Preparation of ultra-low CTE epoxy composite using the new alkoxysilyl-functionalized bisphenol A epoxy resin

The high coefficient of thermal expansion (CTE) of the epoxy composite frequently causes the CTE-mismatch problem in semiconductor packaging. However, when the epoxy resins available currently are used for composite, the CTE-mismatch problem is inevitable even at the highly-filled conditions. In this study, the new type of bisphenol A (BPA) epoxy resin, i.e., ethoxysilyl-functionalized BPA epoxy was synthesized for the ultra-low CTE epoxy composite. The new epoxy composite with 85 wt% of silica content showed the ultra-low CTE of 3.2 ppm/°C and 6.0 ppm/°C at the temperature ranges of T < Tg and T > Tg, respectively. For comparison, the non-functionalized BPA epoxy composite was prepared under the similar conditions and it showed the CTE values of 8 ppm/°C and 40 ppm/°C at the temperature ranges of T < Tg and T > Tg, respectively. In order to understand the unique feature of the alkoxysilyl-functionalized epoxy, the reaction mechanism of the new epoxy was investigated using the model compound. [Display omitted] •New class of epoxy resin, i.e, alkoxysilyl-functionalized epoxy is synthesized.•The epoxy composite shows the ultra-low CTE of 4.6 ppm/°C, slightly higher than wafer.•The curing mechanism is studied in order to understand unique feature of new epoxy.