High accuracy face down bonding with micro-ball alignment

Light edge emitting diode arrays are expected to be applied in optical writing units and optical transmission units. For a 63.5 /spl mu/m-pitch electrode connection, we succeeded in forming solder bumps on semiconductor electrodes by aligning solder balls, and bonding this device by making reflow connections with a face-down bonding method. Using a micro-ball 25 /spl mu/m in diameter, the connection was accurate to within /spl plusmn/2 /spl mu/m. It was verified that the initial characteristics of the face-down bonded device are essentially the same as those of a face-up mounted device fabricated by wire bonding.