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Forum: Reliability & Maintainability Questions and Answers

Topic: Reliability & Maintainability Questions and Answers

Topic Posted by: Reliability & Maintainability Forum ( )
Organization: System Reliability Center
Date Posted: Mon Aug 31 12:47:36 US/Eastern 1998

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Posted by: Floyd Kreuze ( )
Organization:Honeywell International
Date posted: Thu Jun 20 13:05:33 US/Eastern 2002
Subject: Bending of Ceramic Chip Capacitors
Quantitative information is needed on very small C values of ceramic chip capacitors in regard to the change in capacitance value as a function of bending of the capacitor body.


Subject: Bending of Ceramic Chip Capacitors
Reply Posted by: Adrian Piaschyk ( )
Organization: Reliability Analysis Center
Date Posted: Wed Jun 26 15:55:56 US/Eastern 2002
Quantitative information on the change in capacitance when a capacitor is being flexed is not a well research subject. The research on flexing or bending capacitors has been in the area of flex to fracture or a capacitors resistance to fracture. However, a sole article surfaced from the search on changing capacitance with flexing the housing. The article is included in the 44th Electronic Components & Technology Conference of 1994 (ISBN 0569-5503 or IEEE #94CH3241-7). The article title, “Capacitance Monitoring While Flex Testing,” was written by Jim Bergenthal & John D. Prymak of KEMET Electronics Corporation. In the article a ram fixture bent a FR-4 type board with various capacitors mounted in the center of the board. Quoting from the article, “At 5.6 seconds into the test, the deflection is ~2.1mm and the capacitance drops suddenly. Prior to this there is some wavering of the capacitance. In many cases, a steady decay in capacitance to –15% will precede the sudden drop. What is most interesting in this response is that, because the unit is monitored throughout the test, the capacitance eventually returns to 99 nFd as if there was no change at all.” From the above statement and testing it is safe to assume that flexing of a capacitor results in a drop in capacitance, the actually capacitance value drop was not determined. Other factors that could influence the change in capacitance under flexure would be the applied voltage, manufacturing process, and chip size.

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