LED PCB etcher
Conundrum, Thu Mar 26 2009, 10:22PMHi all..
Seems that lasers are sooo much hassle to use, so I came up with this. It uses an array of 0603 SMD UV LED's driven by a micro in Charlieplexing mode.
Here's a test with a single LED to prove that it works :)
image below is with 1, 2 and 5 seconds exposure at 3mm.
-A
Re: LED PCB etcher
3l3ctrici7y, Fri Mar 27 2009, 03:54AM
I get it; the top pic is the LED on the board, the middle pic is the let led, and the final pic is the 1, 2, 5 second exposures. The high density of the intended array is for illuminating a board that is coated with photo resist, masked by the pcb artwork....
How am I doing... oh...
no, wait.. were you going to literally "CNC" etch the board by selectively exposing the photoresist with the multiplexed leds?
Perhaps get a uv laser diode, and appropriateeba focusing lens, and drag it around the board to draw your pattern. Ah, here we go... Something like this in a 2 axis (at least) cnc might get the job done... ebay
But I digress.. what exactly are you doing?
3l3ctrici7y, Fri Mar 27 2009, 03:54AM
I get it; the top pic is the LED on the board, the middle pic is the let led, and the final pic is the 1, 2, 5 second exposures. The high density of the intended array is for illuminating a board that is coated with photo resist, masked by the pcb artwork....
How am I doing... oh...
no, wait.. were you going to literally "CNC" etch the board by selectively exposing the photoresist with the multiplexed leds?
Perhaps get a uv laser diode, and appropriateeba focusing lens, and drag it around the board to draw your pattern. Ah, here we go... Something like this in a 2 axis (at least) cnc might get the job done... ebay
But I digress.. what exactly are you doing?
Re: LED PCB etcher
Hazmatt_(The Underdog), Fri Mar 27 2009, 07:26AM
Hate to be unimaginative, but I just use 10 min of free sunlight.
Hazmatt_(The Underdog), Fri Mar 27 2009, 07:26AM
Hate to be unimaginative, but I just use 10 min of free sunlight.
Re: LED PCB etcher
..., Fri Mar 27 2009, 11:23PM
He is trying to etch boards without makign a mask, thus the need for many small LEDS
he tried using a laser to expose it in an earlier thread, but didn't have much luck.
Although except for maybe etching the simplest of boards, it seems the resolution of this will be too low.
Heres my idea, take a black/white LCD panel and put a backlight of UV leds behind it. There will probably be a ton of loss from the uv being absorbed in the screen (but i wouldn't expect a whole ton, glass is pretty transparent under 380nm and plastic goes to about 350nm). Then just bring up a picture of the board you want and viola
..., Fri Mar 27 2009, 11:23PM
He is trying to etch boards without makign a mask, thus the need for many small LEDS
he tried using a laser to expose it in an earlier thread, but didn't have much luck.
Although except for maybe etching the simplest of boards, it seems the resolution of this will be too low.
Heres my idea, take a black/white LCD panel and put a backlight of UV leds behind it. There will probably be a ton of loss from the uv being absorbed in the screen (but i wouldn't expect a whole ton, glass is pretty transparent under 380nm and plastic goes to about 350nm). Then just bring up a picture of the board you want and viola
Re: LED PCB etcher
Conundrum, Sat Mar 28 2009, 10:52AM
hmm.... i did try that with a damaged single line HD44780 panel but unfortunately the panel broke during removal of the backplate.
It might work, i've confirmed some light gets through. My latest idea is using a spare PCMCIA laptop edge connector (which has virtually identical pin spacing to 0603) and a spare LCD panel's STaB connector as a ground plane and interconnect. Plan is to use Charlieplexing (common +V and Gnd) to minimise the number of interconnects to sensible levels.
Am up to 12 LED's soldered with no defects... :) pics soon.
Will need to use some sort of mask to prevent spurious PCB exposure, have an idea to use a sheet of acetate with pinholes at the correct spacing.
-A
Conundrum, Sat Mar 28 2009, 10:52AM
hmm.... i did try that with a damaged single line HD44780 panel but unfortunately the panel broke during removal of the backplate.
It might work, i've confirmed some light gets through. My latest idea is using a spare PCMCIA laptop edge connector (which has virtually identical pin spacing to 0603) and a spare LCD panel's STaB connector as a ground plane and interconnect. Plan is to use Charlieplexing (common +V and Gnd) to minimise the number of interconnects to sensible levels.
Am up to 12 LED's soldered with no defects... :) pics soon.
Will need to use some sort of mask to prevent spurious PCB exposure, have an idea to use a sheet of acetate with pinholes at the correct spacing.
-A
Re: LED PCB etcher
Netzpfuscher, Sat Mar 28 2009, 06:06PM
you need a blue-ray diode and mount it on a plotter ;)
This is my project:
http://de.youtube.com/watch?v=JG5qUhn9sSM&feature=channel_page
Netzpfuscher, Sat Mar 28 2009, 06:06PM
you need a blue-ray diode and mount it on a plotter ;)
This is my project:
http://de.youtube.com/watch?v=JG5qUhn9sSM&feature=channel_page
Re: LED PCB etcher
Conundrum, Sat Mar 28 2009, 07:21PM
hmm, thanks for that, i might try it.
in the meantime i've made progress on the LED PCB..
-a
Conundrum, Sat Mar 28 2009, 07:21PM
hmm, thanks for that, i might try it.
in the meantime i've made progress on the LED PCB..
-a
Re: LED PCB etcher
cjk2, Sat Mar 28 2009, 08:54PM
@ Netzpfuscher
That is amazing! how thin can you get the traces?
cjk2, Sat Mar 28 2009, 08:54PM
@ Netzpfuscher
That is amazing! how thin can you get the traces?
Re: LED PCB etcher
Conundrum, Sat Mar 28 2009, 10:47PM
Not exactly sure, estimate around 0.2mm.
i can improve on that, by using a shadowmask though.
the plan is to use the prototype to make a pcb for the better version...
Conundrum, Sat Mar 28 2009, 10:47PM
Not exactly sure, estimate around 0.2mm.
i can improve on that, by using a shadowmask though.
the plan is to use the prototype to make a pcb for the better version...
Re: LED PCB etcher
Netzpfuscher, Sun Mar 29 2009, 02:15PM
@cjk2
It depends on the setting of the laser-focus, from 0.05mm to 1mm but the mecanical resolution of the plotter is limited to 0,1mm. the best results are with 0,15mm laser and ~30mm/s pen speed.
Netzpfuscher, Sun Mar 29 2009, 02:15PM
@cjk2
It depends on the setting of the laser-focus, from 0.05mm to 1mm but the mecanical resolution of the plotter is limited to 0,1mm. the best results are with 0,15mm laser and ~30mm/s pen speed.
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