PCB Engraving with cheap mini engraver

[Diachi]

Posted this over on LPF but figured I'd see if anyone here had any input too!

Wondering if anyone has tried (and had success) engraving PCBs (Not directly engraving copper, more engraving a "mask") using one of those cheap mini laser engravers found on DX and such (link). Not necessarily one with that laser, but the same idea. I could go up to 2W 4445nm if needed.

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. Of course, if that doesn't work I'd be interested in looking at using PCB with photoresist, exposing it with a 405nm laser.

This of course isn't for large production runs, but for prototype/one off boards for myself.

Appreciate any input anyone has!

[VDX]

... here's a related thread - http://forums.reprap.org/read.php?133,235148

Viktor

[Diachi]

... here's a related thread - http://forums.reprap.org/read.php?133,235148

Viktor

Thanks for the input, much appreciated! I got a little too far into that thread before realizing that it's your thread! What engraver are you using? I imagine it's a little better than one of those cheap Chinese jobs!

[DanBarlow]

I tried that with a CO2 and never got a usable resist. Paint would melt or carbonize and leave a non-etchable residue. Maybe a pulsed laser would ablate instead of vaporizing.
That said, I love the blue photoresist from China. I use a laser printed transparency and a fingernail curing lamp for exposure. Less than a minute of UV and 4 minutes to rinse out the unexposed goo in washing soda.
The edges come out really sharp and it's insensitive to even major thickness variations; I tried a Meyer bar and a breyer to coat the boards and both worked great. I'm going to try applying a thin layer in the manner of shoe polish next and see if it holds up.

[Diachi]

I tried that with a CO2 and never got a usable resist. Paint would melt or carbonize and leave a non-etchable residue. Maybe a pulsed laser would ablate instead of vaporizing.
That said, I love the blue photoresist from China. I use a laser printed transparency and a fingernail curing lamp for exposure. Less than a minute of UV and 4 minutes to rinse out the unexposed goo in washing soda.
The edges come out really sharp and it's insensitive to even major thickness variations; I tried a Meyer bar and a breyer to coat the boards and both worked great. I'm going to try applying a thin layer in the manner of shoe polish next and see if it holds up.

Yeah, that's one of my concerns, that the paint won't be burned of completely or accurately (i.e. the beam burns off some of the paint in the surrounding area, although I guess that may be an engraving speed issue) enough. It seems VDX had good results mind you - sounds like he had to do a little cleanup on the boards after engraving to remove any paint residue so that may be the way I go.

For the transparency you printed, what did you print on? Those transparent sheets that are used for overhead projectors or something else? I may experiment with the photoresist method anyway using a 405nm laser - just to see what works best. Really I just don't want to be repeating the same mistakes that someone else has already made, so that I can experiment with new methods or methods that have already been shown to work.

Another concern is the accuracy/resolution of those cheap Chinese engravers.

Thanks!

[VDX]

Thanks for the input, much appreciated! I got a little too far into that thread before realizing that it's your thread! What engraver are you using? I imagine it's a little better than one of those cheap Chinese jobs!

... I'm bilding/developing my own systems or refurbishing CNC-mills or rigid XY-plotters since maybe 35 Years - so no need the chinese clones

On the other hand, it seems, the Chinese previously copied/cloned my basic lasercutter design from 1995, where I've filed IP's for the type

For PCB-engraving: - I'm using fast-drying paints with high loads of carbon or pigment and clean it after engraving only with warm water, a bit soap and a soft brush.

Fibercoupled IR-laserdiodes with wavelengths of @808nm, @915nm or @975nm (have some with 5 and 9 Watts) works even better with black paint, but the blue 2W-laserdiodes have a smaller spot, so finer details possible.

I'm building and using my own drivers and firmwares+software too -- and had some time to optimize the applications ... so often I'm going a different way, what's not so easy to follow with the "cheapish" mentality

Viktor

[Diachi]

... I'm bilding/developing my own systems or refurbishing CNC-mills or rigid XY-plotters since maybe 35 Years - so no need the chinese clones

On the other hand, it seems, the Chinese previously copied/cloned my basic lasercutter design from 1995, where I've filed IP's for the type

For PCB-engraving: - I'm using fast-drying paints with high loads of carbon or pigment and clean it after engraving only with warm water, a bit soap and a soft brush.

Fibercoupled IR-laserdiodes with wavelengths of @808nm, @915nm or @975nm (have some with 5 and 9 Watts) works even better with black paint, but the blue 2W-laserdiodes have a smaller spot, so finer details possible.

I'm building and using my own drivers and firmwares+software too -- and had some time to optimize the applications ... so often I'm going a different way, what's not so easy to follow with the "cheapish" mentality

Viktor

What you're doing sounds interesting! Wouldn't be surprised if the Chinese cloned your designs, they're good at doing that! With varying results...

OK, good to know there will be some prep work after engraving. Would be interested in trying out fiber coupled IR LDs too eventually, but I'll start with the cheaper 405/445 options I think. 405@800mW may make a good option due to the smaller beam waist.

If money was no issue I'd go the expensive way The aim just now is cheap, rapid prototyping/fabrication. Similar idea to what people are doing with the cheaper end/DIY 3D printers. Plus experimenting is fun...

[VDX]

... good luck! - and yes, fun is sometimes more valuable than money

Viktor