by Nick de Smith of
used here by permission.
Minor modificatons (which are probably to blame for any bugs) by James Newton.
This page calculates approximations to the ANSI/IPC-D-275 and IPC-2221 design standards for PCB trace width.
The approximations and rationale are described in Temperature Rise in PCB Traces, equations 13 & 15. by Douglas Brooks, UltraCAD Design, Inc. The original idea for this approach was from Brad Suppanz.
The figures returned by this calculator are to be taken as a guide only. I will not be held responsible for any mishap or loss, either direct or consequential, that may occur as a result of relying on the figures herein.
The trace width formulas are:
I = 0.0150 x dT 0.5453 x A0.7349 for internal traces
I = 0.0647 x dT0.4281 x A0.6732 for external traces
I = maximum current in Amps
dT = temperature rise above ambient in °C
A = cross-sectional area in mils2;
The values calculated here compare very closely with those derived by the UltraCAD PCBTEMP utility, and like the diagrams in the standards documents, are valid up to 35A, 400mil traces and a maximum temperature rise of 100°C.
I've added a recommended track clearance value based on the UL rule:
clearance in inches = 0.023" + (0.0002" x V)
The formulae as it stands is simplistic, but is reasonable for V > 50. Note that there are many international standard for this sort of thing, e.g. EN60065:1994, which for European mains of 230V, allows for about 120mil for Class I (protected by earthing) and 240mil for Class II (double isolated). Note that if there is no conformal coating and the environment is dirty/humid/condensing then all bets are off. Please read the standards documents yourself.
Ideally, keep "hot" and "cold" areas of your board well apart.
Change a value in an input field, then press TAB to move to the next field. The results tables will be updated automatically.
|file: /Techref/pcb_traces.htm, 11KB, , updated: 2008/2/20 17:27, local time: 2020/3/29 12:25,
|©2020 These pages are served without commercial sponsorship. (No popup ads, etc...).Bandwidth abuse increases hosting cost forcing sponsorship or shutdown. This server aggressively defends against automated copying for any reason including offline viewing, duplication, etc... Please respect this requirement and DO NOT RIP THIS SITE. Questions?|
<A HREF="http://www.piclist.com/techref/pcb_traces.htm"> Printed Circuit Board, Trace Width Calculator</A>
|Did you find what you needed?|
PICList 2020 contributors:
o List host: MIT, Site host massmind.org, Top posters @20200329 RussellMc, Bob Blick, Jason White, Sean Breheny, Neil, Allen Mulvey, madscientistatlarge, David Van Horn, James Cameron, David C Brown,
* Page Editors: James Newton, David Cary, and YOU!
* Roman Black of Black Robotics donates from sales of Linistep stepper controller kits.
* Ashley Roll of Digital Nemesis donates from sales of RCL-1 RS232 to TTL converters.
* Monthly Subscribers: Gregg Rew. on-going support is MOST appreciated!
* Contributors: Richard Seriani, Sr.
Welcome to www.piclist.com!