Rudy,
    Your description is very accurate.  If the boards are more than 2 
minutes old, you need to use a preclean solution of 50% cheap orange juice 
mixed with 50% battery acid.  I would also recommend a nitrogen atmosphere 
for the board designer.
     Seriously though, we have a Duroid board here that has the same finish 
requirement.  I've been told because of dimensional instability concerns it 
should not be HASL'd.  The concern included possible fracturing of the 
plated through holes.
     We are presently considering converting this board to Ni/Au.

                Norm Dill
 ----------
From: [log in to unmask]
To: [log in to unmask]
Subject: Unfused Solder and/or Tin
Date: Thursday, October 17, 1996 12:18PM

Recently had occaision to have some problems associated with recovering
scrapped PCB's that have as final finish UNFUSED plated Tin or Solder 
(wasn't
sure which).  Is there anyone who can enlighten me as to why an
assembler/user would want such a finish.  The finish oxidizes heavily, and
quickly, and I suspect likely needs to be cleaned immediately before
soldering, or alternately requires a flux so active that it will etch the
substrate if not washed off in a few minutes....

Other than that, it is likely wonderful??

Can anyone help me understand this strange (to me) finish?

Rudy Sedlak

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