Interface Optimization And Surface Modification Of Diamond Composite Thermal Conductive Material

Electronic packaging requires high thermal conductivity and proper thermal expansion coefficient to meet the requirements of electronic products.The best choices for the new generation of electronic packaging materials was diamond/copper composites,but the interface bond strength and thermal conductivity of composites made by traditional methods were low,which could not meet the application requirements.In this paper,the Ti,Cr and Si coatings were plated on the surface of diamond particles by vacuum micro-evaporation plating and spark plasma plating method,and the phase,morphology,thickness and interface structure of the coatings were analyzed and characterized.The influence mechanism of temperature and time factors on the quality and performance was studied.The diamond/copper composites were prepared by spark plasma sintering method,the phase composition and the microstructure of the composites were characterized,the actual thermal conductivity and theoretical thermal conductivity were calculated,and the influence law of coating types on the microstructure and thermal conductivity performance was analyzed.Moreover,because of the poor heat resistance of resin-bonded diamond tooling,the thermal shock resistance of resin-bonded diamond tooling has been reduced by metallizing the diamond surface.However,it was difficult to metallize the surface of diamonds with fine grain size(< 7 μm).this paper used aluminum borosilicate binder to granulate 1～2 μm particle diamond into larger agglomerated particles,and the phase composition,micro-morphology and flexural strength of agglomerated particles were tested.The results were showed as follows:(1)The Ti coating was planted at 750 °C for 1 h by vacuum micro-evaporation plating method.And the thickness of Ti coating was 375 nm.The Ti-coated diamond/Cu composites were sintered at 900 °C for 20 min by spark plasma sintering method.The best thermal conductivity of the Ti-coated diamond/Cu composite was 330 W/(m·K),which was 66.67%higher than that of the diamond/Cu composite.(2)The Cr coating was planted at 850 °C for 2 h by vacuum micro-evaporation plating method.And the thickness of Cr coating was 644 nm.The Cr-coated diamond/Cu composites were sintered at 900 °C for 20 min by spark plasma sintering method.The best thermal conductivity of the Cr-coated diamond/Cu composite was 326 W/(m·K),which was 64.65%higher than that of the diamond/Cu composite.The thermal conductivity of the Cr-coated diamond/Cu composites were lower than the thermal conductivity of the Ti-coated diamond/Cu composites.(3)The Si coating was planted at 1250 °C for 40 min by spark plasma sintering method.The FESEM result showed that an integral Si coating layer was formed on diamond surface.The thickness of Si coating was about 109 nm by calculated.The thermal conductivity of the Si-coated diamond/Cu composites increased as the sintering temperature.The best thermal conductivity of the composite was 455 W/(m·K),which was 129.80% higher than that of diamond/copper composite material without surface treatment.The thermal conductivity of diamond/copper composites were significantly improved by Si coating compared to Ti coating or Cr coating.(4)Ceramic binders with Si or Ti additives can effectively aggregate diamond particles.When the weight percent of Si and Ti were 10%,the agglomerated abrasive had the highest bending strength.The aggregated abrasives with Si additive had larger particle size than that of samples with Ti additive.1～2 μm diamond particles could be aggregated into 5～10 μm particles.