UV Led's

Discussion in 'General Electronics Chat' started by R!f@@, Oct 5, 2011.

  1. R!f@@

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    So .......I got some 5mm UV led's, like 50 of 'em.

    I checked one.
    @5V, with 220Ω, the led barely glow. :confused: I doubt it would do any good.
    So I measured current and ramped the voltage till I=40mA.
    Then it gave a low UV glow like UV lamps.

    Forward voltage was 3.6V.

    Does the brilliance decide the PCB transfer time, duration , better transfer or whatever. ?
    Somebody help me out here.
    puleeeeeeeeeeeese.!!
     
  2. bertus

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  3. R!f@@

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    I am rather concerned on the amount of glow
     
  4. nerdegutta

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    My 45 LEDs glow with a blue/violet color. To get a decent result I found that about 10 min exposure was enough.

    If I've measured and calculated correct, one LED have a Vf of 3.34v.

    [​IMG]
     
    Last edited: Oct 5, 2011
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  5. R!f@@

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    [​IMG]


    [​IMG]



    Above are the clads that I have. Would it suffice?

    Why the 2 PCB's are different?
     
  6. nerdegutta

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    My boards come with a protective plastic sheet I have to peel off right before I put them on the UV box. Did yours? If they did, and you removed the plastic cover, they might be damaged. Not useless. You can still use the toner-transfer method. Just clean off the rest of the photoresist first.

    [​IMG]

    The boards can be made of different material. Epoxy or FR4 or something. The photoresist might also differ...

    Some of my board are nearly transparent when the are done, while others are completely brown.
     
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  7. R!f@@

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    They did not have any protection what so ever.
    The boards are very strong indeed, not like the vero ones I use to make simple circuits.

    So what method goes for these boards?
     
  8. shortbus

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    If the boards don't have a UV coating they must be cleaned and a coating applied. They do make a spray, like paint, but most boards are spin coated in a machine to get the coating even. Uncoated boards don't work with UV. The boards I bought came in special black plastic envelopes that you kept them in until ready for use.
     
  9. R!f@@

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    What are my options?
     
  10. gopalyajur

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    Rifaa,

    If your boards did not have any protective cover then most probably they are not coated with any photoresist. The photo resist is pretty much sensitive to sunlight. I have seen people using sunlight to develop boards without any special setups. Anyway you should wait for comments from experts.

    Why dont you use toner transfer method? Its much easier and works pretty well. I have had very good success with toner transfer method. If you want I will try to upload some pics of PCBs I made with toner transfer method.
     
  11. nerdegutta

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  12. R!f@@

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    It's never that easy HUH!!

    I've seen bill's method...then I thought I could use UV.
    Bill is a great guy, he sent me the wax paper and I did not ask for it.

    Guess UV's out of the question..doh.

    Oh well !! Time to find a laminator.......
    this is going to be fun....
     
  13. darsie

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    Feb 19, 2010
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    UV is invisible. Many UV LEDs are at the transition between UV and VIS, so they emit both UV and VIS. If your LED is dim or stays dark entirely it may emit an unknown amount of UV. Driving it beyond specification may reduce its service life and brightness quickly after an initial increase.

    You can check the UV output by shining it at a fluorescent substance, like "neon" colors such as a highlighting marker pen, most paper, detergent for white clothes, white clothes, etc.
     
  14. jaclement

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    I have had little luck with toner transfer methods for printed circuit generation using glossy cheap paper until I tried Techniks "Press and Peel" paper which I purchased from All Electronics part # TEK-5. It is not cheap, but if you print your artwork on regular paper, and the cut a piece of Press and Peel to cover that artwork, tape in place, and reprint in the same orientation, you wont need much. You must use a laser printer for this. (the toner is the resist)
    When you have printed onto the Press and Peel, cut both out (keep together) and place on the clean dry copper. The plain paper will protect the transfer sheet from the iron.
     
  15. R!f@@

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    :confused: Ummm!! Come again.
     
  16. gopalyajur

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    Rifaa,

    Dont worry. After some trails you will be able to make good PCBs using laminator. Attached is my recent PCB used for fast Nicd/NiMH charger using eagle cadsoft. This is not the best board I have made and there are some defects in the tracks which I have tried to cover with permanent marker. But, I have made much better boards which I cannot show you now.
    I am moving to a new place and I have packed most of my things. My wife insisted I should first pack my electronics juck :(.

    This is how I make my PCBs

    1. Clean the board with acetone. Use Gloves!!!. You could also clean with normal kitchen cleaner solution with scotch brite.

    2. Print the layer on a normal A4 paper using a laser printer.

    3. On the exact printed area attach shiny magazine paper using scotch tape. I feed this sheet again in the printer and now I have the layer on the magazine sheet.

    4. Fix the magazine sheet on the copper board (using scotch tape) and feed through laminator. Repeat this step several times. Scotch tape would melt partially and stick to the board. Dont worry this can be cleaned easily by scratching.

    5. Drill holes and etch.

    Hope it helps
     
  17. R!f@@

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    You are moving ? You guys sure love to move....

    Electronics Junk ? Eh! ....Hehehe..same reply here.
     
  18. Mickster

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    Jan 10, 2010
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    @R!f@@,
    This may be a little late, but the reason you have two types of copper-clad board is because of their composition.
    The 1st pic looks to be a phenolic board and the 2nd looks to be FR4.
    Both of these bare boards are more suited to toner transfer of artwork, rather than UV exposure, due to the reasons pointed out previously....You need a uniform thickness layer of photoresist to get the best result and the likelyhood of getting that from a DIY process is pretty low.

    I know you are already proficient at soldering from your many past posts, but there are also differences between these two types of board when it comes to soldering & drilling. The phenolic boards are easier to drill, but more fragile when it comes to soldering....too much heat or lingering too long with the soldering iron can cause these boards to bubble quite quickly in my limited experience. FR4 boards are more forgiving with the soldering, but a little harder on drill bits.

    As for the toner transfer method, there are loads of suggestions on the web about which printer/paper/special film/laminator/iron to use. You may have to experiment a bit to get the best results for your particular laser printer/paper/film/laminator/iron combination.

    I have had decent results with Blue Press 'n Peel film, used both with a clothes iron, or run multiple times through a standard laminator. The laminator needs to get up to temperature, so probably let it warm up for at least 15 to 20 minutes before passing a PCB through.

    You can also use glossy magazine paper to transfer the artwork. IIRC, you should use paper with a high amount of clay since it releases easier, but the drawback of using magazine paper is that you have to let it soak and probably need to scrub lightly with a toothbrush to remove the paper pulp.

    I am using the Blue Press 'n Peel film and running it through the laminator multiple times, in different directions and also upside down. I find that when the PCB is almost too hot to hold, the artwork is pretty well transferred. Any tiny blemishes get touched up with a Sharpie marker pen.

    HTH.
     
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  19. R!f@@

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    Thanks Miky, it never is too late for an advice.

    Actually you gave the info I needed about the clads I have. I did not know about which clad gives me soldering trouble as I have seen some boards do bubble. Never realized why the heck some boards does that until now.

    Drilling is not an issue to me. I will finds ways to get around it. Only problem is the transfer.

    I plan on using the wax paper Bill sent me. Still trying to find a laminating machine to get the heaters and make a suitable one that I could use always.
     
  20. R!f@@

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    Which transfer method is best..
    UV or Thermal
     
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