Soldering - Lead-free Electronic Soldering

Lead-free Electronic Soldering

More recently environmental legislation has specifically targeted the wide use of lead in the electronics industry. The RoHS directives in Europe required many new electronic circuit boards to be lead free by 1 July 2006, mostly in the consumer goods industry, but in some others as well. In Japan lead was phased out prior to legislation by manufacturers due to the additional expense in recycling products containing lead. However, even without the presence of lead, soldering can release fumes that are harmful and/or toxic to humans. It is highly recommended to use a device that can remove the fumes from the work area either by ventilating outside or filtering the air.

It is a common misconception that lead free soldering requires higher soldering temperatures than lead/tin solder; the wetting temperature in lead/tin solder is higher than the melting point and is the controlling factor - Wave soldering can proceed at the same temperature as previous lead/tin soldering. Nevertheless many new technical challenges have arisen with this endeavor; to reduce the melting point of tin based solder alloys various new alloys have had to be researched, with additives of copper, silver, bismuth as typical minor additives to reduce melting point and control other properties, additionally tin is a more corrosive metal, and can eventually lead to the failure of solder baths etc.

Lead-free construction has also extended to components, pins, and connectors. Most of these pins used copper frames, and either lead, tin, gold or other finishes. Tin finishes are the most popular of lead-free finishes. Nevertheless, this brings up the issue of how to deal with tin whiskers. The current movement brings the electronics industry back to the problems solved in the 1960s by adding lead. JEDEC has created a classification system to help lead-free electronic manufacturers decide what provisions to take against whiskers, depending upon their application.