Development and characterization of Sn99Ag0.3Cu0.7-(ZrO2/CuO/TiO2) nano-composite solder alloys

In the present study, the effect of three oxide ceramics (TiO2, ZrO2, and CuO) as reinforcements in 0.25wt% weight fraction was investigated on the quality and reliability of the composite SAC0307 solder alloy.Three types of NPs were applied: TiO2, ZrO2, and CuO. They were mixed into Sn99Ag0.3Cu0.7 (SAC0307) solder paste in 0.25wt%. The primary particle sizes of the NPs were the following: 21nm - TiO2, <100nm ZrO2, and <50nm CuO.Spread tests were applied to study the wetting properties of the solder alloys. A test surface with 50x50mm area was prepared on FR4 substrates with Cu wiring and with imm-Ag surface finishing. The deposits had 5mm diameter and 125 µm thickness. The solder deposits were reflowed in a vapor phase soldering (VPS) oven. The spreading of the solder was measured by an optical microscope (Olympus BX50). Solder joints were fabricated by standard SMT on one-layer FR4 PCBs with Cu wiring. A DAGE 2400 shear tester was used to measure the shear force of the solder joints. The solder joints were loaded with a 3000 hours long 85ºC/85RH% thermal-humidity (TH) test to investigate their corrosion resistance and Sn whisker growth susceptibility. The solder joints were checked in each 1000 hours by a Thermo Scientific Quattro environmental scanning electron microscope (ESEM). Elemental compositions were investigated by a Bruker Energy Dispersive X-ray spectroscopy (EDS).The results showed that NPs slightly decreased the wettability of nano-composite solder alloys. The shear strength of the composite joints generally increased, which proved that the second phase dispersion strengthening mechanism worked. However, the NPs have different effects on the corrosion resistance of the composite alloys. A former study proved that TiO2 could increase corrosion resistance. Now it was observed that ZrO2 did not change it, and CuO decreased it considerably. In correlation with corrosion resistance, the different composite alloys produced different amounts of Sn whiskers during the corrosive climate test.The dataset consists of supplementary SEM micrographs of the cross-sectioned solder joints.