Instructables

Custom PCB Prototyping using a Laser Cutter

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I am going to walk you through the process of prototyping a Printed Circuit Board using a laser cutter and supplies from your local Radioshack and hardware store.  This is a process I have perfected after several prototypes I created as part of my thesis, modular//neuroid.
 
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Step 1: Prepare the board

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Remove the bare copper PC Board from the plastic being careful not to get oily fingerprints on it.  Place it on a clean, suitable spraying surface (newspaper or cardboard are great). Using flat black spray paint (I used Krylon brand) coat the copper 3 - 5, allowing time for each coat to dry before applying the next.  If your PC Board is double sided, be sure to repeat this step for the other side.  By the end of this step, your board should look completely black, no bumps or unevenness, and certainly no copper visible at all.

Step 2: Prepare your file

Most laser cutters use vector files to print. Ours (an Epilog Legend 36 EXT) can print PDF or Adobe Illustrator files.  To build a correct schematic, export the footprint of your components (in this case female mini-USB ports) as vector files from Eagle or Fring.  Import this to Illustrator, and build your own traces.  Keep in mind a few things:

• we want the laser cutter to burn away everything that is NOT a trace, therefore the background is black and our circuit is white
1.5pt lines are the smallest that can be drawn
•  For text, no smaller than 5pt font, and should be placed as a negative inside of a box, otherwise it will get etched away
• If you are making double sided boards, finish your front side and then mirror.  This is the easiest way to keep things lined up with each other.
Be as efficient as possible : cram as many as you can together, it will make cutting boards later easier as well

antpgomes1 year ago
by any chance did anyone tried with a vls4.60? I assume the black coating is doing just the same as a metal marking compound would do. Am I right?

Thanks in Advance
Thats brilliant! I can't wait to try to it out. If only I had my own laser cutter... Fortunately a friend has one. Would something like this be suitable for the board http://www.digikey.com/product-detail/en/PC55/PC55-ND/28472 ?

Are there any specifications for the type of board? I read about one Radioshack board where the copper would separate from the board when it was heated.
rfjhh4 years ago
What are you using for laser cuter?
jmsaavedra (author)  rfjhh4 years ago
Epilog Legend 36 EXT
With what power laser?
shanes10072 years ago
Like it! Definitely think laser etching is preferable to chem etch

http://www.lpkfusa.com/pcb-etching.html
capt.tagon4 years ago
Quote in first step "Remove the black copper PC Board..."

Probably should be "blank copper PC Board"?

It isn't black until after you've spray painted it. ;^)
jmsaavedra (author)  capt.tagon4 years ago
corrected!  thanks!
You're welcome. Thank you for giving us instructions on another means of masking PC boards. I've got to see if there is any interest in our area for getting some sort of communal laser equipment set up. The initial $20k price tags kind of put me off back when.
Try searching your area on hackerspaces.org. Alot of Hackerspaces/Makerspaces have access to laser cutters.
josheeg4 years ago
I really like this technique where can I find a small or low priced one of these machines? less than 5k. or how can I get access to one?
Do you have a Techshop near to you? They have laser cutters available.

This is my local one -

http://www.portlandtechshop.com/

There's one Menlo Park as well. Don't know other locations I'm afraid.
I live in albany ny where is the closest one?
You can also check out Hackerspaces.org
Closest to you is http://www.techshopdurham.com in N.C.

We have a nice laser cutter, and are making room in our new location to add a second one.
I've been assured that cutting fiberglass (SiO2) with the Epilog laser is safe.  No highly toxic fumes.

So you can copper etch the PCB's as "panels", then put them back in the laser to cut out the individual boards using the board outlines.  Assuming you didn't leave copper over the board outlines.

It is easy, it is quick, but the edge can be a little "ugly". The fiberglass fibers etch unevenly, giving a ragged edge, and it tends to be discolored.  A few swipes of a file will clean the edges up.

So take into account the filing needed and allow +/-20mils for alignment accuracy when planning your board outline to nearest layout features.  30-50mils, depending how much filing you plan to do.

You can also try to cut vias with the laser, but I had registration problems on the order of 5 to 20mils when taking boards out and putting them back in later.  So I couldn't get the registration accurate enough for this to be viable.
it's not the SiO2 that would be the issue, or even the part that's being affected much by a laser. It's the epoxy or plastic type material that the fiberglass is impregnated. There also is normally fire retardant, usually bromine.

A real high powered laser could at most melt the SiO2, but will not burn and cut it.

so, cutting circuit boards with a laser cutter may be a bad idea.
divaa4 years ago
 Hey is it possible to just cut deeper into the copper and skip the etching step?

tank1357 divaa3 years ago
no, the laser cannot cut through the copper. This is a similar process to etching brass
mojoatomic4 years ago
Good tutorial - I' ve been using the laser technique for about 4 mos now and am very pleased with it (overall) - but I'm not pleased when it comes to cutting the boards out... what technique did you use??? Your cut boards are far nicer than mine.

Also, give auto primer a try - it etches the copper making the paint stick much better and you can get away with two coats.

*Also, for those interested, I've got a Epilog Helix 45w, and the best setting for me is super hot, medium speed, bottom up engraving. As the author said, you *DO NOT* want to burn twice as the results are always less predictable.


jmsaavedra (author)  mojoatomic4 years ago
Oh, cool auto primer trick -- i'll try it out.

As far as cutting the boards, I used a bandsaw.  It worked nicely, however BE WARNED: it produces quite a bit of dust, and this FIBER GLASS dust, which is VERY HARMFUL if inhaled.  I tried a couple other things like scoring and snapping, etc, and they just produced cracked boards like the one pictured below.  That's my partner in crime (aka the godfather) who was trying to find healthier, safter alternatives to the bandsaw. None worked, hence the disappointed face.

Link some of your projects! I'd love to see.

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The best method I've found for cutting circuit boards is a sheet metal cutter.  Makes perfect cuts with very nice edges.  The only issue is you can only get straight cuts!
I agree, they do make perfect cuts - but where can the common man (like me) get one they can afford? I've used the air over hydraulic ones, but they'll set you back $5000 clams. Hve you found (please say YES!!!!) an affordable one that works?
TechShop locations all have sheet metal shears that you can use.
you know those cutters in art rooms? the ones that have a grid on the plate...those will work with pcb clad board which is the copper sheet you see in this video....well those cutters will definatly work and they cost around $20-$200.......... depends on the size
Scoring works for me if I pass the blade a few times at different side to side angles (perpendicular to the straight guide edge). Sort of taking out a V shaped groove in the board. Then snap over a sharp edged surface. Plus it helps if you're manly when you are scoring the board I guess :)
How do you get 2-sided alignment? 

I was getting 5-20mil variations between lasering the top and bottom, so the through holes didn't line up without going to something like 30/15 layout on the bottom.
mattve4 years ago
did you used the laser to cut the boards as well, or a different method?
charles.liu4 years ago
i am a sales in laser cutting machine company in china, we have used laser cutter like this been a long time, this is not for AD,if you need mroe information about this, let me know.
sales.jinzulaser@hotmail,and welcome to our website www.jinzulaser.com 
ZrvZ4 years ago
how precise  are you able to do a pcb with this? I see that you state 1,5 point as the minimum trace  width but what does that translate into in mil? How much clearance do  you have between traces?
captnkrunch4 years ago
Exactly how do I export a vector file from Eagle?  I see how do do PNG images but not vectors.  Thanks.
jmsaavedra (author)  captnkrunch4 years ago
File -> Print -> PDF...

then open this file in Adobe Illustrator or the like.
nodyeliab4 years ago
Very nice job, what power setting are you using? Thanks.
jmsaavedra (author)  nodyeliab4 years ago
I believe the best results happened with full power and medium-ish speed.  It's always good to do a small test, perhaps on a corner of the board to be sure you get through the paint -- remember, you want to avoid lasering the same board twice at all costs!
xtank54 years ago
Cool method.  Why don't you try cutting away the copper with a laser and save a step or 2?
jmsaavedra (author)  xtank54 years ago
This would be brilliant! Unfortunately, laser cutters cannot cut through anything metal.  They can, however, etch the surface of metals - which is why it is safe to laser engrave your ipod or computer.  But alas, it can't go through the copper of a PCB. Also, I'm unsure of what would happen if you attempted to laser fiberglass directly, which is something that would happen if the laser penetrated the copper - might produce harmful byproducts (gases).  Good luck on your prototyping!
The warranty on  an Epilog laser states that if you try to laser anything containing Chlorine, the warranty will be voided.
@xtank5

Copper fumes, and for the type of laser cutters being used by our suppliers to fabricate wood, plastic and metal model airplane parts, you'd have slots between the traces.

You're using an ablative process here that is dependent on the melting point of the various materials, copper being more resistant than the thin layer of paint, or the fiberglass reinforced epoxy below.

Is anyone producing a pulsed laser system that has adjustable cut depth? And at what cost?