Avian Ho, ASM Pacific Technology

Avian Ho, ASM Pacific Technology

In 2012 and beyond, most believe that the proliferation momentum towards Cu will accelerate even more strongly. Lead frame is getting wider, up to 100 mm. In future, even larger panel base leadframe may evolve.

With Au wire bonding as the interconnect and large lead frame or substrate sitting too long on the heater block on the wire bonder, there will be too much intermetallic growth. And device resistivity will shoot up many folds or even kill the device.

With the characteristically slow IMC growth using Cu wire, it has become a prominent and disruptive solution to Au wire bonding, with the emergence of high density solutions.

The whole ecosystem from wafer fab, probe, wire, capillary, wire bonding equipment, molding to packaging materials are trying to adapt to this new evolution.

The complexity in the process and material interaction to qualify Cu wire bonded packages is no longer an insurmountable challenge. Today, more packages are qualified with Cu wire than ever before. Cu wire bonding is already in mass production in many assembly packaging houses, exhibiting the level of maturity Cu wire bonding process is attaining.

Generally, Cu wire bonding productivity and mean time between assistance (MTBA) — is lower, in comparison with Au wire bonding. However, the technology envelop has been challenged by engineers. It is now possible to even produce Cu bonded parts faster than using Au wire.

As a key industry contributor, ASM confidently predicts High density lead frame solutions combined with Cu wire bonding will be the major activity in many of assembly packaging houses. This is because this combination of Cu interconnect with high density solution will give the best cost and electrical performance factors in our ever innovative semiconductor industry.