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Posts posted by mik3ca

  1. have you tried press n peel blue? i'd give it a go except i don't like to drill holes.

    no, but according to a few articles that I read about it, it requires more effort than using the transparency method mentioned here.

    Also, Press-n-peel is not available in any local electronic store.

    and for best printing results I use the solder and the component side (solder side is blue and component side is red). On the screen they look violet but on the paper they are just black.

    If I understand you correctly, then this method is ridiculous. If the solder side is NOT supposed to touch the component side on the circuit board, then why would I print the solder and the component side at the same time on the same side of the sheet?

    That means to make an extra copy of Your layout just for printing purposes.


    Copy all traces onto the component side and the print will be deep black (as black as a road tunnel at night) printing both layers at one time. There will be no loss of the sharpness conerning traces, pads and vias. There is a good chance to fill unwanted holes on the solder side with colour on the component side.

    I tried this also on a colour laser and very much to my surprise there was no significant difference.

    I'm lost.

    For the developer I use "Aetznatron". Sorry I don't know the english word for that but the development is finished within 30 seconds. Any longer development will also erase the photoresist not exposed to light and You'll have a clean copper surface. The solution is 10grams per one liter of lukewarm water. 30 degrees will just be fine. Don't use higher temperatures. The result is unpredictable.

    The ONLY problem I have is that I'm not able to transfer the image from the computer to the circuit board successfully.
    Once I get a super-sharp image on the best paper, everything else is then OK.

    I use 3M transparencies. Hope you get it sorted out. I usually have no problems with traces down to 7 mil.

    The smallest spacing between any of my two tracks is 100um. Is that less than 7mil?
    The smallest track width of any of my tracks is 300um.

  2. I have made thousands of boards using transparencies from an inkjet printer.

    I need to learn from you.

    How old is the printer?

    about 5 years.
    My printer uses a parallel port. It doesn't support USB.

    The old inkjets did not have very good resolution.

    I don't think my printer qualifies as an "old inkjet" if sometimes the transparency works. The major problem I have with using a transparency is that the second copy of the same image does not align properly with the first copy, and the result is a shifted image, making the design useless. I have to pass the transparency through twice in order to even attempt a sharp image.

    You can get a new high resolution inkjet for US$50 if you shop around.

    I prefer to spend less than $50. I am looking for better media.

    I use darkest color and highest resolution.

    maybe I need to use the darkest colour.

    I also select transparency from the menu. I have never had to print twice.

    In that case, my transparencies are junk. What brand are your transparencies?
    I used Grand and Toy ones.

    One thing you might try is to go to the adjustment screen for your printer and fool it into thinking you are not seeing the test spots dark enough. This will cause the printer to go darker.

    I tried a super-dark setting on tracing paper, and the ink almost made the tracing paper wet. LOL

    So now I know that my transparencies are garbage.
  3. Until now, I was using transparencies as the media to put my PCB artwork on in order to complete the photofabrication process.

    The PCB works excellent with a transparency, BUT, in order for this to happen, the artwork must be excellent. In most cases, it is not. When I pass the transparency (designed for  inkjet printers) into an inkjet printer, it prints fine, but under bright light, I see random holes in my design (non-printable spots). For this reason, I need to pass the same transparency through the printer twice.

    The main problem I have with the second pass is that the two copies of the same design do not print one of top of the other. When this is successful (rarely), the image is darkened and no light can pass through it at all.

    My printer settings won't help because I already set it to the darkest setting.

    Now I am trying tracing paper. The price is excellent for each sheet, but the only problem I have with it is that it takes alot longer to remove the unwanted photoresist, and alot longer to expose the design and the board to light.

    With a transparency, I can expose a board and remove unwanted photoresist in an hour.

    I haven't changed the ratio of developer to water during both cases.

    I am wondering if there is better media to use to print the design on. I don't want to spend alot of money on it, and I want the media to work with an inkjet printer as well.

    any suggestions?

  4. ...the 2N2219 will smoke, but that will ONLY happen when the pass transistors Hfe is at it's minimum.

    You know, transistors can smoke alot easier than that. :o  Just be an idiot when connecting them.

    In fact, if you connect the base of the 2N3904 to the positive of a high DC voltage source and the emitter to the negative of the same source, I can guarantee that it will malfunction. In fact, I can guarantee that some smoke will appear.

    and why will they malfunction? because if we ignored the internal battery resistance, the current being supplied to the transistor will be infinity, and I cannot see any transistor that can handle infinite current like that.
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