Providing cutting-edge materials derived from precious metals to help shape the future of semiconductor devices

Next-Generation Power Semiconductors Are Rapidly Becoming Widespread

If logic semiconductors and memory semiconductors are considered the brain, then power semiconductors can be likened to the heart. Power semiconductors control and supply electricity and are found in all electronic devices. They are particularly important components in electric vehicles (EVs), industrial equipment, communication base stations, and renewable energy, which use large amounts of electric power, and the market is expected to continue to grow in the future. We are also accelerating the development of new technologies with the aim of reducing energy consumption.

Power semiconductors with wide bandgap are rapidly being adopted to ensure stable operation even in harsh environments. Compared to conventional silicon-based semiconductors, those using silicon carbide (SiC) and gallium nitride (GaN) can maintain their performance under high temperature conditions while maintaining stability, and have superior high power and high frequency, and development is underway toward mass production.

However, designers are facing new challenges in developing next-generation power semiconductors, according to Mr. Fushimi of TANAKA PRECIOUS METAL TECHNOLOGIES. "These include the need to cope with high heat due to increased power capacity, maintain bonding reliability over thousands of thermal cycles, and bond chips (dies) with large areas as they become larger. It has become increasingly difficult for conventional solder pastes and epoxy resin adhesives to meet these requirements."

Solving challenges through materials for flexible module design

TANAKA provides materials that address these challenges. One of them is Ag Adhesive, which changes die bonding. The resin-reinforced sintered silver (commonly known as Hybrid Sintered Silver) developed by TANAKA is a material that stands apart from conventional sintered silver. "In addition to excellent heat dissipation due to high thermal conductivity, it has high reliability under thermal cycling thanks to a unique resin system, and can meet the harsh environmental requirements of automotive applications" (Fushimi). This product is particularly effective for small- to medium-sized die bonding and, according to Fushimi, contributes to extending the lifespan and increasing the capacity of power devices.

The other is “AgSnTLP Sheet,” which is ideal for bonding large areas. “This is a bonding sheet for Ag-Sn transient liquid phase diffusion bonding that is effective for bonding large-sized dies and entire modules,” explains Shinichiro Kitaoka of the company involved in its development.

This bonding sheet has three main Features. The first is reliability. After bonding, the heat resistance temperature of this bonding sheet rises to 480℃ as Ag (silver) and Sn (tin) form Ag3Sn. Therefore, it has higher heat resistance than existing materials. It has a maximum bonding strength of 50 MPa and maintains similar bonding strength even at 300℃. It has also passed 3000 cycles of thermal cycle tests. The second is cost reduction. Bonding can be completed in a few minutes, which can reduce process costs by reducing takt time. The third is reduced environmental impact. This material does not contain solvents, so it does not emit VOCs (volatile organic compounds). In addition, it does not contain substances regulated by RoHS. "This bonding sheet has a process that can reliably bond even at low pressures, as well as reduced voids and simplified manufacturing processes. It is particularly suitable for large bonding surfaces between modules and heat sinks, and is expected to improve heat dissipation" (Kitaoka).

The two solutions, Ag Adhesive and AgSn TLP Sheet, for die bonding are complementary. Their true value can be realized by using them selectively according to their respective characteristics. For example, Ag Adhesive is suitable for die bonding of small to medium-sized dies, while AgSn TLP Sheet is suitable for bonding of large-area dies where thermal stability is required. By using both solutions in a complementary manner, the freedom of module design, which was previously difficult, can be expanded, and the three elements—thermal management, reliability, and manufacturability—essential for the development of next-generation power semiconductors can be improved simultaneously.

A full lineup of materials from upstream to downstream

As exemplified by EVs, power semiconductors have increasingly required the ability to control electricity even in relatively small spaces. In order to miniaturize power semiconductors while simultaneously improving their performance, there is a growing need for "low resistance" and "heat dissipation" in the materials used for power semiconductors.

TANAKA provides total solutions for products for power devices. In addition to die bonding materials, TANAKA stably supplies a full lineup of materials from upstream to downstream of the manufacturing process, including bonding wires that are among the world's top in terms of supply volume, precious metal brazing filler metals, plating processes, and sputtering targets.

In addition, since precious metals are often rare, we consider the systems for producing and distributing precious metal materials with recycling in mind. At TANAKA, precious metal recycling is one of our core businesses, and we are promoting the global expansion of our recycling sites.

As power semiconductors evolve, innovations in bonding materials are essential to address the challenges of heat dissipation and reliability. TANAKA is at the forefront of this field and is ready to support power electronics in a new era.
TANAKA will continue to utilize the properties of precious metals in its research, development, and provision of advanced materials.

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Latest Trends in Power Semiconductor Packaging Technology and Cutting-Edge Materials for High Heat Dissipation and High Heat Resistance
As energy-saving technologies for smartphones and electronic devices, next-generation mobility such as electric vehicles, base stations, and power control for renewable energy continue to advance, the technological development of power semiconductors will increasingly focus on higher output and efficiency.
We will introduce cutting-edge materials to address challenges such as high heat dissipation, high heat resistance, bonding reliability, and miniaturization, as well as trends in packaging technology.

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