Preparation Of High Silicon Aluminum Alloy Electronic Packaging Materials And 3D Printing Process Research

High silicon aluminum alloy material has low density,low thermal expansion coefficient and high thermal conductivity.It is a light and environmentally friendly electronic packaging material.With the development of modern science and technology,the requirements for electronic packaging materials tend to be high quality,high complexity and miniaturization.The traditional preparation process has been unable to meet the current requirements of electronic packaging materials.The selective laser melting(SLM)technology not only solves the problem that the traditional preparation process is difficult to process complex parts,but also solves the problem that the traditional preparation process is difficult to control.However,the preparation of high silicon aluminum alloy electronic packaging materials by SLM technology started late,and the research on SLM technology is not yet mature.Therefore,Al-50Si alloy powder is selected as the raw material of SLM technology in this paper.The key process parameters of SLM are systematically analyzed,and the influence of SLM technology on high silicon aluminum alloy materials is discussed.Al-60Si alloy powder was prepared by mechanical alloying technology,and Al-60 Si alloy sample was prepared by SLM.The specific research contents are as follows:Al-50Si alloy samples were prepared by selective laser melting technology,and the effects of laser power and laser scanning speed on the density and hardness of the samples were studied.With the increase of laser scanning speed(1200-2000mm/s),the density and hardness of the sample show an increasing trend.The laser power has little effect on the density and hardness of the sample within 290-350W.When the laser power is290W(laser scanning speed is 2000mm/s,scanning distance is 0.09mm),the density of the alloy can reach 98.13%,and the hardness is 160.96HV.At the same laser power,when the scanning speed decreases to 1200mm/s,the alloy sample has the lowest density of94.34%and the hardness of 147.42HV.Al-60Si alloy powder was prepared by mechanical alloying using Al-50Si powder and Si powder as raw materials.The main process parameters of mechanical alloying technology were studied by orthogonal experiment,and Al-60Si alloy powder was prepared.Through the analysis of the results,the ball milling speed is the main factor affecting the particle size of the powder in the selected mechanical alloying process parameters.When the ball milling speed is 180r/min(ball milling time is 14h,ball material ratio is 5:1),the particle size of Al-60Si powder is 17.651μm,and the powder distribution is uniform,which can be used to form Al-60Si alloy by SLM technology.Al-60Si alloy samples were prepared by SLM with Al-60Si powder optimized by mechanical alloying process parameters as the raw material of selective laser melting technology.The effect of laser energy density on the formability of Al-60Si alloy was studied.When the laser energy density is reduced to 134.26J/mm~3,the relative density of Al-60Si alloy sample is up to 95.74%,and no other defects are found in the sample except for a small amount of pores.With the increase of Si content,the thermal expansion coefficient and thermal conductivity of Al-60Si decrease.The measured values of thermal expansion coefficient of Al-50Si alloy and Al-60Si alloy are higher than the predicted values of theoretical model,and the measured values of thermal conductivity of materials are significantly lower than the theoretical values.The increase of Si content with low expansion coefficient and low thermal conductivity reduces the thermal expansion coefficient and thermal conductivity of high silicon aluminum alloy.The theoretical model ignores the internal pores of the material and the morphology of the reinforcing phase,so the thermal expansion coefficient is lower than the measured value,and the thermal conductivity is higher than the measured value.