A comparison of the quality of lead-free solder pastes

The European Commission has decided that from the second half of 2006 only lead-free solder pastes will be permitted for use in the electronics industry. Earlier results of testing showed that lead-free solder pastes may not be appropriate for both printed-circuit-board (PCB) and hybrid-circuit applications, because of the materials' compatibility with the soldering process and with the solder pads. The basic properties of the investigated pastes show which of the tested solder pastes can be used for both applications. After selection of the appropriate solder pastes, reliability tests were conducted. The surface insulation resistance was tested for both the hybrid circuits and PCBs, whereas the mechanical strength of the soldered joints of components was only tested for the PCBs.