A novel thermally conductive transparent die attach adhesive for high performance LEDs

•A die attach adhesive was designed with cross-linked epoxy-silicone and fused silica.•Both high thermal conductivity and low viscosity are achieved.•Similar refractive indexes of matrix and filler results in high transmittance.•Epoxy-silicone improves the adhesion to the bonding surfaces comparing with silicone.•The improved thermal, optical and reliability performance of LEDs are achieved.