Minimizing the Bondline Thermal Resistance in Thermal Interface Materials Without Affecting Reliability

As electronic assemblies become more compact, with increased processing bandwidth and higher energy fluxes, thermal management is limiting several critical applications. The major technology limitation is the nonmetallic joining of devices to heat sinks using existing commercial thermal interface materials (TIMs). The present study starts a systematic study of the coupled interactions between materials formulation, manufacturing process, and thermal performance. Thermal bondlines were fabricated under controlled conditions with commercially available TIMs and a nanoparticle-modified epoxy. Force measurements during bondline fabrication provided information about the flow process. Thermal performance of the bondlines was evaluated with laser flash thermal diffusivity measurements. Relationships between flow parameters, final bondline microstructure, and bondline thermal resistance are discussed from the standpoint of reliability and performance.