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Author Topic: [REQ] PCB by LASER  (Read 12994 times)
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masster
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« on: May 19, 2010, 01:01:22 01:01 »

hello everyone
I was thinking recently about the possibility of fabricating PCBs in a more elegant, precise and rapid way. And my eyes got caught by some YouTube videos (search for 'CNC laser') describing how to etch plastic, metal, wood etc using modified laser lamps from DVD writers.
Bingo ! So why not making a 2-axes CNC machine for etching copper and drilling holes for PCBs...
I am sure that I am not re-inventing the wheel with this idea, but here is my 2 cents about the advantage of using this technology:
- very precise routes and holes
- possibility of variation of etched track width (or hole diameter) by simply raising/lowering the laser or increasing/decreasing power applied
- no more chemicals, no more toxic fumes
- start-and-forget technology. no need to supervise it
- very quick fabrication
- no need for repeated copper cleaning. just once at the end
- and so on...

The only drawback might be that we need to use the negative of PCB drawings, since we are not etching the routes, but the rest. And a good PCB design can minimise the quantity of copper needed to be etched.

So my question is this: can you share your ideas for further developing this mini-project ? I am sure threre's no need to start from scratch.
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carbontracks
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« Reply #1 on: May 19, 2010, 06:13:53 06:13 »

Laser etching copper is far, far more difficult than materials like plastic and wood.  Its high electrical and thermal conductivity make it very difficult to build up enough heat to make plasma.  Also your penetration depth is practically zero.  To etch copper, and most other metals, you would need a pulsed laser with very high peak power (many kilowatts, at least).  I've never heard of anyone successfully etching (as opposed to engraving) copper with a laser, but its certainly possible given the right laser.  But it will have to be one hell of a laser.
« Last Edit: May 19, 2010, 07:32:37 07:32 by carbontracks » Logged
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« Reply #2 on: May 19, 2010, 06:47:05 06:47 »

carbontracks' name might imply a problem with laser etched boards.  The charred epoxy from the laser etching would tend to conduct, not something desireable for the non-conducting parts of a circuit board.
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« Reply #3 on: May 19, 2010, 10:17:44 10:17 »

Milling or use a photoresist, expose the photoresist using the laser, then chemically etch.
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« Reply #4 on: May 19, 2010, 01:12:06 13:12 »

Maybe you are looking for something like that:
http://www.lpkf.com/products/rapid-pcb-prototyping/laser-circuit-structuring/laser-structuring-printed-circuit-boards.htm
http://www.lpkf.com/products/rapid-pcb-prototyping/laser-circuit-structuring/laser-micromaterial-processing.htm

Unfortunately I think it will not be as easy as you think... :-(
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carbontracks
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« Reply #5 on: May 19, 2010, 02:21:47 14:21 »

carbontracks' name might imply a problem with laser etched boards.  The charred epoxy from the laser etching would tend to conduct, not something desireable for the non-conducting parts of a circuit board.
Not sure where epoxy would come into this..?  But another thing to consider is that if you were able to etch the copper through, then the laser would probably burn through the substrate material (usually fiberglass) very quickly, which would be really problematic.
Milling or use a photoresist, expose the photoresist using the laser, then chemically etch.
Milling is generally the best DIY solution.  A decent CNC can do 6mil traces/gaps and it doesn't take long.  
I'm pretty sure this machine, while nifty, doesn't etch the copper (not with the laser anyways).  It says it's a plotter, which means it probably etches photoresist and you have to give it a chemical etch, like oldvan mentioned.

IMO, using a laser for photoresist etching is kind of silly.  Probably no more difficult than other toner transfer techniques (unless you just happen to be really handy with lasers), and you still have to do a chemical bath.  If you were making boards that included soldermasks, then you could probably also use a laser to etch the mask and that would be pretty useful in itself.
« Last Edit: May 19, 2010, 02:28:21 14:28 by carbontracks » Logged
borberk
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« Reply #6 on: May 19, 2010, 02:47:58 14:47 »

LPFK PhotoLaser S produces PCB. In addition it needs air compressor-blower and ventilation. It's price is abt 75k+5k for blower+...
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« Reply #7 on: May 19, 2010, 03:58:07 15:58 »

To cut a metal substrate a much higher laser power required compared to a dvd writer laser's, around 100 watt or more i think.

If i remember correctly on modern laser pcb drilling machine they use two kind of laser, uv laser to penetrate the copper layer and co2 to cut through the polymer (FR4) base.

-ichan
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« Reply #8 on: May 19, 2010, 07:50:40 19:50 »

Not sure where epoxy would come into this..?  But another thing to consider is that if you were able to etch the copper through, then the laser would probably burn through the substrate material (usually fiberglass) very quickly...

FR-4 is made of woven fiberglass cloth with an epoxy resin binder.  Thus the Epoxy portion of the Glass-Epoxy circuit boards.  Heat enough to vaporize copper will surely damage the epoxy.

EDIT:  After seeing the Photolaser S pages, there seems to be a way to do this.  Now I want one.
« Last Edit: May 21, 2010, 10:51:50 10:51 by oldvan » Logged

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« Reply #9 on: May 20, 2010, 12:23:19 00:23 »

Copper is one of the most reflective metals at most "cutting" laser wavelengths and requires a VERY VERY powerful laser to penetrate into even the thinnest material.  A lot of the mirrors made for extremely high power lasers are made of copper.  It would take kilowatts to penetrate even a micro via in the thin copper on a PCB with typical laser types.  A far UV laser in the kilowatt range is needed even to just pierce "drill" a micro via, and that is likely a superpulsed output.

Not a very efficient or cost effective method unless the absolute tiniest of vias is necesarry.
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carbontracks
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« Reply #10 on: May 20, 2010, 02:56:59 02:56 »

And if there were a laser that could do it, it would have to have a wavelength shorter than 500nm (green), since copper reflects lower wavelengths.  So a CO2 laser would be a terrible choice.
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« Reply #11 on: May 21, 2010, 06:49:52 06:49 »

So how LPKF do it? The cuts looks clean.

From the brochure of LPKF Protolaser S, the electric supply is 1.4KW.

-ichan
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carbontracks
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« Reply #12 on: May 27, 2010, 01:00:28 13:00 »

So how LPKF do it? The cuts looks clean.

From the brochure of LPKF Protolaser S, the electric supply is 1.4KW.

-ichan
Someone told me that it cuts a fine hatched pattern wherever the copper needs to be removed, leaving little triangles of copper left behind.  Then the entire board is heated until the adhesive under the hatched areas melts and the triangles simply delaminate, leaving bare fiberglass.  Must take forever.  Still takes a very powerful laser and probably some very good optics.
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« Reply #13 on: June 02, 2010, 05:49:05 05:49 »

You will need at least an CO2 laser in order to cut copper, the lens and laser given by CD's, DVD's or BR's don't have enought power to cut metals.
However, the hard work for me is the mechanical parts...
I have the same idea with a CNC and i found some electronic burning laser at low cost (not CO2) at 1W that in theory can cut up to 5mm of plastic (with the correct focus lens). You must consider anyway the power losses given by heat and continue use time in the laser because it varies significatly with this two parameters.
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TomJackson69
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« Reply #14 on: June 07, 2010, 02:24:35 02:24 »

Shinta,

Can you provide link or more informations on how to buy the low cost laser with 1 watt power? Also any link for the lens? I am thinking about to use 4 or several 1 watt laser and focus them into one point to get more power.

Regards,

Tom
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Con Rong Chau Tien
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« Reply #15 on: June 19, 2010, 06:12:57 18:12 »

Hi all,

I am new to this forum. I have looked a bit to it's content --> seems impressive  Wink

Regarding the laser pcb design I have seen that a working technics could be to pre paint the coper side with black coating and then remove the painting with the laser.

Here are the links :
http://www.cnczone.com/forums/showthread.php?t=41222
http://blog.synthetos.com/laser-etched-pcbs-take-2/

To finish my introduction ...

I enjoy CNC and already did 2 :

the first one (cheap) : http://freedom2000.free.fr/CNC_index.html
the second one (much bigger) : http://www.usinages.com/ma-fraiseuse-v2-a-vos-critiques-svp-t8144-195.html


JP

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Shinta
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« Reply #16 on: September 08, 2010, 05:33:48 05:33 »

Shinta,

Can you provide link or more informations on how to buy the low cost laser with 1 watt power? Also any link for the lens? I am thinking about to use 4 or several 1 watt laser and focus them into one point to get more power.

Regards,

Tom


Sorry.... Please, check inside E-Bay like 1W cutting laser and you will found excellents products.

Smiley
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« Reply #17 on: September 09, 2010, 06:58:20 06:58 »

here is one method, but I hasn't try it.

http://www.instructables.com/id/Custom-PCB-Prototyping-using-a-Laser-Cutter/

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« Reply #18 on: September 09, 2010, 09:55:46 09:55 »


Thanks for the heads up Dreamcat!

The method illustrated is very smart.
You coat blank board using some paint, and you vaporize the paint on the area you wish to etch.
The left over are the paint coated tracks.

You would still use chemical etchant to etch the board but, the quality of image transfer is much better than any other method.

Smart!
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« Reply #19 on: September 10, 2010, 07:09:59 07:09 »

I think make solder mask will be easy with same method.

It only need small power laser-diode, not co2 laser. maybe the laser-diode in DVD burner is enough.

but now where can I buy this kind machine? Laser cutting machine in general is very expensive.

someone would like to design this machine? I know nothing about mechanical design
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« Reply #20 on: September 10, 2010, 09:02:25 09:02 »

Here's am easy way to do boards with a laser:  http://www.pcbfx.com/
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« Reply #21 on: September 10, 2010, 09:53:10 09:53 »

but now where can I buy this kind machine? Laser cutting machine in general is very expensive.

There are a few laser cutter on eBay that are about US$800 - not very expensive.
Just about the price of a good Office Laser Printer.
The problems with them are that they are too small for practical uses, and have weak laser (40W).

Visiting the Canton Fair this year, I see a few Laser cutter makers with 120W lasers for about $2000
Again a great deal cheaper than it was a few years ago.
They are much more useful than the puny 40W stuff.

Posted on: September 10, 2010, 09:44:36 09:44 - Automerged

Here's am easy way to do boards with a laser:  http://www.pcbfx.com/

Toner transfer is the easiest and most accessible method

Instead of using the expensive transfer paper, I have lately been using glossy paper brochures.
They are good down to TSSOP IC pack (0.25mm/0.25mm track)   -- Thanks to BBarney for suggesting this a while ago
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« Reply #22 on: September 10, 2010, 03:07:17 15:07 »

Toner transfer is what I have been using the methods of the past.
but it is not very stable, since It is related with quality of toner.

glossy paper? next time I will buy a little to try it, thank you .

$800 is about 5600yuan, it is a little expansive for me. but it is worth.....

buy or not? someone always said " the choice is a difficult problem" Smiley
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« Reply #23 on: September 11, 2010, 01:51:57 01:51 »

Dreamcat..

Glossy paper brochures are those cheap tabloid magazine paper.
You don't buy them, usually big company like walmart, Aldi, Tesco etc  send them to your home loaded with advertisements.
You also find them used for cheap tabloid magazines.

.. Well I guess some countries does things differently.


Ok, I'll try a better description:

some brochures/magazine are made of very thin paper.
They are very easily wetted and dissolved when soaked in water.

Usually they have glossy surface thus are good for our purposes,
due to the fact that the toner from laser printer will not "soak" into the fiber of the paper,
thus ensuring clean detachment of the paper.

After printing using laser printer or photocopier, the procedure is the same as in using other type papers.
The difference after ironing is you then soak the lot into warm water until the glossy paper fully wetted,
then you can "persuade" the left over off the PCB by gently rubbing them off with your finger.

Obviously you will be left with a mess of paper pulp to clean in your sink,
but this is definitely cheaper than paying $$ for commercial transfer paper.

------------
In regard to toner, there are a bunch of cheap SAMSUNG laser printers with "Toner saver" features on them.
I found that they are definitely the best to be used for this purposes.
Simply switch off the toner saving and use Blackest print.

--------------
You are talking in Yuan..  I believe that is Chinese currency.
Are you in China? if you are, you can buy them even cheaper directly from factories.
The local prices for similar stuff in China are much cheaper than the export quality stuff.

As I said above, the US$800 versions are too small for practical purposes. 
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« Reply #24 on: September 11, 2010, 06:02:18 06:02 »

I have recently been using the laser printer/toner method and then etching it.  I have very good success with lines to 10 mils and comparable spacings.  The thing is with this method you really need a laminator.  I tried the iron technique and it sucked big time and gave inconsistent results. The laminator removes the guesswork.

As far as etching the board, well I dont use the old style etching tank where you foam the etchant.  I simply take some ferric chloride and soak a sponge in a small amount (cap full is enough) and then I keep wiping the board with the sponge.  It perfectly etches a smallish board in less than 3 minutes.
I was astonished at this quite frankly because I had used the foam etchant spraying tank for about 20 years and it took so long that it undercut the tracks so I could not do tracks less than 20 mils

I find it hard to believe a powerful laser could be used because of the carbon the laser would leave.. just my two cents worth.

Dillon
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