hi,

there's tin-lead plate and then there is tin-lead plate and fuse.  i always
thought that the fusing process enabled the discrete particles of tin and
lead to alloy.  another advantage of the tin-lead plate and fuse is that any
dewetting and non-wetting problems stay at the fabricator's shop.

phil crepeau

-----Original Message-----
From: Rudy Sedlak [mailto:[log in to unmask]]
Sent: Tuesday, September 14, 1999 6:56 AM
To: [log in to unmask]
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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