What is wire bonding?
Wire bonding is the method of making interconnections between an integrated circuit (IC) or other semiconductor device and its packaging during semiconductor device fabrication. Although less common, wire bonding can be used to connect an IC to other electronics or to connect from one printed circuit board (PCB) to another. Wire bonding is generally considered the most cost-effective and flexible interconnect technology, and is used to assemble the vast majority of semiconductor packages. If properly designed, wire bonding can be used at frequencies above 100 GHz.
What are the Advantages of wire bonding?
Flexibility in terms of chip, housing and substrate geometry
The connection and its dependability are easy to test
Connection repair option
Option of different pad metallizations on the chip substrate
Reduction in manufacturing costs
Simple handling of complex circuits
Today’s Use of wire bonding
Today, using advanced equipment and technology, wire bonding can be completed on a much wider variety of different components and substrates. Different options in bondwires including gold, silver, copper and aluminum allow for various heat levels combined with pressure and ultrasonic vibrations.
The technicians setting up the process still have the challenge of selecting the right configurations based on the substrate, the chip component and the bondwire. Copper is often used in semiconductors as the bondwire because it can be effective as a very fine bondwire and also has an overall lower cost of production than other bondwire options.
While copper bondwire is the lower cost option, there are still many components that require the use of gold bondwire. This is a wire that has a 99.99% purity. There are also gold alloy wires that boost the bondwire strength and increase the durability and longevity of the component.
What are the challenges of using wire bonding?
In addition to the specific bondwire used for wire bonding of a microelectronic component or the semiconductor, there are other challenges that have to be carefully considered.
The correct bonding tool, which is used in ball bonding, has to be selected to have the right design and tip shape to suit the specific bonding requirement. A fine-pitch ball bonding process is very flat to the surface, which is often essential in microelectronic components and semiconductors where even a slightly raised surface can be a very serious issue.
Other issues to consider include the length of the bondwire that is affected during the heating process and if the application of the heat changes the wire and creates weak spots or area. This turn can impact the loop height of the wire, which needs to be carefully matched to the component specifications.