![]() Al, Ag, and In addition can improve the liquid oxidation behavior at Sn-Zn alloy. Element alloying has been an effective way to improve the antioxidant power of Zn-containing solders. Being very active, Zn will worsen the oxidation performance of solder alloy during and after soldering. About 0.5 wt.% Zn addition to Sn-Ag-Cu-Ce solder alloy can restrain the growth of tin whiskers and strengthen the solder joints. It is reported that minor Zn doped in Pb-free solders can obviously inhibit the growth of intermetallic compounds (IMCs), restrain the growth of Cu 3Sn, and suppress the formation of Kirkendall voids during isothermal aging. Īmong the alloying elements, Zn, Al, and P are very cheap and useful. As for the microstructure instability at soldering, temperature can be suppressed by incorporating fine dispersoid particles into Sn-Bi alloy. Actually, decreasing Bi-content has been an effective way to adjust the thermal conductivity and melting range. īut there are still two issues preventing further application of Sn-Bi alloy, that is, lower thermal conductivity and microstructure coarsening with a serious Bi segregation along the interface, which can greatly decrease the reliability of the solder joint. It can also reduce the damage arising from the mismatch of thermal expansion among various components in electronic assembly. Accordingly, Sn-Bi alloy, represented by eutectic Sn-58Bi, has been used for thermal module connection in notebook ascribed to the low cost, superior wettability, and almost void-free bonding. Sn-Ag-Cu system, notably, Sn-3.0Ag-0.5Cu, has been becoming the main stream in surface mount technology (SMT) as a middle-temperature Pb-free solder. Introductionĭue to the step-soldering process in electronic package, solder alloys joining at different temperature ranges have been in demand during manufacturing procedure. Therefore, the Al/P addition changed their stoichiometry such as the ratio of O/M near film surface. From the half quantitative analysis result, the aluminum had a surface enrichment behavior in liquid solder, so did phosphorus and zinc. Layers near the free surface of oxidation film mostly contained Zn 2+ and Al 3+ oxides for SBZA. Adding trace amount of Al/P to SBZ alloys (SBZA/ABZP) decreased the ratio of O/M (M could be Sn, Bi, and Al/P) and changed the film compositions. The results showed that the oxidation film on SBZ surface was in high concentration of both oxygen and zinc. X-ray photoelectron spectroscopy (XPS) was used to study the properties of liquid oxidation of Sn-Bi-Zn (SBZ) solder alloys and the effect of Al/P on the oxide film. ![]()
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