Packaging method of double-color-temperature COB light source

Abstract

The invention provides a packaging method for a double-color-temperature COB light source, and relates to the technical field of LED light source packaging. The packaging method of the double-color-temperature COB light source comprises the following steps of (1) substrate pretreatment, (2) chip die bonding, (3) lead bonding, (4) fluorescent powder layer preparation, (5) packaging glue filling and (6) curing treatment. The substrate is subjected to special pretreatment, so that the adhesive force between the substrate and the packaging material is improved, and the reliability of the light source is enhanced. Through high-precision chip die bonding and an optimized lead bonding process, the chip position precision and the electrical connection reliability are ensured, and the optical performance consistency of the light source is improved. Through precise fluorescent powder proportion regulation and control and an ink-jet printing coating technology, precise regulation and control of double color temperatures are achieved, and the lighting requirements of different scenes are met. Through precise fluorescent powder proportion regulation and control and an ink-jet printing coating technology, precise regulation and control of double color temperatures are achieved, and the lighting requirements of different scenes are met.

Description

Technical Field

[0001] The present invention relates to the technical field of LED light source packaging, and in particular to a packaging method for a dual-color temperature COB light source. Background Art

[0002] With the continuous development of lighting technology, dual-color temperature COB light sources have been widely used in commercial lighting, home lighting and other fields because they can provide lighting effects with different color temperatures in different scenarios and meet diverse lighting needs. However, existing dual-color temperature COB light source packaging methods have some problems. For example, the adhesion between the substrate and the packaging material during the packaging process is insufficient, resulting in reduced light source reliability; large deviations in the chip bonding position affect the consistency of optical performance; uneven phosphor coating makes it impossible to accurately control the dual color temperature; and the packaging glue has poor UV resistance and mechanical strength, shortening the service life of the light source. These problems limit the further development and application of dual-color temperature COB light sources. Therefore, a new packaging method is needed to solve the above problems. Summary of the Invention

[0003] In response to the shortcomings of the existing technology, the present invention provides a packaging method for a dual-color temperature COB light source, which solves the problems of insufficient adhesion between the substrate and the packaging material during the packaging process, resulting in reduced light source reliability, uneven phosphor coating, and inability to accurately control the dual color temperature.

[0004] To achieve the above objectives, the present invention is implemented through the following technical solutions: A packaging method for a dual-color temperature COB light source, comprising the following steps:

[0005] Step 1: Substrate pretreatment: cleaning and roughening the substrate surface, removing surface impurities using plasma cleaning technology, and performing microstructuring on the substrate surface using laser micromachining technology to increase the surface roughness of the substrate to a range of Ra0.5-2μm, in order to improve the adhesion between the subsequent packaging material and the substrate;

[0006] Step 2: Chip bonding: LED chips of different color temperatures are fixed to pre-designed areas on the substrate. Silver glue is used as the bonding material. The silver content of the silver glue is not less than 80%. A high-precision die bonding machine is used to ensure that the chip position deviation is less than ±20μm.

[0007] Step 3: Wire bonding, using a gold ball bonding process, using a gold wire with a diameter of 15-25μm. In terms of bonding parameters, the bonding pressure is controlled at 5-10g, the ultrasonic power is 10-20W, and the bonding time is 1-3ms to ensure a reliable electrical connection between the chip and the substrate;

[0008] Step 4: Preparation of phosphor layer: According to the dual color temperature requirements, mixed phosphor slurries with different phosphor ratios are prepared respectively. Yellow phosphor excited by blue light and green phosphor excited by red light are mixed in a specific ratio. The phosphor slurry is evenly coated on the chip surface by inkjet printing technology. The thickness of the phosphor layer is controlled at 50-150μm.

[0009] Step 5: Filling with encapsulant: Use high-transmittance, low-refractive-index silicone encapsulant in a vacuum environment with a vacuum degree of 10-100 Pa. During the filling process, control the flow rate of the encapsulant at 0.1-0.5 mL / s to ensure that the encapsulant evenly covers the chip and phosphor layer and avoids bubbles.

[0010] Step 6: Curing treatment: pre-curing at 80-100℃ for 30-60 minutes, and then fully curing at 120-150℃ for 1-2 hours to obtain a dual-color temperature COB light source.

[0011] Preferably, the substrate in step 1 is a ceramic substrate, the thermal conductivity of the ceramic substrate is greater than 20 W / (m·K), and the dielectric constant is between 5-10, so as to improve the heat dissipation performance and electrical insulation performance.

[0012] Preferably, in step 4, by adjusting the ratio of yellow phosphor excited by blue light and green phosphor excited by red light, precise control of dual color temperatures of 3000K-4000K and 5000K-6000K is achieved.

[0013] Preferably, in step five, nano-titanium dioxide particles with a mass fraction of 0.1%-0.5% are added to the organic silicon encapsulant to improve the UV resistance and mechanical strength of the encapsulant.

[0014] Preferably, after the curing treatment in step six, the optical performance test and screening of the packaged dual-color temperature COB light source is also included to eliminate products that do not meet the requirements of color temperature deviation of ±100K and color rendering index Ra lower than 85.

[0015] Preferably, the mixed phosphor slurry configured with different phosphor ratios further includes:

[0016] Measure the luminous efficiency of different batches of LED chips and record the corresponding data;

[0017] Analyze the relationship between the chip's luminous efficiency and the required phosphor ratio;

[0018] Adjusting the ratio of blue-light-excited yellow phosphor and red-light-excited green phosphor in the mixed phosphor based on the measured chip luminous efficiency;

[0019] If the phosphor ratio is P, the luminous efficiency of the chip is E, and when E < L, the phosphor ratio P is set to P1; when E > H, the phosphor ratio P is set to P2, where P represents the phosphor ratio, E represents the luminous efficiency of the LED chip, and L and H respectively represent the preset lower and upper luminous efficiency threshold values.

[0020] Preferably, the optimization of the substrate pretreatment step based on the specific parameters of the ceramic substrate further includes:

[0021] Determine the physical parameters of the ceramic substrate such as thermal conductivity and dielectric constant;

[0022] Compare the effects of different treatment methods on adhesion under specific parameter conditions;

[0023] Select the optimal surface roughness Ra and laser micromachining parameters based on the actual parameters;

[0024] If the roughness range is R, and when Ra is less than Rmin, adjust the plasma cleaning time and laser micromachining power; when Ra is greater than Rmax, reduce the treatment intensity, where Rmin and Rmax represent the set minimum and maximum roughness range limits.

[0025] Preferably, the adjustment of the wire bonding process based on the characteristics of the gold wire further includes:

[0026] Conduct tests using gold wires with specific tensile strength and diameter;

[0027] Examine the effects of different bonding pressures, ultrasonic powers, and bonding times on the bonding quality;

[0028] Select the most suitable bonding process based on the characteristics of the gold wire and the target requirements;

[0029] If the tensile strength of the gold wire is T and the diameter is D, and the goal is to maximize the electrical reliability, then when T * D ≥ Kmin, ensure that the process parameters are within the effective range, otherwise, appropriately reduce the bonding time and pressure.

[0030] The present invention provides a packaging method for a two-color temperature COB light source. It has the following beneficial effects:

[0031] 1. By performing special pretreatment on the substrate, the present invention improves the adhesion between the substrate and the packaging material, enhancing the reliability of the light source.

[0032] 2. Through high-precision chip die bonding and optimized wire bonding processes, the present invention ensures the chip position accuracy and electrical connection reliability, improving the optical performance consistency of the light source.

[0033] 3. The present invention realizes precise control of dual color temperature through precise phosphor ratio control and inkjet printing coating technology to meet the lighting needs of different scenes.

[0034] 4. The present invention improves the anti-ultraviolet performance and mechanical strength and prolongs the service life of the light source by adding the packaging glue of nano-titanium dioxide particles. DETAILED DESCRIPTION

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0036] Example 1:

[0037] An embodiment of the present invention provides a packaging method for a dual-color temperature COB light source, comprising:

[0038] Step 1: Substrate pretreatment: Select a ceramic substrate with a thermal conductivity greater than 20W / (m·K) and a dielectric constant of 5. First, use plasma cleaning technology to remove impurities on the substrate surface, and then use laser micromachining technology to perform microstructural processing on the substrate surface, controlling the substrate surface roughness within the range of Ra0.5μm. Based on the physical parameters of the ceramic substrate, such as thermal conductivity and dielectric constant, the effects of different treatment methods on adhesion under specific parameter conditions are compared, and the optimal surface roughness Ra and laser micromachining parameters are selected. If the roughness Ra is less than Rmin, adjust the plasma cleaning time and laser micromachining power; if Ra is greater than Rmax, reduce the treatment intensity to improve the adhesion between the subsequent packaging material and the substrate. By performing special pretreatment on the substrate, the adhesion between the substrate and the packaging material is improved, and the reliability of the light source is enhanced.

[0039] Step 2: Chip bonding: Fix LED chips of different color temperatures in pre-designed areas on the substrate. Use silver glue with a silver content of no less than 80% as the bonding material. Use a high-precision bonding machine to ensure that the chip position deviation is less than ±20μm.

[0040] Step 3. Wire bonding: The gold ball bonding process is adopted, and gold wires with a diameter of 15 μm are used. The bonding pressure is controlled at 5 g, the ultrasonic power is 10 W, and the bonding time is 1 ms. Gold wires with specific tensile strength and diameter are used for experiments to investigate the effects of different bonding pressures, ultrasonic powers, and bonding times on the bonding quality, and the most suitable bonding process is selected based on the characteristics of the gold wires and the target requirements of maximizing electrical reliability. If the tensile strength of the gold wire is T and the diameter is D, when T*D≥Kmin, ensure that the process parameters are within the effective range; otherwise, appropriately reduce the bonding time and pressure to ensure reliable electrical connection between the chip and the substrate. Through high-precision chip die bonding and optimized wire bonding processes, the chip position accuracy and electrical connection reliability are guaranteed, and the optical performance consistency of the light source is improved.

[0041] Step 4. Phosphor layer preparation: Measure the luminous efficiency of different batches of LED chips, record the corresponding data, and analyze the relationship between the chip luminous efficiency and the required phosphor ratio. According to the dual-color temperature requirements, adjust the ratio of blue-light-excited yellow phosphor and red-light-excited green phosphor in the mixed phosphor based on the measured chip luminous efficiency. If the phosphor ratio is P and the chip luminous efficiency is E, when E<L, set the phosphor ratio P = P1; when E>H, set the phosphor ratio P = P2 (where L and H respectively represent the preset lower and upper luminous efficiency thresholds). The mixed phosphor slurry is evenly coated on the chip surface through inkjet printing technology, and the thickness of the phosphor layer is controlled at 50 μm to achieve precise regulation of dual-color temperatures of 3000 K and 5000 K respectively. Through precise phosphor ratio regulation and inkjet printing coating technology, precise regulation of dual-color temperature is achieved, meeting the lighting requirements of different scenarios.

[0042] Step 5. Encapsulation glue filling: A high-transparency, low-refractive-index silicone encapsulation glue added with 0.1% by mass of nano-titanium dioxide particles is used for filling in a vacuum environment with a vacuum degree of 10 Pa. During the filling process, the flow rate of the encapsulation glue is controlled at 0.1 mL / s to ensure that the encapsulation glue evenly covers the chip and the phosphor layer, avoiding the generation of bubbles. By adding the nano-titanium dioxide particle-containing encapsulation glue, the ultraviolet resistance and mechanical strength are improved, and the service life of the light source is extended.

[0043] Step 6. Curing treatment: First, pre-cure at 80 °C for 30 minutes, and then completely cure at 120 °C for 1 hour to obtain a dual-color temperature COB light source.

[0044] Performance testing and screening: Conduct optical performance tests on the encapsulated dual-color temperature COB light sources, and reject products that do not meet the requirements of color temperature deviation of ±100 K and color rendering index Ra lower than 85.

[0045] Example 2: <000An embodiment of the present invention provides a packaging method for a dual-color temperature COB light source, including:

[0047] Step 1. Substrate pretreatment: Select a ceramic substrate with a thermal conductivity greater than 20W / (m·K) and a dielectric constant of 10. First, use plasma cleaning technology to remove impurities on the substrate surface, and then use laser micromachining technology to perform microstructural processing on the substrate surface, controlling the substrate surface roughness within the range of Ra0.5-2μm. Based on the physical parameters of the ceramic substrate, such as thermal conductivity and dielectric constant, compare the effects of different treatment methods on adhesion under specific parameter conditions, and select the optimal surface roughness Ra and laser micromachining parameters. If the roughness Ra is less than Rmin, adjust the plasma cleaning time and laser micromachining power; if Ra is greater than Rmax, reduce the treatment intensity to improve the adhesion of subsequent packaging materials to the substrate. By performing special pretreatment on the substrate, the adhesion between the substrate and the packaging material is improved, and the reliability of the light source is enhanced.

[0048] Step 2: Chip bonding: Fix LED chips of different color temperatures in pre-designed areas on the substrate. Use silver glue with a silver content of no less than 80% as the bonding material. Use a high-precision bonding machine to ensure that the chip position deviation is less than ±20μm.

[0049] Step 3, wire bonding: Use gold ball bonding process and gold wire with a diameter of 15-25μm. The bonding pressure is controlled at 10g, the ultrasonic power is 20W, and the bonding time is 3ms. Experiments are conducted using gold wire with specific tensile strength and diameter to examine the effects of different bonding pressures, ultrasonic power and bonding time on the bonding quality. The most suitable bonding process is selected based on the gold wire characteristics and the goal of maximizing electrical reliability. If the tensile strength of the gold wire is T and the diameter is D, when T*D≥Kmin, ensure that the process parameters are within the valid range. Otherwise, appropriately reduce the bonding time and pressure to ensure reliable electrical connection between the chip and the substrate. Through high-precision chip bonding and optimized wire bonding process, the chip position accuracy and electrical connection reliability are guaranteed, and the optical performance consistency of the light source is improved.

[0050] Step 4. Preparation of phosphor layer: Measure the luminous efficiency of LED chips in different batches, record the corresponding data, and analyze the relationship between the chip luminous efficiency and the required phosphor ratio. According to the dual-color temperature requirements, adjust the ratio of blue-light-excited yellow phosphor and red-light-excited green phosphor in the mixed phosphor based on the measured chip luminous efficiency. If the phosphor ratio is P and the chip luminous efficiency is E, when E < L, set the phosphor ratio P = P1; when E > H, set the phosphor ratio P = P2 (where L and H respectively represent the preset lower and upper luminous efficiency thresholds). Uniformly coat the mixed phosphor slurry on the chip surface through inkjet printing technology, control the thickness of the phosphor layer at 150 μm, and achieve precise regulation of dual-color temperatures of 4000K and 6000K. Through precise regulation of the phosphor ratio and inkjet printing coating technology, precise regulation of dual-color temperatures is achieved, meeting the lighting requirements of different scenarios.

[0051] Step 5. Filling of encapsulation glue: Use a high-transparency, low-refractive-index silicone encapsulation glue added with 0.5% by mass of nano-titanium dioxide particles for filling in a vacuum environment with a vacuum degree of 100 Pa. During the filling process, control the flow rate of the encapsulation glue at 0.5 mL / s to ensure that the encapsulation glue uniformly covers the chip and the phosphor layer and avoid generating bubbles. By adding the encapsulation glue with nano-titanium dioxide particles, the anti-ultraviolet performance and mechanical strength are improved, and the service life of the light source is extended.

[0052] Step 6. Curing treatment: First, perform pre-curing at 100 °C for 60 minutes, and then perform complete curing at 150 °C for 2 hours to obtain a dual-color temperature COB light source.

[0053] Performance testing and screening: Conduct optical performance testing on the encapsulated dual-color temperature COB light sources, and reject the products that do not meet the requirements of color temperature deviation of ±100K and color rendering index Ra lower than 85.

[0054] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A packaging method for a dual-color temperature COB light source, characterized by: The following steps are involved: Step 1: Substrate pretreatment: cleaning and roughening the substrate surface, removing surface impurities using plasma cleaning technology, and performing microstructuring on the substrate surface using laser micromachining technology to increase the surface roughness of the substrate to a range of Ra0.5-2μm, in order to improve the adhesion between the subsequent packaging material and the substrate; Step 2: Chip bonding: LED chips of different color temperatures are fixed to pre-designed areas on the substrate. Silver glue is used as the bonding material. The silver content of the silver glue is not less than 80%. A high-precision die bonding machine is used to ensure that the chip position deviation is less than ±20μm. Step 3: Wire bonding, using a gold ball bonding process, using a gold wire with a diameter of 15-25μm. In terms of bonding parameters, the bonding pressure is controlled at 5-10g, the ultrasonic power is 10-20W, and the bonding time is 1-3ms to ensure a reliable electrical connection between the chip and the substrate; Step 4: Preparation of phosphor layer: According to the dual color temperature requirements, mixed phosphor slurries with different phosphor ratios are prepared respectively. Yellow phosphor excited by blue light and green phosphor excited by red light are mixed in a specific ratio. The phosphor slurry is evenly coated on the chip surface by inkjet printing technology. The thickness of the phosphor layer is controlled at 50-150μm. Step 5: Filling with encapsulant: Use high-transmittance, low-refractive-index silicone encapsulant in a vacuum environment with a vacuum degree of 10-100 Pa. During the filling process, control the flow rate of the encapsulant at 0.1-0.5 mL / s to ensure that the encapsulant evenly covers the chip and phosphor layer and avoids bubbles. Step 6: Curing treatment: pre-curing at 80-100℃ for 30-60 minutes, and then fully curing at 120-150℃ for 1-2 hours to obtain a dual-color temperature COB light source.

2. The packaging method of a dual-color temperature COB light source according to claim 1, characterized in that: The substrate in step 1 is a ceramic substrate, and the thermal conductivity of the ceramic substrate is greater than 20 W / (m·K) and the dielectric constant is between 5 and 10, so as to improve the heat dissipation performance and electrical insulation performance.

3. The packaging method of a dual-color temperature COB light source according to claim 1, characterized in that: In step 4, by adjusting the ratio of yellow phosphor excited by blue light and green phosphor excited by red light, precise control of dual color temperatures of 3000K-4000K and 5000K-6000K is achieved.

4. The packaging method of a dual-color temperature COB light source according to claim 1, characterized in that: In step five, nano-titanium dioxide particles with a mass fraction of 0.1% to 0.5% are added to the organic silicon encapsulant to improve the anti-ultraviolet performance and mechanical strength of the encapsulant.

5. The packaging method of a dual-color temperature COB light source according to claim 1, characterized in that: After the curing treatment in step six, the optical performance testing and screening of the packaged dual-color temperature COB light source are also included, and products that do not meet the requirements of color temperature deviation of ±100K and color rendering index Ra below 85 are eliminated.

6. The packaging method of a dual-color temperature COB light source according to claim 1, characterized in that: The mixed phosphor slurry configured with different phosphor ratios further includes: Measure the luminous efficiency of different batches of LED chips and record the corresponding data; Analyze the relationship between the chip's luminous efficiency and the required phosphor ratio; Adjusting the ratio of blue-light-excited yellow phosphor and red-light-excited green phosphor in the mixed phosphor based on the measured chip luminous efficiency; If the phosphor ratio is P, the luminous efficiency of the chip is E, and when E < L, the phosphor ratio P is set to P1; when E > H, the phosphor ratio P is set to P2, where P represents the phosphor ratio, E represents the luminous efficiency of the LED chip, and L and H respectively represent the preset lower and upper luminous efficiency threshold values.

7. The packaging method of a dual-color temperature COB light source according to claim 2, characterized in that: The further optimization of the substrate pretreatment step based on the specific parameters of the ceramic substrate includes: Determine the physical parameters of the ceramic substrate, such as thermal conductivity and dielectric constant; Compare the effects of different treatment methods on adhesion under specific parameter conditions; Select the optimal surface roughness Ra and laser micromachining parameters based on the actual parameters; If the roughness range is R, and when Ra is less than Rmin, adjust the plasma cleaning time and laser micromachining power; when Ra is greater than Rmax, reduce the treatment intensity, where Rmin and Rmax represent the set minimum and maximum roughness range limits.

8. The packaging method of a dual-color temperature COB light source according to claim 1, characterized in that: The further adjustment of the wire bonding process based on the characteristics of the gold wire includes: Conduct tests using gold wires with specific tensile strength and diameter; Investigate the effects of different bonding pressures, ultrasonic powers, and bonding times on the bonding quality; Select the most suitable bonding process based on the characteristics of the gold wire and the target requirements; If the tensile strength of the gold wire is T and the diameter is D, and the goal is to maximize electrical reliability, then when T * D ≥ Kmin, ensure that the process parameters are within the effective range, otherwise, the bonding time and pressure should be appropriately reduced.