CN103531693B - A kind of preparation method of the COB area light source of big lighting angle - Google Patents

Abstract

The invention discloses a method for preparing a COB surface light source with a large luminous angle, which comprises the following steps: electrically connecting an LED chip with a substrate, preheating the substrate, mixing an organic silicon resin encapsulating material for the LED with a yellow fluorescent powder, and then Put the mixed material on the preheated substrate by vacuum dispensing, and after heating and curing, a COB surface light source with a large luminous angle is formed. The silicone resin encapsulation material for LED consists of the following vinyl silicone oil with a mass percentage of 40-75%, 15 ～45% hydrogen-containing silicone oil, 0.1～0.5% platinum catalyst, 1～10% inhibitor, 1～15% tackifier, 1～10% thermal conductive filler and 1～10% flame retardant filler . The method of the present invention adopts a specific encapsulation material and can form a package body of a specific shape by vacuum dispensing without collapse and the like, and endows good thermal conductivity and flame retardancy under the premise of ensuring excellent mechanical properties.

Description

A preparation method of a COB surface light source with a large luminous angle

technical field

The invention relates to the field of preparation of LED light sources, in particular to a preparation method of a COB surface light source with a large luminous angle.

Background technique

Semiconductor light-emitting diode (LED) is a semiconductor that can convert electrical energy into visible light. It has changed the principle of incandescent lamp tungsten light emission and energy-saving lamp three-based toner light emission, and the use of electric field light emission, the advantages of LED are very obvious, with long life , high light efficiency, no radiation and low power consumption. LED has begun to be widely used in outdoor lighting, landscape lighting, agricultural lighting and other fields.

As the fourth-generation lighting source, LED has become a new type of green light source due to its incomparable advantages of energy saving, environmental protection, long life, and small size. It is considered to be an ideal substitute for traditional light sources and has become the most promising field in the 21st century. one.

At present, the packaging of LEDs generally adopts planar packaging and mold top packaging. Planar packaging mainly includes patch and integration. The planar packaging method is easy to operate and has a high popularity rate, but it is not as good as the silicone lens packaging method in terms of effective luminous efficiency and luminous flux; and the light-emitting angle of the general SMD LED series is between 110 and 120 degrees, which will form a certain angle on the side and the back. Dark areas will affect the overall lighting effect and environmental aesthetics to a certain extent. Mold-top packaging uses silica gel to fill the hemispherical mold, and then heats and solidifies it to form a hemispherical lens. It's hard to bear.

The Chinese invention patent application with the application publication number CN 103183963A discloses a silicone resin encapsulant for LEDs, comprising: 10 to 90 parts by weight of silicone resin A, each molecule containing at least alkenyl, phenyl and Hydroxyl; 10-90 parts by weight of silicone resin B, which is the product obtained by further condensation reaction of silicone resin A under the catalysis of alkali or its aqueous solution, and each molecule contains at least alkene and phenyl directly connected with silicon; 5-50 Parts by weight of polysiloxane C, each molecule contains at least hydrogen and phenyl groups directly connected to silicon; 0.01-0.5 parts by weight of platinum catalyst D; 0.01-0.5 parts by weight of inhibitor E. Although the viscosity of the encapsulant can be flexibly adjusted, the cured structure has good uniformity, small stress, and excellent mechanical properties, but it is difficult to form a package with a specific shape in the dispensing process, and its mechanical properties need to be further improved.

The Chinese invention patent application with the application publication number CN 101935455A discloses a silicone material for LED packaging and its preparation method. Component A and component B are mixed at a mass ratio of 0.3:1 to 1:30, and then added to component D Components, E component and C component, prepared by mixing uniformly; the A component is vinyl polysiloxane, the B component is hydrogen-containing polysiloxane, and the C component Divided into a mixture of platinum complexes and inhibitors, the amount of component C used according to the amount of platinum complexes is that the mass of platinum metal element is 1-60ppm, and the molar ratio of inhibitors to platinum atoms is 2-150:1. The D component is vinyl MQ resin of (Me ₃ SiO) _e (MeViSiO) _f SiO ₂ , and the E component is ethyl orthosilicate, vinyl trimethoxysilane, n-butyl borate, boric acid One or more of isopropyl ester, titanium isooctanoate, n-butyl titanate, etc. The strength and hardness of the silicone material for LED packaging can be improved by adding D component (for increasing the mechanical strength and hardness of the packaging material) and E component (for increasing the bonding force between the packaging material and the LED package bracket). However, in the dispensing process, it is difficult to form a package with a specific shape, and it is prone to collapse and the like.

Contents of the invention

The invention provides a method for preparing a COB surface light source with a large luminous angle, using a specific silicone resin packaging material for LEDs, and vacuum dispensing to form a package with a specific shape without collapse.

A COB (Chip On Board, Chip On Board) surface light source with a large luminous angle adopts a package with a spherical cross section, which can increase the luminous angle and improve the uniformity of the emitted light.

A COB surface light source with a large luminous angle, comprising a substrate, an LED chip arranged on the substrate, and a package body for packaging the LED chip on the substrate, the package body is in the form of a cross-sectional sphere, and the cross-sectional sphere The cross-section is in close contact with the substrate and fixed with the substrate.

In the present invention, the packaging body with a cross-section spherical body is adopted, so that the light emitted by the LED chip has a relatively large luminous angle after being emitted from the packaging body, and the uniformity of the emitted light is also good.

In order to improve the adhesion between the package and the substrate and improve the stability of use, as a preference, the cross-sectional radius of the cross-sectional sphere is 0.5 to 1 times the radius of the sphere, and the cross-sectional radius is relatively large, that is, the cross-sectional sphere and the cross-sectional sphere The above-mentioned base plate is close to and fixed with a larger surface, which increases the supporting and stable surface. Further preferably, the sectional radius of the cross-sectional sphere is 0.8 to 1 times the radius of the sphere, so as to ensure a relatively large light-emitting angle and improve the uniformity of outgoing light.

Further preferably, the volume of the cross-sectional sphere is less than or equal to the volume of the truncated part of the cross-sectional sphere, that is, the cross-section of the cross-sectional sphere is the largest surface. While ensuring sealing and ease of use, this structure can be dispensing Process realization, easy to implement.

The substrate can be a transparent or opaque material, preferably, the substrate is a glass substrate, a ceramic substrate or a plastic substrate, all of which can well meet the requirements of use. Further preferably, the substrate is a ceramic substrate, which has better thermal conductivity and temperature resistance.

The substrate is provided with a solderable electrode, one end of the electrode is connected to the LED chip, and the other end is used to connect to an external circuit. The electrode material is gold, silver, nickel, aluminum, tin or alloys thereof.

There are a plurality of LED chips, and the plurality of LED chips form an LED chip array, which can increase the luminous intensity of the COB surface light source with a large luminous angle and improve the uniformity of illumination.

Each LED chip in the LED chip array is connected in series or/and in parallel. Generally, in the LED chip array, both series and parallel are used, that is, each branch has a certain number of LED chips in series, and then these branch The circuits are connected in parallel to form an LED chip array. Between the branches connected in parallel, if a certain branch does not work, it will not affect other branches. If a certain LED chip in a certain branch does not work, it will cause the branch to not work normally, but it will not It affects other branches, thus ensuring the normal use of the COB surface light source with a large luminous angle.

The packaging body is made of yellow fluorescent powder and silicone resin packaging material for LEDs, and the mass ratio of the yellow fluorescent powder to the silicone resin packaging material for LEDs is 0.1-1:100.

The yellow phosphor is cerium-doped yttrium aluminum garnet yellow phosphor, that is, YAG:Ce ³⁺ yellow phosphor, which can be effectively excited by 405nm-510nm blue light, emits efficient visible light, and has stable physical and chemical properties. Cerium-doped yttrium-aluminum-garnet yellow phosphor can be prepared using existing technologies. For details, please refer to the literature "Wet chemical preparation and characterization of cerium-doped yttrium-aluminum garnet phosphor" (Guo Rui, Xiamen University, published on May 01, 2008, master's thesis), high-temperature solid-state reaction method, sol-gel method, spray pyrolysis method, co-precipitation method, step-by-step precipitation method, uniform precipitation method, combustion synthesis method, etc. can be used. Preferably, the co-precipitation method is used to prepare the cerium-doped yttrium aluminum garnet yellow phosphor (Y _2.94 Al ₅ O ₁₂ :0.06Ce ^{3 +} ), that is, the Ce ³⁺ concentration is 0.06, which has good luminous intensity.

A method for preparing a COB surface light source with a large luminous angle, comprising the following steps:

Electrically connect the LED chip to the substrate, preheat the substrate, mix the silicone resin encapsulation material for the LED with the yellow phosphor powder, then place the mixed material on the preheated substrate by vacuum dispensing, and heat and solidify to form COB surface light source with large beam angle.

The invention also provides an organic silicon resin encapsulation compound for LEDs, which endows the organic silicon resin encapsulation material for LEDs with good thermal conductivity and good flame retardancy under the premise of ensuring excellent mechanical properties.

A silicone resin encapsulant for LEDs, made of the following components in mass percentage:

Preferably, the silicone resin encapsulant for LED is made of the following components in mass percentage:

Further preferably, the silicone resin encapsulant for LED is made of the following components in mass percentage:

Vinyl silicone oil, that is, polymethyl vinyl siloxane, as a base glue, is composed of Si-O-Si main chain, mainly including: terminal vinyl type silicone oil, side chain vinyl type silicone oil and terminal/side chain vinyl Type silicone oil has good physical and mechanical properties, mainly reflected in: good weather resistance, UV aging resistance and moisture resistance, better transparency than epoxy resin under visible light, slowing down the light attenuation of LEDs, Increased light transmittance, improved luminous intensity and efficiency.

Hydrogen-containing silicone oil, that is, hydrogen-based polymethylsiloxane, as a crosslinking agent, can improve the mechanical properties of silicone resin encapsulants for LEDs.

Platinum catalysts can accelerate the addition reaction to form silicone rubber. Preferably, the platinum catalyst is chloroplatinic acid-divinyltetramethyldisiloxane or chloroplatinic acid-isopropanol.

Inhibitor, to ensure the storage period and pot life of the addition-type liquid silicone rubber, and the inhibitor that can delay the addition reaction of hydrosilation, has met the needs of production and application. Inhibitors can use existing technologies, including: 1. Organic compounds containing N, P, and S; 2. Heavy metal particle compounds containing Sn, Pb, Hg, Bi, As, etc.; 3. Alkyne and polyvinyl compounds compounds etc. Preferably, alkynyl cyclohexanol can be used, specifically ethynyl cyclohexanol can be used.

The tackifier can increase the cohesiveness between the various components, so that the silicone resin encapsulation compound for LEDs has good mechanical properties. As preferably, the tackifier is a compound tackifier, which is a combination of fumed white carbon black, γ-(2,3-glycidoxy)propyltrimethoxysilane and methyltrimethoxysilane Among them, the fumed silica mainly plays the role of thickening, thixotropy and fluidity control. After uniform dispersion, the active silicon hydroxyl groups on the surface of the silica are easy to form hydrogen bonds with the polymer, resulting in a structural effect and forming The network structure increases the viscosity of the system. Fumed silica can be used as a reinforcing agent, which can not only improve the tear strength and wear resistance of the product, but also significantly improve the aging resistance and electrical insulation properties of the rubber compound. Fumed white carbon black can also play a certain role in heat conduction in the silicone resin packaging material for LEDs. γ-(2,3-Glycidoxypropoxy)propyltrimethoxysilane and methyltrimethoxysilane are compounded together, leaving a large amount of silicon hydroxyl groups, which can make each component better when the silicone rubber is cured At the same time, the compound tackifier itself is also a multi-branched Si-O-Si structure, which can cooperate with the flame-retardant filler to hinder the combustion of the composite material. Preferably, the mass ratio of fumed silica, γ-(2,3-glycidoxy)propyltrimethoxysilane and methyltrimethoxysilane is 1:1:0.6˜1. Therefore, the use of fumed silica, γ-(2,3-glycidoxy)propyltrimethoxysilane and methyltrimethoxysilane as tackifiers can not only improve the mechanical properties of the material, but also Synergizes with thermally conductive fillers and flame retardant fillers to improve thermal conductivity and flame retardancy.

The thermally conductive filler can improve the thermal conductivity of the silicone resin encapsulant for LEDs. The thermally conductive filler is one or more of silicon oxide, aluminum oxide (namely aluminum oxide), magnesium oxide, zinc oxide, aluminum oxide, boron nitride, silicon carbide, etc.

Flame retardant fillers can improve the flame retardant properties of silicone resin packaging materials for LEDs. Preferably, the flame retardant filler is one of aluminum hydroxide, magnesium hydroxide, zinc borate, etc., which can not only be flame retardant, but also produce smoke, no dripping, and no poisonous gas.

In the present invention, through the compounding of various components, the silicone resin encapsulating compound for LEDs of the present invention is endowed with good thermal conductivity and flame retardancy, and at the same time, the organosilicon resin encapsulating compound for LEDs of the present invention can also have excellent mechanical properties .

The preparation method of described LED encapsulation compound with silicone resin, comprises the following steps:

Add thermal conductive filler, flame retardant filler and tackifier to vinyl silicone oil, mix evenly, then add hydrogen-containing silicone oil and inhibitor, and finally add platinum catalyst, mix evenly, vacuumize and defoam to get silicone resin for LED Packaging material.

The prepared silicone resin encapsulation material for LED needs to be used immediately.

Compared with prior art, the present invention has following advantage:

The COB surface light source with a large luminous angle adopts a package with a spherical cross section, so that the light emitted by the LED chip has a larger luminous angle after passing through the package, and the uniformity of the emitted light is also better. The COB surface light source with a large luminous angle has a simple structure, low production cost, easy market promotion and application, and has broad application prospects.

The preparation method of the COB surface light source with a large luminous angle of the present invention adopts a specific silicone resin encapsulation material for LEDs, and can form an encapsulation body of a specific shape through vacuum dispensing without collapse. The silicone resin encapsulant for LED, on the premise of ensuring excellent mechanical properties, endows the silicone resin encapsulant for LED with good thermal conductivity and good flame retardancy.

Description of drawings

Figure 1 is a schematic diagram of the structure of a COB surface light source (single) with a large luminous angle;

Figure 2 is a schematic diagram of the structure of a COB surface light source (LED chip array) with a large light-emitting angle.

detailed description

As shown in Figure 1 and Figure 2, it is a COB surface light source (single) and (LED chip array) with a large light emitting angle, including a substrate 1, an LED chip arranged on the substrate 1, and a package for LED chips on the substrate 1 The package body 2 is in the shape of a sphere with a cross section, and the section of the sphere 2 is in close contact with the substrate 1 and fixed with the substrate 1 . The cross-section radius of the cross-section sphere 2 can be 0.5 to 1 times the radius of the sphere, and further can be 0.8 to 1 times the radius of the sphere. In Figures 1 and 2, the cross-section sphere 2 is a hemisphere, that is, the cross-section radius of the cross-section sphere 2 is a sphere 1 times the radius. The volume of the sectional sphere 2 is equal to the volume of the truncated portion of the sectional sphere 2 . The substrate 1 is a glass substrate, a ceramic substrate or a plastic substrate. In Fig. 1, a ceramic substrate is specifically selected. Solderable electrodes are provided on the substrate 1, one end of the electrode is connected to the LED chip, and the other end is used to connect to an external circuit. In Fig. 2, there are multiple LED chips, that is, there are also multiple package bodies 2, and the multiple LED chips form an LED chip array, and each LED chip in the LED chip array is connected in series or/and in parallel.

Example 1

A method for preparing a COB surface light source with a large luminous angle, comprising the following steps:

Electrically connect the LED chip (blue LED chip, Aixtron, Germany, GaN-based blue LED chip on Si substrate, 1w) to the electrodes on the substrate 1, preheat the substrate 1, and add γ-(2, 3-glycidoxy)propyltrimethoxysilane, methyltrimethoxysilane, fumed white carbon black, aluminum oxide and aluminum hydroxide, stirred by a disperser, vacuumed for defoaming and standing for 3h Finally, add hydrogen-containing silicone oil and ethynyl cyclohexanol and mix evenly, and finally add chloroplatinic acid-divinyltetramethyldisiloxane and cerium-doped yttrium aluminum garnet yellow phosphor (Y _2.94 Al ₅ O ₁₂ : 0.06Ce ³⁺ ), stirred evenly and vacuum degassed, then put the mixed material on the preheated substrate 1 with a vacuum dispenser to form a package with a specific shape, and then cured at 100°C for 1h and 150°C Continuous heating and curing in 30min sequence to form a COB surface light source with a large luminous angle. The package body 2 has a radius of 0.9 cm. Others are the same as in Fig. 1, that is, the structural description in the specific embodiment. The mass ratio of the cerium-doped yttrium aluminum garnet yellow phosphor powder to the silicone resin encapsulating material for LED is 0.5:100.

For the silicone resin encapsulation material for LED, the raw materials with the following mass percentages are selected:

Vinyl silicone oil: 300mPa s, 0.7% ethylene mass percentage, industrial grade, Zhejiang Xin'an Chemical Group Co., Ltd.;

Hydrogen-containing silicone oil: 0.5% hydrogen by weight, industrial grade, Guangzhou Sihai Chemical Co., Ltd.;

Aluminum oxide: particle size 0.5μm, industrial grade;

Aluminum hydroxide: particle size 0.3μm, industrial grade;

Fumed silica: Shenyang Chemical Co., Ltd.

Example 2

The organic silicon resin encapsulation material for LED is selected from the following raw materials in mass percentage:

Others are the same as embodiment 1.

Example 3

The organic silicon resin encapsulation material for LED is selected from the following raw materials in mass percentage:

Others are the same as embodiment 1.

Example 4

The organic silicon resin encapsulation material for LED is selected from the following raw materials in mass percentage:

Others are the same as embodiment 1.

Example 5

For the silicone resin encapsulation material for LED, the raw materials with the following mass percentages are selected:

Others are the same as embodiment 1.

Comparative example 1

For the silicone resin encapsulation material for LED, the raw materials with the following mass percentages are selected:

Others are the same as embodiment 1.

Comparative example 2

For the silicone resin encapsulation material for LED, the raw materials with the following mass percentages are selected:

Others are the same as embodiment 1.

Tensile strength and elongation at break: measured by electronic universal testing machine according to GB/T 528-2009; shear strength: measured by electronic universal testing machine according to GB/T 13936-1992.

Combustion performance test: Determine the vertical combustion rating according to GB/T 10707-2008.

Thermal conductivity test: Measured according to GB/T 11205-1989, point the mixed material on the plate with a vacuum dispenser to form a sample of 150mm×150mm×3mm, add a stable temperature on the hot surface, and the heat will be transferred through the sample To the cold surface, measure the heat flow transferred, and then calculate the thermal conductivity based on the thickness of the sample and the heat transfer area.

λ=(Q·L)/[A·(Ta-Td)]

λ: thermal conductivity of the material, W m ^-1 K ^-1 ; Q: heat flow, W; A: cross-sectional area of the sample, m ² ; L: thickness of the sample, m; Ta: temperature of the hot surface of the sample, K; Td: temperature of the cold surface of the sample, K.

Table 1 shows the test results of the packages on the COB surface light sources with large light emitting angles in Examples 1-5. According to the emission curves of COB surface light sources with large emission angles in Examples 1 to 5, the average beam angles (50%) of the COB surface light sources with large emission angles in Examples 1 to 5 are 176.2 degrees, 175.6 degrees, and 175.8 degrees, respectively. , 175.5 degrees and 172.1 degrees, the light angle is larger.

Table 1

It can be seen from Table 1 that the packages on the COB surface light sources with large light emitting angles in Examples 1-5 have good thermal conductivity and flame retardancy, and most importantly, they can also ensure that the materials have excellent mechanical properties.

Compared with Example 5, the tackifiers used in Example 1 are different, and fumed white carbon black, γ-(2,3-glycidoxy) propyltrimethoxysilane and methyltrimethoxysilane are used. The mixture of silane as a tackifier can not only improve the mechanical properties of the material, but also cooperate with aluminum hydroxide and aluminum oxide to improve the flame retardancy and thermal conductivity of the material.

From Example 1 and Comparative Example 1, it can be seen that without adding the flame-retardant filler aluminum hydroxide, only adding the thermally conductive filler Al2O3, the addition of Al2O3 is more, although the thermal conductivity and mechanical properties have a certain decline, But the overall performance is relatively good. Al2O3 can cooperate with the ingredients in the tackifier to improve thermal conductivity, and the thermal conductivity is good. Its combustion rating is UL-94, which is HB. This is mainly based on vinyl silicone oil and Properties of silicone material structure containing hydrogen silicone oil addition.

From Example 1 and Comparative Example 2, it can be seen that without adding the thermally conductive filler aluminum oxide, only adding the flame retardant filler aluminum hydroxide, the aluminum hydroxide can synergistically improve the flame retardancy with the components in the tackifier, making it have V -0 combustion rating, but because there is no thermal conductivity filler aluminum oxide, its thermal conductivity is poor.

Claims (8)

1. A method for preparing a COB surface light source with a large luminous angle, comprising the following steps: Electrically connect the LED chip to the substrate, preheat the substrate, mix the silicone resin encapsulation material for the LED with the yellow phosphor powder, then place the mixed material on the preheated substrate by vacuum dispensing, and heat and solidify to form COB surface light source with large beam angle; The silicone resin encapsulant for LED is made of the following components in mass percentage: The tackifier is a mixture of fumed white carbon black, γ-(2,3-glycidoxy)propyltrimethoxysilane and methyltrimethoxysilane. 2. the preparation method of the COB surface light source of large luminous angle according to claim 1, is characterized in that, the preparation of described LED silicone resin encapsulant comprises: Add thermal conductive filler, flame retardant filler and tackifier to vinyl silicone oil, mix evenly, then add hydrogen-containing silicone oil and inhibitor, and finally add platinum catalyst, mix evenly, vacuumize and defoam to get silicone resin for LED Packaging material. 3. The method for preparing a COB surface light source with a large luminous angle according to claim 1, characterized in that the mass ratio of the yellow phosphor to the silicone resin encapsulant for LED is 0.1-1:100. 4. the preparation method of the COB surface light source of large luminous angle according to claim 1 is characterized in that, described fumed silica, gamma-(2,3-glycidoxy) propyltrimethoxy The mass ratio of methyl silane to methyl trimethoxy silane is 1:1:0.6~1. 5. The method for preparing a COB surface light source with a large luminous angle according to claim 1, wherein the COB surface light source with a large luminous angle comprises a substrate, an LED chip arranged on the substrate, and an LED chip for A packaging body in which the LED chip is packaged on the substrate, the packaging body is in the form of a sphere with a cross-section, and the cross-section of the sphere is in close contact with the substrate and fixed with the substrate. 6 . The method for preparing a COB surface light source with a large luminous angle according to claim 5 , wherein the cross-sectional radius of the cross-sectional sphere is 0.5 to 1 times the radius of the sphere. 7 . 7 . The method for preparing a COB surface light source with a large lighting angle according to claim 5 , wherein the volume of the cross-sectional sphere is smaller than or equal to the volume of the truncated portion of the cross-sectional sphere. 8 . 8. The method for preparing a COB surface light source with a large light emitting angle according to claim 1, wherein the LED chips are multiple, and a plurality of LED chips form an LED chip array, and each LED in the LED chip array The chips are connected in series or/and in parallel.