Papers by Keyword: Growth Rate Constant

Abstract: The effect of Ag content on the morphology of the intermetallic compound (IMC) layer at the interface between Sn-xAg-0.7Cu (x=0.0 wt.%, 0.3 wt.%, 0.8 wt.%, 3.0 wt.%) and Cu substrate has been investigated. After reflow, the slight addition of Ag element can suppress the growth of IMC. However, as the Ag content increases, the thickness of IMC is enhanced. After aging at 150°C, the IMC growth rate constant decreases with the addition of Ag. The IMC growth rate constant of Sn-3.0Ag-0.7Cu is 0.94864×10^-5 μm²/s, which is the lowest among these solders. As the Ag addition is 0.8wt% and 3.0wt%, the Cu₃Sn growth rate constant is 0.16641×10^-5 μm²/s and 0.18496×10^-5μm²/s, compared to the Sn-0.7Cu solder decreased 54% and 49%, respectively. As a result, the addition of Ag element improves the anti-aging properties and suppresses the growth of Cu₃Sn layer, which leads to the improvement of solder joint reliability.

Abstract: Reaction diffusion in liquid Pb free solder- and solid Pb free solder- pure Cu systems has been investigated in the temperature range between 397 K and 563 K. The Pb free solder of which composition is 95.7 mass% Sn, 2.8 mass% Ag, 1.0 mass% Bi and 0.5 mass% Cu and 99.99 mass% oxygen free Cu has been used. In the liquid Pb free solder-pure Cu system, as soon as the solder melted down, an intermetallic compound phase formed preferentially, and grew with increasing diffusion time. Only the phase exists in the experimental time up to 120 seconds. The layer thickness of the phase obeyed the parabolic law. On the other hand, in the solid Pb free solder-pure Cu system two intermetallic compounds  phase and ’ phase form and grew with increasing diffusion time, although the  phase forms after an incubation time at low temperature. The layer thickness of these intermetallic compounds obeyed the parabolic law. The growth rate of ’ phase is greater than that of the  phase. The growth kinetics of the intermetallic compounds and the diffusion behavior in the ’ phase have been investigated.