Low temperature bonding method using Cu micro cones

An ideal low temperature bonding method was studied. Cu cones were prepared by electroless plating. Heating and pressure were used in the bonding process between Cu cones and Sn-3.0Ag-0.5Cu solder. It´s a solid state bonding method because the bonding process was performed below the melting point of solder. Shear strength was measured by bonding tester. Morphologies of Cu cones, fracture surfaces and bonding interfaces were analyzed by field emission scanning electron microscope. Results showed that bonding strength was superior with proper bonding conditions. Mechanical interlock produced by insertion was a key success factor. Fast solid state diffusion also played an important role during the bonding process.