Development of high performance photo-curable nanocomposites for electronics packaging

A novel photo-curable nanocomposite material which can act both as a photoresist and a stress redistribution layer applied on the wafer level was synthesized and studied. In the experiments, the 20nm silica fillers are modified by silane coupling agent through the hydrolysis and condensation reaction and then incorporated into the epoxy matrix. A photo-sensitive initiator is added into the formulation which can release the cations after UV exposure and initiate the epoxy crosslinking reaction. The photo-crosslinking reaction of the epoxy makes it a negative tone photoresist. The curing reaction of the nanocomposites is monitored by the differential scanning calorimeter (DSC) with photo-calorimetric accessory (PCA). TEM picture shows the filler is well dispersed in the epoxy matrix; therefore the problems associated with filler agglomerations can be eliminated. The thermal mechanical properties of photo-cured nanocomposites thin film are measured. The addition of nano-size silica fillers not only reduces the thermal expansion and improves the mechanical property of the epoxy, but also has less influence on the optical property of the epoxy, which insures the occurrence of the photo reaction in epoxy