Introduction: How to Easily Solder Wires to SMT LEDs
There are a lot of cool applications where you need to embed small surface mount LEDs into things like clothing, jewelry, etc. In order to do so, you need an easy way to solder small magnet wire to the tiny LEDs. There have been other attempts at making this an easy process, but I have found nothing as simple, quick and easy as this new method.
The Solution - Duct Tape
The process is basically simple. We need to hold an SMT LED upside down so we can hand solder wires to it. The best way to hold the LED is to attach it to a piece of duct tape. Magnet wire (30 guage) is probably the best size for most applications. If you use two colors - one red, the other green, you can show the polarity of the LED during final assembly. If you don't use two colors, you will need some other way to mark the polarity.
Here are the steps:
Use masking tape to mount a square of duct tape upside-down (sticky side up) to a flat surface.
Set your LED upside-down on the duct tape and press to make sure it is firmly attached. To save time, you can mount several LEDs in one big column. Make sure each LED is facing the right way polarity-wise. The polarity is shown in the photo above.
Pre-tin your magnet wire ends. This is the most time consuming step. A solder pot would make it go much faster.
Add a small solder bead to each pad of the LEDs. Just a small dab is all that is needed.
Hold the magnet wire on the LED pad and heat with soldering iron. When the solder melts, remove the iron. Hold the wire steady until the solder solidifies. If you use a lighted magnifier to see better, this step is amazingly fast and easy, provided you have a steady hand.
When done soldering, the LED lifts easily from the tape and is ready to embed in your project. Don't forget to use current limiting resistor on your PCB or elsewhere for attaching the LEDs to.