FC. The other stuff is just too toxic from what I have read. I do not have good ventilation in my basement.

I do have an unused stack connector to my roof used by my old furnace but the water heater still uses the stack and I question the wisdom of venting fumes up there.

 

Pay close attention to storage. The further away from metal (and pay special attention to house fixtures) and paper the better. This is true of all etchants.

Personally I don't think Muriatic Acid is that toxic, and Hydrogen Peroxide isn't. To each his own.

 

What do you do about the fumes from the Muriatic Acid?

This guy is just using hydrogen peroxide, vinegar and salt but sounds kind of iffy too me.

 

I mix it when I need it, use it, then get rid of it. It is very fast, actual etch time is around 3 minutes, so I do not worry about it. FC is much slower. The speed of etch time means the board tends to come out cleaner. There is less etching under the trace.

I also use very small quantities. It is much more potent that FC. It visibly fumes when you pour the acid into the H2O2, but that is the only time. You can smell the acid, and it does not stink up the house or anything. Like I said, it is an extremely small quantity, much smaller than FC.

I wear the protective gear, and have a glass of water and plenty of paper towels around. I through the small piece of sponge away in the trash.

When I say potent, it will do a lot of boards off that one small batch. It will eat aluminum foil like alka selzer in water, only faster. I still have a lot of FC left, but I doubt it will ever get used. I do not have the staining issues I had with FC, I do not need to heat the liquid, it is self heating, the process is so much faster I do not stand around waiting for it, and the liquid starts off clear (though it becomes translucent green with use) so I can monitor the process easily.

Next time I make boards, which is probably not too far off, I will wash the finished board in a solution of baking soda and water instead of just water. The finished boards tend to corrode a bit faster, my thought is there is still a little acid left when I've finished.

 

Well I am going to have to give it a try then. I do get some mixed results with FC. I will get pitting once in a while. Also if I need to touch up the board with a sharpie, the sharpie ink seems to start to go first. Hopefully there will be less touch up with the laminator. And it would be nice to be able to see

 

I like the speed and reliability of Ferric Chloride, you just need to agitate it a lot. And being warm helps, if you get it about 35'C (ie body temp) it works a lot better than at 18'C (like if you are in a cold room at room temp).

For agitating I use a tilt tray and just enough FC to cover the PCB, so the tilting makes a lot of flow over the top of the PCB. Deeper liquid does not work as well in a tilt tray. Etching is usually 5 to 10 minutes.

 

That's what I use. I only do smaller simple boards by hand (I send out for bigger more complex ones). I just drop them in a little tupperware container with enough FC to cover the board and swish it around manually. Only takes about 5 minutes. It's always done the job well enough for me.

Personally, I was thinking of trying something less caustic. I can have problems with pitting, but I think that's due to my printer. I'm using an old HP LaserJet that doesn't allow me to adjust the amount of toner layed down. I get really good transfers with the laminator, but there's just not enough toner involved to eliminate those tiny pinholes. I go over things with a sharpie where I can and that helps, but doesn't totally resolve the issue. Probably need to try another printer.

 

If you read Tom Goetee's site he mentioned that was caused from using refills, the original HP cartridges don't seem to have the problem. I have found it be true in my case, I use a HP LaserJet 6P. Tom is a member of AAC as well.

 

...
Personally, I was thinking of trying something less caustic. I can have problems with pitting, but I think that's due to my printer. I'm using an old HP LaserJet that doesn't allow me to adjust the amount of toner layed down. I get really good transfers with the laminator, but there's just not enough toner involved to eliminate those tiny pinholes. I go over things with a sharpie where I can and that helps, but doesn't totally resolve the issue. Probably need to try another printer.

Pitting can happen if your FC is too weak and it takes too long, but since you said it takes 5 minutes that's probably not the case on your boards.

I have not seen pitting under the toner since switching to press'n'peel blue, it makes a very solid black as you get the toner plus the blue plastic layer. And it's not as critical how much toner your laserprinter lays down either (compared to just toner and paper method).

 

If you read Tom Goetee's site he mentioned that was caused from using refills, the original HP cartridges don't seem to have the problem. I have found it be true in my case, I use a HP LaserJet 6P. Tom is a member of AAC as well.

Thanks for the tips.

One of the reasons I'm using an old printer is because I bought a bunch of OEM cartridges when I got it and I haven't run out of them yet. So, my problem is not that I'm using refills because they are new-in-the-box HP toner cartridges. It could be because both the toner and the printer are just too old.

I've actually been threatening to get a new laser printer, but it's hard to justify when the one I have does its intended job fine and I still have a couple new cartridges for it. Laser printers and refills are relatively cheap now, but that stuff was expensive when I bought it.

 

Research it, not all toners work well. I understand Brother brand is a lot higher temperature.

What is the model of the laser printer?

 

What is the model of the laser printer?

It's an old sucker, HP LaserJet 4P. Damn thing has been running great for over a decade. Just don't have the heart to part with it I guess. It's definitely the oldest piece of computer equipment I have. That printer has seen everything else upgraded at least twice by now. Guess there's something to be said for HP laser printers, at least the ones made back then.

 

I almost ended up with one of those. I would keep the old laser jets, though you might get another old one. They tend to be a lot more stable and easier to fix.

 

if anyone is looking for a new Laser I can verify that the HP P1102W works well and you can pick it up new for less than $100. I set the paper type to extra heavy and the resolution to 1200 and haven't seen any signs of pitting. The only downside is that it doesn't feed waxpaper or magazine paper as well as some of the older printers with the flat paper path. I use HP brand glossy presentation paper and with decent success.

 

A non-contact infrared thermometer is handy to measure the temp of the exiting PCBs, to know when they are "done" as you usually have to feed the PCB a few times.

What temperature do you consider done? Medium Rare, Well done? How many degrees on the board at output do you look for?

Trying to save passes here is all.


@Spinnaker:

What did you use for a transfer medium? Magazine page or the PCB in a Box RTF, or the generic Photo paper? Those super fine lines are pretty hard to get that perfect with magazine pages is why I ask.

 

I use the 32 mil copper clad board that is available SUPER CHEAP from The Electronic Goldmine. It's thinner than the 62 mil stuff and works fine in my GBC laminator.

Too bad BOTH of my HP laser printers are junk, so I can't do 0.5 mm-pitch LQFP pads. That makes me sad.

 

@Spinnaker:

What did you use for a transfer medium? Magazine page or the PCB in a Box RTF, or the generic Photo paper? Those super fine lines are pretty hard to get that perfect with magazine pages is why I ask.

It was magazine paper. I'm anxious to do a more complex board and lee how that turns out.

I might try Bill's idea again and use wax paper. I like it because it is easier to line things up but last couple of times I got poor results. Maybe it will do better with the laminator.

It would be interesting to try two applications of toner. Wax paper might make lining up the second copy easier but something tells me it would smear.


With the success of toner transfer, I am surprised no one has come up with a printer that prints direct to copper or at least a hack of a laserjet.

 

I tried a bunch of different magazine papers and found Elle magazine paper works exceptionally well for some reason. It just lifts right when soaked in water in about 2 minutes, zero rubbing or brushing.

I was also thinking that, why wouldn't it be possible to print directly to a PCB with a laser, but I think there's some inherent problem with copper as a medium. The drum uses an electric field to transfer the toner and I don't think that works with copper. Also, any rough edge on the copper might scratch the drum and wreck it.

I've seen modded ink jet printers that print directly to PCB, but it can be hard to get them to work well from what I've read.

In any case, a direct print method sure would be convenient.

 

With the success of toner transfer, I am surprised no one has come up with a printer that prints direct to copper or at least a hack of a laserjet.

That'd be nice huh?

Google will show you all sorts of things folks have done with hacked INKJET printers, printing directly on copper and using the ink as the resist, but the problem is that a LASER printer uses a printing method that is inherently incompatible with printing to a metal surface.

The inkjet printing stuff is interesting though - and there's no reason a manufacturer couldn't commercialize the process. If you can buy a cheap inkjet that prints on CD/DVD media, why not PCB's?

 

I'm wondering what kind of ink you would need for resist?

I would think if you could get it to feed that would be half the battle.