PCB | December 12, 2008

"The RoHS directive should be reconsidered!"

PCB consultant Lars Blomberg believes that the current RoHS directive should be reconsidered. For over 50 years, the PCB’s has been used as carrier and wiring for electronic components. The modest development of PCBs in relation to components and software is remarkable.
PCBs have evolved from single-sided to double-sided hole plated to multi-layer to blind and hidden vias, and sequential structured boards, but the materials have mainly remained the same, i.e. copper as conductor, tin/lead as solder joints and Fr4 as substrates.

If we look more closely at the various materials, it can be seen that copper has excellent electrical as well as thermal properties – it is elastic and has good solderability. The copper is also highly suitable for chemical and electrolytic plating, which makes the metal virtually irreplaceable.

In the case of tin/lead solder joint, it is the same thing. Eutectic SnPb (63/37) has been proven to be the perfect solder joint, because of its elasticity, low soldering temperature and good aging properties.

In the case of FR4 (Flame Retaradant 4) as the carrier material, it has always worked very well together with copper and the soldering parameters for tin/lead. Another advantage is that all manufacturers have produced a similar material, which made it easy to use from multiple suppliers – without having to change the basic data.
What I wish to say is that you skould never change a winning team, but that is exactly what happened when the use of lead for PCB manufacturing had been banned.

The reason that lead is considered to be harmful to the environment – when it is deposited in the nature and leaks out, it builds up in plants and microorganisms and eventually also affects animals and humans alike. So it is perfectly understandable to ban lead in gasoline, but it is very surprising that it was not possible to prohibit lead in ammunition (lead shot), which is more or less made to be ‘deposited’ in nature.

But why is electronic waste predicted to end up in nature and not to be recycled?
It is not difficult to understand how politicians have come to the conclusion of a ban. If you are sitting in Brussels and will take a position on environmental issues and begin to look at something called the Printed Circuit Board - shortened to PCB. You will start by ‘googling’ on PCB and that can intimidate anyone. Americans have been a little smarter and shortened Printed Circuit Board to PWB (Printed Wiring Board). After the first shock, you will find that the printed circuit boards contain copper, tin, lead and glasfiberepoxi with brominated flame retardants, which are not likely to calm down decision-makers.

If we start with copper, this metal has been banned in antifouling paint for boats and is demonstrably very toxic. Try to hammer a copper nail into a tree and it will die; you can treat your lawn with copper sulfate – the soil will be shimmering green, but the grass will be gone. You could then through away your lawn mower, which of course could be seen as an environmental benefit? This applies to both – tin and lead – they are highly toxic if they are released into nature.

In the case of glassfiberepoxi, it is not very environmentalfriendly either; in the manufacturing process or later during waste treatment (burning), when it also contains bromine as flame retardant – this will certainly not make things better. However, it should be noted that the bromine compound, which has been used in Fr4 materials, is TPPBA (tetrabromo bisphenol-A) which has been proven not to be dangerous.

Considering these facts the result – a printed circuit board should be prohibited. This however is politically impossible, so the choice is to ban lead and to allow a variety of exceptions, such as allowing a reduced amount of lead to be negligible.

What is now achieved provides no benefits to the environment – if we do not assume that every single scrapped printed circuit board will be thrown into nature. However, it has seriously affected the electronics industry by rising the soldering temperatuer to a point were it is very close to were components and other materials are decomposing. This in turn will lead to more errors and faster aging and a greater consumption of energy in general. This raises immediately the question – why are the defence and automotive industries exempted from the ban. The answer must be that the risks are realized.

Printed circuit board materials have also gotten to a stage where it is impossible to switch between suppliers, as materials have different properties.

If we continue to solve the problem by banning all toxic material, our civilization will return to a Stone Age society. The more obvious solution would be Recycling. We must ensure that there will be no materials dumped into our environment, but all waste must be taken care of in an environmentally sound manner. For example, tin/lead should be easy to recycle, because of its low melting point.

So I believe, the banning of lead for some electronics described in the RoHS directive should be reconsidered.

Lars Blomberg is working as a consultant in Sweden. He comes with a background of 40 years of experience in the Swedish PCB industry.


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