Tom -

The only requirement for HASL is that it covers the entirety of the lands
and exposed copper areas. The thickness of the covering can vary from a few
tenths (or less) of a mil to more than 2mil. If you are using extremely fine
pitch components (.5mm or less) it is time to consider a better surface
finish. Silver, ENIG, white tin, and OSP all offer superior flatness to the
HASL process for fine pitch assembly. Talk to your assembly people and
decide which is best for your application and their process.

Jeffrey A. McGlaughlin CID
Sr. Designer
Battelle Memorial Institute
Columbus Ohio
[log in to unmask]



-----Original Message-----
From: Tom Parkinson - Quality System Manager - WinTronics, Inc.
[mailto:[log in to unmask]]
Sent: Monday, September 23, 2002 3:42 PM
To: [log in to unmask]
Subject: [TN] HASL


Hello all,

Have been looking for some kind of spec for HASL thickness and
uniformity. Having problems with small to fine pitch parts where HASL is
causing problems.

Only reference I can find so far is in 2221 where it says HASL is
checked not by mechanical thickness, but by the ability to solder per
JSTD003.
003 only talks about being able to solder - not about variability of
HASL causing problems.

My SMT people are giving me a hassle about the HASL......

Any suggestions??

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