Dear Technetters,
Instead of ENIG what should we choose? For example, for high density (with
bgas) boards with some of the components lead-free plated?
Moreover what is the choice when the components assembled to the boards are
both lead-free alloy plated and lead alloy plated (mixed)?
Regards
Sefika
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Stadem, Richard D.
Sent: Friday, May 12, 2006 11:52 PM
To: [log in to unmask]
Subject: Re: [TN] Question about ENIG in SnPb process . . . .
LOL Werner,
I totally understand where you are coming from. As a process engineer,
you should see how much hell I need to go through to verify that the
root cause of the solder reliability issues is not the process but the
pwb finish, or issues related to it. And identifying surface finish
problems is not easy, nor cheap. We usually need to go to an outside
failure analysis house to get verification. This is very costly. Thus I
also have a somewhat biased opinion towards ENIG using standard 63/37
solder. And as you pointed out, Werner, the lead-free alloys combined
with ENIG makes the situation potentially much worse.
With ENIG, some of the plating issues are exacerbated by further thermal
cycles during normal processing. This is why it is difficult to prove
"is it the plating, or is it the process". There quite often are
situations where it is a little of both.
When I am working with military hardware (or really, any electronic
assemblies), the last thing I want to take a chance on is solder
reliability issues with the board finish that go undetected until
hundreds or even thousands of assemblies are built and in the field.
Because of ENIG's fickle nature, and because I do not like to solder to
nickel for all of the reasons that are well documented here in the forum
archives and hundreds of white papers, articles, and so forth, I simply
try to stay away from it whenever possible. Why would I ever need to use
it, except for in certain situations and space applications where it is
not qualified?
And Gerard, I want you to understand I respect your knowledge and
opinions fully, I simply choose to disagree with you on this.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Werner Engelmaier
Sent: Friday, May 12, 2006 1:15 PM
To: [log in to unmask]
Subject: Re: [TN] Question about ENIG in SnPb process . . . .
Thanks Lee, Richard & Daniel,for backing up my experience.
Gerard, of course, as a consultant clients come to you when they have
problems, not when everything works as advertised. So, purely
statistically, consultants get a one-sided picture.
As a consultant, one of your first obligations is to do no harm with our
advice [sort of like physicians]-having seen what I have, there is no
way I can advise a client in favor of ENIG. Of course it works most of
the time, but God help me i advice ENIG to a client and all hell breaks
loose.
Werner
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