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June 2000

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Subject:
From:
Brian Ellis <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Fri, 9 Jun 2000 11:07:17 +0300
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OK, Ralph, I may have an answer which will satisfy everybody and provide a reliable
solution. Buy some 50 micrometre rolled copper foil and have it electroplated on one
side with, say 5 um Ni and 1 um Au. This would not be expensive. Stamp out contact-size
disks. Put a drop of RMA or "no-clean" flux on the HASL contacts, place a disk onto it,
gold side out, and heat until the HASL solder melts and the disk becomes +/- integral
with the assembly. Et voila!

Heating can be via focussed IR, thermode, hot gas or even, with care, a soldering iron.

Brian

Ralph Richart wrote:

> We have answers....
>
> So I had a long talk with my customer this morning to provide input
> based on the invaluable advice from you all.
>
> I said - "is there a specific reason for choosing 3-8u" of immersion
> gold over tin/lead solder?"
> He said - "absolutely, the gold provides corrosion resistance, the gold
> does not"
> I said - "even such a thin amount - only 3-8u"?"
> He said - "definitely, all we need is the coverage, the thickness is
> irrelevant"
>
> Is this true?
>
> Needless to say, we are rebuilding the parts as we speak.  Rework sounds
> difficult to say the least, although I may try to come up with some
> scheme for fun as they have a bunch of boards that are no good right
> now.
>
> thanks for all the help.....
>
> ralph
>
> PS - more on the larrylobster story later; it's more silly than anything
> else.  Paul's poem may soon become our own, however.  Very funny!
>
> Off to build some boards....
>
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