PCB design for 200-300A continuous current

Thread Starter

SayaliVaidya

Joined Mar 14, 2023
5
Hello guys,
I am working on a project in Altium. It is a single layer board. Some part of the circuit carries high current 200-300A. I am using 10mm thickness Cu plate each at two horizontal edges of the PCB. And PCB will be solder paste on Aluminum substrate. Still I am worrying about the PCB Cu width.
If I go for 4oz, then trace width will be around 196mm, that is also too high.
Or Should I use planes instead of traces (but this is also tough as Cu will come out of the pins of IC pins.)
Please guide.
 

Irving

Joined Jan 30, 2016
3,991
We need more info. What is the current for? Is it AC or DC. In general a current of this nature would not be transferred over a PCB.
 

Papabravo

Joined Feb 24, 2006
21,262
Hello guys,
I am working on a project in Altium. It is a single layer board. Some part of the circuit carries high current 200-300A. I am using 10mm thickness Cu plate each at two horizontal edges of the PCB. And PCB will be solder paste on Aluminum substrate. Still I am worrying about the PCB Cu width.
If I go for 4oz, then trace width will be around 196mm, that is also too high.
Or Should I use planes instead of traces (but this is also tough as Cu will come out of the pins of IC pins.)
Please guide.
Can you explain why you think this might be a good idea?
 

Thread Starter

SayaliVaidya

Joined Mar 14, 2023
5
Hello guys,
I am working on a project in Altium. It is a single layer board. Some part of the circuit carries high current 200-300A. I am using 10mm thickness Cu plate each at two horizontal edges of the PCB. And PCB will be solder paste on Aluminum substrate. Still I am worrying about the PCB Cu width.
If I go for 4oz, then trace width will be around 196mm, that is also too high.
Or Should I use planes instead of traces (but this is also tough as Cu will come out of the pins of IC pins.)
Please guide.
Hi!
Thanks for the reply. I am going to solder paste the Cu plate at the two horizontal edges of the PCB. (PCB size: 230mmX200mm)
 

Janis59

Joined Aug 21, 2017
1,855
If that are just the AC 300 A I would guess the inch wide and 3 or 4 mm thick copper bar is enough. If that is DC and one side stays capacitor array and another ultra-power igbt "brick", then inductance of bar is murderous important, thus the sandwich line is essential. For my advice, both copper bars in close distance via 0.5 mm insulator produces diminishing of inductance at least 10-20 fold. Third and ultimative best alternative, especially for capacitor arrays are two close planes (plates) divided by thin insulator, and drillings let the capacitor feets each go to the correct plate. Then the parasitic inductance may be diminished near the 100x. But PCB.... if there is more than 5 A - forget it, and if over 30 A condemn it
 

Janis59

Joined Aug 21, 2017
1,855
By-the-way, when readymade copper bars are not available easy enough, the similar qualities gave the copper pipes for plumber jobs. D 15 mm, 12 mm 10 mm, 8 mm, wall 1 mm. For example, 12 mm means perimeter 12*pi()=38 mm and cross section near 40 mm2. At 10 A/mm3 that allows near the 400 A. Before mountage ought be compressed plane. May fix with rivets.
 

Irving

Joined Jan 30, 2016
3,991
By-the-way, when readymade copper bars are not available easy enough, the similar qualities gave the copper pipes for plumber jobs. D 15 mm, 12 mm 10 mm, 8 mm, wall 1 mm. For example, 12 mm means perimeter 12*pi()=38 mm and cross section near 40 mm2. At 10 A/mm3 that allows near the 400 A. Before mountage ought be compressed plane. May fix with rivets.
Hmmm, cross sectional area of a tube \( = \pi . (r_{od}^2-r_{id}^2) \), so for 12mm with 1mm wall area = 3.1416 * (6^2 - 5^2) = 34.5mm2, 14% off 400A is significant, not 'near'.

If the current is not pure DC but is PWM or pseudo-AC then skin-effect comes into play. As frequency increases, the current carried by a conductor goes towards the outer surface of the conductor, and the copper in the middle becomes inactive. The depth of the current, or the active conduction depth, is called the skin depth. (https://www.teslascientific.com/)

At 50Hz the skin depth is 9.2mm ie there's no benefit in a solid copper busbar > 18mm thick
At 20kHz (typical old-school SMPS or BLDC controller), its 0.46mm, ie no point in a trace> 1mm thick
At 200kHz (latest TNY smps chips,etc) its 0.145mm, ie max useful trace thickness 0.3mm
 

DickCappels

Joined Aug 21, 2008
10,232
The busbars should be carrying DC, and AC should be carried by Litz or similar bunched wire.

@SayaliVaidya If you have not made anything like this before, I strongly suggest you start with something more modest, using the same controller chip because you are going to learn a lot about transformers and switching MOSFETs and doing so at hundreds of amps will be very expensive, so learning something modest then scaling up will probably be the easiest way to get to your goal.

Early in my career I had to design 1600 W racks of 400 W power supplies. During one depressing part of the design cycle I emptied the stores of a high-power transistor from all of the local distributors and had hundreds of dollars worth of dead transistors in the waste basket before the design was debugged. I suggest that unless you have done it before, some something on a smaller scale to get a feel for what you are doing.
 
Last edited:

Janis59

Joined Aug 21, 2017
1,855
RE: Irving - that is the reason why SMPS ferrite transformers are wound by litz. The recipe for DIY litz is simple. Beat two nails somewhere in long corridor and wald with spool in hands n-fold to and back. When parallel wire count is full and length is with reserve, just put one end into electric drill and push button for some 3-5 seconds. Your litz is ready.
 

ronsimpson

Joined Oct 7, 2019
3,145
I am making high current PCBs but not single layer. I use 4 or 6 layers. In the high current areas all layers are in parallel. Use thick Cu. Use many VIAs.

Not a good picture. I use "red cube press fit " connectors to get onto the pcb. There are several companies that make the same thing. Todays project I use two of these in parallel. watch the video. There are used in automotive.
1680610076615.png
Better picture.
1680611047562.png

Alltium

By summer I need to push what we are working on to 1000s of amps and I am experimenting with a very different PCB. My board house can make PCBs where the middle layer is not fiberglass but Al or Cu. (1mm copper core or several 0.4mm cores) We do this to cool the parts on the PCB. But I think I can use this layer to carry current.

RonS.
 
Top