[tinwhiskers] Re: R: Re: New study on coating to mitigate whiskers
- From: Steve Smith <steve@xxxxxxxxxxxxxxxxxxxxxx>
- To: "White, Robert" <Robert.White@xxxxxxxxxxxxx>
- Date: Wed, 20 May 2009 12:14:49 -0700
What this appears to be saying is that within a year the Federal
Government is going to issue some sort of edict, and the States may
not issue their own. That's probably a good thing. Left to their own
devices, California would legislate science and Natural Law, as they
have in the past.
Those on this list in the U. S. A, please tell your elected
representatives that any forthcoming legislation in this area needs to
be in compliance with www.nepa.gov/nepa/regs/nepa/nepaeqia.htm which
basically requires an Environmental Impact Report (EIR) be prepared.
The change to pure-tin-finishes and the attendant risk of
tin-whisker-related failures, as well as this legislation itself, both
appear to require an EIR.
Steve Smith
WR> Wow! Thanks for posting this. RoHS USA makes it’s appearance.
WR> Wonder what means I can use to provide feedback on the exemptions
WR> listed in Section 4 (a). I guess we need to work through our local
WR> Representative of the House? Does anyone know if IPC or any other group is
mounting a response?
WR> Best Regards,
WR> Bob White
WR> Director of Safety and Environmental Compliance
WR> Power-One, Inc.
WR> Tel: +1 805 384-5391
WR> Fax: +1 805 987-3781
WR> robert.white@xxxxxxxxxxxxx<mailto:robert.white@xxxxxxxxxxxxx>
WR> ________________________________
WR> From: tinwhiskers-bounce@xxxxxxxxxxxxx
WR> [mailto:tinwhiskers-bounce@xxxxxxxxxxxxx] On Behalf Of Patrick Bruneel
WR> Sent: Wednesday, May 20, 2009 10:27 AM
WR> To: tinwhiskers@xxxxxxxxxxxxx
WR> Subject: [tinwhiskers] Re: R: Re: New study on coating to mitigate whiskers
WR> Hard to believe but check the link below
WR> http://www.govtrack.us/congress/billtext.xpd?bill=h111-2420
WR> Patrick
WR> ________________________________
WR> From: tinwhiskers-bounce@xxxxxxxxxxxxx
WR> [mailto:tinwhiskers-bounce@xxxxxxxxxxxxx] On Behalf Of Ron Southworth
WR> Sent: Monday, May 18, 2009 10:51 AM
WR> To: tinwhiskers@xxxxxxxxxxxxx
WR> Subject: [tinwhiskers] Re: R: Re: New study on coating to mitigate whiskers
WR> Thanks Judy
WR> Ron Southworth
WR> ________________________________
WR> From: tinwhiskers-bounce@xxxxxxxxxxxxx
WR> [mailto:tinwhiskers-bounce@xxxxxxxxxxxxx] On Behalf Of Little, Judy W
(EHCOE)
WR> Sent: Tuesday, 19 May 2009 1:35 AM
WR> To: tinwhiskers@xxxxxxxxxxxxx
WR> Subject: [tinwhiskers] Re: R: Re: New study on coating to mitigate whiskers
WR> Denny,
WR> Have you seen the wonderful video lessons in observing whiskers
WR> on the NASA Tin Whisker website? If not, just go to:
WR> http://nepp.nasa.gov/whisker/video/inspection/index.html
WR> Judy Little
WR> Honeywell, Clearwater, Florida
WR> ________________________________
WR> From: tinwhiskers-bounce@xxxxxxxxxxxxx
WR> [mailto:tinwhiskers-bounce@xxxxxxxxxxxxx] On Behalf Of Fritz, Dennis D.
WR> Sent: Sunday, May 17, 2009 20:16
WR> To: tinwhiskers@xxxxxxxxxxxxx
WR> Subject: RE: [tinwhiskers] R: Re: New study on coating to mitigate whiskers
WR> We will have that capability, in addition to several versions of
WR> ring lights, fiber-optic "goose neck" lights, etc. Seems to me
WR> that the "shine' or the reflection off the whisker is important. I have
the JEDEC spec.
WR> Denny
WR> ________________________________
WR> From: tinwhiskers-bounce@xxxxxxxxxxxxx on behalf of Gabriele Sala
WR> Sent: Sat 5/16/2009 5:45 AM
WR> To: tinwhiskers@xxxxxxxxxxxxx
WR> Subject: [tinwhiskers] R: Re: New study on coating to mitigate whiskers
WR> Hi Denny,
WR> Here (from JEDEC Std. 22-A121A ) you can find some help.
WR> In my experience Optical Stereo from 40X to 150X is good
WR> enough, it depends how deep you want to investigate.
WR> You must be careful when handling boards because whiskers are very fragile
WR> Just my 2 € ‘ cents
WR> Best Regards
WR> Gabriele Sala
WR> CT-91
WR> --------------------
WR> From the free download JEDEC Standards
WR> http://www.jedec.org/download/default.cfm
WR> Look for
WR> JEDEC Standard No. 22-A121A
WR> Test Method for Measuring Whisker Growth on Tin and Tin Alloy Surface
Finishes
WR> (Revision of JESD22-A121.01, December 2005)
WR> Last level JULY 2008
WR> Page 3
WR> 4.3 Optical stereomicroscope (Optional)
WR> Optical stereomicroscope with adequate lighting capable of 50X to 150X
magnification and capable
WR> of detecting whiskers with a minimum length of 10 microns, per Annex B. If
tin whiskers are
WR> measured with an optical system, then the system must have a
WR> stage that is able to move in three
WR> dimensions and rotate, such that whiskers can be positioned
WR> perpendicular to the viewing direction
WR> for measurement.
WR> 4.4 Optical microscope (Optional)
WR> Optical microscope with adequate lighting capable of 100X to 300X
magnification and capable of
WR> measuring whiskers with a minimum length of 10 microns, per Annex B. For
tin whisker
WR> measurements, the optical system must have a stage that is able to move in
three dimensions and
WR> rotate, such that whiskers can be positioned perpendicular to the viewing
direction for
WR> measurement.
WR> 4.5 Scanning electron microscope
WR> Scanning electron microscope (SEM) capable of at least 250X
WR> magnification. An SEM fitted with
WR> an X-ray detector is recommended for elemental identification.
WR> From:
WR> tinwhiskers-bounce@xxxxxxxxxxxxx<mailto:tinwhiskers-bounce@xxxxxxxxxxxxx>
WR>
[mailto:tinwhiskers-bounce@xxxxxxxxxxxxx<mailto:tinwhiskers-bounce@xxxxxxxxxxxxx?>]
On Behalf Of Fritz, Dennis D.
WR> Sent: Friday, May 15, 2009 11:41 AM
WR> To: tinwhiskers@xxxxxxxxxxxxx<mailto:tinwhiskers@xxxxxxxxxxxxx>;
WR> tinwhiskers@xxxxxxxxxxxxx<mailto:tinwhiskers@xxxxxxxxxxxxx>
WR> Subject: [tinwhiskers] Re: New study on coating to mitigate whiskers
WR> What is your whiskers inspection methodology?
WR> I am getting ready to do a study with Purdue undergraduate
WR> interns (who work for a VERY attractive price for our program).
WR> We will determine both the extent of whiskers growth on commercial
WR> boards - scrap cell phones and laptops, and the ease of
WR> measurement by "semi-skilled" operators. We will be using optical
WR> microscope, enhanced digital microscope, and simple SEM.
WR> Can you share your proceedures?
WR> Denny Fritz
WR> SAIC - Merrillville, IN
WR> ________________________________
WR> From:
WR> tinwhiskers-bounce@xxxxxxxxxxxxx<mailto:tinwhiskers-bounce@xxxxxxxxxxxxx>
on behal f of Jim Bunn
WR> Sent: Fri 5/15/2009 10:55 AM
WR> To: tinwhiskers@xxxxxxxxxxxxx<mailto:tinwhiskers@xxxxxxxxxxxxx>
WR> Subject: [tinwhiskers] Re: New study on coating to mitigate whiskers
WR> I think they are saying it works if the thickness is at least
WR> 2mils. Or maybe that the coating is better than nothing.
WR> We have a lot of uncoated stuff out there running a test right
WR> now. And it's pretty comprensive considering the voltage levels
WR> that we are using in the PCUs. I'm suprised that we have not had some kind
of problem.
WR> ________________________________
WR> From:
WR> tinwhiskers-bounce@xxxxxxxxxxxxx<mailto:tinwhiskers-bounce@xxxxxxxxxxxxx>
on behalf of Pedro Tort
WR> Sent: Thu 5/14/2009 7:48 AM
WR> To: tinwhiskers@xxxxxxxxxxxxx<mailto:tinwhiskers@xxxxxxxxxxxxx>
WR> Subject: [tinwhiskers] New study on coating to mitigate whiskers
WR> The National Physics Laboratory in UK has undertaken a study on
WR> the capability of different coatings to mitigate tin whiskers
WR> growth. The results of this investigation reinforces the findings
WR> of Jay Bruse and Dr. Henning Leidecker who back in 2007 found the
WR> Uralane 5750 Polyurethane was an effective mitigation strategy for
WR> tin whiskers provided the nominal coating thickness was 2mils.
WR> I quote from the first issue of the NPL Electronics Interconnection
Newsletter:
WR> "The use=2 0of conformal coatings is seen as the only practical
WR> means of controlling whisker growths shorting adjacent conductors
WR> on a PCB. NPL has studied three types of coating, to assess their
WR> effectiveness for inhibiting whisker growth.
WR> Two coatings, polyurethane and paraxylene both were found to
WR> reduce the growth of whiskers for up to 150 days of testing,
WR> compared with failure of 14 days for uncoated samples. The acrylic
WR> coating was found not to perform as well as the others in parallel
WR> tests. All coatings failed to provide sufficient protection in
WR> areas of insufficient coating coverage, at corners and sides of the test
samples."
WR> Pedro Tort
WR> Quality Manager
WR> DigiProces, S.A.
WR> Solsones, 87 - P.I. Pla de la Bruguera
WR> P.O. Box 127
WR> E-08211 CASTELLAR DEL VALLES
WR> TEL. +34 937 142 132
WR> FAX. +34 937 142 072
WR> www.digiproces.com<http://www.digiproces.com/>
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--
Best regards,
Steve mailto:steve@xxxxxxxxxxxxxxxxxxxxxx
www.consultingscientist.us
http://www.pickensplan.com/
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