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I am planing on printing something that will make contact with PCB boards. The print will be most likely to be in PLA. I don't want to fry the PCB board so I want to know if 3D printed PLA objects are conductive.

I googled and found out about special non-conductive PLA and conductive PLA. But what about the conductivity of normal PLA?

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    $\begingroup$ If it was conductive people would already be using it for 3D printed PCBs. $\endgroup$
    – Tomáš Zato
    Feb 11, 2017 at 3:31
  • $\begingroup$ Technically everything is conductive to some degree. Unless you've got some super sensitive components in general you'll be good. PLA can be used as an insulator so long as the voltages are low enough i.e. the 3-9 volt range you're probably good to go $\endgroup$
    – Diesel
    Sep 21, 2020 at 20:44

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Normal PLA is non-conductive. You can take an $\Omega$-meter to a test part if you're really concerned somehow you have some PLA that is conductive.

There is a caveat that your color may include metal flake or graphite of some kind. Depending on the density it may be conductive. But I've tested my silver on hand and it gave me infinite resistance.

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  • $\begingroup$ Okay, good to know. Thanks! I would test it with a meter but I don't have one. $\endgroup$
    – Alic
    Feb 1, 2017 at 18:11
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    $\begingroup$ @Alic cheap meters are pretty cheap. Example, which I can't vouch for: amazon.com/Ranging-Digital-Multimeter-Voltage-Current/dp/… . If you're doing anything with circuits, you'll be much happier to have at least something like that on hand though. (Better ones are better, but more expensive) $\endgroup$
    – fectin
    Jun 17, 2017 at 1:19
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    $\begingroup$ One note, EVERYTHING is conductive to some degree. The OP should keep in mind that for their case non-conductive PLA will 'probably' be fine for their application. 3D printers are fairly low voltage in general. But, don't treat it as gospel in all cases. I.e. Don't make a high voltage shield out of PLA...or any 3d printed plastic, better yet just don't mess with high voltage period. $\endgroup$
    – Diesel
    Oct 2, 2017 at 1:25
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PLA itself falls in the category of non-conductors, with a resistivity ($\rho=R\frac A l=\frac 1 \sigma$) in the order of $10^{16}\ \Omega \text m$ (see here), similar to other plastics. Following image gives an idea of the values of resistivity for usual conductors and isolators, insulating materials have resistivity greater than $10^9\ \Omega\text m$, conductors have it smaller than $100\ \Omega \text m$ (copper is about $10^{-8} \ \Omega \text m$):

enter image description here

However, PLA can be mixed with some amounts of a conductor as graphite, making the filament a conductive material (not as good as, by example, copper). This filament can be used to create some kinds of electric circuits.

Other additions (coloring, ...) could also change slightly its properties.

Obviously, if PLA reaches glass transition temperature or melting point, holes can appear in the surface, breaking insulation.

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PLA is non-conductive at room temperature, but when you heat it up over 70 C it is no longer as great an electrical insulator as the part will begin to fail. These temperatures could occur in electrical shorting situations or even increased electrical resistance in a circuit over time. I would hesitate to use PLA in electrical scenarios with a lot of load. As the resistance drops in the PLA (The resistance is still very high) and load begins to run through the PLA you have a recipe for a fire.

http://onlinelibrary.wiley.com/doi/10.1002/eej.21272/full/

The other problem with a printed PLA part is that many times they are permeable to liquids. This means that if you say you get salt on them say from your hands and condensation say from your humid living environment... current cant pass through your plug.

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    $\begingroup$ Is this really a practical concern? The paper shows the conductivity rising from 10^-17 S/m at 25C to 10^-12 S/m at 150C. That still (even at a temperature at which the part has pretty much melted) isn't very conductive at all. $\endgroup$
    – Tom van der Zanden
    Sep 26, 2017 at 6:59
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    $\begingroup$ Is "a lot of load" at welder scale, mains scale, electronicals scale, or bioenergy scale? $\endgroup$
    – YetAnotherRandomUser
    Oct 31, 2017 at 0:32
  • $\begingroup$ Under nominal use cases you will not run into a problem, but that isn't really the concern. The concern is when things go wrong or things get wet. pevly.com/wp-content/uploads/2017/06/ABS-ANET-A3-heatbed.jpg Your heated bed for instance can have runaway resistance resulting in the plastic heating up well beyond 150C which is lower than the temperature you roast a chicken. $\endgroup$
    – Dave Pena
    Nov 1, 2017 at 1:49
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It's non-conductive, but I would check to make sure with any colored filament. Black may have iron oxide or carbon black which may give it minor conductance.

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