US Patent 7517787 C4 joint reliability

In one embodiment, the invention provides a method comprising fabricating a die bump on a die, the die bump being shaped and dimensioned to at least reduce the flow of solder material used, to attach the die bump to a package substrate, towards an under bump metallurgy (UBM) layer located below the die bump. Advantageously, the method may comprise performing a substrate reflow operation to attach the package substrate to the die bump, without performing a separate wafer reflow operation to reflow the die bump.