SMT rework
Herman
I like the idea of the vacuum pencil and the hot tweezers. What would be
the recommended tips for general use for ICs and resistors etc. I do not
need to do the PLLC size chips. Price $300 max or so.
Arfa Daily
"Herman" <ri...@bellsouth.net> wrote in message
news:i32fmn$iu8$1...@news.albasani.net...
I have recently purchased a hot air rework station. It has hot air handpiece
with fully controllable airflow and temperature. Digital readout for temp.
Also has conventional iron with stand, again fully controllable temp and
digital readout. Comes with 5 round hot air nozzles. Square ones for QFPs
etc purchased from other sources fit, I understand from a friend who also
has one. Also 5 tips for the soldering iron, spare element for the hot air
and spare element for the soldering iron. I paid 55UKP for it, so work that
out in USD - about $80 maybe. Company I got it from is in China and called
dragondirectmall. Very efficient and helpful service. Once it had been
collected from them by DHL, arrived at my door less than 24 Hrs later. On
their eBay site, they have a video showing a station being built, and you
can see that for the money, it is incredible value.
Go to eBay and put in "KADA 852D" then look for the one that says "buy now
for £55". They have USD prices as well, as far as I recall. Very satisfied
with mine, so far.
Arfa
Herman
"Arfa Daily" <arfa....@ntlworld.com> wrote in message
news:FBh5o.37277$gM.26872@hurricane...
I was looking at that one. What do you think about the vacuum pencil and
the hot tweezers? Seems like a good idea for resistors and diodes. Do the
tips supplied work for small ICs? I have never used one of these stations.
Arfa Daily
"Herman" <ri...@bellsouth.net> wrote in message
news:i393ul$gdd$1...@news.albasani.net...
I've never bothered with vacuum pencils and hot tweezers. I guess it depends
how much you are going to be doing with it. I work with surface mount on a
daily basis, but it's actually pretty reliable stuff, in general. When I
need to get a resistor off a board, I just heat both ends alternately with a
standard iron, and then 'flick' it off the pads. If I have one that is in an
awkward place to do that, I use one of the shaped bits that I have for my
Antex station. These are just 'standard' tips in that they fit any Antex 25
watt iron, but have a sort of 'forked' tip, the prongs being the right
distance apart to heat both ends simultaneously, of standard profile sm
components. There are also tips in the same range that have an I.C. spacing
to the forks, and are the length of an IC. Good for your standard sized 8 /
14 / 24 etc pinned sm ICs. I have a full set of these specially shaped tips
that I use when needed with my Antex temp controlled station. Not cheap, but
a good investment. As for picking the devices up, I just use needle tipped
stainless steel tweezers.
The smallest nozzle supplied for the hot air handpiece is a couple of mm
diameter. It easily allows removal of ICs as long as they are not too big.
The process involves going round and round the pin rows until it's hot
enough for the solder on all pins to stay molten long enough to flick the IC
off the board. Obviously, if it's a very big QFP package, then that's not so
easy to do, and a shaped nozzle to heat all four sides at once, is more
appropriate.
That said, when I got my KADA hot air station, I spent a while getting a
'feel' for it, and I removed all sizes of QFP ICs from and old mother board,
and just to prove that you could, I even removed two BGAs that were probably
4cm square each.
I guess it's horses for courses, but for general use, so far, I can
thoroughly recommend my KADA as being a good value for money tool, and
actually, of remarkable quality and functionality, for the price.
Arfa
stra...@yahoo.com
<snip>
> I was looking at that one. What do you think about the vacuum
pencil and
> the hot tweezers? Seems like a good idea for resistors and diodes.
Do the
> tips supplied work for small ICs? I have never used one of these
stations.
A couple weeks back we had to transplant a pair of 100 pin QFP chips
on an old Sony broadcast VTR. To remove them we used an Ungar hot air
gun like you'd use for heat shrink. To replace them we used a Metcal
STTC-126 tip and over-soldered and cleaned up with solder wick
followed by flux removal. These were not high density pins but I have
used this technique on 0.5 mm pin spacing. Personally I find a Metcal
soldering iron a far more useful tool.
G²
Jim Yanik
I've used the Pace thermo-tweeze system,at Tektronix.It's nice,but the tips
for the many types of ICs gets costly.
do you use a hot plate [or other pre-heat] for pre-heat of the workpiece?
--
Jim Yanik
jyanik
at
localnet
dot com
Arfa Daily
"Jim Yanik" <jya...@abuse.gov> wrote in message
news:Xns9DC9F1B71B4D7...@216.168.3.44...
Interesting you should ask that Jim. I've just been working on some boards
where the use of hot air was the only option, but I was finding that I had
to get the areas of concern up to a very high temperature in order for the
heat that was being put in, to not be leached away by the board substrate.
So I employed a bit of lateral thinking, and knocked up a little jig to hold
the boards flat and level about 3 inches or so above the base (a piece of
MDF). I then fitted two 12v 50 watt halogen lamps - the sort fitted in
ceiling downlighters, shaped like an Apollo rocket nose cone - pointing
upwards, and under the areas of concern. I switch these on, and leave them
for about 5 minutes. When I come back, the board is toasty warm, and I am
then able to carry out the soldering work using less air and temperature. So
far, this has been 100% successful on every one that I've done.
Arfa
N_Cook
Why the intermediary MDF? I suppose it would be a useful surface to stick
some thermochromic stickers
Jim Yanik
news:i3bbhn$g50$1...@news.eternal-september.org:
> Arfa Daily <arfa....@ntlworld.com> wrote in message
> news:FG96o.40656$zT3.39612@hurricane...
>>
>>
>> "Jim Yanik" <jya...@abuse.gov> wrote in message
>> news:Xns9DC9F1B71B4D7...@216.168.3.44...
>> > I've used the Pace thermo-tweeze system,at Tektronix.It's nice,but
I believe he said the MDF was the base,the jig holds the boards
horizontally over the base,on which the halogens are mounted.
I wonder if the "jig" is a Panavise?
Arfa Daily
>>
>> Why the intermediary MDF? I suppose it would be a useful surface to
>> stick some thermochromic stickers
>>
>>
>>
>
> I believe he said the MDF was the base,the jig holds the boards
> horizontally over the base,on which the halogens are mounted.
>
> I wonder if the "jig" is a Panavise?
>
> --
> Jim Yanik
Correct, Jim. The MDF is the 'base'. The boards have mounting holes along
their edges, which take screws when they are assembled into their product.
So I took a piece of MDF, cut a base, and two pieces about 9" long by 3" or
so wide. I then screwed these to the base like a pair of 'walls', set the
right distance apart so that their centres were exactly under the mounting
holes. I then marked a couple of these holes on each side, drilled 3mm holes
down into the 'walls', and inserted cut down pieces of laser slide rails
from old CD decks. These have nice smooth chamfered ends on them as
standard. This allowed me to just drop a board over the pins, which then
served to locate it on the tops of the walls, and stop it sliding around.
The whole thing was then modified to take the lamps under the board, by
drilling two 17mm holes in the MDF base, and push-fitting circular ceramic
lampholders into those holes.
The fact that I used MDF for all this is neither here nor there really. I
just happened to have a big enough piece laying around, and it's easy to
work with. Because of the nature of its makeup, if you drill holes in it
that are just under clearance sized, it will grip whatever you push into the
hole really tightly, without it being much effort to actually push it in.
For instance, the slide rods that I used as pins, which are actually about
3.1 mm, and the lampholders which are actually a tad over 17mm diameter.
Arfa