HISOLD 4P Q&R, COST project for solder material innovations and solder joint properties assessment

The solder joints properties are in connection with their microstructure, which is the result of the soldering process temperature gradient action over the trinomial solder alloy/paste, electronic components terminals/pin and PCBs pads characteristics (4P soldering model). The temperature gradient was determinated by the specific thermal profile of the soldering process. As part of COST Action MP0602, Working Group 2 (The properties of solder joints), the HISOLD 4P-Q&R group project investigated, into integrated approach, the properties of solder joints realized by different paste-pad-pin-process reflow soldering formulas, with focus on innovative lead-free solder alloys, including composite type with nanoparticles content. The 4P soldering model concept and the project proposed investigations are based on numerous experiments and macro/microstructural analyzes including optical and X-ray inspections, surface acoustic microscopy (SAM), scanning electron microscopy (SEM), nanoindentation and electron backscattering diffraction (EBSD), before and after electrical, mechanical and climatic tests. Proposals for solder joints functionality standard test methods, test vehicles and data bases was elaborated as result of environmental stress studies, thermodynamical, rheological and macro/microstructural solder joints analyses, based on IPC references. A standard SAC solder alloy and the reflow soldering process was used as reference. As a consequence, the DFM concept can be improved with practical manufacturing requirements.