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Homemade PCB

Discussion in 'General Electronics Chat' started by beakie, Jun 15, 2010.

  1. beakie

    beakie New Member

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    Hey

    I am about to etch my first PCB. I just wanted to discuss what I intend to do as there are so many different techniques online.

    ETCHING
    Photo etching. I have a 125W grow lamp (blue spectrum) for other reasons :) Will this do?

    TINNING
    Do I need to do this?
    Once I have etched my copper tracks, do I need to tin the whole board?

    FLUX
    Do I then need to flux where the components go? If so, what sort of flux should I use? I can only get flux pens from maplin. They have no clean and rosin... which will i want?


    Cheers
     
  2. 3v0

    3v0 Coop Build Coordinator Forum Supporter

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    We talk about this quite frequently.

    Tin plating is optional.

    Regarding flux. Most electronic solders have a flux core. If you do not tin plate the PCB using a flux pen will make soldering easier, esp if it oxidizes a bit. Either rosin or no clean is ok. Cleaning after soldering is not a bad idea with either. I use dish soap and a tooth brush.

    For non SMD boards I spray the freshly etched PCB with a very thin coat of clear acrylic. The heat from soldering will remove it but you may take an extra second. Some people like this method, others do not but I expect they have the acrylic too thick.
     
  3. beakie

    beakie New Member

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    What are the benefits?

    OK, thanks


    Good stuff, got me a can right here purchased from maplins only 1 hour ago :)
     
  4. dave

    Dave New Member

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  5. beakie

    beakie New Member

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    What paper is best for etching with using an inkjet?

    UK brands would be good...
     
  6. 3v0

    3v0 Coop Build Coordinator Forum Supporter

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    I do not not photo resist so I can not help you with the paper. I was thinking you needed a transparency but not sure.

    Tin plating keeps the copper from oxidizing. In theory it is supposed to make soldering easier. If you use the acrylic the copper can't oxidize. But by thin layer I mean on quick pass with the spray can.
     
  7. MRCecil

    MRCecil Member

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    It may or may not, but you will have to do some testing for results, IF the UV density is great enough in the wavelength, to which the resist will react. There are a host of other variables to consider:

    1. Exposure time vs. UV density;
    2. Focused vs. unfocused light;
    3. Distance from target;
    4. Perpendicularity of the light...reflected light can cause inconsistant exposure across board;
    5. Quality of the mask (porosity);
    6. Uniformity of resist thickness;
    These are a few general expose considerations from my own experience with this and from 11 years of lithography experience in semi fabs for Intel.
     

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