Loop Height Measurement for Wire Bonding

1. Application

As electronic equipment becomes thinner, the density of wires used to bond an integrated circuit (IC) chip to a lead frame or package board is increasing. Today, a technique called wire bonding is also used to connect multiple chips that are stacked in one package. Controlling the height and shape of the wire loops that are created in wire bonding is important to help ensure that IC chips fit inside packages as small as a few millimeters thick.

2. The Olympus solution

Olympus' STM7 measuring microscope is a proven solution for manual step measurement applications. With this microscope, the height of a wire loop can be quickly and accurately measured to help validate whether the wire bonding machine has been configured correctly. The STM7 microscope’s laser auto focus has a very small spot diameter of 1.0 μm, enabling users to focus on the bonding wire. The tracking auto focus enables inspectors to measure the highest point of a loop while precisely moving the XY stage (Figure 1).

Figure 1. The STM7 microscope makes it simple to measure the highest point of a wire loop.