Some Problems in Switching to Lead‐free Solders*

The electronics industry seems to be under slightly less pressure, at present, to move to lead‐free solders. Nevertheless, many companies are interested in switching to comply with initiatives aimed at reducing the use of toxic materials such as lead. At the same time, these and other companies are hoping to use the improved properties of many lead‐free solders to increase solder joint reliability. While lead‐free solders can indeed give improved properties in the proper system, using them with lead‐containing materials can actually give poorer properties and uncertain reliability. It is important to understand these materials' interactions as thoroughly as possible before introducing new solder compositions. To illustrate this point, some case histories will be presented, along with a general discussion of how solders and substrates can and do interact.