PCB four 80 mill wide traces

[saramah]

hI
Here,
https://www.edaboard.com/showthread.php?228130-Pcb-trace-width-for-10a-current DeLorean said,

It depends how much voltage drop you can tolerate. Even a 25 mil wide trace can take quite a few amps without burning open. I also recommend you use 2 oz. copper but that limits how narrow a trace you can put down for logic components. I have run 40 amps on four 80 mill wide traces with 2 oz. copper. I use a trace on both sides of the board and it was driving two loads. Traces were very short so voltage drop was minimal.

You can compute the resistance of the trace by computing the circular mill area and length.

What is mean by four 80mill? Is it like, mask-80-mask-80-mask-80-mask-80-mask on a surface(top/or bottom). if so then what should be the mask width?
tnx.

 

[marce]

It means four traces 80 mil wide, 320 mil in total... Not really recommended for 40 A.
Look for Saturn PCB Toolkit, download it and have a play.

 

[c_mitra]

Although solder has about 10 time higher resistivity compared to copper, you can put a very thick bead of solder on the copper layer. This is the common trick used in SMPS for desktop computers.

 

[saramah]

hi,
If resistivity of solder is more than CU, then resistance will be more and curren will down, so, how thick bead of soldere on cu will carry more current??
tnx

 

[smijesh]

If resistivity of solder is more than CU, then resistance will be more and curren will down, so, how thick bead of soldere on cu will carry more current??
tnx

Simple Suppose your cu track have 0.1m Ohm resistance, your solder mask (bead ) have 1 m ohm then effective resistance will be 0.09 m ohm
We can increase the thickness of solder mask so the resistance will reduce

 

[marce]

Although solder has about 10 time higher resistivity compared to copper, you can put a very thick bead of solder on the copper layer. This is the common trick used in SMPS for desktop computers.

Bad Advice, do the job properly with copper, this will not pass UL or other safety measures.

 

[c_mitra]

this will not pass UL or other safety measures.

Can you please tell which specific test it will not pass?

These standards are basically safety features and putting a thick solder bead does not compromise the safety otherwise.

 

[marce]

You cannot use it for extra current capacity. Its an old practice that went out of date 25+ years ago. Calculate the correct copper required at the required max temp rise and do the job properly. Its hard to control the amount of solder added and iit is an extra production job if wave soldering is not used.