Environmental Test
High-temperature acoustic microscopy allows the real-time observation of package-level defects as they expand or contract during simulated reflow profiles. Thermal stage acoustic testing combines a heated mounting fixture with a scanning transducer to evaluate component integrity under thermal stress. This method is highly effective for identifying defects that appear only when the package reaches operating temperature.
Thermal Deformation
Materials with differing coefficients of thermal expansion generate significant mechanical stresses as the stage temperature increases. If the internal interfaces are weak, these stresses force them to separate and form gaps. The acoustic scan captures these changes in real time, showing the development of delaminations as they occur rather than after the sample cools.
Failure Mechanism
Tracking these thermal transitions reveals the precise temperatures where package structures fail or separate. Some delaminations are fully reversible, closing back up when the package returns to room temperature and becoming invisible to post-test scans. Using this testing method helps engineers identify materials and designs that are susceptible to these dynamic defects before starting high-volume production runs.
This capability is invaluable when qualifying new lead-free molding compounds that must endure high peak temperatures without losing adhesion to the underlying copper leadframe during the solder reflow cycle.
