微合金化对电子封装用高硅铝合金微观组织与性能的影响

采用快速凝固-粉末冶金法制备电子封装用高硅铝合金（Al-50 %Si），研究添加单质Cu粉对微观组织、力学性能和热物理性能的影响.采用扫描电子显微电镜（SEM）、X射线衍射仪（XRD）等手段，分析Cu含量（0~2 %）对微观组织和相组成的影响，并建立与力学性能和热物理性能之间的关系.结果表明:当Cu含量不高于1 %时，高硅铝合金微观组织中Si相尺寸和形貌改变不明显；拉伸强度和抗弯强度均随着Cu含量增加而迅速上升，并在2 %Cu时达到极大值268.4 MPa和422.6 MPa，相对于合金化前提高44.9 %和46.7 %；Cu含量对合金热膨胀系数（CTE）的影响不明显，但是基体中细小的Al₂Cu相不利于导热性能（热导率下降7.5 %）.综上，电子封装用高硅铝合金中添加1 %Cu时，可以在基本保持原有组织和热物理性能的情况下，提高强度20 %以上. 

Effects of microalloying on the microstructure and properties of high-silicon aluminum alloy for electronic packaging

High-silicon aluminum alloy (Al-50 %Si) for electronic packaging was prepared by rapid solidification and powder metallurgy. Effects of the added elemental copper powder were investigated on the microstructure, mechanical and thermo-physical properties of the alloy. The microstructure and phase composition of the alloy containing different copper contents (0~2 %) were studied by SEM and XRD, and the relationship between copper content and the mechanical and thermo-physical properties was established. The results showed that the size and morphology of Si phase in the microstructure of the alloy changed slightly when the content of copper was less than 1 %. Tensile strength and bending strength increased obviously with the increase of copper content and reached a maximum value of 268.4 MPa and 422.6 MPa, respectively. When the copper content reached 2 %, increased by 44.9 % and 46.7 %, respectively, compared with that without copper. The addition of copper had no obvious effect on coefficient of thermal expansion (CTE) of the alloy. However, the small Al₂Cu phase distributed in the matrix reduced the thermal conductivity by 7.5 %. In summary, with the addition of 1 % copper, the high-silicon aluminum alloy for electronic packaging improved its strength by more than 20 % while maintaining a relatively high thermal conductivity.