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DOB PCB design guide: driver and LEDs on one aluminium board
A DOB (Driver On Board) PCB carries the LED driver components and the LEDs on one single-sided board, usually an aluminium MCPCB. It removes the separate driver board from the bulb, but it also brings mains voltage onto the LED board. This guide explains what that changes in the layout, the material and the outline, and what we check before we quote.
Sara Circuits team · 25 October 2026
DOB vs a separate driver board.
| LED board + separate driver | DOB (driver on board) | |
|---|---|---|
| Boards in the bulb | Two: round MCPCB LED board + driver strip | One round board |
| Usual material | Aluminium MCPCB + CEM1 driver strip | Aluminium MCPCB (CEM1 for some low-wattage designs) |
| Mains voltage on the LED board | No (stays on the driver board) | Yes, next to the LED string |
| Ready dies at Sara Circuits | LED boards Ø 38–66 mm; driver strips 17 × 34 and 17 × 40 mm | DOB boards 82, 112 and 132 mm |
| What to watch | Two designs, two 40 m² minimums | Creepage and heat on one board |
Both routes are single-sided and both are made at our plant in Barwala, Haryana. Two boards in an LED bulb
1. Mains next to the LEDs: creepage first.
On a DOB the mains input, bridge and driver sit on the same aluminium board as the LED string. Every gap between a mains track and anything else has to meet the creepage your product standard needs.
- Tell us the creepage and clearance your standard requires. Our CAM team checks every gap against it and flags anything short before a panel is printed.
- Where space is tight, add a slot to stretch the creepage path. Draw it on your mechanical or outline layer; on a blanking die it is punched in the same stroke as the outline.
- Keep copper back from the board edge, especially on mains tracks. Spacing guide
2. Two heat sources on one board.
A DOB has two things that run warm: the LEDs and the driver IC. The aluminium base spreads heat from both, but the layout has to let it.
- Keep LED thermal pads large and copper continuous under and around each LED.
- Give the driver IC its own copper area instead of squeezing it between LEDs.
- Use 35 µm copper as standard; 70 µm is available where the design needs it.
This is why most DOBs are aluminium MCPCB. Aluminium PCB vs FR4
3. MCPCB or CEM1?
Aluminium MCPCB is the material for most DOB boards, because of the heat from the LEDs and the driver. CEM1 suits some low-wattage designs. We confirm the material after reviewing your files. MCPCB Material guide
4. Pads from the datasheets.
Use the footprints recommended by the LED maker and the driver IC maker. Undersized pads are a common cause of tilted LEDs and dark spots after reflow. White solder mask is standard on DOB boards because it reflects light back out of the fitting; green and black are available.
5. Design to a ready outline.
Our ready blanking dies for DOB boards are 82 mm, 112 mm and 132 mm, part of a library of 21 ready dies. If your board matches, there is no tooling charge and no wait for a new tool. A new outline needs a new blanking tool, quoted separately.
| DOB size | Typical use | About pcs in 40 m² |
|---|---|---|
| 82 mm | Compact DOB and downlight boards | 5,900 |
| 112 mm | Mid-size DOB, the size most brands sell in volume | 3,200 |
| 132 mm | Large DOB and panel designs | 2,300 |
Pieces are based on diameter × diameter, the way our 40 m² calculator counts round boards. 40 m² in pieces Ready dies
What we check before we quote a DOB.
- CAM check of the Gerber: creepage on every mains gap, slots, LED and driver pads, copper near the edge, panel layout.
- Outline check against all 21 ready dies.
- PDF approval: you approve the final panel before any material is cut.
- Bare board testing of every lot, an independent QC check and dispatch with a job number, ready for your SMT line.
We supply bare DOB boards; we do not assemble components. DOB PCB manufacturer
Questions? Answers.
What is the full form of DOB?
Driver On Board: the LED driver components and the LEDs are on one board instead of two.
What material is used for DOB PCBs?
Aluminium MCPCB for most DOBs, with white solder mask. CEM1 suits some low-wattage designs. We confirm after reviewing your files.
Which DOB sizes do you have dies for?
Ready dies for 82, 112 and 132 mm DOB boards, plus other round sizes in our library of 21 ready dies. Ready dies
Do you check creepage on DOB boards?
Yes. Tell us the creepage your product standard needs and our CAM team checks every gap against it before a panel is printed.
Do you assemble DOB boards?
No. We supply bare, tested DOB PCBs from our plant in Barwala, Haryana, ready for your SMT line. Production starts at 40 m² per design.
Related: DOB PCB manufacturer · Aluminium PCB (MCPCB) · LED bulb PCB · LED driver PCB · Two boards in an LED bulb · 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.