Micro_wiring

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Just like our 2x3 LEDs

only smaller

If you've wired up some of our 2x3 LEDs, you've gained the general techniques required to wire up the Micro LEDs. The solder pads are much smaller (as are the LEDs), but with good magnification (here I go again...), all of the same steps apply. If you need to review wiring procedures for our 2x3's, direct links are here and here.

CAUTION!

Our RED Micro LEDs are wired differently than all of our other LEDs. The mark on the LED is for the ANODE (+) connection, not the CATHODE (-) connection. For details, the data sheet is here

Let's wire up a Micro LED

Following is a graphic step-by-step wiring of a Micro LED. The wire routing method shown, we refer to as "back wiring" (for lack of a better term). The wires are routed directly away from the back of the LED. This is a useful wiring method, for example, if we were going to build a streetlight or building light and want the LED facing down from the inside of a lampshade, or to face down from the ceiling of a building interior.

Our LEDs are packaged in a black conductive plastic carrier strip. This strip contains pockets, or cavities that contain the individual LEDs and are held in place by a clear plastic cover-strip that can be pealed back to remove the LEDs. The reason that the carrier strip is conductive is that the LEDs are STATIC ELECTRICALLY SENSITIVE DEVICES. Therefore, before removal or handling of the LEDs, precautions to prevent static discharge should be taken (good grounding, anti-static mat or wrist strap, etc).
Since the LEDs are polarity sensitive devices, we use color-coded wiring to differentiate between the positive (+), and negative (-) electrical connections. In keeping with standard electrical conventions, we will connect the RED wire to the positive (+), or Anode solder pad of the LED (the electrically “hot” connection), and the GREEN wire to the negative (-), or Cathode solder pad (electrical “ground” connection). Remember that in the case of Red LEDs, the polarity marking points to the Anode (+) connection. For all other LEDs, the polarity mark points to the Cathode (-) connection. For all LEDs, the RED wire should be connected to the Anode solder pad.
Figure 1, below shows a back view of a typical Micro LED. Note the fat “T” shaped opening between the solder pads on each end of the LED. The base of the “T” points at the polarity mark. In this example, it points to the solder pad that is the Cathode, or negative (-) electrical connection. Another reminder is that (except for Red LEDs) the Cathode solder pad is shaped like a "C" (for cathode).

Figure 1

Figure 2, shows a tinned segment of red #38 magnet wire positioned over the Anode (+) solder pad of the LED. Center the wire over the pad and align the wire so that the insulated portion begins at the inside edge of the solder pad, as shown.

Figure 2

In the next step, the wire will be soldered to the solder pad of the LED. Remember, these LEDs are very sensitive to thermal shock and excessive heat. Manufacture’s recommendations for soldering of these devices limits solder temperature to a maximum of 260ºC (500ºF), and a maximum contact time (soldering iron contact) of 2 seconds. In reality, since the wire has been pre-tinned and the solder pad is gold plated, actual contact time for acceptable solder flow should be much less that ½ second. A quick “touch” with a properly tinned iron having a tiny amount of low-temperature solder is all that will be required to complete the solder joint. As mentioned in the 2x3 LED wiring procedure, as an aid to the quick and even flow of the solder joint, we recommend placing a tiny (very tiny) amount of liquid flux at the point where the tinned wire and solder pad touch each other. Too much liquid flux will require cleanup.
Figure 3 below is a cross-sectional end view of two LEDs. The left view shows a good solder joint which has a low, smooth profile. The LED on the right has a solder joint with too much solder, which also contains peaks and a general irregular surface. Again a tiny bit of liquid flux will assist the quick and even flow of solder.

Figure 3

Figure 4, below shows the red wire soldered to the Anode (+) solder pad of the LED.

Figure 4

The next step is to trim off the excess tinned wire that hangs off the edge of the LED. Using micro scissors or a sharp scalpel, carefully trim off the excess wire even with the edge of the LED circuit board as shown in figure 5, below.

Figure 5

Carefully route the red wire up, away from the Cathode solder pad as shown in figure 6, below.

Figure 6

Now, perform the same procedure (steps 4 through 9, above) for the Cathode solder pad using a tinned segment of green #38 magnet wire. See figures 7 through 10, below.

Finally, using a sharpened toothpick or similar tool, route the green and red wires up away from the back of the LED as shown in figures 2.10 and 2.11 below. The wires should exit the back of the LED parallel to each other with a close 90º bend in each wire so they lay flat on the LED back and then exit up and away as shown in Figures 11 and 12, below.

Should there be any residual liquid flux from soldering in the area between the solder pads, an easy way to soak up and remove the flux is by gently sliding a small cut piece of paper edgewise between the 2 wires so that it slides along the back of the LED. The paper is quite absorbent and very slightly abrasive, so it cleans that portion of the rear of the LED very nicely. See Figure 13, below.

This completes the wiring process for Micro LEDs. In addition to "back wiring" as we've shown here, there are other wiring schemes that can be useful for various applications. They are covered in detail in our Advanced Lighting section for our Nano LEDs. A link to that topic is here.

Remember to thoroughly re-inspect the solder joints and be sure to test the wired LED prior to installation.

Last modified: May 31, 2007