This is the sort of repairs i do on my ancient tape decks,
not something i'd pay for as new board.
I'd doubt this would even pass relatively mild IPC rework/repair standards;
the training gurus must be quietly giggling somewhere, Phil?
Idea it is Brian, but the practice,
considering planarity, 100% solder underfill to prevent lifting edges, etc.
makes it dangerous and second handed technique.
I actually did it on worn through slide contacts, with thin hot jet.
The result even with jeweler's attention to amount of solder under = edge
excess
is very visible, as comparing to shaved (soft) solder to copper(burnish) and
local plate.
Be cautious Ralph, if you'd get timing or heat wrong , the base pad could
lift on you,
and than you'd start to have real problems, yours is mild so far (to much
confusion);
not digging mutilayers for inner opens yet (one day you will by the sound of
it).
pk
-----Original Message-----
From: Brian Ellis [mailto:[log in to unmask]]
Sent: Friday, 9 June 2000 18:07
To: [log in to unmask]
Subject: Re: [TN] still confused
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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