How to decide Track width accourding to current??

[sudheerg]

hello all,
R there any specific standard or formula for deciding width of the track according to current??

I am a PCB designer and have designed some boards but i just used simple logic that u should make width as wider as possible for higher current or power ckts. but this question of specific width for specific current was occured in one of boards where there is not much space and i need to know how can i calculate minimum track width so that track doesnt get burned....

 

[kripacharya]

There are many online track width calculators available. Simple search revealed these .. to start with.

https://www.desmith.net/NMdS/Electronics/TraceWidth.html
https://www.4pcb.com/trace-width-calculator.html
https://circuitcalculator.com/wordpress/?p=25/

 

[marce]

Use Saturn toolkit, figures based on more up to date IPC-2152,
https://www.saturnpcb.com/pcb_toolkit.htm

All those are out of date calculators.

**broken link removed**

 

[kripacharya]

Use Saturn toolkit, figures based on more up to date IPC-2152,
https://www.saturnpcb.com/pcb_toolkit.htm

All those are out of date calculators.

**broken link removed**

You mean IPC-2221 was all wrong ? At least these are quick & free online tools.
It would be interesting to compare results from the two calculators and see differences in the outputs.

Presumably the IPC-2221 will output thicker/ wider traces, since it is more 'conservative' ?

 

[marce]

Read the second link I provided, it explains it all, but to re-iterate IPC-2152 supersedes IPC-2221.
I am not going to argue trivialities, I am just pointing out the NEWER specification and the tool that most PCB designers I know use for their calculations. I don't want to compare results, I use the newer calculators based on up to date research, not 50 year old research, read the bottom link and it is all explained by the IPC.

 

[kripacharya]

Read the second link I provided, it explains it all, but to re-iterate IPC-2152 supersedes IPC-2221.
I am not going to argue trivialities, I am just pointing out the NEWER specification and the tool that most PCB designers I know use for their calculations. I don't want to compare results, I use the newer calculators based on up to date research, not 50 year old research, read the bottom link and it is all explained by the IPC.

Ouch !!!

Yessir bossman.

 

[keith1200rs]

You could look at https://www.smps.us/pcb-calculator.html which calculates IPC-2152 and IPC-2221 values to find out the difference.

Keith

 

[Mattylad]

PCB Toolkit all the way..

 

[kripacharya]

You could look at https://www.smps.us/pcb-calculator.html which calculates IPC-2152 and IPC-2221 values to find out the difference.

Keith

Thanks Keith.

I loved the bit at the end which said .. "Therefore, because of the wrongful assumption, the legacy recommendations for internal tracks happened to be conservative. Note that the new rule suggests the same copper size for all board's layers. By the way, it may seem counterintuitive, but thicker conductors have lower current carrying capacity than thinner ones because of the smaller trace width at a given Ac."

I think I'll stick with my intuition which says thicker trace = higher current.
And 2152 be damned !! Hahahhaha

cheers1

 

[keith1200rs]

I seem to remember I have some heatsink tables somewhere in one of my reference books that show some counterintuitive results. Either thicker or bigger not always being better depending on other parameters. I also remember big differences between copper and aluminium (obviously only applicable for heatsinks but possibly now for metal cored PCBs). I will try to find it.

Keith

 

[keith1200rs]

Found the graph although I cannot scan it at the moment. For a copper heatsink below around 17 square inches, 3/32" has better dissipation than 3/16" for a horizontal heatsink. For a vertical one the crossover point is around 8 square inches. For aluminium the crossover point is at a lot smaller heatsink. It would seem that thicker is not always better from a heat dissipation point of view.

Keith

 

[marce]

Some history of the current capacity charts, maybe studying how this came about and how the new charts are down to proper empirical testing instead of guessing, may change your mind. We use these charts (IPC-2152) for designing high reliability products where failure is not an option, for some of the biggest names, infact it was Lockhead that prompted the initial research.

http://pcdandf.com/cms/magazine/95/6418
http://frontdoor.biz/PCBportal/HowTo2152.pdf
**broken link removed**