Hi John, Yes high molecular weight compounds were impregnated or coated on
"pink" A/s bags which with moisture from air made a sufficiently conductive
surface. These compounds can transfer to anything in bag and [also as Brian
says moulding compounds] bringing with them the sort of problems you would
expect. This problem was recognised with respect to amines in particular
some years ago. Probably long enough ago for people to have forgotten about
it and therefore to buy on price without fear of consequences. As Joyce said
there is more than one pink.
Incidentally as long as there is a little humidity around a plain paper bag
is just as effective for ESP, bit of a tearing problem of course. But they
are really cheap.
HAPPY NEW YEAR
Regards
Mike Fenner
Indium Corporation
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-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of John Burke
Sent: Wednesday, January 07, 2009 12:22 AM
To: [log in to unmask]
Subject: Re: [TN] Potential contamination from pink colored antistatic foam
Hmmmmmmmmm,
Anti-static pink bags and foam for electronics use used to be manufactured
by coating (or actually blooming) the material with amines. The way that
they work is that the amines are hydrophilic and work by attracting
moisture.
Most anti static products these days are amine free - you might want to
check.
Most problems with this that I recall from about 15 - 20 years ago is that
if the board is placed in contact with one of these bags or foam before
conformal coating it can impact the cure schedule, presumably due to the
board coming into contact with a moisture loaded amine surface.
More than that I cannot recall but I am sure Mike Fenner will enlighten us
when Europe wakes up
John Burke
(408) 515 4992
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Joe Macko
Sent: Tuesday, January 06, 2009 2:58 PM
To: [log in to unmask]
Subject: [TN] Potential contamination from pink colored antistatic foam
Hi All.
My question is related to a comment one of our CMs recently made about
not allowing populated/soldered boards to come in direct contact with
pink colored antistatic foam for extended periods of time. This CM was
notified by another customer that they observed discoloration of solder
joints, solderability issues and /or conformal coat adhesion problems
after ~ 90 days due probably to either out gassing and/or a chemical
reaction with the ant-stat chemicals used in the foam. At one time I did
hear about N'octonic acid (not sure of spelling) in pink poly static
bags causing problems but have not heard anything recently.
Has anyone heard of or experienced such issues with the use of such
material as pink colored antistatic foam? Is there a safe anti-stat
foam that does not have these issues/concerns? Is there a mil spec or
some other industry type spec that regulates the type of anti-stat
material used with electronics? thanks
Best Regards,
-Joe
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