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January 1998

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Subject:
HASL solder specs
From:
Peter Blokhuis <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Fri, 30 Jan 1998 09:08:34 EST
Content-Type:
text/plain
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text/plain (29 lines) 
Here are two problems I see with solder standards:

The most exact standard I can find is ANSI/J-STD-003 (1992) which calls out
"plus or minus 1% of nominal". (nominal being 63% tin in a 63/37 bar)  Well
what if you change your "nominal" to be a mix of 60/40 and 63/37 to follow
whatever tin concentration happens to be in your HASL pot?

Further:  the eutectic composition of tin/lead is 61.9%, which should be
optimal from a wetting perpective.  However this  'ideal' concentration is
actually out-of-
spec according to the above standard.

So: what do PCB customers actually require on a finished board?

Peter Blokhuis
Circuits DMA

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