Tin lead plating is just that and when fused provides a highly solderable
surface - the best ever but has a high crown down the solder termination
center line up to .003" with low plating thickness along pad edges at a
minimum of .001" making it unsuitable for most SMT applications.

HAL is hot air leveling, or HASL as hot air solder leveling. HAL/HASL is a
solder coating process applied, not electrically as solder plating, over
sometimes (nearly always) oxidized bare copper to thickness not capable of
being specified. You recognize this type coating by its uneven topography
making it often unsuitable for fine pitch SMT applications. Now, if someone
would tin lead plate followed by HASL, we'd have a much better surface -
especially if the surface conditions could be better managed.

Earl Moon
----- Original Message -----
From: Nicholas LAI <[log in to unmask]>
To: <[log in to unmask]>
Sent: Monday, September 13, 1999 5:51 PM
Subject: [TN] Surface finishing


> Hello All,
>
> What is the different of the following surface finishing.
> What is the pro and con of following surface finishing.
>
> (1) Selective Solder Plate( 60/40 Tin lead and fused)
> (2) HAL
>
> Best Regard,
> Nicholas lai
> 9/14/99
>
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