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I need to widen a hole on a PCB? What's the correct way to do it?

Discussion in 'PCB Layout, Design and Manufacture' started by TheLaw, Feb 10, 2011.

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  1. TheLaw

    TheLaw

    119
    0
    Sep 27, 2010
    Hi,

    I have an amplifier board that I am essentially restoring. The original speaker wires were a measly 22AWG because the speakers were connected about 1 foot away. However, my speakers will be a few feet away and thus I will need to use a thicker gauge wire. I would like to use 14AWG but the through holes on the board can only accommodate 18-20AWG maximum.

    I have a drill press and some small bits...Can I just use them? Or is there a special way?

    Thanks.
     
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,374
    2,769
    Jan 21, 2010
    1 foot, a few feet. Unless you have illusions of having golden ears, you wouldn't notice the difference.

    40 feet, 100 feet -- OK.

    If it will accommodate 18AWG then use that.

    There are many ways to accommodate larger wire sizes.

    1) use the largest wire that will fit and connect the thicker wire to that.

    2) Use a special device for making holes to increase the size of the existing hole. In my country we call them drill bits. ;) be careful not to damage the PCB pattern.

    Note that if your PCB is double sided then you will possibly break the connection of a plated through hole and you should solder the wire to both sides of the board if there is a pad on the top side. If the board is multi-layer you will likely destroy any connection to internal layers in a way that can't be repaired.

    It is unlikely that your amplifier will be on a multi-layer board. It may even be a simple single-sided board.

    3) use a PCB pin and connect the wire to that. This is essentially a fancy version of (1) above.

    4) Connect the wire direct to the underside of the board. This is a little risky as mechanical stresses may pull the track from the board, but that is less of an issue for thin, flexible wire.

    5) Find some terminal blocks that fit your PCB.

    Pick your poison!
     
  3. TheLaw

    TheLaw

    119
    0
    Sep 27, 2010
    Actually never thought of the idea of using terminal blocks...That sounds like a good idea. Do you really think it won't be noticeable? I'm running two subs off this. I'm afraid that the wires won't be able to handle it...

    The amp board is single layer by the way.
     
    Last edited: Feb 11, 2011
  4. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

    25,374
    2,769
    Jan 21, 2010
    If the resistance of the wires exceeds (say) 0.1 ohms, then worry.

    If 1 foot of wire can "handle it" then longer wires will have no problems (unless you tightly coil them up, or do something silly like that). The resistance of the wires will affect the "damping factor" and that is the reason you want larger wires. As I said though, going from a foot to a couple of feet is hardly going to make a huge difference.
     
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