Hi Rudy! Just a point of balance - HASL done correctly has very good
solderability retention. However, the leveling  process of blowing off the
molten solder and getting a uniform, continuous solder thickness can (and
is) a key issue in getting that solderability performance. There are
several board fabrication shops that can supply a plated tin/lead finish
that has equally good solderability retention.

Dave Hillman
Rockwell Collins
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Rudy Sedlak <[log in to unmask]> on 09/14/99 08:56:13 AM

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Subject:  Re: [TN] Surface finishing




The other big difference between Tin/Lead plating, and HASL, besides
planarity (flatness) is shelf life/solderability.

HASL is a true alloy, and has one of the better shelf lives of any surface
finish.

Tin/Lead plating is discrete crystals of Tin and Lead lying next to each
other, and the tendency for galvanic corrosion is REAL high, so the Tin
oxidizes fast, and may need to be cleaned before soldering.  And cleaning
up
Tin on a finished board is extremely difficult.

Rudy Sedlak
RD Chemical

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