Bruce,
Thus far, they've only been found on the top side of our products. Our
boards carry several .5 mm pitch ICs there, and yes, those are the only
locations that have been identified with this condition.
To my knowledge, all of our ICs come directly from their respective
manufacturers. In rare cases we use brokered components, but those have
been typically limited to chip resistors and caps.
Leland
-----Original Message-----
From: [log in to unmask] [mailto:[log in to unmask]]
Sent: Tuesday, May 13, 2008 11:21 AM
To: [log in to unmask]; Leland Woodall
Subject: RE: [TN] Stainless Steel Contamination Question
Leland,
You said they occur on top of the .5 mm pitch ICs. That's curious.
Are you finding them anywhere else on the board, or just at those
specific IC locations?
Is this a problem on just one side of the board?
Any chance these are broker parts and the strands are in already on the
parts? There can be all kinds of strange debris in some of that
material.
Bruce Tostevin
Benchmark Electronics
Hudson, NH
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Leland Woodall
Sent: 13 May 2008 14:47
To: [log in to unmask]
Subject: [TN] Stainless Steel Contamination Question
Importance: High
Hi Everyone,
We've had a problem lately with fine strands of stainless steel wire
being found on top of some of our .5 mm pitch ICs. This
has caused both internal and external issues, and we've yet to identify
the source.
It's definitely formed wire, with a thickness ranging from 7 to 10
microns, and up to 3 mm in length.
Our automated optical inspection stations can only reliably detect
widths of 12 to 15 microns.
I've checked the internet in an attempt to find common applications of
this wire. I've found two, and they were for ultra-fine
filters and stencil screen mesh. We've investigated (I think) all of
our machinery that would utilize filters this small and
have found no such usage.
I've also checked every stencil in our plant, and all of our mesh
material is some type of a plastic compound.
Do you have any idea where this stainless steel might be coming from?
Any suggestions would be sincerely appreciated!
Thanks,
Leland
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