Electronic circuits are often packaged in hermetically sealed metal cans with welded or soldered lids. Due to the susceptibility of the circuits and the wire interconnects to moisture and water vapor, the packages must be leak-free to a predetermined leak rate. High reliability circuits are leak tested to mil spec 883-c. These methods employ helium and krypton-85 as tracer gases and require extensive bombing. A proposed method a leak testing employing laser speckle correlation could replace or be a compliment to present methods. This new technique is fast, all-electronic and will test assembled circuit boards. The technique provides complete traceaility between the test parts and the test data. Laser speckle correlation promises considerable cost savings and increases in reliability and throughput at many points throughout the production of microcircuits.
