PCB Bonding (Wire Bonding) in Chip Production

PCB bonding (wire bonding) is a chip production process that connects circuits using wires, typically gold or aluminum. This method is employed before encapsulation to link the internal circuitry of the chip with the package leads or the gold-plated copper foil on the PCB.

The process involves ultrasonic waves (usually 40–140 kHz) generated by an ultrasonic generator. These waves are converted into high-frequency vibrations by a transducer and transmitted to the bonding wedge through an amplitude transformer. When the bonding wedge contacts the wire and the component to be soldered, the combination of pressure and vibration causes the surfaces of the metals to rub against each other.

This friction breaks the oxide layer and causes plastic deformation, bringing two pure metal surfaces into close contact. At this point, the surfaces bond at an atomic level, creating a strong mechanical connection.

After bonding (i.e., connecting the circuit to the leads), the chip is typically encapsulated with black resin for protection.