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Are we being lead astray?

I find it interesting the way so many elements that were considered relatively harmless back in the days of my youth are now treated like highly toxic poisons, even in harmless quantities or exposures.

We all know that mercury is now a big no-no and long-gone are the days when the science teacher would pour a small pool of the liquid metal into the hands of students so they could experience the magic of this very heavy and fluid substance.

In fact, any science teacher that even opened a vial of mercury outside of a roaring fume-hood would most likely be severely sanctioned -- please, think of the children!

The odd thing is that I don't seem to have suffered any ill-effects from my momentary exposure to this liquid -- nor the subsequent exposure which occurred after breaking a whole bunch of mercury switches open and collecting the small pools of liquid they contained.

And then there's lead...

I spent a lot of time playing with lead when I was a kid.

A metal that was super-heavy (making it great for adding weight to the nose of my model gliders), very soft and also handy for the creation of lead-acid batteries.

I recall reading in a science book how the physical energy of a hammer blow could be converted into heat. That experiment involved hammering away at a block of lead. After performing this experiment in my dad's workshop, I was impressed at the amount of heat generated but my mother was less than impressed with the black mess I'd made on my hands -- lead!

These days I'd likely be whisked off to hospital for some chelation therapy if I had ground lead into my skin to this extent and who knows, maybe it ended up knocking a few points off my IQ but I don't think I have suffered too greatly from the events of that day -- and my quest to learn more about science was certainly piqued.

Unfortunately however, lead (just like mercury) is now treated as a deadly poison and we're told that it must be eliminated from the world around us.

For this reason, it's becoming harder to find solder containing a blend of lead and tin. The lead component has been removed to create "lead-free" solder which consists of over 99% tin with a small trace of copper.

The stuff works but it's nowhere near as nice to use as the good old baby-killing 60/40 leaded solder of yester-year.

Industry, driven by those who fear the effects of lead, have introduced global standards such as ROHS which effectively preclude the use of lead-based solder in any electronic device or component wanting to carry this certification.

Unfortunately, there are some very far-reaching effects to dispensing with the lead in our solder, especially where modern miniaturised electronics are involved.

One of these is the growth of tin-whiskers, an effect which sees the growth of fine fingers (or needles) of tin from soldered joints. Eventually, these fingers of tin can grow long enough to cause a short-circuit between adjacent joints or components -- with obviously dire consequences.

With many modern electronic devices having leads that are as close as 0.1mm part, the growth of even a tiny whisker can render an entire board useless in just a few years of use. The increasiong use of BGA devices also means that repairing faults created by tin-whiskers is often uneconomic -- as the offending short circuit can't be seen and special euquipment is needed to remove reball and replace such components.

In fact, according to some information I was reading the other day, tin whiskers are now accounting for a significant reduction in the reliability of some modern electronic devices and researchers are busting their butts to try and come up with solutions.

Of course the simplest solution is to avoid the use of unleaded solder - but that would be politically incorrect and devices made with such would not be able to proudly carry the ROHS sticker.

So, next time your fancy new bit of electronic kit stumbles and fails just outside the warranty period -- check for an ROHS label somewhere inside (or outside). If you find one, chances are you'll have a better idea why your expensive toy is now just junk.

What do readers think?

Do we over-react to the potential for some substances to cause harm?

Now I must get back to making some felt hats...

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