Si packaging substrate with light reflection structure and light absorption structure and preparation method thereof

Abstract

The invention discloses a Si packaging substrate with a light reflection structure and a light absorption structure and a preparation method thereof, the Si packaging substrate comprises a silicon-based substrate, the end face of the silicon-based substrate is provided with a plurality of grooves in an array mode, and the longitudinal section of each groove is in a V shape; the LED chip is positioned on the bottom surface of the groove through conductive solder, the light-emitting surface of the LED chip faces outwards, and the light conversion layer covers the light-emitting surface; the reflecting layer is arranged on the wedge-shaped side face of the groove and extends to the end face of the silicon-based substrate, and a passivation layer is arranged on the surface of the reflecting layer and / or between the surface of the reflecting layer and the end face of the silicon-based substrate; and the light absorption enclosing wall is arranged on the passivation layer on the outer side of the top of the groove and is of a continuous strip-shaped structure. According to the array micro light source, the problems of poor light utilization rate, poor light collimation and poor light crosstalk prevention performance when the existing array micro light source is used can be solved.

Description

Technical Field

[0001] The present invention relates to the technical field of lighting, and in particular to a Si packaging substrate with a light reflection structure and a light absorption structure and a preparation method thereof. Background Art

[0002] In existing adaptive driving beam (ADB) systems and micro-LED array light sources for 3D printing light sources, there are problems of insufficient collimation of each micro-light source and light crosstalk between micro-light sources. The preparation process of the packaging substrate is complex and costly, and during use, there is a large light loss, low light extraction efficiency and low light output efficiency. In addition, the divergence angle of the LED light source is relatively large, resulting in a complex subsequent optical system design and high costs.

[0003] In terms of improving the light emission collimation of a single micro-light source in a micro-LED array light source, atomic layer deposition (ALD) coating is used to deposit a DBR mirror layer on the side wall of the micro-LED to reflect the side emission of the LED chip back into the chip interior, allowing light to emit only from the surface of the LED chip. Limited by the total reflection phenomenon of light from an optically denser medium to an optically thinner medium, the emission angle on the surface of the LED chip is relatively small, improving the collimation, but a large amount of light is absorbed after multiple reflections within the chip, reducing the light output efficiency. Another common method is to fill the space between the chips in the micro-LED array light source with a reflective glue (such as an epoxy resin containing titanium oxide) to reflect the side emission of the LED chip back into the chip interior, allowing light to emit only from the surface of the LED chip. However, the light reflectivity of the traditional reflective glue layer is limited by material properties (such as the uniform dispersion of titanium oxide particles), making it difficult to achieve high-efficiency reflection across the entire wavelength band, resulting in the absorption of lateral light and relatively large lateral emission losses. At the same time, an external collimation lens is used to further improve the collimation. However, the collimation technology relies on an external optical lens to achieve collimation, resulting in a large lens volume and high costs. Moreover, due to the limited light collection angle, the light utilization rate is reduced, and the requirements for the layout accuracy of the LED chips are extremely strict, with poor adaptability.

[0004] In terms of preventing light crosstalk, the traditional method is to fill the space between the LED chips with a white glue with a high reflectivity. Although this method can reduce light crosstalk, a spacing of more than 200 μm is required, which cannot meet the layout requirements of a micro-LED array light source with a small spacing and high density below 100 μm, and has a low light extraction efficiency and poor light emission collimation, resulting in a poor anti-light crosstalk effect.

[0005] In summary, the existing technologies have the following three defects:

[0006] 1. The contradiction between controlling light utilization rate and light collimation:

[0007] Traditional reflection structures (such as planar reflection layers) are difficult to balance lateral light reflection and forward light collimation, resulting in a large divergence angle (usually > 120°), requiring additional optical elements for correction, increasing system complexity and cost, and reducing light utilization efficiency.

[0008] 2. Poor heat dissipation performance and material stability:

[0009] In high-power LED light sources, traditional reflective adhesive layers (such as epoxy resins) have poor heat resistance, are prone to yellowing after long-term use, and the reflectivity attenuation is significant. Although sulfide-based reflective materials have high conductivity, their chemical stability is poor, and they are prone to react with air or packaging materials, shortening the device life.

[0010] 3. It is impossible to balance anti-light crosstalk and light utilization efficiency:

[0011] Current technologies use the method of filling reflective adhesive between LED chips to reflect the side-emitted light back into the chips and then emit it from the front of the chips, improving the light collimation and reducing the light crosstalk between micro light sources. However, this causes light absorption after multiple reflections, reducing the light utilization efficiency. Summary of the Invention

[0012] The purpose of the present invention is to provide a Si packaging substrate with a light reflection structure and a light absorption structure and its preparation method to solve the problems of poor light utilization efficiency, light collimation, and anti-light crosstalk performance in the use of existing array micro light sources.

[0013] To achieve the above purpose, the present invention adopts the following technical solutions: A Si packaging substrate with a light reflection structure and a light absorption structure, including:

[0014] A silicon-based substrate, on whose end face several grooves are arranged in an array, and the longitudinal section of the groove is V-shaped;

[0015] An LED chip, which is positioned on the bottom surface of the groove through a conductive solder, with its light-emitting surface facing outward, and a light conversion layer covering the light-emitting surface;

[0016] A reflection layer, which is arranged on the wedge-shaped side surface of the groove and extends to the end face of the silicon-based substrate, and a passivation layer is arranged on the surface of the reflection layer and / or between the reflection layer and the end face of the silicon-based substrate;

[0017] A light absorption enclosure, which is arranged on the passivation layer outside the top of the groove, and is a continuous strip structure.

[0018] As a further description of the above technical solution:

[0019] The distance between adjacent LED chips is less than 100 μm.

[0020] As a further description of the above technical solution:

[0021] The conductive solder is a high thermal conductivity metal solder.

[0022] As a further description of the above technical solution:

[0023] The light conversion layer is a fluorescent glue or a ceramic fluorescent sheet.

[0024] As a further description of the above technical solution:

[0025] The reflective layer is composed of metal Al or Ag.

[0026] As a further description of the above technical solution:

[0027] The reflective layer is a composite reflective layer composed of metal Al, Ag and dielectric films SiO2, TiO2, Ta2O5.

[0028] As a further description of the above technical solution:

[0029] The light-absorbing enclosure is PI, PEEK or black glue.

[0030] The preparation method of the above Si encapsulation substrate includes the following steps:

[0031] S1. Silicon-based substrate treatment: A photoresist is coated on the surface of the silicon-based substrate to form a pattern, and the pattern is anisotropically etched by a KOH or TMAH solution to form a plurality of the grooves with inclined side walls;

[0032] S2. Reflective layer formation: A reflective substance is sputtered or evaporated on the side walls of the grooves to form the reflective layer;

[0033] S3. Chip fixing: The LED chip is welded and fixed at the bottom of the groove through the conductive solder, and a light conversion layer is arranged on the light-emitting surface of the outer end face of the LED chip;

[0034] S4. Passivation layer preparation: An oxide layer is deposited on the surface of the reflective layer to form a passivation layer;

[0035] S5. Light-absorbing enclosure formation: A light-absorbing substance is spin-coated on the silicon-based substrate and outside the grooves, and the continuous light-absorbing enclosure is formed by photolithography or laser cutting.

[0036] In summary, due to the adoption of the above technical solution, the present invention has the following beneficial effects compared with the prior art:

[0037] The silicon packaging substrate of the present invention is provided with a light reflection structure and a light absorption structure outside the LED chip, which improves the light utilization rate and prevents light crosstalk between micro-light source LED chips. The inclined groove is combined with a composite reflection layer composed of an Al and Ag metal reflection layer or a metal / dielectric layer, so that the lateral light is efficiently reflected to the light-emitting direction, improving the light extraction efficiency and light utilization rate. Combined with the absorption of stray light with a divergence angle > 30° by the light absorption enclosure and the conversion of the light emitted by the micro-light source by the light conversion layer, the half-peak width of the light source is reduced, the complexity of the subsequent light distribution lens is reduced, and the collimation of light is improved. It is applicable to precision lighting systems such as ADB and 3D printing light sources, while simplifying the production process and reducing product costs. The conductive solder is a high thermal conductivity metal solder, thereby improving the heat conduction ability between the LED chip and the silicon substrate and improving the heat dissipation performance of the micro-light source. The materials used for the silicon packaging substrate have high stability and service life, and stable optical properties. Description of the Drawings

[0038] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for use in the embodiments. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0039] Figure 1 It is a schematic structural diagram of an Si packaging substrate with a light reflection structure and a light absorption structure.

[0040] Figure 2 It is a schematic diagram of the processing state of an Si packaging substrate with a light reflection structure and a light absorption structure at step S2.

[0041] Figure 3 It is a schematic diagram of the processing state of an Si packaging substrate with a light reflection structure and a light absorption structure at step S4.

[0042] Figure 4 It is a schematic diagram of the processing state of an Si packaging substrate with a light reflection structure and a light absorption structure at step S5.

[0043] Figure 5 It is a process flow chart of the preparation method of an Si packaging substrate with a light reflection structure and a light absorption structure.

[0044] Legend Explanation:

[0045] 1. Silicon substrate; 2. Groove; 3. LED chip; 4. Conductive solder; 5. Light conversion layer; 6. Reflection layer; 7. Passivation layer; 8. Light absorption enclosure. Detailed Embodiments

[0046] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Components of the embodiments of the present invention described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations.

[0047] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0048] It should be noted that like reference numerals and letters denote like items in the following drawings. Therefore, once an item is defined in one drawing, it does not require further definition and explanation in subsequent drawings.

[0049] In the description of the embodiments of the present invention, it should be noted that the orientation or positional relationship indicated by terms such as "upper", "inner", etc. is based on the orientation or positional relationship shown in the drawings or the orientation or positional relationship in which the inventive product is habitually placed during use. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

[0050] In the description of the present invention, it should also be noted that unless otherwise clearly defined and limited, the terms "set", "install", "connect", and "couple" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, and can also be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0051] Please refer to Figures 1-5 , the present invention provides a technical solution: a Si packaging substrate with a light reflection structure and a light absorption structure, including:

[0052] A silicon-based substrate 1, on the end surface of which a plurality of grooves 2 are arranged in an array, and the longitudinal section of the groove 2 is V-shaped;

[0053] An LED chip 3, which is positioned on the bottom surface of the groove 2 through a conductive solder 4, with its light-emitting surface facing outward, and a light conversion layer 5 covers the light-emitting surface;

[0054] A reflective layer 6 is disposed on the wedge-shaped side surface of the groove 2 and extends to the end surface of the silicon-based substrate 1, and a passivation layer 7 is provided on the surface of the reflective layer 6 and / or between the reflective layer 6 and the end surface of the silicon-based substrate 1;

[0055] A light-absorbing enclosure 8 is disposed on the passivation layer 7 outside the top of the groove 2, and it is a continuous strip structure.

[0056] In the silicon encapsulation substrate of the present invention, a light reflection structure and a light absorption structure are disposed outside the LED chip, which improves the light utilization rate and prevents light crosstalk between micro-light source LED chips. Specifically, by disposing a reflective layer on the wedge-shaped side surface of the groove where the LED chip is disposed to improve the light extraction efficiency, and disposing a light-absorbing enclosure on the outer side of the groove and the upper edge of the reflection surface to absorb stray light, the light utilization rate and light collimation are significantly improved. It is applicable to precision lighting systems such as ADB and 3D printing light sources, simplifies the production process, and reduces the product cost.

[0057] The spacing between adjacent LED chips 3 is less than 100 μm to increase the distribution density of the micro-light source, thereby ensuring the lighting quality and achieving high-precision lighting.

[0058] The conductive solder 4 is a high-thermal-conductivity metal solder, thereby improving the heat conduction ability between the LED chip 3 and the silicon-based substrate 1 and improving the heat dissipation performance of the micro-light source.

[0059] The light conversion layer 5 is a fluorescent glue or a ceramic fluorescent sheet, which senses the light of a specific wavelength in the light beam emitted by the LED chip 3 and converts it into light of a target wavelength to achieve the function of wavelength conversion of light, thereby improving the light efficiency formed by the present light-emitting structure.

[0060] The reflective layer 6 is composed of metal Al or Ag. Alternatively, the reflective layer 6 is a composite reflective layer composed of metals Al, Ag and dielectric films SiO2, TiO2, Ta2O5.

[0061] The light-absorbing enclosure 8 is made of PI, PEEK or black glue, and it is used to absorb stray light with a large divergence angle to cooperate with the reflective layer 6 and balance the lateral light reflection and forward light collimation of the micro-light source.

[0062] The preparation method of the above Si encapsulation substrate with a light reflection structure and a light absorption structure includes the following steps:

[0063] S1. Silicon-based substrate treatment: Select a silicon-based substrate 1 with a specific crystal orientation that matches the micro-light source of the LED chip. Coat a photoresist on the surface of the silicon-based substrate 1 to form a pattern corresponding to the groove 2. Anisotropically etch this pattern with a KOH or TMAH solution to form several grooves 2 with inclined sidewalls, thereby ensuring the high-precision formation of grooves 2 with different shapes and reducing the difficulty of their formation. The wedge-shaped side surface of the groove 2 forms a characteristic angle structure according to the specific crystal orientation of the silicon-based substrate 1.

[0064] S2. Reflective layer formation: Sputter or evaporate a reflective material on the sidewalls of the groove 2 to form the reflective layer 6. Specifically, through physical vapor deposition techniques such as sputtering or evaporation deposition processes, a metal Al, Ag, or a composite reflective layer composed of the above metals and dielectric films SiO2, TiO2, Ta2O5 is formed on the surfaces of the silicon-based substrate 1 and the groove 2. The light reflection characteristics are optimized by precisely controlling the thickness and surface morphology of the reflective film layer.

[0065] S3. Chip fixation: Weld and fix the LED chip 3 to the bottom of the groove 2 through the conductive solder 4, and arrange a light conversion layer 5 on the light-emitting surface of the outer end face of the LED chip 3 to achieve independent control of the LED chip electrodes. The specific arrangement of the light conversion layer is to coat a fluorescent glue or attach a ceramic fluorescent sheet on the surface of the LED chip. By sensing the light with a specific wavelength in the light beam emitted by the LED chip 3 and converting it into light with a target wavelength, the function of wavelength conversion of light is realized, thereby improving the light efficiency formed by this light-emitting structure.

[0066] S4. Passivation layer preparation: Deposit an oxide layer on the surface of the reflective layer 6 to form a passivation layer 7 to protect the reflection interface of the dense dielectric reflective layer 6.

[0067] S5. Absorbing wall formation: Spin-coat an absorbing material on the silicon-based substrate 1 outside the groove 2. Specifically, using micro-nano processing technology, spin-coat PI, PEEK, or black glue at both ends of the top of the groove 2, and form the continuous absorbing wall 8 through photolithography or laser cutting.

[0068] In summary, due to the adoption of the above technical solutions, a Si packaging substrate with a light reflection structure and an absorbing structure and its preparation method in this embodiment have the following beneficial effects compared with the prior art:

[0069] The silicon encapsulation substrate of the present invention is provided with a light reflection structure and a light absorption structure outside the LED chip, which improves the light utilization rate and prevents light crosstalk between micro-light source LED chips. The inclined groove is combined with a composite reflection layer composed of an Al and Ag metal reflection layer or a metal / dielectric layer, so that the lateral light is efficiently reflected to the light-emitting direction, improving the light extraction efficiency and light utilization rate. Combined with the absorption of stray light with a divergence angle > 30° by the light absorption wall and the conversion of the light emitted by the micro-light source by the light conversion layer, the full width at half maximum of the light source is reduced, the complexity of the subsequent light distribution lens is reduced, and the collimation of light is improved. It is applicable to precision lighting systems such as ADB and 3D printing light sources, while simplifying the production process and reducing the product cost. The conductive solder is a high thermal conductivity metal solder, thereby improving the heat conduction ability between the LED chip and the silicon substrate and improving the heat dissipation performance of the micro-light source. The materials used for the silicon encapsulation substrate have high stability and service life, and stable optical properties.

[0070] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. A Si packaging substrate with a light reflection structure and a light absorption structure, characterized in that, Comprising: A silicon-based substrate, on whose end face a number of grooves are arranged in an array, and the longitudinal section of the groove is V-shaped; An LED chip, which is positioned on the bottom surface of the groove through a conductive solder, with its light-emitting surface facing outward, and a light conversion layer covering the light-emitting surface; A reflective layer, which is arranged on the wedge-shaped side surface of the groove and extends to the end face of the silicon-based substrate, and a passivation layer is provided on the surface of the reflective layer and / or between it and the end face of the silicon-based substrate; A light-absorbing enclosure, which is arranged on the passivation layer outside the top of the groove and is a continuous strip structure.

2. The Si packaging substrate with a light reflection structure and a light absorption structure according to claim 1, wherein The distance between adjacent LED chips is less than 100 μm.

3. The Si packaging substrate with a light reflection structure and a light absorption structure according to claim 1, wherein, The conductive solder is a high thermal conductivity metal solder.

4. The Si encapsulation substrate with a light reflection structure and a light absorption structure according to claim 1, characterized in that, The light conversion layer is a fluorescent glue or a ceramic fluorescent sheet.

5. The Si encapsulation substrate with a light reflection structure and a light absorption structure according to claim 1, wherein The reflective layer is composed of metal Al or Ag.

6. The Si packaging substrate with a light reflection structure and a light absorption structure according to claim 1, wherein The reflective layer is a composite reflective layer composed of metal Al, Ag and dielectric films SiO2, TiO2, Ta2O5.

7. The Si encapsulation substrate with a light reflection structure and a light absorption structure according to claim 1, characterized in that, The light-absorbing enclosure is PI, PEEK or black glue.

8. The manufacturing method of a Si packaging substrate with a light reflection structure and a light absorption structure according to claim 1, characterized in that, Including the following steps: S1. Silicon-based substrate treatment: A photoresist is coated on the surface of the silicon-based substrate to form a pattern, and the pattern is anisotropically etched by a KOH or TMAH solution to form a number of the grooves with inclined side walls; S2. Reflective layer forming: A reflective substance is sputtered or evaporated on the side wall of the groove to form the reflective layer; S3. Chip fixing: The LED chip is welded and fixed at the bottom of the groove through the conductive solder, and a light conversion layer is arranged on the light-emitting surface of the outer end face of the LED chip; S4. Passivation layer preparation: An oxide layer is deposited on the surface of the reflective layer to form the passivation layer; S5. Light-absorbing enclosure forming: A light-absorbing substance is spin-coated on the silicon-based substrate outside the groove, and the continuous light-absorbing enclosure is formed by photolithography or laser cutting.

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