High-Speed Solder Ball Shear and Pull Tests vs. Board Level Mechanical Drop Tests: Correlation of Failure Mode and Loading Speed

This study compares high-speed bondtesting (shear and pull) with board level drop testing (BLDT) of BGA packages using Sn4.0%Ag0.5%Cu solder balls and either an ENIG or OSP package substrate surface finish. High-speed shear and pull testing were carried out at various speeds; failure modes were recorded, together with force and fracture energy data. In addition, detailed microscopic analysis (SEM and EDX) was executed on both complementary surfaces (ball and pad) of brittle fracture failures from both shear and pull test samples. The results of these studies showed close similarity to those from brittle fractures generated during BLDT of the same packages. Furthermore, there was strong correlation between various bondtesting parameters at which brittle fractures occurred and the number of drops to failure seen in BLDT. In summary, it is suggested that brittle fractures obtained in high-speed bondtesting are a strong indicator of BLDT behavior.