Laser "projector" for PCB mask creation

[VDX]

Now that sounds like fun! That must have cost a small fortune.

... the OEM price was something like 30-40k€ then, but got it in exchange for some spare parts for PCB-generating and microtech I had in my basement.

I'm in some different groups, where we're exchanging spare tools and bits someone has sitting around ;-)

Most of my 'more valuable' parts were sourced for project developments I've made from 1990 on --- and they often remained after the project was finished as 'sold prototypes' ... and I've got them for free or had built them on my own for the special project - for example a microassembly stage with nano-XYZ-stage, gripper and stereo-cams which I've made by 'refurbishing' a SMT-pick-n-placer (see attached image)

Others, like my CNC-mill, were bought for cheap (300€) as scrap glue-dispenser from a customer of Isel and then reworked/refurbished by me to a working mill ...

I've got recently an older dental-scanner and all the inner parts of a second for testing it's usability or for reworking it to something usefull --- so some more fun ahead ;-)

Viktor

[macona]

I know what you mean, I get a lot of my stuff the same way. The two DPSS lasers I have were something like $50k new. I traded time for them. I did swapping for my CNC mill and for a whole lot of other stuff.

Looks like that laser could be really useful!

[VDX]

... my greatest problem is lack of spare time :-/

Have all the guts of an old Stereolitho-3D-printer from 3DS without the (then used but outgassed) 30mW-HeCD-laser ... but here I've made successfull collimation tests with a BluRay-diode with 405nm@200mW and a blue diode with 445nm@1W, what's more than enough power to 3D-print or even micro-material-processinq! As the optics and mirrors aren' t coated, it could be even possible to use the 1070nm@50W fiberlaser with the scanner and optics ...

Another actual project is modifying DLP-beamers for use with the 405nm-diode or with a TAE-laser pulsing with 30Hz, 371nm@400kW and 200ps pulse-duration ... maybe something usable for microetching?

And some old projects around 3D-printing/rapid-prototyping with higher accuracies than common - laser-spots <10µ with the IR-fiberlaser, or refocussing the UV-pulse-laser over the 'naked' DLP/DMD-chip into an 'image' of some mm size ...

Viktor

[shrad]

VDX, was this a liconix HeCd laser? I'm looking for a dual cathode supply from liconix for tubes like the 4030, desperately

[VDX]

.. don't know it - a friend got two of this printers with removed lasers and I've grabbed only the transportable essential parts - attached the complete part before disarming ...

[macona]

Neat. I have been thinking of using my laser cutter to try stereolithography. I will have to work top-down like a traditional STL machine which means I need more expensive resin. Of course I think 6 watts average might be a bit overkill:

[Orum]

I say ditch the idea of using a laser diode, they suck for this kind of application. Get a cheap chinese CO2 tube and power supply and build a machine around that.

I don't want to use CO2 for numerous reasons, but mainly safety. In addition I imagine it's harder to focus, and it just provides more power than I need. I'm sure they're useful if I wanted to driectly burn the copper off, but I'd rather mask with paint and then etch.

This is my solution when I need boards: http://oshpark.com The boards are incredible. Made in the USA, double layer, gold plates, purple conformal, silkscreen for both sides. $5 a square inch and you get three boards for that price.

Yeah, I use Advanced Circuits when I need multiple copies. The purpose of building this was two-fold; to reduce cost and latency when I'm making a one-off board, and more importantly, to reduce cost and especially latency between when I finish designing a board and when I can actually test a prototype. Designing circuits is like programming or anything else of sufficient complexity--put it down for too long and it takes longer to get going when you start working on it again.

I've been looking at the Cambridge Tech galvos, and while they're pricy they seem to be designed for my application unlike many of the alternatives. The only problem is, I can't find much documentation on them. Many of them come with the driving boards, but how do I interface with it? It looks like it has some proprietary (or perhaps just unknown to me) connector. Their website seems to be dedicated to newer hardware, and it's hard to find out much about the older stuff that pops up on eBay.

[macona]

I don't want to use CO2 for numerous reasons, but mainly safety. In addition I imagine it's harder to focus, and it just provides more power than I need. I'm sure they're useful if I wanted to driectly burn the copper off, but I'd rather mask with paint and then etch.


Yeah, I use Advanced Circuits when I need multiple copies. The purpose of building this was two-fold; to reduce cost and latency when I'm making a one-off board, and more importantly, to reduce cost and especially latency between when I finish designing a board and when I can actually test a prototype. Designing circuits is like programming or anything else of sufficient complexity--put it down for too long and it takes longer to get going when you start working on it again.

I've been looking at the Cambridge Tech galvos, and while they're pricy they seem to be designed for my application unlike many of the alternatives. The only problem is, I can't find much documentation on them. Many of them come with the driving boards, but how do I interface with it? It looks like it has some proprietary (or perhaps just unknown to me) connector. Their website seems to be dedicated to newer hardware, and it's hard to find out much about the older stuff that pops up on eBay.

I would say CO2 is safer than anything else. Like I said you can use just about anything to shield from it. A generic face mask or safety goggles are all that is needed for eye protection. Also it is virtually impossible to get retinal eye damage for a CO2, the wavelength can not penetrate into your eye, think of the beam as a beam of heat, not light.

You state you want a window on the machine, this is pretty much impossible on a visible laser with most standard materials. You would have to have a window that it either made from a plastic specifically formulated for the wavelength you are using or coated to filter it out.

CO2 is very easy to focus. Even the cheap chinese tubes had decent beam quality and make a nice small spot. Typical kerf (Line width) on a co2 laser cutter is about .002". A simple GaAs plano-convex lens is all that is used to focus. There are chinese made scanlenses for CO2 on ebay too. A diode is just going to have a crummy beam.

We had a 45 watt epilog where I was working and there were a couple guys doing the spray paint resist technique with the laser cutter. The power definitely came in handy to make sure you got a clean cut in the paint. It is very difficult to cut copper with a CO2 laser since it reflects so much of the light. Heck, they make mirrors for CO2 lasers from polished copper.

On the other hand I can burn holes in copper with my 532nm laser since it has a shorter wavelength that is absorbed by it.

Which CT galvos are you looking at? The standard CT galvo will have a 9 pin D connector on it. There are some custom connectored CT galvos that were made custom for ESI that use a 9 pin D for the coil and a 9 pin micro D for the feedback. ESI uses a separate control box that drove external servo amps to drive the galvos and the box itself closed the loop.

Typically most galvo drivers use an analog interface, either +/-5v or +/-10v. Voltage is deflection and polarity is direction. There are a few different controllers out there. CTI makes one and I have seen them at $1k on ebay. There is a chinese company that makes a board called the ETH6608, it is a standalone ethernet board that will control two galvos. Comes with software to interface with it for $650. You can also use the Etherdream with the http://www.beamconstruct.com software, though the support is discontinued and no new features will be added for it in future revisions.

There are some scanner drivers that are digital, those need one of ScanLabs RTC boards, they sell at well over 1k on ebay.

Have you though about just doing isolation routing with a dremel/rotary spindle mounted on a cnc x/y stage? That's what a lot of the in-house prototype machines do.

[mixedgas]

Orum, I have a lot of the older Cambridge documentation. If you have the actual article in hand, and give them the serial numbers, support usually flows.
Support will be in the form of hookup data and the tuning/testing manual. Manuals are usually about 20-30 pages and are very intensive/ hard core. Once in a while schematics do come, but not often. Once in a while something shows up on Ebay that they will not support as its a custom driver. However you will find much data in the legacy portion of their website.

Galvo amps are not hard to hook up, you just start at the power output stage and work back.

If your a beginner, buy the whole set, amps and galvos. Building your own galvo amp has some interesting pitfalls. That one I linked down below for 125$ will not be hard to reverse engineer the hook-ups. Laser show guys use high speed galvos, and that set is a high precision positioning set, not known for its speed. That is why its there cheap, the majority of PLers would thumb their noses at a 4K PPS scanner vs a 30K pps scanner. Its perfect for you, its accurate. Odds are good it will have a "position valid" output as well, telling you when you can fire.


Steve

[Orum]

I would say CO2 is safer than anything else. Like I said you can use just about anything to shield from it. A generic face mask or safety goggles are all that is needed for eye protection. Also it is virtually impossible to get retinal eye damage for a CO2, the wavelength can not penetrate into your eye, think of the beam as a beam of heat, not light.

Well, that's precisely my worry--I can't see it, and at >= 200mW even if it doesn't penetrate the eye it could burn/ignite things without me realizing.

You state you want a window on the machine, this is pretty much impossible on a visible laser with most standard materials. You would have to have a window that it either made from a plastic specifically formulated for the wavelength you are using or coated to filter it out.

I was planning on getting a window specific to the wavelength of the laser I buy. Problem is, these windows are hard to find, and typically for longer (IR) wavelengths. When I do find them for visible lasers, they're fairly pricy. But I haven't looked as much for these as I have at the other components yet.

A diode is just going to have a crummy beam.

Yeah, I realize they're a bit of a compromise. The smallest etched areas I get down to are TQFP/LQFP packages, with a spacing between pads of ~0.24mm. I think that will be achievable with a diode laser, but if it doesn't work out, they're not that expensive. I'm sure I'll find other uses for a high power diode laser elsewhere.

Which CT galvos are you looking at? The standard CT galvo will have a 9 pin D connector on it.

Really anything that's accurate and in my price range (< $200 USD for a single galvo + amp), but mostly 6450s or 6860s as Steve recommended. While the galvo itself has a DB9, the amp they're sold with has the odd connector (bottom center of this auction's image. It also has a white wire pair coming off--is that for the analog input? If so, that would be a lot easier to use, but I'm still curious what the other plug is for. While digital galvos are nice as you said the price rules them out.

Have you though about just doing isolation routing with a dremel/rotary spindle mounted on a cnc x/y stage? That's what a lot of the in-house prototype machines do.

Definitely. However, hysteresis--I know you called it backlash, but I would define hysteresis as the property of a system's state being dependent on the previous (historical) states or knowledge of the internal state, and backlash as the specific cause of the majority of that hysteresis in this case--concerns me, especially when you have physical contact between a dremel bit and the board. The drill has to be very securely mounted, as does the copper blank. Lastly, while it lets you skip the chemical etching, it's a double edged sword; there's no way to proof your copper blank before you do something irrevocable to it.

If your a beginner, buy the whole set, amps and galvos. Building your own galvo amp has some interesting pitfalls. That one I linked down below for 125$ will not be hard to reverse engineer the hook-ups.

Oh yeah, definitely looking for the galvo & amp package. Some people go all out and even build their own galvos as well, but that's well beyond my ability for the accuracy I need, and just isn't practical.

I finally found the "Product manual archive" on their site, which I had glossed over before.