An improvement of thermal conductivity of underfill materials for flip-chip packages

Effective heat dissipation is crucial to enhance the performance and reliability of electronic devices. In this work, the performance of encapsulants filled with carbon fiber was studied and compared with silica filled encapsulants. Encapsulants filled with mixed combination of fillers for optimizing key properties were also investigated. The thermal and electrical conductivities were investigated and glass transition temperature (Tg), thermal expansion coefficient (TCE), and storage modulus (E´) of these materials were studied with thermal analysis methods. The composites filled with both carbon fiber and silica showed an increase of thermal conductivity three to five times of that of silica filled encapsulants of the same filler loading while maintaining/enhancing major mechanical and thermal properties.