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 Chicago
Power Outage During a particular week in July 1995, over
240,000 Chicago-area customers had service interruptions and
over 1,300 failures to Commonwealth Edison’s (ComEd)
distribution equipment occurred. The Illinois Commerce Commission
retained Exponent’s engineering team to evaluate ComEd’s
performance during the crisis. Our findings showed that although
ComEd’s response was appropriate, a portion of the aging
distribution equipment had insufficient capacity for unusual
demands and high ambient temperatures. Recommendations were
made regarding the prevention and mitigation of future outage
situations.
 Semiconductor
and Electronics A PCI board experienced a burn-type failure.
Exponent’s investigation found that the failure was
caused by the pattern of the epoxy that was applied as the
integrated circuits were soldered to the board.
During the assembly process, the epoxy experienced a rapid
change in temperature and cracked, exposing the power and
ground traces, resulting in contamination, which provided
a resistive path between power and ground, leading to a burn.
We recommended a change in the assembly process and in the
board layout to correct this problem. Test structures were
also designed and implemented on future printed circuit boards
to correlate the performance of a board with its manufacturing
process.
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