[tinwhiskers] Re: New study on coating to mitigate whiskers
- From: "Fritz, Dennis D." <DENNIS.D.FRITZ@xxxxxxxx>
- To: <tinwhiskers@xxxxxxxxxxxxx>, <tinwhiskers@xxxxxxxxxxxxx>
- Date: Fri, 15 May 2009 14:40:46 -0400
What is your whiskers inspection methodology?
I am getting ready to do a study with Purdue undergraduate interns (who work
for a VERY attractive price for our program). We will determine both the
extent of whiskers growth on commercial boards - scrap cell phones and laptops,
and the ease of measurement by "semi-skilled" operators. We will be using
optical microscope, enhanced digital microscope, and simple SEM.
Can you share your proceedures?
Denny Fritz
SAIC - Merrillville, IN
________________________________
From: tinwhiskers-bounce@xxxxxxxxxxxxx on behalf of Jim Bunn
Sent: Fri 5/15/2009 10:55 AM
To: tinwhiskers@xxxxxxxxxxxxx
Subject: [tinwhiskers] Re: New study on coating to mitigate whiskers
I think they are saying it works if the thickness is at least 2mils. Or maybe
that the coating is better than nothing.
We have a lot of uncoated stuff out there running a test right now. And it's
pretty comprensive considering the voltage levels that we are using in the
PCUs. I'm suprised that we have not had some kind of problem.
________________________________
From: tinwhiskers-bounce@xxxxxxxxxxxxx on behalf of Pedro Tort
Sent: Thu 5/14/2009 7:48 AM
To: tinwhiskers@xxxxxxxxxxxxx
Subject: [tinwhiskers] New study on coating to mitigate whiskers
The National Physics Laboratory in UK has undertaken a study on the capability
of different coatings to mitigate tin whiskers growth. The results of this
investigation reinforces the findings of Jay Bruse and Dr. Henning Leidecker
who back in 2007 found the Uralane 5750 Polyurethane was an effective
mitigation strategy for tin whiskers provided the nominal coating thickness was
2mils.
I quote from the first issue of the NPL Electronics Interconnection Newsletter:
"The use of conformal coatings is seen as the only practical means of
controlling whisker growths shorting adjacent conductors on a PCB. NPL has
studied three types of coating, to assess their effectiveness for inhibiting
whisker growth.
Two coatings, polyurethane and paraxylene both were found to reduce the growth
of whiskers for up to 150 days of testing, compared with failure of 14 days for
uncoated samples. The acrylic coating was found not to perform as well as the
others in parallel tests. All coatings failed to provide sufficient protection
in areas of insufficient coating coverage, at corners and sides of the test
samples."
Pedro Tort
Quality Manager
DigiProces, S.A.
Solsones, 87 - P.I. Pla de la Bruguera
P.O. Box 127
E-08211 CASTELLAR DEL VALLES
TEL. +34 937 142 132
FAX. +34 937 142 072
www.digiproces.com
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