Proof of insufficient gold? Who needs proof? Kyocera's dimpled BGA package
drawings call out for a gold thickness of 25 microinches maximum! Don't
really know how much there is.
Jim Marsico
Senior Engineer
Production Engineering
EDO Electronics Systems Group
[log in to unmask] <mailto:[log in to unmask]>
631-595-5879
-----Original Message-----
From: Charles McMahon [SMTP:[log in to unmask]]
Sent: Wednesday, March 13, 2002 9:12 AM
To: TechNet E-Mail Forum.; Marsico, James
Subject: Re: [TN] Earls pics are up, and a question...
Jim:
Pursuant to the discussion...
Have you been able to prove that there was insufficient gold
immersion
on this board via
the first article submitted with the date code tracking from the
board
supplier?
I would feel that your theory would be substantiated with this as
your
empirical back-up.
Do you require all lots to be submitted with a sample
board/cross-section etc?
I have much interest in determining "smoking gun" flags for
de-wetting
incidences.
This appears to be an indicator does it not?
Charlie McMahon
Marsico, James wrote:
>Earl, I looked at your pictures of missing solder balls and share
your
>grief. This looks exactly what I've been seeing occasionally on
our CBGAs
>when removed from an assembly. BTW, someone on Technet had
referenced a
>paper regarding the produciblility and reliability issues of
ceramic BGAs in
>a military environment, well that was authored by yours truly.
Anyway,
>using BGAs at my company was a hard sell, but I did it. The
components we
>use aren't off-the-shelf devices, but are custom made. Every time
there was
>a component failure, it was attributed to an open BGA solder joint.
Many
>BGAs were painstakingly removed (these boards are bonded to a
rather large
>composite restraining core) and replaced. I think I still have
sort of a
>black eye for pushing the BGA technology. Occasionally our Test
Engineers
>were actually able to pin-point the exact solder joint of the
suspected
>open. Upon removal, low and behold the ball location of the open
joint
>looked exactly like your photos. All other ball locations had
remnants of
>solder. I wasn't able to do much to analyze for root cause, since,
being an
>OEM, the program management didn't want to spend money to research
the
>cause. They were happy to just replace the components. My theory?
>Insufficient gold plating protecting the Ni barrier layer, causing
the Ni to
>oxidize resulting in a marginal solder ball attachment. Nothing to
>substantiate this, just a hunch. How are you making out? Any
progress?
>
>Jim Marsico
>Senior Engineer
>Production Engineering
>EDO Electronics Systems Group
>[log in to unmask] <mailto:[log in to unmask]>
>631-595-5879
>
>
> -----Original Message-----
> From: [log in to unmask] [SMTP:[log in to unmask]]
> Sent: Tuesday, March 12, 2002 2:24 PM
> To: [log in to unmask]
> Subject: [TN] Earls pics are up, and a question...
>
> Hey all!
>
> The pictures of Earls missing balls are up! Go to:
>
> http://www.stevezeva.homestead.com
>
> ...and I have a question that's off topic here. What is a
good fluid
>to use in your printer stencil cleaner? We have a DEK 288 and we
use no
>clean paste.
>
> Thanks!
>
> -Steve Gregory-
>
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