Metal Whiskers: Failure Modes & Mitigation Strategies - NEPP - NASA

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A Case for Whisker Mitigation Strategies? Tin Whiskers on Tin-Plated Axial Leaded Diodes • PWB and components were NOT Conformal Coated • Diode Leads were NOT Hot Solder Dipped December 5, 2007 Metal Whiskers: Failure Modes and Mitigation Strategies Images Courtesy of T. Riccio (STPNOC) 16
Three Whisker Mitigation Strategies Mitigation – to make less severe or painful Merriam-Webster Dictionary • Avoid Use of Whisker Prone Surface Finishes – Perform independent materials composition analysis – “Trust, But VERIFY!” using X-ray Fluorescence (XRF), Energy Dispersive X-ray Spectroscopy (EDS), et al • Conformal Coat – Can slow whisker growth – Can block whiskers from electrically shunting distant conductors • Remove/Replace Tin Finishes When Practical – Hot Solder Dip using lead-tin (Pb-Sn) solders – “First Do No Harm” Principle December 5, 2007 Metal Whiskers: Failure Modes and Mitigation Strategies Risk “Mitigation” ≠ Risk “Elimination” 17
Page 1 and 2: Metal Whiskers: Failure Modes and M
Page 3 and 4: What are Tin or Zinc or Cadmium Whi
Page 5 and 6: Whisker Resistant Metal Coatings
Page 7 and 8: 1960’s Vintage Transistor Guess W
Page 9 and 10: “There is a name for those who su
Page 11 and 12: Metal Whisker Melting Current -- Pt
Page 13 and 14: Sustained Metal Vapor Arcing • Ga
Page 15: My Whisker “Stress Relaxation The
Page 19 and 20: NASA Goddard Whisker Mitigation Stu
Page 21 and 22: Uralane 5750 - 2 Mils Thick 9-Years
Page 23 and 24: 2 Mils Uralane = Very Effective Whi
Page 25 and 26: Whiskers Lift and Peel Conformal Co
Page 27 and 28: Thank Goodness for Euler Buckling a
Page 29 and 30: Effects of Conformal Coating -- 2
Page 31 and 32: Contact Information Jay Brusse Pero
Page 33 and 34: Tin Whiskers Forming “Circus Tent
Page 35 and 36: A Few Recent Whisker Experiences
Page 37 and 38: • Basic Equipment: - Binocular Mi
Page 39 and 40: Field Technicians and Failure Analy
Page 41 and 42: "The Five Stages of Metal Whisker G
Page 43: An Example of “Melting” a Tin W

Metal Whiskers: Failure Modes & Mitigation Strategies - NEPP - NASA

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