Optimizing On Component And Preparation Technology Of High-Strength And High-Conductivity Copper Alloys

With the development of the electronic industry, the large scale integrated circuit lead frame material of the ideal performance are required:tensile strengthσb >600MPa,micro hardness HV>180,electronic conductivityσ>80%IACS, softening temperature T>500℃.The researchers have developed high-strength and high-conductivity copper base materials from the respects of deformation strengthening,solid solution strengthening,precipitation strengthening,the grain boundary strengthening and composite strengthening. In order to obtain ideal target properties mentioned above, the establishment of a Chinese independent high strength and high conductivity copper alloy material system is imperative.In this paper, the influence on microstructure and properties of high conductivity copper alloy composition design, melting and heat treatment has been systematically studied.On this basis, the final alloys are excellent overall performance by optimizing alloy composition and process. The results are as follows:(1)A more uniform microstructure and properties were obtained and the segregation of the alloy composition was reduced by adopting greater cooling rate when the copper alloy melt solidified.It should reduce the temperature of melt before the casting, then hot-line casting, casting speed should be slow, in the whole process,slightly faster after using the first delay and then slow down the speed of the final casting, it could obtain more uniform texture, more compact and lighter piped of the copper alloys casting rods.(2) The study of the alloy composition shows:addition of rare earth Y contrast to addition of rare earth Nd could get higher alloy' hardness and more stable performance and more uniform microstructure.Excellent mechanical and electrical comprehensive performances were obtained when precipitation strengthening elements Cr was 0.8wt%.Zr element could obvious improve the microstructure, refine the grain boundary and reduced the Cu-Cr eutectic structure, increased the hardness and improve the thermal stability of the alloy, when addition content of Zr element was 0.2wt%.Two types alloy composition with excellent performance were obtained, the one was Cu-0.8Cr-0.05Y(wt%) alloy and the another was Cu-0.8Cr-0.2Zr-0.05Y(wt%) alloy. The former one had slightly lower hardness but higher conductivity than the later.(3) The deformation amount was inadequate when the alloy deformation amount was 70%.When the deformation amount increased to 90%, the grains were obvious elongated, defects such as vacancies and dislocations were increased to offer more precipitation channels for the solid solution atoms, and helped solid solution atoms precipitating at post aging,the precipitation strengthening effect was obvious.(4) An excellent preparation craft were got by studying the influence on alloys microstructure and properties of solid solution technology in the heat treatment, aging temperature and aging time. Cu-0.8Cr-0.05Y with 90% deformation +480℃×12min aging treatment, had excellent comprehensive performance with the hardness of 176HV, tensile strength of 540MPa, conductivity of 84.8%IACS,softening temperature of 525±5℃.Cu-0.8Cr-0.2Zr-0.05Y with 90% deformation +500℃×60min aging treatment, had excellent comprehensive performance with the hardness of 194HV, tensile strength of 552MPa, conductivity of 83.3%IACS, softening temperature of 580±5℃.