TWI Industrial Member Report Summary 732/2001
Solder alloy is the primary joining material used by electronic assemblers to attach components to circuit boards. Of the alloys used, tin/lead compositions are by far the most common, and the assembly industry has developed through the last century with these compositions undergoing very little change. These materials are technically proven through the build-up of historical data and are available commercially in several forms to assist with electronics production. However, they are now being challenged by non-lead containing alloys, a challenge driven by two central causes. The first is draft EC legislation (WEEE, waste electrical and electronic equipment) which targets for restriction the use of lead in electronic equipment, and the second is the marketing advantage perceived by some equipment makers that supplying a product free of lead will position them as 'environmentally friendly' and thus lead to greater market share.
Several technical issues are raised when lead-free solders are used in place of tin/lead alloys. At present, there are no drop-in replacement products in terms of processing or joint features. Focusing on solder paste, this report highlights some of the technical differences seen when lead-free solder pastes are used in assembly. It compares several commercially available materials and assesses their performance with respect to tin/lead paste.
- Develop a TWI standard test board for electronics soldering
- Establish the reflow performance of four commercially lead-free solder pastes using the test board
- Evaluate the joint features exhibited when the above pastes are used to solder standard devices