PCB trace temperature?

[Dennis Clark]

Hi all,

I've seen and used the trace temperature vs. current calculators and
seen lots of information on calculating trace temps. However, I can't
find any information about just how hot you can let a trace get. I
know that copper melts at about 1100 deg. C, I'm pretty sure that the
board will be damaged before that,... So, how hot can a trace get and
still be OK on a board? Where does board damage occur and how hot are
we "allowed" to get a trace?

regards,
DLC
--
============================================================================
* Dennis Clark dlc@frii.com www.techtoystoday.com *
* "Programming and Customizing the OOPic Microcontroller" Mcgraw-Hill 2003 *
============================================================================

 

[CWatters]

"Dennis Clark" <dlc@io.frii.com> wrote in message
news:41c2057f$0$207$75868355@news.frii.net...

Hi all,

I've seen and used the trace temperature vs. current calculators and
seen lots of information on calculating trace temps. However, I can't
find any information about just how hot you can let a trace get. I
know that copper melts at about 1100 deg. C, I'm pretty sure that the
board will be damaged before that,... So, how hot can a trace get and
still be OK on a board? Where does board damage occur and how hot are
we "allowed" to get a trace?

This page suggests 10 degrees...

http://www.csee.umbc.edu/~plusquel/650/slides/PCB_layer_stacks.html

Quote:
"The power-handling capacity of a PCB trace depends on its cross-sectional
area and allowable temperature increase (typically 10 degrees)."

..

 

[Uwe Hercksen]

Don Bruder schrieb:

That would depend almost entirely on how sensitive the board material is
to heat - A phenolic board might be able to cope with (just pulling
numbers out of thin air for the sake of discussion - don't even *THINK*
of considering them to be accurate) 400C, while a fiberglass board might
survive to 700C, and some other material might be able to withstand the
copper actually melting off it without showing any ill effects at all.
(beyond ceasing to function due to all the traces being gone, that is...)

Hello,

wrong numbers, about 150 °C maximal for FR2 and FR4, better qualities up
to 180 °C. Teflon boards are maximal 250 °C.
The higher soldering temeperatures are tolerated only for a short time.

The datasheet of the material used should be carefully read for
applicable temperatures.

Bye

 

[Don Bruder]

In article <41c2057f$0$207$75868355@news.frii.net>,
Dennis Clark <dlc@io.frii.com> wrote:

Hi all,

I've seen and used the trace temperature vs. current calculators and
seen lots of information on calculating trace temps. However, I can't
find any information about just how hot you can let a trace get. I
know that copper melts at about 1100 deg. C, I'm pretty sure that the
board will be damaged before that,... So, how hot can a trace get and
still be OK on a board?

That would depend almost entirely on how sensitive the board material is
to heat - A phenolic board might be able to cope with (just pulling
numbers out of thin air for the sake of discussion - don't even *THINK*
of considering them to be accurate) 400C, while a fiberglass board might
survive to 700C, and some other material might be able to withstand the
copper actually melting off it without showing any ill effects at all.
(beyond ceasing to function due to all the traces being gone, that is...)

--
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