A Sligo IT researcher is studying an environmentally friendly solder that will take the harmful lead out of electronics, writes Gráinne Black
It's time for us to get the lead out, according to research student Shane O'Neill from the Department of Mechanical and Electrical Engineering in the Sligo Institute of Technology.Lead ranks among the top hazardous substances and is known to be detrimental to health. Yet it is heavily used in the electrical and electronics industries, with knock-on consequences for their eventual disposal.
Up to 40 per cent of the lead found in landfill sites comes from waste electrical and electronic equipment, according to O'Neill. This same waste lead poses dangers to the health of recycling workers and to the environment where it is stored prior to recycling.
This situation will soon change however due to the introduction last year of new EU regulations. The use of lead in the manufacture of such equipment, including household appliances, computers and toys, will be banned from July 2006 under the new controls. The race is therefore on to find alternative materials that are lead-free and environmentally friendly.
Every year, 65,000 tonnes of lead are used worldwide in the making of solder alone. The solder, an alloy of lead and tin, is used to form the connections between electrical and electronic components and the circuit boards on which they are mounted.
O'Neill has been studying an alternative solder consisting of a mixture of tin, silver and copper to see what the optimum conditions are for its use in industry. The old lead solder "has been used for 50 years and it is reliable", he says but the new type must be tested to optimise the conditions under which it might be used.
His research has focused on two soldering processes known as paste printing and reflow. The former involves printing solder paste onto the circuit board, and the latter involves gradually heating the solder to a temperature above its melting point and then cooling it to make the electrical and mechanical connections.
The aim of O'Neill's work is to "develop a template for industry" when using this type of lead-free solder. He carried out the processes under different conditions and statistically ranked them to determine which method was the most efficient.
"The results have been good," he says, given that the optimum handling conditions for the leaded and lead-free solder are similar. The more similar the two are, the fewer adjustments that must be made to the current industrial set up.
However, the melting point of the lead-free solder is higher than that of the traditional solder. This means that the temperature at which the reflow process is carried out must also be higher. "This has knock-on effects," says O'Neill, principally whether the electronic and electrical components can survive a hotter soldering process.
There is also the danger of the "popcorn effect", he says. This can occur where a small amount of moisture trapped in a component vaporises as it is heated, blowing the top off the part. Because of the higher temperatures used for the lead-free solder, there is an increased risk of the popcorn effect, O'Neill explains.
Despite this, the future of tin, silver, copper solder looks bright. Not only is this type of solder environmentally friendly and in line with EU legislation, it also has advantages for industry, O'Neill believes. "Consumers are inclined to purchase products that are perceived to be environmentally friendly," he says. And despite the fact the lead-free alternative contains silver, for reflow soldering the cost of the lead-free solder is no higher than that of the traditional kind.