Assessing of Wire Bonding on Gold Plated Pads on Epoxy Mold Compound Wafer

Abstract

Epoxy mold is one of the materials being used in Fan-out Wafer Level Packaging (FOWLP). It is challenging to wire bond on epoxy mold compound wafer which the mold materials property is less stiff at high temperature if compare to silicon wafer. In this study, it has been using the reference bonding parameters from blanket Aluminium silicon chip to bond on gold pad on epoxy mold compound wafer. The reference bonding parameters could not be repeated on the epoxy mold compound wafer especially for copper wire. Nonstick on pad were seen. The bonding parameters required to stick the copper wire on the bond pad is far away different from the reference parameter. The wire pull readings were collected from the epoxy mold compound wafer after the wires were successfully bonded continuously. Wire pull readings of average 5.427gf was achieved for Au wire and average of 5.99gf for palladium-coated copper core wire. After 150DegC baking for 96hours, the wire pull average is 5.24gf and ball shear average is 21.65gf. Average wire pull of 6.32g and average ball shear of 29.69gf was achieved after 175DegC baking for 96 hours. In generally, all wire pulls >3gf.