Copper And Kovar Bimetallic Wire as conductive lead material

Copper core composite wire 4J29 copper core bimetallic wire is a kind of conductive lead material. It is a kind of bimetallic wire with oxygen free copper in the middle and Kovar, 4j50 or 4J29 and other Kovar alloys are seamlessly sleeved on the outside. It is used for soldering with glass in the manufacture of powerful transistors and relays.

The wire specific resistance is not more than 1.0×10-7 Ohm.m. The wire has a TCLE compliance with C48, C52 glasses. Features good thermal conductivity.

Detailed introduction of copper core composite wire 4J29 copper core wire
 

Specification and size: outer diameter d = 1mm, steel core = 0.45mm (the radius of copper core and low expansion alloy can be any ratio, and the standard ratio is 2:1 and 3:1. When the ratio is 3:1, the resistivity of copper core lead is 12 μ Ω·cm。）

Pure copper, also known as oxygen free high conductivity copper (OFHC), has a resistivity of 1.72 μ Ω· cm, second only to silver. Its thermal conductivity is 401w (m-1k-1).From the perspective of heat transfer, it is very ideal as a package shell and can be used in packages requiring high thermal conductivity and / or high conductivity. However,its thermal expansion coefficient is as high as 16.5 × 10-6k-1 can cause great thermal stress on the rigidly bonded ceramic substrate.

The thermal expansion coefficient of Kovar kovar alloy (Fe29Ni17Co or 4j50 or 4j29) is close to that of Si, GaAs, Al2O3, BeO and ain. It has good weldability and processability, can be matched and sealed with borosilicate hard glass, and is widely used in metal packaging with low power density. The disadvantages are low thermal conductivity, high resistivity and high density.

The copper core composite wire for sealing glass and metal is produced on the basis of Cu. The outer edge of the copper core can be expanded materials such as 50 alloy (Fe-50Ni),kovar alloy (fe-29ni-17co). The two are fully metallurgical combined, with good mechanical strength, toughness and air tightness. It not only provides the high conductivity of copper,but also provides the air tight sealing ability between expanded material and glass.