Hi! I'm new to CNC, and have a few questions about the micRo, and if I'm heading in the right direction...

My interest in CNC machines would be to etch and drill PCB's. Recently I've been working with boards that have 6 - 8mil traces, use 1206 sized SMD components, and have SOIC sized chips.

With something like the micRo, would it be possible to generate a board in Eagle, generate the G-Code, and etch it? What would be the smallest feature I reliably etch on a board? I realize this may be affected by the thickness of copper, thickness of the PCB, etc, but is there a generic "the lash limits you do a pad on the board no smaller then X by Y millimeters"?

Another question that pops up, what do "home builders" do for via's on a board? put a pad either side and solder a wire between? Other magic?

I'd love to hear about anyone's adventures etching PCB's, and what you found you could or couldn't do! My hope is that if the limits are small enough I might never have to have a big company produce boards for me again... (I've had great results from them, but the freedom to cut my own would be awesome!)

Thanks for any input!

I think this is going to be a test and see thing. The micRo theoretically should be capable of some very good tolerances -- but I think you hit on the key part there with the differences in the copper plating and that type of stuff. I never figured that'd be one of the things I'd be looking to try out, but recently I've gotten a bit into the hardware side of electronics and I'll be trying some board etching. I know some others were planning on doing this, and there was even some thought going around at a pick and place system using micRo. So, I think the potential for all that is there, it's just a matter of working out the details and finding the answers once we get to really test the micRo.

Hi, I've had quite a bit of experience with (chemically) etching boards, but relatively little routing them (as in routing them with a router/dremel). However, if you can find a way to convert gerber to g-code, then you won't have any problems. However, the best success I've had was with a mix of Hydrogen Peroxide and Hydrochloric acid.... Kinda scary to work with, and gave my self plenty of minor chemical burns, but will etch nearly anything, PCBs included. I'm not going to tell you how to do it, since if you're resourceful enough you'll be able to find out how, also it is potentially a gazillion times more dangerous than the normal ferric chloride method (it's possible to accidentally boil the mixture, while releasing chlorine gas....)

Anyways, I'm sure there are gerber to g-code conversion programs out there. So no problem. The smallest feature routable is a function of the tool you use to cut, however, the micRo can maintain positional accuracies (without tweaking or care) within a couple thousandths of an inch- well under the runout of almost all spindles/tools that will fit the micRo. Also- from personal experience with PCBs, the biggest problem with small features will be the tool/bit grabbing the copper (especially for small features) and pulling it off of the FR-4 or whatever you have.

Re: Vias...... I know that there are some rivet-esque things that can function as vias, but I've never used them myself. The normal solution is to make a through-hole with pads on both sides, and solder a lead through it. Otherwise, yes, jumpers are not uncommon for DIY PCBs.

I'll see what I can find on machining PCBs though, since it's a safer, more environmentally friendly, and probably (over-all) an easier method for small and medium runs of boards....

Thanks for the input! If the tolerances are in the low single digit thousandths of an inch (given the right tool, bits, etc), I should be able to make at least some medium density boards... The smallest I've used so far had traces of about 6mil (0.006") , so I think it might be a bit touch and go... that being said, for a lot of designs I could afford to use bigger traces and bigger boards, if I got to turn them around at home (if I'm machining them for cheaper then the commercial prototyping board mills, and have the ability to design and retry at home, it offsets not getting as many boards on a eurocard!).

I'll definitely keep something like the micRo in mind when I finally make a decision...

PCB milling is definitely on my list of things to try. I have a couple of boards I need and haven't yet got around to sending them off to be made. It will be one of the first things I try with my micRo, so I'll let you know how it goes.