A paper describes advanced ceramic column grid array (CCGA) packaging interconnects technology test objects that were subjected to extreme temperature thermal cycles. CCGA interconnect electronic package printed wiring boards (PWBs) of polyimide were assembled, inspected nondestructively, and, subsequently, subjected to extreme-temperature thermal cycling to assess reliability for future deep-space, short- and long-term, extreme-temperature missions.

The test hardware consisted of two CCGA717 packages with each package divided into four daisy-chained sections, for a total of eight daisy chains to be monitored. The package is 33×33 mm with a 27×27 array of 80%/20% Pb/Sn columns on a 1.27-mm pitch.

The change in resistance of the daisy-chained CCGA interconnects was measured as a function of the increasing number of thermal cycles. Several catastrophic failures were observed after 137 extreme-temperature thermal cycles, as per electrical resistance measurements, and then the tests were continued through 1,058 thermal cycles to corroborate and understand the test results. X-ray and optical inspection have been made after thermal cycling. Optical inspections were also conducted on the CCGA vs. thermal cycles. The optical inspections were conclusive; the x-ray images were not.

Process qualification and assembly is required to optimize the CCGA assembly, which is very clear from the x-rays. Six daisy chains were open out of seven daisy chains, as per experimental test data reported. The daisy chains are open during the cold cycle, and then recover during the hot cycle, though some of them also opened during the hot thermal cycle.

This work was done by Rajeshuni Ramesham of Caltech for NASA’s Jet Propulsion Laboratory. NPO-47341

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Reliability of Ceramic Column Grid Array Interconnect Packages Under Extreme Temperatures

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This article first appeared in the May, 2011 issue of NASA Tech Briefs Magazine.

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