I was just having that conversation with our PCB design guy, and
here is what I think we know, and its not much.
The 130 degree C temperature is a NRTL imposition on the maximum
continuous temperature of components touching that board, and I believe it
also tends to set the maximum solder times and temperatures. From a PCB
design point there is another very important specification that the PCB guys
have to worry about which is the transition point. This is a point, so I am
told, were the board transitions from glass to liquid. This would not be a
good thing, and unfortunately neither of us were able to correlate the
component temperature rating with the transition point rating. Seems
intuitive that you would want them to be as far apart as possible.
The 130 degree point also takes into account the temperature at
which traces, and layers start delaminating, but again I don't have the
parametric between the board rating and the temperature at which the traces
start coming off. E.G. UL board rating of 130, but the traces start
de-laminating at 150 etc. Seems that this would happen before the transition
point making it the controlling value, but I am sure waiting to hear from
others about this. Maybe someone out there has the UL PCB standard and can
tell us.
Gary
-----Original Message-----
From: [email protected] [mailto:[email protected]]
Sent: Tuesday, October 10, 2000 10:36 AM
To: [email protected]
Subject: PCB temperature ratings
When a PCB is rated 105C or 130C or whatever, what does that really mean?
Can I really operate a 130C rated board at a maximum surface temperature of
130C for years without being concerned about reliability or safety? Is there
a relationship between de-rating and reliability or safety?
Richard Woods
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For help, send mail to the list administrators:
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