Recently we made a long video with us testing out our Maker Tape and Copper Foil Tape to see how much power they could handle. We had a request for a more detailed write up and we decided to go full 'Middle School Science Teacher Lab Write Up' on it. While we didn't make up any fun graphs we do go into some heavy detail about it.
We use conductive tape for all kinds of projects; from simple paper crafts to complicated Arduino projects. We've often been asked the question "how much power can conductive tape handle?". While we've never run into any issues over the past six years we decided that it was high time we ran some tests to find out just how much stress conductive tape can handle.
Note 1: Don't try this at home without adequate protection. Even though the dangers of this experiment are very minor, no one wants to get burned or shocked.
Note 2: We're throwing way more amperage at conductive tape than anyone would ever reasonably do for conductive tape activities. A CR2032 battery, which is the most common power source used on conductive tape, is only able to output around 50-100mA. A typical USB wall charger is between 1 - 1.5A of output.
The Equipment and Procedure:
For our test we used both standard copper foil tape as well as our own Maker Tape, which is a steel nylon tape that we enjoy using due to its increased physical strength and durability. For equipment we used a 30V 5A benchtop power supply and an inexpensive constant current tester we bought off Amazon. We used some wingnuts and long machine screws to suspend the tape samples off the table. For testing we used a thermal camera and a meat thermometer. Our plan was to use approximately 1 foot strips of tape and see how much amperage it could handle.
Before we started we tested out several lengths of tape with a multimeter to test resistance. The copper foil tape was between 1-3 ohms per foot. This was expected as it is just pure copper and is pretty much just a flat copper wire. The Maker Tape ranged anywhere from 5 to 15 ohms per foot. This variation is most likely due to the fact that the tape is a nylon steel weave, and is more similar to conductive fabric than to a copper wire. Both types of tape also featured conductive adhesive on the backside and had a wax paper backing when coming off the roll.
First we tested the 1/4th inch wide copper foil tape. To no ones surprise it handled 30V at 5A (150 Watts) without a problem. After five minutes the copper foil wasn't even warm to the touch. Again, copper foil is pretty much just a flat copper wire and easily transfers both heat and electronics very well.
Second we tested out 1/4th inch wide nylon Maker Tape. We started at 1A and left it there for awhile. At that amperage the tape didn't appear to increase in temperature, at least not that we could tell. For reference 1A of current would be about equal to powering 100 5mm LEDs in parallel or around 30 NeoPixels turned to white on max brightness. (NeoPixels have three internal LEDs which would each draw about 10mA each when bumped up to full brightness. We also assumed that a standard LED with a current limiting resistor would draw about 10mA, one without a resistor could be up to 25mA)
We then bumped it up to 2A of current and the fun started. At 2 amps the tape instantly heated up to about 105F. We left the tape at this amperage for around five minutes without it increasing in temperature. For reference this would be the same as powering 200 5mm LEDs in parallel, or around 66 NeoPixels at max brightness set to white.
Moving up to 3A of current caused a slight burning smell to emanate from the tape. We suspect it was the adhesive burning as the nylon warmed up. In case you're wondering, nylon starts to melt around 370F. Our handy meat thermometer gave us a reading of around 165F on the conductive tape, and thats where it stayed. For reference this would be 300 5mm LEDs hooked up in parallel, or around 100 NeoPixels turned to white on max brightness.
Moving beyond 3A is where we started to find the limits of the tape. Through quite a few tests we found that around 3.5A the Maker Tape burned itself out, acting like a fuse. We would hear a small pop and see a small spark, and then the connection was broken. In fact there was a very clear and straight 1/4th inch break down the tape, typically in an almost perfect straight line. We suspect small imperfections in the steel/ nylon mesh were causing hot spot flair ups or small 'shorts' to happen. We repeated the experiment dozens of times and at a length of 12 inches the tape generally failed at around 3.5A of current.
We repeated the experiment with 1/8th inch Maker Tape. At 1A the 1/8th inch tape performed quite well, and started to heavily heat up when moving to 2A. Not surprisingly the tape tended to 'break' at around 2.25A of current. Like the 1/4th inch tape this tended to be a straight line break that happened with a small spark and a 'pop' sound.
Now for the fun. We started testing smaller and smaller strips of 1/4th inch tape to see if we couldn't get a higher amperage through it. We kept finding this difficult as at 8, 6, and even four inches we would get a 'break' in the tape at around 3.5A. Eventually we managed to throw around 5A of current through a 1 inch strip of tape for a minute. The tape smoked, charred, and then briefly started on fire. This was very difficult to replicate and it took over 40 different attempts to get even the minor flame that we needed for our video.
As we suspected the copper foil didn't have any issues up to 5A of current.
Our 1/4th inch nylon based Maker Tape was perfectly safe to use up to 1.5A of current, staying at or slightly above room temperature. After that the tape would increase in temperature to around 105F at 2A and could cause issues. It was most certainly dangerous to try going above that as 3A would result in temperatures of up to 165F.
The 1/8th inch tape was perfectly safe at 1A with uncomfortable heat starting at 1.5A.
The one very interesting aspect of the Maker Tape was that it acted like a Fuse at higher amperages, causing a clean break whenever the tape went above 3.5A of current. In fact it was quite difficult to cause a small flame to happen even when using very short strips of tape.
Most of the projects we make with our Maker Tape are using CR2032 Batteries or the occasional AAA battery pack. We recently built a 6x6 NeoPixel Matrix using 1/8th inch tape for a teaching conference. It ran for over 8 hours on day and the tape wasn't even slightly warm to the touch.
The benefit of copper foil really fall down to the ability to solder onto it and the low price, however it is extremely fragile and prone to breaking. Plus the very cheap copper foil typically doesn't have conductive adhesive. While our nylon based Maker Tape doesn't have the massive conducting power of copper and you can't solder to it, the indestructible nature of nylon makes it really easy to make all kinds of complicated projects without having to worry about it breaking. Plus it's easy to peel off once you're done with a project.