Lightbulb Teardown

Parts Overview

1. Outer Shade
   Material: Polycarbonate plastic
   Function: Acts as a diffuser for the LEDs (3.)
   Manufacturing Technique: Injection molding
2. Central Housing
   Material: Polybutylene terephthalate
   Function: Holds all internal components (3., 5., 6., 7., 8., 9.) and provides insulation and structural support between the hot electronics and the metal base (4.)
   Manufacturing Technique: Injection molding
3. Flat LED Panel
   Material:
   Substrate: Aluminum metal-core printed circuit board
   LEDs: Semiconductor chips (gallium nitride, GaN) mounted in epoxy or silicone encapsulants
   Function:
   Substrate: Spreads heat away from the LEDs to maintain efficiency and lifespan
   LEDs: Generate light
   Manufacturing Technique: Metal-core PCB fabrication, surface-mount technology (SMT), reflow soldering
4. Metal Screw Base
   Material: Aluminum
   Function: The threaded part connects mechanically to the socket’s neutral line, and the bottom tip contact connects electrically to the live line.
   Manufacturing Technique: Cold heading, thread rolling, stamping, nickel plating
5. Circuit Board (Labeled E64353)
   Material: FR-4 fiberglass PCB with copper traces
   Function: Holds all the electronic components (6., 7., 8.) in place and provides electrical pathways through the copper traces that connect components together
   Manufacturing Technique: Laminating, copper cladding, photolithography and etching, solder mask application, silkscreen printing
6. Inductor
   Material: Copper wire, ferrite core, plastic insulation
   Function: Filters electrical noise, smooths current, and improves efficiency
   Manufacturing Technique: Wire drawing, encapsulation
7. Bridge Rectifier
   Material: Silicon semiconductor encased in epoxy resin
   Function: Converts high-voltage AC (120/230 V) into low-voltage DC current suitable for the LEDs
   Manufacturing Technique: Die fabrication
8. Electrolytic Capacitor
   Material: Aluminum can, electrolyte inside, plastic sleeve
   Function: Stores and releases energy, stabilizes DC voltage, and reduces flicker in the LED output
   Manufacturing Technique: Foil etching and forming, winding, can sealing
9. Two Screws
   Material: Steel
   Function: Secure the LED board to the central housing
   Manufacturing Technique: Cold heading, thread rolling, electroplating

Dissassemble Process

1. Shade Removal
   • The outer diffuser shade was detached from the housing by carefully bending and pulling it by hand.
   • Since the parts were friction-fit and bonded with a rubber-like adhesive, removal caused minor cracking and shattering of the plastic.

2. Unscrewing the Fasteners
   • A screwdriver was used to remove the two screws securing the LED panel to the housing.

3. LED Panel Removal
   • Pliers were inserted into the screw holes on the LED panel to grip, peel, and pull the panel away.
   • The panel was also partially glued to the housing, requiring additional force to separate it.

4. Metal Base Removal
   • A utility knife was tapped along the edge of the steel screw base to gradually break the seal.
   • Once loosened, the steel shell was peeled back and separated from the plastic housing.

5. Circuit Board Removal
   • Pliers were used to extract the driver PCB, which was loosely friction-fit inside the central housing.

6. Electronic Component Removal
   • Pliers were also employed to detach the remaining electronic components from the PCB.

Interesting Takeaways

1. Slotted Plastic Housing for Circuit Board Alignment
   The central plastic housing features tapered slots that transition from larger openings to narrower channels. This geometry guides the circuit board into position during assembly while ensuring that the board is securely held in place by friction fit. This approach reduces the need for additional fasteners, simplifying assembly and lowering manufacturing costs, also ensuring adequate retention during the lightbulb’s operational lifespan.

2. Use of a Metal Screw Base with Crimped Attachment
   Another notable design choice is the crimped interface between the metal screw base and the plastic housing. Instead of adhesives or screws, the base is mechanically deformed around the housing to create a strong, permanent connection. This ensures mechanical durability and also streamlines high-volume manufacturing, minimizing part count and assembly time.