What about the concern of tin whisker growth?  I believe that, for some
reason, it isn't an issue with the "white" tin process.  Is there published
data verifying this?  For aerospace or space applications?  What's the
difference between white tin and regular tin plating?  What makes this so
special?

Jim Marsico
Senior Engineer
Production Engineering
AIL/Electronics Systems Group
An EDO Company
[log in to unmask] <mailto:[log in to unmask]>

        -----Original Message-----
        From:   Michael Khusid [SMTP:[log in to unmask]]
        Sent:   Wednesday, February 07, 2001 11:36 AM
        To:     [log in to unmask]
        Subject:        [TN] More about white tin

        Hello everyone,

        I used white tin finish on our medium-sized board which has several
high
        count BGAs. The boards looked nice and the finish was very flat.
However,
        our assembler reported problems soldering to it, like voids in BGAs
and
        similar issues (no shorts or opens though). They also recommended
HASL as a
        preferred finish. This does not sound right to me since HASL will
not be as
        flat as white tin.

        I am thinking that they may have used wrong solder paste and/or did
not use
        enough of it. If I am on a right track, what solder paste is
preferred for
        white tin? Are there more gotchas for the white tin process? Would
other
        finishes like HASL or OSP be better for the board?

        Thanks,
        Mike Khusid

        > -----Original Message-----
        > From: DJ Robison [mailto:[log in to unmask]]
        > Sent: Tuesday, February 06, 2001 3:08 PM
        > To: [log in to unmask]
        > Subject: Re: [TN] White tin
        >
        >
        > I've used Omikrom quite a bit. I prefer it to bright acid. It
        > has better
        > coverage and is an easier process. The only negative so far
        > is that it may
        > react to some Flux's by staining.
        >
        > DJ Robison
        > Process Engineering Technician
        > TTM Technologies, Inc.
        > Redmond Division
        > 17550 NE 67th Court
        > Redmond, WA. 98052
        > (425) 883-7575 ext. 229
        > [log in to unmask]
        >
        >
        >
        > -----Original Message-----
        > From:   crbuerke [SMTP:[log in to unmask]]
        > Sent:   Tuesday, February 06, 2001 11:43 AM
        > To:     [log in to unmask]
        > Subject:        [TN] White tin
        >
        > Would like to hear about any experiences anyone has
        > with respect to the Omikron white tin immersion
        > process used on boards.
        >
        > Chuck Buerke
        > Photonics Systems
        > Toledo, Ohio
        >
        > __________________________________________________
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