Working with Surface Mount LEDs for Paper Circuits


Over the past couple of weeks in the Tinkering Studio, we have been continuing with experiments with paper circuits in our workshop space. One thing that we are thinking about is how to refine our facilitation strategies to help visitors work with the tiny surface mount LEDs.

paper circuit solder tutorial
These lights are extremely small and can be a little difficult to work with. I wanted to share a couple of tips and tricks that we have developed through our experiments on the floor.

paper circuits solder tutorial
paper circuits solder tutorial
The first thing is to figure out how to handle these little lights. While we have tweezers available, but have found that it works well to immediately put the LED on a piece of scotch tape to make it easier to handle. It's fine to just put the LED right on the design with the scotch tape. Make sure to press down hard on the edges so that the light makes a good connection.

Paper Circuits Solder Tutorial
For a more permanent connection, it's nice to solder the LEDs directly on the copper tape. This is a slightly more advanced technique and I wanted to run through the steps needed to get the LED connected.

Paper Circuits Solder Tutorial
First stick the solder on one of the pieces of tape (make sure that they are close enough together that the light can span the gap).

Paper Circuits Solder Tutorial
Then pick up one of the LEDs with the tweezers and hold it right next to the blob of solder. With your other hand, melt the solder and stick the LED into the liquid metal. Make sure to pick up the soldering iron before the tweezers. The LED should now be firmly stick in place.

Paper Circuits Solder Tutorial
Finally, now you should be able to solder the other side onto the other piece of copper tape. Make sure both the metal lead on the side of the LED and the copper tape gets hot enough for the solder to flow and connect.

Paper Circuits Solder Tutorial
Test your design and hopefully you will have a bright light shining on your paper circuit. When you add more lights make sure they are all in the same direction (you can tell from the diagram on the back or the tiny green dots that are on the front side).

Soldering a Surface Mount LED for Paper Circuits from The Tinkering Studio on Vimeo.

We also made this quick video to show all the steps needed. Working with a soldering iron takes time and practice so don't be too frustrated if you don't get it perfect on the first try. Keep at it and you'll be as good as Ryoko in no time.

HI- How do you know which is the positive and negative side to these mini leds? I was advised that there is a small triangle to indicate the '-' however. I cannot see a thing on these. I thought there was a trick ie the side with the strip holes were the positive... or something like that. Also. what do you do to cut these and how close can you cut it? Thanks for the video- it was very helpful!

If you look on the underside of the LEDs (the flat side) there is a little green dot. It is hard to see, as they are very small, but it is there. That marks the negative (–) side of the LED.

As far as I know these types of LEDs should not be cut, they come in individual little blisters.

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