Abstract: According to the thermal conductivity theory and Haiying Li’s researching data, a prediction formula, which can be used to predicate the thermal conductivity of carbon fiber, silica and epoxy mixed packaging composite, is obtained. Finite element analysis is used to compare temperature differences between low and high thermal conductivity of composites. And research shows that high thermal conductivity composite can decrease the temperature difference of underfill between chip and substrate, so that it can improve the temperature distribution of the flip chip, decrease the thermal stress of underfill and increase packaging reliability.

Key words: thermal conductivity, micro-electronic packaging, composite epoxy, underfill, flip chip