Modification On Diamond Surface And Preparation And Research Of Thermal Composites

With the continuous developing of electronic technology, The requirements of electronic packaging materials for the electronics industry is increasing, and traditional electronic packaging materials for semiconductor devices can not meet the requirements for electronic packaging materials. Diamond/metal composites is one of the most promising electronic packaging materials, which have high thermal conductivity and thermal expansion coefficient can be regulated, for combining the excellent characteristics of diamond reinforcement and metal. Today, the cost of diamond has been reduced greatly as artificial diamond had been industrialization. It provides a good foundation for the widely application of diamond/metal matrix composite materials. So it is significant ive and practical for the study of diamond/metal composites with high thermal conductivity.In this paper, we used two different surface modification methods to modify the surface of diamond particles. Scanning electron microscopy, Raman spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy and other test techniques have been used to analysis and research the micro morphology and structure of the surface of diamond particlesWe have prepared diamond-graphene nanowalls/Al composites, diamond-B/Cu composites and diamond-Si/Cu composites with different vacuum hot pressing process. We have analysis the micro morphology of the fracture surface of composites with Scanning electron microscopy, and we have tested the thermal diffusivity of composites with laser thermal conductivity meter. Last, we analyzed the influence of the volume fraction of diamond particles and three different diamond surface modification methods on composite material thermal conductivity. The main conclusions are as follows:(1) Graphite elements Fe and Ni corresponding reduced iron and nickel powder are used to modify diamond surface with high temperature blending process to grow graphene nanowalls on the surface of diamond particles. When the modified treatment temperature was 1200 ℃, graphene nanowalls have completely covered the surface of diamond particles. When the modified temperature reaches 1400 ℃, parts of the diamond particles surface have been graphited. Diamond- graphene nanowalls /Al composites were prepared after the modification of diamond particls, and the thermal conductivity of composites reaches 423 W/(m·K) when the diamond powders were coved by grapheme nanowalls which greatly increase the contact area between diamond and aluminum.(2) Amorphous boron powders were used to modify diamond surface with high temperature blending process to plate uniform boron plating layer on diamond particles surface. Bath method was used to plate uniform silicon layer on diamond powders surface. Diamond powders plated with silicon layer were mixed with high-purity copper. And then we prepared diamond-graphene nanowalls/Al composites with different vacuum hot pressing process parameters to determine the best process parameters. High-purity copper powder is mixed with each of the two modified pretreated diamond particles. And then the process parameters were used to prepared diamond-B/Cu composites with different diamond volume fractions and diamond-Si/Cu composites with different diamond volume fractions. The highest thermal conductivity of diamond-B/Cu composites reaches 474 W/(m·K), and the highest thermal conductivity of diamond-Si/Cu composites reaches 501 W/(m·K).