Abstract
A study of TAB outerbonding for resin-coated copper substrates revealed that 0.45μm is the minimum thickness of gold plating over conductors for stable and high reliable connections. Finger bonding deforms substrate surface resin and places a tensile force on the conductors. Minimizing the resulting cracks and tears means restricting bonding pressures to 6 to 7 kg/mm2 and tool temperature to 430 to 450°C. Fingers were Sn-Pb eutectically solder plated. After bonding, tin was hardly observed at the connections, suggesting that other elements remain at connections, and that the fingers are connected to conductors by Au-Sn alloying.
