Green Electronics Manufacturing

250 Green Electronics Manufacturing

the board, substrate, or lead frame, and makes a “stitch” bond to that pad,

nishing by breaking off the bond wire to begin another cycle. The gold stud

bump is summarized as follows:

• For gold stud bumping, the rst ball bond is made as described, but

the wire is then broken close above the ball. The resulting gold ball,

or “stud bump,” remaining on the bond pad provides a permanent,

reliable connection through the aluminum oxide to the underlying

metal.

• After the stud bumps are placed on a chip, they may be attened

(or “coined”) by mechanical pressure to provide a atter top sur-

face and more uniform bump heights, while pressing any remaining

wire tail into the ball. Each bump may be coined by a too ...