Introduction: Custom PCB Prototyping Using a Laser Cutter

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.

Step 1: Prepare the Board

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

Step 3: Go Laser Go

Laser your file.  The strength and speed of the print will depend on your specific machine. On ours, medium speed with high power were the best settings.  Also keep in mind the number of coats you used.  The only thing to keep in mind when setting the print : laser bottom to top -  top being the side with air vacuum.  This way the vaporized paint won't re-coat already lasered areas.

Definitely avoid re-lasering a second time over. There's pretty much no way to avoid having to do this if you notice you haven't gotten all the way through the paint, but once you figure out your settings, remember them so as to avoid having to do a twice-over.

Step 4: Clean Up the Board

Now as you can see, the result of the lasering is beautiful, however we are not ready for etching just yet.  There is a very thin layer of paint residue left on the copper that will block the etchant solution from working properly, and will slow that process down a lot.  Here's what to do : Soak one end of a q-tip in  rubbing alcohol (ethyl or isopropyl) and spread it on the exposed copper. Try to keep it off of the black paint, because we want that to stay.  Use the other end of the q-tip to rub away, essentially polishing off the copper, making it shiny and ready for etching.  You can see in the second image, the board on the far right has been cleaned, and is shiny and ready to go.

Step 5: Cut Boards and Etch

It is really your choice to cut the boards first or etch the entire board and then cut it afterwards.  I feel that you need less solution and a require a smaller container if you cut the boards first, and then etch afterwards. With Radioshack's Etchant Solution (Ferric Chloride), you only need to use a little more than enough to cover the boards entirely. Once the boards are submerged you need to "agitate" them for about 20 - 30 minutes.  "Agitate" really just means move around -- I simply lifted and dropped one end of the container every 10 - 20 seconds.  Nothing rough, just a slow wash.  After about 5 - 7 minutes you will begin seeing the orange copper disappear and the yellow color of the fiberglass underneath start to come through.  By the 30 minute mark there should be no more orange copper, only black lines on yellow.  You are done.  As the bottle says, flush the excess solution, and rinse the boards with water in a sink.  The solution will stain, so be careful.  It will also smell of a bizarre and unpleasant musk.  This is normal if you use ferric chloride.

Step 6: Clean and Polish

using a paint remover such as Xylene or paint thinner, bathe or wipe the remaining black paint off of the boards.  It will get a bit dirty (as will your hands) but keep polishing and you will get the boards clean, leaving just your brilliantly designed circuit. Success!

Step 7: Solder and Wire It Up

Here's my USB breakout board (prototype 0.3) ready for testing.

Step 8: Repeat!

That wasn't so bad.  You'll notice that not all of them come out perfectly.  The way the paint dried, the laser settings, all have effects on the final boards. You'll learn, and make it better next time. Eventually the circuit will be perfected, and you can pay a boardhouse to do all this for you!

Comments

author
VincentW27 (author)2017-04-06

How exactly can I draw the trace of everything except the circuit in illustrator?

author
jimismycodename. (author)2017-03-10

I can see a lot of confusion and misinformation in the below comments section. Power is not nearly as critical as the wavelength of the laser you are using. Lasers discriminate. For instance, it doesn't matter how much power you have on a CO2 laser - it just won't cut copper. A UV (355nm) or Green (533) and even near IR (1064nm is common) CAN cut copper. As some have mentioned in the comments below, take a look at the Protolasers from LPKF Laser & Electronics (they have various wavelengths optimized for different substrates and applications). If you search YouTube for Protolaser, you will find several video demonstrations. It's actually quite impressive what they can do.

author
illumation_ (author)2016-11-19

Sorry, I don't get the point of all of this. It has been useful when you don't
need the develop process. The laser cut the traces instead of paint, that would be interesting and time/cost/environment saving.

author

Do you realize what type of a laser that would take? A fiber laser that can cut through metal so 30k USD+ The process laid out is for the rest of us mere mortals with a simple $400-5k dollar machine.

author
DanS339 (author)2017-02-10

What kind of laser would you recommend, wattage wise?

author
sebborn (author)2016-06-16

You can cut down on the laser time and use up less etchant if your software will allow you to trace the edges of your circuit. That way the laser will remove only the outline of the traces and is much faster since it verctor cuts rather than doing a raster scan of the board. An added bonus is that you can ground the non-trace areas to provide ground plane to your board.

author
Hammock Boy (author)2013-02-08

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.

author
EduardoN (author)Hammock Boy2015-12-18

Have a look at gabuleu.blosgpot.com

I bought a Shapeoko CNC and upgraded it to have a small diode laser. Not so expensive in the end.

author
DLM87 (author)Hammock Boy2014-12-12

I find that on my 40Watt laser cutter, the copper of a pcb doesnt absorb any noticable amount of the heat from the laser. But any other paint layer above the copper gets 95% destroyed by the laser, just leaving a thin film which is easily removed with a dilute solvent. In the case of brush on paint, i used Metholated Spirits, or for spray paint i used Mineral Turpentine.

author
EduardoN (author)DLM872015-12-18

I believe LPKF uses a UV laser, not an IR one. You probably are using a CO2 laser which emits in the infra red (IR).

author
divaa (author)2010-05-27

 Hey is it possible to just cut deeper into the copper and skip the etching step?

author
versos-tk (author)divaa2015-02-18

No, Lasers cannot cut into metal (commercial lasers).

author
EduardoN (author)versos-tk2015-12-18

Go to LPKF website and search for ProtoLaser. They do it.

author
yaly (author)versos-tk2015-06-11

What about a 150 W radium laser cutter ?

author
tank1357 (author)divaa2011-05-10

no, the laser cannot cut through the copper. This is a similar process to etching brass

author
versos-tk (author)2015-06-11

even with 150w it is hard as the metal reflects light rather than absorbing it.

author
bgrayson (author)2015-04-28

Thanks, friend! Took me 3 tries getting the speed right, I did it going way too fast first off and it didn't make a dent, second time I set it way too slow and I set off a fire alarm. I bought another board I got the right speed and it was so much easier than wrecking a pair of pliers in ammonium persulphate. Thanks a heap

author
JohnR35 (author)2015-03-15

It sounds odd to me that not only on this build, but on other peoples projects, the reference is made to a laser not being able to cut metal. I had a walkthrough on using our new laser cutter/engraver, and even though we were using wood, the honeycomb base plate was cut in the spots where the test engraving was set progressively deeper. Not being familiar with the process yet, ours will do 500dpi, but I dont know what that translates into for font point. I saw a reference to 1000dpi in the manual, but at this moment I cant recall what it was it was for.

author
rhoaste (author)2015-01-30

My concern is that the paint combustion would produce toxic fumes or other containments that could damage me or the very expensive laser cutter filtration system. Did you have to consult the manufacturer of the paint to ensure this wouldn't happen ?

author
PAD-Le-Temeraire (author)2014-11-12

Thanks, I try it with plastifier instead of black paint :

https://www.instructables.com/id/PCB-plastic-mask-etching-with-CO2-laser/

author
antpgomes (author)2013-02-09

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

author
rfjhh (author)2010-02-06

What are you using for laser cuter?

author
jmsaavedra (author)rfjhh2010-02-07

Epilog Legend 36 EXT

author
boconn7782 (author)jmsaavedra2012-09-17

With what power laser?

author
shanes1007 (author)2012-07-16

Like it! Definitely think laser etching is preferable to chem etch

http://www.lpkfusa.com/pcb-etching.html

author
capt.tagon (author)2010-01-31

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. ;^)

author
jmsaavedra (author)capt.tagon2010-01-31

corrected!  thanks!

author
capt.tagon (author)jmsaavedra2010-01-31

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.

author
RyanBouse (author)capt.tagon2012-02-29

Try searching your area on hackerspaces.org. Alot of Hackerspaces/Makerspaces have access to laser cutters.

author
josheeg (author)2010-01-29

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?

author
kissiltur (author)josheeg2010-01-29

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.

author
josheeg (author)kissiltur2010-02-01

I live in albany ny where is the closest one?

author
RyanBouse (author)josheeg2012-02-29

You can also check out Hackerspaces.org

author
frugalguy (author)josheeg2010-02-06

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.

author
SiliconFarmer (author)2010-02-03

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.

author
ksexton1 (author)SiliconFarmer2012-01-11

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.

author
mojoatomic (author)2010-01-30

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.


author
jmsaavedra (author)mojoatomic2010-01-30

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.

4312821704_1a1a49db51.jpg
author
rhoward99 (author)jmsaavedra2010-02-08

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!

author
mojoatomic (author)rhoward992010-02-08

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?

author
TechShopJim (author)mojoatomic2010-12-09

TechShop locations all have sheet metal shears that you can use.

author
chickenpoper (author)mojoatomic2010-02-21

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

author
pfred2 (author)jmsaavedra2010-03-15

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 :)

author
SiliconFarmer (author)mojoatomic2010-02-03

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.

author
mattve (author)2010-04-02

did you used the laser to cut the boards as well, or a different method?

author
charles.liu (author)2010-02-26

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 

author
ZrvZ (author)2010-02-15

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?

author
captnkrunch (author)2010-02-07

Exactly how do I export a vector file from Eagle?  I see how do do PNG images but not vectors.  Thanks.

author
jmsaavedra (author)captnkrunch2010-02-07

File -> Print -> PDF...

then open this file in Adobe Illustrator or the like.

author
nodyeliab (author)2010-02-01

Very nice job, what power setting are you using? Thanks.