Homebrew PCBs

On 15 Dec 2010, at 16:57, Simao Cardoso wrote:
> 
> You need big currents. Say 50 up to 100A in direct mode (3 times for
> reverse) for a 200x300mm (~100inch) board. Such circuit isn't easy and i
> never did anything similar... It seams an AC TIG welder... Other than
> that is the required voltage for the reverse pulse no matter how many
> hairs i pull off i just can't figure it out, it will be found by
> testing.
> 

Do you have a reference for that current calculation, Simao ?

I was looking at http://www.thinktink.com/stack/volumes/volvi/copplate.htm and they are quoting much lower currents. I was only actually trying to get a 100x160mm area plated (it's the limit of my CAD licence) but even 200x300mm comes out way short of 50A

According to their formula,

	Current 	= [(200/25.4 * 300/25.4 * 2)/144] * 20
		 	=> 25.8A 

For my (100x160mm) setup, it would be:

	Current	= [(160/25.4 * 100/25.4 * 2)/144] * 20
			=> 6.9A

Now admittedly, this is for a DC plating environment, not a reverse-pulsed one, but my reading of the pulse-plating literature implied that pulse-plating *let* you increase the current (to get things done faster, which board-houses like). It didn't *require* you to increase the current. I could be wrong, of course :)

Cheers
	Simon



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