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HD-DVD PCB maker

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Conundrum

Sat Jun 21 2008, 06:11AM

Registered Member #96
Joined: Thu Feb 09 2006, 11:37AM
Location: "Somewhere in Guernsey"
Posts: 985

Hi all.

I had a discussion with someone a while back about whether the NUV light from a Blu-ray or HD-DVD laser diode would be powerful enough to "burn" the photosensitive coating on a piece of FR-4 PCB.

It works!!!! just tried it now and I can see patches of the green photoresist have visibly changed reflectivity where I "drew" on them with my focussed HD-DVD laser running at about 37.5mA (parallel 2K4 resistor means I am actually feeding it 39mA) with about a 0.2 second exposure.

Setup is the diode with the Blu-ray lens placed directly on top with about a 0.1mm gap, encased in some low melting point alloy with connections and resistor shielded by epoxy.
Currently running from LM317T with 39 ohm and 180 ohms in parallel from Adj to Out.
(memo to self:- check output current BEFORE hooking up diode!!)

Next step will be to set up a modified "print" head using a stepper and board feeder.

I would expect a Blu-ray laser to work more effectively however the one I removed from the broken PS3 laser module was a lot more sensitive than expected and suffered COD during testing (and also had pre-existing damage showing up as "lines" on the uncollimated output.

This laser was removed from a surplus HD-DVD Xbox 360 drive, which there seem to be quite a few of (I wonder why haha) and these are the cheapest source other than PS3 lasers. I got mine for £32 on Ebay with mains adaptor and remote, plus you can use the gutted drive to play DVDs as the red laser diode is separate from the HD diode.

regards, -Ae

Smiley faces on the sun... ???!!!!

Finn Hammer

Sat Jun 21 2008, 09:55AM

Registered Member #205
Joined: Sat Feb 18 2006, 05:59AM
Location: Hobro, Denmark
Posts: 403

Conundrum wrote ...

Next step will be to set up a modified "print" head using a stepper and board feeder.

This could become something big, but wouldn`t the next logical step be to dump the PCB in drain cleaner to see if it has developed at all?

Chers, Finn Hammer

DaJJHman

Sat Jun 21 2008, 11:05AM

Registered Member #902
Joined: Sun Jul 15 2007, 03:17PM
Location: North Texas
Posts: 600

very good idea, as those diodes emit quite a bit of UV... I would love to see a full homemade PCB machine... I am sure this would be a must try project...

"I do not know with what weapons WWIII will be fought with, but I do know what will be used in WWIV: Sticks and Stones!"---- Albert Einstein.youtube website ---callsign KE5TUZ, Amateur Extra

...

Sat Jun 21 2008, 12:14PM

Registered Member #56
Joined: Wed Feb 08 2006, 11:02PM
Location: Southern Califorina, USA
Posts: 2118

I would try looking for bare diodes on ebay, I got a 130mw 405nm diode for about $60 (and there are still some left for sale)

In any case, I hope you can make this idea work!

check out my website!

Conundrum

Sat Jun 21 2008, 02:55PM

Registered Member #96
Joined: Thu Feb 09 2006, 11:37AM
Location: "Somewhere in Guernsey"
Posts: 985

Hmm. I assume that by "drain cleaner" you mean something based on sodium hydroxide.

Catch is, I can't get that over here. I can get washing soda or caustic soda, but a solution of the former did nothing.

Tried Jessops but no go (though they did have some acetic acid "stop" bath bottles)

Any ideas?
BTW it looks like I may be getting another BLU-ray diode to play with as this new one still won't read disks due to some sort of alignment issue. I am loathe to send it back so as soon as the new deck arrives this one is getting modded :)

Smiley faces on the sun... ???!!!!

Finn Hammer

Sat Jun 21 2008, 04:58PM

Registered Member #205
Joined: Sat Feb 18 2006, 05:59AM
Location: Hobro, Denmark
Posts: 403

Conundrum wrote ...

Hmm. I assume that by "drain cleaner" you mean something based on sodium hydroxide.

That`s right, but the main point was that I thought it would be a good idea to develop this first test piece
before building a whole cnc machine.

Cheers, Finn Hammer

HFsstc-freak

Sun Jun 22 2008, 04:26AM

Registered Member #941
Joined: Sun Aug 05 2007, 05:09AM
Location:
Posts: 289

Why not just mod a laser printer as in removing the drum and redo the mechanics to accomodate a flat board, then replace the laser with one with the right wavelenght ?

Conundrum

Sun Jun 22 2008, 05:45AM

Registered Member #96
Joined: Thu Feb 09 2006, 11:37AM
Location: "Somewhere in Guernsey"
Posts: 985

Interesting idea, but you'd have to replace the optics as the blue diode is reallly hard to focus. I had to work for nearly an hour making incremental adjustments on the epoxy lens mount just to get a reasonably good spot geometry.

OTOH, if you gut a Bluray module you can remove that little microscopic circular grating under the lens, put this above the laser diode (if need be leave the lens intact but trim its mountings) and the resultant beam should be a lot "cleaner" but you'll lose some output.

I set the focus for about 8cm but obviously this can be shortened.

see here

This guy is selling brand new Blu-ray diodes
hope this helps, -A

Smiley faces on the sun... ???!!!!

...

Sun Jun 22 2008, 01:19PM

Registered Member #56
Joined: Wed Feb 08 2006, 11:02PM
Location: Southern Califorina, USA
Posts: 2118

but for the same price this guy is selling 150mw ones

BTW, for focusing I have had very good luck using the cheepo diode colminators (like

) you just unscrew the end a little to correct the focus

check out my website!

GeordieBoy

Sun Jun 22 2008, 02:53PM

Registered Member #1232
Joined: Wed Jan 16 2008, 04:53PM
Location: Doon tha Toon!
Posts: 674

Wouldn't a focused laser diode write in such thin lines (like 10 micron spot size or smaller?) that exposing photoresist on a PCB using a focused laser diode would take forever?

"NEVER EVER mess with a PCB jumper you don't understand, even if it's labelled 'Sex and Free Beer'"

EEYORE

Sun Jun 22 2008, 10:25PM

Registered Member #99
Joined: Thu Feb 09 2006, 12:10PM
Location:
Posts: 579

GeordieBoy wrote ...

Wouldn't a focused laser diode write in such thin lines (like 10 micron spot size or smaller?) that exposing photoresist on a PCB using a focused laser diode would take forever?

You could just bring the laser out of focus a little...Right?
Matt

GeordieBoy

Mon Jun 23 2008, 04:57AM

Registered Member #1232
Joined: Wed Jan 16 2008, 04:53PM
Location: Doon tha Toon!
Posts: 674

> You could just bring the laser out of focus a little...Right?

...but that will presumably decrease the power density meaning it will take much longer to expose?

"NEVER EVER mess with a PCB jumper you don't understand, even if it's labelled 'Sex and Free Beer'"

Conundrum

Mon Jun 23 2008, 02:06PM

Registered Member #96
Joined: Thu Feb 09 2006, 11:37AM
Location: "Somewhere in Guernsey"
Posts: 985

will have to investigate this. I did obtain some Na(OH)2 so can now develop the PCB. Unfortunately it looks like one of my chemicals mullered up the photoresist but thats no biggie as there's still enough to expose it again.

The power density is high enough that at 0.1mm focus it will still expose a fairly large area (0.3mm diameter when I tried it) so ironically the problem is going to be avoiding over exposure.

Update:- It works, just finished the (slow as molasses) etching now. See below for my ingenious Macgyver-style PCB etch heater..

Update 2:- Have ordered some spray-on PCB photoreactive coating, will update you as to how well this works with the same diode and/or UV LED array (30s exposure time)

-A
"Bother" said Pooh, as the warp nacelle fell off...

Smiley faces on the sun... ???!!!!

Conundrum

Tue Jul 08 2008, 01:26PM

Registered Member #96
Joined: Thu Feb 09 2006, 11:37AM
Location: "Somewhere in Guernsey"
Posts: 985

Update:- I discovered a slight problem with the Ebay purchased photosensitive material as it is the "blue" type inferior dye. It does work but is about an order of magnitude less sensitive.

I suspect that rapidly spinning the PCB during spraying will get around this problem (google "spin coating") and will try this next. In the meantime, perhaps an additional modification would be to irradiate the vicinity of the focus area with UV light from conventional NUV LED's to presensitise the PCB and let the laser do its work more quickly.

Side effects would include a chance of burn-through, but the increase in throughput would be worth it.

Please advise. I can't believe I'm the only person to be working on this...
regards, A

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Carbon_Rod

Wed Jul 09 2008, 06:05PM

Registered Member #65
Joined: Thu Feb 09 2006, 12:43AM
Location:
Posts: 504

For thin coats slow dry at a 60' angle.

note if any droplets appear there was too much emulsion applied.

Photo plotters were around for many years, but became much less popular in the late 90's.

"As you go through life, make this your goal: Keep your eye on the doughnut and not on the hole." (?)

aonomus

Wed Jul 09 2008, 08:43PM

Registered Member #1497
Joined: Thu May 22 2008, 12:24AM
Location: Toronto, Ontario, Canada
Posts: 771

You got posted on Hack A Day I think....

My blog:

- mostly about electronics and other stuff, mostly to waste time.

Conundrum

Sun Aug 10 2008, 08:38AM

Registered Member #96
Joined: Thu Feb 09 2006, 11:37AM
Location: "Somewhere in Guernsey"
Posts: 985

*This* is what happens when you use a proper 150mW Blu-ray burner diode instead of a wimpy HD-DVD read laser.

Obviously you ABSOLUTELY MUST USE safety goggles!!!!!!!! I used one of those gas welding goggles which does work but would strongly recommend the correct equipment.

(end of safety rant)

Diode is being run at approx. 95.6mA which is well within its safe limits. The seller says he has run them up to 120mA but for test purposes this is fine.

Safety circuits include:- parallel 1K resistor and 0.1uF capacitor, input smoothing and zener, so that in the unlikely event of a regulator problem or other anomaly the diode should survive.

As you can see, I've encased the diode in low melt 95c alloy and mounted the lens the same way, this is not ideal but it does at least allow reasonable run times without risking thermal runaway.
I estimate heat being generated is around 0.7W at 95mA
The assembly is mounted on a surplus heat pipe from a broken PC motherboard, and fixed to the HP LJ module with epoxy.

I had to remove the two beam shaping lenses as it turned out they defocussed and absorbed the beam too much, without them the dot looks much sharper and the beam is nice and round with few artifacts.

UPDATE 2:- Spin coating the PCB with resist works well, you need to do this in low light however or your hard work will be wasted. I
used a modified PC PSU fan motor and glued the PCB to it, then started from the inside edge and worked outwards at about 1cm/sec then let it dry. The results speak for themselves :)

Here are some pics.

Smiley faces on the sun... ???!!!!

Conundrum

Fri Jan 02 2009, 11:06AM

Registered Member #96
Joined: Thu Feb 09 2006, 11:37AM
Location: "Somewhere in Guernsey"
Posts: 985

Hi..

I have mounted the scan module onto a spare scanner cover, so it now has stepper and CDROM drives as the X and Y grids.

The scanning area is approx 2" across (with modified laptop drive unit) and it also etches through the glass thereby preventing the annoying PCB alignment problems.

Observe.

-A

Smiley faces on the sun... ???!!!!

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