Hand Wiring 2mm Neopixel LED Strips

 While I have occasional tested or prototypes with 2mm using modified surface mount adapter boards, it's always been a real pain. There is a way to point to point solder together the simpler 4 pin Neopixel LEDs.

 I ran across a variation of 2020 size LED with Castelian style tabs that make point to point wiring more practical than typical surface mount components, those with miniature modeling or SMD circuit repair equipmment and experience should be able to handle it.  

Their WorldWideSemi brand numbers are WS2812C-2020 for 5ma and  WS2812B-2020 with 12ma per LED .  

 

Here's an example of the first 5 LED string I tried, the string is 1.2mm long (Using an international standard micro SD card for size reference instead of a coin)

 

Key to the process is to first layout the LEDs face down on a highly sticky material, (I used double sided heatsink tape).

 This rough diagram shows the arrangement and connections, the LEDs in the drawing are rotated 32° for best pin alignment.

I start be directly soldering the the Data out and Data in pads of adjacent chips to lock in their positions, that soldering bare wire VDD and Ground buses.  I brought out the ground lead from the opposite end of the string top reduce chip connection clutter.

These parts have cooling issues when bunched together, more so with no copper mounting pads, best to limit the brightness.

Handle carefully, if flexed like a normal LED strip, data connection pads will break off the chips. Adding some sort of rigid backing would be important for wearable applications.

  Here's a short test of metronome patterns (my cheap camera poorly represents the colors)

 

A 25 element version seemed to function properly using wire-wrap gauge wire, with no bypass capacitors on the 50 mm long string.