Ultrasonic soldering, mechanical properties of solder joints

Mechanical properties of solder joints have influence on reliability of electronic products. Therefore the knowledge of the mechanical behavior of solder joints is very important. This article deals with comparison of mechanical properties of solder joints prepared with conventional soldering methods and ultrasonic soldering methods. Material for samples preparation was based on two PCB (material FR4) with soldering pads which were soldered together. As solder alloy was used Sn965Ag3Cu0.5 for convention soldering method and active soldering alloy for ultrasound soldering. The mechanical resistance, changes according to used surface finishes the highest share strength, have been achieved for solder joints which ware prepared by ultrasonic soldering on pads with copper surface finish, worst results were achieved for pads with ENIG and HASL surface finishes.