A study of impact performance of conductive adhesives

Electrically conductive adhesive is an environment- and user-friendly alternative to traditional lead-bearing solders in electronics packaging. However, current commercial conductive adhesives are not suitable in electronics packages, such as surface mount applications, due to some critical reliability issues. One of the critical issues is that current conductive adhesives do not have desirable impact strength. In the study described here, finite element analysis (FEA) was used to conduct the modal analysis of the packages and to estimate their natural vibration frequencies. Then, a series of conductive adhesives were formulated, and the dynamic properties and impact performance of these materials were studied. The experimental results were correlated to the results of the modal analysis. Constrained-layer damping theory was used to explain the results of the drop tests. It was found that (1) finite element modal analysis accurately predicts the vibration frequencies experienced by the components and (2) conductive adhesive materials with high damping properties in the vibration frequency range estimated by FEA show high impact performance.