| Abstract Scope |
Nowadays, with the rise of wearable devices, the chip and circuit design of electronic devices are gradually miniaturized to achieve thin, light, and small products. At the same time, they must have multi-functional applications, fast signal transmission and stable performance in the working environments. Cu-to-Cu bonding technology plays an important role in various kinds of electronic packaging, including Cu-Cu direct bonding, nano/submicron particle sintering, soldering, etc. Process selection is mainly based on the materials and process cost as well as the joint properties, e.g., mechanical properties, thermal conductivity, electrical resistivity. In this article, we fabricated Cu-to-Cu joints by using electroplated Ni UBM and Ga thin films based on thermal compression bonding technology. The effects of Ni/Ga ratios and film thicknesses on interfacial phase transformation will be discussed from cross-sectional elemental analyses. The mechanism of Cu/Ni/Ga/Ni/Cu thermal compression bonding for fabricating Cu-Cu joints will be elaborated. |