During the temperature cycling test, the electrical resistance monitoring in each electrical circuit was performed using four interlinked Anatech STD-256 event detectors. The measured resistance is compared to a reference threshold that, if exceeded, generates a potential failure result. The detector network is controlled using a personal computer (PC) running the Anatech Windatalog (Version 2.0.0) software. Each detector allows 256 individual channels to be monitored, thus giving a maximum total of 1,024 channels for the interlinked network. Connection to the test boards is made using ribbon cables comprising of 37 individual wires (32 for monitoring channels and five for common-ground). Eight ribbon cables can be attached via the front panel of each STD-256.

The Windatalog package allows the user to determine the frequency at which measurements are taken. This is done by selecting a cycle time and the frequency of resistance measurements (polls) taken per cycle for each channel. Typically, the cycle time of event detection is chosen to match the thermal cycle time. When measurement is triggered, the detectors measure the resistance of each channel in turn. When a potential failure result is generated for a given channel, the software records the time of potential failure in terms of the number of cycles and polls. The default setting for the software is to record the time of each potential failure for a particular channel till a maximum preset number of potential failures are reached (typically 15). After this maximum is reached, the software continues to monitor...