Search

Diamond/Cu composites fabricated via the traditional powder metallurgy method show low thermal conductivities due to the poor wettability between diamond and Cu matrix. The fabrication method adopted in this study provides a simple and low-cost method for producing diamond/metal composites. Thermal properties of the diamond/Cu–Ti composites fabricated by pressureless sintering at 1373 K for 30 min with variation in diamond particle sizes and volume fractions were thoroughly investigated. The composites produced in this study exhibited thermal conductivity as high as 608 W/m K for 60 vol.% bimodal diamond/Cu-2 at.% Ti composite comprised of 50 vol.% diamond particles with the size of 300 μm and 10 vol.% diamond particles with the size of 150 μm. A suitable coefficient of thermal expansion of 5.4 × 10 −6 1/K was obtained. This thermal conductivity value comes up to 92% of the thermal conductivity calculated by Hasselman and Johnson model combining with diffuse mismatch model. The predicted value from this model is in good agreement with the experimental value. Furthermore, the pressureless sintering is a simple technique that requires only low-cost equipment, making this cost-effective method attractive for metal matrix composite fabrication.

Diamond/Ag–Ti composites were fabricated by a low-cost liquid sintering technique. The Ti addition can effectively improve wetting and promote penetration in composite pores during liquid sintering. The interface structure of the diamond/Ag–Ti composite was identified as Ag/TiC/Ag–Ti/diamond. A high thermal conductivity of 719 W/mK was obtained for the 50 vol.% diamond/Ag-1 at.% Ti composite. Using a bimodal mixture (60 vol.% 150 μm + 10 vol.% 50 μm diamond/Ag-2 at.% Ti composite), a low coefficient of thermal expansion of 6.3 × 10 − 6 /K still with high thermal conductivity of 687 W/mK was achieved. These composites have potential applications for thermal management of high integration electronic devices.

Thermal management in microelectronic technology has become an important issue due to the increase of device power and integration levels. Diamond and silver were selected for the fabrication of composites with high thermal conductivity and low coefficient of thermal expansion (CTE). Diamond reinforcement powders with varied types, shapes and sizes were electroless plated by silver. Then these powders were hot-pressed in air at 600 °C, 500 MPa for 30 min to produce bulk silver matrix composites. The thermal conductivity and the CTEs of the composite at 20 vol.% are 420 W/m K and 12 ppm/K, respectively. These diamond/Ag composites have potential applications for the high integration electronic devices.

Diamond/Ag–Ti composites were fabricated by a low-cost vacuum liquid sintering technique and the effects of Ti addition on the thermal properties of the composites were studied. The results indicate that the optimal quantity of added Ti is 3 at%. Adding less than 3 at% Ti resulted in poor wettability, while adding more than 3 at% Ti resulted in excessive formation of TiC. Both reduced thermal conductivity. A composite comprising 60 vol% diamond/Ag–3at%Ti resulted in a maximum thermal conductivity of 836 W m −1 K −1 with a coefficient of thermal expansion of 5.6×10 −6 K −1 . These composites are excellent candidates for the thermal management of integrated electronic devices.

In this study, minor-addition elements such as Si, Co, Cr, W, Mo, and Ti were added to matrix to improve the wettability between the diamonds and Cu matrix. The pressureless liquid-phase sintering technique adopted in this study provides a low-cost method for producing diamond/Cu composites with high potential for industrial mass production. Thermal properties of the diamond/Cu-Ti composites fabricated by pressureless liquid-phase sintering at 1373 K with variation in Ti contents were thoroughly investigated. XRD and TEM analysis show that TiC layer formed in the interface between Cu and diamond. The composites exhibited thermal conductivity as high as 620 W/m·K for 50 vol% diamond/Cu-0.6 at % Ti composite with diamond particle size of 300 µm. This value comes up to 85% of the thermal conductivity calculated by the Hasselman and Johnson (H-J) theoretical analysis. Under these conditions, a suitable coefficient of thermal expansion of 6.9 ppm/K was obtained.