RoHS PCB Explained

RoHS Introduction

Recently several PC hardware pieces were launched as “RoHS PCB Compliant” and you should see more and more RoHS-compliant products reaching the market on the next months. In this tutorial we will explain what RoHS is and what is its impact to the computer industry.
RoHS stands for Restriction of Certain Hazardous Substances. It is an European legislation that bans six hazardous substances from manufacturing processes: cadmium (Cd), mercury (Hg), hexavalent chromium (Cr (VI)), polybrominated biphenyls (PBBs), polybrominated diphenyl ethers (PBDEs) and lead (Pb).
RoHS is also known as “lead-free” but this law deals with other five substances as well.
This legislation is effective July 1st, 2006 and from this date on products using these substances cannot be sold in Europe anymore. Together with RoHS, another directive dealing with the recycling of electrical and electronic equipment, called WEEE (Waste from Electrical and Electronic Equipment), will take place.
Because of RoHS, manufacturers of electronic equipment will have to rush to deliver lead-free equipments in order to be able to sell their products in Europe.

RoHS PCB

The problem is that solder traditionally uses 60% of tin (Sn) and 40% of lead (Pb) and manufacturers will have to research other materials to make solder. As you know, solder is what “glues” all the electronic components on the printed circuit board (PCB) of an electronic product. The most common replacements for lead are silver, copper and bismuth.
These alternative materials, however, bring several challenges:

• Higher melting temperature: traditional tin/lead solder melts at 180° C (356° F) while lead-free solder melts at 227°C (441°F). This means that the electronic components must be able to support this new soldering temperature in order to allow lead-free solder to be used.
• Still under development: tin/lead solder is used for ages and the soldering process using this alloy is very well known. Lead-free solder is still a child and a lot of research and development is still going on with several different materials. So far there is no industry standard for lead-free solder.
• Repair: when repairing electronic equipment, the solder used should also be lead-free. The repair technician should know exactly what kind of solder was used when the equipment was manufactured. Usually this is marked on the printed circuit board (PCB) of the equipment, but this information may not be available. But it is safe to use 99C alloy (99.7% tin, 0.3% copper) when repairing lead-free equipments.
• Visual inspection: lead-free solder joints look a lot different to traditional tin/lead joints and an untrained eye can assume that the joint is faulty.

Of course besides the solder all other pieces of the electronic equipment – like components and the printed circuit board (PCB) – should have none of the six banned materials to be considered RoHS-compliant and allowed to be sold in Europe.

Why Lead?

The whole problem is basically with the electronic waste. A lot of electronic equipments are ending their lives in open junkyards and waste dumps all around the world – many of them with no chemicals control. The water from acid rain dissolves lead and other hazardous materials from electronic equipment, and the rainwater mixed with these materials go straight to the water table and then to the drinking water.
Lead can affect almost every organ and system in the body, especially the central nervous system. Kidneys and the reproductive system are also affected. The effects are the same, whether it is breathed or swallowed. At high levels, lead may decrease reaction time, cause weakness in fingers, wrists, or ankles, and possibly affect the memory. Lead may also cause anemia.
It is interesting to note that although the electronics industry has been directly targeted for lead removal by the European law, only a small proportion of lead is actually used in electronic equipment production: only 0.49% of all manufactured lead is used in solder and only 2% of the manufactured lead is used in all electro-electronic industry. Battery manufacturing, for example, consumes 80% of the manufactured lead.

And How About the USA?

Even though the United States have no legislation similar to RoHS or WEEE, the state of California passed a law prohibiting the sale of any electronic product that would be prohibited from sale in Europe because of the presence of heavy metals. This law, which is being called “California RoHS”, was effective September 2003, with a compliance deadline of January 2007.