Simplified Measuring Method of Copper Concentration in Solder Bath Utilizing Copper Dissolution

In lead-free soldering on printed circuit boards (PCBs), the dissolution and disappearance of PCB copper electrodes in solder bath has been a problem for the dip soldering method, such as wave soldering, in which PCBs are dipped in molten solder. In the former report, it has been estimated the influence of solder composition, temperature, and flowing velocity on the dissolution of copper electrodes by the experiment of the dip soldering process and clarified the dissolution rate for Sn-3.0Ag-xCu alloys, which is defined by solder temperature and copper concentration. Based on above study, the simplified measuring method of copper concentration in the solder bath has been developed, which uses the dissolution of wedge-shaped copper pattern formed on FR-4 PCB. As a result of the experiment on dipping the PCB in solder of Sn-3.0Ag-xCu (x = 0.5, 0.9, 1.2 and 1.5) alloys, it has been confirmed that the method enables the measuring copper concentration in the solder bath easily.