Lead Free Solder Joints Reliability and Process Control
Author: Freddie Chan Company: KIC International Sales, Inc. Date Published: 4/22/2007
Abstract: The interconnection process in PCBA is very much a thermal management process. The thermal exposure, depending on the nature of materials selection, PCBA designs, and the soldering process can at times degrade or even damage the solder joint. The risk associated with the thermal exposures must be carefully studied in order to minimize such risk. With Pb being removed from the solder, component terminations, and PCB solder land finishes, both the process and reliability characteristics has change significantly. Besides influence from the change in materials, the principles in design and process remain very much the same as SnPb system, but due to the behaviors of the new materials that replace SnPb is not as tolerant, works in PCBA design, manufacturing process, equipment selection and maintenance etc. demand to be more extensive than ever.
The large variety of Pb-Free materials posts difficulties in process and reliability studies. It is not possible and not the intention of this article to share information of reliability of a particular system (combination of solder, SMD terminations and PCB finishes), but the approach of getting down to ensure good reliability, as well as some important findings in Pb-Free reliability will be shared with the readers.