Prepare For The Upcoming Electronic Apocalypse

Once or twice before I've written brief posts about something called RoHS, or Restriction of Hazardous Substances, a directive from the European Union to severely restrict six toxic substances used in consumer electronics (lead, cadmium, mercury, hexavalent chrome, PBB, and PBDE – the last two being fire retardants used in plastics). This directive was enacted to reduce the amount of these toxic substances entering the waste stream. The concern of the EU was that with the increasing number of electronic devices being used by the average person, the number of these devices entering the waste stream would be increasing at a like rate as such devices reached the end of their useful service life. A mandatory recycling system was also set up to help keep the amount of electronic and electrical waste going to the landfills to a minimum.

The original target of the directive was items like cell phones, PDA's, computers, MP3 players, and related types of electronics, devices with an expected service life of 2 to 3 years. Then more and more electronic and electrical equipment was added to the list until contained just about every one you can think of. It certainly seemed like a good idea...at the time. But there was a major problem with RoHS directive: the ban on lead.

Lead has been used in electronic solders for as long as there's been electronics. Solder is an alloy made up of tin and lead, the most common type with a ratio of 63% tin and 37% lead. This particular mixture has exceptional electrical and physical properties that make it perfect for use in electronics. Yet due to the EU RoHS directive, it is now banned. The problem?

There isn't an acceptable substitute that has the same properties as tin/lead (SnPb) solder.

But that didn't stop the EU from banning it anyways. And now we'll all pay the price.

Replacing tin-lead with pure tin is turning out to have been a huge mistake. There are two significant differences between lead-free assembly and lead-based assembly.

(1) Lead-free assembly is not better for the environment, it is worse. The additional tin mining required to produce high-purity tin alloys, plus the mining of other precious metals required to alloy with tin in substitution for lead is a poor trade for the use of existing lead, much of which comes from recycled products. This information comes from a study conducted by the U.S. Environmental Protection Agency (EPA). The study undercuts the primary basis for ROHS.

(2) Lead-free assembly is less reliable than lead-based assembly. The E.U. environmental commission admits this point. That's why they grant exceptions for military and high-reliability applications that still use SnPb solder.

One of the big problems with the lead-free solders being used is that they can promote the growth of tiny tin whiskers, thinner than a human hair. In and of itself, this might not be a problem. But what happens if one of those whiskers growing on a component lead causes a short to another component?

The device in which the components are located fails.

If the time it took for something like this was measured in decades, then there really wouldn't be a problem. But what if it only took 2 to 3 years?

Now you're getting it.

If the electronic device is a cell phone, it probably won't matter. But what if it's your relatively new 52” LCD HDTV? Three years after you took it home it suddenly stops working. It's now out of warranty and you'll have to pay for the cost of diagnostics and repair. And then another two or three years down the road it fails again for the same reason. How would you feel? I know I'd be pissed off.

But now let's look at something even more daunting.

What happens if a RoHS-compliant lead-free circuit board ends up in a nuclear power plant and tin whisker growth causes a short circuit, which in turn causes a false alarm that causes the plant to shut down its reactor?

Think it won't happen? Think again.

How about a worse scenario?

That same circuit card has a short caused by a tin whisker that prevents a detected fault that should shut down the reactor is never sent. The reactor that should have been shut down because of a system failure instead stays on line and causes a much bigger problem.

Mind you, consumer electronics and those used to monitor and control nuclear power plants are different, but they could suffer from the same problem.

The lead-free solder problem could also affect transportation. What of the computers that control the power train in your car or truck? Would you like to pay to have them replaced every few years because tin whiskers caused a malfunction? I know I wouldn't. (Thank goodness aviation electronics are exempt, allowing the use of leaded solder.)

Think about all of the appliances in your home requiring replacement of electronics every few years because short sighted bureaucrats and know-nothing politicians decided that they had to save us from ourselves. RoHS has spread to other countries as well, making it mandatory that manufactures build products that meet those requirements if they want to stay in business.

The irony of the whole thing? Lead, as it is used in electronics, has never been a problem in regards to causing toxic pollution in land fills. Because it is alloyed with tin, it doesn't leach into the ground like lead in paints or old car batteries have been known to do. How do I know this?

Because the EPA says so.

Feeling nervous yet?

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