Perhaps an EMC gasket. One of the knitted mesh materials commonly used consists of knitted stainless steel fabric. There may
well be residues of silicones and other lubricates used in the knitting or weaving.


Best Regards
 
David Greig

-----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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