35th International Symposium for Testing and Failure Analysis(ISTFA 2009), San Jose, CA, pp. 293-300, November 15-19, 2009

Degradation Analysis of Thick Film Chip Resistors

Bhanu Sood,
Diganta Das,
Michael H. Azarian
Michael Pecht

Center for Advanced Life Cycle Engineering (CALCE)
Department of Mechanical Engineering
University of Maryland
College Park, MD 20742, USA


Negative resistance drift in thick film chip resistors in high temperature and high humidity application conditions was investigated. This paper reports on the investigation of possible causes including formation of current leakage paths on the printed circuit board, delamination between the resistor protective coating and laser trim, and the possibility of silver migration or copper dendrite formation. Analysis was performed on a set of circuit boards exhibiting failures due to this phenomenon. Electrical tests after mechanical and chemical modifications showed that the drift was most likely caused by moisture ingress that created a conductive path across the laser trim.

Complete article is available to CALCE Consortium Members.


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