SparkFun’s 2014 factory tour of Shenzhen supplier YunSun reveals the full PTH LED production process from raw dies to finished product.
Key Takeaways
LED dies (4,000 per sheet, ~$12.50) are sourced from Taiwanese suppliers; YunSun manually places them using tweezers under a microscope at 80/min.
Wire bonding attaches a gold wire from die to anode lead; the cathode adhesive is conductive, no clean room required.
Epoxy resin molds define LED shape; mold geometry limits custom shapes since undercuts prevent release from single-part molds.
Custom LED shapes require coordinating 5+ separate cottage suppliers (die, lead frame, mold, test jig) making one-off designs far harder than expected.
7-segment displays use bare dies bonded directly to PCBs, not discrete 3mm LEDs behind diffusers.
