DESIGNING MULTIFUNCTIONAL INTERFACES TO BRIDGE HETEROGENEOUS MATERIALS TO REDUCE THERMAL FATIGUE

Composite interfaces between heterogeneous materials exist in many applications which includes electronics packaging. The interface will affect properties such as mechanical integrity during thermal cycling, heat transport and electrical transport due to the inherent disparate properties such as coefficient of thermal expansion (CTE), atomic structure, interface bonding and fabrication processes. Novel interface engineering will be vital for electronics packaging utilized in extreme environment temperatures beyond the standard ranges such as -55 °C to 150 °C. The failure of standard electronics packaging materials with heterogeneous interfaces under thermal cycle fatigue is investigated. Based on the failure analysis, several multifunctional interfaces are developed to bridge the heterogeneous interface and to provide the desired properties and functionality. Approaches to achieve these heterogeneous structures, the materials choices to preserve the multifunctional properties and the modeling predictions are considered. Test structures are prepared of the candidate interfaces, the morphologies are investigated and testing of the thermal cycle fatigue properties over the range -55 °C to 300 °C is performed and will be discussed.