PCB source

[m.marino]

Ecat,

The application is for 69V DC @ 15A through 5 4700uf cap's to power 4 drivers with shop temp's going down into the negative numbers when shut down (shop is lightly heated and closed down in evening as not running over 10 hrs per day at present). Back EMF is a possibility (though not highly likely with the AM882 drivers). This is going to be inspected by a professional spark as it is part of a business and needs to fall under normal practices for safety and insurance purposes (which is why I am having to tidy everything up and rewire some safe but not clean pathways on the machine).

You idea has merit, that I will agree but those I have to please in the legal side of the real world are a different beast, they see things in nice boxes and you have to meet that when dealing with coverage and business practice issues. I won't go into my rant on this issue.

Michael

[ecat]

Aha, Michael
So for those of us playing at home:

The peak voltage determines the minimum track separation, theoretically. In practice the minimum track separation may be more about the safety standard your product is trying to attain. Something like PCB Trace Spacing Calculation for Voltage Levels .

Minimum track width is determined by the acceptable rise in temperature above your operating ambient and the acceptable voltage drop across the length of the track. This in turn is primarily determined by the track thickness, the (average?) current and the track length. The temperature rise will be limited by the choice of PCB material, if you are willing to push things that far, which is probably not wise.

Once you've achieved your minimums everything else is gravy.

I am curious. Is the word of a professional spark sufficient? On the one hand you have the external connections which are a sparks domain, on the other hand you have risk of fire and electrocution due to circuit design which is an area not usually covered by sparks. I think for non Baseffa applications my old company used to get away with 'due diligence' and a £50 million insurance policy but I'm sure lip service to CE certification must have featured somewhere along the line.


Now stick a big question mark at the end of all of the above. I'm not preaching, I am asking if my understanding agrees with yours while hopefully providing the rest of internet with sufficient information to draw their own conclusions. And I apologise if I've missed some previous threads that were relevant.


All ideas have merit if they are backed by evidence. Any idea expressed without evidence is opinion and if I don't know the person expressing the opinion I'm sure as hell not going to take their word on faith, I'll either question them or ignore them. It's good to see Jonathan take this on board.

Edit:
I had this post in limbo for a while, at least 2 hours by the looks of things.

I think Jonathan's final paragraph of post #10 lays pretty much all of this discussion to rest. If you're expecting 2.7A design for 5A (?) and suddenly 1oz copper is looking quite good ?

There's some good information on the topic in this thread:
current capacity of a solder loaded track - Page 2

Not that much information really. More build it, test it, see what it does. The guy in post #18 is speaking from 3 years experience and has never looked inside a PC power supply. And the comment on thermal dissipation in post #19 sounds 'out there' to me. I still say if your basic design is sound and safe there is an extra 10% to 40% capacity/safety/luxury available for next to nothing.

I know linking to another forum is not a great reference, but here it is anyway:
DipTrace Forum • View topic - How do i make certain tracks soldered rather than painted

No, that's great. If the basic design is sound then there should be no problem with any solution. The guy does fail to mention that the most likely place for a fracture to occur is right at the component lead, track boundary - in my opinion.

It depends...

Exactly. It all depends on...