Material characterization of corner and edgebond epoxy adhesives for the improvement of board-level solder joint reliability

In this paper, the material characteristics of six epoxies used for corner/edge-bonding are analyzed and compared to board-level mechanical reliability test. An innovative material characterization approach, button shear testing, provided an expedient method of determining adhesive strength between the epoxies and each relevant surface material. The board-level test included mechanical shock test. A number of SMT test devices are evaluated, including 1849 CBGA packages, and 190 ball count mezzanine connectors. The failure modes and fracture strengths of the material characterization tests and board-level tests are cross-referenced for comparison, and assessed for correlation. The results from the present study not only contribute to the characterization and selection methods of corner/edge-bonding epoxies, but also improve understanding of the corresponding relationship between material characterization testing and the more complex and costly board-level reliability tests.