| dc.description.abstract | The melting point of the eutectic Sn-58Bi solder at 138°C, is desirable for advanced electronic packaging; however, the high hardness and brittleness of this alloy can lead to the damage of devices during processes and cause a reliability issue. In this study, a hybrid solder containing Sn0.3Ag0.7Cu (SAC0307) and Sn-56.8Bi-1Ag-0.2Cu (SnBi) is introduced to improve the mechanical properties, and the SAC solder can be used as a buffer layer for absorbing external stress. Printed circuit boards (PCBs) are packaged with Sn56.8Bi1Ag0.2Cu and SnBi/SAC0307 (hybrid solder) by surface mount technology (SMT) under different reflow temperatures. Further, an aging test was conducted under 75°C, 100°C, and 125°C for 5, 10, and 20 days, respectively, and interface reactions and surface morphology are then investigated. Furthermore, an image analysis software is introduced to calculate the thickness of intermetallic compounds (IMC), and the activation formation energy can, therefore, be calculated by kinetics. The difference of the shear strength among varying sizes (0402, 0603, and 0805) of the chip component was compared by shear tests. The microstructure of different fracture modes and the fracture surface are observed, and the results are summarized. Results show that the thickness of the IMC increased linearly with the increase of aging time and temperature. Shear test results reveal that SnBi shows high possibility of brittle fracture, whereas the SnBi/SAC0307 hybrid solder represents a tendency of ductile fracture in the size of 0603 and 0402. To summarize, the hybrid solder indeed inhibits a brittle fracture, and the mechanical properties of joints is improved. | en_US |