Electrodeposited Copper-Graphite Composites for Low-CTE Integrated Thermal Structures

摘要

Emerging high-power and high-temperature electronic modules require thick copper structures for power-supply, thermal vias, heat-spreaders, and also as carriers or lead-frames for high-power packages. Such structures should coexist with glass and other low-CTE substrates to meet high-temperature performance, dimensional stability and superior device interconnection reliability with low stresses and warpage. The primary challenge with these packages arises from the coefficient of thermal expansion (CTE) mismatch between the conductors and the substrates. Cu-graphite composites with glass-matched CTE are explored to address this challenge through analytical modeling of properties such as CTE, Young's modulus and thermal conductivity, FEM predictions of glass warpage and stresses, process development to deposit copper-graphite composite films with high graphite loading of 64 vol. %, and warpage measurements using shadow-moire. Results indicate that Cu-graphite composites can mitigate the warpage and stress issues in high-temperature and high-power packages.