Preparation And Properties Of Few-layer H-BN/Copper Composite Materials

With the development of the electronic packaging field toward to high performance,low cost,low density,and integration,the requirements for metal packaging have become higher and higher.Therefore,the requirements for metal packaging materials are also increasing.Copper and copper-based composite materials have been difficult to meet the needs of practical applications.,so it is very urgent to further explore packaging materials with high thermal conductivity and good processing performance.In this paper,few-layer h-BN/Cu composite powders were prwpared by solvothermal method and ball milling method,respectively,based on the characteristics of few-layer hexagonal boron nitride(h-BN)and copper,and few-layer h-BN/Cu composite were prepared by forming and sintering methods.The structure and properties of few-layer h-BN/Cu composite materials prepared by the two methods were studied systematically.A mixture of boric acid and urea was used to prepare h-BN nanosheets with different sheet thicknesses through high-temperature reaction.XRD,Raman,FTIR,and XPS analysis showed that the prepared few-layer h-BN had high purity,and Scanning Electron Microscopy(SEM),Transmission Electron Microscope(TEM)and Atomic Force Microscope(AFM)were used to characterize the microstructure and the sheet thickness of h-BN.By controlling the reaction conditions,the sheet thickness of h-BN can be adjusted.The sheet thickness of h-BN decreases with the increase of urea concentration.The average sheet thickness of h-BN sheet prepared by the mixture of boric acid and urea in a molar ratio of 1:12,1:24,and1:48 were 11-12,5-6,and 1-3 layers,respectively.Few-layer h-BN/Cu composite was prepared by solvothermal reaction of few-layer h-BN,and few-layer h-BN/Cu composite block sample was prepared by vacuum hot pressure sintering technique.The influences few-layer h-BN mass fraction and the sheet thickness of h-BN on the microstructure,thermal conductivity and thermal expansion coefficient of few-layer h-BN/Cu composite were studied.The thermal conductivity of h-BN/Cu composite of average sheet thickness in 1-3,5-6 and 11-12 were 433,428 and 411 W·m^-1·k^-1,respectively.The thermal conductivity of few-layer h-BN/Cu composite with 0,3,6 and 9wt%of h-BN(5-6 sheet thickness)was 391,421,428 and 390 W·m^-1·k^-1,respectively has The low thermal expansion coefficient of few-layer h-BN and it is evenly dispersed in the copper matrix,which makes the thermal expansion coefficient of few-layer h-BN/Cu composite with different mass fractions and different sheet thickness lower than that of pure copper.In order to further improve the thermal conductivity of few-layer h-BN/Cu composite,the interface was modified by introducing Cu₂O into the interface between few-layer h-BN and the copper matrix by hydrothermal method,and then few-layer h-BN/Cu composite were prepared by cold pressure sintering technique,and the influence of interface modification on the microstructure and thermal properties of few-layer h-BN/Cu composite were studied.The thermal conductivity of few-layer h-BN/Cu composite with few-layer h-BN volume fraction of 0,4%and 8%are 383,440 and 452 W·m^-1·k^-1,respectively.After the further introduction of Cu₂O by hydrothermal method,the thermal conductivity of pure copper,few-layer h-BN/Cu composite and few-layer h-BN/Cu₂O/Cu composit were 383,452 and 497 W·m^-1·k^-1,respectively.The introduction of Cu₂O improves the wettability of between few-lyer h-BN with high interfacial energy and the copper matrix,reduces the interfacial thermal resistance at the interface of the two-phase interface,and significantly increases the thermal conductivity of composite.