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Board etching

Discussion in 'General Electronics Discussion' started by Allycat, Feb 16, 2014.

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  1. Allycat

    Allycat

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    Jan 17, 2014
    How many different ways are there to etch circuit board? Do they all need a laser printer?
     
  2. BobK

    BobK

    7,682
    1,686
    Jan 5, 2010
    Etching is done with chemicals, not a laser printer.

    A laser printer can be used to transfer a toner pattern to the PCB before it is etched. Other methods of putting the pattern on the board are drawing it with a resist ink pen, using photo-sensitive boards and exposing them through a film with the pattern under UV light, and printing the pattern directly onto the board with an inkjet type printer.

    A way of etching the board without using chemicals or transferring a pattern is to use a CNC machine to cut the copper away.

    Bob
     
  3. jpanhalt

    jpanhalt

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    4
    Nov 12, 2013
    Well, since a board has 2 faces and 4 edges, there are six ways it can be put in the etching tank.

    I suspect you are more interested in the chemicals in the tank. There are many ways; all depend on oxidation of the copper. It is not"dissolved," as some may think.

    Off the top of my head, common chemical methods are:
    1) Ferric chloride
    2) Cupric (II) chloride
    3) Ammonium persulfate
    4) Sodium persulfate
    5) HCl + hydrogen peroxide
    6) Electrochemical + chemical
    7) Alkaline (mostly commercial), see: http://www.chemcut.net/downloads/alkaline-etch-process.pdf

    Ferric chloride is still the most common method. It is noted for having the least undercutting of the etched tracks. Notice, if you start with ferric chloride and replenish by re-oxidizing the bath and adding additional acid, you end up with a cupric chloride bath. The electrochemical method is interesting in that the copper is plated off the board until individual traces are separated. Then. the final removal is with conventional chemicals.

    Chemcut is a good source for information on etching PCB's.

    John
     
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