Metal Whiskers: Failure Modes & Mitigation Strategies - NEPP - NASA
Metal Whiskers: Failure Modes & Mitigation Strategies - NEPP - NASA
Metal Whiskers: Failure Modes & Mitigation Strategies - NEPP - NASA
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Crystal with Tin-Plated Kovar Leads<br />
(with Nickel Underplate)<br />
• Leads were Hot Solder Dipped (Sn63Pb37)<br />
within 50 mils of Glass Seal BEFORE Mounting<br />
to enhance solderability<br />
• Dip was not 100% of leads due to concerns of<br />
inducing harm to glass seal<br />
Hot Solder Dip<br />
Benefits & Limitations<br />
Field <strong>Failure</strong> ONE Year After Assembly<br />
December 5, 2007 <strong>Metal</strong> <strong>Whiskers</strong>:<br />
<strong>Failure</strong> <strong>Modes</strong> and <strong>Mitigation</strong> <strong>Strategies</strong><br />
Tin <strong>Whiskers</strong> (~60 mils) Grew on<br />
NON-Dipped Region Shorting to Case<br />
Causing Crystal to Malfunction<br />
• No <strong>Whiskers</strong> on Hot Solder Dipped Surface<br />
• ABUNDANT whiskers on the Non-Dipped Surface<br />
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