How you make PCB?

Discussion in 'General Electronics Chat' started by shubham161, Aug 5, 2012.

  1. shubham161

    Thread Starter Member

    Jul 22, 2012
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    look at this video on youtube

    http://youtu.be/tWnfnt2rNO0

    it seems a nice way to make PCB but i am not able to understand it. how he transferred the toner to copper clad without ironing it? he put in under light and did something? was that a light sensitive copper board? can you help me?
     
  2. nerdegutta

    Moderator

    Dec 15, 2009
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  3. MrChips

    Moderator

    Oct 2, 2009
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    If you follow the video carefully, he is using a precoated board, that is, a board that is purchased with a layer of photoresist already coated on the board.

    There are two types of resist: positive and negative. The board he is using has a positive photoresist. With a positive resist the areas exposed to light are removed by the photoresist developer.

    With a negative process, the reverse happens. The mask consists of clear images where the traces are wanted. When exposed and developed, the unexposed areas are washed away.

    There are a number of things that you can do differently.

    1) Use as much copper pour or fill as possible to reduce the amount of copper to be etched away.

    2) Instead of ferric chloride I use ammonium persulphate for etchant.

    3) Heating the etching and constant agitation make a huge difference in the time it takes to etch the board.

    4) Leave the resist on the board to prevent the bare copper board from tarnishing. The hot soldering tip will burn through the resist and make the solder joint.
     
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  4. shubham161

    Thread Starter Member

    Jul 22, 2012
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    can you give me links to some online store from where i can purchase such boards? I may not purchase from those stores because they may not ship boards to India but those links will definitely help me to get important keywords for advance search and i'll also know the approx price for such boards.

    and what about the uv light? are they expensive? do i have to make my own circuit?

     
  5. BMorse

    Senior Member

    Sep 26, 2009
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    He mentioned on the video that he only used a 13 watt CFL bulb, you may also be able to use a 100 watt incandescent bulb, you do not need a UV light....

    If you watched the video all the way to the end, they mention the part numbers and where to get the materials from (Jameco)....
     
  6. nerdegutta

    Moderator

    Dec 15, 2009
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    I get the best results with the boards from Bungard

    The UV-Led I bought on E bay was this type.

    At the end of the video, there's some part numbers to Jameco.

    Part 2113244
    Part 2113252
     
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  7. dumindu89

    Member

    Oct 28, 2010
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    Why do you recommend persulphate over ferric chloride?
     
  8. Markd77

    Senior Member

    Sep 7, 2009
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    It's clear so it's easier to see the etching, also it smells better, but both work fairly well.
     
  9. BMorse

    Senior Member

    Sep 26, 2009
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    Hate to bump this thread, but, I ended up purchasing the kit referred to in the video, (It had the photo developer, 2 presensitized boards, and the etching solution), I thought I would just try it out for kicks and see how well it works (since I do have my own CNC PCB mill, I don't have to use the etch method), it worked quite well, and fairly easy, just follow the included instructions and off you go, all I used was a 24 watt CFL bulb (Spiral kind) to expose the PCB and the etching came out very well if I should say so, but check for yourself, I made this PCB from it for my outdoor wood boiler monitor I used a 44 Pin TQFP PIC16F887, even soldered it on by hand :cool: (and double checked for solder bridges with a 60x magnifier!)

    positive etch.jpg
    New photo etch PCB.jpg
     
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