Modeling Kirkendall Vacancy Flux in Ternary SAC Solder Interfaces
Modelling vacancy transport in ternary SAC interfaces enables precise prediction of Kirkendall microvoid growth, preventing latent failure in high-reliability packaging.
High-Speed Shear Testing
Meaning
Destructive analytical methods used to evaluate the brittleness and strength of solder balls on semiconductor packages provide critical data on the reliability of electronic joints. Mechanical connections are subjected to high-speed shear testing to simulate the forces encountered during accidental drops or rough handling of a device. This process measures the force required to break the solder ball off its pad at various impact velocities.
It is used to identify the transition from a ductile fracture in the bulk solder to a brittle fracture at the intermetallic interface.
Kinetic Application
A specialized test head moves at speeds reaching several meters per second to strike the side of the solder sphere. This application of high-speed shear testing allows engineers to plot a curve showing how the joint strength decreases as the impact speed increases.
Fracture Characterization
After the test is completed, the surface of the break is examined to determine the failure mode. If the break occurs entirely within the solder, the joint is considered robust under impact.
Quality Benchmark
Production facilities use the energy absorption values from these tests to qualify new alloy compositions and surface finishes. Comparing the results against historical data helps in predicting the field performance of a new product design. The test provides a quantitative measure of the bond integrity that static tests cannot capture.
Detailed reports from the lab include the maximum force and the total energy dissipated during the impact.