2 Solder-ball forming during stamp soldering Solder ball forming is a phenomenon caused by many factors and manifested in small solder alloy balls around the solder jointThe possible causes are improper fluxing or preheat profile, wetting problems because of surface contaminations, solder mask defects, escaping gases from the PCB laminate
3 Solder-ball forming during stamp soldering The concerned PCB-s showed uneven PTH plating surface which can be a root cause of blow holesProblems occured with immersion tin and also with HASL plated PTH barrels.Although the surface of the HASL was satisfactory, the underlying copper plating was uneven and critical thin.
4 Solder-ball forming during stamp soldering The mechanism of solder ball forming is in correlation with the escaping gases from the PCB laminate resin, caused by the higher temperatures and contact times used in lead free technologyThe higher copper dissolution rate of the lead free solder alloy aggravates the problem, the critical thin copper plating can completely dissolve which results free out gassing from the PCB laminate.
5 Solder-ball forming during stamp soldering The proposed actions are primarily to eliminate te root cause, which means strict quality control over the PCB supplier’s products. Lead free soldering is more sensitive of PCB quality.The yield can be improved by heat treating of the PC boards, thus removing volatile materials from the laminate.
6 Manufacturing and process regulations for EL13 The task was to collect the related documents; regulations, datasheets, heat profiles etc. for each production phases and organize them to a html coded tableTo collect the required documents, the concerned engineers has been contacted and the database of Salzgitter has been examined