Comments on: Laser etching printed circuit boards

By: Chris pryor

Chris pryor — Sat, 19 Nov 2011 22:19:00 +0000

I’ve been doing this for a few years now. I use any spray i can find. White automotive undercoat seems to work well and has a good contrast with the copper.

I use pcb wizard to produce the circuit design. I export this as a wmf file and import this into techsoft 2D design.

It needs flipping and reducing in size by 5%.

Then with the laser, we have a 30w model, i set it to raster the negative. Full power at 40% speed.

I can do a 300 x 200mm board in 20 mins.

Then i spray it with kitchen cleaner oven cleaner also works but can act as paint stripper. This gets rid of paint residue.

Then into etch tank. Our new toy is a roto etcher. Finished in under 3 mins.

Then rinse, drill holes, remove paint on tracks.

Much cheaper and less time critical than UV boxes, masks, developing etc etc.

Chris pryor

By: woodturner550

woodturner550 — Sat, 13 Aug 2011 21:02:49 +0000

I think I have figured it out…Making laser PCBs.
To begin with I make the art work on Corel Draw 5X, then I copy all of the art work to two new layers, One is positive one is negitive. The positive one is of the copper I want to remove, the negitive one is of the traces and pads.

The real key is the ability to place the PCB in the exact same place in the laser. I made a jig to hold my PCB and don’t do ANY lasering on the jig, only in the center of the jig which is hollow.

So I first mount pcb in jig after painting and drying for 24 hours. Then laser the paint where the copper is to be removed. Etch the board, rinse, dry. Remount the board, laser the traces and pads and it is finished. Drill the holes for non surface mount parts.

By: Chris Phoenix

Chris Phoenix — Sat, 11 Sep 2010 20:48:26 +0000

Dave: Put wet paper under the mylar in your laser. You can cut 0.5 mm SMD pads with this method. The power setting is much less finicky. I think I do 100% power, 50% speed, 5000 Hz, on a 45 or 60 watt Epilog, but I didn’t fine-tune this because it worked the first time.

Chris

By: Kyle

Kyle — Tue, 25 May 2010 05:55:24 +0000

Update for the 5 people following this hack. Using the same 120W laser I was able to make vias with 100% power and 1% speed. I only had time for one test so far but it seemed to burn all the way through leaving some copper connecting the two sides. I easily unshorted them with a sharp utensil but it would be interesting to see if 120W could really do the trick.

By: Alric

Alric — Tue, 25 May 2010 00:32:34 +0000

Thank you for thinking of me!

By: Kyle

Kyle — Thu, 28 Jan 2010 03:21:24 +0000

I tried the following:

120W etching laser
20% power
25% speed
500 ppi

Wiped board with 91% isopropyl alcohol before painting with rust-o-leum flat black (24 hr dry time). Etched paint off. Removed paint splatter from pattern with a light rub with alcohol. Be careful, too much pressure will remove all the paint. Bathed in Radio Shack Ferric Chloride for 18 minutes, agitating the whole time. Removed remaining paint with alcohol, scrubbing hard.

Results were amazing. I tested traces as small as .3 mm and they came out perfectly. This method is the best I have ever seen. If you can get your hands on an etching laser (try your local university), I highly recommend it.

By: Dave

Dave — Thu, 24 Sep 2009 05:43:18 +0000

Very interesting. I may try this for SMT stencils. I usually send PCB’s out, but I’ve been looking for a good solution for cheap solder paste stencils.

I have an old and crotchety Epilog Summit that still does 10W or so. I’ve tried making stencils in drafting mylar, but the power setting is just too touchy, there is a fine line between getting a clean cut and getting goo.

The best material I’ve found so far is 17lb drafting velum, which makes a decent 2 or 3 use stencil. 0.8mm lead pitch TQFPs are almost doable but not reliable, and I’ve not had good luck with anything finer pitch. Works great for SO parts and 0603, etc.

So I’m thinking I’ll try your trick, but use 0.003″ brass sheet metal. That should make a decent stencil.

-dave

By: Nabeel

Nabeel — Sat, 06 Jun 2009 12:27:50 +0000

0013 400019331 000421 EACH 1
BOARD , PRINTED CIRCUIT: FUNCTION: UV
EPROM; ADDITIONAL DATA: UV
EPROM,M27C1001-10F1 128KX8BI 1MB, TS
STOCK NO. 169-3439, MFR: ST
ELECTRONICS, MFR PART NUMBER:
M27C1001-10F1 FDIP32W, USED FOR MARK V
CARDS. FOR GE GAS TURBINE INSTALLED IN
ASIR POWER STATION. GENERAL
ELECTRIC/DIELEKTROL/LENTRONICS P/N#
M27C1001-10F1 ST ELECTRONIC P/N#
M27C1001-10F1 APPLICATION:
MFR NAME:REFER TO MFR ON LINE 500
MFR P/N :M27C1001-10F1
Bid Number Bid Send Bid Close
Q090690252415L 02/06/2009 16/06/2009

0005 203647889 000260 EACH 1
BOARD , PRINTED CIRCUIT: FUNCTION:
EARTH FAULT DETECTION; ADDITIONAL DATA:
APPLIC:FOR BATTERY CHARGER; TYPE:
125TPR100; CODE: A6873-010P0T1; VOLTAGE
RATING : 125 VDC; CURRENT RATING : 100
A; SAFT NIFE P/N# B00625400300
Bid Number Bid Send Bid Close
Q090589781255L 02/06/2009 10/06/2009

0007 203647889 000260 EACH 1
BOARD , PRINTED CIRCUIT: FUNCTION:
EARTH FAULT DETECTION; ADDITIONAL DATA:
APPLIC:FOR BATTERY CHARGER; TYPE:
125TPR100; CODE: A6873-010P0T1; VOLTAGE
RATING : 125 VDC; CURRENT RATING : 100
A; SAFT NIFE P/N# B00625400300
Bid Number Bid Send Bid Close
Q090589781255L 02/06/2009 10/06/2009

By: Jack Freeman

Jack Freeman — Fri, 29 May 2009 18:21:12 +0000

Pretty cool!

Check out this place, http://www.etchingpros.com, they do laser etching – on marble slabs up to 4 x 8 feet! Now that’s a serious laser!

By: Kevin

Kevin — Thu, 30 Oct 2008 16:04:45 +0000

Brandon- I also run a 45w Epilog and there is a setting in the driver that lets you do bottom-up engraving. That prevents the redeposit as the laser starts at the bottom of the board and works towards the top with the airflow direction instead of against it. I don’t know which other lasers offer that in the driver though. Makes a huge difference in engraving two-colored plastics.

By: ray

ray — Mon, 11 Aug 2008 10:23:04 +0000

as for garrett’s response, we also did screen printing before we lasered the boards. i think (i’m not sure, i wasn’t involved wit h this process) they printed out the patterns on transparency’s and transfered them onto the light sensitive green stuff (emulsion? it’s been awhile) but that wasn’t very good for tight boards. some of the paint would smear over and connect tracks. so in the end we did it all with lasers as part of our high school tech-ed class.

By: ray

ray — Mon, 11 Aug 2008 09:29:31 +0000

we did this in high school in 2000, we used a thick blue paint from our graphics department, and etched off the paint using a negative of the circuit with our wood shop department’s etching laser.

By: garrett

garrett — Tue, 05 Aug 2008 11:41:41 +0000

@7: the magical chemical i'm using is 99% rubbing alcohol from safeway on a paper towel. It takes off the residue without destroying the resist pattern. Oh, and the paint I'm using is Rust-Oleum "Painter's Touch" flat black from Home Depot. I go ahead and wipe the copper clad with alcohol before spraying it, though I don't know if it really matters. I'm using a 45 watt Epilog laser at 100 speed and 50% power, 600DPI. That's a little more power than they recommend for painted brass, I wanted to make sure the paint was really vaporized off the surface.

The main thing I like about this method is the reliability. Whatever you put in your PCB absolutely will appear in your resist pattern. Press-n-peel or laser toner transfer, you may not get everything down. With toner transfer on magazine paper, you even have to scrub all the fibers out of the ink. Sometimes I'd spend 15 minutes carefully scrubbing a board and then finally a few IC pads would fall off.

Getting the pattern onto the board requires one overnight drying step, and then 5 minutes laser time, but the pattern will absolutely make it onto the PCB and then very little preparation before etching.

I'm going to do some more experiments; double-sided boards, spraying paint on an etched board and then lasering off the pads to make soldermask, I even have an idea for silkscreen. Lots of fun....

By: andre

andre — Mon, 04 Aug 2008 22:17:37 +0000

re. laser activation of resist:- see my article on using an HD-DVD laser diode to expose resist :)

-A

By: Tyson

Tyson — Mon, 04 Aug 2008 21:09:07 +0000

Maybe the laser could activate the resist on a photosensitive board? Usually that photoresist is UV sensitive, and I don't imagine the epilog uses a UV laser, but maybe you could experiment with longer exposures to the laser. You'll want to keep your environment otherwise dark when you're doing this, because room lighting will eventually expose the whole board.

I found photoresist to not be difficult to expose; when I used it, I used a household compact fluorescent light bulb, and it only took a few minutes to fully expose the board.