Industrial temperature range considerations
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Jim,
Here in Quebec it is - 35 degree and it is usual at this time of the year. I
made
circuits for external use since many years and I can tell you that low temp is
only considered for ICs and other component, not for the printed circuit itself.
Rene
Jim Thomson a
Here in Quebec it is - 35 degree and it is usual at this time of the year. I
made
circuits for external use since many years and I can tell you that low temp is
only considered for ICs and other component, not for the printed circuit itself.
Rene
Jim Thomson a
Comments
all of my components for a minimum temperature range of -40C to +85C,
including the BASIC Stamp BS2I.
Now that I'm assembling the first prototype, I realized I didn't consider
the circuit board on which all of those components will be mounted. Does
anyone know of circuit board specs to be considered for wide temperature
applications?
I'm having PCBExpress do the prototype boards for me. They look great. But I
couldn't find any info on their site about temperature ranges other than a
maximum of +125C.
Having such a wide range of temperatures makes me wonder about
expansion/contraction. Are there minimum/maximum sizes for trace widths,
vias, etc? Recommendations?
Rene
thomson92009 a
Yes, -35 degree C whish is about -30 F, but with rhe windchill factor we got
as low as -43 C. That what we got this morning and even the remote starter
did'nt work! I had to go out to start my jeep and it needed 3 try before it
finally start
even with a 600 ampere battery! You can feel the oil in the engine was sticky,
the transmission lever were stuck on the middle, you push hard to it to finally
reach the 1st speed position , the brake pedal still high when you push it,
your bocket seat feel like a piece of plywood, and so, and, so.....
Rene
Dave Mucha a
times a year. We do, however, get +100F temperatures fairly often in
the summer.
When I get the prototype working well, I may contact you about real
world cold weather testing.
Thanks again.
> Jim,
>
> Here in Quebec it is - 35 degree and it is usual at this time of
the year. I made
> circuits for external use since many years and I can tell you that
low temp is
> only considered for ICs and other component, not for the printed
circuit itself.
>
> Rene
>
> Jim Thomson a
wrote:
> Jim,
>
> Here in Quebec it is - 35 degree and it is usual at this time of
the year.
I'm hoping you are talking -35 degree C and and not -35F, or course
when it gets down to -40 it really doesn't matter (on a number of
levels)
Dave
>all of my components for a minimum temperature range of -40C to +85C,
>including the BASIC Stamp BS2I.
>
>Now that I'm assembling the first prototype, I realized I didn't consider
>the circuit board on which all of those components will be mounted. Does
>anyone know of circuit board specs to be considered for wide temperature
>applications?
>
>I'm having PCBExpress do the prototype boards for me. They look great. But I
>couldn't find any info on their site about temperature ranges other than a
>maximum of +125C.
>
>Having such a wide range of temperatures makes me wonder about
>expansion/contraction. Are there minimum/maximum sizes for trace widths,
>vias, etc? Recommendations?
I don't know the answer to your questions about the printed circuit
board itself and the layout issues, but I'd be interested to know if
you find any good information on that.
The manner of soldering to the board does make a difference. A good
oven profile soldered board will have a "just right" amount of solder
under the terminations, and the entire board is subjected to exactly
the same heat profile during soldering. On the other hand, if the
contacts and the board are heated unevenly during the soldering
process, local stresses are left on the terminations and the
packaging. That can be further aggravated to the point of failure by
temperature extremes during deployment. The terminations of surface
mount capacitors are particularly sensitive. Another consequence of
stresses is the development of micro cracks in the packaging in the
area around the pin. In a high humidity environment with freezing
cycles the moisture in the cracks freezes, expands and widens the
crack, just like ice tears down mountains. Cold solder joints also
can work at first, but then fail after a few temperature extremes.
The board mounting in an enclosure or with heat sinks etc should not
introduce additional stress. Through-hole parts are less demanding
than surface mount, because the longer package leads can absorb a lot
of the stress and the heat of soldering.
So, I guess the message is, solder carefully, and inspect thoroughly!
-- Tracy
One thing to add.... Deflux!!!! All that extra rosin left on the circuit
board is a moisture and crud trap. Simple rubbing alcohol and a toothbrush
will get rid of most of the residue left over from soldering, but in the
military world we always used vapor digressers, essentially a big tank of
nearly boiling tri-chlor with a refrigerated cloud of vapor above the
liquid. As the cold circuit board was lowered into this warm cloud of vapor,
it condensed on the surface, washing off the rosin and other soluble. Yes,
this needs a vapor hood and recapture system, but talk about clean boards.
One side note. I'm hoping you all use best-grade rosin-core solder. Kestor
was always the most consistent in terms of chemistry. And NEVER GO NEAR
Acid-Flux solder. That's only for plumbing. I've had a few friends try
soldering circuit boards with Acid flux (yes, it really wasn't me) and the
copper traces all turned green and disintegrated in a matter of days. Talk
about meltdown.
Mike Sokol
mike@f...
www.fitsandstarts.com
" One should not increase, beyond what is necessary,
the number of entities required to explain anything"...
-William of Occam-
Original Message
From: "Tracy Allen" <tracy@e...>
To: <basicstamps@yahoogroups.com>
Sent: Thursday, January 15, 2004 1:19 PM
Subject: Re: [noparse][[/noparse]basicstamps] Industrial temperature range considerations
>
> The manner of soldering to the board does make a difference. A good
> oven profile soldered board will have a "just right" amount of solder
> under the terminations, and the entire board is subjected to exactly
> the same heat profile during soldering. On the other hand, if the
> contacts and the board are heated unevenly during the soldering
> process, local stresses are left on the terminations and the
> packaging. That can be further aggravated to the point of failure by
> temperature extremes during deployment. The terminations of surface
> mount capacitors are particularly sensitive. Another consequence of
> stresses is the development of micro cracks in the packaging in the
> area around the pin. In a high humidity environment with freezing
> cycles the moisture in the cracks freezes, expands and widens the
> crack, just like ice tears down mountains. Cold solder joints also
> can work at first, but then fail after a few temperature extremes.
> The board mounting in an enclosure or with heat sinks etc should not
> introduce additional stress. Through-hole parts are less demanding
> than surface mount, because the longer package leads can absorb a lot
> of the stress and the heat of soldering.
>
> So, I guess the message is, solder carefully, and inspect thoroughly!
>
> -- Tracy
>