Wire Bonding Techniques in Semiconductor Packaging

Wire bonding is a crucial process in semiconductor packaging. The process uses tiny wires, um in diameter wires to connect the semiconductor chip to the substrate. Even though newer technologies WLCSP devices with direct flip chip capabilities, wire bonded devices are used for the majority of applications. 

Three main types of wire bonding processes are typically used.

Thermosonic bonding: 

Technique heat, force, and ultrasonic energy are applied to the wire to make a bond connection between the wire and the chip or substrate. Few decades back thermosonic bonding was limited to Au (Gold) wires but due to increasing Au prices, for industrial high volume application, Cu wires are now being used. 

Thermosonic bonding

Ultrasonic Bonding: 

Mainly used for Al (aluminum) wire boning, ultrasonic bonding uses only ultrasonic energy for bonding purposes. Since no heat is used, Ultrasonic bonding is usually done without the use of a heating element (for Au and Cu wire bonding the substrate is heated 150C and above). Process relays on pressure and vibration to achieve a cold weld between the surfaces. 

Ultrasonic Bonding

Thermocompression Bonding: 

This technique relies on heat and force but does not use ultrasonic energy. Using a bonding tool heat and force is applied to the wire making it deform and connect with the bonding surface. Often used with Au wire bonding due to its malleability, Thermocompression bonding with Au wires are used when ultrasonic energy might damage the device. 

Thermocompression Bonding

Each method of wire bonding offers its own unique advantages and chooses based on the specific needs of the semiconductor device application. This may be the choice of wire material, desired strength, or reliability.  Intech Technologies is here to discuss your specific requirement and offer our expertise on the desired application. Please feel free to contact us and discuss any of your packaging needs.