| The rapid development of the electronic information industry has led to higher and higher integration of electronic devices.Traditional heat dissipation materials are difficult to meet the heat dissipation requirements under high heat flux.It is imminent to develop a new generation of new heat dissipation materials with high thermal conductivity.This paper investigates the research and application status of common thermal conductive materials in the field of electronic packaging,and proposes a research idea for applying cubic boron nitride(c BN)to the field of thermal conductivity;successfully prepares c BN composites under the condition of high temperature and high pressure by using domestic six-sided jacking press;systematically studies the effects of phase system,phase content,sintering temperature and c BN particle size on the properties of the composites.The main results are as follows:(1)In the study of c BN/Al N system composites,20 wt.% is the optimum Al N content,and 1500℃ is the optimum sintering temperature.Under the above conditions,when the c BN particle size is 15 μm-25 μm,the relative density of the composite reaches the maximum(98.2%).when the c BN particle size is 22 μm-36 μm,the thermal conductivity of the composite reaches the maximum value of 88 W/(m·K),and the relative density of the composite is 97.8%.(2)In the study of c BN/Al N/Al system composites,20 wt.% is the best addition of binder.The relative density and thermal conductivity of the composites increased as the sintering temperature increased.When the sintering temperature is 1500℃,the relative density and thermal conductivity of the composites reach 98.8% and 96 W/(m·K),which is 1.02% and9.09% higher than that of the c BN/Al N system composites prepared under the same conditions.(3)In the study of c BN/Al system composites,when the sintering temperature is 1300℃and the Al addition is 30 wt.%,the c BN/Al composite achieves the best comprehensive performance,its relative density is 98.6%,and the thermal conductivity reaches 198 W/(m·K).The relative density and thermal conductivity of diamond/Al prepared under the same conditions are only 92.4% and 136 W/(m·K).(4)The thermal conductivity of c BN/Al composites decreases continuously with the increase of the thickness of the interface layer,which is confirmed by the study of the thermal conductivity theory of composite by the phonon mismatch model and the Hasselman-Johnson model.However,due to the fact that the compactness of the composite and the uniform distribution of the interfacial layer are not considered in the theoretical study,there are some deviations from the actual results.(5)A gradient c BN/Al composite model was designed.Two different heat conduction models are constructed according to the difference between chip heat source area and substrate area.The research on the change of the total thermal resistance of the substrate with the size of the substrate shows that the total thermal resistance of the substrate decreases first and then increases with the thickness of the substrate,and increases with the increase of the substrate radius. |
