Moly Copper and Tungsten Copper Properties

Moly copper (MoCu) and tungsten copper (WCu) composites are ideal materials for fabricating heat sinks and heat spreaders. Moly copper and tungsten copper provide the outstanding thermal management properties required by many electronic components. These properties include high hermicity, density, thermal conductivity, and low thermal expansion. Electronic devices in telecommunications, automotive, optical communication, LED, and laser applications increasingly demand efficient thermal dissipating substrates, baseplates, connectors, and other heat spreading components. MoCu and WCu meet this demand across a range of applications, with a variety of performance options.

Moly Copper and Tungsten Copper Surface Wettability

Moly and tungsten copper’s infiltration requires a sintering temperature ranging from 1100-1350 °C. In this range, liquidized copper is more wettable to the tungsten surface than molybdenum. This provides a wider wetting angle for copper to penetrate the tungsten surface. Thermodynamically, it is easier to composite copper with tungsten than with molybdenum. For this reason, suitable MoCu composites require special infiltration sintering treatments to meet required specifications (e.g., homogenous microstructure; good hermicity; and excellent thermal conductivity.

Wetting angle of liquid Cu on Moly copper and tungsten copper

Moly Copper and Tungsten Copper Density and Hardness

In general, the hardness and density of both Molybdenum copper and tungsten copper decrease as their copper content increases. Tungsten copper with a copper volume fraction same as molybdenum copper has a higher density and hardness. Their electrical conductivities and thermal expansion rates go up with the increase of their copper percentage. The density of molybdenum copper is 30% to 50% lower than the density of tungsten copper that has the same percentage of copper. Therefore, this advantage lets MoCu especially desirable for the electronic devices used in weight-sensitive applications such as aerospace and aviation.

The density of W-CU and Mo-Cu alloys

MaterialsHardnessDensityElectrical conductionThermal conduction
(HB)(g/cm2)m/Ω°mm2x102 W/(m°K)

Moly Copper and Tungsten Copper Coefficient of Thermal Expansion

Molybdenum copper (MoCu) has a lower coefficient of thermal expansion (CTE) than tungsten copper (WCu). MoCu’s CTE is linearly 5% to 20% higher than WCu. The CTE increases within a 20-200°C temperature range in proportion to its copper fraction. The CTE difference rises with temperature, reaching a constant of 50% at 500°C.

Moly copper and tungsten copper Coefficient of Thermal Expansion

Moly Copper and Tungsten Copper Specific Heat Capacity

Molybdenum copper has a larger specific heat capacity than tungsten copper. Heat entering or leaving MoCu causes moderate temperature changes in comparison with WCu. MoCu also has a higher thermal spreading rate. These properties give MoCu more performance efficiency and stability during thermal transmission.

Specific heat Cp of Moly copper and tungsten copper

Moly Copper and Tungsten Copper Thermal Conductivity

Moly copper and tungsten copper composites in the same thermal conductivity range exhibit noticeable differences in density and copper fractions. For example, MoCu composite contains less copper. It has half the density of WCu composite with the same thermal conductivity. Moreover, the copper volume fraction of MoCu composites is much smaller than WCu composites with the same density.

Thermal conductivity coefficient curves of Moly copper and tungsten copper

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