What are the disadvantages of COB LED strips?

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What is Dotless LED strip, or COB?

COB stands for Chip on Board, meaning the LED chip is directly packaged onto a printed circuit board (PCB). In flexible strip lighting, "Chip on Board" technology offers a simplified approach to LED design.

A standard SMD (Surface Mount Device) LED includes a chip holder (bead) with the actual LED chip inside, covered by a phosphor coating.

The COB-LED strip design eliminates the unnecessary elements, leaving only the LED circuit, the yellow phosphor overlay, and the junction.

COB VS SMD LED strip lighting

1. The COB LED strip has a 180-degree beam angle, while the SMD LED strip has an 110-degree beam angle.
2. COB LED strips are more flexible than SMD LED strips.
3. The COB LED strip offers a steady, continuous light.
4. The COB circuit is directly attached, with no gold wire, unlike SMD LED strips which have gold wire.

How is COB LED strip made?

1. Preparation of printed circuit boards
2. Chip printing on PCB
3. Resistor printing on PCB
4. "Reflow" process at 65 degrees to combine components
5. Applying the fluorescent layer onto the LED strip
6. Baking the COB LED strip
7. Testing and packaging the LED strip light.

Advantages and disadvantages of COB LED strip

Now that you have an understanding of the technique, let's explore the pros and cons of both approaches.

Advantages of COB LED strip lighting

Dotless LED strip, COB LED strip.

One of the major desires for traditional LED strips is eliminating visible dots. With COB technology, this is achievable because light points can be set up to 840 meters below a flat layer, rendering the dots invisible. The light is softer and steadier, appearing as a continuous source of illumination rather than separate points.

SMD LED strips (CRI 90) feature fewer and larger diodes. Traditional market LED strips have 30-60 LEDs per meter, clearly displaying each light point. SMD strips with 240 LEDs per meter (like LedStore EQUAL) exist but require efficient cooling due to the heat generated by the SMD diodes. Dots are always visible in SMD LED strips.

With 840 LEDs per meter in a COB strip, it’s challenging to detect individual LED dots. Only if the strip is dimmed to 1-5% and viewed closely is a single LED visible. This makes COB LED strips ideal for:

• Exposed fixture surfaces
• Illuminated surfaces under 60cm from the LED strip (e.g., shelves)
• Reflective surfaces, like stone or glass
• Installations requiring a neon effect (RGB versions)

More flexibility

Due to the small size and even distribution of diodes, COB LED strips are far more flexible than traditional LEDs. The diodes' proximity ensures no part of the strip is misaligned, even at corners. This flexibility simplifies installation, as there's no need to worry about breaking the circuit at sharp angles.

More stable, fewer problems

COB LED strips consist of a single long chip attached directly to the PCB, avoiding issues caused by thin gold wires in traditional SMD LED strips. These wires can easily break from excessive heat.

The COB LED strip design features three circuits in parallel, forming a cut-off distance of 2.5m-10cm. Even if two circuits fail, the strip continues to light, ensuring no dark areas. With up to 840 LEDs per meter, the strip remains visually continuous even if a few circuits fail.

In traditional SMD LED strips, a single faulty circuit results in a completely dark section of the segment.

Wide beam angle

SMD strip lights have a 110-degree beam angle, while COB strips offer a 180-degree angle. The installation profile can influence the final beam angle in both cases.

The weaknesses of COB LED

Difficult to maintain color consistency

Since COB-LED strip manufacturing machinery is not widely available, ensuring color uniformity is challenging. 100% compliance within a 3-phase color tolerance is hard to achieve, making quality control crucial. Producing high-quality dot-free LED strips is not straightforward.

Lower light output

The luminous efficacy of COB LED strips is around 120 Lumen/Watt. For higher light output, SMD LED strips are better, reaching up to 200 Lumen/Watt, with the most common output between 100-150 Lumens.

Lower maximum power

The recommended maximum power for COB LED strips is 15 W/m. Higher power would generate excess heat, reducing the strip's lifespan.

Dotless LED strip light – COB LED features

By now, the advantages and disadvantages of COB LED strips should be clear. Let’s delve deeper into their specific features. If you're familiar with LED strips, many points will ring a bell, but COB LEDs have certain distinctions from traditional types.

Cut and paste

COB LED strips can be cut like any other LED strip at specific intervals (25, 42, 50 mm). This allows for size adjustments or project-specific installations. Cut strips can be reused and joined by soldering. Quick connectors are available but might not fit all profiles or maintain durability.

Dimmable

The dotless LED strip can be dimmed similar to standard SMD strips using Triac, PWM, or 0-10V dimming power supplies. RGB, CCT, and RGB+CCT strips require control electronics, commonly using Zigbee or DALI2 technologies.

Color options

White light: Available in 3000K, 4000K, and custom temperatures.
Colored light: Available in RGB, usually with a white light option.
Adjustable white light: CCT ranges between 2500-6500K.

SUMMARY FAQ

What is a COB-LED strip light?

COB LED strip or COB LED tape uses LED chips directly attached to a PCB (Flexible Print Circuit Board), providing continuous and dot-free light.

How do COB-LED strips work?

The LED chip is mounted on the PCB and covered with a fluorescent layer serving as a diffuser. Their high chip density, exceeding 800 chips per meter, ensures excellent illumination.

Do COB-LED strips heat up?

A standard 7.2W COB LED strip does not get very hot, averaging around 40 degrees Celsius.

How long does a COB LED strip last?

Approximately 50,000 hours.

Are COB-LED strips brighter?

Generally, COB LED strips are not as bright as SMD LED strips. CRI98 COB strips offer about 100 Lumen/W, while SMD strips can go up to 150 Lumen/W. LedStore’s SMD strips focus on longevity and high color rendering (above CRI 90), not maximum output.

Can COB LED strips be cut?

Yes, COB LED strips can be cut at marked intervals.

Are COB-LED strips more efficient?

No, COB strips have lower luminous efficacy than SMD strips, typically around 100 LM/W compared to up to 150 LM/W for SMD.

Some other LED light articles related to the topic:

Choosing transformers – to the article
Shorter article about choosing an LED strip - article
For a longer article on LED strip lighting: - article
COB LED Wikipedia article (in English)

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Since 2010, LedStore has been a leading expert in LED lighting, designing state-of-the-art products with a focus on temperature control and high color rendering. We create around 500 lighting designs annually for our clients. Our services include custom-made LED strips and installations for everyone.

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