The intermetallic compounds formed after reflow and burn-in testing of a Sn-20In-0.8Cu solder ball grid array (BGA) package are investigated. Along with the formation of the Cu 6 (Sn 0.78 In 0.22 ) 5 precipitates (IM1) in the solder matrix, scallop-shaped intermetallic compounds (IM2) with a compositional mixture of Cu 6 (Sn 0.87 In 0.13 ) 5 and Ni 3 (Sn 0.87 In 0.13 ) 4 appear at the interfaces between the solder balls and Au/Ni/Cu pads. A significant number of intermetallic particles (IM3), with a composition of (Au 0.80 Cu 0.20 )(In 0.33 Sn 0.67 ) 2 , can also be found in the solder matrix. After aging at 115°C for 750 h, an additional intermetallic compound layer (IM4) with a composition of (Ni 0.91 Cu 0.09 ) 3 (Sn 0.77 In 0.23 ) 2 is formed at the interface between IM2 and the Ni layer. The ball shear strength of the Sn-20In-0.8Cu BGA solder after reflow is 4.5 N and will rise to maximum values after aging at 75°C and 115°C for 100 h. With a further increase of the aging time at both temperatures, the joint strengths exhibit a tendency to decline linearly at about 1.7×10 −3 N/h.

Indium tin oxide (ITO) ceramics are bonded with ITO and Cu at 250 °C in air using an active solder Sn3.5Ag4Ti(Ce, Ga). The mechanism for such low temperature soldering of ITO ceramics in air has been investigated. Electron probe microanalyzer (EPMA) analyses reveal that the element oxygen distributes uniformly within the solder matrix after soldering, while Ti segregates effectively at the ITO/solder and Cu/solder interfaces at such a low temperature, giving satisfactory joining results of Cu/Cu, ITO/ITO, and ITO/Cu in air.

Abstract The morphology and growth kinetics of the intermetallic compound formed during the reaction between liquid Sn-20In-2.8Ag solder and Ag substrate are studied in the temperature range 225–325 °C. The results indicate that the intermetallic compound Ag2+x (In, Sn) of scallop shape appears at the interface. The intermetallic thickness versus reaction time shows a parabolic relation, indicating that the growth of this intermetallic is diffusion-controlled. The activation energy calculated from the Arrhenius plot of the intermetallic growth rate is 41.6 kJ/mol. By marking the original interface with a Ta thin film, the dissolution of Ag into solder and the growth mechanism of the intermetallic compound have been clarified.

For the development of a low-melting-point filler metal for brazing aluminum alloys, a series of Al–Si–Cu–Zn alloys has been studied. Through differential thermal analysis (DTA) analysis, the melting temperatures of such Al–Si–Cu–Zn filler metals were determined. The results show that the addition of 10–30 wt.% copper into the traditional Al–12 wt.% Si filler metal causes its solidus temperature to decrease by about 60 °C. An addition of 10–30 wt.% zinc into such Al–Si–Cu ternary alloys will cause their solidus temperatures to drop further to a value lower than 500 °C. Metallographic observations indicate that the addition of zinc into the Al–Si–Cu alloys inhibits the formation of the Al–Si, Al–Cu and Al–Si–Cu eutectic phases. The remaining phases are a CuAl2 intermetallic compound, an α-Al solid solution and silicon particles.