Copper-tungsten (WCu): heat sinks, contacts & electrodes
Why copper-tungsten conducts heat like copper yet stays temperature-stable like tungsten – properties, grades (W80Cu20 etc.) and applications.
Copper-tungsten (WCu) is a composite of a tungsten skeleton infiltrated with copper. It combines tungsten’s high temperature resistance and low coefficient of thermal expansion with copper’s excellent thermal and electrical conductivity.
How WCu works
Tungsten forms a porous skeleton whose voids are filled with copper. The mix ratio tunes the properties: more tungsten means lower thermal expansion and higher temperature resistance, more copper means better conductivity.
Common grades
Grades are usually named by tungsten content, e.g. W80Cu20, W75Cu25 or W70Cu30 (number = weight fraction). A high tungsten content is chosen for dimensionally stable, low-expansion parts; a higher copper content where maximum heat and current conduction matter most.
Heat sinks and spreaders
In electronics WCu is used as a heat spreader because its coefficient of thermal expansion can be matched to semiconductors and ceramics. This reduces thermal stress at the joints – important for power electronics, laser diodes and RF components.
Contacts and electrodes
Thanks to its arc and erosion resistance, WCu also serves as a material for electrical contacts in high-voltage switchgear and as an electrode for electrical discharge machining (EDM), where shape retention and low wear matter.
Frequently asked questions
Why not just use pure copper for heat sinks?
Pure copper conducts better but expands a lot. WCu can be matched in thermal expansion to semiconductors and ceramics, avoiding thermal stress at the joints.
What does W80Cu20 mean?
The material is about 80% tungsten and 20% copper (by weight). The higher the tungsten content, the lower the thermal expansion.
What else is WCu used for besides heat sinks?
For electrical contacts in high-voltage switchgear and as erosion-resistant electrodes for electrical discharge machining (EDM).
Is WCu easy to machine?
WCu can be machined but is harder than pure copper due to its high tungsten content. For tight tolerances, carbide tooling or EDM is recommended.
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