A side-emitting LED chip-level packaging method

Abstract

The present invention provides a side-emitting LED chip-level packaging method, which first uses a heating wire in a lower mold to heat the fluorescent resin before it is completely solidified, and then uses a cooling part to cool it toward a heat dissipation metal plate to form a temperature gradient in the vertical direction of the fluorescent resin, thereby forming convex and concave surfaces on the surface of the fluorescent resin to form a roughened surface, and then stops the heating work of the heating wire, cools to room temperature, and completes the roughening and curing steps.

Description

Technical Field

[0001] The present invention relates to the field of LED packaging, belongs to the classification number H01L33 / 00, and specifically is a side-emitting LED chip-level packaging method. Background Art

[0002] CSP (Chip Scale Package) is composed of a flip chip in the center and fluorescent glue surrounding the flip chip. When in use, the CSP light source can be directly soldered to the substrate through solder to achieve light emission, eliminating the wire bonding process, thereby improving the packaging efficiency. The most significant advantage of CSP LED is its high luminous efficiency, but the single-sided CSP lamp beads currently on the market have some problems: 1. The white glue around the single-sided CSP light source in the prior art blocks the side light emission of the light-emitting chip, thereby reducing the brightness of the light source. 2. At the same time, because the white glue blocks the side light emission of the light-emitting chip, the light is reflected and refracted multiple times. In this process, light is converted into heat, resulting in a significant increase in heat generation, which reduces the reliability and safety of the light source, thereby shortening the life of the light source. Summary of the invention

[0003] In order to solve the above problems, the present invention provides a side-emitting LED chip-level packaging method, comprising the following steps:

[0004] (1) Using a precision chip arrangement machine, the chips are arranged into a 30×30 matrix on the die bonding film. The chip arrangement accuracy is required to be ±5μm, the angle deflection is less than 1°, and the spacing between chips is between 0.376 and 0.466μm. When arranging the chips, the chip electrodes face upward and the light-emitting surface of the chip contacts the die bonding film.

[0005] (2) The prefabricated B-Stage fluorescent film is stacked on the die-bonding film and the chip for lamination, and the total thickness is controlled to be 0.25 mm using a height setting sheet. After the hot pressing is completed, the film is placed in a 150° C. nitrogen oven for baking for 3 h;

[0006] (3) Use a cutting knife to perform horizontal and vertical cutting, and cut from the middle of the chip. The selected cutting machine is a diamond grinding wheel cutting machine with a rotation speed of 10000r / min and a cutting speed of 100mm / s;

[0007] (4) Using the prefabricated B-Stage white wall film to overlap the fluorescent film for hot pressing, using a height setting sheet to control the total thickness to 0.35 mm, after hot pressing, place the film in a 150° C. nitrogen oven for baking for 3 h;

[0008] (5) Use a cutting knife to make horizontal and vertical cuts. When cutting horizontally, cut along the side edge of the chip so that at least one side of each chip does not have the white wall film left. When cutting vertically, cut from the middle of the chip to divide the vertical white wall film into two parts along the center line.

[0009] The present invention further provides a side-emitting LED chip-level packaging method, comprising the following steps:

[0010] (1) Fixing a plurality of LED chips on a die-bonding film 10, wherein the plurality of LED chips are arranged in a 30×30 matrix, and the spacing between the chips is between 0.376 and 0.466 μm. When arranging the chips, the light-emitting surfaces of the plurality of LED chips face upward, and the electrodes thereof are in contact with the die-bonding film;

[0011] (2) coating the fluorescent resin on the solid crystal film and semi-curing it;

[0012] (3) forming a plurality of transverse and longitudinal grooves in the fluorescent resin by using a die-stamping tool, and simultaneously performing a roughening process and a curing process;

[0013] (4) Pressing a transparent waterproof layer onto the fluorescent resin, wherein the transparent waterproof layer fills the groove, and the thermal expansion coefficient of the transparent waterproof layer is greater than the thermal expansion coefficient of the fluorescent resin.

[0014] (5) Cutting is performed along the center line of the groove to obtain a monomerized LED packaging structure.

[0015] The present invention also provides a side-emitting LED chip-level packaging method, comprising the following steps:

[0016] (1) Fixing a plurality of LED chips on a die-bonding film 10, wherein the plurality of LED chips are arranged in a 30×30 matrix, and the spacing between the chips is between 0.376 and 0.466 μm. When arranging the chips, the light-emitting surfaces of the plurality of LED chips face upward, and the electrodes thereof are in contact with the die-bonding film;

[0017] (2) coating the fluorescent resin on the solid crystal film and semi-curing it;

[0018] (3) forming a plurality of transverse and longitudinal grooves in the fluorescent resin by using a die-stamping tool, and simultaneously performing a roughening process and a curing process;

[0019] (4) filling the groove with a scattering material, wherein the scattering rate of the scattering material is greater than the scattering rate of the fluorescent resin;

[0020] (5) Laminating a transparent waterproof layer on the fluorescent resin, wherein the transparent waterproof layer fills the groove, and the thermal expansion coefficient of the transparent waterproof layer is greater than the thermal expansion coefficient of the fluorescent resin;

[0021] (6) Cutting is performed along the center line of the groove to obtain a monomerized LED packaging structure.

[0022] According to an embodiment of the present invention, the step (3) specifically includes: placing the mold in a closed space, placing the workpiece to be roughened on the lower mold, and pressing the upper mold on the fluorescent resin, wherein the upper mold has a plurality of criss-cross protrusions, and the protrusions correspond to the grooves; pressing a heat dissipation metal plate on the upper mold; first heating the workpiece with the heating wire in the lower mold before the fluorescent resin is completely cured, and then cooling the workpiece toward the heat dissipation metal plate with the cooling part to form a temperature gradient in the vertical direction of the fluorescent resin, thereby forming convex and concave surfaces on the surface of the fluorescent resin to form a roughened surface, and then stopping the heating work of the heating wire and cooling the workpiece to room temperature to complete the roughening and curing steps. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1-7 Schematic diagram of the manufacturing process of CSP LED with double-sided light emission;

[0024] Figure 8-13 Schematic diagram of the manufacturing process of CSP LED with three-sided light emission;

[0025] Figure 14-18 Schematic diagram of the manufacturing process of five-sided CSP LED;

[0026] Fig.19 A cross-sectional view of a five-sided light-emitting LED package structure according to another embodiment;

[0027] Fig. 20 It is a schematic diagram of the atomization process of the fluorescent film surface according to the present invention. DETAILED DESCRIPTION

[0028] The purpose of the present invention is to provide a CSP LED manufacturing process for side-emitting and three-sided emitting

[0029] In order to achieve the purpose of the present invention, the following technical solutions are provided:

[0030] Two-sided lighting (single side)

[0031] 1. As Figure 1 As shown, the chip 2 is arranged into a 30×30 matrix using a precision chip arrangement machine, and the chip arrangement accuracy is required to be ±5μm, and the angle deflection is <1°. The spacing between chips is between 0.376 and 0.466μm. When arranging the chips, the electrode of chip 2 faces upward, and the light-emitting surface of the chip contacts the solid crystal film 1. The solid crystal film 1 is a double-sided sticky PET film with 2 to 5μm thick pyrolytic glue on both sides. One side of the solid crystal film 1 is tightly attached to the mask glass, and the other side is attached to the chip 2.

[0032] 2. Lay the prefabricated B-Stage fluorescent film 3 on the above workpiece, and use a height setting sheet to control the total thickness to 0.25mm. After hot pressing, bake in a 150℃ nitrogen oven for 3 hours. Figure 2 shown.

[0033] 3. Use a special cutter to cut it horizontally and vertically. The cutter used is a resin thin knife with a thickness of 0.1mm. Cut from the middle of the chip. The selected cutting machine is a diamond grinding wheel cutting machine with a speed of 10000r / min and a cutting speed of 100mm / s. Figure 3 As shown. Each chip cut Figure 4 shown.

[0034] 4. Then use the prefabricated B-Stage white wall film 4 to heat press the above workpiece, use the height setting plate to control the total thickness to 0.35mm, and bake it in a 150℃ nitrogen oven for 3 hours after the hot pressing is completed. The material of the white wall film is one or two of silicone plus titanium dioxide, epoxy resin plus titanium dioxide. Figure 5 shown.

[0035] 5. Use a cutting knife to make horizontal and vertical cuts. When cutting horizontally, cut along the side edge of the chip so that there is no white wall film left on one side of each chip. When cutting vertically, cut from the middle of the chip to divide the vertical white wall film into two parts along the center line. Figure 6 The final side-emitting CSP is as shown in Figure 7 shown.

[0036] Three-sided light

[0037] 1. Use a precision chip arrangement machine to arrange the chips 2 into a 30×30 matrix, requiring the chip arrangement accuracy to be ±5μm and the angle deflection to be <1°. The spacing between chips is between 0.376 and 0.466μm. When arranging the chips, the electrode of chip 2 faces upward, and the light-emitting surface of chip 2 contacts the solid crystal film. The solid crystal film 1 is a double-sided sticky PET film, both sides of which are coated with 2 to 5μm thick pyrolytic glue. One side of the solid crystal film 1 is tightly attached to the mask glass, and the other side is adhered to the chip. Figure 8 shown.

[0038] 2. Press the prefabricated B-Stage fluorescent film onto the above workpiece, and use a height setting sheet to control the total thickness to 0.25mm. After hot pressing, bake in a 150℃ nitrogen oven for 3 hours. Fig. 9 shown.

[0039] 3. Use a special cutting knife to cut it horizontally. The thickness of the cutting knife is 0.1mm. When cutting, cut from the middle of the chip. Fig.10 shown.

[0040] 4. Then use the prefabricated B-Stage white wall film to heat press the above workpiece, use the height setting plate to control the total thickness to 0.25mm, and bake in a 150℃ nitrogen oven for 3 hours after the hot pressing is completed. The material of the white wall film is one or two of silicone plus titanium dioxide, epoxy resin plus titanium dioxide. After the baking is completed, wipe the surface of the chip with alcohol to expose the fluorescent surface. Fig.11 shown.

[0041] 5. Finally, use a special cutting knife to make a longitudinal cut at a position 0.1mm away from the chip. At this time, the horizontal white wall film is removed and light can be emitted from both sides. Fig.12 Finally, a three-sided luminous CSP product is formed, as shown in Fig.13 shown.

[0042] The above method uses physical evaporation, electroplating, electroforming, chemical plating and other processes to produce two-sided and three-sided luminous products, effectively solving the problems of light source brightness and service life. The side luminous brightness is higher and the heat generation is lower. The CSP light decay and service life are also greatly improved.

[0043] The above two methods are to face the light-emitting surface downward (i.e., the side of the die-bonding film), which has the purpose of saving costs when preparing the two-side light-emitting and single-side light-emitting packaging structures. However, for the packaging structure with light-emitting on all four sides, this light-emitting surface facing downward is not conducive to the purpose of cost saving and simplified manufacturing process. For this reason, see the attached Figure 14-18 , a five-side light-emitting LED-CSP packaging method is introduced, which includes the following steps:

[0044] See also Fig.14 , multiple LED chips 11 are fixed on the solid crystal film 10, and the multiple LED chips 11 are arranged in a 30×30 matrix, and the chip arrangement accuracy is required to be ±5μm, and the angle deflection is <1°. The spacing between chips is between 0.376 and 0.466μm. When arranging the chips, the light-emitting surface of the chip 11 faces upward, and the electrode of the chip 11 contacts the solid crystal film.

[0045] See also Fig.15 , a fluorescent resin 12 is coated on the solid crystal film 10 and semi-cured.

[0046] See also Fig.16 , a plurality of transverse and longitudinal grooves 13 are formed in the fluorescent resin 12 by a die-casting tool, and a roughening treatment is performed (see Fig. 20 , see below for details), and at the same time, the fluorescent resin 12 is cured.

[0047] See also Fig.17, a transparent waterproof layer 14 is pressed onto the fluorescent resin 12, and the transparent waterproof layer 14 fills the groove 13. The transparent waterproof layer is an epoxy resin layer, a polyimide layer, etc., and in order to prevent warping, the thermal expansion coefficient of the transparent waterproof layer is greater than the thermal expansion coefficient of the fluorescent resin 12.

[0048] See also Fig.18 , cutting is performed along the center line of the groove 13 to obtain a monomeric LED packaging structure.

[0049] As a preferred structure, see Fig.19 After the fluorescent resin 12 is cured, the groove 13 is first filled with a scattering material 15, and then covered with a waterproof layer. At this time, the scattering rate of the scattering material 15 is greater than the scattering rate of the fluorescent resin 12, which can enhance the light emission from the side.

[0050] In order to ensure uniform light output, as mentioned above, the semi-cured fluorescent resin 12 needs to be roughened. For specific process, refer to Fig. 20 This is also the most important part, and the present invention will be introduced in detail in the following content.

[0051] like Fig. 20 The roughening process is carried out in a closed space 20. The solid crystal film 10 equipped with the LED chip 11 is placed on the lower mold 21. Before this, the LED chip 11 has been covered with a semi-cured fluorescent resin 12. The upper mold 24 is pressed on the fluorescent resin 12. The upper mold 24 has a plurality of criss-cross protrusions 25, which correspond to the grooves 13. The protrusions 25 are embedded in the fluorescent resin 12 to form the grooves 13; a heat dissipation metal plate 23 is pressed on the upper mold 24; wherein the top of the closed space 20 has a cooling portion 26, which can release a heat source (such as cooling gas) toward the heat dissipation metal plate 23, and a heating wire 22 is integrated inside the lower mold 21 for heating the fluorescent resin 12 for curing. When in use, the heating wire 22 is first used for heating. Before it is completely solidified, the cooling part 26 is cooled toward the heat dissipation metal plate 23 to form a temperature gradient in the vertical direction of the fluorescent resin 12, thereby forming convex and concave surfaces on the surface of the fluorescent resin 12 to form a roughened surface. Then, the heating work of the heating wire 22 is stopped and the resin is cooled to room temperature to complete the roughening and solidification steps.

[0052] Finally, it should be noted that: Obviously, the above embodiments are only examples for clearly explaining the present invention, and are not intended to limit the implementation methods. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from this are still within the scope of protection of the present invention.

Claims

1. A side-emitting LED chip-level packaging method, comprising the following steps: (1) fixing a plurality of LED chips on a die-bonding film, wherein the plurality of LED chips are arranged in a 30×30 matrix, and the spacing between the chips is between 0.376 and 0.466 μm. When arranging the chips, the light-emitting surfaces of the plurality of LED chips face upward, and the electrodes thereof are in contact with the die-bonding film; (2) coating the fluorescent resin on the solid crystal film and semi-curing it; (3) forming a plurality of transverse and longitudinal grooves in the fluorescent resin by using a die-stamping tool, and simultaneously performing a roughening process and a curing process; (4) filling the groove with a scattering material, wherein the scattering rate of the scattering material is greater than the scattering rate of the fluorescent resin; (5) Laminating a transparent waterproof layer on the fluorescent resin, wherein the transparent waterproof layer fills the groove, and the thermal expansion coefficient of the transparent waterproof layer is greater than the thermal expansion coefficient of the fluorescent resin; (6) Cutting is performed along the center line of the groove to obtain a monomerized LED packaging structure.

2. The side-emitting LED chip-level packaging method according to claim 1, characterized in that: The step (3) specifically includes: placing the mold in a closed space, placing the workpiece to be roughened on the lower mold, and pressing the upper mold on the fluorescent resin, wherein the upper mold has a plurality of criss-cross protrusions, and the protrusions correspond to the grooves; pressing a heat dissipation metal plate on the upper mold; first heating the workpiece with the heating wire in the lower mold before the fluorescent resin is completely cured, and then cooling the workpiece toward the heat dissipation metal plate with the cooling part to form a temperature gradient in the vertical direction of the fluorescent resin, thereby forming convex and concave surfaces on the surface of the fluorescent resin to form a roughened surface, and then stopping the heating work of the heating wire and cooling the workpiece to room temperature to complete the roughening and curing steps.

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