Hi Denny, Here (from JEDEC Std. 22-A121A ) you can find some help. In my experience Optical Stereo from 40X to 150X is good enough, it depends how deep you want to investigate. You must be careful when handling boards because whiskers are very fragile Just my 2 € ‘ cents Best Regards Gabriele Sala CT-91 -------------------- From the free download JEDEC Standards http://www.jedec.org/download/default.cfm Look for JEDEC Standard No. 22-A121A Test Method for Measuring Whisker Growth on Tin and Tin Alloy Surface Finishes (Revision of JESD22-A121.01, December 2005) Last level JULY 2008 Page 3 4.3 Optical stereomicroscope (Optional) Optical stereomicroscope with adequate lighting capable of 50X to 150X magnification and capable of detecting whiskers with a minimum length of 10 microns, per Annex B. If tin whiskers are measured with an optical system, then the system must have a stage that is able to move in three dimensions and rotate, such that whiskers can be positioned perpendicular to the viewing direction for measurement. 4.4 Optical microscope (Optional) Optical microscope with adequate lighting capable of 100X to 300X magnification and capable of measuring whiskers with a minimum length of 10 microns, per Annex B. For tin whisker measurements, the optical system must have a stage that is able to move in three dimensions and rotate, such that whiskers can be positioned perpendicular to the viewing direction for measurement. 4.5 Scanning electron microscope Scanning electron microscope (SEM) capable of at least 250X magnification. An SEM fitted with an X-ray detector is recommended for elemental identification. From: <mailto:tinwhiskers-bounce@xxxxxxxxxxxxx> tinwhiskers-bounce@xxxxxxxxxxxxx [ <mailto:tinwhiskers-bounce@xxxxxxxxxxxxx?> mailto:tinwhiskers-bounce@xxxxxxxxxxxxx] On Behalf Of Fritz, Dennis D. Sent: Friday, May 15, 2009 11:41 AM To: <mailto:tinwhiskers@xxxxxxxxxxxxx> tinwhiskers@xxxxxxxxxxxxx; <mailto:tinwhiskers@xxxxxxxxxxxxx> tinwhiskers@xxxxxxxxxxxxx Subject: [tinwhiskers] Re: New study on coating to mitigate whiskers 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: <mailto:tinwhiskers-bounce@xxxxxxxxxxxxx> tinwhiskers-bounce@xxxxxxxxxxxxx on behal f of Jim Bunn Sent: Fri 5/15/2009 10:55 AM To: <mailto:tinwhiskers@xxxxxxxxxxxxx> 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: <mailto:tinwhiskers-bounce@xxxxxxxxxxxxx> tinwhiskers-bounce@xxxxxxxxxxxxx on behalf of Pedro Tort Sent: Thu 5/14/2009 7:48 AM To: <mailto:tinwhiskers@xxxxxxxxxxxxx> 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=2 0of 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 <http://www.digiproces.com> www.digiproces.com This email and any files contained therein is confidential and may contain privileged information. If you are not the named addressee(s) or you have otherwise received this in error, you should not distribute or copy this e-mail or use any of its content for any purpose. 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