Effects of rolling and annealing on microstructures and properties of Cu/Invar electronic packaging composites prepared by powder metallurgy
(1. School of Materials Science and Engineering, Hefei University of Technology, Hefei 230009, China;
2. 43 Institute, China Electronics Technology Group Corporation, Hefei 230088, China;
3. Key Laboratory of Functional Materials and Devices of Anhui Province,
Heifei University of Technology, Hefei 230009, China)
2. 43 Institute, China Electronics Technology Group Corporation, Hefei 230088, China;
3. Key Laboratory of Functional Materials and Devices of Anhui Province,
Heifei University of Technology, Hefei 230009, China)
Abstract: The Cu/Invar composites of 40% Cu were prepared by powder metallurgy, and the composites were rolled with 70% reduction and subsequently annealed at 750 °C. Phases, microstructures and properties of the composites were then studied. After that, the amount of α-Fe(Ni,Co) in the composites is reduced, because α-Fe(Ni,Co) partly transfers into γ-Fe(Ni,Co) through the diffusion of the Ni atoms into α-Fe(Ni,Co) from Cu. When the rolling reduction is less than 40%, the deformation of Cu takes place, resulting in the movement of the Invar particles and the seaming of the pores. When the rolling reduction is in the range from 40% to 60%, the deformations of Invar and Cu occur simultaneously to form a streamline structure. After rolling till 70% and subsequent annealing, the Cu/Invar composites have fine comprehensive properties with a relative density of 98.6%, a tensile strength of 360 MPa, an elongation rate of 50%, a thermal conductivity of 25.42 W/(m·K) (as-tested) and a CTE of 10.79×10-6 /K (20-100 °C).
Key words: electronic packaging material; Cu/Invar composite; rolling; annealing