CN104809272A - LED (Light Emitting Diode) chip light extraction rate prediction method - Google Patents

Abstract

The invention discloses a method for predicting the light extraction rate of an LED chip, comprising the following steps: (1) constructing a packaging substrate model by using the modeling function of computer 3D modeling software; (2) constructing a packaging resin model by using computer 3D modeling software (3) Use TracePro software to import the LED package model and chip model to form a complete LED package model; (4) Build the target surface: use the built-in modeling function of TracePro software to make six rectangular target surfaces; (5) use TracePro software The ABg model function in the BSDF function in the set optical parameters; (6) use the sweeping system of TracePro software to collect and record data; (7) predict the light extraction rate. On the premise of ensuring conformity with actual conditions, the invention shortens the modeling process and calculation time to improve efficiency and realize zero-cost optimization.

Description

A Prediction Method of Light Extraction Efficiency of LED Chip

technical field

The invention relates to the design field of LED chips, in particular to a method for predicting the light extraction rate of LED chips.

Background technique

As an emerging green solid-state lighting source, light-emitting diode (LED) has the advantages of high brightness, low power consumption, long life, fast start-up, etc., and has great application value. Compared with traditional lighting sources such as incandescent lamps, energy-saving lamps and fluorescent lamps, LEDs have overwhelming advantages in luminous efficiency and service life. Furthermore, at present, there is still a lot of room for improvement in the luminous efficiency of LEDs. Improving the luminous efficiency of LEDs can help reduce the production cost per unit of luminous output, which is of great significance for the promotion of LEDs in a wider range. To this end, relevant researchers have invented technologies such as patterned sapphire substrates, surface roughening, flip chips, and photonic crystals. Among them, the patterned sapphire substrate technology uses micro-nano electromechanical technology to produce micron-scale or nano-scale patterns with a certain array pattern on the surface of the sapphire substrate, and controls the scattering of light with the help of micro-patterns to improve the light extraction rate; surface roughening technology Then, by roughening the surface of the LED chip and changing the surface morphology to change the scattering of light on the surface to obtain a greater surface light overflow rate; The package substrate is connected, so that the transparent sapphire substrate surface on the back of the chip becomes the main light-emitting surface, thereby increasing the luminous flux; photonic crystal technology uses the diffraction effect of photonic crystals on light to improve the "light" caused by total reflection that is common in LED chips. Confinement" problem, in order to improve the light extraction rate. When the above technologies are used alone on the LED chip, the light extraction rate of the LED chip can be improved to varying degrees, thereby improving the external quantum efficiency.

There are many techniques for improving the light extraction rate mentioned above, and in actual situations, multiple technologies are often applied together in order to obtain a higher effect of improving the light extraction rate. In this case, the interaction between various technologies is very complicated, and the lack of systematic scientific theory and rich experimental experience guidance makes optimization difficult. Therefore, it is particularly important to accurately evaluate the light extraction rate of LEDs and systematically optimize the technical parameters to obtain a higher lifting effect. However, at this stage, the light extraction rate of LEDs can only be reflected through actual chip testing, and the steps are cumbersome and the progress is slow. Not only that, but in the current optimization process, a large number of experiments and comparative verification are required to obtain ideal optimization parameters, which greatly reduces efficiency and increases design costs.

Therefore, there is an urgent need for a systematic, accurate, convenient and efficient evaluation mechanism for accurately predicting the light extraction rate of LEDs. In addition to avoiding tedious and high-cost actual product preparation, this method also needs to be guided by scientific and rigorous physical theories and mathematical models to ensure the accuracy and reliability of the method. At the same time, due to the complexity and diversity of LED product structures, this prediction method needs to be adapted to chip structures such as front-mount, flip-chip (Flip Chip), and vertical, as well as various packaging methods including SMD type and power type.

Contents of the invention

In order to overcome the above-mentioned shortcomings and deficiencies of the prior art, the object of the present invention is to provide a method for predicting the light extraction rate of LED chips, which shortens the modeling process and calculation time and improves the efficiency under the premise of ensuring compliance with the actual situation. .

The object of the present invention is achieved through the following technical solutions:

A method for predicting the light extraction rate of an LED chip, comprising the following steps:

(1) Construct the packaging substrate model: use the modeling function of the computer 3D modeling software to build the packaging substrate, and use the Boolean operation difference function of the computer 3D modeling software to cut out the groove in the center of the packaging substrate to form the LED chip The model provides the location;

(2) Construct the encapsulation resin model: use computer 3D modeling software to establish the encapsulation resin that fills the groove obtained in step (1), and use the Boolean operation difference function of the software to cut out vacancies for the LED chip model in the encapsulation resin ;

(3) Import the LED package model and chip model: use the insert part function that comes with the TracePro software to import the LED chip model and the package substrate built in step (1) and the package substrate and package that have been built in step (2). Resin model to form a complete LED package model;

(4)) Build the target surface: use the modeling function that comes with the TracePro software to make six rectangular target surfaces, and the six target surfaces are respectively placed on the upper, lower, front, rear, left, and right sides of the packaging model to surround The entire package model;

(5) Set optical parameters: use the ABg model function in the BSDF function in TracePro to set the Ag reflection cup parameters for the groove surface of the packaging substrate; use the material properties, surface properties, and volume scattering properties in TracePro to set the parameters for the packaging resin and LED chips Set light performance parameters;

(6) Collecting and recording data: using the sweeping system of TracePro software, ray tracing is carried out on the LED package model, and the luminous flux data on the six target surfaces are respectively obtained, and the total luminous flux is obtained by summing;

(7) Prediction of light extraction rate: Calculate the ratio of the luminous parameters set by the LED chip model to the total luminous flux to obtain the light extraction rate.

The light performance parameters in step (5) include refractive index, temperature setting, absorption rate, extinction coefficient, wavelength of outgoing light, parameters of the ABg model in the surface BSDF function, and parameters of the volume scattering model.

Step (1) Use the modeling function of computer 3D modeling software to construct the packaging substrate, specifically:

Use the modeling function of computer 3D modeling software to construct cylindrical or square packaging substrates.

The structure of the LED package model in step (3) is a SMD LED or an LED lamp bead.

The LED chip model described in step (3) is a front-mount, flip-chip or vertical chip structure.

The groove in step (1) is a conical groove or a cylindrical groove.

The computer 3D modeling software is SolidWorks software.

With the help of the physical theory and mathematical model of optical propagation, the present invention uses optical theories such as reflection, refraction, light absorption principles, etc. to simulate the propagation path of light in the chip and packaging structure, and calculates the average behavior of a large number of light through the computer, and finally calculates Enhancement effect of light extraction rate.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

(1) The present invention models the full structure model of the LED package, realizes the simulation at the level of the entire LED chip and package, and predicts the light extraction rate of the product based on the final total luminous flux. The result is closer to the actual situation and has a reference value.

(2) The model of the present invention is rationally simplified, and the modeling process and calculation time are shortened under the premise of ensuring conformity with the actual situation, and the efficiency is improved.

(3) The present invention strictly conforms to the physical theory of light propagation and has an accurate mathematical modeling model, so it is scientific and rigorous, and can well reflect the actual light propagation situation.

(4) The present invention supports micro-adjustment of parameters, can systematically study the influence of various parameters of various technologies on the light output efficiency of LEDs, and realizes zero-cost optimization without the need for finished products to detect performance.

(5) The present invention uses a statistical approximation model to realize the simulation of multiple techniques for improving the light extraction rate, and can perform joint simulations of multiple techniques to systematically optimize various technical parameters to obtain the best optimization results.

(6) The present invention can simulate the light extraction efficiency of LEDs made of various materials and LEDs under various packaging standards as required, and provide new ideas for finding better LED epitaxial structures, substrate materials and packaging structures.

Description of drawings

FIG. 1 is a front view of an LED package model according to Embodiment 1 of the present invention.

Fig. 2 is a top view of the LED packaging model of Embodiment 1 of the present invention.

Fig. 3 is a left side view of the LED package model of Embodiment 1 of the present invention.

FIG. 4 is a flowchart of a method for predicting the light extraction rate of an LED chip according to an embodiment of the present invention.

Fig. 5 is a front view of an LED package model according to Embodiment 2 of the present invention.

Fig. 6 is a top view of an LED package model according to Embodiment 2 of the present invention.

Fig. 7 is a left side view of an LED package model according to Embodiment 2 of the present invention.

Detailed ways

The present invention will be described in further detail below in conjunction with the examples, but the embodiments of the present invention are not limited thereto.

Example 1

1 to 3 are three views of the 5050 SMD LED package model of this embodiment, which is composed of an externally introduced LED chip 11 , a package substrate 12 and a package resin 13 .

As shown in Figure 4, the method for predicting the light extraction rate of the LED chip of this embodiment includes the following steps:

(1) Constructing the package substrate model: use the modeling function of SolidWorks software to construct a cuboid substrate with a size of 750mm×750mm×150mm, and use the Boolean operation difference function of the software to cut out a height of 120mm in the center, up and down The frustum-shaped grooves with circular radiuses of 330mm and 225mm respectively.

(2) Construct encapsulation resin model: adopt SolidWorks software, according to the groove shape that establishes in (1), establish the encapsulation resin that fills the conical groove that step (1) obtains, utilize the Boolean operation subtraction function of SolidWorks software in resin Cut out a space of 120mm×120mm×104.275mm for the LED chip;

(3) Import the LED package model and chip model: use the function of inserting parts that comes with TracePro software, import the LED chip from the outside, and the package substrate and package resin model that have been built in steps (1) and (2) respectively, and the composition is complete the LED model;

In this embodiment, a hexagonal pyramid hemisphere mixed-pattern patterned sapphire substrate chip and a non-patterned sapphire substrate chip are respectively imported from the outside.

(4) Build the target surface: adopt the modeling function that TracePro software carries to make six rectangular target surfaces, and the six target surfaces are respectively placed on the upper, lower, front, rear, left and right sides of the packaging model;

In this embodiment, the size of the target surface is 1000mm×1000mm×2mm, and the center positions in the Cartesian coordinate system are (0,0,501), (0,0,-501), (0,501,0), (0,-501, 0), (501,0,0), and (-501,0,0).

(5) Set optical parameters: Use the ABg model function in the BSDF function in TracePro to set the Ag reflector cup parameters for the groove surface in the package substrate model; use the material properties, surface properties, and volume scattering properties in TracePro to set the parameters for the packaging resin and LED The chip sets the optical performance parameters;

In this embodiment, the material of the chip is imported from the outside world, the refractive index of the packaging resin is 1.41, the parameters of the Ag reflector cup are the absorption rate of 5%, and the specular reflectance of 80%. The software comes with function calculation. Set surface0, surface7, and surface8 on the substrate model.

(6) Collecting and recording data: using the light sweeping system of TracePro software, ray tracing is carried out on the package model, and the luminous flux data on the six target surfaces are respectively obtained, and the total luminous flux is obtained by summing;

In this embodiment, the light-sweeping system of TracePro software is used to perform ray tracing on the LED package model, and the luminous flux data of each surface is obtained from the radiance analysis diagram obtained by using the TracePro software, wherein the total luminous flux of the LED package model is +z target surface The sum of surface1, -z surface0, +y surface2, -y surface4, +x surface5 and -z surface3.

(7) Analyze the light extraction rate of the LED packaging model: according to the ratio of the luminous parameters set by the LED chip model and the total luminous flux, the light extraction rate is obtained;

The geometric dimensions in this embodiment all adopt the equivalent magnification method, and the dimensions are enlarged to 150 times of the actual value. Through this method, the computational complexity can be effectively reduced to improve efficiency.

In this embodiment, the chip is imported and the light source is set as a Lambertian light source, which contains 6000 rays and a total luminous flux of 10000 a.u.a.u. In step (6), the conical patterned sapphire substrate chip and the non-patterned sapphire substrate chip are scanned and compared, and the total sum of the luminous fluxes of each target surface is calculated to be 7795a.u.a.u. and 4606a.u.a.u. respectively. The light efficiencies calculated in step (7) are 77.95% and 46.06%, respectively. After using patterned sapphire substrate technology, the light extraction efficiency is increased by 69.23%. In the actual device, the light extraction rate of the patterned substrate LED can be increased by more than 50% compared with the traditional substrate LED, and the simulation results are consistent with the actual situation.

Example 2

5 to 7 are three views of the LED bead packaging model of this embodiment, which is composed of an LED chip 21 introduced from the outside, a packaging substrate 22 and a packaging resin 23 .

The prediction method of the LED chip light extraction rate of the present embodiment comprises the following steps:

(1) Construct the package substrate model: Use the modeling function of SolidWorks software to construct a cylindrical substrate with a size of 500mm in radius and 200mm in height, and use the Boolean operation difference function of the software to achieve a central cut of 120mm in height and 405mm in radius cylindrical grooves.

(2) Construct the packaging resin model: use SolidWorks software, according to the groove shape of the LED packaging structure established in (1), establish a cylindrical packaging resin filled with a cylindrical groove and a hemispherical head with a diameter of 810mm on the top, the software The Boolean operation difference set function cuts out a vacancy of 120mm×120mm×104.275mm for the LED chip in the resin;

(3) Import the LED packaging model and chip model: use the insert part function of the TracePro software to import from the outside the LED chip that is compatible with the packaging resin and the package substrate and packaging resin model that has been built with luminescent properties;

In this embodiment, a patterned sapphire substrate chip with a triangular-pyramid-hexagonal-pyramid mixed pattern is imported from the outside, and the center-to-center spacing of the patterns is changed to three groups of 4 μm, 6 μm, and 8 μm while keeping other parameters unchanged.

(4) Build the target surface: use the modeling function that comes with TracePro software to make six rectangular target surfaces, and the six target surfaces are respectively placed on the package model’s top +z, bottom -z, front +y, and rear -y , right+x and left-x;

In this embodiment, the size of the target surface is 1000mm×1000mm×2mm, and the center positions in the Cartesian coordinate system are (0,0,501), (0,0,-501), (0,501,0), (0,-501, 0), (501,0,0), and (-501,0,0).

(5) Set optical parameters: Use the ABg model function in the BSDF function in TracePro to set the Ag reflector cup parameters for the groove surface in the package substrate model; use the material properties, surface properties, and volume scattering properties in TracePro to set the parameters for the packaging resin and LED The chip sets the optical performance parameters;

In this embodiment, the material of the chip is imported from the outside world, the refractive index of the packaging resin is 1.41, the parameters of the Ag reflector cup are the absorption rate of 5%, and the specular reflectance of 80%. The software comes with function calculation. Set surface0, surface5, and surface6 on the substrate model.

(6) Collecting and recording data: using the light sweeping system of TracePro software, ray tracing is carried out on the package model, and the luminous flux data on the six target surfaces are respectively obtained, and the total luminous flux is obtained by summing;

In this embodiment, the light-sweeping system of TracePro software is used to perform ray tracing on the LED package model, and the luminous flux data of each surface is obtained from the radiance analysis diagram obtained by using the TracePro software, wherein the total luminous flux of the LED package model is +z target surface The sum of surface1, -z surface0, +y surface2, -y surface4, +x surface5 and -z surface3.

(7) Analyze the light extraction rate of the LED packaging model: according to the ratio of the luminous parameters set by the LED chip model and the total luminous flux, the light extraction rate is obtained;

The geometric dimensions in this embodiment all adopt the equivalent magnification method, and the dimensions are enlarged to 200 times of the actual value.

In this embodiment, the chip is imported and the light source is set as a Lambertian light source, which contains 6000 rays and a total luminous flux of 10000 a.u.a.u. After the triangular-pyramid-hexagonal-pyramid mixed-pattern chip is scanned in step (6), calculate the total value of the luminous flux of each target surface. The luminous flux of the chip with the pattern center spacing of 4 μm, 6 μm, and 8 μm is 7895a.u.a.u., 7855a.u.a.u., and 7781a, respectively. u.a.u. The light efficiencies calculated in step (7) are 78.95%, 78.55% and 77.81%, respectively. This embodiment reflects the difference in light extraction rate of LEDs under different technical parameters. The highest light extraction rate is obtained when the center-to-center spacing of the substrate pattern is 4 μm, so the center-to-center spacing of 4 is selected as the optimized pattern parameter. By extending this embodiment, it can be used in the screening and optimization of more patterned substrate parameters.

The above-mentioned embodiment is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited by the embodiment, and any other changes, modifications, substitutions and combinations made without departing from the spirit and principle of the present invention , simplification, all should be equivalent replacement methods, and are all included in the protection scope of the present invention.

Claims (7)

1. A predictive method of LED chip light extraction rate, is characterized in that, comprises the following steps: (1) Construct the packaging substrate model: use the modeling function of the computer 3D modeling software to build the packaging substrate, and use the Boolean operation difference function of the computer 3D modeling software to cut out the groove in the center of the packaging substrate to form the LED chip The model provides the location; (2) Build a packaging resin model: use computer 3D modeling software to build a packaging resin that fills the groove obtained in step (1), and use the Boolean operation difference function of the software to cut out vacancies for the LED chip model in the packaging resin ; (3) Import the LED package model and chip model: use the insert part function that comes with the TracePro software to import the LED chip model and the package substrate built in step (1) and the package substrate and package that have been built in step (2). Resin model to form a complete LED package model; (4)) Build the target surface: use the modeling function that comes with the TracePro software to make six rectangular target surfaces, and the six target surfaces are respectively placed on the upper, lower, front, rear, left, and right sides of the packaging model to surround The entire package model; (5) Set optical parameters: use the ABg model function in the BSDF function in TracePro to set the Ag reflection cup parameters for the groove surface of the packaging substrate; use the material properties, surface properties, and volume scattering properties in TracePro to set the parameters for the packaging resin and LED chips Set light performance parameters; (6) Collecting and recording data: using the sweeping system of TracePro software, ray tracing is carried out on the LED package model, and the luminous flux data on the six target surfaces are respectively obtained, and the total luminous flux is obtained by summing; (7) Prediction of light extraction rate: Calculate the ratio of the luminous parameters set by the LED chip model to the total luminous flux to obtain the light extraction rate. 2. The prediction method of LED chip light extraction rate according to claim 1, it is characterized in that, the light performance parameter described in step (5) comprises refractive index, temperature setting, absorptivity, extinction coefficient, outgoing light wavelength, surface BSDF The parameters of the ABg model and the parameters of the volume scattering model in the function. 3. The prediction method of LED chip light extraction rate according to claim 1, is characterized in that, step (1) adopts the modeling function of computer 3D modeling software to construct packaging substrate, specifically: Use the modeling function of computer 3D modeling software to construct cylindrical or square packaging substrates. 4. The method for predicting the light extraction rate of an LED chip according to claim 1, wherein the structure of the LED package model in step (3) is a patch LED or an LED lamp bead. 5. The method for predicting the light extraction rate of LED chips according to claim 1, wherein the LED chip model in step (3) is a front-mounted, flip-chip or vertical chip structure. 6 . The method for predicting the light extraction rate of LED chips according to claim 1 , wherein the groove in step (1) is a conical groove or a cylindrical groove. 6 . 7. The prediction method of LED chip light extraction rate according to claim 1, is characterized in that, described computer 3D modeling software is SolidWorks software.