Bonding tools

SPT’s product offerings have expanded significantly over the years, but the Petaluma division’s core business is still CIM bonding tools for integrated circuits (I/Cs). The bonding tool capillaries it molds from the ultrapure, high-density ceramic feedstocks that it compounds in-house are used to connect the internal circuitry of I/Cs to the lead frame.

Fine gold wire (18 to 33 µm in diameter) is fed though the capillary and is bonded into place at speeds of 16 wires/sec. The molded capillaries typically are .0625 inch (1.587 mm) in diameter and .437 inch (11.10 mm) long. They have a larger hole at the top and taper down to chamfered hole diameters typically ranging from 20 to 50 µm. SPT was certainly a pioneer in the field of micromolding as well.

Here’s how the process works: (1) A free-air ball of gold wire formed by electronic firing is centered inside the capillary chamfer; (2) the ball is bonded to the bond pad using ultrasonic energy, force, and temperature; (3) after the ball is bonded, the capillary rises, feeding wire through itself to the second bond position; (4) the stitch is then formed to the second bond position in a similar fashion to step two; (5) the tail is detached; and (6) a free air ball is formed for the next cycle.