Re: Heat effects on electronics & plastic


Ah, but that's not 'digital' electronics -- bridge rectifiers fall into
'linear' electronics category.
And, the parts don't degrade at 140F. They are to be derated at these temps
but not degraded - big difference.
You will also note that the bridge rectifiers on the heat sinks are often
above 212F (100F) and will sizzle if touched (or burn logo's into skin).
This isn't a fault of the part but rather a poor board design.... Other
than cheapness, there was no reason these should have run so hot.

I don't agree with that article you link to at all. Silicon has absolutely
no problem running at 100C over sustained periods. Cheapy computer power
supplies (such as the OCZ's at the pcpower.com website) don't fall into the
higher temp category ... but not due to silicon failure but rather due to
cheap parts and cheap design. There is no reason that the same power supply
can't be designed to run at the elevated temperatures other than cutting
corners in heat sinks and capacitor types. I've been designing military
systems for years and they must pass prolonged exposure to all sorts of
temperature extremes. And have never had a single heat related failure
after thousands of "shake-and-bake" tests.
Commercial grade digital electronics cannot withstand the extremes as much
as the military grade parts - but they still have a very wide range.
Normally, the older digital electronics (1970's & 1980's) had a high end of
75 to 80C (roughly 170F range)... most newer digital electronics (1990's and
newer) can withstand sustained temps greater than 100C.

-- Ed



"PT" <zeecarr1@xxxxxxxxxxxxx> wrote in message
news:f4449fb6-11d1-4f21-a717-82bd7ba24ebb@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Heat is the single biggest factor in the life of silicon based
electronics. Look at the data *** for the bridge rectifiers in WPC
machines. They recommend never running them without heat sinks and
their performance starts to degrade at a case temperature of 140
degrees F. After a WPC machine is powered on for an hour the backbox
air is 120+ degrees. The BR is much hotter than that if you touch
it.

A properly set up low volume cooling fan system does not hurt a
pinball machine. I built one for my AFM five years ago and haven't
had a single problem. The boards are clean as a whistle too - no
extra dust build up. The air temp inside the backbox never gets more
than 5 degrees above room temp. This means the silicon components are
running as much as 40 degrees cooler.

Here is an article that discusses the effect of heat on silicon
electronics. Pay close attention to the second paragraph:

http://www.pcpower.com/technology/optemps/

John



On Jun 26, 7:16 pm, thehaze <lowrad...@xxxxxxxxxxx> wrote:
Moderatly high heat (say 100-130 degrees) for a short duration is not
particularly harmful to electronics or plastics.

Different story if your pin is turned on. Electronics, especially
digital will start to fail as low as 100, and one chip going bad can
cause a domino effect and take a lot with it. I see many failures
listed hear and wonder how many are from that cause.

btw do pins have cooling fans? I never noticed going over the
pictures.

The effect of heat on plastic (at least the ones I know like PVC,
styrenes, polys) is basically accellerating its aging, and aging
brings brittleness. There is a model, that supposedly predicts it and
is used in lab testing. Unfortunately its expensive and very time
consuming. I don't remember it exactly, but as a example, plastic
heated to 130 degrees ages twice as fast. The life expectancy depends
on the quality of the material. Plastic exposed to high heat or
moderate for a long duration will build-up a very strong smell in a
confined space.

Sunlight attacks plastic with UV as well in a oddly similiar way to
how it sunburns us and can cause cancer. It breaks molecular bonds
and creats those free radicals.

Plastic is also subject to oxidation deterioration which humidity
magnefies.


.

Loading