The use of acoustic emission to determine the integrity of large hybrid packages

Abstract

The general objective of the program was to develop tests to determine the integrity of large hybrid packages under various thermal and mechanical stresses that may be encountered during assembly, during installation in systems, or in operation. Several measurement techniques are being investigated, but emphasis is placed on acoustic emission test procedures. The specific objectives studied during the initial period were: (1) determination of the effects of avionics environmental vibration on the seals of hybrid packages mounted on printed-circuit (PC) boards; (2) development of an acoustic emission detector sensitive to surface waves, but insensitive to vibration-induced cable noise; (3) development of a hightemperature (125°C) open-package helium leak test to observe marginal seal damage; (4) development of an acoustic emission test for inspection of hybrid packages during high-temperature thermal shock; and (5) determination of possible damage to seals during thermocompression and thermosonic bonding, during lead forming, and during other assembly operations.