Reliability of Embedded SMD Resistors Realized by Face–down Technology

This paper is focused on quality of solder joints. Solder joint were realized on the surface of the substrate as well as embedded into the substrate. Two types of substrate materials (low Tg and high Tg) were used for this research. The objective of this research was determining the realistic lifetime of embedded solder joints. This lifetime was determined by comparison of embedded solder joints with standard solder joints on the surface of the substrate. Lifetime of the samples was evaluated by thermal cycling test between 125°C and -45°C. 1000 thermal cycles were performed. Electrical properties of the samples were measured by 4-point probe method. Microstructure of the cross-sections of the tested samples were analyzed as well.