[REQ] PCB by LASER

[masster]

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.

[carbontracks]

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.

[oldvan]

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.

[oldvan]

Milling or use a photoresist, expose the photoresist using the laser, then chemically etch.

[wild]

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... :-(

[carbontracks]

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.  

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... :-(

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.

[borberk]

LPFK PhotoLaser S produces PCB. In addition it needs air compressor-blower and ventilation. It's price is abt 75k€+5k€ for blower+...

[Ichan]

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

[oldvan]

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.

[sputnik]

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.

[carbontracks]

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.

[Ichan]

So how LPKF do it? The cuts looks clean.

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

-ichan

[carbontracks]

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.

[Shinta]

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.

[TomJackson69]

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

[freedom2000]

Hi all,

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

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

[Shinta]

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.

[DreamCat]

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

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

[Parmin]

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

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!

[DreamCat]

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

[solutions]

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

[Parmin]

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

[DreamCat]

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"

[Parmin]

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. 

[Dillon]

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

[Ichan]

Hi Dreamcat,

I have a method for transfering the toner to copper without using any heat, I use "pain relief rubbing oil" as in the picture attached - i believe you can find similar thing in your place. I use photoresist for making pcb now, but this is the way I always do in the past.

Basically it is a solvent to the toner but evaporate very slowly, maybe a mixture of mineral oil + a little turpentine oil will do but haven't tried it.

Here is the steps:
- moist the copper surface with the oil using your finger or tissue, do not put too much oil - just moist.
- lay down the paper with toner to the oiled copper surface carefully, make it flat.
- wet your finger with water and press the paper gently from the back little by little using your wet finger until all the paper looks "transparent"
- the toner will be stick to the copper, and the paper start to soak.
- depend on the paper used, remove it by using plenty of water.

And for the paper, you can make your own transfer paper by coating an ordinary "photocopy paper" with PVA (Poly Vinyl Alcohol) solution, also Dextrin coated paper will work too.

-ichan

[DreamCat]

I has been make 5mil width wire use toner paper some times. really!
but it depend on the quality of toner, and 5mil width copper is too easy peeling.

Dear Ichan , I will try to use lubricating oil do it next time.

[Ichan]

Hi Dreamcat you should try it, on my experience success rate is a lot better than ironing. Ironing method will depend very much on the cleanliness of the copper substrate and the flatness of the pcb + iron.

-ichan

[DreamCat]

I'm thinking which kind of solvent can dissolve the colloid of toner so that toner could be completely spalling.

[Ichan]

Just go to a grocery and buy some rubbing oil 

I'll ask someone here to make video of it, give me several days.

-ichan

[carbontracks]

If you have the money to shell out for a CNC laser setup, then you might as well get an ultraviolet exposure setup.  This is what we do at my work for quick prototypes.  You start out with copper board with photoresist already coating both sides (can be bought many places), then you make masks using overhead transparencies and a standard printer.  Put the masks over the copper board, then do a 40 second UV exposure.  Take it out and rinse it with dilute NaOH for a minute to remove the unexposed photoresist.  Then you're ready to etch with whatever method you want.  After etching, wash off the leftover photoresist with methanol.  When I do this the whole process generally takes about a half hour for a double sided board (drilling holes and vias is another story...).  I've gone down to 12mil traces comfortably with this method.  Could probably push it to 10mil, but I don't see the need.

Not sure what UV exposure tables cost new or surplus, but I can't imagine it being as much as a laser cutter.  And it would be much easier to DIY.

[sgoum]

I have made my own UV exposure table using 4 uv lamps like this http://www.xoxide.com/colcatblac.html and using an old scanner as a case. Its very cheap and works like a pro.

[Ichan]

Hi,

Here is the video of toner transfer without using any heat: http://ifile.it/jewx8ly/TonerTransfer.mp4 (2.31MB).

The video duration is about 1 minute in 4x real time speed, so the actual process is about 4 minutes not including the Ferric Chloride etching process.

Better and easier than ironing... 

-ichan

[DreamCat]

Thanks Ichan, it seems very nice. which kind paper were you used for it?

anyone know which other solvent can be used as alternative? I can't buy it.

[Parmin]

Ichan
That is the damnest easy technique!
Definitely worth a try!   I will go out and buy some of the oil thingy from nearby $2 shop NOW!
Thanks for sharing this!.

[iphone]

Hi Dreamcat,

 I use photoresist for making pcb now, but this is the way I always do in the past.

-ichan

What is the diffrent between those 2 (in term a result) ?

[Vague]

I have been using the laser transfer for a while now. I have found the best paper to use is the shiny paper left after you have removed sticky labels from a sheet of stick labels.
Once you have ironed it the paper just lifts off no need to soak. You can even use this more than once.  I think this might work really well with Ichans method, since the toner doesn't stick to the paper very firmly

Posted on: 01 October 2010, 10:09:31 - Automerged
I have just looked up the composition of rubbing oil. It consists of eucalyptus oil,  camphor, and methyl salicylate. I guess the main solvent is the eucalyptus oil

[Ichan]

Dreamcat, the paper used is home made Dextrin coated paper.

http://en.wikipedia.org/wiki/Dextrin

Mix Dextrin with water to make a viscous liquid (semi paste) then ask other people to screen print it into 80gr photocopy paper. PVA will work too but it tend to foamy when screen printed, maybe hand bar coater will work with PVA. Most commercial water based transfer paper is PVA coated paper.

What is the diffrent between those 2 (in term a result) ?

In term of result, photoresist will give the best accuracy and sharpest edge.
Toner transfer quality will be limited by the quality of the laser printer print out, while photoresist method need good quality masking film which make it difficult for DIY.

I guess the main solvent is the eucalyptus oil

Probably. I just buy a new one to get the packaging, here is the ingredient written:

- Menthol Crystals 20%
- Eucalyptus oil 15%
- Methyl Sallicylate 15%
- Camphor 5%
- Essential Oil 12%
- Base to 100%

Seeking the web using english keyword make me know that it is actually product of singapore:

http://www.axebrand.com.sg/product.html


-ichan

[Altair]

I originally started making my own printed circuit boards right out of High School in 1972. I used pre-stick pads and line tape applied to clear plastic film which was then used to make an Orange Color Key negative. A board was sprayed with photo-resist from GC Electronics, then KPR was used to develop the board after exposure from a 150 watt ultraviolet 'food warming' light. From there the board went into the plastic etch tank that was heated with a fish tank warmer.  Etching would usually take around 20 minutes. 

Fast forward about 38 years and I find myself setting-up a small circuit board manufacturing operation for prototyping control circuits for a Store Fixture Company I work for.  I heard they needed to fabricate a prototype circuit board in advance of producing 1000 store displays used to sell LED light strips.  Nobody in our company of 250 employees (other than me) had ever done anything like this before so I was nominated.  I actually expected that I could get us set-up within a couple of days but I soon found out that you can't easily get many of the essential materials anymore, such as Kodak Orange Color Key.  Google brought me most of the answers I needed so I was off and running. 

One very cool alternative to the standard etching tank that I found was the use of plastic Ziploc bags and a roller.  Here is where I found the source of this technique:
http://www.pulsarprofx.com/pcbfx/main_site/pages/tech_support/no_etching_tank/no_etching_tank.html

Pulsar's Technique #2: "Brayer" has proven to be the best alternative and produces absolutely no mess at all!  I had a little trouble finding the Brayer roller (locally) but I finally found one at an art supply store. By the way, despite what the Pulsar article says, you will NOT find the Brayer Roller at Michaels.  I purchased a couple of photographic chemical trays from a local photography supply company and cut a piece of 1/8" acrylic plastic to lay in the bottom of my new chemical tray.  The purpose of the plastic is to provide a completely flat surface in the bottom of the tray to use to support the circuit board inside of the bag.  These trays have deep channels molded into the bottom, which, if your circuit board is small, can allow the corners to dip down and potentially cut through the Ziploc bag(s).  I was able to etch a 2" x 3" double sided board in less that 3 minutes, using cold ferric chloride!  I have now etched 10 boards with the same original volume of acid and so far no sign of slowing down.  With this method, my small supply of acid will last FAR longer than when I used my old large tank.

[hunter07]

Hey,
Could you re upload the file(tonertransfer.mp4)
thank you..

[Ichan]

Unfortunately i don't have the file anymore, searched the hd and backup cd's - nothing found, i am sorry about that. Looks like i delete the entire video editing directory not long after i upload it.

Perhaps someone still have it?

-ichan

[blip]

Hi everybody.

I'd like to add some info to this topic. Here is a blog where I describe how I adapted a ShapeOko2 CNC to use a 0.5W 808nm laser diode (from EBay) and make PCBs. You may find some of the information useful.

http://gabuleu.blogspot.com

[Ichan]

How is the result of lasered painted pcb on your website etched? Does it etched good?

-ichan

[blip]

I haven't tried to etch yet. I'm still fine tuning everything, including the workflow from Eagle to GERBER to GCode. I'll post my results here. I'm also trying to find a cheap solution for a 5W laser, like the one from OptLaser that can be found here: http://optlasers.com/en/41-cnc-modules

[optikon]

I haven't tried to etch yet. I'm still fine tuning everything, including the workflow from Eagle to GERBER to GCode. I'll post my results here. I'm also trying to find a cheap solution for a 5W laser, like the one from OptLaser that can be found here: http://optlasers.com/en/41-cnc-modules

Surely with all that money invested you would have a goal or some estimate of performance vs low cost (professional) PCB fab these days.

[blip]

I've posted my first etching attempts to my blog:

http://gabuleu.blogspot.com

They were done with a solution of H202+white vinegar+kitchen salt described here:

http://www.instructables.com/id/Is-the-best-PCB-etchant-in-every-kitchen-/

Macroscopically they look good, but microscopically they still lack quality.

My goal is to be able to make prototypes easily and quickly at home. If possible, by using different materials and techniques. Maybe I'm spending too much money (less than 2kUSD) or time on that, but I believe the flexibility pays.

I have updated the blog with some videos and pictures.

I appreciate your feedback.

Best regards!

[solutions]

Etch with an isolation milling pattern is not a good idea

Why are you patterning with vector instead of raster?

[Ichan]

Lasering a paint coated pcb is my current method for a quick pcb prototyping, some things i found important:

- the paint must be very very dry, spray very thin paint 3 times, make sure the paint completely dry on each.
- sand the copper surface by a fine sand paper before painting (grit #800 or finer)
- lasered surface will have some paint residue left which can be difficult to be etched
- to remove the residue wet rub it with abrasive detergent like VIM or similar using finger or a hard sponge
- fresh warm ferric chloride is perfect as it doesn't generate bubbles while etching like the acid base etchant

Show your next experiment please.

I myself prefer vector isolation (2 or 3 vector overlap) than raster as it is much faster and cleaner edge, for generating isolation milling path i like to use Sprint Layout.

-ichan

[blip]

Hi! Thanks for your comments. I'll try to do a better spray painting. I was not investing too much in it because I was focusing my efforts on the laser etching. Now that it is done, I'll review the other steps.

I tried many ways of transferring the PCB pattern to GCODE. My first tries were to export a GERBER from Eagle and then transform it to PNG using Gerbv. Finally I would load the PNG to MeshCAM and generate de GCode with very well defined parameters. I was taking a long time and the process was confusing MeshCAM because of the PNG input. I was getting pixelated output, full of strange track borders.

Now I'm generating the insulation pattern using PCB-GCode, directly from Eagle. This is a ULP script that does a nice job, transforming a vector layout directly into GCode. This is the easiest process I found until now.

But I'm looking for a substrate that can be laser etched, so I can etch the tracks into it, drill the holes with the laser and, after that, deposit copper using simple chemical methods. If this works, the result will have the vias already covered with copper, dispensing other steps in the production. As a substrate, I was thinking of using wax, but I could find no wax that absorbs 808nm. Maybe with UV it is easier, but 150mW of UV does nothing to the substrates I tested.

I may buy and install a 5W laser head from OPTLasers. They have a nice product for 500 dollars, with analog modulation and emission in 445 nm. But I prefer to spend this money after I have tried all the cheaper options.

Thanks for your comments. This is a nice forum.

Posted on: December 29, 2015, 10:49:35 22:49 - Automerged
It could be also possible to etch the tracks on the paint using laser and deposit something over them to protect them from chemical etching. The next step would be to remove the paint from the rest of the board using solvent and insert it into a chemical etching bath. 

Anyway, the greatest prize for me would be to end the process with copper plated holes.

[Ichan]

I just see your youtube video, it is a very slow process.

What i use for this is a china made laser cutting machine with 80W glass tube, it can do isolation path vectors in 40 mm/s speed.

I ever tried lasering the pcb copper surface using 20W fiber laser, once it can go through it the underlying epoxy substrate charred badly.

What kind of laser source which is 5W you mentioned?

-ichan

[blip]

80W is a lot of power. Can it cut through the copper layer too?

Indeed mine is slow, but very cheap.

The 5W laser head can be found here: http://www.optlasers.com

I did not understand. Can you cut the epoxy layer with your 80W CO2 laser?

[Ichan]

No, 80W CO2 laser can not cut any metal.

CO2 laser for metal cutting application usually in KW range, 150W and above plus oxygen can cut trough thin steel sheet, but not other metal. To cut metal the trend now is using Fiber Laser, currently still too expensive - note that "fiber coupled laser" is not the same with "fiber laser".

80W CO2 can cut epoxy but not the glass fiber inside the pcb substrate.

That 5W optlaser is a blue laser diode module, for spending $500 i think better play with 35W CO2 glass tube - but you will have to rebuild your machine, look at HERE.

-ichan

[blip]

Thanks for the info. Many people may be interested in your experience and in these numbers. I was thinking of installing a CO2 laser in my CNC, but this info you gave me made me rethink.

I've just posted some results on using PCBGcode with Eagle and on finding a good focus position:

http://gabuleu.blogspot.fr

Your comments are welcome.

Posted on: January 01, 2016, 11:23:42 23:23 - Automerged
Which fiber they use to generate such power, do you know? I did my masters in optics. Fiber lasers can be built with the right fibres and the right pumping...

[Vineyards]

I was thinking of fitting my A4 size mini CNC with a laser head.
Are you painting a PCB with ink and etching that with a low power laser head? If that is the case:
1- What is a suitable wattage range?
2- How long does it take to finish a Eurocard PCB?
3- Do you need to use a coolant?
4- Are there any fumes or hazard risks involved?
Thanks in advance.

Posted on: January 02, 2016, 01:01:23 01:01 - Automerged

That 5W optlaser is a blue laser diode module, for spending $500 i think better play with 35W CO2 glass tube - but you will have to rebuild your machine, look at
-ichan

What about the costs of a compressor and a CO2 feeder?

[blip]

Vineyards:

Hi. I use a 0.5W 808nm laser diode. I bought the parts on EBay and assembled the rest myself. Earlier blog posts show parts list and some details.

The example board I showed on the blog takes around 15min to plot with the laser. I do not know about the Eurocard PCB. Mine is 35mm x 18mm approx.

I use no coolant. Maybe a small fan around would be nice. Nothing else.

You can see some smoke coming out of the paint where the laser hits. I do not believe it to be hazardous, but the room where the CNC is installed has a constant breeze flowing. I do not see any trouble.

Ichan:
About a CO2 laser tube, I have a question. When you install it on a CNC, do you use the collimated beam to cut or do you focus it with a lens in the end of the optical circuit?


Posted on: January 02, 2016, 02:59:53 02:59 - Automerged
PS: I tried to focus the laser beam on a PCB while it was being chemically etched. What I found? The spot where the light was focused remained clean, copper like. Everything around was coloured brown, green, etc, due to the reaction. Does the light inhibits salt formation on the focal spot?

[Ichan]

Glass tube is not ideal to be mounted on z axis of cnc router style mechanism because of:
- big size and heavy, 35 watt will have about 70cm length.
- glass is fragile
- need water cooling circulation
- high voltage about 18KV DC

There are samples on the internet people who mount the tube vertically on the Z axis (so no mirrors required), but the most common mechanism is light high speed X-Y gantry mechanism, Z axis usually not needed. The tube positioned outside of the mechanism where the laser beam delivered to the cutting point by several mirrors. The beam comes out the tube is in several mm diameter size, it will need to be focused by lens just before the cutting point.

What to buy for small glass tube laser system:
- laser tube + mounting bracket
- laser power supply
- 2 or 3 mirrors + mounting bracket
- focus lens + mounting bracket (laser head)
- small aquarium water pump + tubing
- optionally a small air compressor for air assist to cut thicker material

I saw all available on the site i gave the laser tube link before, i have no other intention but just use it as reference - i myself bought related things directly from china.

-ichan

[blip]

Ichan,

Glass may be transparent to IR light, but I know it absorbs UV. That may be why few Watts on UV wavelength may do a lot more damage to glass than many more Watts of IR.

[Ichan]

Hi Blip, i am seeking for UV laser source for some time - do you know one?

I believe LPKF pcb laser machine use UV laser.

-ichan

[blip]

Ichan, the highest power I could find for a NEW laser diode at 405nm on EBay was this:

http://www.ebay.com/itm/Sony-SLD3237VF-405nm-400mW-Violet-Laser-Diode-5-6mm-Brand-new-1-pcs-/231573723017?hash=item35eade9789:g:O9IAAOSwNSxVY8ec

There are some units available at 900mW, but they seem to have been taken from  other devices.

But if we go to a slightly longer wavelength, in the blue violet region, there are those 5W LDs at 445nm. I'll try to find the soda lime glass absorption spectrum at 445nm to compare it to 405nm.



Posted on: January 04, 2016, 01:12:24 01:12 - Automerged
Found this:

http://3dprinter.wdfiles.com/local--files/dlp-projectors-optics/Borofloat-vs-soda-glass_transmission.gif

It would be amazing if we could deliver power at wavelengths up to 320nm.

Posted on: January 04, 2016, 01:18:52 01:18 - Automerged
I could not find a borosilicate glass transmission/absorption spectrum over 5microns. The ones I found suggest that it is opaque above 5000nm, which means glass is absorbing all the light from your CO2 laser source.  In this case deep UV 300nm lasers will not do any better than the CO2 laser you've got.

So how does LPKF cuts the board? They use a pulsed source?

[blip]

You may like this:

http://www.rofin.com/en/markets/glass-industry/laser-cutting/

[vern]

cutting metal with a CO2 Laser is not easy, see attached absorbtion spectrum
Since a CO2 Laser is around 10um, most metals are highly reflective in that area. Because of the long wavelength the focus spot is also bigger than with shorter wavelength.
That is why laser cutting machines have a very high output in the kW range. They are used because they are relatively cheap, compared to Fiber or other lasers.
Fiber lasers are around 0,925um where the absorbtion of copper is a little better. But since the wavelength is 1/10th of CO2, the focus spot is also 10 times smaller, so the energy per area is a lot higher.
But below 500nm absorbtion of copper is very good, an UV Diode with several watts is a better solution than a high power CO2 laser.
(always wear safety goggles!)

[crunx]

My two cents:

- Using a relatively low power laser to "burn"/evaporate a resist may be a good idea, as such resist is basically just paint. And ordinary etching should be thereafter rather easy to control.

- Engraving the metal directly with a high power laser is NOT easy: First, you need a lot of power, and secondly, there is a high propability of burning/carbonizing the base material (such as epoxy/glass fiber in FR4). See below about my experiences:

In my current work location in a consulting company doing development work and prototyping, they have a big, heavy, and expensive laser system capable of cutting metal and also producing for example prototype flexible circuit boards. The first time I requested the proto-shop for a small flex board, they had to fine-tune and experiment a while before the copper was cleanly cut without burning the base material. So it was NOT easy even for a professional with a lot of experience, and a very expensive machinery! (And the result was not astonishingly clean-edged, but still useful for a not too demanding flexible board)

[Vineyards]

I tried to focus the laser beam on a PCB while it was being chemically etched. What I found? The spot where the light was focused remained clean, copper like. Everything around was coloured brown, green, etc, due to the reaction. Does the light inhibits salt formation on the focal spot?

In my opinion, the heated spot causes a constant water outflux preventing metal from contacting water and the chemicals dissolved in it. In other words there is a heat jacket and a positive pressure. The surrounding area is also heated more than the rest of the board. Heat accelerates reaction. One would expect the presence of a globular heat zone causing a roughly circular imprint on the plane (that is the PCB). Different colors you see are caused by a very complex chain of reactions between FeCl3 and the copper on the PCB whoch continues until all the Fe in the etchant is consumed after which point it becomes pretty useless. There are however a series of reactions involving chlorine, NaCl as well as other minerals and impurities in water.