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Fri, 22 Feb 2002 11:40:35 -0700 |
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Phil,
Dealing with the "lowest bidder" will not work on this issue!
David A. Douthit
Manager
LoCan LLC
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phil bavaro wrote:
> We have used ENIG as our primary BGA board finish for many many, many
> boards built for cellular communications without issues regarding this problem.
>
> We have a major PWB fabricator telling us that they cannot control what
> appears to be a "black pad" problem and that we should be changing to
> Entek's OSP combined with a selective gold process for our standard finish.
>
> I cannot say that we have never had this problem before but usually it was
> more a case of unrinsed soldermask on a pad rather than corroded nickel
> plating beneath the gold finish.
>
> I did the cross sectioning myself and took some great pictures of the
> contaminated pad surfaces that were yielding when subjected to drop testing.
>
> I am convinced that ENIG is a solid finish but I know that it can be
> susceptible to nickel wetting problems. I have three questions:
>
> 1) What kind of frequency are the rest of you finding "black pad" to occur
> on ENIG boards?
> 2) What finish do you use for high density BGA/CSP double sided boards
> that have surface contact (gold) plating requirements?
> 3) Are any of you using underfill to hopefully negate the solder joint
> brittleness that the black pad surface inherently creates?
>
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the BODY (NOT the subject field): SIGNOFF Technet
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Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives
Please visit IPC web site http://www.ipc.org/html/forum.htm for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
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