Investigating Stress in Hybrid Electronic Packages Using White Light Surface Profilometry

Abstract

Hybrid electronic packages are often used in space applications because of their rigidity, hermeticity, and good thermal dissipation properties. These properties make them highly reliable in the harsh space environment. However, a recent space application of hybrid electronic packages failed during testing. The failure was traced to cracks in the high temperature co-fired alumina ceramic substrates that resulted in the loss of electrical continuity in some packages. To investigate stress states and crack growth in the packages, a novel technique for stress determination using optical surface profilometry was developed. The technique employs a scanning white light surface profilometer to obtain topographical contour maps of the hybrid electronic packages. Surface curvature reveals the stress state of a component, which can affect its functionality and reliability. By comparing the topography during thermal cycling and de-processing of a fully assembled package, hypotheses regarding the build-up of stress can be investigated.