In this article, we will discuss some of the questions that you are most concerned about COB LED module such as the differences between it and SMD LED module, and the advantages you can apply to improve your LED display project and bring more profits.
Also, we will involve some technical points of this module to help you better understand the features and structure!
Table of Contents
1. What Is COB LED Module?
1.1 Advantages
1.2 Disadvantages
2. Which Is better SMD or COB?
3. What Is Flip-Chip COB?
3.1 Why Flip-chip COB ?
3.2 How Flip-chip COB LED Improves the Industry Efficiency?
4. To Sum up
1. What Is COB LED Module?
COB refers to Chip on Board, which means the LED lighting-emitting chips will be directly mounted on the PCB board precisely. The light-emitting LED chips are connected to the driver components on the board through special media with high protection ability.
Although it sounds difficult to understand, simply put, COB LED display is to achieve 4K, even 8K, 16K large LED display screen better as it can break limitation of pixel pitch of SMD LEDs to achieve higher pixel density.
Within the range from 0.5mm to 3.3mm, there are COB (Chip-on-Board) small pixel pitch products available with increments of 0.1mm.
COB LED Module SMD LED Module
1.1 Advantages:
(1) Higher brightness with lower power consumption
Compared with SMD LED module and DIP LED module, COB LED module can achieve higher brightness with lower power consumption as its chips need less space.
(2) Excellent heat dissipation
The aluminum or ceramic substrate of COB LED chip features high efficiency of heat transfer. And also because of this feature, COB LED chips can be mounted tightly.
(3) Outstanding protection ability
Due to its coating technology, COB LED display can be protected from moisture, water, dust, UV rays, and impacts, meaning this kind of screen have high visual performance with strong protection performance and reliability.
(4) Supper lightweight
According to the actual needs of customers, PCB boards with a thickness ranging from 0.4 to 1.2 mm can be used to reduce the weight to at least 1/3 of the original traditional products, which can significantly reduce structural, transportation, and engineering costs for customers.
(5) Anti-impact and crush
The LED chip is directly encapsulated in the concave position of the PCB board, and then epoxy resin glue will cover them. The surface is smooth and hard, resistant to impact and wear.
(6) Wide viewing angle
The viewing angle can reach 175° to 180° with a better optical diffuse color muddy light effect.
(7) Long working time
The triple protection treatment ensures high resistance to water, dust, rot, electrostatic, oxidation, UV, and so on.
The module can work normally under temperatures between minus 30 degrees to 80 degrees.
1.2 Disadvantages:
(1) Higher price
COB LED screens are more expensive than SMD LED displays,
Compared with SMD LED display, COB LED display has obvious disadvantages. It has lower color uniformity, which may result in a poorer viewing experience. In addition, COB LED displays are also more expensive than SMD LED displays.
(2) More complex maintenance
Due to the requirement of specialized equipment, repairs are difficult and costly. In most cases, it is necessary to send the cabinets back to the factory for repairs.
(3) Poor consistency
Due to the absence of selecting LED lamp beads as SMD LED module, leading to poor consistency.
(2) Adaptability to small-pitch pixel LED displays
Most of the pixel pitch of SMD LED display is larger than 1.5mm. For example, P2.5, P3.91, P4.81, and so forth.
Due to the limitation of SMD packaging technology, it is not suitable for LED screen with pixel pitch smaller than 1mm, which is one of the most drawbacks of this type of LED lamp bead.
While COB LED module, can achieve finer pixel pitch such as P0.6, P0.9, and P1.2, which can break the limitation of SMD packaging to improve the pixel density directly. Thus, when it comes up to indoor HD screens, this module can be one of the wise choices.
(3) Failure rate
Conventional SMD-packaged LED screens have a relatively high dead pixel rate, often exceeding 1.3% (30 in a million).
This leads to frequent occurrences of dead or malfunctioning pixels, significantly increasing the need for after-sales service. Unfortunately, due to technological limitations, this issue has yet to be resolved.
On the other hand, COB-packaged LED screens do not require reflow soldering, which eliminates the risk of pixel detachment during the soldering process. As a result, COB packaging exhibits minimal dead pixel phenomena, greatly reducing the need for after-sales service.
(4) Production process
COB packaging technology is classified as non-packaged or minimally packaged, but it does not completely eliminate the packaging process.
Instead, it simplifies the packaging process compared to surface mount technology (SMT). COB packaging eliminates several steps, saving time, reducing complexity, and ultimately lowering costs.
The process can be:
Clean PCB
Apply adhesive drops
Chip placement
Testing
Encapsulation with black glue and heat curing
Testing
Storage in warehouse
In SMT production processes, steps such as die bonding, wire bonding, encapsulation, baking, stamping, color separation, tape bonding, and surface mounting are involved.
On the other hand, COB simplifies this process by directly attaching the IC chip to the circuit board, followed by die bonding, wire bonding, testing, encapsulation, and baking to create the final product.
2. Which Is better SMD or COB?
It is difficult to say which one is better, the answer depends on the user scenarios and customers’ requirements! Here we list some differences between COB LEDs and SMD LEDs.
| LED Type | COB LED | SMD LED |
| Brightness level | Higher | Less brighter |
| Quality of light | Surface light | Point light |
| Cost | Higher cost-efficiency | More Expensive |
| Electricity Consumption | More efficient | Less efficient |
(1) From production cost
As you can see from the chart, COB LEDs are more cost-effective than the other ones.
That is, the production process of SMD LED involved is more complex, resulting in relatively higher costs.
Additionally, there are increased costs associated with transportation, material storage, and quality control between the LED packaging factory and the screen manufacturing plant.
(2) From maintenance level
SMD packaging believes that COB packaging technology is too complex and its first-pass yield is not as controllable as individual LED lamp beads. The inability to repair failure points results in a low yield of finished products.
Moreover, If a COB module is damaged, it usually requires returning to the factory for repairs.
(3) By using scenarios
As we have mentioned before, COB LED module can bring higher pixel density to achieve super fine pixel pitch HD LED displays such as P0.6, P0.9 and P1.2 thus is suitable for close viewing distance and indoor LED screen!
3. What Is Flip-Chip COB?
COB packaging technology can be divided into front-mounted COB and flip-chip COB.
The main difference lies in the flip-chip COB technology, which eliminates the use of wire bonds and instead adopts a chip-on-board flip-chip packaging structure.
3.1 Why Flip-chip COB ?
Compared with front-mount COB, flip-chip COB has higher protection ability, finer pixel pitch, high color rendering, and more reliable surface-emitting light sources.
The module can be thinner and lighter and also has lower thermal resistance. What is more, the quality can be improved further.
In the future, flip-chip COB may be widely used in the Micro LED industry!
3.2 How Flip-chip COB LED Improves the Industry Efficiency?
Currently, many LEDs use gold wires to connect the PN junction of the chip to the positive and negative poles of the bracket in a wire-bonded packaging structure.
However, the increased output power consumption may cause wire breakage and cause problems of significant optical decay and light extinction.
However, Flip-chip COB can improve the issues of wire breakage and poor heat dissipation in wire-bonded packaged LEDs:
The inverted structure involves directly bonding the PN junction of the chip to the positive and negative terminals on the substrate using eutectic bonding, eliminating the use of bonding wires to minimize light extinction issues!
That is why flip-chip COB has a more advanced design.
4. To Sum up
In this article, we discuss the COB LED module from the aspect of the production process, production cost, advantages, and disadvantages.
Generally speaking, COB LED module can be used for fine pixel pitch LED display with pixel pitch even under 1mm. And the production process is easier than the SMD LED module. However, there are now still some issues such as more complex maintenance and
To further understand these concepts, we give detailed explanations for each point to help to discover the differences laying between COB LED and the prevailing one – SMD LED. If you still are not very clear about it, just read the post again as we have listed the main points already.
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