PAGE 028 OF 150 · COLOURS, SIZES & TYPES
Surface-Mount LEDs
SMD LEDs are soldered flat onto the board surface.
LED SYMBOLTriangle points from anode to cathode; the arrows show light leaving the part.
Surface-mount LEDs
SMD LEDs are soldered flat to the surface of a circuit board with no leads through holes. They are small, cheap to assemble by machine and widely used in strips and lamps.
Common package names
- 0603 and 0805: tiny indicators, 1.6 mm and 2 mm long
- 3528 and 2835: strip and lamp LEDs
- 5050: larger, often three chips in one for RGB strip
Working with them
Check the cathode marking, use a fine soldering tip, and heat the pads briefly. Many SMD LEDs have no leads to bend, so mistakes are harder to fix. Reflow or hot-air soldering suits fine-pitch work.
REMEMBER
Colour is set by the semiconductor material, not by the plastic lens.Try it yourself
Sketch the circuit on paper first, calculate the values, then build it on a solderless breadboard using a low-voltage supply. Measure with a multimeter before you make anything permanent.
Explore LED clocks, stopwatches and electronics at cosycom.com.