On-board fault detector for monitoring component attachment

A simple, inexpensive, on-board fault detection approach for monitoring component attachment integrity during environmental testing is presented. It provides a practical, alternative aid in evaluating the impact of design and process variables on reliability. This high speed logic fault detector monitors daisy chain continuity of physically adjacent test ICs. Each test IC or IC sub-segment is provided with a dedicated "staring" monitor circuit with single-event, sub-microsecond response capability. Responses are latched pending operator Reset, providing an opportunity to record the sequence of occurance. Only four wires are required to connect the Unit Under Test board with a simple, two-button Controller. As described, the On-Board Fault Detector trades low cost and convenience for automated event logging. Advantages include low cost, relative immunity to false events, support of long-duration tests without dedicating expensive test equipment, and response to rare, short-duration events potentially missed by commutating testers. The paper illustrates how this approach was used to support qualification of large PBGAs for space applications..