Electrical and Thermomechanical Modeling of Electrically Conductive Adhesives

Summary form only given. This research starts with the investigation of the contact resistance between filler particles in conductive adhesives. The contact resistance is measured between silver with different coating materials, and the relationship of tunnel resistivity-contact pressure is obtained based on the experimental results. 3-D microstructure models and resistor networks are built to simulate the electrical conduction in conductive adhesives. The total resistance of the resistor network is calculated based on the measured tunnel resistivity, measured epoxy shrinkage, and contact pressure calculated from finite element analysis. The effects of geometric properties of filler particles, such as size, shape and distribution, on the conductive property are studied by method of factorial design. Lap shear tests are performed on conductive adhesives under harsh conditions, including thermal cycling, high temperature and humidity aging, corrosion, vibration and impact. Mechanical stress/strain and electrical conduction of conductive adhesives are monitored during these tests. Microscopy is used to study the failure mechanism. The relationship between mechanical failure and electrical failure is investigated. Mechanical and electrical reliability of both the bulk conductive adhesive and interface between conductive adhesive and components are studied. Life prediction models of conductive adhesives will be built based on the experimental measurements