Soldering considerations for lead-free printed circuit board assembly - an Envirowise Guide

摘要

Purpose - To give an overview of the issues encountered, and changes that need to be made in the various types of soldering process when converting them from conventional to lead-free assembly. Design/methodology/approach - This paper has been written to provide a review of the lead-free reflow, wave and hand soldering processes. Problem areas highlighted and methods for adjusting and optimising each type of soldering process for compatibility with lead-free solders are described. Findings - The move to lead-free soldering in electronics assembly can lead to a number of issues that affect process performance, yields and reliability. Problems that are sometimes encountered with conventional lead-bearing solders can exacerbated when moving to lead-free. Many of the issues are associated with the higher melting points of the recommended lead-free solders. Fortunately, these issues are now well known and, with care and attention to process optimisation, they can largely be avoided. Originality/value - The value of the paper lies in its ability to provide information on the types of problems and issues encountered when moving to lead-free solders and the advice it gives on how to avoid them. It also describes how to convert the various lead-free soldering processes used in PCB assembly using a range of measures that can minimise defects, avoid common problems and optimise yields. Sources of additional assistance are also identified.