What is the Expansion Alloy 4J29 used in MIM? What are its Main Applications?

Date：2025-08-04   Views：1002

4J29 alloy (also known as Kovar alloy) is a low-expansion alloy based on iron, nickel, and cobalt (Fe-Ni-Co), used in the MIM process to manufacture high-precision, complex-shaped electronic packaging components. 

Its core characteristic is its high thermal expansion coefficient matching with specific glass materials, making it a key material for glass-to-metal sealing (GTMS). The primary application of 4J29 alloy is as a glass sealing structural material, enabling vacuum sealing of electronic devices and the extraction of electrical signals.

Typical application areas of 4J29 (with MIM)

• Electro-vacuum devices: transistor housings, integrated circuit lead frames.

• Aerospace: satellite navigation components, rocket engine sensor seals.

• New energy and communications: microwave filters, antenna sealing bases.