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Two boards in an LED bulb: the MCPCB LED board and the driver PCB
Open a typical LED bulb and you find two printed circuit boards: a round aluminium board that carries the LEDs, and a small board that carries the driver. Some bulbs combine both on one board. This guide explains each board, the material it uses and the sizes we already have tools for.
Sara Circuits team · 24 October 2026
Board 1: the LED board (aluminium MCPCB).
The LEDs sit on a round aluminium MCPCB: one copper layer on a thin dielectric over an aluminium base. The metal base takes heat from the LEDs and spreads it out, so the LEDs run cooler and keep their brightness longer than on paper or glass-epoxy boards.
- Thickness: 0.8 mm to 1.6 mm
- Copper: 35 µm standard, 70 µm where the design needs it
- Solder mask: white, which reflects light back out of the bulb; green and black on request
- Finish: HASL or OSP, to keep pads solderable for your SMT line
- Ready dies: 38, 39.8, 44.6, 45 and 46.4 mm, 40/46 mm, 53 mm, 60/66 mm and 62 mm
Board 2: the driver board.
In bulbs with a separate driver, the driver sits on its own small single-sided board. Driver boards usually run on CEM1; CEM3 suits hotter drivers in closed housings. We punch the common driver strip sizes, 17 × 34 mm and 17 × 40 mm, on ready dies.
Because the driver carries mains, spacing matters. Tell us the creepage your product standard needs; our CAM team checks every gap before we quote. LED driver PCB
Or one board: DOB.
A DOB (Driver On Board) puts the driver and the LEDs on one aluminium board. It removes the separate driver board, but the aluminium board now carries mains, so creepage must be kept to your standard on the same board. Our ready dies for DOB boards are 82, 112 and 132 mm. DOB PCB
Emergency and rechargeable bulbs.
Emergency and rechargeable bulbs use an LED board plus a charging and changeover board. The 40/46 mm, 60/66 mm and 62 mm sizes are in regular production. Emergency bulb PCB
Which boards for which bulb.
| Bulb type | Boards | Usual material |
|---|---|---|
| LED bulb with separate driver | Round LED board + driver strip | Aluminium MCPCB + CEM1 (CEM3 for hotter drivers) |
| DOB bulb | One round board with driver and LEDs | Aluminium MCPCB |
| Emergency / rechargeable bulb | LED board + charging and changeover board | Aluminium MCPCB + CEM1 or CEM3 |
| Panel, batten, street light | LED board + separate driver | Aluminium MCPCB + CEM1 or CEM3 |
A starting point: we confirm the material after reviewing your design.
Design tips that improve yield.
- Use the LED maker's recommended pad footprint. Undersized pads cause tilted LEDs and dark spots after reflow.
- Keep thermal pads large and copper continuous under the LEDs to spread heat into the aluminium.
- On punched boards, keep holes at least one board thickness from the outline so edges do not crack.
- Keep copper back from the outline; copper at the edge can lift or burr during blanking.
- Design to a ready die size where you can. A match means no tooling charge and no tool lead time. Ready dies
Both boards from one plant.
We make the aluminium LED board, the CEM1 driver strip and DOB boards under one roof at Barwala, Haryana, so both boards in a fitting can come from one supplier, on one quote. Production starts at 40 m² per design; see what that means in pieces.
Questions? Answers.
How many PCBs are in an LED bulb?
Usually two: a round aluminium MCPCB for the LEDs and a small driver board, often CEM1. A DOB bulb uses one aluminium board for both.
What material is an LED bulb PCB?
The LED board is aluminium MCPCB with white solder mask. The driver board is usually CEM1, or CEM3 for hotter drivers.
Do you make both the LED board and the driver board?
Yes. We make MCPCB LED boards, driver strips and DOB boards at our plant in Barwala, Haryana. We supply bare boards for your SMT line; we do not assemble the LEDs.
Which LED bulb PCB sizes do you have dies for?
Round LED boards from 38 mm to 66 mm, DOB boards at 82, 112 and 132 mm, and driver strips at 17 × 34 and 17 × 40 mm. All 21 ready dies
Related: LED bulb PCB · LED driver PCB · DOB PCB · LED PCB manufacturer · Aluminium PCB (MCPCB) · MCPCB full form · All guides & news
Send us your design.
Attach the Gerber, tell us the material and quantity, and we will come back with a price.