Electronics > Beginners
PCB LASER CNC
oldschool:
Hy
I am thinking to build smal cnc with laser of 500mw to1w with 405nm to exspose photoresist on pcb plates. But cant find some stuf on internet wich are bothering me.
I have read that laser shoud have over 30Khz somthing :wtf: becose it cut nicer. So dc laser is of the question or what? What is pwm or tll in lasers? I thinked that lasers are dc powered not high voltage high frequency, at least form ebay for 30 dolars.
Next stuf is how to program this beast. If i use target 3001 program for drawing pcbs, how to convet in some usful file that for exsample mach3 program can read it. If i understand corectly laser cuting goes up and down over the whole board with litle steps. I understand g code ( i work on cnc machines) , but how do you convert picture from target to this kind of movement of the machine. Is there eny programs for this or how it is done. :-//
I woudbe realy hapy if somone can give me an advice or two.
Thank you wery mutch.
What have i done.
- i looked on the internet
- i ask on another forum replies zero
- i looked for cnc kontrolers online and pricing
- i loked at the you tube where i found some videos
- ask frends
- buyed 3 nema steper motors loking for more powerful controler or polulu stuf
Domagoj T:
May I ask why are you doing this?
If you need a DIY way to produce PCBs, toner transfer is much easier, cheaper, faster and more accurate.
If you are doing it because you will end up having a CNC laser too, well, you're not going to cut much more than paper with 1W.
As for how to do it, you can either convert the traces to BMP image and do a raster engrave job, or covert GERBERs to gCode to do vector job.
jeremy:
--- Quote from: oldschool on May 03, 2019, 01:35:13 pm ---I have read that laser shoud have over 30Khz somthing :wtf: becose it cut nicer. So dc laser is of the question or what? What is pwm or tll in lasers? I thinked that lasers are dc powered not high voltage high frequency, at least form ebay for 30 dolars.
--- End quote ---
I am guessing that what you have read refers to ablating (vaporising) the copper, where you would likely use a Q-switched laser that operates at something like 30kHz. These lasers are quite large, need water cooling and cost something like $50k :) LPKF makes some machines that do this which are more like $100k.
Just exposing the photoresist with a laser diode driven by DC should be fine. Make sure you get a single mode laser (for 405nm, usually only found in blue ray drives) for the smallest spot size.
janoc:
There are some projects on Hackaday that did this - both a laser plotter and actual laser printer for exposing photoresist.
However, apart from having fun with lasers (and burning your eye out) this isn't a very practical method of making PCBs. It is very slow (realize that that tiny laser spot has to pass over every single spot of your board!) and very very sensitive to vibrations from your gantry (or whatever rig you use). Also perfect focusing and intensity control of the beam are a must (otherwise it will bleed outside the intended trace). When laser cutting or engraving 0.2-0.5mm is not a problem but with PCB tracks 0.1mm error can make the board unusable already.
The Hackaday project didn't use a 500mW module from China but one of those Bluray laser writer laser assemblies that come with focusing coils and all that - that is actually essential unless you only care about very rough boards with huge traces (but then you probably could just draw the tracks with a sharpie as well).
A better method is to either make transparencies, or, if you don't want to mess with those, some people hacked cheap LED projectors by replacing the light source with an UV LED.
ptricks:
I tried this method of doing pcb. I even built the MPCNC machine off thingiverse.
The problem you are going to have is that PCB boards are not 100% flat and so when you focus on one part of the board and get that nice clean line from the laser and then the laser moves across the board the line thickness will vary from wide to smaller. The machine I built ended up being great for cutting wood or engraving but not PCB.
I still use the pre-sensitized PCB board method which is really really easy if you ever do it once.
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