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Carlos, Clive,
I think that there is a typo involved in the original description, I would believe
it is 0.000050" of gold plating. Secondly, there should be no solder embrittlement
with a typical through-hole lead because the gold typically will not make up 3% or
more of the solder weight. and the solder forms a plug rather than just sitting atop
the SMT pad.
I am wondering why the need for the high temp solder? A specified requirement?
Since gold solders quite easily I can't picture the need for the special solder.
I have designed and sent to fab many gold plated boards in my career, they solder
wonderfully with just regular solder, typical low solids no-clean solder or aqueous
solder. So I suspect one of two problems here.
1) Moisture trapped within the PCB. Symptom, watch the hole(s) while it is being
soldered is the solder bubbling and erupting? Solution, pre-bake the PCBs to remove
trapped moisture.
2) The high temp solder is the biggest suspect. Something involved with the special
solder here, temperature, flux, some combination.
Another question. Why do you need 50 uinches of Gold? Typically this much gold is
only used on mechanical contact areas like card edge connectors. It is typically
limited to selective plating in the required areas. For regular solderable areas a
gold flash of as little as 2 - 3 uinches usually suffices very well.
Sincerely,
Brad Velander
Lead PCB Designer
Norsat International Inc.
Microwave Products
Tel (604) 292-9089 (direct line)
Fax (604) 292-9010
email: [EMAIL PROTECTED]
http://www.norsat.com
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Sent: Fri 28/02/2003 8:02 PM
To: Protel EDA Forum
Cc:
Subject: Re: [PEDA] Through hole IPC recommendations
I used HMP solder once and it seemed to have either no flux in it or the flux
burnt off very fast due to the high temps. You could try using extra flux. The
other problem is soldering to gold plating. The solder reacts to the gold and
will cause embrittlement of the joint. Im not sure the solution to that, maybe
scrap off the gold plating with a sharp blade?
BR Clive
"Carlos Claveria" <[EMAIL PROTECTED]> on 27/02/2003 09:08:34 AM
Subject: [PEDA] Through hole IPC recommendations
Hello everyone,
I was wondering if anyone could help me with this question. I built a 8
layer pcb with through hole components. I used 0.032" hole diameter and
0.050" gold plating. I have to use HMP (high melting point) solder and
found that is really hard to get a good solder flow. I was wondering if
anybody has done anything like this and what the recommended hole size
would be under these conditions.
Thanks for your help,
Carlos
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