PCB etching question

[PhiloB]

Getting ready to etch first .  I've etched enclosures with ferric chloride.  Will the copper etch quicker or slower than the aluminum?

[timbo_93631]

Copper etches much slower!  Enclosures are pretty exciting to etch by comparison with all the heat/bubbling/smoking involved.

[stevie1556]

I've never done an enclosure so can't comment on the etching time difference. However, I've done a lot of home made boards and found that the etching times depends on the thickness of the copper and the temperature of the FeCl. Keep the temperature between 40-45'C and they etch quickly.

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[PhiloB]

What method do you use to heat up the feCl?

[stevie1556]

I cheat as I've got a heated bubble etch tank. Having a pot of really hot water, with a plastic bowl in it with the FeCl would work in terms of heating it. It won't really work if the temperature goes above 55'C though.

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[RobA]

What method do you use to heat up the feCl?

I don't use FeCl so I've never tried this, but when I was looking into it before I saw people talking about using fish tank heaters for this. It seemed like a pretty good idea to me.

I etch with sodium persulfate which also goes faster with some heat. I only do very small batches, so I just use a couple of pyrex pans and make a shallow water bath for it on the stove. I'm not sure that's a good idea with the ferric chloride though.

[PhiloB]

Yeah.  I don't have a thermometer that isn't metal for measuring the acid.  Guess I could get the water (that i would set the container of acid in) about 20 degrees F hotter as a starting point

[PhiloB]

My attempt to transfer toner to the copper was unsuccessful using P'N'P.  it was close but not close enough.  I'll try magazine paper next I guess.  I'm thinking maybe it could be the type of Toner at the place.  Maybe I should try my printer at work?

[davent]

What method do you use to heat up the feCl?

I use a hot water bath to heat the etchant and then also to maintain the temp while etching. A plastic dishpan holds the hot water then a smaller, size appropriate container is "floated" in the bath to contain the etchant and pcb. Any splash of etchant while agitating  the pcb ends up in the waterbath pan rather then staining something that you're going to wish had been protected. I test the bath temp with my hand, no big deal.

dave

[PhiloB]

Nice tip Dave:) Hope to get my toner transfer correct and give it a shot.
BTW, there is copper on both sides of the board.  Any special considerations for double sided?

[davent]

Assuming traces are only going to be on one side tape off the non-trace side so nothing etches, waste of time and etchant to remove the copper. Once etched and you've drilled the lead holes take a larger bit and chamfer all the holes on the non-trace side to eliminate any chance of  shorting.

[PhiloB]

Ah.  That's clever.