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COB LED vs SMD LED vs DOB LED: LED PCB Assembly and Design Solutions

PCBONLINE Team

Fri, Feb 25, 2022

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COB LED lights are much more expensive than SMD LED lights, do you know why? And in the LED market, you have a new product option, DOB LED, what is that? PCB is the core of LED products. You can find answers to these questions from LED PCB manufacturing. In this post, the LED PCB manufacturer PCBONLINE gives a brief introduction to COB LED, SMD LED, DOB LED, and the differences between them.

Part1: What is COB LED

  • Features of COB LED: high thermal generation, small areas for thermal dissipation; evenly-shed light, no halo; LEDs are bonded on PCB

COB or chip-on-board is an LED chip package, in which multiple LED chips are integrated and bonded to the PCB and then sealed with glue. On the PCB board, you will notice that COB LEDs are placed altogether. When you use COB LED products, you will find that the light is shed evenly without the halo.

In PCBONLINE's LED PCB assembly factory, COB LED bonding can be achieved in two different methods - wire bonding and flip-chip bonding.

COB LED bonding

LED PCB wire bonding: the LED chip is connected with the PCB using a gold or aluminum wire, and then the chips are sealed by glue.

LED PCB flip-chip bonding: the P-N junction of the LED chips is directly bonded with the PCB without any gold or aluminum wires. Compared with wire bonding, the chips are flipped.

Is COB LED bonding restricted by the PCB substrate materials? No, as long as your PCB design can handle thermal management. From PCBONLINE, you can have COB LED chips bonded on ceramic substrate PCBs, FR4 PCBs, aluminum PCBs, flexible PCBs, and homogeneous clear flex PCBs. If you have trouble with thermal management, we can offer PCB design assistance for free.

Wire bonding COB LED PCBs are usually used for small-power LED lights, while flip-chip bonding COB LED PCBs are designed for high power devices. You can see the ceramic COB LED PCBs we make for spotlights, which can work continuously for more than 10 hours per day.

ceramic LED PCB

Part 2: What is SMD LED

  • Features of SMD LED: low requirements for thermal management; unevenly-shed light, having halo; SMT assembly

SMD LEDs are LED products whose LED PCBs are assembled using surface-mount assembly technology. In the LED market, SMD LEDs are the most common type because they are the cheapest. Unlike COB LEDs, the SMD LED chips spread on the PCB board, so the thermal dissipation requirement is lower than COB LEDs. But because the LED light sources are spread, the light shedding is uneven and has halos.

SMD LED PCB board

During LED PCB assembly, SMD LEDs are picked and placed on corresponding PCB pads and then go through the reflow soldering oven and AOI testing machine. But SMD LEDs are mounted in an LED SMT machine that is specifically used for SMD LED assembly.

Like COB LEDs, SMD LED assembly is not restricted by PCB substrate materials. You can order SMD LED PCBs with any substrate from PCBONLINE, such as aluminum PCBs, FR4 PCBs, ceramic PCBs, flexible PCBs, etc.

Part 3: What is DOB LED

  • Features of DOB LED: power source AC replaces AC/DC; high LED power efficiency; long lifespan

DOB stands for driver-on-board, and it should be noted that DOB LED is not an LED chip assembly technology but an LED PCB design option. The LED and IC chips are directly powered by utility power (110V or 220V). DOB LED circuit design leaves out electrolytic capacitors, inductors, transformers, and this design reduces the LED product size.

In recent years, electronic component prices have been rising. The DOB LED PCB solution reduces the PCB parts and you can spend less on BOM materials for LED products.

If you made DOB LED designs, or if you want PCB design or engineering assistance, please contact PCBONLINE to offer free DOB LED PCB design assistance and one-stop PCB manufacturing.

Part 4: COB LED vs SMD LED vs DOB LED

What are the differences between COB, SMD, DOB LEDs?

First, COB LED and SMD LED are two LED chip assembly technology, while COB LED is an LED PCB design solution.

Second, COB LEDs are integrated and bonded on the PCB board; SMD LEDs are scattered and surface-mounted on the PCB board; COB LEDs are not integrated, and the power source is AC utility power.

Third, COB LEDs have higher power than COB LEDs and SMD LEDs.

Four, COB LEDs have no halo, and their light shattering is homogeneous; SMD LEDs have haloes and uneven lighting; DOB LEDs lighting is not as even as COB LEDs, but better than SMD LEDs.

Five, usually, SMD LEDs are the cheapest among the three LED products, and DOB LEDs are more expensive than COB LED PCBs.

Quality COB, SMD, DOB LED PCB Manufacturing and Assembly

If you plan to have LED PCBs manufactured and assembled, you can contact PCBONLINE. If you do not have LED PCB designs, we can offer our off-the-shelf solutions for free and complete one-stop manufacturing, and send ready-to-use LED end-products to you.

LED PCB manufacturing

PCBONLINE, founded in 1999, has two large advanced PCB manufacturing bases in Jiangsu and Jiangxi, as well as one PCB assembly factory in Shenzhen. For the past 23 years, we've manufactured thousands of LED PCB orders, including COB LEDs, SMD LEDs, DOB LEDs.

Here are the reasons for you to co-operate with PCBONLINE in LED PCB manufacturing:

    • PCB half-holes and gold fingers are one of our PCB manufacturing advantages.
    • PCBONLINE can provide LED PCBs with any substrates, such as aluminum, FR4, ceramic, copper, polyimide, glass.
    • We have rich experiences in COB, DOB, SMD LED PCB design, manufacturing, and assembly.
    • ISO 9001, IATF 16949, UL, REACH, RoHS-certified LED PCB manufacturing and assembly quality management.
    • Quality LED chips and other components co-procurement with other large EMS from component factories.
    • Free one-on-one LED PCB design assistance, free complete PCBA sample for batch production.

If you have any LED PCB needs, please send your Gerber/IPC 2581 files or any inquiries to PCBONLINE by email at info@pcbonline.com.

Conclusion

COB LED and SMD LED are two different technologies to assemble LED chips on PCB boards, while the relatively new COB LED is a PCB design solution that uses utility power to drive rather than AC/DC transformers. COB, SMD, DOB LED product development is not restricted by PCB substrates. If you want COB, SMD, DOB LED PCB design, manufacturing, and assembly, please do not miss the 23-year old source factory PCBONLINE.


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