Production and properties of a spray formed 70% Si-Al alloy for electronic packaging applications

The high silicon content Si-Al alloy is a typical heat dissipation material that used in the electrical packaging field. A spray forming process is used to produce a 70%Si-Al alloy specimen as a heat dissipation material with a diameter of 76.2 rum (3 inch) and a thickness of 6 turn. Then. the spray formed Si-Al alloy specimens are hot pressed at 570 degrees C with different pressure ranged from 200 MPa to 700 MPa to increase their density. The physical properties of the experimental alloy specimen are measured. And the microstructures are observed by using optical microscopy and scanning electronic microscopy. The results show that Spray forming is suitable to produce a 70%Si-Al alloy. The size of primary Si phase in the spray formed 70%Si-Al alloy is refined only 20 similar to 30 mu m. The relative density of 70% Si-Al alloy after spray forming is about 90%. With a following hot pressure of 700 MPa, the relative density value can obtain 98%. The typical physical properties such as the thermal conductivity, coefficient of thermal expansion and electrical conductivity of spray formed 70%Si-Al alloy are acceptable as a heat dissipation material for many electronic packaging applications.