Evaluation of soldering processes for high efficiency solar cells

Solar cells have to be connected electrically to each other in a solar module. During the last years, new connection techniques with low stress have been developed, such as selective soldering. The industrially most frequently used selective soldering techniques are induction soldering, contact soldering, laser soldering and spot light soldering. The aim of this work is to evaluate the characteristics of solder joints, which are produced by the use of selective soldering techniques. Therefore adhesive strength tests, electrical characterizations and x-ray analyses have been performed. In this process one front-side metallization, a SnAg-solder and a SnPbAg-solder were used. The characterization method will be demonstrated on the spot light soldering technique. In addition the influence of the solder joint quality on the resistance of the whole solar cell will be demonstrated and discussed.