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October 1998

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Subject:
From:
"Stephen R. Gregory" <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Mon, 26 Oct 1998 20:47:33 EST
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In a message dated 10/26/98 4:22:11 PM Pacific Standard Time,
[log in to unmask] writes:

<<    Does anyone know of a contract service that is set up to perform gold
 removal on electronic component leads?  These components include stud
 mounted transistors and other assorted transistor and IC packages.  The
 intent is to meet J-STD-001B's reqirement for gold removal, and I would
 prefer to sublet this service if possible.   It will likely entail putting
 the tinned components back into tape and reel packaging after the gold
 removal.
      Also, any comments on whether the addition of silver to Sn/Pb solders
 has any effect on gold embrittlement?
 Thanks for all responses,

 Larry Morse
 Celwave Inc.
 [log in to unmask]
  >>

Hi Larry!

    There's a company out here in Silicon Valley that I've used in the past
for pre-tinning components, and they're very good. It's a company named Six
Sigma, (phone: (408) 526-1350. It's been a few years back, but they did some
pretty difficult ceramic qfp's for me and they came out great! I was worried
that they might cause some damage or some sort of inconsistancy with the parts
that they wouldn't pass the pick and place vision when I got them back...but I
was pleasantly suprized, they all made it by the inspection camera.

    As far as tape and reeling, I'm not sure, but I don't think they actually
have tape and reel equipment themselves, but I could be wrong. Anyways,
there's enough tape and reel shops out here that if you need your parts tape
and reeled, I'm sure Six Sigma could get something worked out with someone to
get that done.

    About 2% silver solder paste...I've used it soldering to gold boards
before, and still do. I know I'm not preventing the gold from leaching, and I
know I'm not making things any stronger by doing that...but what I am doing,
is making the solder joints look a lot better. The joints come out much more
shiny that they look with a 63/37, this is no joke. Your liquidous temperature
will go down to 179 degrees C instead of 183 degrees, and I've heard that the
solder strength is somewhat reduced very, very slightly with the addition of a
silver to the alloy...but not enough to be concerned from what I understand.

-Steve Gregory-

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