Fatigue life analysis of Sn96.5Ag3.0Cu0.5 solder thermal interface material of a chip-heat sink assembly in microelectronic applications

Abstract

The reliability of microelectronic devices during operation has been a major challenge in recent years. Microelectronics devices will fail if one or more components do not function properly. Thermal interface materials are more likely to fail because of the role they play in heat management. Lead free solders such as SAC305 solder (Sn96.5Ag3.0Cu0.5) have become the thermal materials of interest because of their high thermal conductivity and government legislations on the ban of lead. Ansys finite element software was used for the design and analysis of the microelectronic device studied. The bond line thicknesses of the SAC305 solder thermal interface material were varied from 0.035 mm to 0.175 mm and a thermal load was applied using commercial thermal cycle profile of −40°C to 80°C. The results obtained showed that stresses and strains reduce as the lead free solder thickness increases. The number of cycles to failure and plastic work density increased as the SAC305 solder thickness is increased. This research showed that an increase in SAC305 solder thickness will improve thermal conduction and reliability. However, the solder thickness is limited to the gap between the chip-heat sink surfaces in contact.