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Overview&#;
1&#;What is COB Led?
2&#;What are the advantages of COB light source?
3&#;Where are the main applications of COB?
4&#;Why choose the COB?
5&#;How to choose LED COB lights?
6&#;Difference between COB LED and SMD LED
W
hat is COB Led?
COB lamp is a kind of LED lamp. COB is the abbreviation of Chip on Board in English, which means the packaging technology of chip on board. It is a high-efficiency integrated surface light source technology in which multiple LED chips/bare chips are directly attached to a high-reflectivity mirror metal substrate (such as silicon carbide). This creates a large LED chip with compactness, energy-saving, and excellent uniform brightness, which is loved by related professionals such as filmmakers and photographers. Generally, COB chips have 9 or more diodes. However, no matter how many diodes there are, COB LED lights have a single circuit with several contacts. Because it has the characteristics of easier dimming and color adjustment, high brightness, anti-glare, and can well solve the problems of chromatic aberration and heat dissipation, COB light sources have now been widely used in commercial lighting and other fields.
W
hat are the advantages of COB light source?
1&#;Cost saving
In terms of cost, compared with previous discrete light sources, COB light source modules can save the cost of device packaging in actual lighting applications, as well as the cost of light engine module production and the cost of secondary light distribution. In a lighting system with the same function, the overall cost can be saved by about 15%.
2&#;Strong performance
In terms of performance, the COB light source module can also effectively solve the glare problem caused by the combination of discrete light source devices through reasonable design and technology. You can also add a red chip combination to ensure that the efficiency of the light source is not reduced, and the life of the used equipment is guaranteed, while also improving the color rendering of the light source. The COB light source is integrated by multiple diodes, with a large focus area, a single chip can cover a large area, and the light concentration is high. The use of transparent lenses reduces light loss, improves clarity, and helps improve light efficiency.
3&#;Convenient application and mass production
In the actual application process, COB light source modules can also make the installation and production of lighting manufacturers easier and more convenient. With the current level of technology and advanced equipment, large-scale COB light source module production can be carried out.
4&#;Energy saving and environmental protection
Compared with other LEDs, the light-emitting area of the COB light source consumes less energy when emitting the same lumen brightness. The light-emitting area of the COB light source is greatly reduced, and the heat generated is greatly reduced. At a certain temperature, the life span and reliability will be improved, energy consumption will be saved, and the problem of light source failure due to heat dissipation will be avoided.
5&#;Secondary light distribution can be formed
The light-emitting angle and effect of the COB light source are better used through the refraction of the lens and the illumination of the spotlight&#;so that the light-emitting angle can be adjusted arbitrarily to form a secondary light distribution.
W
here are the main applications of COB?
LED COB is suitable for various outdoor and indoor lighting applications. It can be applied to general lighting in the industry, housing, construction and other fields. Its uniform brightness makes it play a vital role in film production and photography.
1&#;Indoors&#;spotlights, downlights, ceiling lights, fluorescent lights, and light strips.
2&#;Outdoors&#;street lights, high bay lights, floodlights, current city night scene wall washer lights, luminous characters, etc.
W
hy choose the COB?
1. High light efficiency
The high intensity and uniform luminosity of the on board chip can provide users with a good experience. COB LED lights are high-quality light emitters because they use reflectors to produce concentrated and regulated light. It satisfies high-standard lighting applications for brighter and clearer lighting.
2. Flexibility
The compactness of the COB LED array makes it easy to use in different places. Traditional DIP lamps are cheap but too bulky. Compared with DIP lamps, COB LEDs are more portable and flexible in outdoor applications and are very convenient.
3. Easy to install
Compared with the SMD lamp, the entire chip of the led cob panel only needs one circuit and two contacts, while the SMD lamp needs one circuit for each diode contained in the chip, so it is easier and more convenient to install.
H
ow to choose LED COB lights?
To choose a COB LED panel, the following are some of the factors you need to pay attention to.
1&#;Light output: The light output is determined by the lumens of the light. The higher the lumens, the brighter the light can be seen.
2&#;Lighting method: There are various COB LED lights on the market now. Some of them can change the lighting mode according to the different requirements of the scene.
3&#;Power supply: Before buying a lamp, it is necessary to determine its power requirements. If the lamp is portable, a stable power source is required.
4&#;Internal heat sink: Since the cob-led chip generates a lot of heat, a good heat sink is essential.
D
ifference between COB LED and SMD LED
Table form:
COB LED
SMD LED
Output lumen
(lm/watt)
At least 80 lm/w
50 to 100 lm/w
Mounting difficulty
Easy
Moderate to Hard
Efficiency
Higher
Lower
External Power Supply
External power supply with high current capability is must
Lower current capability is required
Cost
Expensive
Slightly lower than Cob led
Different inside the chip
two contacts and one circuitry, cannot be used to make color-changing lamps. To achieve a discolored appearance, multiple channel modifications are required.
red, green, and blue diode. By using these three diodes, any desired hue can be generated simply by changing the output level
Image form:
At present, lighting technology continues to develop. As designers realize the advantages of using COB LEDs over traditional standard LED options, COB LEDs are used more and more. In order to provide brighter light and use less energy, it has become a common application in lighting products. They can pack more LED light sources into a smaller space to increase lumen output, and can more effectively transfer heat to the radiator. Because of the simpler structure, the failure rate is lower, the light loss is lower, and the viewing angle is larger. It is difficult not to consider them in any lighting application design.
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Articles you may also be interested in&#;
At present, the commonly used encapsulation materials for LED electronic components mainly include epoxy resin, silicone, and other materials with high transparency. Epoxy resin has become the mainstream material of low-power LED packaging because of its excellent bonding performance, electrical insulation, dielectric performance, low cost and easy molding. But for power LED and printed circuit boards, congenital defects such as strong moisture absorption, easy aging, poor heat resistance and impact resistance of epoxy resin directly affect the service life of LED, and the color change under high temperature and short wave light directly affects the luminous efficiency. It is far from meeting the requirements of packaging materials in terms of high refractive index, low stress and high temperature aging resistance, so it is not suitable for power LED packaging materials.
High-performance silicone potting compounds and encapsulation materials have a series of excellent properties, such as high light transmittance, low internal stress, excellent high and low-temperature resistance, moisture insulation, UV and ozone aging resistance, good hydrophobicity and electrical insulation, and have widely become an ideal choice for LED potting and encapsulation applications materials.
Performance requirements of LED
encapsulation
materials
Different encapsulation forms require different materials. In recent years, LED has been developing in the direction of high power, high energy efficiency, high brightness and high reliability. This puts forward higher requirements for the optical properties, mechanical properties, aging resistance and construction properties of silicone potting and encapsulation materials. Good optical properties can ensure that LED light can be output more effectively, and good mechanical and adhesive properties can make LED chip-sensitive components better protected. Good aging resistance can prolong the service life of LED, and good construction performance can improve encapsulation compound efficiency.
Characteristics of silicone materials
Silicone materials are a kind of polymers with Si-O-Si bond as the main chain and side chains connected with various organic groups through silicon atoms.
Silicone materials have the dual characteristics of both organic polymers and inorganic materials, with high bond energy (452KJ/mol), large bond length (0.165nm), bond angle (109) of Si-O bond, low rotational hindrance of Si-O bond and good flexibility of chain segment, good thermal conductivity.
These inherent properties make silicone rubber materials have a series of excellent chemical resistance properties for protecting electrical components: excellent high and low-temperature resistance, which can work in the temperature range of-50 &#;-250 &#;; excellent aging resistance (heat resistance, ultraviolet resistance, ozone aging resistance), with several decades of service life in the natural environment; good hydrophobicity, surface energy as low as 21-22mN/m2; high light transmittance and very low internal stress; excellent electrical insulation for radiator leak sealing applications, good flexibility for vibration isolation applications, etc.
What is the classification of silicone encapsulant
m
aterials
Silicone encapsulant materials can be divided into two categories: low refractive coefficient and high refractive coefficient according to their use. in some special applications, there will be medium refractive coefficient products between them.
The refractive index of encapsulation materials with low refractive coefficient is 1.40 ~ 1.45, most of them are silicone methyl encapsulant materials, and the refractive index of high refractive coefficient silicone packaging materials is 1.50 ~ 1.55, most of which are phenyl silicone packaging materials.
However, due to the large difference between the refractive index of the silicone packaging adhesive with a low refractive coefficient and the refractive index of the chip, part of the light is fully reflected back into the chip, affecting the light output.
At present, the preparation of phenyl-containing vinyl polysiloxane and hydrogen-containing polysiloxane to obtain high refractive index encapsulation materials is one of the more mature and widely used methods. Silicone high refractive encapsulation materials generally use a two-component addition vulcanization system.
What is the curing principle of silicone encapsulant
Generally, the curing principle of silicone encapsulant material is to use vinyl silicone resin or silicone oil as the base glue, Si-H containing silane oligomer as the crosslinking agent, and platinum complex as the catalyst to form the encapsulant elastomer resists weathering, high or low temperatures, thermal shock and so on. The addition crosslinking room temperature curing reaction occurs between Si-CH=CH2 and Si-H of silicone polymer under the action of the catalyst.
Addition reaction equation
What is the composition of silicone encapsulant
Silicone potting and encapsulation raw materials are two-component colorless and transparent liquid substances. Component a generally includes base glue, catalyst and tackifier, and component B generally includes base glue, crosslinking agent and inhibitor. A small amount of reinforcing filler and pigment can be added according to the use situation.
1. Base glue
It is mainly an R-vinyl silicone resin / R-vinyl silicone oil, which provides vinyl groups that can participate in the reaction. R groups can be methyl, phenyl, tetrachlorophenyl and aminopropyl, etc., which are endowed with different packaging characteristics by connecting different groups.
Common synthesis methods mainly include functional siloxane hydrolysis condensation method, cyclosiloxane anionic ring-opening polymerization method, siloxane catalytic equilibrium method, etc. vinyl silicone oil or silicone resin can also be prepared by cationic polymerization with acid catalysts such as trifluoromethane sulfonic acid and cation exchange resin.
It is generally a low-viscosity hydrogen-containing silicone oil (such as XJY-702 Methylhydrosiloxane, Dimethylsiloxane Copolymer series) or silicone resin (such as XJY- vinyl MQ silicone resin), by controlling the molecular weight of hydrogen-containing silicone oil and functional group distribution and active hydrogen content and distribution, which can improve the performance of silicone encapsulation materials. The commonly used synthesis methods of hydrogen-containing silicone oil are generally hydrolysis condensation or cationic ring-opening polymerization under acidic conditions.
3. Catalyst
In this type of reaction, the catalyst is mainly used to catalyze the addition reaction of vinyl and active hydrogen to fast curing, and complexes such as platinum and palladium are generally used as catalysts. Among them, platinum-based catalysts with higher catalytic efficiency have a high catalytic effect at a concentration of 10-100 ppm.
However, silicone materials for LED encapsulation have high requirements for transparency and catalytic activity. At present, there are kinds of literature showing that the Karstedt catalyst and Speier catalyst are due to the use of tetramethyltetravinylcyclotetrasiloxane, tetramethyldivinyl Ethyl disiloxane, methyl vinyl phenyl cyclopolysiloxane or isopropanol solution are used as coordination solvents, which increase the compatibility with silicone resins and improve the overall performance, and have become the current silicone packaging materials. The most commonly used synthesis catalyst.
4. Inhibitors
Although the amount used in the reaction system is very small, it plays a crucial role in improving the storage stability of the reaction system, inhibiting the hydrosilylation reaction, and preventing excessive crosslinking. Commonly used inhibitors include ethynyl cyclohexanol, triphenyl propargyl alcohol, heavy metal ion compounds, 6-12-membered cyclic siloxane oligomers containing olefin groups, and benzotriazoles.
Ethynyl cyclohexanol
Triphenyl propargyl alcohol
5. Tackifier
Because there are no reactive groups on the surface of the substrate, ordinary addition-type silicone materials have little adhesion to the substrate. In order to maintain good sealing between the packaging material and the LED device, the packaging material must have good adhesion to the LED bracket and the bottom plate material. A common solution is to introduce tackifiers into LED packaging materials. Commonly used tackifiers include silane coupling agents and silane coupling agents modified (containing epoxy, acryloxy and vinyl) polysiloxanes. A large number of experiments have confirmed that the silicone tackifier modified by the silane coupling agent can greatly improve the bonding and sealing performance with the substrate without affecting its transparency and mechanical properties.
Polysiloxane tackifier modified by silane coupling agent
6. Reinforcing fillers
There are mechanical property issues with traditional two-component addition silicone materials, thus it requires reinforcing filler to meet the mechanical properties of packaging materials.
Commonly used reinforcing fillers mainly include fumed silica and MQ silicone resin, etc. For the special requirements of LED packaging materials for transparency, currently, the most commonly used silicone packaging material reinforcement filler is MQ silicone resin with good compatibility with the system. MQ silicone resin is a kind of silicone resin containing both monofunctional Si-O chain unit (M) and tetrafunctional Si-O chain unit (Q). MQ silicone resins such as vinyl MQ silicone resin and hydrogen-containing MQ silicone resin have good compatibility with the silicone packaging material system for LEDs and the reinforcement effect is obvious.
With the continuous improvement of power and brightness and the rapid development of white LEDs, silicone encapsulation materials have advantageous over EP encapsulation materials. Among them, high-refractive-index silicone packaging materials will be ideal matrix resin for high-power LED packaging. With the continuous breakthrough of technical barriers, the application scope of high-refractive-index silicone packaging materials will continue to expand, and many domestic LED lighting manufacturers will promote and apply it.
XJY Silicones&#;First choice silicone raw material supplier of potting compounds
and encapsulation materials
XJY Silicones, one of China's leading silicone MQ resin manufacturers, has 30+ years of R&D and manufacturing experience and 15+ related patents in the silicone industry, also can customize the products according to your potting and encapsulating applications requirements.
Methyl Vinyl VMQ silicone
Cross-linking agent: Hydrogen-containing silicone oil
The company is the world’s best Low Refractive Index Silicone For Cob Led Encapsulation supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.