Reliability of solar cell´s solder joints

This work is about interconnection of the solar cell and the substrate. Ceramic substrate and back side contact solar cells were used. There are 36 solar cells which were contacted on 12 substrates. The Ag paste was used as a conductive layer and lead free solder paste was chosen as a solder. 3 firing profiles in 4-zone furnace were tested. The thermal cycling is the next step. 6 substrates will be tested with 1000 cycles and 6 substrates will be tested with 3000 cycles. The cycle is in the range -40degC to 125degC, ramp 10degC/min, dwell 10 min, period 60 min. This is the common test cycle regime used in military applications testing, hence the wide temperature range of the cycle.