Adhesive joining or lead-free soldering?

Low-cost tin-lead solders have been used as interconnecting and surface coating materials in electronics for many decades. These alloys have good electrical and mechanical properties, reasonably low melting point, and good reliability, but they are not nature-friendly. As a result of an effort to eliminate the use of lead-containing solders there have been started different regulation and legislation activities in many countries. Some of them are presented in this paper. There are two basic ways of no-lead replacement: lead-free solders and electrically conductive adhesives. Basic types of lead-free solders and electrically conductive adhesives are presented, Selected methods for testing of quality of soldered and adhesive joints are mentioned, and results of measurements of selected types of lead free solders and conductive adhesives are mentioned, too. It has been found that quality of soldered joints is higher than quality of adhesive ones.