April 2012
« Mar   May »



RoHS and Electronics Reliability

ROHS stands for Restriction of Hazardous Substances Directive. It is a mainly European effort to reduce lead (Pb), Mercury (Hg), Cadmium (Cd), Hexavalent Chromium (Cr+6), Polybrominated Biphenyl (PBB), Polybrominated diphenyl ethers (PBDE) and Acrylamide in electronics and consumer goods.

The main effort appears to be in the reduction of lead in circuit boards and solder.  Generally speaking, reduction of pollutants is a good thing.  Lead is a toxic, especially to young children. Mercury is a potent neurotoxin.  Those other elements and chemicals don’t sound good either.

There are all sorts of green logos and other nice looking things attached to products which meet the standard.

Typical ROHS label

Typical ROHS label

I feel better, don’t you?

Now for the other side of ROHS.  According to Lead Free Electronics Reliability (large .pdf) by Dr. Andrew Kostic, the effort had been hugely expensive with very limited results:

A huge (~ $14B annual revenue) semiconductor manufacturer estimated the annual worldwide Pb reduction per 1,000,000,000 integrated circuits was only equivalent to ~100 automobile batteries.

Wow!  That is simply amazing on the face of it.  Over the years, I have probably found and carted at least 10 old car batteries to the recycling center for a few dollars each.  According to the Kostic paper:

(Computer chip manufacturer) Intel’s efforts to remove lead from its chips have so far cost the company more than $100 million and there is no clear end in sight to the project’s mounting costs

Wouldn’t $100m be better spent on other, more pressing pollution issues?  Fukushima, springs to mind.

Further, the replacement metals used in electronics have some problems of their own.  They may be better for the environment, however, they lack testing and are

Not optimized for high reliability, severe stress, long life applications

Further, replacing parts in legacy equipment using ROHS parts and solder may present problems with bonds between dissimilar metals.  Thus, making field repairs, or any repairs impossible.

Many of the newer solders and circuit boards use Tin (Sn) as the finishing metal.  There is a problem with tin, known as Tin whiskers.  This was first noted at the Bell Labs in 1947.  Small hairs grow out of the surface of the metal, acting as short circuits, and at higher (above 6 GHz) frequency RF, antennas.   This happens with other metals such as Zinc, Silver, and Gold.

Silver Sulfide Whiskers on circuit board

Silver Sulfide Whiskers on circuit board

As you can probably deduce, this can have certain detrimental effects on the performance of the circuits in question.  I can imagine all sorts of strange behavior from controllers and other bits and parts of equipment.

I don’t know how prevalent this is in Europe where the directive has been in effect for 6 years or so.  It would be interesting to find out.  I also wonder how many US manufactures are adopting RoHS as the de faco standard in order to do business in Europe.


A pessimist sees the glass as half empty. An optimist sees the glass as half full. The engineer sees the glass as twice the size it needs to be.

Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof; or abridging the freedom of speech, or of the press; or the right of the people peaceably to assemble, and to petition the Government for a redress of grievances.
~1st amendment to the United States Constitution

Any society that would give up a little liberty to gain a little security will deserve neither and lose both.
~Benjamin Franklin

The individual has always had to struggle to keep from being overwhelmed by the tribe. To be your own man is hard business. If you try it, you will be lonely often, and sometimes frightened. But no price is too high to pay for the privilege of owning yourself.
~Rudyard Kipling

Everyone has the right to freedom of opinion and expression; this right includes the freedom to hold opinions without interference and to seek, receive and impart information and ideas through any media and regardless of frontiers
~Universal Declaration Of Human Rights, Article 19

...radio was discovered, and not invented, and that these frequencies and principles were always in existence long before man was aware of them. Therefore, no one owns them. They are there as free as sunlight, which is a higher frequency form of the same energy.
~Alan Weiner

Free counters!