No abstract

No abstract

No abstract

No abstract

No abstract

Specimens with the Sn/Cu/Sn/Ni/Sn/Cu/Sn structure reacted at 200°C are prepared and examined. The Cu 6 Sn 5 and Cu 3 Sn phases are formed at the Sn/Cu interface, and the Cu 6 Sn 5 and Ni 3 Sn 4 phases at the Sn/Ni interface. The reaction path in the original Cu/Sn/Ni part of the specimen is Cu/Cu 3 Sn/Cu 6 Sn 5 / Sn/Cu 6 Sn 5 /Ni 3 Sn 4 /Ni. The peculiar phenomenon of the Cu 6 Sn 5 phase forming at both sides of the Sn phase is illustrated using the Sn-Cu-Ni phase diagram with a very wide compositional-homogeneity range of the Cu 6 Sn 5 phase. Interfacial reactions at 240°C between pure Sn and (Cu,Ni) alloys of various compositions are determined. The Cu 6 Sn 5 phase is formed when the Ni content is less than 30 wt.%, and the Ni 3 Sn 4 phase is formed when the Ni content is higher than 40 wt.%. When the Ni content is between 35 wt.% and 40 wt.%, both Cu 6 Sn 5 and Ni 3 Sn 4 phases are formed. It is also noticed that the formation of the Cu 3 Sn phase at the Sn/(Cu,Ni) interface is suppressed with more than 1wt.%Ni addition in the substrate.

Copper metallization on polyimide films was carried out via a wet chemical process. This process included the chemical reaction of KOH with PI to form poly(amic acid) (PAA), ion exchange of doped K(+) with Cu(2+) to form Cu(2+)-doped PAA, doped Cu(2+) reduction by aqueous dimethylamine borane (DMAB) to form copper nanoparticles (CNPs) on PAA, and electroless copper (ELC) deposition catalyzed by CNPs on PAA. An organic additive, namely, bis(3-sulfopropyl)-disulfide (SPS), that can effectively reduce the size of CNPs and significantly enhance the chemical activity of CNPs for ELC deposition was used in this work. For comparison, doped Cu(2+) ions in the PAA were also reduced by hydrogen gas at 350 degrees C. The results show that only aqueous reductants can induce the reduced copper atoms to aggregate on the PAA surface and to form a granular copper layer that acts as a catalyst for the ELC deposition. Mechanisms for the aggregation of copper atoms and for activity enhancement of the CNPs due to SPS addition in the DMAB solution are proposed according to the evidence obtained from Fourier transform infrared spectrometry (FTIR), X-ray photoelectron spectrometry (XPS), field emission scanning electron microscopy (FESEM), cross-sectional transmission electron microscopy (TEM), and atomic force microscopy (AFM). The CNP-coated PAA films and the structures of the ELC deposits were characterized by X-ray diffraction (XRD) and UV-visible spectrophotometry (UV-Vis), respectively

Sn–Zn-based alloys are promising low melting-point Pb-free solders, and it has been reported that their wetting properties and oxidation resistance can be improved with the addition of Cu. The interfacial reactions in the Sn–9 wt% Zn–xCu/Cu couples at 250 °C and Sn–9 wt% Zn–xCu/Ni at 280 °C were examined in this study. A thick γ–Cu5Zn8 phase layer and a very thin β′–CuZn phase layer were formed in both the Sn–9 wt% Zn/Cu and the Sn–9 wt% Zn–1 wt% Cu/Cu couples. The γ–Ni5Zn21 phase layer was formed in both the Sn–9 wt% Zn/Ni and Sn–9 wt% Zn–1 wt% Cu/Ni couples. With longer reaction time, the δ–Ni3Sn4 phase were formed in the Sn–9 wt% Zn/Ni couple as well. In both the Cu and Ni couples, the Zn-containing γ phases were uniform and planar and were the dominant reaction products. However, when the Cu content of the Sn–9 wt% Zn–xCu solders was 10 wt%, the interfacial reaction product becomes the η–Cu6Sn5 phase in both the Cu and Ni couples.