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Thread: Can I use a hot glue gun, thermoplastic, or suguru to protect contacts?

  1. #1
    Senior Member MichaelMeissner's Avatar
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    Question Can I use a hot glue gun, thermoplastic, or suguru to protect contacts?

    I was wondering if I could use a craft hot glue gun, thermoplastic (plastic that melts and can be reshaped) or suguru to go over wires soldered into prototype boards to prevent wires from touching. Ideally, one or all of these substances act as an insulator so I can protect some circuits.

    I have several steampunk props in mind. Things can move around a bit, and I thought I would add a layer of hot glue (from a craft hot glue gun) on top of the soldering to protect the wire and prevent accidental shorts. I have hot glue, and thermoplastic available on hand, and these are nice in that I can use a heat gun to melt them in case I need to make changes. I also have some suguru, and while it doesn't melt per se, it can be scraped off.

  2. #2
    I've used craft-type hot glue on boards before for similar purposes with no ill effects on the circuit. The type I used stuck, but was able to be peeled off later (actually worked in my favor, may not be desirable for you).

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    Senior Member MichaelMeissner's Avatar
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    Quote Originally Posted by madmattd View Post
    I've used craft-type hot glue on boards before for similar purposes with no ill effects on the circuit. The type I used stuck, but was able to be peeled off later (actually worked in my favor, may not be desirable for you).
    Thanks.

    On the other hand, I know not to depend on hot glue to hold anything together (i.e. act as glue), it will fail, usually in the middle of the day. But I figured, hey, I already have it.

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    Senior Member Constantin's Avatar
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    I'd try to use a glue meant for plastics. Anything designed for holding PVC to something else. The hot glue can be useful as a temporary scaffolding.

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    I'm no expert, but I coat with urethane, maybe even 2 coats. Then you could probably use most other stuff that doesn't eat away too much of it.

    Maybe liquid electrical tape over the urethane.
    I've used something like this before: https://www.amazon.com/Chemicals-Ure.../dp/B00TW2CZZA

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    Senior Member MichaelMeissner's Avatar
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    At this stage, I was thinking of temporary scaffolding while I was building it.

    Assuming I finish it,, I will probably want to go with conformal coating. Thanks for reminding me about it. Note, the one you listed is not available from amazon.com any more, but this one is:

  7. #7
    Senior Member PaulStoffregen's Avatar
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    If using glues that dry to a hard solid, be careful about whether they come into contact with surface mount parts.

    Some work fine. But others shrink as they dry. Some can dry first on the SMT parts and end up applying lateral force if the rest doesn't dry uniformly, possibly breaking the parts off the PCB.

  8. #8
    Senior Member MichaelMeissner's Avatar
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    Thanks everybody. Initially, I'm just wanting to protect the underside of protoboards where I have soldered connections too so I don't have to worry about accidental short circuits as the piece flops around. Paul good point about SMT parts (and solder pads underneath the Teensy).

  9. #9
    Hot glue is great for prototyping but obviously is not appropriate for production.

    Paul's points are spot on. Don't glue on SMT components, if you ever remove the glue you will rip the component off with the pad. THen you're hooped.

    Instead solder the wire, then tack the wire down with glue at a poitn on the PCB where no componets are, or to a mechanical component like a jack or something. This provides some strain relief and keeps it from flopping about. Also, when you remove the glue there is no risk of damage.

    Since standoffs seem to always be stupidly overpriced, and sometimes I don't have mech holes for standoffs, I've also made my own "feet" with well controlled blobs of hot glue. This acts like standoffs to get the circuit contacts away from a surface I won't want them touching (like non-static safe tables).

    If it's important the board is level, I put the glue on the board, flip it over onto parchment paper, adjust until level, let the glue harden then remove the parchment paper. Now all the glue "feet" are the same height.
    Last edited by Blackaddr; 03-21-2017 at 07:09 PM.

  10. #10
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    I've used coil dope for insulating connections. My current bottle is labeled "Super corona dope". It is sort of like fingernail polish.

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