No abstract

The interface between the epoxy molding compound and the copper leadframe of an integrated circuit device has been studied by x-ray photoemission spectroscopy (XPS), Auger electron spectroscopy (AES), and secondary electron microscopy (SEM). The surface of the copper frame is composed of CuO, Cu2 O, or Cu(OH)2 depending on the heat treatment for the frame before the molding process. The XPS results show that cuprous oxide is the primary copper oxide at the interface between the leadframe and the epoxy polymeric encapsulant after the molding process. Copper was found to migrate into the epoxy resin side. According to AES and SEM, silica fillers in the molding compound abrade the copper oxide layer on the copper frame during the molding process, and the injected hot epoxy fluid can interact directly with the freshly exposed metallic copper surface. The accelerator of the molding compound segregates to the abraded area at the interface. The rugged interfacial structure close to the molding compound injection gate is probably the primary factor causing the microgap problem at the interface.

To increase the strength and wear resistance of material surfaces, various combinations of B4C and 80TiFe powder were mixed into a Fe60 self-fluxing alloy powder; the composite coatings reinforced by TiB2–TiC were successfully prepared on Q235 steel surfaces by laser cladding. Scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD) were used to study the microstructure and chemical and phase composition. Microhardness and wear testers were used to investigate the mechanical properties. The results show that the interfaces of composite coatings and substrate materials are excellent for metallurgical bonding. The block-like TiB2 particles and flower-like TiC particles are uniformly distributed in the cladding coating. When the mass fraction of the mixed powder is 30%, the average microhardness of the coating is approximately 1100 HV[Formula: see text], which is 50% higher than that without the mixed powder, and demonstrates the best wear with a performance twice as better as that of the substrate.