PCB engraving with cheap mini engraver

[diachi]

Wondering if anyone has tried (and had success) engraving PCBs using one of those cheap mini laser engravers found on DX and such (link).

The method I'm interested in is the one where you coat the PCB in black spray paint and then use the engraver to remove the paint. You then etch the PCB using chemicals as you normally would with toner transfer or similar methods.

Toner transfer works but isn't always consistent with the process I'm currently using. If I could have it work more consistently with one of those cheap engravers and a can of spray paint that'd be nice.

Appreciate any input anyone has!

 

[ElectricPlasma]

Hey Diachi, I made a thread on these little engravers a while ago, you replied to it so you probably remember. All of the mini engravers from china, all the different versions, usually all have the same tech in them just in a different form. With mine it burns relatively well, though some brighter materials require a couple passes to turn out complete.

http://laserpointerforums.com/f44/mini-laser-engraving-machine-97498.html

You'll have to create a custom image to "engrave" into the PCB, but that shouldn't be too difficult, hell, you could probably just use MSpaint for it. Because you're removing black spay paint it should just eat right through it, and if you set it fast enough the board won't even be touched by the laser. Even if it does I'm sure it can withstand a bit of exposure.

Again though depending on the thickness of the coat you might have to do a couple passes, especially if you're going at a faster speed. Sorry if I'm missing something, only worked with PCBs a couple times.

Hope this helped

 

[Benm]

I have my doubts on how well this would work.

The problem would be precision, you're basically ablating (i.e. blasting away) paint from areas you want to expose to etchant. This does not remove nice and even pieces, it'll result in jagged edges which could result in fine tracks being etched away while other parts of the board are not finished etching yet.

Also the edges might be damaged a bit so the paint is not really bonded onto the copper along them, leading to rapid under-etching (etchant eating the tracks away from the exposed copper on their sides).

I think it would work much better using photosensitive circuit board material and a 405 nm laser to explose that. This relies on a chemical reaction instead of literally blasting pieces of paint off. Also it's a well proven technology, the only thing you change is from working with a transperancy and a lamp to exposing the layout cut-by-cut using the laser.

You can even apply the photoresist yourself from a spray can, but i would not recommend doing that - just get the premade material. It's not really cheap, but if you build small things that's not a big problem either. A single sided, FR4 fiberglass board with photoresist on it costs about $5.

This is costly if you do big boards, but if you do small things like laser drivers that are only a few cm on each side the material cost drops to a few dimes a piece.

 

[diachi]

Hey Diachi, I made a thread on these little engravers a while ago, you replied to it so you probably remember. All of the mini engravers from china, all the different versions, usually all have the same tech in them just in a different form. With mine it burns relatively well, though some brighter materials require a couple passes to turn out complete.

http://laserpointerforums.com/f44/mini-laser-engraving-machine-97498.html

You'll have to create a custom image to "engrave" into the PCB, but that shouldn't be too difficult, hell, you could probably just use MSpaint for it. Because you're removing black spay paint it should just eat right through it, and if you set it fast enough the board won't even be touched by the laser. Even if it does I'm sure it can withstand a bit of exposure.

Again though depending on the thickness of the coat you might have to do a couple passes, especially if you're going at a faster speed. Sorry if I'm missing something, only worked with PCBs a couple times.

Hope this helped

I do remember that thread!

Thanks for the input! Might need a second pass to clean it up a little. The copper would be fine at those sort of power levels though! As for the image, I'd probably take the image I'd use for a toner transfer and simply invert the colours, so white would become black and black white.

I have my doubts on how well this would work.

The problem would be precision, you're basically ablating (i.e. blasting away) paint from areas you want to expose to etchant. This does not remove nice and even pieces, it'll result in jagged edges which could result in fine tracks being etched away while other parts of the board are not finished etching yet.

Also the edges might be damaged a bit so the paint is not really bonded onto the copper along them, leading to rapid under-etching (etchant eating the tracks away from the exposed copper on their sides).

I think it would work much better using photosensitive circuit board material and a 405 nm laser to explose that. This relies on a chemical reaction instead of literally blasting pieces of paint off. Also it's a well proven technology, the only thing you change is from working with a transperancy and a lamp to exposing the layout cut-by-cut using the laser.

You can even apply the photoresist yourself from a spray can, but i would not recommend doing that - just get the premade material. It's not really cheap, but if you build small things that's not a big problem either. A single sided, FR4 fiberglass board with photoresist on it costs about $5.

This is costly if you do big boards, but if you do small things like laser drivers that are only a few cm on each side the material cost drops to a few dimes a piece.

That's something I was concerned about which is why I posted - I'm not sure how good the quality would be. I couldn't find a whole lot of other examples of people doing it this way, I may need to search some more! Using larger trace size/spacing may help in that regard right enough, although that'd limit what can be produced to some extent.

I had considered the photoresist method too, but part of what put me off of that was more or less needing to use pre-made boards with the photoresist in place for good results. If the paint option won't work then that would be my other choice. There's a couple of projects I'd like to do that'd require boards larger than a laser driver, although not huge.

I wonder if anyone else on here has one of those engravers and some scrap PCB/black paint they could do a small test with.

 

[Benm]

The problem is that you will often need quite a bit of detail, even when using only through-hole components. The absolute minimum you would probably need is the ability to run a trace between 2 IC pins. The spacing on those is 100 mils, but if you want to do the islands properly and run a track in between you need 10 mils precision to stand a chance.

Photoresist pcb's with a good exposure can do that easily, but i have by doubts on the 'ablating spraypaint' approach. I would surely encourage attempting it and sharing the results, i'm just not that conviced the results will be good.

One upside of 'traditional' photoresist and transparancy results is that you can use the same transparancy many times. This is very nice if you need a dozen boards or so, after that it gets cheaper to have them made (though the lead time can be frustrating).

If you want to make over 10 of the same boards i would recommend using a service to do that though, especially since those usually also offer putting on a solder mask and silkscreen. The lack of a solder mask will prove a bit problematic to novice electronic builders, soldering something like a SOIC package is not that easy on boards without a solder mask, smaller form factors are borderline impossible even if you have considerable experience.

 

[diachi]

The problem is that you will often need quite a bit of detail, even when using only through-hole components. The absolute minimum you would probably need is the ability to run a trace between 2 IC pins. The spacing on those is 100 mils, but if you want to do the islands properly and run a track in between you need 10 mils precision to stand a chance.

Photoresist pcb's with a good exposure can do that easily, but i have by doubts on the 'ablating spraypaint' approach. I would surely encourage attempting it and sharing the results, i'm just not that conviced the results will be good.

One upside of 'traditional' photoresist and transparancy results is that you can use the same transparancy many times. This is very nice if you need a dozen boards or so, after that it gets cheaper to have them made (though the lead time can be frustrating).

If you want to make over 10 of the same boards i would recommend using a service to do that though, especially since those usually also offer putting on a solder mask and silkscreen. The lack of a solder mask will prove a bit problematic to novice electronic builders, soldering something like a SOIC package is not that easy on boards without a solder mask, smaller form factors are borderline impossible even if you have considerable experience.

Good point on the traces routed between IC pins! Didn't think of that - still new to this!

I don't think I'll ever need to do a large run of boards - I plan on only doing boards for myself but I guess you never know. You're right though, would definitely get a professional shop to do any large runs - I'd just do the prototypes at home. If I were doing large runs it'd be for other people so the quality would be important.

I actually want to try my hand at SMD without the solder mask so that may be something I work on, I've done it with and it wasn't too difficult. Again though, you're right, it's best to get those done professionally too. I may try out my own silk screening for my own boards, just to make my life a little easier when adding components...

Definitely up for experimenting - Interested to see if anyone else has first though, that way I can avoid making the same mistakes!

 

[Benm]

Smaller parts can be done witout solder mask as long as you don't make the design as small a possible. As long as all goes well you don't need the solder mask that badly, but once you make a mistake (solder bridge ajecent pins on a SOIC or something) it becomes hard to fix. Some flux and proper lead based solder goes a long way though