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SMD LED vs COB LED vs DOB LED - 3 Options for LED PCBs

COB LED
pcbonline PCBONLINE Team Fri, Feb 25, 2022
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SMD LED PCB assembly

What does SMD LED mean? What's COB LED? What's the full form of DOB in LED? This blog introduces SMD LED, COB LED, and DOB LED. You can also learn about SMD LED PCBs.

This blog gives an introduction to SMD LED, COB LED, and DOB LED, and the differences between them.

Part 1: What Does SMD LED Mean

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

SMD LED means surface-mount device light-emitting diode. They are common and cost-effective SMDs.

SMD LEDs are LEDs that are surface-mounted on PCBs. They have very short leads and are packaged in trays or tape/reels.

In SMT assembly, SMD LEDs are picked and placed automatically on an LED PCB, and then the LED PCBA is reflow soldered and accepts the automatic optical inspection. When installed with an enclosure, the PCBA becomes an SMD LED lamp.

SMD LEDs

In the LED market, SMD LED lights are the most common type because they are the cheapest.

SMD LED PCBs are the most affordable LED PCBs because of efficient SMT assembly, low-cost SMD LEDs, and cost-effective SMD LED PCBs.

Typical, the substrate material of SMD LED PCB is aluminum. Aluminum PCBs have 1 to 4 layers, and the PCB design is easy. Aluminum PCBs have a higher thermal conductivity (1W/mK to 9W/mK) than FR4 PCBs. From the one-stop PCB manufacturer PCBONLINE, the price of aluminum SMD LED PCBs is $39 per square meter.

Besides aluminum, from PCB manufacturer PCBONLINE, you have other options for the substrate material of SMD LED PCBs, such as FR4 and copper.

SMD LED PCB light

On the PCB board of an SMD LED light, the SMD LED chips scatter on the PCB board, so SMD LEDs can conduct heat quickly. SMD LED lights have a lower thermal dissipation requirement than the integrated way, which is COB LED introduced in the next part.

Overall, SMD LEDs are cost-effective and easy to assemble on PCBs, and their thermal dissipation is good. However, the SMD LED light sources are scattered, which causes halos and uneven light shedding of SMD LED lights.

Part 2: What's 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 mounting on PCB method. Multiple LED chips are integrated and directly bonded to the PCB and then sealed with glue.

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

COB LED bonding

  • LED PCB wire bonding: the LED chip is connected to 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.

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.

On a COB LED PCB board, you will notice that COB LEDs are placed together in a rounded or regular polygon shape.

When you use COB LED products, you will find that the light is shed evenly without a halo. This is because the LED light source is integrated.

ceramic LED PCB

The integrated arrangement of COB LEDs generates a lot of heat when working. So the thermal dissipation requirement of COB LEDs is high. When you design a COB LED PCB, thermal management is the top consideration.

By choosing a substrate material with high thermal conductivity, designing the OCB LED PCB to be single-layer or double-layer with two component mounting sides, or adding copper busbars to the PCB, you can do well in the thermal management of COB LED PCBs.

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 PCBs, FR4 PCBs, aluminum PCBs, flexible PCBs, and even clear flex PCBs. If you have any doubts about thermal management, PCBONLINE can offer PCB design assistance for free.

Part 3: What is the Full Form of DOB in LED

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

The full form of DOB is driver-on-board. It means other electronic components and LEDs are assembled and work together on the PCB. 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, and 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, and DOB LEDs?

First, COB LED and SMD LED are two LED chip assembly technologies, 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.

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

Fifth, 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 the LED PCB source manufacturer PCBONLINE.

If you do not have LED PCB designs, PCBONLINE can offer 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, PCBONLINE has manufactured many LED PCB orders, including COB LEDs, SMD LEDs, and DOB LEDs, for automotive, industrial, medical, agricultural, and consumer LED lighting applications.

Here are the reasons for you to cooperate with PCBONLINE in LED PCB manufacturing:

    • One-stop EMS electronic manufacturing for SMD LED PCBs, COB LED PCBs, and DOB LED PCBs.
    • PCBONLINE can provide LED PCBs with any substrates, such as aluminum, FR4, ceramic, copper, polyimide, and glass.
    • We have rich experiences in COB, DOB, and 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 can join component co-procurement with other large EMS from component factories.
    • Free one-on-one LED PCB design assistance and complete PCBA sample for batch production.

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

Conclusion

COB LED and SMD LED are two different technologies for assembling 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, and DOB LED product development are not restricted by PCB substrates. If you want COB, SMD, or DOB LED PCB design, manufacturing, and assembly, please do not miss the 23-year-old source factory PCBONLINE.


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