SMT & Inspection | July 18, 2005
IPC released lead free solder paste guide
Institute of Printed Circuits, IPC, has released a guide on it's website, with test- and analyze results of lead free solder pastes.
Do you want to know which lead free solder is recommended for our industry? Over the past three years, The IPC Solder Products Value Council (SPVC) invested the equivalent of one million dollars in volunteer time, equipment and supplies to come up with the answer. The SPVC analyzed three key lead free alloys: 96.5/3.0/0.5 tin/silver/copper; 95.5/3.8/0.7 tin/silver/copper; and 95.5/4.0/0.5 tin/silver/copper and the end result of the research is found in this report. The report is a 50 page analysis and recommendation of a lead free alloy. It also includes 18 appendices with nearly 60 megabytes of data and research charts. Some appendices are formatted in Excel to ease further analysis and data manipulation. The testing in the report and appendices includes DSC melt analysis; wetting balance; area of spread; visual inspection of solder joints; X-ray analysis of solder joint voids; temperature cycling testing; thermal shock testing and metallurgical cross section. This data supports the Council's recommendation of 96.5/3.0/0.5 tin/silver/copper (SAC305) as the alloy of choice for lead free applications. The testing program was not intended to compare the lead free alloys' performance against tin lead. However, because tin lead was used as a control, the study does provide some comparisons between the tin lead and lead free alloy performance.