I wanted to make LED cards with my kids, but didn't want to purchase the LED stickers. This project provides a way to mount an SMD LED to a piece of card stock.
SMD LEDs are easy to find online for pretty cheap. They have a very low profile (good to fold into cards) and come in a variety of colors, but obviously they're tiny - too small for most people, let alone children to manipulate.
Most LED cards utilize copper tape as a trace. With a good bit of imprecision, you can place these LED tabs on the copper traces to light up. You can use tape or glue to hold the LED tabs down.
Building these LEDs requires working with very small objects. I probably could have made a template device to fabricate a lot of them, but this is more of the prototyping phase. It takes about 10-15 minutes to make each tab, YMMV.
Here's what you will need:
- Copper Tape, 1.8"
- SMD LEDs (I used 3.2 x 1.6 mm)
- Scissors to cut card stock (x-acto knife might be preferable)
- Soldering Iron
- mini cutting pliers
- tweezers and pencil to hold and move LEDs
You will still need to use appropriate resistors in your project to limit the current into these LEDs, but
Step 1: Cut Card Stock
Cut a piece of card stock about 1/2" x 1/4".
It's probably a good idea to cut a lot of these pieces at once.
Step 2: Mark Tabs
The LED is mounted to one side of the tab. The two ends of the copper must be close enough for the SMD LED to set in-between for soldering. A little overlap between the LED and the copper is preferable to filling in the bridge of LED <-> copper trace with solder (the hot solder will scorch the paper).
Make two pencil marks at about 1/8" apart. On one side of the paper, the marks are just inside the 1/8" spacing ticks, and on the other side of the tab, the marks should be just outside the 1/8" spacing ticks. You will definitely get a feel for the measurements here after a few tries. Ultimately the closer-together marks will be the LED side, and the farther-apart LED marks will be the trace side.
Step 3: Lay Tape and Cut Tape
Stick copper tape on one side, and wrap around to the other side.
Make sure the tape is just over the second line, then clip with the snips.
Repeat this step on the other side of the paper tab.
The tape job probably won't be perfect, but that's OK.
Step 4: Position LED
Either both sides of the paper tab will have exact spacing between the copper tape - or they won't.
I prefer the closer gap be used as the LED side. The further copper gap should be the trace side.
Choose wisely, or make a new paper tab.
Position the LED for the next step, which is soldering.
Step 5: Solder!
You will need to have three implements on hand
- soldering iron
- a positioning tool - I used a pencil
- Put a little solder on the tip of the iron
- Place the pencil on the LED to hold it in place
- Touch the tinned soldering iron to one side where the LED touches the copper tape.You may quickly drop the pencil and feed some more solder onto the connection.
- Once a little bit of solder flows to connect the tape with the LED, remove the soldering iron.
Do not hold the soldering iron on the paper tab for too long, or the tab will scorch
- Solder the other side of the LED without using the pencil - the LED is held in place by the first soldering connection.
You should be done.