Wire Bonding: Modern Applications, Technology Trends and Cost Considerations

Introduction

Wire bonding has long been the dominant method for connecting semiconductor dies to package lead frames and circuit boards, particularly in Chip-on-Board (COB) technology, where the die is directly mounted onto the PCB. Wire bonding for COB became popular in consumer electronics, such as calculators and early digital devices due to its reliability and cost efficiency in mass production.

Over time, wire bonding COB evolved to meet the demands of miniaturization and higher performance, becoming a critical technology in applications such as power LEDs, image sensors, power electronics, and high-performance computing. Today, wire bonding accounts for 75-80% of first-level interconnections in the microelectronics industry, providing reliable connections in compact, high-performance designs.

Modern Applications of Wire Bonding in Electronics

Wire bonding is used across a wide range of modern applications, offering flexibility, reliability, and cost-efficiency. Some of the key areas include:

• 3D Integrated Circuits (ICs): In 3D ICs, where multiple semiconductor dies are stacked vertically, wire bonding is vital for connecting these layers. As devices become more compact, the demand for high-density processing power has grown, making wire bonding indispensable in managing fine pitch and high pin counts. This technology is critical for high-performance computing, advanced mobile devices, and high-density digital electronics.

3D stacked die with wire bonds

• Power Electronics and Wide-Bandgap Semiconductors: Wire bonding is essential for packaging wide-bandgap semiconductors such as silicon carbide (SiC) and gallium nitride (GaN), which are used in high-power applications like electric vehicles and renewable energy systems. These semiconductors operate at high voltages and temperatures, and heavy-gauge copper wire bonding is often used to handle the higher current loads and ensure efficient power management.

Wire bonded power module (image source: Electronics Weekly, “Powering UP”, April 2022

• Optoelectronics and Image Sensors: As the resolution of image sensors increases, the number of connections required rises dramatically, making fine wire bonding essential. These high-performance, high-density designs are crucial for advanced consumer electronics, medical diagnostics, and security systems.

CMOS image sensor COB with wire bonds [image source: University of Alberta published in Sensors 2011]

• Chip-on-Board (COB) LEDs: COB technology is widely used in LED designs, providing higher lumen density and improved thermal management. Wire bonding enables compact LED arrays with efficient heat dissipation, leading to brighter, longer-lasting lighting solutions in automotive, industrial, and consumer applications.

COB LED array (image source: CREE)

Cost Considerations in Wire Bonding

While wire bonding offers significant advantages in terms of performance and space efficiency, cost remains an important factor, especially for large-scale production. The cost of wire bonding is influenced by several variables, including the type of material used, the complexity of the application, and the production volume.

• Material Costs: The cost of wire bonding materials varies widely. Gold wire bonding is the most expensive option, with a price around $349 per gram for 0.8 mil wire. However, copper and aluminum offer much more cost-effective alternatives, especially in applications where high conductivity and durability are still essential. For example, the same diameter of aluminum or copper bonding wire can be a fraction of the cost compared to gold, making them ideal choices for high-volume production.
• Manufacturing Costs: Wire bonding machines vary in cost depending on their level of automation. Manual or semi-automated machines can cost tens of thousands of dollars and are suitable for smaller-scale or prototype production, whereas fully automated machines can cost hundreds of thousands of dollars and are essential for large-scale production. For low-volume or non-recurring production runs, it is often more cost-effective to outsource the wire bonding process to an external manufacturer. These service providers can offer more affordable solutions without the need for companies to invest in expensive wire bonding equipment.
• Production Volume and Tooling Costs: Wire bonding becomes more cost-efficient with larger production volumes. Although the initial tooling costs for wire bonding setups are fixed, the cost per unit decreases as production scales. In high-volume production—such as hundreds of thousands to millions of units per year—COB designs can be more cost-effective than using standard packaged chips. This is because COB eliminates the need for die packaging, reducing assembly costs and allowing for more compact designs with fewer components.
• Example Cost Breakdown: For a basic COB design with 1770 um x 1258 um die and 21 wire bonds, costs can vary significantly depending on the level of automation and production volume. Here’s an example breakdown for a small batch of 100 units:
  • Wire bonding service and tooling charge: $500 (fixed);
  • Wire bonding process (aluminum wedge bonds): $360;
  • Bare die cost: $115 per unit;
  • PCB with ENEPIG surface finish (50x50mm): $590;
  • Packaging and shipping: $50.
  Total costs for a production run of 100 units: $1,615. For higher production volumes, these costs drop significantly, making COB designs a more affordable choice for large-scale manufacturing.

Die with 21 pins for cost analysis

Wire bonding COB design in Altium Designer

Conclusion

Wire bonding remains a crucial technology in modern electronics, offering flexibility and cost-efficiency in a variety of applications, including 3D ICs, power electronics, and COB LEDs. While material and manufacturing costs can vary, especially for high-volume production, the cost advantages of wire bonding become evident as production scales. As technology continues to evolve, wire bonding will remain essential for connecting the next generation of high-performance electronic devices.

Wire Bonding and many new features will be part of the upcoming Altium Designer 25 release, premiering next month. We invite you to join our webinar on this release, titled: Modernizing Engineering Workflows: Altium Designer 25 and the Future of Concurrent Design.

Of course in addition, You can even now start your free trial of Altium Designer + Altium 365 and check how you can upgrade your PCB designs to the next level with Wire Bonding feature.