Hard and Flexible: New Palladium-Based Alloy Will Simplify Testing of Microelectronic Equipment

The Japanese company TANAKA has unveiled its latest innovation—TK-SK, a new palladium-based alloy designed for manufacturing probe pins (Probe Pins) used in the final stages of printed circuit board (PCB) testing. This advanced material was presented at the SWTest Asia 2024 conference held on October 24–25, 2024, in Fukuoka Prefecture, Japan. Initial samples of products made from the TK-SK alloy will be available by the end of the year. With this innovative development, TANAKA aims to boost its electronic components sales by 1.5 times within the next three years.

The TK-SK alloy boasts an impressive hardness rating of 640 HV (HV means Vickers hardness, see box). This places it at the forefront of the electronic testing connectors market. While TANAKA offers around ten different alloys for manufacturing probe pins, most exhibit hardness levels ranging between 300–400 HV, with a few reaching 500–550 HV. The maximum previously achievable hardness was 560 HV, making TK-SK the hardest alloy in the company’s portfolio.

By developing a high-hardness alloy, TANAKA has achieved a significant milestone in materials science. The exceptional hardness of TK-SK ensures that probe pins retain their shape, delivering reliable and stable contact with tested objects—essential for precise electrical parameter measurements in semiconductors. 

A unique feature of TK-SK is its bending resistance. Probe pins made from this alloy withstand up to ten repeated bends (based on TANAKA’s internal standards) without breaking. This combination of extreme hardness and flexibility is unprecedented, as hard materials are typically brittle. 

The alloy’s composition includes 48.9% palladium and 19.25% silver, along with copper and other metals. The addition of silver and copper enhances flexibility and electrical conductivity while maintaining exceptional wear resistance.

The introduction of TK-SK paves the way for creating precise, thin, and lightweight probe pin designs, expanding testing possibilities for smaller circuit boards. This innovation is crucial for modern microelectronics, where each new generation of devices is more compact than the last.

The high hardness of TK-SK also addresses a common issue with Pogo pin contact probes: wear and deformation. During frequent use, these pins are prone to damage from friction and solder adhesion, necessitating regular maintenance.

The remarkable wear resistance of TK-SK not only extends the lifespan of contact probes but also reduces the maintenance costs of expensive testing equipment. This alloy is poised to play a pivotal role in the semiconductor industry’s transition to a new technological paradigm. While currently positioned as a material for probe pins, the TK-SK alloy is expected to be adapted for a broader range of applications in the coming years, similar to the trajectory of TANAKA’s previous flagship palladium alloy, TK-FS (Vickers hardness: 400–520 HV).

Palladium Base of Contacts in Microelectronics

Materials with a hardness of 640 HV are not new to humanity. High-carbon and alloy steels, ceramics, and carbide-based materials have long been used in tooling and mechanical components. These materials are wear-resistant and maintain their shape under heavy mechanical loads.

However, such materials—especially steels with high electrical resistance or non-conductive ceramics—are unsuitable for electronics. The TK-SK alloy’s palladium base enables a unique combination of mechanical durability, excellent conductivity (≤7.0 μΩ·cm), and chemical stability.

Few metals, even precious ones, are suitable for manufacture of strong, flexible and current-conductive materials. Copper, silver and gold have the perfect electrical conductivity but they are very soft, and connections and contacts made of these metals are easily worn. This is why engineers use palladium as the base for microelectronic devices. The combination of resistance to corrosion, high melting point and electrical conductivity makes it perfect for conductors and ensures reliable and efficient connections within the printed circuit boards and between them. At the same time, palladium is hard and has lower density which means that 1 milligram of the metal takes up a volume larger than, for example, 1 milligram of gold.

Out of TANAKA’s ten palladium-based alloys for microelectronics contacts, six have palladium contents ranging from 33% to 56%. These alloys include other metals such as gold, platinum, silver, and copper, making them solderable and versatile for various applications

Palladium is also used to alloy other materials, such as semiconductor contact pads. This enables the creation of thin, high-quality metal layers that improve electrical performance and contact stability—crucial for high-frequency and high-speed circuits.

The Secret Bureau

The demand for high-hardness sensor pins has been growing recently; but as the hardness increases, material processing becomes even harder due to equipment breaking during cutting, for example. This is why creation of a new alloy is not enough – a procedure is needed for its processing and for manufacture of products unique in terms of accuracy and subtlety.

For example, producing TK-SK probe pins requires ultra-thin wire (≤0.5 mm) from the alloy, which demands cutting-edge equipment capable of withstanding the alloy’s hardness. Processes such as cutting and polishing must meet microscopic precision standards, as pogo pins are tiny components with exacting requirements.

Few companies worldwide possess the expertise, technology, and tools necessary to achieve this—TANAKA is one of them.

Source: https://tanaka-preciousmetals.com/en/news_release/20241017/