Making PCB with laser (no chemical etch)

[mike-d]

Mike,

Direct etching copper with a laser is going to cost serious money.

Tweakie.

I can see a substantial time investment in the software and possibly the controller hardware, but unsure of what type of laser and power would be required. Below is a link to another video interview with more detail about the process where they talk about burning off the copper without damaging the substrate, perhaps this requires a balance of high power and high speed.

Watch "LPKF ProtoLaser S: PCBs at the Press of a Button" Video at Engineering TV

What part do you see as cost prohibitive, possibly the type of laser used?

Mike

[Tweakie]

Mike,

Sorry I should have explained my thinking better.

My little CO2 laser operates at a wavelength which sees copper as the best possible reflector so there is no chance of even slightly etching the surface.

The fibre lasers, operating at a different wavelength, are good with metals but are relatively new technology and carry a commercial price tag. Home construction is doubtful at present because of the lack of availability of materials.

I have a YAG which cuts holes in aluminium in a single burst but I doubt it will touch copper - something for me to try one day perhaps.

I am guessing here but a laser to etch away copper is going to cost upwards of $20,000.

Tweakie.

[mike-d]

Tweakie,

Thanks for the detailed explanation I will start researching the type of laser required to etch away copper, and yes you are probably correct about the price, makes perfect sense. Anyone who might have advice on the laser specs please chime in.

I will also continue to explore the other idea of using a UV CNC laser focused exposure instead of printing a mask and doing full board exposure, neat concept as an experiment, but I think I like your method of just milling off the copper as well.

Thanks,

Mike

[fullspeceng]

We sell a Q switched UV laser system that ablates copper.

Q switched laser means it puts out several kW of power in a ultra short pulse. Only the surface is ablated and everything else stays unaffected.

You are looking at around $60,000 for the system including scanning galvo/controller. We can sell you just the laser diode module for $45,000.

Yag reflects nearly 100%. Only green and UV lasers work on copper. Don't waste your time with other stuff.

__________________________________________________ _____________
Win a free CO2 laser engraver: Full Spectrum Laser LLC

[Rodney Gold]

$60k to make prototype PCB's without any holes etc? I use my co2's to etch all sorts of stuff , the secret is to use a resist that can be sandblasted to remove any residue the laser ablation leaves
I use a polyester based laser friendly vinyl , sandblast after to remove residue and then use a home made heated ferric chloride and citric acid (google Edinburgh etch) spray etcher and achieve cut rates of up to 1mm per minute on copper and about 1/3rd that on stainless steel.
You can use a primer and paint and ablate with the CO2 and then use a household mild abraisive cream type cleaner rubbed on with your fingertips to clear any residue , it works , but often on very small lettering like 1mm high , you can lose the centres of letters like B's , P's etc.

[fullspeceng]

We can make features less than 1mil (25 microns) wide with the UV laser. UV laser can also drill the holes in thin boards.

Using our $60 inkjet kit, we direct print and get 6mil/6mil features at 25x the speed of rastering with a CO2 laser that you need to etch afterwards.

1 mm = 39mil. Even laser printing on toner transfer film /iron on can give you 15mils easily at 10x the speed.

LPFK charges $220,000 for their UV PCB laser system so $60k is a reasonable price for those that need copper ablation.

________________________________________
Win a free CO2 laser: Full Spectrum Laser LLC

[Anath]

I've done this, flat black el-cheapo spray enamel lasered off with a 40W chinese laser as resist, etched in a vertical heated Ammonium Persulphate bubble(fish) tank, then sprayed with TESTORS candy transparent green, then that lasered off the pads as a solder resist, then popping holes in the center of through-hole pads with the laser turned up, and chased with a drill bit.

It's plenty good enough for 0805 resistors, and TQFP ICs (10mil / 10mil trace & space). My etching process is the limiting factor.

I sure wish I had the $220k for the LPKF laser though..

[bbutcher85710]

I am going to paint some black paint on some FR4 to be used as acid resist, and then i'm going to etch away the un-needed paint.... Wanna see some pics of the results? You guys ever try this method?

I have done that with a frequency doubled (Green) Q-Switched YAG laser and it works great. I think CO2 would be even better. You could probably use a CW CO2 laser for that purpose. The biggest problem I had was getting wide enough lines in the paint. Probably de-focus a bit would help.

I used acetone to remove the paint after etching.

Bob Butcher

[bbutcher85710]

From experience with CO2 lasers, I think you may have a problem. Copper tends to be highly reflective and therefore hard to remove with the 10.6 um CO2 wavelength. Once the copper is removed, the CO2 laser will tend to eat up the FR4 substrate. A pulsed CO2 TEA laser with very short pulse width probably could have high enough peak power to do the job, but it will be tricky.

Pulsed green or UV lasers work better for cutting copper, but the cost can be a factor. One job I had involved removing copper from a Kapton substrate similar to a circuit board. We used a frequency doubled Q-switched YAG laser which was absorbed quite well by the copper and removed it. The Kapton substrate was transparent to the green light, so there was little risk of damaging the substrate., It could be a problem for double sided PCB however since the copper might be removed from both sides.

Generally for cutting metal, a pulsed laser with very short pulses is preferred. The peak power during the pulse can be very high, vaporizing the metal, but the average power can be fairly low. Low average power is good to avoid unwanted heating of the substrate.


Bob Butcher

[alpha_one_x86]

Hi, I have CNC + 15W laser 450nm, I can etch PCB without chemical?

[ZASto]

Hi, I have CNC + 15W laser 450nm, I can etch PCB without chemical?

Short answer: NO