Acceptable via sizes on PCBs.
Russ LeMaster
I am currently working on a PCB layout right now and am doing manual
routing. I am probably going to get the board made at one of the less
expensive overseas board houses like pcb-pool or a similiar company.
In viewing the requirements for these sites, one things seems to be
missing and I'm wondering if it is because it doesn't matter or if it
is just something that is very standard and is left out.
My question is, what are the acceptable sizes for vias on a PCB
design. I am using Eagle and the default is .040" with a .032" hole. I
would like to go as small as a .024" with .016" hole. Is this
something that would cause board makers a problem?
Also, what is the actual minimum sizes that most (prototype oriented)
board houses generally stick to.
Thanks,
Russ
tus...@my-deja.com
> My question is, what are the acceptable sizes for vias on a PCB
> design. I am using Eagle and the default is .040" with a .032" hole. I
> would like to go as small as a .024" with .016" hole. Is this
> something that would cause board makers a problem?
>
> Also, what is the actual minimum sizes that most (prototype oriented)
> board houses generally stick to.
The minimum via size which factory can produce depend on the minimum
drill hole size and the minimum annual ring which can be produced.
For instance if the minimum drill hole is 0,6 mm (24 mils) and the
minimum tracks/spaces are 0,2 mm (8 mils) then the minimum via is 24+8+8
= 40 mils.
Cheers
Tsvetan
----
PCB prototypes for $26 at http://run.to/pcb
Sent via Deja.com http://www.deja.com/
Before you buy.
John Larkin
<rlem...@bellsouth.net> wrote:
>Hi,
>
>I am currently working on a PCB layout right now and am doing manual
>routing. I am probably going to get the board made at one of the less
>expensive overseas board houses like pcb-pool or a similiar company.
>
>In viewing the requirements for these sites, one things seems to be
>missing and I'm wondering if it is because it doesn't matter or if it
>is just something that is very standard and is left out.
>
>My question is, what are the acceptable sizes for vias on a PCB
>design. I am using Eagle and the default is .040" with a .032" hole. I
>would like to go as small as a .024" with .016" hole. Is this
>something that would cause board makers a problem?
>
>Also, what is the actual minimum sizes that most (prototype oriented)
>board houses generally stick to.
>
>Thanks,
>Russ
>
Most US board houses will do a 16 mil drill, but probably prefer a bit
more annular ring, maybe 28 mil pad OD. Some board houses go a lot
smaller, but it's expensive.
John
Russ.Shaw
be less than about 5:1 so that the thru-hole plating is reliable.
tus...@my-deja.com wrote:
>
> > My question is, what are the acceptable sizes for vias on a PCB
> > design. I am using Eagle and the default is .040" with a .032" hole. I
> > would like to go as small as a .024" with .016" hole. Is this
> > something that would cause board makers a problem?
> >
> > Also, what is the actual minimum sizes that most (prototype oriented)
> > board houses generally stick to.
>
> The minimum via size which factory can produce depend on the minimum
> drill hole size and the minimum annual ring which can be produced.
> For instance if the minimum drill hole is 0,6 mm (24 mils) and the
> minimum tracks/spaces are 0,2 mm (8 mils) then the minimum via is 24+8+8
> = 40 mils.
>
--
*******************************************
* Russell Shaw, B.Eng, M.Eng(Research) *
* email: rus...@webaxs.net *
* Australia *
*******************************************
Randy Barrow
>
> Hi,
>
> I am currently working on a PCB layout right now and am doing manual
> routing. I am probably going to get the board made at one of the less
> expensive overseas board houses like pcb-pool or a similiar company.
>
> In viewing the requirements for these sites, one things seems to be
> missing and I'm wondering if it is because it doesn't matter or if it
> is just something that is very standard and is left out.
>
> design. I am using Eagle and the default is .040" with a .032" hole. I
> would like to go as small as a .024" with .016" hole. Is this
> something that would cause board makers a problem?
>
> Also, what is the actual minimum sizes that most (prototype oriented)
> board houses generally stick to.
>
Hi Russ-
The problem you may run into is not the size so much as the mechanical
slop factor of their machining process. If the drilling is not really
accurate over a certain distance, you can end up with an off-center hole
through the via's edge. Murphy's law dictates that it will be on the
edge where the connecting trace WOULD HAVE tied into the via. Further,
this will tend to occur where the fault will be hidden under difficult
to remove components (i.e. multi-leaded SMD components with very high
pin counts). The real problem occurs when these off-center drillings
don't quite cut all the way through the trace, but leave a little
whisker, and that doesn't fail in production test. ;->
It only fails when you've delivered the product just days short of a
forfeiture deadline ("deliver the goods on time or you eat the whole
order"), the customer accepts delivery and they start to fail a couple
of days into deployment, due to a small amount of flexing or thermal
expansion or "phase-of-the-moon". The point is, stuff like this *can*
happen when you least expect it to. So, given the choice, I'd always opt
for larger vias when possible. You can always tighten up on your
pad-to-trace and trace-to-trace clearances. These clearance limits are
absolute, and do not depend on the "relative" accuracy of their
drilling.
We have for years used 0.050" pads with 0.024" holes for power and
ground trace vias. For signal traces, an 0.030" pad with an 0.018" hole
seems to work just fine, and is within the tolerances of our "on-shore"
PCB houses. We run 0.008" traces on 0.008" clearance with no problems,
and no extra "fine-line" charges.
I'd personally recommend Advanced Circuits for your prototypes and
possibly production, depending on your quantities.
http://www.4pcb.com
http://www.4pcb.com/capabilities.htm (tolerances info)
Good Luck,
Randy Barrow
--
==============================================
Please remove NOSPAM from address for replies
==============================================
Russ LeMaster
Thanks for the tips. I had not considered the offset drilling problem.
I checked out Advanced Circuits web page, and unfortunately the don't even
come close to the price range I'm working within. This is for a hobby based
robotics controller board, and the budget for it is definitely on a hobby
level. :)
Their cheapest board (ie: via an example price quotation) for a 3" x 4"
board is $74.00 and that is with no SMD parts. This is also for a 5 (I
think) board quantity.
Some one like pcb-pool, on the other hand, can do the same board in
quantities of 1 for $22.50.
Thanks,
Russ
George H. Patrick, III
> Hi,
>
> I am currently working on a PCB layout right now and am doing manual
> routing. I am probably going to get the board made at one of the less
> expensive overseas board houses like pcb-pool or a similiar company.
>
> In viewing the requirements for these sites, one things seems to be
> missing and I'm wondering if it is because it doesn't matter or if it
> is just something that is very standard and is left out.
>
> My question is, what are the acceptable sizes for vias on a PCB
> design. I am using Eagle and the default is .040" with a .032" hole. I
> would like to go as small as a .024" with .016" hole. Is this
> something that would cause board makers a problem?
>
> Also, what is the actual minimum sizes that most (prototype oriented)
> board houses generally stick to.
>
> Thanks,
> Russ
It depends on the manufacturer, but that value is fairly common
for better quality US houses. You should be concerned
"breakout" conditions (where the drill will wander from the
center of the pad and cut into the connecting trace) with
less expensive board houses -- place another (smaller) pad
without a drill over the junction of the trace and via (also
commonly called a snow-man pad because of it's appearance) , or
use additional copper fill to fillet the trace into the pad to
minimize the effects of this.
--
+--------------------------------+----------------------------------+
| George H. Patrick, III | Resources for PCB Designers on |
| gpat...@aracnet.com | the Web - The Designer's Den |
| George.H...@tektronix.com | http://www.aracnet.com/~gpatrick |
+--------------------------------+----------------------------------+
| Take what you like and leave the rest... My opinion ONLY. |
+-------------------------------------------------------------------+
Randy Barrow
>
> Hi Randy,
>
> Thanks for the tips. I had not considered the offset drilling problem.
>
> I checked out Advanced Circuits web page, and unfortunately the don't even
> come close to the price range I'm working within. This is for a hobby based
> robotics controller board, and the budget for it is definitely on a hobby
> level. :)
>
> Their cheapest board (ie: via an example price quotation) for a 3" x 4"
> board is $74.00 and that is with no SMD parts. This is also for a 5 (I
> think) board quantity.
>
> Some one like pcb-pool, on the other hand, can do the same board in
> quantities of 1 for $22.50.
>
Hi Russ-
Assuming you go with pcb-pool, I was just curious about whether your
price quotation includes the *import duty* on merchandise from either
Germany or Ireland. Do they have a US based facility that is not
mentioned on the websites that I visited?
In addition, Advanced Circuits at production quantity compares quite
favorably to your pcb-pool pricing. Say 100 pcs at 4 weeks with 50 SMD
pads on each side is only around $5.50 a piece plus $1.35 amortized NRE
per board. So $6.85 is not that bad in comparison. Now, if you add 100%
ET to the mix that adds about $630 to the bill. So now your A.C.P.B.
(amortized cost per board) is up to ($630/100) +($135/100) + 5.50 =
$13.15, but you do have a 100% tested board. I'd be curious to see what
pcb-pool adds for their ET.
There's a great sign I've seen over the years in the PCB game that goes
something like this: FAST - CHEAP - GOOD --- pick any two! ;->
Later,
Randy
Russ.Shaw
pads at the last step.
> --
>
> ==============================================
> Please remove NOSPAM from address for replies
> ==============================================
--
Ken
"Russ.Shaw" wrote:
>
> The way to stop off-center breakage problems is to tear-drop the
> pads at the last step.
That is not a gauranteed fix. What if the hole offset is in the opposite
direction from the tail of the teardrop ?
--
Ken Tyler - 1400+ POV-Ray, Graphics, 3D Rendering, and Raytracing Links:
http://home.pacbell.net/tylereng/index.html http://www.povray.org/links/
Russ LeMaster
I haven't checked export taxes, but shipping is of no consequence since I get a
"substantial" discount through FedEx (a benefit...:) I will definitely check on
the tax issue.
The deal is, they sell in 1 board quantities for this price. This is a one time
type thing (or atleast at first) so there would be a substantial cost hit from
them.
If I'm not mistaken, a single 2 sided board allowing down to 8mil traces runs
around $22.50 and I think that in order to have an ET done on it it is an
additional 25 Eurodollars (I think, I didn't recognize the currency symbol).
Thankfully, they have a corrency converter on their web site.
If I ever decide to do a group by kinda thing (or actually start selling the
board) then I would definitely look into someone like AC.
Thanks,
Russ
Randy Barrow wrote:
Russ.Shaw
so contact is not lost.
--
Nial Stewart
>
> Hi Randy,
>
> Thanks for the tips. I had not considered the offset drilling problem.
>
> I checked out Advanced Circuits web page, and unfortunately the don't even
> come close to the price range I'm working within. This is for a hobby based
> robotics controller board, and the budget for it is definitely on a hobby
> level. :)
>
> Their cheapest board (ie: via an example price quotation) for a 3" x 4"
> board is $74.00 and that is with no SMD parts. This is also for a 5 (I
> think) board quantity.
>
> Some one like pcb-pool, on the other hand, can do the same board in
> quantities of 1 for $22.50.
>
> Russ
Russ,
I've used PCB-pool twice and am _very_ happy with the quality of the
boards I got. I used their smallest hole size for prototype (16 mil) and
fairly small pads, I can't remember the diameter but I've an idea I left
8 mil round the hole so they would have been 32mil. I carefully
checked the board and none of the via holes had wandered anywhere
near breaking the track.
Having said that, are you sure about your prices?
The smallest size they bill for is 10cmx10cm for which they
charge 30.63 Irish Pounds. The currency converter gives this as
35.29 US dollars (plus shipping).
Nial.
Johan
It si probably no problems for the board factory to manufacure the board
with the via size you want.
If you contact the board house for there "Design Rouls", then you know how
small the vias can be and all the other measurments on the bord.
/Johan Javinder
MCM-Designer
Russ LeMaster
Nial Stewart wrote:
> > Some one like pcb-pool, on the other hand, can do the same board in
> > quantities of 1 for $22.50.
> >
> > Thanks,
> > Russ
>
> Having said that, are you sure about your prices?
>
> The smallest size they bill for is 10cmx10cm for which they
> charge 30.63 Irish Pounds. The currency converter gives this as
> 35.29 US dollars (plus shipping).
Check out hte following web site: http://www.pcb-pool.com/uk_index.htm
I'm not sure what the symbol for the 49 means (German Marks?) but when I
go to their currency converter (and assuming the default in the from field is
whatever that
symbol is) it comes out to aroun $22.50 for the board advertised here. Granted,
mine will be a bit larger so it will run me more, but that is where I got the
$22.50 figure from.
Let me know if I'm wrong about the symbol... as this would certainly effect the
conversion.
Thanks,
Russ
>
> Nial.
Russ LeMaster
I looked at their design rules, but nothing was said about vias. However, as I
have recently learned, the reason is that they do state the minimum drill size
(which is 16mil for the doublesided board) then you can calculate the via from
that and their minimum track size (8mil). Therefore, as pointed out, the
smallest via I can get "reliably" is .032"/.016".
Thanks,
Russ
tusunov
http://www.pcb-pool.com/uk_index.htm
>I'm not sure what the symbol for the 49 means (German Marks?)
but when I
>go to their currency converter (and assuming the default in the
from field is
>whatever that
>symbol is) it comes out to aroun $22.50 for the board advertised
here. Granted,
>mine will be a bit larger so it will run me more, but that is
where I got the
>$22.50 figure from.
>
>Let me know if I'm wrong about the symbol... as this would
certainly effect the
>conversion.
you are defenitely wrong.
the price is 49 GBP
if you want to check the DEM prices you had to open the Germany
language version. If I remember it's 99 DEM.
Tsvetan
---
PCB prototypes for $26 at http://run.to/pcb
-----------------------------------------------------------
Got questions? Get answers over the phone at Keen.com.
Up to 100 minutes free!
http://www.keen.com
Russ LeMaster
Thanks for the info.
By the way, I originally planned on going with your boards, but as I
remember the drill size restrictions were too large. This isn't a
problem with thru-holes for components, but it forces me to increas
the size of the vias.. right? That would cause a major headache. In
looking at your site now, it looks like the smallest standard drill
size is .028" , I know I can pay a bit extra for non-standard tool
sizes, but what is the smallest drill size you can do?
Thanks,
Russ
Russ LeMaster
I did a search on the symbol their pricing is in "the C with two
horizontal lines in it" and this is a Euro Dollar symbol. According to
all the universal conversion I've checked, their 49 Euro card comes
out to be 44 US Dollars. Still more than your $26 dollar board, but
with .016" drill sizes. Also for their four layer boards, they offer
.012" drill sizes and 6mil track width/spacing. Do you guys intend to
offer anything competitive with this in the future?
Thanks,
Russ
Randy Barrow
>
> Hi,
>
> I did a search on the symbol their pricing is in "the C with two
> horizontal lines in it" and this is a Euro Dollar symbol. According to
> all the universal conversion I've checked, their 49 Euro card comes
> out to be 44 US Dollars. Still more than your $26 dollar board, but
Gee Russ, looks like there might be a "little" difference in that
"bargain" price of $22.50USD. And then you have import duties, which for
a non-NAFTA outfit could add up. Have fun, but *watch* your wallet. Some
bargains cost more than they appear. Remember: FAST - CHEAP - GOOD -
pick any two! ;-)
Later,
Randy Barrow
P.S. I forget the name, but isn't there some "el-cheapo" joint in
Canada? Alberta, if I'm thinking of the right place. Hey, it's a NAFTA
gig so maybe they're cheaper than your "pool bargain" and almost as good
quality as Advanced Circuits...just a thought.
Russ LeMaster
Does anyone know of the canada outfit? I'm all for finding the best way to
do things (and not pay a fortune for one or two boards).
Thanks,
Russ
Boris Mohar
<rlem...@bellsouth.net> wrote:
>Hi Randy,
>
>Does anyone know of the canada outfit? I'm all for finding the best way to
>do things (and not pay a fortune for one or two boards).
>
>Thanks,
>Russ
>
>
www.apcircuits.com
www.apcircuits.org
www.apcircuits.net
Regards,
Boris Mohar
Viatrack Printed Circuit Designs
Nial Stewart
>
> Hi Randy,
>
> Does anyone know of the canada outfit? I'm all for finding the best way to
> do things (and not pay a fortune for one or two boards).
>
> Thanks,
> Russ
I've used them too :-).
The boards were expensive for me 'cos they charged me premium rates
for couriering them to Belfast.
I think it came out at 100 Pounds Sterling for two boards (10cm X 8 cm)
with no solder mask).
Their quality was good too.
Nial.
Nial Stewart
>
> Ni Nial,
> Check out hte following web site: http://www.pcb-pool.com/uk_index.htm
> I'm not sure what the symbol for the 49 means
It's Irish Pounds, I got stung by that for my first order, still good
value
though.
Bear in mind that this is for a PCb that's 10cm x 16 cm, and you said
you
wanted 3"x4" which would be charged at the minimum size of 10cm X 10cm.
> (German Marks?) but when I
> go to their currency converter (and assuming the default in the from field is
> whatever that
> symbol is) it comes out to aroun $22.50 for the board advertised here. Granted,
> mine will be a bit larger so it will run me more, but that is where I got the
> $22.50 figure from.
http://www.pcb-pool.com/html_uk/uk_angebot_2.htm
Gives you a more detailed price breakdown.
If you plug in 30.63 irish pounds and you get 35 dolloars, although this
is
withought silk screen.
>
> Let me know if I'm wrong about the symbol... as this would certainly effect the
> conversion.
>
> Thanks,
> Russ
Nial.
tus...@my-deja.com
> Hi Tusunov,
Hi,
BTW my name is Tsvetan :)
> By the way, I originally planned on going with your boards, but as I
> remember the drill size restrictions were too large. This isn't a
> problem with thru-holes for components, but it forces me to increas
> the size of the vias.. right? That would cause a major headache. In
> looking at your site now, it looks like the smallest standard drill
> size is .028" , I know I can pay a bit extra for non-standard tool
> sizes, but what is the smallest drill size you can do?
0,6 mm (24 mils)
The smallest drill size depend mostly of two major factors: drilling
equipment and plating equipment.
We can drill down to 0,5 mm (20 mils), but our plating equipment doesn't
give satisfactory results, so we have restricted to 0,6 mm (24 mils) the
min.drill size we accept. BTW the finished hole size is +0,1mm due to
the plating i.e. your resulting hole is 0,5 mm (20 mils).
Some board shops quote the finished hole size and increase the drill
size +0,1mm without leting you know.
Tsvetan
----
PCB prototypes for $26 at http://run.to/pcb
tus...@my-deja.com
> I did a search on the symbol their pricing is in "the C with two
> horizontal lines in it" and this is a Euro Dollar symbol. According to
> all the universal conversion I've checked, their 49 Euro card comes
> out to be 44 US Dollars. Still more than your $26 dollar board, but
With double solder mask and silkscreen component mark our $26 protos are
best value. I personally never have been seen offer to come even close
to double our price.
Unfortunately this is also an problem as many customers can't believe
that QUALITY product can be produced for such low cost and assume that
we may use junk materials or so on. I even found one funny message on
the Internet of guy which assume that to be produced PCBs at those
prices we have to use slavery labour :)))
Nobody take into account that in the prototypes the material cost is
less than 10% of the value. Why else your local PCB manufacturer can
produce your boards for $2 per sq. decimener in vloume? Everything above
those $2 is just LABOUR seting up machines, ploting files etc.
>Also for their four layer boards, they offer
> .012" drill sizes and 6mil track width/spacing. Do you guys intend to
> offer anything competitive with this in the future?
Well that's something probably we'll do in the future.
Altrough we are producing PCBs from 1991 our major output still is
SINGLE side PCB :) in volume for the consumer industry.
The double side PCB volumes are 10% of our output.
We started our proto business at the end of 1999 and the protos are less
than 1% of our output.
To reach 0,3 mm we'll need laser driller and Pulse plating equipment
which is serious investment.
tus...@my-deja.com
> > I did a search on the symbol their pricing is in "the C with two
> > horizontal lines in it" and this is a Euro Dollar symbol. According
to
> > all the universal conversion I've checked, their 49 Euro card comes
> > out to be 44 US Dollars. Still more than your $26 dollar board, but
>
> Gee Russ, looks like there might be a "little" difference in that
> "bargain" price of $22.50USD. And then you have import duties, which
for
> a non-NAFTA outfit could add up. Have fun, but *watch* your wallet.
Some
> bargains cost more than they appear. Remember: FAST - CHEAP - GOOD -
> pick any two! ;-)
The PCB from Bulgarian origin enter with 0% import tax to EC and USA.
So you have to pay the price of PCB and the price for the transport - no
other hidden charges, duties, and so on.
Russ LeMaster
On your order(s) from pcb-pool (assuming you are in the us?) what kind of taxes,
etc. were you charged?
Thanks,
Russ
Russ LeMaster
I'm definitely not ruling you guys out on the basis of quality as I have no
reason to beleive you produce bad quality boards. The price is definitely
something that attracted me to your company, but having to produce via sizes
of .040" or more due to drill sizes means major revamping in my current
design. I may still take this route since, as I said, I like your prices.
Any idea when the 4 layer boards will start and approximate pricing?
Thanks,
Russ
tus...@my-deja.com wrote:
> > I did a search on the symbol their pricing is in "the C with two
> > horizontal lines in it" and this is a Euro Dollar symbol. According to
> > all the universal conversion I've checked, their 49 Euro card comes
> > out to be 44 US Dollars. Still more than your $26 dollar board, but
> > with .016" drill sizes.
>
> With double solder mask and silkscreen component mark our $26 protos are
> best value. I personally never have been seen offer to come even close
> to double our price.
> Unfortunately this is also an problem as many customers can't believe
> that QUALITY product can be produced for such low cost and assume that
> we may use junk materials or so on. I even found one funny message on
> the Internet of guy which assume that to be produced PCBs at those
> prices we have to use slavery labour :)))
> Nobody take into account that in the prototypes the material cost is
> less than 10% of the value. Why else your local PCB manufacturer can
> produce your boards for $2 per sq. decimener in vloume? Everything above
> those $2 is just LABOUR seting up machines, ploting files etc.
>
> >Also for their four layer boards, they offer
> > .012" drill sizes and 6mil track width/spacing. Do you guys intend to
> > offer anything competitive with this in the future?
>
> Well that's something probably we'll do in the future.
> Altrough we are producing PCBs from 1991 our major output still is
> SINGLE side PCB :) in volume for the consumer industry.
> The double side PCB volumes are 10% of our output.
> We started our proto business at the end of 1999 and the protos are less
> than 1% of our output.
>
> To reach 0,3 mm we'll need laser driller and Pulse plating equipment
> which is serious investment.
>
Russ LeMaster
Sorry about the name thing. :)
Thanks for the details. Depending on how things go in my searches for low
priced prototype boards, I may be forced to use larger vias (this will be a
pain since it makes routing that much tougher).
Thanks,
Russ
tus...@my-deja.com wrote:
Ken
tus...@my-deja.com wrote:
> To reach 0,3 mm we'll need laser driller and Pulse plating equipment
> which is serious investment.
Monday I got to see some laser drilled 4 layer panels with .006, .004,
and .002 inch holes drilled into them. Friday I get to try to plate
them without pulse plating equipment. I am reasonably confident I can
get them to plate ok but I may have to use a few tricks to succeed.
Russ.Shaw
tus...@my-deja.com wrote:
>
> To reach 0,3 mm we'll need laser driller and Pulse plating equipment
> which is serious investment.
>
> Tsvetan
> ----
> PCB prototypes for $26 at http://run.to/pcb
>
> Sent via Deja.com http://www.deja.com/
> Before you buy.
--
Nial Stewart
>
> Hi Nial,
>
> On your order(s) from pcb-pool (assuming you are in the us?) what kind of taxes,
> etc. were you charged?
> > The boards were expensive for me 'cos they charged me premium rates
> > for couriering them to Belfast.
^^^^^^^^
Ie N. Ireland. I don't know what sort of taxes you guys get hit with,
I don't think I had to pay any sort of inport tax for the boards coming
from AP Circuits in Canada.
Nial.
Nial Stewart
>
> Hi,
>
> I'm definitely not ruling you guys out on the basis of quality as I have no
> reason to beleive you produce bad quality boards. The price is definitely
> something that attracted me to your company, but having to produce via sizes
> of .040" or more due to drill sizes means major revamping in my current
> design. I may still take this route since, as I said, I like your prices.
>
> Any idea when the 4 layer boards will start and approximate pricing?
>
> Thanks,
> Russ
This was also the main reason I went with PCB Pool. I tend to route
power, ground and any sensitive tracks myself then auto-route the rest.
Having the smaller vias seems to make the auto-routers job a fair bit
easier.
I would have liked double sided solder mask and component marking
included
in the price (I had to pay extra for solder mask with PCB Pool).
Nial.
tus...@my-deja.com
> Monday I got to see some laser drilled 4 layer panels with .006, .004,
> and .002 inch holes drilled into them. Friday I get to try to plate
> them without pulse plating equipment. I am reasonably confident I can
> get them to plate ok but I may have to use a few tricks to succeed.
>
And what is your laminate overall thickness? I.e. what is hole/depth
ratio?
For 2 mils HOLE you couldn't do any electroplating and probably the
process should be only chemical with all disadvantages involved.
Anyway it would be very ineteresting to me to learn what are the results
and what is your overal yield.
tus...@my-deja.com
> How is pulse-plating done?
>
As the normal electrochemical plating, but there are short high
current pulses with changed polarity .
To reverse the polarity may seems non sense as the process reverses i.e.
you disolve the cupper from the object (of course for very small amount
of time), but this leads to more even and controlled plating process.
The normal plating process plate more the top and bottom of the vias and
go thiner in the middle of the vias - this is pretty bad for vias with
big depth/hole ratio. With reverse pulse plating the plating thickness
is more even and higher dept/hole ratios can be achieved.
Ken
tus...@my-deja.com wrote:
>
> > Monday I got to see some laser drilled 4 layer panels with .006, .004,
> > and .002 inch holes drilled into them. Friday I get to try to plate
> > them without pulse plating equipment. I am reasonably confident I can
> > get them to plate ok but I may have to use a few tricks to succeed.
> >
>
> And what is your laminate overall thickness? I.e. what is hole/depth
> ratio?
The aspect ration will be about 5.5:1 with a plating thickness requirement
of about .0005-.0009.
> For 2 mils HOLE you couldn't do any electroplating and probably the
> process should be only chemical with all disadvantages involved.
I have been successfully plating 8 mil holes with a high yeild using
a standard acid copper plating bath. I am concerned about air entrapment
more than anything else with the smaller hole sizes but we have a
very effecient tank set up with high pressure dispersion pumps and
sophisticated vibrating mechanical racks to help dislodge both air
and excess hydrogen that builds up during the plating process. Even
if the vias close up during the plating process we don't care as long
as we get a good connection to the internal layers.
> Anyway it would be very ineteresting to me to learn what are the results
> and what is your overal yield.
I won't know until I try. Frankly I too am skeptical but I was also
skeptical about my ability to get reliable results with 8 mil holes.