A contact probe is a tiny needle-like component used in the inspection of semiconductor products such as IC chips and LEDs. It helps to keep electric connection between semiconductors and the testing devices. In order to ensure consistent and long-lasting use for inspections through tens of thousands of contacts with products, the probes must possess sharp and hard tips, low contact resistance, and high resistance to oxidation.

Probe hardness

R-type and S-type thermocouples are used in high-temperature and atmosphere. These are consisted of pure platinum wire for the negative side and platinum-rhodium alloy wire for the positive side,. While these thermocouples are highly accurate, prolonged use at high temperature coarsens the crystal grains of pure platinum wire, making it susceptible to breakage.
To challenge this problem, we are working to develop a new pure platinum wire. Our new product has about four times stronger high-temperature creep strength in spite of keeping approximately same electromotive force to a conventional pure platinum wire. It has a potential to make thermocouple lifespan extremely longer.
Exposed to high temperature, the grain size of a conventional pure platinum wire easily grows to a size of the wire's diameter. This metallographic structure known as bamboo structure lowers the strength of wire and is the main cause of thermocouple fractures.
Our new pure platinum wire keeps the elongated columnar grains along with the wire drawing direction even under high-temperature conditions. It makes resistances to fracture increase.

The cross-sectional microstructure of the platinum wire after heat treatment

Results of creep testing