Has lead-free made the industry any greener?

Despite the advent of RoHS in July 2006, electronics is essentially a ‘green’ industry. It provides more functions and services but uses less energy and fewer materials.

To illustrate this point, the author compares the motor industry with electronics. In 1947, a Holden car would travel about 160 km in about three hours and use about 11 litres of petrol. Today, a diesel Cruze can make the same trip on better roads in about two hours using less than five litres of fuel.

Compare this with electronics. In 1947, the Eniac computer had some 19,000 valves and perhaps a kilobit of memory and needed 200 kW - enough to supply hundreds of homes. Today, he says, a notebook computer contains some 2.5 billion transistors and 4 GB of memory making it 100,000 to a million times more powerful and at a power consumption of around one thousandth of that needed for the Eniac.

In terms of efficiency, the notebook produces about a billion times more calculations per watt.

Says Lasky:

“In 65 years, the motor vehicle has delivered incrementally more functions per energy used while the computer and, by association, electronics, have delivered exponentially more functions per energy or materials used.”

For this reason, he claims that electronics is a very ‘green’ technology but it assumes that ‘green’ means electronics is delivering more and more functions while using less and less ‘stuff’. This raises the question of what about the materials used in electronics and has RoHS made the industry ‘greener’?

When RoHS was brought in, it banned a variety of materials including mercury, hexavalent chromium, lead, cadmium and two flame-retardant chemicals: polybrominated biphenyls (PBB) and polybrominated diphenyl ether (PBDE). RoHS, in conjunction with the recycling directive WEEE, is designed to make the European Union a safer environment. However:

“I know of no study or analysis that supports this RoHS hope. If enforced, WEEE does improve ‘greeness’ as about 85% of products must be recycled,” he says.

At the same time, electronics that aren’t recycled finish up as landfill, where they can still pollute but the directive does make recycling safer for recyclers. The green mantra of RoHS has the three pillars of recycle, reduce and re-use.

“Many still argue that non-RoHS compliant products could and have been safely recycled with proper precautions so why put the electronics world through the pain of RoHS? I find this argument compelling.”

The answer to this question is to ask another question: does RoHS help anyone else? It is estimated that some 50 to 80% of waste electronics is sent to third-world countries where it is illegally recycled. In some cases a man removing solder from circuit boards might later use the same container to cook his dinner.

Lasky says that in the Chinese city of Guiyu, individuals not only work with toxic materials but the whole town is contaminated. In the future, the use of RoHS-compliant products should make life safer for such people.

Its energy efficiency, increased functions and miniaturisation make electronics a green industry, yet it is claimed that because more tin and solder are used in lead-free solders, the environment is being made worse. The argument is that the increased demand for these metals generates mining pollution and has forced prices of them to new heights.

In addition, the higher melting temperatures needed for lead-free soldering demand more electricity.

Here are a few facts about soldering. Some 90,000 tonnes of solder are used in electronics with about 80,000 tonnes absorbed by wave soldering and 10,000 tonnes taken up by SMT. However, electronics soldering is a subset of all soldering that includes alloys for brazing pipes and takes up some 190,000 tonnes of tin, and solder is the largest tin user as it is the base material for almost all solders.

Using tin/lead solder, about 57,000 tonnes of tin (90,000 x 63% tin) would be consumed annually with lead-free solder about 88,000 tonnes (90,000 x 98% tin). Looked at quickly, this seems like an annual 30,000 MT of tin used. But lead-free solder is some 14% lighter without lead and wave soldering uses nearly 90% of the solder used in electronics. Solder used here is measured by volume, not by weight.

However, it might be best to just look at tin use. The US Geological Survey reveals that about 300,000 tonnes of tin are consumed annually but it seems that the increase is more likely due to the economy rather than RoHS.

As far as silver is concerned, there is little or none used in most solder alloys. Only about 3% of the 10,000 tonnes of SMT solder or 300 MT of solder are used in electronics or about 1.5% of the 22,000 MT produced annually.

“Electronics solder use since RoHS has not caused tin use to increase nor is it a significant factor in solder use,” says Lasky.

While the obvious disadvantage of needing higher temperatures in reflow ovens is a by-product of RoHS, is the increased electricity use significant? That answer is no.

The melting point of lead-free solder is 225°C and tin/lead is 183°C. Using US figures, the author estimates that a typical SMT oven uses $7000 worth of electricity a year at $0.072 kWh or about 100,000 kW.

Based on an extrapolation of figures from an earlier study, Lasky estimates that there are some 50,000 SMT lines in the world using about 5 x 10⁹ kWh (50,000 ovens x 100,000 kWh).

He goes on to explain that:

“An oven processing tin/lead solder would run at 210°C versus a lead-free oven at 250°C. The added energy use would be about 22% more. If all the assembly lines in the world were SMT, the added energy use would be about 0.22 x 5 x 10⁹ kWh = 1 x 10⁹ kWh. The cost would be about $100 million at $0.10 a kWh to an industry that generates some $1.5 trillion in sales.

The added cost runs out at 0.0067% of sales and since world electrical use is around 150,000 x 10⁹ kWh per year, the increase is some 1/150,000th of all electrical use or 0.00067%.

He sums this up by saying that although more electricity is used, it is not significant when measured against either the value of electronics sold or the global use of electricity.

Lasky comes to three conclusions:

• Electronics is a ‘green’ industry because it uses fewer materials and less energy while providing more functions;
• RoHS will have an “overwhelming positive effect” on the developing countries that are using unsafe recycling techniques;
• There is little evidence to show that more tin, solder or electricity are being used as a result of lead-free soldering.

This article is based on a paper written by Dr Ronald C Lasky of the Indium Corp in the US.

By Mike Smyth