How to insulate a circuit board?

Discussion in 'The Projects Forum' started by Kefka666, May 5, 2008.

  1. Kefka666

    Thread Starter Active Member

    Mar 4, 2008
    38
    1
    I soldered a lot of LEDs onto a circuit board, so the back of it has a lot of current-carrying wire and solder points that I need to insulate. What's the best way to insulate a circuit board?
     
  2. mik3

    Senior Member

    Feb 4, 2008
    4,846
    67
    Screw the board on a plastic surface and bend the plastic's surface edges upwards to cover the sides of the board.
     
  3. beenthere

    Retired Moderator

    Apr 20, 2004
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    289
    It is convention to mount PCB's with devices called stand-offs. They may be plastic or metallic, but hold the PCB at a distance from, say, a metallic surface.
     
  4. Kefka666

    Thread Starter Active Member

    Mar 4, 2008
    38
    1
    Here's an update. This is approximately what the uninsulated circuit looks like, taken from a similar picture found on the web (this isn't my circuit):

    [​IMG]

    What's the best way to insulate that kind of circuit?
     
  5. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
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    One could always slather on some epoxy and call it a potted circuit.
     
  6. n9352527

    AAC Fanatic!

    Oct 14, 2005
    1,198
    5
    A piece of insulating material (like a thick piece of antistatic plastic sheet) and double side tapes.
     
  7. techroomt

    Senior Member

    May 19, 2004
    198
    1
    the plastic stand-offs and screws are a good way. however check to make sure a (chassis) ground connection was not being made from the original mounting hardware. if so, you will have to re-establish that when mounting.
     
  8. Kefka666

    Thread Starter Active Member

    Mar 4, 2008
    38
    1
    Would just plain electrical tape be a good idea?
     
  9. techroomt

    Senior Member

    May 19, 2004
    198
    1
    the actual physical layout will determine that. however, if there is going to be actual contact of components/connections, then no. with heat and any vibration, the tape layer could wear through in time. multiple layers??
     
  10. thingmaker3

    Retired Moderator

    May 16, 2005
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    My experience with electrical tape is that many brands will come loose after time. I've found this to be especially true when trying to adhere the tape to flat surfaces.
     
  11. beenthere

    Retired Moderator

    Apr 20, 2004
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    Perhaps we might ask: Insulate against what? If the PCB is not in contact with a conductor, then there is no need for insulation.
     
  12. Caveman

    Senior Member

    Apr 15, 2008
    471
    1
    Exactly! If it's in a plastic box, you're done. If it's in a metal box, you use standoffs. If it's in the open air and not getting warm, hot glue or epoxy over it. If it gets too warm for that (ie. melts the glue), use standoffs and put it in a box with holes and perhaps a fan.
     
  13. Wendy

    Moderator

    Mar 24, 2008
    20,993
    2,731
    Now there's a thought I've never used, electrical tape on the case and a hot glue gun. Here I though screws were necessary.

    Seriously, in building combat robotics, where metal might be flying all over the place in high current circuits, there is a black insulative paint that is used on terminal strips. It comes off easily when dry, and does the job pretty well. Availabe at most hardware stores.
     
  14. Kefka666

    Thread Starter Active Member

    Mar 4, 2008
    38
    1
    The PCB is going to be used in the open air to light a small space, so there is a chance that someone might come in contact with the circuit if they wanted to move it and were not paying attention. Hot glue from a glue gun sounds like an interesting idea!
     
  15. SgtWookie

    Expert

    Jul 17, 2007
    22,194
    1,761
    There's a spray-on coating used on avionics boards called "conformal coat". You can get it in a spray can. It's primary purpose is to prevent corrosion and to hold things in place, but it also has insulating qualities. It's some kind of a spray acrylic laquer/polymer mix.

    I really hate electrical tape. If it's used in a warm environment, the glue gets gummy and it unravels, leaving the connections exposed. I don't use it on anything that I'm going to keep for longer than a few months.

    If the board itself will be left exposed, then you might fasten it to another piece of fiberglass or plastic, and use some kind of sealer like hot glue around the edges to keep foreign objects out.
     
  16. techroomt

    Senior Member

    May 19, 2004
    198
    1
    i really hate to see exposed circuit boards for several reasons. i would place it in a project box/case. if it's the "look" you're after, you can build a case out of plexiglass, they look nice.
     
  17. KrisB

    New Member

    Aug 10, 2017
    1
    0
    I realise this reply is about a decade too late to help the O.P,
    but I'm replying for future reference to those who might need it...

    Firstly, Never use doublesided tape or any tape other than electrical insulation tape or self-amalgamating insulation tape to try insulating electrical circuits, the adhesive on some tapes may be conductive - which means that your project may go up in a Puff of smoke (& probably a bright flash & a loud bang too)

    i've been insulating my project boards (& exposed contact spots) with a readily available & reasonably cheap product which is resistant to extreme temperatures & most oils & some solvents too - it's a silicon-based automotive sealant which is commonly known as "GASKET MAKER" or "High Temperature RTV Silicone".
    No need to waste money on the high-end ranges, you can probably get a 3oz. (85g) tube of the cheaper brands for as low as $1 - $2 (US$).
    Added bonus is that it comes in a variety of colours, so you may want to seal positive terminals with RED & Negative terminals with Black... (other colours incl. Blue, Green, Grey etc.)
    Personally I stick to the Black version for insulation of things that may need to withstand excessive wear&tear - for some reason with all the brands i've tried, their Black ones have always proven to be a tougher product with superior adhesion (compared to other colours in the same product range)

    Remember that if you're using a wet rag to smooth the silicone (before it forms a "skin"), allow the moisture to completely evaporate before applying power to the circuit!!!
     
    Last edited: Aug 10, 2017
  18. #12

    Expert

    Nov 30, 2010
    17,815
    9,127
    Use mineral spirits to smooth silicone. It doesn't react with the silicone and evaporates, but not quickly. Similar to water, do not apply power to a flammable liquid.;)
     
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