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DIY double sided 60W LED UV radiation unit with vacuum pump

Posted on Friday, June 26th, 2015 in DIY, LEDs by DP

800px-UVBoxOpen

Kurt Skauen has been working on a DIY 1188 LED dual sided UV radiation unit:

The UV exposure unit is controlled by an ATmega328P microcontroller and have the following features:

  • Single and double sided exposure. Each side radiated by a 594LEDs / 30W UV LED panel (The unit has a total of 1188 LEDs providing 60W of LED light)
  • The light panels can be calibrated to give even exposure on both sides
  • Built-in vacuum pump for laminating artwork and copper-clad

*The user can define 2-18 speed steps for the vacuum pump

*The vacuum pump can be set to automatically turn off a specified time after the radiation finish

  • Advanced programmable timer / power control for the light panels with 8 persistent presets

Project details at Kavionic blog.

 

  • Each of the presets can in addition be backed up to a “hidden” location and later restored
  • Audible alarm when radiation is complete
  • User input through a rotary knob that also act like a push button plus 15 standalone push buttons
  • User feedback through a 20×4 character backlit LCD display with adjustable backlight and contrast plus a piezo beeper
  • Tracking of runtime. The total on time is tracked. And the runtime of the two light panels and the vacuum pump are tracked with two values each. The absolute time running and the time scaled by the power/speed they where running at
  • Wear balancing of the EEPROM. Some values in the EEPROM is updated fairly often. Like the currently selected preset. And the runtime counters. So each of those values have multiple locations allocated for them in the EEPROM and new values are written to a new location each time until all slots for the value has been used. Then it will start over. This ensures that the guaranteed 100.000 erase/write cycles will last as long as possible

 

This entry was posted on Friday, June 26th, 2015 at 1:14 pm and is filed under DIY, LEDs. You can follow any responses to this entry through the RSS 2.0 feed. You can skip to the end and leave a response. Pinging is currently not allowed.

10 Responses to “DIY double sided 60W LED UV radiation unit with vacuum pump”

  1. Ross Potts says:

    I love seeing these. I think I could throw one of these together before I could finish my reflow oven.

  2. James says:

    Gah, so many LEDs. Having built a few UV boxes in the past, using standard 5mm leds is for chumps, believe me, I was one.

    You have to get them straight, you have to solder them all, you have to inspect them all and replace any ones which are sub-par, you have to balance number of LEDs with distance to the artwork, and even then you’ll get hot-spots… it’s very tedious.

    My latest box uses quite simply eight 1W UV leds (single sided box), they are only a couple bucks a pop, they have a wide viewing angle, arranged in a 3 – 2 – 3 pattern (star type mounting plates stuck on metal strips for heatsinking) so that they provide a uniform coverage, then used a couple diffuser layers (really, all this collimation stuff is pointless, just diffuse it, it really makes so little difference for home purposes).

    So much easier, SO MUCH EASIER than soldering hundreds of LEDs and getting them all perfectly straight and even.

  3. Kurt says:

    I guess you didn’t read the build log :-)

    I did not solder a single LED for this project. I wanted it to be as physically small as possible, and give as high definition as possible. So I opted for many LEDs and no diffuser. It is a total of ~9cm tall for dual sided exposure, and I have done 6-mil traces with 5-mil spacing on it.

    What is the physical size of the eight LED box? And what is the finest traces you have/can make with it? I must admit I have not done any scientific tests to verify that adding a diffuser would indeed cause any problems. But with very fine traces you really want to keep the “light undercut” to a minimum so the diffuser would worry me.

    • James says:

      Oh I didn’t notice you were using strip, thought it was 5mm leds from the photo. I also considered using tape, however a couple of reasons stopped me.

      1. the spacing on the tape available wasn’t very nice at the time I looked at it
      2. potential reliability/servicing issues, replacing a duff led would be annoying

      Anyway to your question, I have my leds placed 20cm-ish below the platen, however there are effectively 3 diffusers also in order to produce a perfectly (to the eye) flat light coverage without high spots. I also have a couple watts of white led in there for light-box mode (very useful to have these for checking art for toner flaws, the bed for dust, and etched pcb for shorts :-)

      All the diffusers are made from kitchen cutting sheets I found at a dollar type store, 0.4mm thick diffuse plastic. The 1st and 2nd diffuser are stuck on each side of a pane of glass set at the mid point between the lights and platen, the 3rd diffuser is stuck to the bottom of the platen.

      Exposure to dry film negative in my box is 2m40s followed by another 2m40s cure after development.

      With this arrangement I can achieve 8/8 if I really want to, but put simply, I seldom really want to, for home etching, I see little point in making it more challenging.

      • James says:

        I should also add, I don’t use a vac pulldown. Simple mechanical pressure only by way of velcro straps to cinch down the lid with some spongy bath mat sitting on top of the PCB under the lid to even the pressure out. My artwork is printed on 120gsm tracing paper.

  4. Ross Potts says:

    Gsm? Grams per square meter? I dint know that term…

    • James says:

      Yes grams per square meter is how you measure paper weight (really more density I suppose). Normal copier paper is 80 gsm. For printing artwork on tracing paper, a heavier paper is better if you can get it, I’m using 120 gsm (or maybe it’s 110, something around there, I haven’t got it handy at the moment)

    • elli says:

      In USA and Australia it is quite common to use the abbreviation “gsm” instead of “g/m²”, and there are probably some more countries which do so as well…

  5. Ross Potts says:

    Huh. I haven’t done much with paper. I’m used to GSM with regard to phones.

    Thanks!

  6. W says:

    I hope you’ve got some good UV goggles that you trust and/or have tested; 60W is enough to give you keratitis/conjunctivitis in very short order! I have a 25W 365nm LED module (used for fluorescence photography) that is powerful enough to make my eyeballs fluoresce and will cause pain lasting days after a couple of minutes of exposure without eye protection.

    I’m also puzzled that you’re using plexiglass (acrylic) for the windows. It is UV-absorbent (unless you buy a special UV-transmitting version) and is likely reducing the effectiveness of your box significantly You’d be better off with glass.

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