[SI-LIST] AW: Pulse current handling capability of PCB
- From: "Havermann, Gert" <Gert.Havermann@xxxxxxxxxxx>
- To: "Deepak V.L" <deepak.vl@xxxxxxxxxxxxxx>, si-list@xxxxxxxxxxxxx
- Date: Tue, 15 Sep 2009 17:18:47 +0200
Dear Deepak,
I forgot to ask for the length of the trace, but anyhow here is some math based
on the assumption of a single surge event approximated as an effective square
pulse with temperature independent resistance of the trace (due to the short
time period). Without coheating of other traces, only the temperature rise of
your trace caused by the current is of interest.
The energy of a surge calculates approximately: E=PI*R*I²*t/2 where t is the
duration, I is the peak current and R is the DC resistance of the trace at room
temperature. Peak power=E/t and average power=peak power*duty cycle (which is
very small in your case, since the current doesn't flow periodically).
The average power your trace has to withstand is then approx:
P=t*PI*R*I²/(2*prt) where prt is "pulse repitition time" (>10s might be
reasonable in your case) and t is pulse width (20ms).
calculate R using the tracewidth, -thickness and -length at the maximum power
level thats allowed (if you have no special requirements, 100W/sqare inch power
density is ok for most double layer FR4 designs to prevent overheating or
delamination.
I hope this helps
BR
Gert
--------------------------------------------------------------------------
Absender ist HARTING Electronics GmbH & Co. KG; Sitz der Gesellschaft:
Espelkamp; Registergericht: Bad Oeynhausen; Register-Nr.: HRA 5596; persönlich
haftende Gesellschafterin: HARTING Electronics Management GmbH; Sitz der
Komplementär-GmbH: Espelkamp; Registergericht der Komplementär-GmbH: Bad
Oeynhausen; Register-Nr. der Komplementär-GmbH: HRB 8808; Geschäftsführer:
Torsten Ratzmann
-----Ursprüngliche Nachricht-----
Von: Deepak V.L [mailto:deepak.vl@xxxxxxxxxxxxxx]
Gesendet: Dienstag, 15. September 2009 14:27
An: Havermann, Gert; si-list@xxxxxxxxxxxxx
Betreff: Re: [SI-LIST] Pulse current handling capability of PCB
Hi Havermann, Pls find the answers below
-is this a periodic surge event (>1Hz) or will it just happen "once a day"?
It is not a periodic surge, It can happen only once when the system is switched
on.
-is this surge current the only current on this trace?
Yes
-are there other traces on the surrounding area that might coheat this trace?
No
-whats the copper weight?
1 oz
-on which layer of how many layers
The traces are in the external layers (dobulb sided board)
Thanks,
Depak
----- Original Message -----
From: "Havermann, Gert" <Gert.Havermann@xxxxxxxxxxx>
To: "Deepak V.L" <deepak.vl@xxxxxxxxxxxxxx>; <si-list@xxxxxxxxxxxxx>
Sent: Tuesday, September 15, 2009 5:46 PM
Subject: AW: [SI-LIST] Pulse current handling capability of PCB
Dear Deepak,
This depends on many factors:
-is this a periodic surge event (>1Hz) or will it just happen "once a day"?
-is this surge current the only current on this trace?
-are there other traces on the surrounding area that might coheat this
trace?
-whats the copper weight?
-on which layer of how many layers
--------------------------------------------------------------------------
Absender ist HARTING Electronics GmbH & Co. KG; Sitz der Gesellschaft:
Espelkamp; Registergericht: Bad Oeynhausen; Register-Nr.: HRA 5596;
persönlich haftende Gesellschafterin: HARTING Electronics Management GmbH;
Sitz der Komplementär-GmbH: Espelkamp; Registergericht der
Komplementär-GmbH: Bad Oeynhausen; Register-Nr. der Komplementär-GmbH: HRB
8808; Geschäftsführer: Torsten Ratzmann
-----Ursprüngliche Nachricht-----
Von: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] Im
Auftrag von Deepak V.L
Gesendet: Dienstag, 15. September 2009 13:51
An: si-list@xxxxxxxxxxxxx
Betreff: [SI-LIST] Pulse current handling capability of PCB
Dear Experts,
Could someone please guide me how to select a trace width for carrying a
100A surge current for 20us over a PCB trace ?
Thanks in advance,
Deepak
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List technical documents are available at:
http://www.si-list.net
List archives are viewable at:
//www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List technical documents are available at:
http://www.si-list.net
List archives are viewable at:
//www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
Other related posts:
