Packaging method of small-size LED light-emitting light source with integrated control chip

Abstract

This invention provides a method for packaging a small-sized LED light source with an integrated control chip, comprising the following steps: S1, forming a conductive circuit layer on a CMOS control chip; S2, fixing the bottom of the CMOS control chip to a substrate; connecting the pads of the CMOS control chip to the pads of the substrate with gold wires; S3, forming a dam inside the gold wires on the CMOS control chip, wherein the height of the top surface of the dam is lower than the height of the top surface of the LED chip; S4, forming a light-shielding adhesive layer by molding; S5, fixing the LED chip on the conductive circuit layer inside the dam to achieve electrical connection, and spraying adhesive powder outside the dam and on the outside of the LED chip to form a fluorescent adhesive layer, wherein the top surface of the fluorescent adhesive layer is lower than the top surface of the light-shielding adhesive layer, and a transparent adhesive layer is sprayed on the outside of the fluorescent adhesive layer. This invention achieves uniform formation of a fluorescent adhesive layer under the requirement of small-sized packaging, with good light emission effect and high production efficiency.

Description

Technical Field

[0001] This invention relates to the field of LED packaging technology, and more specifically to a method for packaging a small-sized LED light source with an integrated control chip. Background Technology

[0002] With the rapid development of miniaturized optoelectronic integrated devices and smart wearable devices, increasingly stringent requirements have been placed on small-sized and highly integrated light sources. Traditional light-emitting devices typically separate the driving circuit from the LED chip and interconnect them through external circuits. This not only occupies a large assembly space but also causes signal interference due to long leads and makes it difficult to further reduce the package size. It cannot meet the size and integration requirements of micro-sized optoelectronic systems. This is especially true for small-sized light source applications, such as automotive projection lights and AI glasses display lights, where the application scenarios are relatively small, requiring even smaller light sources to meet the requirements.

[0003] To improve integration, existing technologies are increasingly adopting a structure that integrates driver chips and light-emitting layers on a substrate to form a micro-light-emitting display module.

[0004] For example, patent application CN202510115792.5, published on April 18, 2025, discloses a micro-display panel comprising a substrate, a micro-light-emitting diode (LED) display chip, a phosphor layer, and an encapsulation layer. The LED display chip is located on the substrate, and its edges have metal pads electrically connected to areas of the substrate not covered by the LED display chip. The phosphor layer is located on the surface of the LED display chip, and the encapsulation layer covers the exposed areas of the substrate and the areas where the LED display chip is electrically connected to the substrate.

[0005] The above literature integrates the emissive layer and the driving circuit layer to form a micro-LED display chip. However, for a micro-LED display chip, the position of the emissive layer and the luminous intensity are fixed. If the parameters of the emissive chip need to be changed, the entire micro-LED display chip needs to be replaced. Furthermore, a transparent conductive layer is placed on top of the emissive layer instead of directly mixing light with the phosphor layer, resulting in poor light output. Additionally, the adhesive layer in the gold wire area is applied by dispensing, requiring the barrier height to be higher than the LED chip to prevent the adhesive from overflowing. The barrier height is also flush with the height of the adhesive layer in the gold wire area. To achieve a flush adhesive layer in the gold wire area using dispensing, the process involves dispensing, leveling, curing, and grinding. However, leveling after dispensing is affected by factors such as adhesive flow rate, resulting in low overall production efficiency. Furthermore, the fluorescent adhesive in the light-emitting area is applied by spraying. Since the fluorescent adhesive forms directly on the light-emitting area, if a thin layer is formed and the surface is smooth, unreliable adhesion between the fluorescent adhesive layer and the light-emitting area can occur, leading to poor light emission. Additionally, the fluorescent adhesive layer is simply laid flat on the light-emitting area, resulting in a relatively small contact area and a smooth surface, making it prone to peeling and unevenness. Summary of the Invention

[0006] This invention provides a method for packaging a small-sized LED light source with an integrated control chip, which can meet the packaging requirements of small size, has good uniformity of phosphor layer thickness, does not cause significant changes in emission color difference, and has high production efficiency.

[0007] To achieve the above objectives, the technical solution of the present invention is: a small integrated control chip A method for packaging a sized LED light source includes the following steps: S1. A conductive line layer electrically connected to the LED chip is formed on the top surface of the CMOS control chip; S2. Bond the bottom of the CMOS control chip to the substrate; connect the pads on the top surface of the CMOS control chip to the pads on the substrate using gold wires. S3. A dam is formed inside the gold wire of the CMOS control chip, and the height of the top surface of the dam is lower than the height of the top surface of the LED chip. S4. The mold bottom is connected to the top surface of the dam, and the mold is provided with a glue inlet corresponding to the outer side of the dam. A space for light-shielding glue is formed between the mold and the substrate. Light-shielding glue is injected through the glue inlet and leveled. Then, a light-shielding glue layer is formed by molding. The light-shielding glue layer covers the gold wire. The mold is then removed. S5. Fix LED chips on the conductive circuit layer inside the dam to achieve electrical connection, and spray adhesive powder outside the dam and on the outside of the LED chips to form a fluorescent adhesive layer. The top surface of the fluorescent adhesive layer is lower than the top surface of the light-shielding adhesive layer, and a transparent adhesive layer is sprayed on the outside of the fluorescent adhesive layer.

[0008] The above method uses a die-bonding process to fix the CMOS control chip onto the substrate, establishing a stable basic support structure. A wire bonding process is used to electrically connect the CMOS control chip to the substrate. Then, a dam is formed inside the gold wire, with the height of the dam lower than the height of the LED chip. A light-shielding adhesive is injected through the mold's inlet, covering the gold wire. A downward molding process then forms the adhesive layer within the containment space. This molding process ensures the adhesive is evenly distributed throughout the containment space, and the molding method eliminates air pockets within the adhesive. After removing the mold, the light-shielding layer is formed. A single molding process creates the light-shielding layer around the dam. The entire process is simple. Furthermore, the inner side of one end of the mold abuts against the dam, preventing the mold from being damaged by downward forces. The barrier will not come into contact with the CMOS control chip, thus preventing damage to the top surface of the CMOS control chip. At the same time, the height of the barrier increases the contact area with the phosphor layer when spraying phosphor later. It also separates the light-emitting area from the light-shielding adhesive layer from the bottom to prevent the influence of the light-shielding adhesive. Furthermore, because phosphor is sprayed on the LED chip, the phosphor layer can be made relatively thin and uniform, thereby improving the light emission uniformity of the entire light source. Even with a relatively thin phosphor layer, the height difference between the barrier and the LED chip results in a large contact area, ensuring the reliability of the phosphor layer connection and the reliability of light emission. The transparent adhesive layer protects the phosphor layer and also ensures a wider light emission angle when light passes through the transparent adhesive layer into the air, thereby improving the light emission effect.

[0009] Furthermore, in step S1, a conductive line layer for electrical connection of the LED chip is formed on the top surface of the CMOS control chip by deposition etching, or a conductive film with a conductive line layer is attached to the top surface of the CMOS control chip.

[0010] The above setup allows for the easy formation of a conductive circuit layer through deposition or application.

[0011] Furthermore, the LED chip has a size of 45μm.

[0012] The above settings limit the size of the LED chip, making a powder spraying process necessary to ensure uniform phosphor layer thickness and avoiding uneven coating caused by the dispensing process due to the chip being too small.

[0013] Furthermore, the top height of the dam described in step S2 is higher than the highest point of the gold line.

[0014] The above setup, with the dam higher than the highest point of the gold wire, prevents the light-blocking adhesive from affecting the gold wire during the molding process.

[0015] Furthermore, the process of forming the dam in step S3 includes mixing the light-shielding material with silicone and then forming the dam on the outside of the light-emitting area by dispensing the adhesive.

[0016] The above settings, by setting up a dam to limit the light-emitting area, can both limit the fluorescent adhesive layer and increase the contact area of ​​the fluorescent adhesive layer.

[0017] Furthermore, the mold includes an inwardly recessed mold body, with a baffle corresponding to the dam on the inner side of one end of the mold body. The baffle and the outer wall of the mold body form a receiving space, and the bottom of the baffle is higher than the bottom of the outer wall of the mold body. A glue inlet is provided in the receiving space. A cover plate is connected to the inner side of the baffle, and both sides of the cover plate are connected to the upper end of the baffle. The height between the bottom of the cover plate and the bottom of the baffle is greater than the height of the LED chip.

[0018] The above configuration creates a receiving space on the outer side of the mold, and a glue inlet is provided at the top of the receiving space. Light-shielding glue is injected through the glue inlet. A height difference is formed between the bottom of the outer wall of the mold body and the baffle, so that after the mold covers the dam, it can abut against the top of the dam. This can block the light-shielding glue and prevent the mold from directly contacting the top of the CMOS chip, which could cause damage.

[0019] Furthermore, in step S5, the spraying powder comprises mixing 10% phosphor powder, 85% epoxy resin and 5% wet agent by weight, and then spraying the powder back and forth more than twice to form a phosphor adhesive layer of 10-50 micrometers, with the phosphor powder having a particle size of 4-5 micrometers.

[0020] The above setup ensures uniformity and thinness of each powder spray by mixing fluorescent powder with epoxy resin adhesive and a wetting agent and then spraying the powder back and forth, while also ensuring the uniformity of the entire fluorescent adhesive layer.

[0021] Furthermore, step S5, "spraying a transparent adhesive layer on the outside of the fluorescent adhesive layer", includes: spraying a transparent adhesive layer on top of the light-shielding adhesive layer and the fluorescent adhesive layer using a spraying device and curing it to form a transparent adhesive layer, wherein the transparent adhesive layer is made of epoxy resin.

[0022] The above setup involves forming a transparent adhesive layer using spraying equipment, a simple process.

[0023] Furthermore, step S4, "injecting light-shielding adhesive through the injection port and leveling it before forming a light-shielding adhesive layer by molding," includes: determining the first position of the top surface of the CMOS control chip corresponding to the mold accommodating space, and determining the volume of the accommodating space in the mold and the first volume corresponding to the first position of the mold accommodating space; firstly injecting the first volume of light-shielding adhesive through the injection port, allowing the first light-shielding adhesive layer to flow in the accommodating space for a preset time; then injecting the second volume of light-shielding adhesive through the injection port and leveling it; the second volume is equal to the difference between the volume of the accommodating space and the first volume; molding from the top down of the mold; curing the light-shielding adhesive to form a light-shielding adhesive layer; and removing the mold.

[0024] The above configuration involves the light-shielding adhesive being formed in two stages within the containment space. The first stage allows the light-shielding adhesive to cover most of the gold wires and the portion where the gold wires connect to the substrate. Then, the second stage involves injecting the light-shielding adhesive to cover the upper end of the gold wires. This reduces the impact of a single injection of the light-shielding adhesive on the pads at both ends of the gold wires during the flow process, thereby improving the reliability of the gold wire connection.

[0025] Furthermore, the height of the top surface of the fluorescent adhesive layer is 5-20 micrometers lower than the height of the top surface of the light-shielding adhesive layer, and the height of the LED chip is 5-10 micrometers higher than the height of the dam.

[0026] The above settings, through the adjustment of the height difference, enable the fluorescent adhesive layer to adhere more reliably without excessively increasing its thickness. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of the LED light source of the present invention.

[0028] Figure 2 This is a schematic diagram of the process of the present invention.

[0029] Figure 3 This is a diagram illustrating the packaging process of the present invention.

[0030] Figure 4 This is a structural diagram of the mold used in this invention.

[0031] Figure 5 This is another perspective view of the mold in this invention.

[0032] Figure 6 for Figure 5 Sectional view of AA.

[0033] Figure 7 This is a schematic diagram of the structure of the mold covering the substrate in this invention.

[0034] 1-Substrate; 2-CMOS chip; 3-Silver paste; 4-Gold wire; 5-LED chip; 6-Fluorescent adhesive layer; 7-Damage; 8-Light-shielding adhesive layer; 9-Mold; 90-Mold body; 91-Baffle; 92-Accommodation space; 93-Cover plate; 921-Glue inlet; 10-Transparent adhesive layer. Detailed Implementation

[0035] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0036] like Figures 1 to 7 As shown, a method for packaging a small-sized LED light source with an integrated control chip includes a substrate 1, a CMOS chip 2, and an RGB chip 5, and further includes the following steps: S1. A conductive line layer electrically connected to the LED chip is formed on the top surface of the CMOS control chip. In step S1, the conductive line layer electrically connected to the LED chip is formed on the top surface of the CMOS control chip by deposition etching or by attaching a conductive film with the conductive line layer to the top surface of the CMOS control chip. In this embodiment, the CMOS control chip is a chip that provides switching drive for multiple LED chips. It is an existing chip. The top of the chip is provided with two pads connected to the external substrate 1, and the conductive line layer is connected to the internal circuit layer of the CMOS control chip 2 by drilling or wire bonding.

[0037] S2. The bottom of the CMOS control chip 2 is die-bonded onto the substrate 1; the pads on the top surface of the CMOS control chip 2 are connected to the pads on the substrate 1 via gold wire; during the die-bonding process, the bottom of the CMOS control chip 2 is fixed onto the substrate 1, and by using a die-bonding device, silver paste 3 or insulating glue and other adhesive materials are applied to adhere and solidify the bottom surface of the CMOS control chip 2 to the predetermined position on the substrate 1, thus establishing a stable basic support structure and ensuring the physical connection between the CMOS control chip 2 and the substrate 1.

[0038] S3. A dam 7 is formed inside the gold wire of the CMOS control chip 2, and the height of the top surface of the dam 7 is lower than the height of the top surface of the LED chip 5. The process of forming the dam 7 in step S3 includes mixing the light-shielding material with silicone and then forming the dam on the outside of the light-emitting area by dispensing. The light-shielding material is such as black powder.

[0039] The LED chip 5 is fixed on the CMOS control chip 2, and the LED chip 5 forms a light-emitting area on the CMOS control chip 2. The light-emitting area includes two or more LED chips 5. The LED chip 5 is electrically connected to the CMOS control chip 2, so that the CMOS control chip 2 transmits a driving signal to the LED chip 5 through its internal driving circuit to control the light emission of the LED chip 5. After the LED chip 5 is fixed on the CMOS chip 2, the light-emitting points on it constitute the light-emitting area. The size of each LED chip is 45μm, and the top height of the dam 7 is higher than the highest point of the gold wire 4, so that the gold wire 4 is physically protected in subsequent processes. At the same time, the height of the dam 7 is lower than the height of the LED chip 5, so that the phosphor layer is formed in the subsequent process. S4. Form a light-shielding adhesive layer 8. The light-shielding adhesive layer 8 is formed by the inner side of the bottom of the mold 9 and the top surface of the dam 7. The mold 9 is provided with an adhesive inlet 921 corresponding to the outer side of the dam 7. A light-shielding adhesive receiving space 91 is formed between the mold 9 and the substrate 1. The light-shielding adhesive is injected through the adhesive inlet 921 and leveled. The light-shielding adhesive layer 8 is formed by molding. The light-shielding adhesive layer 8 covers the gold wire 4. The mold 9 is then removed. S5. An LED chip 5 is fixed on the conductive circuit layer inside the dam 7 to achieve electrical connection. A fluorescent adhesive layer 6 is formed by spraying adhesive powder onto the outside of the dam 7 and the outside of the LED chip 5. The top surface of the fluorescent adhesive layer 6 is lower than the top surface of the light-shielding adhesive layer 8. A transparent adhesive layer 9 is sprayed onto the outside of the fluorescent adhesive layer 6. In this embodiment, the adhesive powder spraying in step S5 involves mixing 10% fluorescent powder, 85% epoxy resin, and 5% wettable agent by weight, and then spraying the mixture back and forth twice or more using a powder spraying device to form a fluorescent adhesive layer of 10-50 micrometers. The particle size of the fluorescent powder is 4-5 micrometers.

[0040] The step S5, "spraying a transparent adhesive layer 10 on the outside of the fluorescent adhesive layer 6", includes: spraying a transparent adhesive layer on top of the light-shielding adhesive layer 8 and the fluorescent adhesive layer 6 using a spraying device and curing it to form a transparent adhesive layer 10, wherein the transparent adhesive layer 10 is made of epoxy resin.

[0041] The height of the top surface of the fluorescent adhesive layer 6 is 5-20 micrometers lower than the height of the top surface of the light-shielding adhesive layer 8, and the height of the LED chip 5 is 5-10 micrometers higher than the height of the dam 7.

[0042] like Figure 4-7As shown, the mold 9 includes an inwardly recessed mold body 90. A baffle 91 corresponding to the dam 7 is provided on the inner side of one end of the mold body 90. The baffle 91 and the outer wall of the mold body 90 form a receiving space 92, and the bottom height of the baffle 91 is higher than the bottom height of the outer wall of the mold body 90. A glue inlet 921 is provided on the receiving space 92. A cover plate 93 is connected to the inner side of the baffle. The two sides of the cover plate 93 are respectively connected to the upper end of the baffle 91. The height between the bottom of the cover plate 93 and the bottom of the baffle 91 is greater than the height of the LED chip 5. In this embodiment, four glue inlets 921 are provided, which are located on the four sides of the receiving space.

[0043] Step S4, "injecting light-shielding adhesive through the injection port 921 and leveling it before forming a light-shielding adhesive layer by molding," includes: determining the first position B of the mold accommodating space 91 corresponding to the top pad 11 of the CMOS control chip 2, and determining the volume of the accommodating space 91 in the mold 9 and the first volume corresponding to the first position B of the mold accommodating space. The first volume is obtained by subtracting the volume of the CMOS control chip located in the accommodating space from the product of the height corresponding to the first position B and the length and width of the accommodating space. The volume of the CMOS control chip located in the accommodating space is obtained by multiplying the length, height, and width of the CMOS control chip extending into the accommodating space. First, inject the first volume of the first light-shielding adhesive through the injection port 921. After the first light-shielding adhesive layer flows within the containment space for a preset time, a second volume of light-shielding adhesive is injected through the inlet 921 and leveled. The second volume is equal to the difference between the volume of the containment space 91 and the first volume. The volume of the containment space 91 is the sum of the volumes of the containment cavities formed by each side of the entire containment space. The volume of each containment cavity is the product of the height, length, and width of the containment cavity. After molding from above the mold 9 downwards, specifically by pressing the lower mold down onto the upper mold, the light-shielding adhesive is cured to form the light-shielding adhesive layer 8. The mold 9 is then removed. To further ensure the reliability of the entire formation, the light-shielding adhesive at the inlet position is cut off after removing the mold 9 to form a flat top surface of the light-shielding adhesive.

[0044] The working principle of this invention is as follows: A CMOS control chip 2 is fixed onto a substrate using a die-bonding process, establishing a stable basic support structure. A wire bonding process is used to electrically connect the CMOS control chip 2 to the substrate 1. A dam 7 is then formed inside the gold wire, with the height of the dam 7 lower than the height of the LED chip 5. Light-shielding adhesive is injected through the inlet 921 of the mold 9, covering the gold wire. A downward molding process forms a light-shielding adhesive layer 8 within the containment space. During molding, the light-shielding adhesive is evenly distributed to each space, and the molding method eliminates air pockets within the adhesive. After removing the mold 9, the light-shielding adhesive layer 8 is formed. The light-shielding adhesive layer 8 around the dam can be formed in a single molding process. The entire process is simple. Furthermore, the inner side of one end of the mold 9 abuts against the dam 7, preventing the molding process from malfunctioning. When subjected to downward force, the mold will not come into contact with the CMOS control chip 2, thus preventing damage to the top surface of the CMOS control chip 2. At the same time, the height of the dam increases the contact area with the phosphor layer when phosphor is sprayed later. It also separates the light-emitting area from the light-shielding adhesive layer from the bottom to prevent the influence of the light-shielding adhesive. Furthermore, since phosphor is sprayed on the LED chip 5, the phosphor layer can be made relatively thin and uniform, thereby improving the light emission uniformity of the entire light source. Even with a relatively thin phosphor layer, the height difference between the dam and the LED chip 5 results in a large contact area, ensuring the reliability of the phosphor layer connection and the reliability of light emission. The transparent adhesive layer protects the phosphor layer and also ensures a wider light emission angle when light passes through the transparent adhesive layer 10 into the air, thereby improving the light emission effect.

Claims

1. A method for packaging a small-sized LED light source with an integrated control chip, comprising a substrate, a CMOS chip, and an RGB chip, characterized in that: It also includes the following steps: S1. A conductive line layer electrically connected to the LED chip is formed on the top surface of the CMOS control chip; S2. Bond the bottom of the CMOS control chip to the substrate; connect the pads on the top surface of the CMOS control chip to the pads on the substrate using gold wires. S3. A dam is formed inside the gold wire of the CMOS control chip, and the height of the top surface of the dam is lower than the height of the top surface of the LED chip. S4. The mold bottom is connected to the top surface of the dam, and the mold is provided with a glue inlet corresponding to the outer side of the dam. A space for light-shielding glue is formed between the mold and the substrate. Light-shielding glue is injected through the glue inlet and leveled. Then, a light-shielding glue layer is formed by molding. The light-shielding glue layer covers the gold wire. The mold is then removed. S5. Fix LED chips on the conductive circuit layer inside the dam to achieve electrical connection, and spray adhesive powder outside the dam and on the outside of the LED chips to form a fluorescent adhesive layer. The top surface of the fluorescent adhesive layer is lower than the top surface of the light-shielding adhesive layer, and a transparent adhesive layer is sprayed on the outside of the fluorescent adhesive layer.

2. The method for packaging a small-sized LED light source with an integrated control chip according to claim 1, characterized in that: In step S1, a conductive line layer for electrical connection of the LED chip is formed on the top surface of the CMOS control chip by deposition etching, or a conductive film with a conductive line layer is attached to the top surface of the CMOS control chip.

3. The packaging method for a small-size light source according to claim 1, characterized in that: The LED chip has a size of 45μm.

4. The method for packaging a small-sized LED light source with an integrated control chip according to claim 1, characterized in that: The top of the dam described in step S2 is higher than the highest point of the gold line.

5. The method for packaging a small-sized LED light source with an integrated control chip according to claim 1, characterized in that: The process of forming the dam in step S3 includes mixing the light-shielding material with silicone and then forming the dam on the outside of the light-emitting area by dispensing the adhesive.

6. The method for packaging a small-sized LED light source with an integrated control chip according to claim 1, characterized in that: The mold includes an inwardly recessed mold body. A baffle corresponding to the dam is provided on the inner side of one end of the mold body. The baffle and the outer wall of the mold body form a receiving space, and the bottom of the baffle is higher than the bottom of the outer wall of the mold body. A glue inlet is provided on the receiving space. A cover plate is connected to the inner side of the baffle. The two sides of the cover plate are connected to the upper end of the baffle, and the height between the bottom of the cover plate and the bottom of the baffle is greater than the height of the LED chip.

7. The method for packaging a small-sized LED light source with an integrated control chip according to claim 1, characterized in that: In step S5, the spraying powder consists of mixing 10% fluorescent powder, 85% epoxy resin and 5% wet agent by weight, and then spraying the powder back and forth more than twice to form a fluorescent adhesive layer of 10-50 micrometers. The particle size of the fluorescent powder is 4-5 micrometers.

8. The method for packaging a small-sized LED light source with an integrated control chip according to claim 1, characterized in that: The step S5, "spraying a transparent adhesive layer on the outside of the fluorescent adhesive layer", includes: spraying a transparent adhesive layer on top of the light-shielding adhesive layer and the fluorescent adhesive layer using a spraying device and curing it to form a transparent adhesive layer, wherein the transparent adhesive layer is made of epoxy resin.

9. The method for packaging a small-sized LED light source with an integrated control chip according to claim 1, characterized in that: Step S4, "injecting light-shielding adhesive through the injection port and leveling it before molding to form a light-shielding adhesive layer," includes: determining the first position of the top surface of the CMOS control chip corresponding to the mold accommodating space, and determining the volume of the accommodating space in the mold and the first volume corresponding to the first position of the mold accommodating space; firstly injecting the first volume of light-shielding adhesive through the injection port, allowing the first light-shielding adhesive layer to flow in the accommodating space for a preset time; then injecting the second volume of light-shielding adhesive through the injection port and leveling it; the second volume is equal to the difference between the volume of the accommodating space and the first volume; molding from top to bottom of the mold; curing the light-shielding adhesive to form a light-shielding adhesive layer; and removing the mold.

10. A method for packaging a small-sized LED light source with an integrated control chip according to claim 1, characterized in that: The height of the top surface of the fluorescent adhesive layer is 5-20 micrometers lower than the height of the top surface of the light-shielding adhesive layer, and the height of the LED chip is 5-10 micrometers higher than the height of the dam.

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