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Electric Conductive Adhesive

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12 commentaires

  • Boss .

    No, but I required a strong PLA 3D part and found it was a lot weaker when stressed across the printed layers, so I did a search and found others had used "super glue", so I tried one of the basic Cyanoacrylate's like this
    https://uk.rs-online.com/web/p/glues/9082802/ It was 'sucked' into the print and made it very strong, so must 'stick' well!

    That's what I would suggest trying along with one of the primers if you have problems.
    https://uk.rs-online.com/web/p/adhesive-activators-primers-debonders/0108722/
    These are often sold as a pair with the glue in DIY stores, the above one even suggests it works with PTFE.

    Whatever you try, please post your results.

    edit... just read your post again with the subject... I would do as above to robustly fix the insulated part of the wire for strain relief, then use a silver loaded epoxy to make the electrical connection.

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  • Richard Caldwell

    You are correct Boss, superglue will adhere the wires very well. On this design, I need to make a connection as shown in attached screen shot. That why I need for the coating to be electric conductive.

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  • Boss .

    Hi Richard, thanks for the image, looks good.
    Just to clarify the problem, are you trying to join the wires to a conductive pad, i.e. the blue circles?

    Or as I now suspect you want to create a conductive surface with wires connected? If this is the requirement the closest I have done is use spring contacts with wires soldered and epoxied into position, i.e. the connection is the spring contact (which was a great compact sprung loaded pin salvaged from an HP handheld computer battery).

    If it is the latter I suggest trying to find a suitable contact and connect to that. 

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  • Richard Caldwell

    Here another screenshot that shows the wand holding straps. The orange surfaces is what I want to coat with the conductive coating.

    Yes, spring contacts will also work. I guess I had a mental block because I did not think about using spring contact (blushing face). Using a spring contact will be a heck of alot better contact then just the coating. Do you have a suggest where and what type of contact I could use?

    Thanks for your great in sight and wisdom.:)))))

     

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  • Richard Caldwell

    Boss your a very wise man.

    I found this on the web and it is made by Molex. I think it fulfills my requirements and needs to a T. What do you think?

     

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  • Boss .

    Thanks! Just down to years (and years...) of making things!
    Yes they look good and the 'spring' in the pin will help maintain a connection for any movement and vibration at the mating contact.

    Hope it goes well, your 3D design looks impressive.

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  • Brad Levy

    Don't forget about addressing how to keep the contact in place. Most of those terminals are part of rectangular connector product lines. They freqently have a tab on the shose spring terminals are usually designed to go into specific connector housings. It is fine to re-purpose them the way you are doing. But don't forget about addressing how to keep them in place. There is frequently a tab on the bottom side designed to catch on a hole or depression in the housing to keep the terminal from sliding out once it has been inserted, but allowing the terminal to be removed for repair, etc. by depressing the tab through the hole in the housing while pulling on the wire. If you don't need that level of repairability, gluing in place could work. Or placing a "strap" across the set of (it looks like) four wires/terminals in you application, with hollows in the strap deep enough for the tall crimp in the photo of the contact, but short enough in length to prevent movement of the terminal in the direction of the wire. Then you just need to address how to keep the strap in place, but you have more flexibility there, since you can control the design of the strap, and the means of retaining the strap doesn't have to be as small as that for the contacts.

    There are also somewhat similar contacts designed that mount to a PCB instead of being crimped to a wire. They are frequently used for making connection to batteries in cameras, or in charging cradles for portable devices. You will sometimes find them listed under Spring Fingers.  They are available from multiple manufacturers in a range of heights and contact forces. Some are designed for making contact to EMI shielding materials, where you might want multiple low-force ones making the ground connection at locations around the perimeter of a case. Others are designed with more concentrated contact force for signals lines, where the reliability of each individual connection is more important.
    Examples (these happen to be from TE Connectivity):

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  • Richard Caldwell

    Hello Brad

     

    Yes, I looked at the PCB spring connectors but I did not see how I would connect the wires without a PCB.

    With the one I have selected I can crimp the wires on the connector. What I plan to do is to redraw the model with slots for the connector. Then when I assembly the unit I will crimp the wire. Then place a drop of super glue to hold the connector in place while I solder on the wire. The heat from the iron will soften the plastic enough to press the connector in, making a very firm seat, Once the plastic is soilife I then encase the foot of the connector in epoxy. This should hold it in very very firmly.

    Any thoughts about the way I plan to install the connector?

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  • Brad Levy

    That approach sounds workable. I just didn't know if you needed the ability to remove the wires later or whether one-time permanent assembly of wires to the 3D printed housing was okay. 

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  • Richard Caldwell

    Yes, the contacts and wiring is permanently and can not be removed. I did this to ensure contact with the wand power source.

     

     

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  • Brad Levy

    While the spring contacts are probably the better solution in this particular design instance, I just got an email about a high quality (aimed at applications including outer space) conductive adhesive from Master Bond, that may be good to remember for other applications. It is capable of filling thicker gaps, etc. It does require heat (a modest 65°C) for curing,  which might be an issue if you are using a particularly low-glass-temperature 3D printing filament.

    https://www.masterbond.com/tds/mastersil-151s 

    Master Bond MasterSil 151S is a two component, silver filled silicone with superb electrical conductivity along with good heat transfer properties. Part A has a smooth, paste consistency, Part B is a low viscosity liquid. The mix ratio is 100 to 5 by weight. Upon mixing, MasterSil 151S retains its smooth, paste consistency. The working life for a 50 gram mass is 6 to 12 hours. The best cure schedule options are 4-6 hours at 150 to 180°F and 2-3 hours at 190 to 210°F. The system has low shrinkage upon curing and reasonably good dimensional stability.

    MasterSil 151S bonds well to a wide variety of substrates including metals, ceramics, glass, composites as well as many types of rubber and plastics. The system has very good flexibility and elongation. Consequently, it can withstand aggressive thermal cycling as well as mechanical and thermal shocks. Its paste consistency allows it to be easily applied as an adhesive, sealant or coating. It can also be utilized as a form-in-place conductive gasketing material. Since it is an addition cured system it cures readily in thicknesses up to and beyond 1/4 inch thick. The color of Part A is silver and Part B is clear. The service temperature range is -80°F to +400°F. MasterSil 151S is most likely to be considered in aerospace, electronic, opto-electronic and specialty OEM applications, where excellent electrical conductivity, resounding flexibility, high temperature resistance and low outgassing, are necessary requirements.

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  • Richard Caldwell

    Thanks, Brad ( ͡° ͜ʖ ͡°)

     

    That's sound's like the perfect coating. I just know if I can form properly on the curved surface.

    Here is a rending of the unit. The copper wires is what I will be coating to ensure maxium power transfer. The other clamp is not shown so show the spring contacts and the stirp wire.

     

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