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On Aug 12, 2013, at 5:45 PM, Inge Hernefjord <[log in to unmask]> wrote:

> The fear of silicon in electronics has its roots in a Swedish Defence
> report 50-60 years ago. At that time a military component test lab
> performed tests of small signal relays. Thousands of relays were tested
> with numbers of conditions.  A few relays had increasing contact resistance
> after thousands of operational elapsing time. Analysis gave that the
> contact had small spots of some silicon product, which was never decided in
> detail. The team made an anticipation, that the silicon somehow had
> 'migrated' from a silicon grease that was used for some reason. The grease
> was not on the PWBs, but had been creeping all over the equipment, and had
> finally found its way on inside of the relays. It was called 'silicon
> migration'. Relay failures were the most feared in the military boxes at
> that time. Note that the relays were low contact force constructions, so
> called 'tongue' relays. Power relays were not involved in the risk group.
> Personally, I have analyzed hundreds of reported relays during decades, and
> have never seen contact issues caused by silicon. We use silicon products
> of all sorts since the 60's and have no silicon issues. I talk about
> millions of boards. The academic high priests reported horrible facts
> ,that  increased the fear even more, e.g. a paper that concluded, that just
> a few drops of silicon oil could spread over an area of a football arena in
> short time! I have demonstrated my scepticism lots of times, and assured
> them that the risks are pretty exaggerated.
> 
> Inge
> 
> 
> 
> The use of silicones for electric and electronics protection is as old as
> some military application from the late 1940's. Since then the silicones
> have become one of the most relevant alternatives for electronics
> protection for reliable applications, and its share continues to growth due
> the increase demand of current applications and the limits of organic
> alternatives.
> 
> The term "Silicone Migration" is also rather old, the first articles
> talking on the subject date on early 1950's. Why then, if this phenomenon
> is known and recognized for over half a century the use of silicones is
> well accepted, recognized and in some cases proven indispensable?
> 
> The "Silicone Migration" term is one almost every electrical engineer has
> heard, yet very few actually know its true meaning. Often this term is used

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