip. At low temperatures, the magnet holds a piston, which pulls
a pair of relay type contacts closed, which then runs the heating
element. When the tip temperature reaches the curie point, the
magnetism disappears, opening the contacts. There's nothing in the
contact assembly that would affect the temperature, except perhaps if
the piston were stuck. That's unlikely because of the huge clearances
involved. If it's cycling, then only the tip can affect the
temperature threshold.
Weller manuals:
<http://bama.sbc.edu/weller.htm>
WTCPT manual:
<ftp://bama.sbc.edu/downloads/weller/wtcpt/> (215KB)
See section on "Principle of Operation".
Dave Platt
Jeff Liebermann <je...@cruzio.com> wrote:
> Then, I realized that the
>one thing that I was doing in the shop, but not at the other
>locations, was using the iron to melt plastic parts. I tended to use
>it for plastic welding and drilling. I would clean and tin the tip
>immediately afterwards, but apparently the damage was already done.
>I'm not sure of the exact mechanism, but something in the plastic
>might be removing or trashing the plating on the tip.
My guess is that the breakdown of the plastic was releasing a
halogen-rich vapor, either from the plastic itself (e.g. PVC is
polyvinyl chloride and can release chlorine-rich combustion products)
or from a fire retardant (often chlorine- or bromine-based).
It would not surprise me if such halogen-rich compounds would be
chemically-active enough to corrode the iron plating on a soldering
tip, and eventually expose the underlying copper.
George Orwell
wrote:
>>I'll buy a new tip at Frys tomorrow and see if it works better.
>
>That will probably solve the problem. You might want to buy a larger
>blade tip for dealing with physically larger components.
Just installed and tested a new PTA7 tip and it works fine. The
temperature as measured by my probe reads 735 degrees F. The tip was Made
in Mexico, July 2007, Lead Free, RoHS compliant. The tip I had been using
was 15 years old so maybe it was time for a new one. I also picked up a
PTA8 tip but that's still sealed in the bag.
Eeyore
George Orwell wrote:
> I have a Weller WTCPT soldering station with the stock TC201T handle and
> PTA7 700 degrees F. tip.
I prefer 800 degrees. Always have done. Esp with small tips. The idea is to get
the soldering done as fast as quickly, not leave the joint cooking until the
solder finally melts.
I've seen plenty of 'cold' / 'dry' joints arising from the use of 700F tips. I
even told the manufacturing dept of a certain company to change to 800F tips
for a certain process but they moaned that 'the tips wear out faster'. So the
returns rate went up again Bloody idiots.
Graham
Eeyore
"Samuel M. Goldwasser" wrote:
> George Orwell <nob...@mixmaster.it> writes:
>
> > I have a Weller WTCPT soldering station with the stock TC201T handle and
> > PTA7 700 degrees F. tip. It's 15 years old and hasn't seen much action. I
> > was using it a lot 3 years ago but for the past 2 years it's been sitting
> > cold in the garage.
> >
> > The past couple times I've used it lately the tip just didn't seem to get
> > as hot as I remember. You know how it is with equipment you use for a long
> > time, you get to know the behavior and what's normal. When I put the
> > heated tip against the sponge, I barely get much of a sizzle. Solder barely
> > melts but does melt, just barely though.
> >
> > I've gone through the troubleshooting guide Weller provides for this
> > station, all appears normal. I have 27.3VAC from the power unit. Heater
> > element reads 12.9 ohms. The "magnastat" opens and closes when the tip is
> > inserted and removed. Unfortunately the guide doesn't cover a warm tip,
> > only one that's stone cold or too hot. I don't know what else to check.
> >
> > I can hear the tip cycling when I turn on the base. It just seems that the
> > heater doesn't stay on long enough like it used to. Do the tips somehow
> > lose their temperature calibration? Is it time for a new soldering
> > station? Any opinions on the WESD51?
>
> You say you "can hear the tip cycling". If that's the case, it would seem
> that there can't be anything wrong with the electrical parts. The tip
> cycles based on reaching the curie temperature of the magnet.
>
> Have you tried a new tip?
Well there is the issue of lead-free solder too which requires a 50C (90F) or so
hotter tip.
Graham
Eeyore
George Orwell wrote:
> I have a Weller WTCPT soldering station with the stock TC201T handle and
> PTA7 700 degrees F. tip. It's 15 years old and hasn't seen much action. I
> was using it a lot 3 years ago but for the past 2 years it's been sitting
> cold in the garage.
>
> The past couple times I've used it lately the tip just didn't seem to get
> as hot as I remember. You know how it is with equipment you use for a long
> time, you get to know the behavior and what's normal. When I put the
> heated tip against the sponge, I barely get much of a sizzle. Solder barely
> melts but does melt, just barely though.
Your reply address suggests you are in Italy. But why are you using dizum ?
Are you unaware of the extra temperature required to melt the lead-free solder
now mandated in the EU ?
Graha,
Jamie
> In article <8m63b4lfhlmu0u8mg...@4ax.com>,
> Jeff Liebermann <je...@cruzio.com> wrote:
>
>
>> Then, I realized that the
>>one thing that I was doing in the shop, but not at the other
>>locations, was using the iron to melt plastic parts. I tended to use
>>it for plastic welding and drilling. I would clean and tin the tip
>>immediately afterwards, but apparently the damage was already done.
>>I'm not sure of the exact mechanism, but something in the plastic
>>might be removing or trashing the plating on the tip.
>
>
> My guess is that the breakdown of the plastic was releasing a
> halogen-rich vapor, either from the plastic itself (e.g. PVC is
> polyvinyl chloride and can release chlorine-rich combustion products)
> or from a fire retardant (often chlorine- or bromine-based).
>
> It would not surprise me if such halogen-rich compounds would be
> chemically-active enough to corrode the iron plating on a soldering
> tip, and eventually expose the underlying copper.
>
Which is why they formulate compounds used for conductor to not do that
these days.
My place of employment uses non halogen compounds and low if no
chlorine type chemicals in the plastics used in common cable and
wire products.
I've seen many times copper wire eroded inside just from its own
PVC insulation due to older chemical mixes which we don't use any more.
--
http://webpages.charter.net/jamie_5"
Arfa Daily
"Eeyore" <rabbitsfriend...@hotmail.com> wrote in message
news:48B1CF3E...@hotmail.com...
Just to be clear though, only mandated for items placed on the market after
June 2006, and which don't have a waiver. Items manufactured prior to that
using conventional leaded solder, can continue to be repaired / reworked /
modified with leaded solder and non RoHS compliant components. New items for
non commercial i.e. amateur use, can still be constructed in whatever
component and solder technology you like.
Arfa
Eeyore
Arfa Daily wrote:
> "Eeyore" wrote
> > George Orwell wrote:
> >
> >> I have a Weller WTCPT soldering station with the stock TC201T handle and
> >> PTA7 700 degrees F. tip. It's 15 years old and hasn't seen much action.
> >> I was using it a lot 3 years ago but for the past 2 years it's been sitting
>
> >> cold in the garage.
> >>
> >> The past couple times I've used it lately the tip just didn't seem to get
> >> as hot as I remember. You know how it is with equipment you use for a
> >> long time, you get to know the behavior and what's normal. When I put the
> >> heated tip against the sponge, I barely get much of a sizzle. Solder
> >> barely melts but does melt, just barely though.
> >
> > Your reply address suggests you are in Italy. But why are you using dizum
> > ?
> >
> > Are you unaware of the extra temperature required to melt the lead-free
> > solder now mandated in the EU ?
>
>
> Just to be clear though, only mandated for items placed on the market after
> June 2006, and which don't have a waiver. Items manufactured prior to that
> using conventional leaded solder, can continue to be repaired / reworked /
> modified with leaded solder and non RoHS compliant components. New items for
> non commercial i.e. amateur use, can still be constructed in whatever
> component and solder technology you like.
Absolutely, although we have no idea what he's soldering. I still prefer 800F
tips for quick neat soldering.
Graham
Arfa Daily
I still use 700s because of the problem of 800s burning out quicker when
left idling all day, but I might try 800s again, if only for the improvement
on the dreaded lead-free. I only said about the RoHS regs because there will
be a lot of people reading the thread, who perhaps wouldn't understand the
implications of the legislation. A while back, there was a lot of confusion
and misconceptions about what it meant to the service industry, not helped
by a couple of trade bulletins on the subject which were put out by at least
one major Jap manufacturer, and one soldering equipment manufacturer, and
which gave entirely the wrong impression. It was this which prompted me to
write the article.
Arfa
Jim Adney
<rabbitsfriend...@hotmail.com> wrote:
>I prefer 800 degrees. Always have done. Esp with small tips. The idea is to get
>the soldering done as fast as quickly, not leave the joint cooking until the
>solder finally melts.
I have to disagree. 700 F is already way above the melting point of
the solder. If you need more heat you might want to use a larger tip,
with greater thermal mass, but higher temps are much more likely to
damage the board.
>I've seen plenty of 'cold' / 'dry' joints arising from the use of 700F tips. I
>even told the manufacturing dept of a certain company to change to 800F tips
>for a certain process but they moaned that 'the tips wear out faster'. So the
>returns rate went up again Bloody idiots.
Good soldering technique will not give cold solder joints, regardless
of the tip temp. High tip temp is probably a poor way to overcome poor
technique. Using a higher temp iron will certainly pump more heat into
the joint in a given time, but it also results in more temp difference
across the joint, so you may be more likely to get what looks like a
good joint on the heated side, but with little penetration.
We've been using Rohs solder for quite a few years now, and I don't
have a bit of trouble with it using a 700 F tip.
Jim Adney
>Remember to replace the shroud that screws on and retains the tip, it is
>part of the magnetic "circuit" and if absent causes that sort of problem.
No, it's not part of the magnetic circuit. The magnestat works just
fine without the sleeve. The only problem is that without the sleeve,
when the tip becomes non-magnetic at the Curie temp it falls out of
the iron.
>Also if you're careful , ie parallel jaw pliers, you can pull off the
>magnastat of a worn tip and change the temp on another good but wrong temp
>tip.
Now THAT's a useful tip! Thanks.
Jim Adney
wrote:
>I did some Googling for soldering iron tips that were specifically
>designed for lead-free soldering. I found several, but none that
>bothered to mention the difference between ordinary and lead-free
>tips. I'll guess that it's pure marketing and that there's no real
>difference in construction, other than operating at about 50F higher
>in temperature.
The tips are made of copper, but copper is slightly soluble in
tin-lead solder, so the copper is plated with iron, which is much less
soluble. To keep the iron from rusting, they do some sort of plating
over the iron. Finally the very tip of the tip is tinned with solder.
I suspect that one difference between a Rohs tip and a non-Rohs tip
would be what solder alloy the tip was tinned with.
It's also possible that they use a slightly different alloy in the
Curie point sensor to change the temp. set point, but I doubt it.
Maybe the thermal contact between the old tip and the new one got so
bad that there could be 150 deg difference in the temp between them.
Seems unlikely, but I suppose it's possible since the tip is exposed
but the sensor is not.
I'm glad you found a simple solution. In 30 years of working with
these WTCP irons, I've never seen a problem like yours.
N Cook
Jim Adney <jad...@vwtype3.org> wrote in message
news:4cm6b45dkh8k9uff9...@4ax.com...
It is easy , on checking different tips rather than soldering, to not
replace the cover. Whether it is a magnetic effect or a positioning effect,
I don't kniow, but it can affect the switching action.
Another tip ;-)
Fit a TO220 transistor insulator/ washer above and below each of the 3
screw-heads that hold the end plate to the plastic handle - stops excess
heat cracking the plastic at the screws.
I must be doing something right , my one is at least 22 years of daily use
with the same heater, switch, cord etc, I've only changed bits. I only
switch on
prior to use , not left on all the time. Gives a time to reflect - is the
kit powered up? , have I confused left and right on turning the board over?
etc.
Arfa Daily
> On Sun, 24 Aug 2008 21:50:04 +0100 Eeyore
> <rabbitsfriend...@hotmail.com> wrote:
>
>>I prefer 800 degrees. Always have done. Esp with small tips. The idea is
>>to get
>>the soldering done as fast as quickly, not leave the joint cooking until
>>the
>>solder finally melts.
>
> I have to disagree. 700 F is already way above the melting point of
> the solder. If you need more heat you might want to use a larger tip,
> with greater thermal mass, but higher temps are much more likely to
> damage the board.
>
>>I've seen plenty of 'cold' / 'dry' joints arising from the use of 700F
>>tips. I
>>even told the manufacturing dept of a certain company to change to 800F
>>tips
>>for a certain process but they moaned that 'the tips wear out faster'. So
>>the
>>returns rate went up again Bloody idiots.
>
> Good soldering technique will not give cold solder joints, regardless
> of the tip temp. High tip temp is probably a poor way to overcome poor
> technique.
I would absolutely dispute that statement
> Using a higher temp iron will certainly pump more heat into
> the joint in a given time, but it also results in more temp difference
> across the joint, so you may be more likely to get what looks like a
> good joint on the heated side, but with little penetration.
??
>
> We've been using Rohs solder for quite a few years now, and I don't
> have a bit of trouble with it using a 700 F tip.
>
>
I would suggest Jim, that it does rather depend on what exactly you are
soldering. If you are making consistently good lead-free joints with a 700
deg Weller tip in all circumstances, then you are doing a lot better than
most of the major manufacturers. Since they started using the stuff, the
service industry has seen a huge leap in bad joints - and not always in
'traditional' places where you might expect to find them.
Whilst you are correct in that a 700 deg tip melts lead-free solder, it does
not do so anything like as well as it does with leaded solder. Although
lead-free solder does not have as nice a melt / flow characteristic as
leaded in the first place, this undesirable quality is made much worse by
not having enough temperature on it - particularly when soldering a
component with a high thermal inertia, such as a connector or power
semiconductor. The fact that lead-free solder is much worse at wetting most
of the metals commonly used in electronic circuit construction, further
exacerbates the problem, and dictates that more aggressive fluxes are used
in the hateful stuff. Unless these are given the opportunity to do their
work, by allowing them to reach the temperatures they need to at the
soldering surface, then the likely result will be a bad joint - and one
that's invisible to the naked eye, and may not give trouble for some time,
at that. Many bad joints in lead-free that I come across in daily work, show
no signs of external distress at all (except that *all* lead-free joints
look distressed), and do not respond to tapping, freezing or heating. The
only conclusion has to be that whilst the solder has stuck ok to the copper
pad, it hasn't to the component leg inside the joint. Probably, a classic
example of the 'cold' joint that engineers your side of the pond, are fond
of calling them.
Use of a bigger tip to improve its own thermal inertia, is not an option
these days for general electronic service work. A finely pointed conical or
small screwdriver tip, is the order of the day. Component pin densities, and
component placement densities, are such that only a small tip and fine gauge
solder are appropriate in most cases, and it's just not a practical
proposition to keep changing tips, depending on what exactly is on your
bench at the time.
When Weller came up with the 700 deg tip, it was with a traditional tin lead
solder alloy in mind. It is the tip that has always been supplied with these
irons from new. Lead-free melts at a temperature of 30 to 50 deg F higher
than leaded, so based on Weller's determination of 700 deg being appropriate
for leaded solder, you would have to extrapolate this thinking to come up
with a tip temperature of perhaps 750 deg, which is what I have both my
variable temperature controlled station, and vacuum desoldering stations set
to, for lead-free work.
So I'm with Graham on this one (who is, like me, experienced in daily
soldering over many many years) in that for lots of lead-free work with a
Weller Magnastat iron, the best combination is a small tip, but with a lot
of heat behind it in the form of it being an 800 deg rated one. I don't
dispute that you can make good joints in lead-free with a 700 deg tip, as I
do it myself, but it does require very considerable care and experience to
'do it right'. There are now more appropriate soldering tools on the market
for lead-free work, than the good old TCP irons.
There are some interesting notes here about why the 'standard' tips burn out
quickly, when used with lead-free
http://www.cooperhandtools.com/europe/sales_literature/documents/Leadfree_Info_GB.pdf
Arfa
Smitty Two
Jim Adney <jad...@vwtype3.org> wrote:
> On Sun, 24 Aug 2008 21:50:04 +0100 Eeyore
> <rabbitsfriend...@hotmail.com> wrote:
>
> >I prefer 800 degrees. Always have done. Esp with small tips. The idea is to
> >get
> >the soldering done as fast as quickly, not leave the joint cooking until the
> >solder finally melts.
>
> I have to disagree. 700 F is already way above the melting point of
> the solder. If you need more heat you might want to use a larger tip,
> with greater thermal mass, but higher temps are much more likely to
> damage the board.
I'm with Graham on this one. I threw all the Wellers in the dumpster a
few years back (tired of fixing them all the time) but when we did use
them we used nothing but 800 degree tips.
Now we've got another brand of iron with dial adjustable temperature and
keep them set at 800, also. For the hobbyist or even repair tech,
waiting two or three seconds for a small joint to heat up might be
acceptable, but for production work it isn't.
And as far as board damage, higher temps are much *less* likely to
damage the board, and the components, because dwell time is drastically
reduced.
Finally as to reduced tip life at higher temps, that cost is offset by
increased efficiency 1000 times over.
William Sommerwerck
>> regardless of the tip temp. High tip temp is probably
>> a poor way to overcome poor technique.
> I would absolutely dispute that statement.
As would I. The temperature has to be at least high enough to bring the
solder to its "liquidus" state. (Which is one of the reasons eutectic solder
is preferable.)
>> Using a higher temp iron will certainly pump more heat into the
>> joint in a given time, but it also results in more temp difference
>> across the joint, so you may be more likely to get what looks
>> like a good joint on the heated side, but with little penetration.
This is bilge.
Rich Webb
<arfa....@ntlworld.com> wrote:
[snip...snip...]
>There are some interesting notes here about why the 'standard' tips burn out
>quickly, when used with lead-free
>
>http://www.cooperhandtools.com/europe/sales_literature/documents/Leadfree_Info_GB.pdf
Interesting phrase there: "Clean the tip on a watery swamp." That one
required a quick mental recalibration...
On that issue, though, what are your thoughts on the use of brass
turnings as a tip cleaner vice a dunk in the swamp? I switched over to
the bowl of brass a while ago and now prefer it to the damp sponge.
--
Rich Webb Norfolk, VA
Jim Yanik
news:prestwhich-DB53A...@news.west.cox.net:
> In article <tgm6b4prg8tpsln65...@4ax.com>,
> Jim Adney <jad...@vwtype3.org> wrote:
>
>> On Sun, 24 Aug 2008 21:50:04 +0100 Eeyore
>> <rabbitsfriend...@hotmail.com> wrote:
>>
>> >I prefer 800 degrees. Always have done. Esp with small tips. The
>> >idea is to get
>> >the soldering done as fast as quickly, not leave the joint cooking
>> >until the solder finally melts.
>>
>> I have to disagree. 700 F is already way above the melting point of
>> the solder. If you need more heat you might want to use a larger tip,
>> with greater thermal mass, but higher temps are much more likely to
>> damage the board.
>
> I'm with Graham on this one. I threw all the Wellers in the dumpster a
> few years back (tired of fixing them all the time) but when we did use
> them we used nothing but 800 degree tips.
>
> Now we've got another brand of iron with dial adjustable temperature
> and keep them set at 800, also. For the hobbyist or even repair tech,
> waiting two or three seconds for a small joint to heat up might be
> acceptable, but for production work it isn't.
>
> And as far as board damage, higher temps are much *less* likely to
> damage the board, and the components, because dwell time is
> drastically reduced.
>
> Finally as to reduced tip life at higher temps, that cost is offset by
> increased efficiency 1000 times over.
my own experience is that dwell time is more critical in regards to PCB
damage.I used 800 degF tips,too.
--
Jim Yanik
jyanik
at
kua.net
whit3rd
> On Sun, 24 Aug 2008 07:25:14 +0200 (CEST), George Orwell
> The outer plating disappears. The part that needs to be cleaned and
> tinned burns up (oxidizes) if left hot and sitting around for 10+
> hours per day. Eventually, I can't tin it any more.
The tips are copper, with an iron-alloy slug for temperature
control, and iron/silver plated. To re-tin after the silver is gone,
use silver solder (90% Ag kind of silver solder... jewelry craft
suppliers will sell by the ounce). It takes at least a hot
propane torch, MAPP or air/acetylene is better, to get to
temperature for this kind of operation.
Eeyore
Arfa Daily wrote:
> "Eeyore" wrote
> > Arfa Daily wrote:
> >> "Eeyore" wrote
> >> >
> >> > Are you unaware of the extra temperature required to melt the lead-free
> >> > solder now mandated in the EU ?
> >>
> >> Just to be clear though, only mandated for items placed on the market
> >> after June 2006, and which don't have a waiver. Items manufactured prior to
>
> >> that using conventional leaded solder, can continue to be repaired /
> reworked
> >> / modified with leaded solder and non RoHS compliant components. New items
> >> for non commercial i.e. amateur use, can still be constructed in whatever
> >> component and solder technology you like.
> >
> > Absolutely, although we have no idea what he's soldering. I still prefer
> > 800F tips for quick neat soldering.
>
> I still use 700s because of the problem of 800s burning out quicker when
> left idling all day,
I don't let that happen and re-tin and wipe the tip regularly. I probably
'waste' as much solder as I use !
Plus Farnell IIRC sells some aggressive (iron) oxide remover that can help
restore a 'damaged' tip. It comes in a little circular tin.
> but I might try 800s again, if only for the improvement
> on the dreaded lead-free. I only said about the RoHS regs because there will
> be a lot of people reading the thread, who perhaps wouldn't understand the
> implications of the legislation. A while back, there was a lot of confusion
> and misconceptions about what it meant to the service industry, not helped
> by a couple of trade bulletins on the subject which were put out by at least
> one major Jap manufacturer, and one soldering equipment manufacturer, and
> which gave entirely the wrong impression. It was this which prompted me to
> write the article.
Fair comment.
Graham
nobody >
Thanks, Arfa for the dissertation on RoHs solder. I'm lucky enough to
have had no dealings with the nasty stuff as most (as in 95%+) of the
repairs in newer stuff I work on is boardswap or exchange. I know I'll
eventually have to mess with it and miss the old leaded stuff I've been
doing since 1959...
I'll have to look up what Pace is doing for RoHs soldering and
desoldering tips.
At least I know my own home WTCPT unit will cope with RoHs solder in a
fashion.
Arfa Daily
I have some, and jolly good it is too, although I wonder just how much
that's eating away at the tip, as well ...
Arfa
Jim Yanik
news:Nx1tk.379066$7f3....@newsfe23.ams2:
IIRC,that has some powdered solder mixed in with the flux.
It cleans AND tins.
(of course,AFAIK,it's not lead-free....)
Jim Adney
wrote:
>
>Jim Adney <jad...@vwtype3.org> wrote in message
>news:4cm6b45dkh8k9uff9...@4ax.com...
>> On Sun, 24 Aug 2008 13:45:52 +0100 "N_Cook" <div...@tcp.co.uk> wrote:
>>
>> >Remember to replace the shroud that screws on and retains the tip, it is
>> >part of the magnetic "circuit" and if absent causes that sort of problem.
>>
>> No, it's not part of the magnetic circuit. The magnestat works just
>> fine without the sleeve. The only problem is that without the sleeve,
>> when the tip becomes non-magnetic at the Curie temp it falls out of
>> the iron.
>It is easy , on checking different tips rather than soldering, to not
>replace the cover. Whether it is a magnetic effect or a positioning effect,
>I don't kniow, but it can affect the switching action.
I just did the most fundamental test on the sleeve. It's not
ferromagnetic at all. Therefore I don't see how it can have any effect
on the magnetic field at all. What kind of effect do you think you've
seen.
>Another tip ;-)
>Fit a TO220 transistor insulator/ washer above and below each of the 3
>screw-heads that hold the end plate to the plastic handle - stops excess
>heat cracking the plastic at the screws.
Sounds reasonable, except that I've never seen heat damage to the
screw anchor points in the plastic. I've certainly seen damage due to
careless starting of the screws without regard to not starting in the
original thread.
I'm surprised that those washers tolerate that heat. I'd expect it to
be a lot hotter there than the application they were designed for.
>I must be doing something right , my one is at least 22 years of daily use
>with the same heater, switch, cord etc, I've only changed bits. I only
>switch on
>prior to use , not left on all the time. Gives a time to reflect - is the
>kit powered up? , have I confused left and right on turning the board over?
>etc.
Mine's 31 years old. Not used all that often, but left on once I'm on
a job. I like these because you CAN leave them on without much harm.
My original heater burned out last year. Other than fixing the base
station outlet wiring when it was new, that was the only repair it's
needed. I think I'm on my second tip. I retin them by stirring them
around in that brown greasy soldering flux.
Jim Adney
<grizzle...@comcast.net> wrote:
>>> Good soldering technique will not give cold solder joints,
>>> regardless of the tip temp. High tip temp is probably
>>> a poor way to overcome poor technique.
>
>> I would absolutely dispute that statement.
>
>As would I. The temperature has to be at least high enough to bring the
>solder to its "liquidus" state. (Which is one of the reasons eutectic solder
>is preferable.)
I certainly agree that we have to work above the liquidus. You're also
quite right about the advantage of working with a eutectic.
700 F is still quite a bit above the liquidus.
Before you get in too deep arguing for higher temps. you might want to
check out the reference that Arfa so kindly provided.
http://www.cooperhandtools.com/europe/sales_literature/documents/Leadfree_Info_GB.pdf
>>> Using a higher temp iron will certainly pump more heat into the
>>> joint in a given time, but it also results in more temp difference
>>> across the joint, so you may be more likely to get what looks
>>> like a good joint on the heated side, but with little penetration.
>
>This is bilge.
It's clear that you disagree, but is it possible that you don't
understand the problem?
Jim Adney
Not sure what you're basing this on, since I doubt that any major
manufacturer is using irons in production. I would expect any real
production to be wave soldered for the last 20 years. I'm sure,
however, that wave soldering, with which I have no experience, has its
own set of problems.
>Whilst you are correct in that a 700 deg tip melts lead-free solder, it does
>not do so anything like as well as it does with leaded solder. Although
>lead-free solder does not have as nice a melt / flow characteristic as
>leaded in the first place, this undesirable quality is made much worse by
>not having enough temperature on it
My own experience doesn't support your claims. I wish I could tell you
exactly what alloy we have at work, but it melts and flows perfectly
well. That could certainly be due to the flux, but I've noticed no
adverse effects from the flux. You also seem to be confusing the
concepts of heat and temperature, and the distinction between the two
is important.
One thing that DOES bother me about the lead free solders is that
everyone suggests that it is important to do repairs with the same
alloy as originally used. However there seem to be several lead free
alloys, and it does not seem that one can tell the difference between
them visually. So how does one know what to do when presented with a
lead free board to repair?
>Use of a bigger tip to improve its own thermal inertia, is not an option
>these days for general electronic service work. A finely pointed conical or
>small screwdriver tip, is the order of the day. Component pin densities, and
>component placement densities, are such that only a small tip and fine gauge
>solder are appropriate in most cases, and it's just not a practical
>proposition to keep changing tips, depending on what exactly is on your
>bench at the time.
I agree that you can't be expected to use a large blunt tip on a fine
pitch high density board, but the link you provided below points out
other ways to accomplish the same thing.
>When Weller came up with the 700 deg tip, it was with a traditional tin lead
>solder alloy in mind. It is the tip that has always been supplied with these
>irons from new. Lead-free melts at a temperature of 30 to 50 deg F higher
>than leaded, so based on Weller's determination of 700 deg being appropriate
>for leaded solder, you would have to extrapolate this thinking to come up
>with a tip temperature of perhaps 750 deg, which is what I have both my
>variable temperature controlled station, and vacuum desoldering stations set
>to, for lead-free work.
This assumes that the 700 F was chosen because it was perfect for
tin/lead solder. There were probably other considerations, too, like
heat content and the typical thermal mass of electrical connections
when these irons first came out. Since many of those connections were
still point-to-point they would have needed much more heat than
present day junctions.
>So I'm with Graham on this one (who is, like me, experienced in daily
>soldering over many many years) in that for lots of lead-free work with a
>Weller Magnastat iron, the best combination is a small tip, but with a lot
>of heat behind it in the form of it being an 800 deg rated one. I don't
>dispute that you can make good joints in lead-free with a 700 deg tip, as I
>do it myself, but it does require very considerable care and experience to
>'do it right'. There are now more appropriate soldering tools on the market
>for lead-free work, than the good old TCP irons.
It's certainly clear that we're each entitled to our opinions.
>There are some interesting notes here about why the 'standard' tips burn out
>quickly, when used with lead-free
>
>http://www.cooperhandtools.com/europe/sales_literature/documents/Leadfree_Info_GB.pdf
That's an interesting link that I haven't seen before and I appreciate
your pointing it out. I can't help mentioning that one thing it says
is that one should be very careful to avoid the temptation to increase
the soldering temperature when using lead free solder.
The first thing I actually noticed about this pdf was that it seemed
to be extremely poorly written. As Cooper Tools is a US company, I
thought it unusual that their English would be so poor. I'm even more
surprised to see that this comes from Cooper Tools GMBH (Germany.)
In spite of the poor translation, I suspect that they have much more
experience with the lead free problem than we do, and the meaning of
their writing is still, in most cases, clear.
Jim Adney
<bbe...@mapson.nozirev.ten> wrote:
>On Tue, 26 Aug 2008 10:56:32 +0100, "Arfa Daily"
><arfa....@ntlworld.com> wrote:
>[snip...snip...]
>>There are some interesting notes here about why the 'standard' tips burn out
>>quickly, when used with lead-free
>>
>>http://www.cooperhandtools.com/europe/sales_literature/documents/Leadfree_Info_GB.pdf
>
>Interesting phrase there: "Clean the tip on a watery swamp." That one
>required a quick mental recalibration...
Yes, that was quite confusing for a few moments.
>On that issue, though, what are your thoughts on the use of brass
>turnings as a tip cleaner vice a dunk in the swamp? I switched over to
>the bowl of brass a while ago and now prefer it to the damp sponge.
I've never used one of those, but I've wondered how they would be. I'd
be concerned that they would wear thru the tip plating quickly and
lead to early death of the tips. Have you noticed any of that?
N Cook
> On Tue, 26 Aug 2008 10:56:32 +0100 "Arfa Daily"
> <arfa....@ntlworld.com> wrote:
>
> >
> >"Jim Adney" <jad...@vwtype3.org> wrote in message
> >news:tgm6b4prg8tpsln65...@4ax.com...
> >> On Sun, 24 Aug 2008 21:50:04 +0100 Eeyore
> >> <rabbitsfriend...@hotmail.com> wrote:
> >>
Don't know about different types of lead-free solder.
But distinguishing lead free I've found is
1/ conical rather than domed solder joints
2/ putting a stainless steel sewing needle in some of the solder after
melting and extracting needle while still molten, it is much more difficult
to remove the cold solder from the needle than doing the same with leaded
solder.
Arfa Daily
"N Cook" <dive...@gazeta.pl> wrote in message
news:g92u87$1bf$1...@inews.gazeta.pl...
And many boards now actually state that they are lead free or "PbF" on the
silk screening. As far as I have been able to tell, it's not so much about
mixing different types of lead-free alloys, which may or may not contain
small traces of other metals such as silver, but more a case of not mixing
lead-free with leaded solder.
To Jim. All of my experience with this stuff is from a service rather than
production point of view. You are of course right that manufacturers use
wave or reflow soldering, and have done for many years. The point I was
making about lead-free joints and Weller TCPs at 700 deg, versus
manufacturers' joints, was perhaps not grammatically well-made. What I was
basically saying was that the manufacturers, with all of their expertise and
expensive production soldering equipment, still can't get to grips with the
stuff themselves, and are still producing equipment littered with bad joints
from day one. So, if you are making consistently good 'production' joints in
lead free, using 700 degree hand soldering equipment designed way way before
any eco-prat had ever come up with the concept of taking the lead out of
solder, then you (your company) are doing, on average, better than the big
boys.
As far as heat and temperature are concerned, I take your point that they
are not the same thing, and I don't think that I am confusing the two. They
are however, inextricably linked to one another by external influences.
Energy, in the form of heat, is what has to be put into a body in order to
raise its temperature. All solder has to have its temperature raised to the
point where its liquid state becomes suitable for making a soldered joint,
and then maintained at that temperature until the joint is completed. The
temperature at which this condition occurs for lead-free solder, is higher
than that of leaded solder. If you are just making small joints, then this
is of no consequence, and a 700 degree tip is fine for the job. With a
leaded joint - even a large one that causes the tip temperature to drop by a
few degrees - that drop is again of little consequence, as there is plenty
of temperature 'overhead' available from a 700 deg tip. However, with
lead-free, 50 degrees of that overhead, have already gone, so if a joint is
any bigger than 'small', the additional temperature drop at the tip, caused
by the joint leaching heat from it, results in a less than adequate tip
temperature being maintained, to correctly complete the joint. The result is
a bad or 'cold' joint. A 700 degree tip simply cannot maintain enough
heatflow into the solder, to keep it at a sufficient temperature to do a
'good job' on anything other than a small joint, and this is particularly
the case where a 'typical' repair workshop tip of small dimensions is used.
I have a repair service for a particular board which uses lead-free, and I
see many of them where the shop that's sending it back to me, have attempted
some rework or component replacement, and it's quite obvious that they have
been trying to use their normal leaded soldering equipment to do the job,
with the inevitable consequences.
I can accept what Cooper say about not being tempted to increase the tip
temperature, but I think that they are probably talking more about not going
up far enough to get the same 'feel' with lead-free, as with leaded. Most
commentators on the subject, including soldering equipment manufacturers,
agree that a higher nominal tip temperature is required to work reliably
with lead-free.
One of the main reasons that manufacturers are having so much trouble with
the stuff, is that they have to run their soldering processes at a higher
temperature. This then brings them close to the maximums that some of the
components can tolerate for any length of time, so they have to compromise
and run the process at a slightly reduced temperature. That is fine until
you have to solder a connector or power semiconductor - particularly one
that is mounted on a heatsink, and that is where many lead-free bad joints
are occuring. Trust me, if manufacturers didn't *have* to run their
processes at a higher temperature, with all of the implications of that,
including a higher energy useage, to cope with lead-free, then they wouldn't
...
Arfa
N Cook
news:n%9tk.26$oT...@newsfe10.ams2...
Is all your info available collated together on a website somewhere. ?
Any comments on the following
If replacing new (ROHS) components to old boards (leaded solder) then scrape
off most of the hard mirror-like finnish on the leads before tining with and
then soldering with Pb-Sn solder
21Century RoHS boards , repair of but not production (heavy solder usage),
use silver solder, or is that likely to lead to as much a problem as mixing
RoHs and PbSn solder.
Bob Shuman
can confirm your assumption that all new production work gets wave soldered
and it has its own set of issues as evidenced by many cold solder joints
found in the field! That said, hand irons are still used for repairs...
Bob
"Jim Adney" <jad...@vwtype3.org> wrote in message
news:hho9b4tj2pqgath5n...@4ax.com...
> Not sure what you're basing this on, since I doubt that any major
> manufacturer is using irons in production. I would expect any real
> production to be wave soldered for the last 20 years. I'm sure,
> however, that wave soldering, with which I have no experience, has its
> own set of problems.
Rich Webb
wrote:
>On Tue, 26 Aug 2008 08:20:47 -0400 Rich Webb
><bbe...@mapson.nozirev.ten> wrote:
>
>>On Tue, 26 Aug 2008 10:56:32 +0100, "Arfa Daily"
>><arfa....@ntlworld.com> wrote:
>>[snip...snip...]
>>>There are some interesting notes here about why the 'standard' tips burn out
>>>quickly, when used with lead-free
>>>
>>>http://www.cooperhandtools.com/europe/sales_literature/documents/Leadfree_Info_GB.pdf
>>
>>Interesting phrase there: "Clean the tip on a watery swamp." That one
>>required a quick mental recalibration...
>
>Yes, that was quite confusing for a few moments.
>
>>On that issue, though, what are your thoughts on the use of brass
>>turnings as a tip cleaner vice a dunk in the swamp? I switched over to
>>the bowl of brass a while ago and now prefer it to the damp sponge.
>
>I've never used one of those, but I've wondered how they would be. I'd
>be concerned that they would wear thru the tip plating quickly and
>lead to early death of the tips. Have you noticed any of that?
None at all. I'm love to see a comparative study, though; must be one
out there somewhere in the vast Intertoobz. I've been pleased with it.
No more hiss'n'sizzle.
Michael A. Terrell
Bob Shuman wrote:
>
> Having worked in electronics assembly and manufacturing for many years, I
> can confirm your assumption that all new production work gets wave soldered
> and it has its own set of issues as evidenced by many cold solder joints
> found in the field! That said, hand irons are still used for repairs...
Wave soldering is going away, and being replaced by reflow ovens, due
to increased SMD construction. The electronics manufacturing I worked
with had three reflow ovens, and no wave solder machine, and that was 10
years ago.
I have only ever seen one wave solder machine in actual use, and all
components were through hole, and it was over 15 years ago.
--
http://improve-usenet.org/index.html
aioe.org, Goggle Groups, and Web TV users must request to be white
listed, or I will not see your messages.
If you have broadband, your ISP may have a NNTP news server included in
your account: http://www.usenettools.net/ISP.htm
There are two kinds of people on this earth:
The crazy, and the insane.
The first sign of insanity is denying that you're crazy.
GMAN
360 has had such a high failure rate.
Eeyore
Jim Adney wrote:
> On Sun, 24 Aug 2008 21:50:04 +0100 Eeyore
> <rabbitsfriend...@hotmail.com> wrote:
>
> >I prefer 800 degrees. Always have done. Esp with small tips. The idea is to get
> >the soldering done as fast as quickly, not leave the joint cooking until the
> >solder finally melts.
>
> I have to disagree. 700 F is already way above the melting point of
> the solder. If you need more heat you might want to use a larger tip,
> with greater thermal mass, but higher temps are much more likely to
> damage the board.
I can assure you they don't unless you take half a minute to make each joint. I an
of course talking about fibreglass (FR$) or CEM material not paper crap.
> >I've seen plenty of 'cold' / 'dry' joints arising from the use of 700F tips. I
> >even told the manufacturing dept of a certain company to change to 800F tips
> >for a certain process but they moaned that 'the tips wear out faster'. So the
> >returns rate went up again Bloody idiots.
>
> Good soldering technique will not give cold solder joints, regardless
> of the tip temp. High tip temp is probably a poor way to overcome poor
> technique. Using a higher temp iron will certainly pump more heat into
> the joint in a given time, but it also results in more temp difference
> across the joint, so you may be more likely to get what looks like a
> good joint on the heated side, but with little penetration.
>
> We've been using Rohs solder for quite a few years now, and I don't
> have a bit of trouble with it using a 700 F tip.
Well let me explain something to you.
The process in question involved soldering a number of TO-220 devices onto a
largish PCB. The TO-220 devices were already mounted on a substantial heatsink.
You could get what 'looked' like a good joint using a 700F tip because of capillary
action up the component lead but maybe 2% of those joints were 'dry' or cold'
because the component leg was itself being heatsunk by the big heatink. 800F tips
fixed it. Then the manufacturing smart alecs went back to 700F tips and as I said
the returns rate went up again.
I recall one example where I was asked to look at the return since it was design of
mine. Took the retaining clip off the TO-200 device and could pull it by hand out of
the PCB leaving perfect 3 rectangular holes where the leads had been in what looked
like perfect solder joints. Of course it worked to begin with because of mechanical
contact which then loosened up with thime.Case proven I think.
In short, you're plain wrong. I have VERY considerable experience in electronics
manufacturing, design and production I will add. Indeed I act as a consultant in the
field.
Graham
Eeyore
Arfa Daily wrote:
snip
> Whilst you are correct in that a 700 deg tip melts lead-free solder, it does
> not do so anything like as well as it does with leaded solder. Although
> lead-free solder does not have as nice a melt / flow characteristic as
> leaded in the first place, this undesirable quality is made much worse by
> not having enough temperature on it - particularly when soldering a
> component with a high thermal inertia, such as a connector or power
> semiconductor.
Absolutely spot on !
Graham
Eeyore
Arfa Daily wrote:
> "Eeyore" <rabbitsfriend...@hotmail.com> wrote in message
> > Arfa Daily wrote:
> >>
> >> Just to be clear though, only mandated for items placed on the market
> >> after June 2006, and which don't have a waiver. Items manufactured prior to
>
> >> that using conventional leaded solder, can continue to be repaired /
> reworked
> >> / modified with leaded solder and non RoHS compliant components. New items
> >> for non commercial i.e. amateur use, can still be constructed in whatever
> >> component and solder technology you like.
> >
> > Absolutely, although we have no idea what he's soldering. I still prefer
> > 800F tips for quick neat soldering.
>
>
> I still use 700s because of the problem of 800s burning out quicker when
> left idling all day,
Well I simply don't let it idle all day. It's guarenteed to give those nasty
'inter-metallic oxides' in the long term anyway that make re-tinning near
impossible. A guy I used to work with would switch on the bench (including iron)
and maybe not use the iron all day. Whenever I noticed, I'd switch it off again.
Why waste electricity anyway ?
Graham
Eeyore
Jim Yanik wrote:
> "Arfa Daily" wrote
> > "Eeyore" wrote
> >> Arfa Daily wrote:
> >>>
> >>> I still use 700s because of the problem of 800s burning out quicker
> >>> when left idling all day,
> >>
> >> I don't let that happen and re-tin and wipe the tip regularly. I
> >> probably 'waste' as much solder as I use !
> >>
> >> Plus Farnell IIRC sells some aggressive (iron) oxide remover that can
> >> help restore a 'damaged' tip. It comes in a little circular tin.
> >
> > I have some, and jolly good it is too, although I wonder just how much
> > that's eating away at the tip, as well ...
Did you never ever use ancient pure copper tips ? That's why Multicore added
a small percentage of copper to some of their solders.
> IIRC,that has some powdered solder mixed in with the flux.
> It cleans AND tins.
That's the stuff.
> (of course,AFAIK,it's not lead-free....)
Damn good news !
Graham
Eeyore
William Sommerwerck wrote:
Quite. The total stress on the components is in fact likely to be be LESS.
Graham
Eeyore
Jim Adney wrote:
> 700 F is still quite a bit above the liquidus.
And how long do you think it's actually going to take the SOLDER to reach that temp ?
Ever heard of thermal inertia ?
Graham
Eeyore
Rich Webb wrote:
I tried one of those brass things and it was useless IMHO. It left loads of crap on the
tip. Use a moist Weller sponge every time.
Graham
Eeyore
GMAN wrote:
> "nobody >" wrote:
> >
> >I'll have to look up what Pace is doing for RoHs soldering and
> >desoldering tips.
> >
> >At least I know my own home WTCPT unit will cope with RoHs solder in a
> >fashion.
> >
> This EU RoHs requirement for lead free solder is the precise reason the XBOX
> 360 has had such a high failure rate.
I hate to think what's lurking in the woodwork. At least aerospace is exempt !
I don't know about car ECUs though. That could be fun. Lead-free hates vibration with a vengeance.
As I may have said elsewhere I know that at least one loudspeaker manufacturer got an exemption because the
sound was causing lead-free lead-out wire terminations to fail. There's implications there for a lot of
sound equipment.
Graham
Eeyore
Bob Shuman wrote:
> Having worked in electronics assembly and manufacturing for many years, I
> can confirm your assumption that all new production work gets wave soldered
> and it has its own set of issues as evidenced by many cold solder joints
> found in the field! That said, hand irons are still used for repairs...
I recall our Bombay sub-contract had a decent wave solder machine with proper
pre-heat etc, good meterials used like Kester solders and fluxes etc. Only
trouble is, every board has a different thermal profile so you should make a
batch of X number of a certain board using one level of pre-heat followed by
another with its level and so on.
However they were not sufficiently organised to be able to do this so they use
some 'average pre-heat' value.
However that pales into insignificance when I discovered what they were up to
at an earlier stage in the process.
We had a LOT of dry/cold joints from them. Prosound / Ahuja. Avoid.
Graham
stra...@yahoo.com
<snip>
> > I still use 700s because of the problem of 800s burning out
quicker when
> > left idling all day,
>
> Well I simply don't let it idle all day. It's guarenteed to give
those nasty
> 'inter-metallic oxides' in the long term anyway that make re-
tinning near
> impossible. A guy I used to work with would switch on the bench
(including iron)
> and maybe not use the iron all day. Whenever I noticed, I'd switch
it off again.
> Why waste electricity anyway ?
>
> Graham
Stop screwing around with Weller if you're serious about soldering and
production certainly qualifies. Get a Metcal. It's ready to use in 10
seconds and with the vastly superior heating element, you don't need
to push it to 800 and live with the temperature 'coasting' down every
time it touches a cold connection. The heating element in the Metcal
_is_ the temp sensor and it's as close to the tip as you can get. Try
one of those and your Wellers will be like both of mine - in a box in
the garage.
So far I've bought 8 Metcal systems, initially one for me personally
and then 6 soldering stations and 1 de-soldering station at work. eBay
is great for this. The cheapest power unit I got was $10 and since it
was local (Los Angeles), I picked it up on the way home and paid no
shipping.
G²
Eeyore
Smitty Two wrote:
> Jim Adney <jad...@vwtype3.org> wrote:
> > Eeyore wrote:
> >
> > >I prefer 800 degrees. Always have done. Esp with small tips. The idea is to
> > >get
> > >the soldering done as fast as quickly, not leave the joint cooking until the
> > >solder finally melts.
> >
> > I have to disagree. 700 F is already way above the melting point of
> > the solder. If you need more heat you might want to use a larger tip,
> > with greater thermal mass, but higher temps are much more likely to
> > damage the board.
>
> I'm with Graham on this one. I threw all the Wellers in the dumpster a
> few years back (tired of fixing them all the time) but when we did use
> them we used nothing but 800 degree tips.
>
> Now we've got another brand of iron with dial adjustable temperature and
> keep them set at 800, also. For the hobbyist or even repair tech,
> waiting two or three seconds for a small joint to heat up might be
> acceptable, but for production work it isn't.
>
> And as far as board damage, higher temps are much *less* likely to
> damage the board, and the components, because dwell time is drastically
> reduced.
>
> Finally as to reduced tip life at higher temps, that cost is offset by
> increased efficiency 1000 times over.
Indeed. Worrying about the cost of an occasional replacemtn tip means someone's
priorities are way askew. Stinks of the MBA culture actually. They never can see
the wood for the trees.
Grahm
Eeyore
N Cook wrote:
> Arfa Daily wrote in message
>
> > One of the main reasons that manufacturers are having so much trouble with
> > the stuff, is that they have to run their soldering processes at a higher
> > temperature. This then brings them close to the maximums that some of the
> > components can tolerate for any length of time, so they have to compromise
> > and run the process at a slightly reduced temperature. That is fine until
> > you have to solder a connector or power semiconductor - particularly one
> > that is mounted on a heatsink, and that is where many lead-free bad joints
> > are occuring. Trust me, if manufacturers didn't *have* to run their
> > processes at a higher temperature, with all of the implications of that,
> > including a higher energy useage, to cope with lead-free, then they
> >wouldn't
>
> Is all your info available collated together on a website somewhere. ?
>
> Any comments on the following
> If replacing new (ROHS) components to old boards (leaded solder) then scrape
> off most of the hard mirror-like finnish on the leads before tining with and
> then soldering with Pb-Sn solder
>
> 21Century RoHS boards , repair of but not production (heavy solder usage),
> use silver solder, or is that likely to lead to as much a problem as mixing
> RoHs and PbSn solder.
I read somewhere a while back that the military, aerospace and telecoms guys
were sending components out to de 'de-tinned' of lead free and re-tinned with
the proper stuff.
Crazy ! Otherwise you can get problems.
Graham
N Cook
When you see brand new components with that hard shiny neat? tin finnish its
hardly surprising there is tin pest problems before anything to do with
microcracking in the solder. Not surprising that such components, after a
few months, can be pulled out by hand leaving neat square holes . It would
take a blow torch almost, to meld with that tin finnish, when on thick say
TOP3 leads.
Arfa Daily
I don't have info particularly collated anywhere, but if you want to contact
me off group with an address that's monitored for input, I'll send you a
copy of the article, which contains references to where I got info, and who
from. I don't think that there is any particular need to remove the surface
of RoHS compliant components' leads. I seem to recall reading somewhere that
most component leads are now tin plated, as in coated in neat tin, rather
than being 'tinned' with any kind of solder, as they were in the past. A
coating of pure tin should not cause any problems when used with a
conventional SnPb solder. As far as using silver solder is concerned, I
don't believe that there is any need to go to those lengths. Given the
limited life and price of modern equipment, I think that any repair that
keeps a piece of kit going for another year is a result, and if the joint
that you made as part of the repair gives up after that time, then san fairy
ann ... Some commentators suggest using a lead-free alloy which contains a
small quantity of silver for hand work. These alloys have a melting point
closer to that of SnPb solder, and similar 'workability', but do of course,
cost significantly more, so I don't bother with them, for the same basic
reasons of equipment life / value.
On that score, just out of interest, I bought a little DVD player from the
local Tesco store last week. It's about the size of a portable player, but
without the LCD screen. It plays every format imaginable, gives a cracking
picture on my (CRT !) TV, and came with all leads and a very comprehensive
user guide in good english. It even has a full function 'credit card' remote
control. How much ? Fifteen quid !! ($27).
If it goes wrong, it's just toss-away. Don't care what solder it's made with
...
Arfa
Arfa Daily
Aha ! When I first started in the business way back when dinosaurs roamed
the countryside, we used Adcola irons with a bakelite 'tortoiseshell'
handle, and a neat spiral of what looked like tinned copper wire wound right
up the length of the business end. Those irons used a solid copper tip, and
we always used 'Savbit' cored solder with them. This solder had added
copper, as you say. The best thing about those solid copper tips, was that
you could file them to any shape that suited your work, without compromising
their performance. A quick touch up with a file fully restored the soldering
tip, which would then tin immediately, and stay tinned until you flicked the
solder blob off, ready to start using it. The solid copper tips were, as I
recall, remarkably long lived, and could be filed into almost non-existence,
before they needed to be replaced. Using irons like that really taught you
the skills of good soldering, skills which stay with you your whole life.
The Antex CN15s and 25s from the same era also had solid copper tips, and
the same things applied. They were the first ones that I can remember
changing over to (first nickel ??) and then iron plating of the bits. Once
that plating wore through though, there was no rescuing the tip, even though
it was copper inside. Touching it up with a file was a one day only fix, and
a new bit was rapidly required. Odd that. perhaps the copper used was a
softer grade or something, once they had it 'protected' by the plating ...
Arfa
Arfa Daily
A few years back, it probaly wouldn't have bothered me, but the older I get,
the shorter the fuse I seem to have. If I were to pick up my iron to do some
soldering, and it wasn't instantly ready to use, I would just get mad at
having to wait for it. I actually don't keep my vacuum desoldering station
powered all the time now since I changed from the Weller to the Pace. The
Weller tips were about seven quid apiece, but lasted for ages, even with the
station left idling. The Pace tips are about the same price, but you have to
buy them five at a time, which hurts a bit more. Add to this that they don't
last above a few weeks when idling, and this has led me to only switch it on
when needed. However, it has to be said that whilst I am waiting for it to
hot up, I fume worse than lead-free solder flux, and tend to pick it up to
start using it as soon as the heat light has started flashing, which then
often results in a clog, as the tip hasn't reached full temperature right up
the (long on the Pace) pick up tube that is part of it ...
Arfa
Yukio YANO
>> On that issue, though, what are your thoughts on the use of brass
>> turnings as a tip cleaner vice a dunk in the swamp? I switched over to
>> the bowl of brass a while ago and now prefer it to the damp sponge.
>
> I tried one of those brass things and it was useless IMHO. It left loads of crap on the
> tip. Use a moist Weller sponge every time.
>
> Graham
>
I switched to using "Stainless Steel" Pot scrubbers nearly 40 years ago,
NOT "Steel wool" It's stuffed into the bottom of the soldering iron
Holder, just a twist inserting or removing the Iron is usually enough
to keep the tip clean. To clear a really dirty tip, a few swipes on the
outside of the holder is sufficient. Do not use "Steel Wool"! it will
dissolve in the hot solder to form all sorts of crud and scraps will
stick to the magnetic tips.
Yukio YANO
Jim Adney
Before you guys all continue to pile on, you might want to actually
read the link that Arfa posted. They are quite emphatic about avoiding
the proceedure you're all supporting. Read it. It's informative.
-
Jim Adney
<rabbitsfriend...@hotmail.com> wrote:
>Ever heard of thermal inertia ?
If you actually mean specific heat, yes.
Jim Adney
<arfa....@ntlworld.com> wrote:
>And many boards now actually state that they are lead free or "PbF" on the
>silk screening. As far as I have been able to tell, it's not so much about
>mixing different types of lead-free alloys, which may or may not contain
>small traces of other metals such as silver, but more a case of not mixing
>lead-free with leaded solder.
The board labeling certainly helps with the lead vs. lead free
problem, but the link you posted also states that the different lead
free alloys should not be mixed. The do seem to imply that mixing lead
in with the lead free is worse, but I can't tell whether the problem
there is an engineering problem or a legal one.
>To Jim. All of my experience with this stuff is from a service rather than
>production point of view. You are of course right that manufacturers use
>wave or reflow soldering, and have done for many years. The point I was
>making about lead-free joints and Weller TCPs at 700 deg, versus
>manufacturers' joints, was perhaps not grammatically well-made. What I was
>basically saying was that the manufacturers, with all of their expertise and
>expensive production soldering equipment, still can't get to grips with the
>stuff themselves, and are still producing equipment littered with bad joints
>from day one. So, if you are making consistently good 'production' joints in
>lead free, using 700 degree hand soldering equipment designed way way before
>any eco-prat had ever come up with the concept of taking the lead out of
>solder, then you (your company) are doing, on average, better than the big
>boys.
We should all remember that the big boys also had soldering problems
before the lead free mandate. AFAIK, those problems were mainly due to
trying to run the boards over the wave soldering machines too fast. I
doubt that present day production quotas are any less compelling.
>As far as heat and temperature are concerned, I take your point that they
>are not the same thing, and I don't think that I am confusing the two. They
>are however, inextricably linked to one another by external influences.
>Energy, in the form of heat, is what has to be put into a body in order to
>raise its temperature. All solder has to have its temperature raised to the
>point where its liquid state becomes suitable for making a soldered joint,
>and then maintained at that temperature until the joint is completed. The
>temperature at which this condition occurs for lead-free solder, is higher
>than that of leaded solder. If you are just making small joints, then this
>is of no consequence, and a 700 degree tip is fine for the job. With a
>leaded joint - even a large one that causes the tip temperature to drop by a
>few degrees - that drop is again of little consequence, as there is plenty
>of temperature 'overhead' available from a 700 deg tip. However, with
>lead-free, 50 degrees of that overhead, have already gone, so if a joint is
>any bigger than 'small', the additional temperature drop at the tip, caused
>by the joint leaching heat from it, results in a less than adequate tip
>temperature being maintained, to correctly complete the joint. The result is
>a bad or 'cold' joint. A 700 degree tip simply cannot maintain enough
>heatflow into the solder, to keep it at a sufficient temperature to do a
>'good job' on anything other than a small joint, and this is particularly
>the case where a 'typical' repair workshop tip of small dimensions is used.
I'm glad to see that you do understand the difference between heat and
temperature, and the causes and effects of heat flow, but we won't
settle this argument until someone can post the actual melting point
of 63/37 and the solidus/liquidus of some of the lead free solders.
ISTR that the good old eutectic stuff melted at something like 370 F,
but I wouldn't bet on it. I'm pretty sure that it's somewhere below
400 F, so another 50 F is not such a big deal.
>I have a repair service for a particular board which uses lead-free, and I
>see many of them where the shop that's sending it back to me, have attempted
>some rework or component replacement, and it's quite obvious that they have
>been trying to use their normal leaded soldering equipment to do the job,
>with the inevitable consequences.
Cooper appears to recommend tools that start at the same temp, but
have greater thermal mass and better thermal conductivity to the work.
They also have some additional recommendations which I have not tried.
Weller sells a preheat "table" which heats your board from the bottom
while you solder on top (or vice versa.) This would clearly help
produce joints that have been heated to an even temperature, and
Weller makes the point that it reduces stress in the finished joint.
They also sell a special iron which floods the work with an inert gas
while you solder.
Both of these seem pretty burdensome and extreme to me.
>I can accept what Cooper say about not being tempted to increase the tip
>temperature, but I think that they are probably talking more about not going
>up far enough to get the same 'feel' with lead-free, as with leaded. Most
>commentators on the subject, including soldering equipment manufacturers,
>agree that a higher nominal tip temperature is required to work reliably
>with lead-free.
I don't find an actual tip temperature in the Weller link, but they do
say to use the lowest temperature possible. Since I find that I have
no trouble (really!) soldering with a 700 F tip, and everyone in our
lab uses the same irons with the same alloys, I see no reason why
anything hotter would be justified.
It is also quite true that I do not work under a quota requirement,
nor am I paid by the joint, so I don't mind if the joint takes 3
seconds instead of 2. OTOH, I'm not really much aware of any change in
my soldering habits or technique since I used my first WTCP iron in
about 1977.
My earlier irons, starting with an American Beauty in about 1955,
required much different skills, and I was young and foolish then, so
when I go back and look at some of that work I often have to "tidy" it
up a bit.
>One of the main reasons that manufacturers are having so much trouble with
>the stuff, is that they have to run their soldering processes at a higher
>temperature. This then brings them close to the maximums that some of the
>components can tolerate for any length of time, so they have to compromise
>and run the process at a slightly reduced temperature. That is fine until
>you have to solder a connector or power semiconductor - particularly one
>that is mounted on a heatsink, and that is where many lead-free bad joints
>are occuring. Trust me, if manufacturers didn't *have* to run their
>processes at a higher temperature, with all of the implications of that,
>including a higher energy useage, to cope with lead-free, then they wouldn't
>...
I think they would do just as well if they ran more slowly at lower
temps, but they probably find that is even more expensive than the
higher temps.
We won't really know the answer until we know the actual liquidus
temps of the Rohs solders. A check here gives us some facts to
consider:
http://kester.com/en-US/technical/alloy.aspx
I note that most of these range from 420 to 450 F, with 2 eutectic
alloys that melt at 430 and 440. 700 F seems like plenty of overhead
for working at those ranges, at least to me.
N Cook
>
You had it easy - when I started soldering it was a matter of heating , on
the gas stove, a shaped block of copper on a steel shaft with wooden handle.
Eeyore
Arfa Daily wrote:
> I don't have info particularly collated anywhere, but if you want to contact
> me off group with an address that's monitored for input, I'll send you a
> copy of the article, which contains references to where I got info, and who
> from. I don't think that there is any particular need to remove the surface
> of RoHS compliant components' leads. I seem to recall reading somewhere that
> most component leads are now tin plated, as in coated in neat tin, rather
> than being 'tinned' with any kind of solder, as they were in the past. A
> coating of pure tin should not cause any problems when used with a
> conventional SnPb solder.
The military etc are still worried because of potential tin whiskers with
closely spaced device leads.
There are known examples of such inter-lead shorts and they can support up to
30mA I read somewhere IIRC. I had a fantastic picture of one once. It shorted
out a *crystal*.
Graham
Eeyore
Arfa Daily wrote:
> "Eeyore" wrote
> > Jim Yanik wrote:
> >> "Arfa Daily" wrote
> >> > "Eeyore" wrote
> >> >> Arfa Daily wrote:
> >> >>>
> >> >>> I still use 700s because of the problem of 800s burning out quicker
> >> >>> when left idling all day,
> >> >>
> >> >> I don't let that happen and re-tin and wipe the tip regularly. I
> >> >> probably 'waste' as much solder as I use !
> >> >>
> >> >> Plus Farnell IIRC sells some aggressive (iron) oxide remover that can
> >> >> help restore a 'damaged' tip. It comes in a little circular tin.
> >> >
> >> > I have some, and jolly good it is too, although I wonder just how much
> >> > that's eating away at the tip, as well ...
> >
> > Did you never ever use ancient pure copper tips ? That's why Multicore
> > added a small percentage of copper to some of their solders.
> >
> >> IIRC,that has some powdered solder mixed in with the flux.
> >> It cleans AND tins.
> >
> > That's the stuff.
> >
> >> (of course,AFAIK,it's not lead-free....)
> >
> > Damn good news !
>
>
> Aha ! When I first started in the business way back when dinosaurs roamed
> the countryside, we used Adcola irons with a bakelite 'tortoiseshell'
> handle, and a neat spiral of what looked like tinned copper wire wound right
> up the length of the business end. Those irons used a solid copper tip, and
> we always used 'Savbit' cored solder with them. This solder had added
> copper, as you say.
That was the stuff. Couldn't remember the name.
> The best thing about those solid copper tips, was that
> you could file them to any shape that suited your work, without compromising
> their performance. A quick touch up with a file fully restored the soldering
> tip, which would then tin immediately, and stay tinned until you flicked the
> solder blob off, ready to start using it. The solid copper tips were, as I
> recall, remarkably long lived, and could be filed into almost non-existence,
> before they needed to be replaced.
Oh yes I remember well.
> Using irons like that really taught you
> the skills of good soldering, skills which stay with you your whole life.
> The Antex CN15s and 25s from the same era also had solid copper tips, and
> the same things applied. They were the first ones that I can remember
> changing over to (first nickel ??) and then iron plating of the bits.
Yup. The Antex C15 was my first 'serious' iron for working on miniature
components like TO-18 transistors. I recall BC109s were 6s/6d from Henry's Radio
back then and building my first pre-amps from the Mullard Audio and Radio
applications book.
> Once
> that plating wore through though, there was no rescuing the tip, even though
> it was copper inside. Touching it up with a file was a one day only fix, and
> a new bit was rapidly required. Odd that. perhaps the copper used was a
> softer grade or something, once they had it 'protected' by the plating ...
Possibly just purer ?
Graham
Eeyore
Jim Adney wrote:
> Eeyore wrote:
> >William Sommerwerck wrote:
> >
> >> >> Good soldering technique will not give cold solder joints,
> >> >> regardless of the tip temp. High tip temp is probably
> >> >> a poor way to overcome poor technique.
> >>
> >> > I would absolutely dispute that statement.
> >>
> >> As would I. The temperature has to be at least high enough to bring the
> >> solder to its "liquidus" state. (Which is one of the reasons eutectic solder
> >> is preferable.)
> >>
> >> >> Using a higher temp iron will certainly pump more heat into the
> >> >> joint in a given time, but it also results in more temp difference
> >> >> across the joint, so you may be more likely to get what looks
> >> >> like a good joint on the heated side, but with little penetration.
> >>
> >> This is bilge.
> >
> >Quite. The total stress on the components is in fact likely to be be LESS.
>
> Before you guys all continue to pile on, you might want to actually
> read the link that Arfa posted. They are quite emphatic about avoiding
> the proceedure you're all supporting. Read it. It's informative.
My experience says otherwise. I'll have to time how long it takes to solder say a
1/4W resistor but it's certainly less than the 3 seconds or so some have mentioned
with 700F tips.
Plus note my post about those cold joints that plagued an amp design that just
'went away' with 800F tips.
Graham
Arfa Daily
<snip>
>
> The board labeling certainly helps with the lead vs. lead free
> problem, but the link you posted also states that the different lead
> free alloys should not be mixed. The do seem to imply that mixing lead
> in with the lead free is worse, but I can't tell whether the problem
> there is an engineering problem or a legal one.
>
<snip>
>> .....ever come up with the concept of taking the lead out of
>>solder, then you (your company) are doing, on average, better than the big
>>boys.
>
> We should all remember that the big boys also had soldering problems
> before the lead free mandate. AFAIK, those problems were mainly due to
> trying to run the boards over the wave soldering machines too fast. I
> doubt that present day production quotas are any less compelling.
>
<snip>
>> ..... A 700 degree tip simply cannot maintain enough
>>heatflow into the solder, to keep it at a sufficient temperature to do a
>>'good job' on anything other than a small joint, and this is particularly
>>the case where a 'typical' repair workshop tip of small dimensions is
>>used.
>
> I'm glad to see that you do understand the difference between heat and
> temperature, and the causes and effects of heat flow, but we won't
> settle this argument until someone can post the actual melting point
> of 63/37 and the solidus/liquidus of some of the lead free solders.
> ISTR that the good old eutectic stuff melted at something like 370 F,
> but I wouldn't bet on it. I'm pretty sure that it's somewhere below
> 400 F, so another 50 F is not such a big deal.
>
<snip>
>> ... Most commentators on the subject, including soldering equipment
>> manufacturers,
>>agree that a higher nominal tip temperature is required to work reliably
>>with lead-free.
>
> I don't find an actual tip temperature in the Weller link, but they do
> say to use the lowest temperature possible. Since I find that I have
> no trouble (really!) soldering with a 700 F tip, and everyone in our
> lab uses the same irons with the same alloys, I see no reason why
> anything hotter would be justified.
>
> It is also quite true that I do not work under a quota requirement,
> nor am I paid by the joint, so I don't mind if the joint takes 3
> seconds instead of 2. OTOH, I'm not really much aware of any change in
> my soldering habits or technique since I used my first WTCP iron in
> about 1977.
>
>
<snip>
>> ...Trust me, if manufacturers didn't *have* to run their
>>processes at a higher temperature, with all of the implications of that,
>>including a higher energy useage, to cope with lead-free, then they
>>wouldn't
>>...
>
> I think they would do just as well if they ran more slowly at lower
> temps, but they probably find that is even more expensive than the
> higher temps.
>
> We won't really know the answer until we know the actual liquidus
> temps of the Rohs solders. A check here gives us some facts to
> consider:
>
> http://kester.com/en-US/technical/alloy.aspx
>
> I note that most of these range from 420 to 450 F, with 2 eutectic
> alloys that melt at 430 and 440. 700 F seems like plenty of overhead
> for working at those ranges, at least to me.
>
> -
> -----------------------------------------------
> Jim Adney jad...@vwtype3.org
> Madison, WI 53711 USA
> -----------------------------------------------
All points noted, and for the most part, agreed with. I think what I am
saying, and probably Graham too, if I understand him correctly, is that for
most modern service work, a small tip is needed, which is less than ideal
for transferring heat from the iron's element to the actual joint, which
should be being made by the joint itself being heated, and the solder 'fed
in', as is the case with leaded solder. The result of that less than ideal
sized tip is that inevitably, as a large joint leaches heat from it, the
temperature drops, perhaps 50 or more degrees. With leaded solder, this is
of little consequence, as the drop in temperature is still well above the
point where the solder is able to be worked, to create a guaranteed good
joint. However, that said, try it on a big enough joint, and that won't be
the case. With lead-free, the drop in tip temperature is of greater
significance, as it readily causes poor workability of the solder, a 50 or
more degree drop taking you a lot nearer to the point where the solder works
'pasty' rather than fluidly.
So in this case, a tip that starts off at 800 deg and then drops towards 700
'under load' appears to represent a tool better suited to the job 'on
average', bearing in mind that as service engineers, we are seeing many
types of equipment that need, in theory at least, a similar variety of
different soldering equipment. So what we are using is a working compromise,
that has to be able to cope with leaded as well as lead-free solder, and
everything from IC pins to BNC connectors or worse.
To some extent, the points raised are moot in that there are now much better
tools on the market for coping with the modern situation, without having to
compromise. Someone mentioned Metcal stations for instance. Any station with
a tight control loop, is much better than a TCP for general service work
these days. I run an Antex temperature adjustable station, which I keep
idling at about 680 degrees. I turn it up to 750 when using lead-free, as I
find from a purely personal point of view, that this temperature suits both
me, and the Ersin 306 alloy that I use. I still keep my TCP running, with a
700 deg tip mostly, more out of comfort as it has been with me many years,
but I do find that I use it less now.
As far as the manufacturers having trouble with the stuff goes, I don't
think that it is to do with deadlines per se. I can remember when PCBs were
first around, and the technology advanced very quickly, driven mainly by the
big Jap consumer market manufacturers, to the point where bad joints on
their equipment were virtually unheard of, and that has remained the
situation for many years now. Given that wave and reflow soldering were
fully mature and largely trouble free and reliable technologies, one would
have expected that the degree of understanding that they must have of the
processes involved, would have allowed them to slip seamlessly into
similarly reliable manufacturing with lead-free. This doesn't appear to have
been the case, and equipment is still coming out of factories with less than
satisfactory joints, which tells me that the problem is with the technology
itself, not how the manufacturers are incorporating it into their overall
manufacturing time budget. When push comes to shove, it is a replacement
technology that arguably wasn't required in the first place. The original
technology involved in soldering was the right one, as has been shown over
many years, and the replacement uses materials deemed to be ecologically
better, but which don't actually readily do the job that they are needed to.
The lead-free solder is being 'made to fit' on the back of the "green"
ticket if you will, and sod the consequences ...
Arfa
Eeyore
Jim Adney wrote:
> Eeyore wrote:
>
> >Ever heard of thermal inertia ?
>
> If you actually mean specific heat, yes.
And what you mean is 'heat capacity' which is NOT the same thing !
Although it's value depends on specific heat too.
" Heat capacity (symbol: Cp) — as distinct from specific heat capacity —
is the measure of the heat energy required to increase the temperature
of an object by a certain temperature interval. "
http://en.wikipedia.org/wiki/Heat_capacity
Graham
Arfa Daily
>> Is all your info available collated together on a website somewhere. ?
>>
>> Any comments on the following
>> If replacing new (ROHS) components to old boards (leaded solder) then
>> scrape
>> off most of the hard mirror-like finnish on the leads before tining with
>> and
>> then soldering with Pb-Sn solder
>>
>> 21Century RoHS boards , repair of but not production (heavy solder
>> usage),
>> use silver solder, or is that likely to lead to as much a problem as
>> mixing
>> RoHs and PbSn solder.
>>
>>
>> --
>> Diverse Devices, Southampton, England
>> electronic hints and repair briefs , schematics/manuals list on
>> http://home.graffiti.net/diverse:graffiti.net/
>>
>>
>>
>
> I don't have info particularly collated anywhere, but if you want to
> contact me off group with an address that's monitored for input, I'll send
> you a copy of the article, which contains references to where I got info,
> and who from.
On its way. Check your incoming. Let me know if any probs.
Arfa
Arfa Daily
Been some interesting stuff recently in Elektor mag on the subject, and how
the old AF117's used to fail in SO mixers used in early tranny radios. Seems
that was due to whiskers growing inside the metal can of the transistor,
which was tin plated, and shorting to the transistor itself. Many engineers
just used to snip the screen lead on the transistor, but I found that if you
quickly jabbed a screwdriver across between the screen and collector leads,
the short magically disappeared. I guess it was blasting off the microscopic
whisker by vapourising it.
Arfa
Arfa Daily
Sent again using the first 'reserve' address. Let me know ...
Arfa
Andy Cuffe
wrote:
>
>I've never used one of those, but I've wondered how they would be. I'd
>be concerned that they would wear thru the tip plating quickly and
>lead to early death of the tips. Have you noticed any of that?
>
>-
I also use one of those, and if anything, my tips last longer.
Andy Cuffe
N Cook
All received, not had a chance to read it yet
Eeyore
Arfa Daily wrote:
> "Eeyore" <rabbitsfriend...@hotmail.com> wrote in message
> >
> > The military etc are still worried because of potential tin whiskers with
> > closely spaced device leads.
> >
> > There are known examples of such inter-lead shorts and they can support up
> > to 30mA I read somewhere IIRC. I had a fantastic picture of one once. It
> > shorted out a *crystal*.
>
>
> Been some interesting stuff recently in Elektor mag on the subject, and how
> the old AF117's used to fail in SO mixers used in early tranny radios. Seems
> that was due to whiskers growing inside the metal can of the transistor,
> which was tin plated, and shorting to the transistor itself. Many engineers
> just used to snip the screen lead on the transistor, but I found that if you
> quickly jabbed a screwdriver across between the screen and collector leads,
> the short magically disappeared. I guess it was blasting off the microscopic
> whisker by vapourising it.
Now how did you devise that technique ?
Graham
nobody >
The same thing happened with early-manufactured 72 'pin' SIMMs that had
tin contacts (typically the cheap generic RAM sitcks). 30 'pin' tin
contact SIMMs were 'coarse pitch' enough that the problem occurred rarely.
I also saw the same issue on some UK-manufactured electric traffic
counters (those boxes with the hoses laid across the pavement). They
left the thru-leads so long that the tin coating on on the leads
protruding out of the hole would grow whiskers. We had no schematics and
the chips were all marked only with proprietary numbers, all we could do
to fix them locally was to check discrete components on guesstimate as
to what their function was, and do an extremely close scrutiny on the
boards. We found those whiskers on quite a few of them, so it became a
shop standard to trim all the leads on the boards and scrub them before
giving up and RMAing the units. That cured probably 70% of the problems.
Eeyore
"nobody >" wrote:
> Eeyore wrote:
> > Arfa Daily wrote:
> >
> >> I don't have info particularly collated anywhere, but if you want to contact
> >> me off group with an address that's monitored for input, I'll send you a
> >> copy of the article, which contains references to where I got info, and who
> >> from. I don't think that there is any particular need to remove the surface
> >> of RoHS compliant components' leads. I seem to recall reading somewhere that
> >> most component leads are now tin plated, as in coated in neat tin, rather
> >> than being 'tinned' with any kind of solder, as they were in the past. A
> >> coating of pure tin should not cause any problems when used with a
> >> conventional SnPb solder.
> >
> > The military etc are still worried because of potential tin whiskers with
> > closely spaced device leads.
> >
> > There are known examples of such inter-lead shorts and they can support up to
> > 30mA I read somewhere IIRC. I had a fantastic picture of one once. It shorted
> > out a *crystal*.
>
> The same thing happened with early-manufactured 72 'pin' SIMMs that had
> tin contacts (typically the cheap generic RAM sitcks). 30 'pin' tin
> contact SIMMs were 'coarse pitch' enough that the problem occurred rarely.
>
> I also saw the same issue on some UK-manufactured electric traffic
> counters (those boxes with the hoses laid across the pavement). They
> left the thru-leads so long that the tin coating on on the leads
> protruding out of the hole would grow whiskers. We had no schematics and
> the chips were all marked only with proprietary numbers, all we could do
> to fix them locally was to check discrete components on guesstimate as
> to what their function was, and do an extremely close scrutiny on the
> boards. We found those whiskers on quite a few of them, so it became a
> shop standard to trim all the leads on the boards and scrub them before
> giving up and RMAing the units. That cured probably 70% of the problems.
Pathetic.
Bloody alleged 'greens' and gullible politicians.. Combine the two and you have a
disaster.
Graham
Arfa Daily
Christ knows Graham ! I was about 18 at the time and probably about the only
one in the workshop who was reasonably comfortable with the new fangled
transistors ...
Thinking about it, the leads went E-B-Scr-space-C. It was probably one of
those fortuitous 'mistakes' where I was measuring the collector voltage, and
the meter probe slipped ...
Arfa
N Cook
>
> "N Cook" <dive...@gazeta.pl> wrote in message
> news:g93d6p$gu3$1...@inews.gazeta.pl...
> > Arfa Daily <arfa....@ntlworld.com> wrote in message
> > news:n%9tk.26$oT...@newsfe10.ams2...
> >>
> >> "N Cook" <dive...@gazeta.pl> wrote in message
> >> news:g92u87$1bf$1...@inews.gazeta.pl...
> >> > Jim Adney <jad...@vwtype3.org> wrote in message
> >> > news:hho9b4tj2pqgath5n...@4ax.com...
> >> >> On Tue, 26 Aug 2008 10:56:32 +0100 "Arfa Daily"
> >> >> <arfa....@ntlworld.com> wrote:
> >> >>
> >> >> >
> >> >> >"Jim Adney" <jad...@vwtype3.org> wrote in message
> >> >> >news:tgm6b4prg8tpsln65...@4ax.com...
> >> >> >> On Sun, 24 Aug 2008 21:50:04 +0100 Eeyore
> >> >> >> <rabbitsfriend...@hotmail.com> wrote:
> >> >> >>
> >> >
> >> >
> >> > Don't know about different types of lead-free solder.
> >> > But distinguishing lead free I've found is
> >> > 1/ conical rather than domed solder joints
> >> > 2/ putting a stainless steel sewing needle in some of the solder
after
> >> > melting and extracting needle while still molten, it is much more
> >> > difficult
> >> > to remove the cold solder from the needle than doing the same with
> > leaded
> >> > solder.
> >> >
> >> >
>
> I don't have info particularly collated anywhere, but if you want to
contact
> me off group with an address that's monitored for input, I'll send you a
> copy of the article, which contains references to where I got info, and
who
> from. I don't think that there is any particular need to remove the
surface
> of RoHS compliant components' leads. I seem to recall reading somewhere
that
> most component leads are now tin plated, as in coated in neat tin, rather
> than being 'tinned' with any kind of solder, as they were in the past. A
> coating of pure tin should not cause any problems when used with a
> conventional SnPb solder. As far as using silver solder is concerned, I
> don't believe that there is any need to go to those lengths. Given the
> limited life and price of modern equipment, I think that any repair that
> keeps a piece of kit going for another year is a result, and if the joint
> that you made as part of the repair gives up after that time, then san
fairy
> ann ... Some commentators suggest using a lead-free alloy which contains a
> small quantity of silver for hand work. These alloys have a melting point
> closer to that of SnPb solder, and similar 'workability', but do of
course,
> cost significantly more, so I don't bother with them, for the same basic
> reasons of equipment life / value.
>
My experiences of RoHS, so far
For post 2006 repair work I use (lead-free) silver solder , despite it
leaving a grey "bad" looking joint. For an average repair, for me, this
costs to about 0.06 GBP/ 0.12 USD per job which is fine be me. Repeat,
repair not production or even re-work production. And very little
suck-it-and-see repair, tending to zero in on the errant component at the
first or second target, minimal trace cutting (consequential bridging
repair). At the moment about 20 percent lead-free jobs, as mainly old stuff
still. In years to come where it becomes obvious that complete, all
component, re-work is required then perhaps Ag would be too much of an
overhead.
Some of the bad joints i've seen in the last few years, you just do not come
across with leaded solder. And we're talking about kit only a year or two
old. eg totally unstressed (in temperature terms but subjected to vibration)
1/3 watt resistors (so no heatsinking at production) that you can pull out
of the "solder" joint by finger force.
No jobs have bounced back due to mixing of Ag and Pb-free solder (so far)
Likewise I must have repaired pre-2006 boards , that had early Pb-free
solder, using leaded solder in repair and likewise those jobs have not
bounced back, so far.
Jim Adney
<arfa....@ntlworld.com> wrote:
>All points noted, and for the most part, agreed with. I think what I am
>saying, and probably Graham too, if I understand him correctly, is that for
>most modern service work, a small tip is needed, which is less than ideal
>for transferring heat from the iron's element to the actual joint, which
>should be being made by the joint itself being heated, and the solder 'fed
>in', as is the case with leaded solder. The result of that less than ideal
>sized tip is that inevitably, as a large joint leaches heat from it, the
>temperature drops, perhaps 50 or more degrees. With leaded solder, this is
>of little consequence, as the drop in temperature is still well above the
>point where the solder is able to be worked, to create a guaranteed good
>joint. However, that said, try it on a big enough joint, and that won't be
>the case. With lead-free, the drop in tip temperature is of greater
>significance, as it readily causes poor workability of the solder, a 50 or
>more degree drop taking you a lot nearer to the point where the solder works
>'pasty' rather than fluidly.
I agree with this, except that in the case where I encounter a large
joint, I always find that I can heat the joint using the side of the
tip, thus greatly increasing the thermal conductivity.
>So in this case, a tip that starts off at 800 deg and then drops towards 700
>'under load' appears to represent a tool better suited to the job 'on
>average', bearing in mind that as service engineers, we are seeing many
>types of equipment that need, in theory at least, a similar variety of
>different soldering equipment. So what we are using is a working compromise,
>that has to be able to cope with leaded as well as lead-free solder, and
>everything from IC pins to BNC connectors or worse.
Since I've never made any temp measurements across a soldered joint, I
really don't know how much temp drop one might find. It appears that
we have 250 F of headroom available with a 700 iron, which seems like
it should be plenty, but I have no data to support that. Weller's
suggestion to preheat the bottom side of the board while soldering
from the top (or vice versa) would seem to support your claim that the
700 F tip may not be sufficient, but it would be more helpful if they
had specific temp recommendations.
>To some extent, the points raised are moot in that there are now much better
>tools on the market for coping with the modern situation, without having to
>compromise. Someone mentioned Metcal stations for instance. Any station with
>a tight control loop, is much better than a TCP for general service work
>these days.
One of my co-workers uses a Metcal for surface mount work and swears
by it. Since it heats and senses right at the tip, it's bound to be
better as you say.
>As far as the manufacturers having trouble with the stuff goes, I don't
>think that it is to do with deadlines per se. I can remember when PCBs were
>first around, and the technology advanced very quickly, driven mainly by the
>big Jap consumer market manufacturers, to the point where bad joints on
>their equipment were virtually unheard of, and that has remained the
>situation for many years now. Given that wave and reflow soldering were
>fully mature and largely trouble free and reliable technologies, one would
>have expected that the degree of understanding that they must have of the
>processes involved, would have allowed them to slip seamlessly into
>similarly reliable manufacturing with lead-free. This doesn't appear to have
>been the case, and equipment is still coming out of factories with less than
>satisfactory joints, which tells me that the problem is with the technology
>itself, not how the manufacturers are incorporating it into their overall
>manufacturing time budget. When push comes to shove, it is a replacement
>technology that arguably wasn't required in the first place. The original
>technology involved in soldering was the right one, as has been shown over
>many years, and the replacement uses materials deemed to be ecologically
>better, but which don't actually readily do the job that they are needed to.
>The lead-free solder is being 'made to fit' on the back of the "green"
>ticket if you will, and sod the consequences ...
I tend to work (repair) a lot of items that are quite old, so I've
seen a number of failed joints on old boards. They tend to crack
around large joints where not enough heat got into that joint to allow
the solder to wick in far enough to make a sound mechanical
connection. I can only speculate that the cause was insufficient
pre-heat time in the wave soldering machine, due to running the line
too fast.
Now, I have a confession to make. When I started my current job 9
years ago, they told me they were switching to lead free solder. I
tried some of it at that time and it seemed fine. In the course of
this conversation I realized that I had no idea exactly what version
of lead-free we were using, so today I went into our shop and looked
at one of the spools, since I usually just pull off a few feet to take
back to my office where my bench is. What I found was spools of 60/40
tin/lead. I don't know how long that's been in use here, or if they
ever bought any more of the Rohs solder.
So at this point I have to admit that it's possible that I've been
mistaken for the past 9 years and I may have almost no Rohs soldering
experience. I apologize for my statements to the contrary. It now
seems clear why my "experience" with Rohs solder seemed to be so
positive. I'll try to find some actual Rohs to try.
I DO know that my previous workplace HAS made the switch to Rohs. I
still have friends there and it is a manufacturing environment. One of
those friends is one of their electrical engineers, so I'll make a
point of asking him how that changeover went and whether it has given
them any continuing problems.
Maybe I'll find that they went to 800 F tips, or maybe not.
Eeyore
Arfa Daily wrote:
> "Eeyore" wrote
> > Arfa Daily wrote:
> >>
> >> Been some interesting stuff recently in Elektor mag on the subject, and
> >> how the old AF117's used to fail in SO mixers used in early tranny radios.
> >> Seems that was due to whiskers growing inside the metal can of the
> transistor,
> >> which was tin plated, and shorting to the transistor itself. Many
> >> engineers just used to snip the screen lead on the transistor, but I found
> that if
> >> you quickly jabbed a screwdriver across between the screen and collector
> >> leads, the short magically disappeared. I guess it was blasting off the
> >> microscopic whisker by vapourising it.
> >
> > Now how did you devise that technique ?
>
> Christ knows Graham ! I was about 18 at the time and probably about the only
> one in the workshop who was reasonably comfortable with the new fangled
> transistors ...
>
> Thinking about it, the leads went E-B-Scr-space-C. It was probably one of
> those fortuitous 'mistakes' where I was measuring the collector voltage, and
> the meter probe slipped ...
Unlike me designing power amps where a similar slip tends to result in a lot of
magic smoke being let out.
Graham
Eeyore
N Cook wrote:
> Some of the bad joints i've seen in the last few years, you just do not come
> across with leaded solder. And we're talking about kit only a year or two
> old. eg totally unstressed (in temperature terms but subjected to vibration)
> 1/3 watt resistors (so no heatsinking at production) that you can pull out
> of the "solder" joint by finger force.
Vibration is the killer with lead-free. Never mind the tin whiskers.
But did you also know about tin pest ? I have no idea how much the temperature
is affected by the copper (and silver for the rich) in lead-free but the Japs
also use bismuth IIRC.
" At 13.2 degrees Celsius (about 56 degrees Fahrenheit) and below, pure tin
transforms from the (silvery, ductile) allotrope of ?-modification white tin to
brittle, ?-modification grey tin. Eventually it decomposes into powder, hence
the name tin pest.
The decomposition will catalyze itself, which is why the reaction seems to speed
up once it starts; the mere presence of tin pest leads to more tin pest. Tin
objects at low temperatures will simply disintegrate. "
http://en.wikipedia.org/wiki/Tin_pest
Graham
N_Cook
In the situation where you can just pull a component from a board, not
desoledered, it is sometimes possible to see a grey powdery surface to the
component, suggestive of tin-pest.
And for using tin tinned new RoHS components destined for both old boards
and Pb-Sn solder or new boards and silver solder, burr the tin off with a
"diamond" cintride burr on a Dremmel, before tinning with the intended
solder. A solid layer of tin is asking for trouble - turn to dust tin-pest.
N Cook
I'm not sure the critical temp is 13 deg C, has someone confused 13 deg F
and 13 deg C?. 13 degree C is quite a normal unheated room temperature.
Eeyore
N_Cook wrote:
> Eeyore wrote
> > N Cook wrote:
> >
> > > Some of the bad joints i've seen in the last few years, you just do not
> come across with leaded solder. And we're talking about kit only a year or
> two old. eg totally unstressed (in temperature terms but subjected to
> vibration) 1/3 watt resistors (so no heatsinking at production) that you can
> pull
> out of the "solder" joint by finger force.
> >
> > Vibration is the killer with lead-free. Never mind the tin whiskers.
> >
> > But did you also know about tin pest ? I have no idea how much the
> temperature is affected by the copper (and silver for the rich) in lead-free
> but the
> Japs also use bismuth IIRC.
> >
> > " At 13.2 degrees Celsius (about 56 degrees Fahrenheit) and below, pure
> tin transforms from the (silvery, ductile) allotrope of beta-modification
> white
> tin to brittle, alpha-modification grey tin. Eventually it decomposes into
> powder,
> hence the name tin pest.
These phase changes are called allotropes.
> > The decomposition will catalyze itself, which is why the reaction seems to
> > speed up once it starts; the mere presence of tin pest leads to more tin
> pest.
> > Tin objects at low temperatures will simply disintegrate. "
> > http://en.wikipedia.org/wiki/Tin_pest
>
>
> In the situation where you can just pull a component from a board, not
> desoledered, it is sometimes possible to see a grey powdery surface to the
> component, suggestive of tin-pest.
No surprise. A guitar amp kept in the garage will see those temps.
> And for using tin tinned new RoHS components destined for both old boards
> and Pb-Sn solder or new boards and silver solder, burr the tin off with a
> "diamond" cintride burr on a Dremmel, before tinning with the intended
> solder. A solid layer of tin is asking for trouble - turn to dust tin-pest.
And whiskers.
The military etc are doing an enhanced version of what you describe.
Graham
N Cook
Its a time-temp-effect thing, must be less than 13.2 C to make any
appearance but
"As temperatures decrease below 13.2oC, the shift from the metallic
allotrope to the non-metallic allotrope progresses, reaching a maximum at
about -30oC (-22oF)."
http://dwb.unl.edu/Teacher/NSF/C10/C10Links/Chemistry.about.com/library/week
ly/aa040300a.htm
Eeyore
N Cook wrote:
> I'm not sure the critical temp is 13 deg C, has someone confused 13 deg F
> and 13 deg C?. 13 degree C is quite a normal unheated room temperature.
No, it IS 13.2C.
http://ap.pennnet.com/articles/article_display.cfm?article_id=279192
No idea how much the alloying helps. But it will do a bit.
Graham
Eeyore
N Cook wrote:
> I'm not sure the critical temp is 13 deg C, has someone confused 13 deg F
> and 13 deg C?. 13 degree C is quite a normal unheated room temperature.
Also see .....
http://findarticles.com/p/articles/mi_qa5348/is_200106/ai_n21473892
Which covers the popular manufacturing formula including 0.5% Cu.
Graham
Eeyore
N Cook wrote:
> Its a time-temp-effect thing, must be less than 13.2 C to make any
> appearance
How cold does the electronics in your car get in winter ?
Graham
N Cook
Here is a pic I took of what was probably tin pest.
Ignore the top pic as just a control showing normal silvery appearance of
pins after desoldering.
http://home.graffiti.net/diverse:graffiti.net/solder.jpg
The black cap, the top pin could be pulled out and the bottom one needed
desoldering. It is just about possible to see the all grey dusty covering to
the top pin. So that 100 percent tin layer eventually turns to the grey form
, expanding in the process. So like a weed growing through concrete it
forces the solder apart as well as in itself being non-condusctive.
N_Cook
Do you know of a precise term, military or civil, for the process of
mechanical (or other method) removal of full tin tinning of component legs,
prior to use ?
With that pic of tin-pested cap I should have said that the solder joints
otherwise looked normal, only this surface layer tinning of the pin had
transformed to grey.
Arfa Daily
Oh I had to work on them too ! Our company was responsible for background
music machines that were rented out ro shops etc. They used a sort of
cassette tape that was endless (!) in that it wound off the centre and back
on to the outside. Bit like an 8 track mechanism, but only had four tracks,
as I recall. Anyways, they had a bloody great amplifier built into them,
based on 2N3055s. Being an early design, there was no protection or bias
stabilization, and you only had to bring a 20k / volt meter near to some
points to get them to run away, releasing their magic smoke ... Happy days.
It's back when engineers learnt the business properly d:~}
Arfa
Arfa Daily
No problem Jim, and it's nice to know that there are still people out there
honest enough to admit to such a situation ! I would be interested to know
what your friend's findings have been. If you once start working with
lead-free, you won't mistake it for leaded again ! The first thing you will
notice is why you suddenly don't seem able to make a shiny 'good' looking
joint any more. The stuff is also a lot 'stiffer' as it comes off the reel.
You might be surprised just how unpleasant the the stuff is to work with,
compared to 'proper' solder - and that goes for the aggressive flux fumes as
well. I wonder if your friend's place have put in additional bench
extraction / ventilation to ensure that he doesn't breath the stuff ...
Arfa
N Cook
I see that in that article
Tin pest in Sn-0.5 wt.% Cu lead-free solder
Sliver solder does not supress tinpest, very much reduces its growth, but
not supressed like leaded solder.