Fine Pitch Vertical Wire Bonding

Vertical wire bonding for fine pitch application is examined in memory sector focusing on the development of using half-cut capillary and 18μm bonding wire. Factors such as vertical wire post height and wire types are mainly investigated. A stable bonding process window with low variation in post height (ΔH) within 10μm is observed for 150 to 350μm post height. Wires with moderate ductility of 4N gold (Au), 2N Au and Coated silver (Ag) exhibited low variation in X-shift, Y-shift, and post height. All other examined wire types: Alloyed-Ag, soft 4N copper (Cu), 2N Cu, gold flash palladium (Pd) coated copper (AFPC) met the requirements for vertical wire bonding on optimizing the key factors, wire diameter, wire elongation, vertical wire post height, and capillary type.