Mini LED chip packaging method

Abstract

The invention discloses a Mini LED chip packaging method. The method comprises the following steps: dispensing a hydrophobic coating composition on a substrate on the periphery of each Mini LED chip, and carrying out hot baking pretreatment to form a hydrophobic coating; the coating composition comprises organic fluorine resin, a surfactant and a solvent; and coating a layer of packaging surface glue on the pre-processed Mini LED chip substrate, baking and curing, and shrinking the packaging surface glue into an independent packaging unit by taking the Mini LED chip as a center to realize independent packaging of the Mini LED chip. A hydrophobic coating composition is dispensed on a substrate on the periphery of each Mini LED chip in advance to form a hydrophobic coating, then packaging surface glue is coated on the whole Mini LED chip substrate, the packaging surface glue is shrunk in the baking and curing process, and independent packaging of the Mini LED chips is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of Mini LED chip packaging, and in particular to a Mini LED chip packaging method. Background Art

[0002] Currently, electronic products on the market primarily use LED backlights. As electronic products evolve, people's expectations for them are becoming increasingly demanding. The brightness, contrast, color, and ultimate display quality of traditional LED backlights are no longer up to par. Mini LED, an upgraded version of LED, utilizes smaller LED chips, offering higher brightness, contrast, better color reproduction, and more refined display effects. It is gradually being adopted in televisions, computer monitors, mobile phones, tablets, and other fields.

[0003] Mini LED packaging technology, particularly for electronic products sized NB and below, primarily utilizes a fill dispensing process, whereby encapsulation adhesive is directly applied to the entire substrate and then cured for encapsulation. However, with this packaging process, if a single defective chip is found, the encapsulation adhesive on the chip's surface must be removed during rework before the chip is repaired. After the chip is repaired, the encapsulation adhesive is then reapplied. However, the color difference between the reapplied and original encapsulation adhesive can result in a distinct demarcation line on the display. Therefore, currently, if a single defective chip is found, the entire substrate must be scrapped.

[0004] Therefore, it is of great significance to research and develop an independent packaging method for Mini LED chips so as to realize the repair of individual chips and avoid the problem of individual chip defects causing the entire substrate to be scrapped. Summary of the Invention

[0005] In response to the deficiencies in the prior art, the present invention provides a Mini LED chip packaging method. First, a hydrophobic coating composition is spot-coated on the substrate around each Mini LED chip to form a hydrophobic coating, and then a packaging surface adhesive is coated on the entire substrate. Since the surface tension of the packaging surface adhesive is much greater than the surface tension of the hydrophobic coating composition, the packaging surface adhesive shrinks around the Mini LED chip during low-temperature baking to form an independent packaging unit, thereby realizing independent packaging of the Mini LED chip. This facilitates subsequent individual repair and repackaging of individual chips when they are defective, avoiding the entire substrate from being scrapped and increasing the service life of the LED display.

[0006] In order to solve the above technical problems, the present invention provides a Mini LED chip packaging method, comprising the following steps:

[0007] S1. Apply a hydrophobic coating composition on the substrate around each Mini LED chip and perform a heat baking pretreatment to form a hydrophobic coating, with a gap of 500-1000 μm between the side of the Mini LED chip and the hydrophobic coating;

[0008] Wherein, the coating composition comprises, by mass, 5-10 parts of an organic fluorine resin, 0.05-10 parts of a surfactant, and 80-95 parts of a solvent;

[0009] S2. Apply a layer of packaging surface glue on the pre-treated Mini LED chip substrate and bake and cure it. The packaging surface glue shrinks into an independent packaging unit with the Mini LED chip as the center to achieve independent packaging of the Mini LED chip.

[0010] The present invention pre-coats a hydrophobic coating composition with ultra-low surface tension on the substrate around each Mini LED chip, forms a hydrophobic coating through thermal baking, and then coats the entire Mini LED chip substrate with encapsulation adhesive. During the baking and curing process, the encapsulation adhesive shrinks on the hydrophobic coating with the Mini LED chip without the hydrophobic coating as the center, and shrinks to the substrate without the hydrophobic coating. The encapsulation adhesive on the surface of each Mini LED chip forms a gap on the hydrophobic coating, thereby realizing the individual packaging of the Mini LED chip. When a single Mini LED chip is defective, only this independent unit needs to be removed and repaired, without affecting the adjacent units, greatly reducing the cost of chip repair and at the same time increasing the service life of the LED display.

[0011] Furthermore, in S1, the general structural formula of the organic fluorine resin is:

[0012]

[0013] Wherein, n is an integer greater than 0; R1 and R2 are independently selected from one or more of hydrogen, benzene ring, C1-C4 alkyl, C1-C4 fatty acid, and C1-C3 fatty alcohol.

[0014] Furthermore, the molecular weight of the organic fluorine resin is 10w-18w, and the PDI is 1.2-1.8.

[0015] Furthermore, the preparation method of the organic fluorine resin is as follows: by weight, 30-50 parts of an organic fluorine monomer, 150-180 parts of a solvent N,N-dimethylformamide (DMF), and 0.1-0.5 parts of a catalyst dibenzoyl peroxide (BPO) are mixed, and the mixture is reacted at a temperature of 120-150° C. for 8-12 hours to obtain an organic fluorine resin;

[0016] Wherein, the structural formula of the organic fluorine monomer is: The hydrophobic coating composition composed of the organic fluorine resin has ultra-low surface tension.

[0017] Furthermore, in S1, the surface tension of the hydrophobic coating composition is 10-15 mN / m, which is much lower than that of conventional encapsulation adhesive, so that the encapsulation adhesive can slowly shrink into independent spacer units during the low-temperature baking stage.

[0018] Furthermore, in S1, the heat baking temperature is 80-150° C. and the time is 10-60 minutes.

[0019] Furthermore, in S2, the baking and curing is divided into two stages:

[0020] The first stage of baking is at a temperature of 60-100°C and a time of 30-60 minutes;

[0021] The second stage of baking is at a temperature of 100-150°C for 60-180 minutes. Preferably, the first stage of baking is at a temperature of 70-90°C, and the second stage of baking is at a temperature of 130-150°C. The encapsulation adhesive slowly shrinks into independent spacer units during the first low-temperature baking stage and solidifies into independent cells during the second high-temperature baking stage, achieving independent packaging.

[0022] Furthermore, in S1, the dot coating thickness of the hydrophobic coating composition is 10-50 μm; in S2, the coating thickness of the encapsulation surface adhesive is 200-260 μm.

[0023] Furthermore, in S1, the surfactant is Gemini fatty alcohol polyoxyethylene ether.

[0024] Furthermore, in S1, the solvent is selected from one or more of n-butanol, isobutanol, 2-methyl-1-butanol, isopentanol, 2,3-dimethyl-1-butanol, 4-methyl-2-pentanol, isohexanol, isoheptanol, 1-octanol, 1-nonanol and 1-decanol.

[0025] Furthermore, in S2, the packaging surface adhesive is a silicone packaging adhesive or an epoxy resin packaging adhesive.

[0026] Beneficial effects of the present invention:

[0027] The present invention pre-coats a hydrophobic coating composition on the substrate around each Mini LED chip to form a hydrophobic coating, and then applies a packaging surface glue on the entire Mini LED chip substrate. The packaging surface glue shrinks during the baking and curing process to achieve individual packaging of the Mini LED chip.

[0028] When a single Mini LED chip on the Mini LED chip substrate packaged by the method of the present invention is defective, it is only necessary to remove this independent unit for repair without affecting adjacent units, thereby greatly reducing the cost of chip repair and improving the service life of the LED display.

[0029] The present invention adds an organic fluorine resin to the hydrophobic coating composition to obtain a composition with low surface tension, thereby achieving an excellent hydrophobic effect, thereby realizing the shrinkage of the packaging surface glue during the low-temperature baking stage, and at the same time, the coating composition has high thermal stability and chemical stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solution of the present invention, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0031] Figure 1 2. FIG. 1 is a top view of the Mini LED chip substrate obtained by the packaging method of the present invention;

[0032] Figure 2 2 is a schematic cross-sectional view of a single Mini LED chip substrate of the present invention;

[0033] Explanation of the numbers in the figure: 1. Mini LED chip, 2. Packaging surface adhesive, 3. Hydrophobic coating, 4. Substrate. DETAILED DESCRIPTION

[0034] The following will provide a clear and complete description of the technical solutions of the present invention in conjunction with specific embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0035] This embodiment provides a Mini LED chip packaging method, including the following steps:

[0036] S1. Apply a hydrophobic coating composition on the substrate around each Mini LED chip and perform a heat baking pretreatment to form a hydrophobic coating, with a gap of 500-1000 μm between the side of the Mini LED chip and the hydrophobic coating;

[0037] Wherein, the coating composition comprises, by mass, 5-10 parts of an organic fluorine resin, 0.05-10 parts of a surfactant, and 80-95 parts of a solvent;

[0038] S2. Apply a layer of packaging adhesive on the pre-treated Mini LED chip substrate and bake and cure it. The packaging adhesive shrinks into an independent packaging unit with the Mini LED chip as the center, thus realizing independent packaging of the Mini LED chip. Figure 1-2 The hydrophobic coating 3 is located on the substrate 4 at the periphery of each Mini LED chip 1, and the encapsulation adhesive 2 shrinks in the gap near the Mini LED chip 1 where there is no hydrophobic coating, forming a separate package for the Mini LED chip 1. It can be seen that in this embodiment, a hydrophobic coating composition with ultra-low surface tension is pre-applied on the substrate at the periphery of each Mini LED chip, and a hydrophobic coating is formed by thermal baking. Subsequently, the encapsulation adhesive is applied to the entire Mini LED chip substrate. During the baking and curing process, the encapsulation adhesive shrinks on the hydrophobic coating with the Mini LED chip without the hydrophobic coating as the center, shrinking to the substrate without the hydrophobic coating. The encapsulation adhesive on the surface of each Mini LED chip forms a gap on the hydrophobic coating, realizing the separate packaging of the Mini LED chip. When a single Mini LED chip is defective, only the independent unit needs to be removed and repaired, without affecting the adjacent units, which greatly reduces the cost of chip repair and improves the service life of the LED display.

[0039] As a preferred embodiment, in S1, the general structural formula of the organic fluorine resin is:

[0040]

[0041] Wherein, n is an integer greater than 0; R1 and R2 are independently selected from one or more of hydrogen, benzene ring, C1-C4 alkyl, C1-C4 fatty acid, and C1-C3 fatty alcohol; the molecular weight of the organic fluorine resin is 10w-18w, and the PDI is 1.2-1.8.

[0042] Specifically, the preparation method of the organic fluorine resin is as follows: by weight, 30-50 parts of an organic fluorine monomer, 150-180 parts of a solvent N,N-dimethylformamide (DMF), and 0.1-0.5 parts of a catalyst dibenzoyl peroxide (BPO) are mixed, and the mixture is reacted at a temperature of 120-150° C. for 8-12 hours to obtain the organic fluorine resin;

[0043] Wherein, the structural formula of the organic fluorine monomer is: The hydrophobic coating composition composed of the organic fluorine resin has an ultra-low surface tension of 10-15mN / m, which is much lower than that of conventional encapsulation adhesives, so that the encapsulation adhesives can slowly shrink into independent spacer units during the low-temperature baking stage.

[0044] As a preferred embodiment, in S1, the heat baking temperature is 80-150°C and the time is 10-60 minutes; in S2, the baking and curing is divided into two stages: the first stage baking temperature is 60-100°C and the time is 30-60 minutes; the second stage baking temperature is 100-150°C and the time is 60-180 minutes; preferably, the first stage baking temperature is 70-90°C and the second stage baking temperature is 130-150°C. The packaging surface glue slowly shrinks into independent spacer units during the low-temperature baking stage of the first stage, and solidifies into independent cells during the high-temperature baking stage of the second stage, realizing independent packaging.

[0045] As a preferred embodiment, in S1, the dot coating thickness of the hydrophobic coating composition is 10-50 μm; in S2, the coating thickness of the encapsulation surface adhesive is 200-260 μm.

[0046] As a preferred embodiment, in S1, the surfactant is Gemini fatty alcohol polyoxyethylene ether; the solvent is selected from one or more of n-butanol, isobutanol, 2-methyl-1-butanol, isopentanol, 2,3-dimethyl-1-butanol, 4-methyl-2-pentanol, isohexanol, isoheptanol, 1-octanol, 1-nonanol and 1-decanol.

[0047] As a preferred embodiment, in S2, the packaging surface adhesive is a silicone packaging adhesive or an epoxy resin packaging adhesive.

[0048] Example 1

[0049] This embodiment relates to a method for preparing an organic fluorine resin, comprising the following steps:

[0050] An organic fluorine monomer and DMF were added to the reaction vessel in sequence, stirred evenly, and then heated to 120°C. BPO was then added and reacted for 8 hours to obtain an organic fluorine resin. The content of each component by mass and the molecular weight and PDI of the obtained organic fluorine resin are shown in Table 1.

[0051] Table 1

[0052] Group 1 2 3 4 5 Organic fluorine monomers 30 40 50 20 60 DMF 150 160 180 120 200 BPO 0.3 0.3 0.5 0.5 0.5 Synthetic organic fluorine resin code A1 A2 A3 A4 A5 Molecular weight of organic fluorine resin 12W 14W 17W 9W 20W Organic fluorine resin PDI 1.32 1.54 1.73 1.07 2.04

[0053] Example 2

[0054] This embodiment relates to a Mini LED chip packaging method, comprising the following steps:

[0055] (1) Cleaning the Mini LED chip substrate;

[0056] (2) A hydrophobic coating composition is spot-coated on the substrate around the periphery of each Mini LED chip to a thickness of 30 μm, and is heat-baked at 100°C for 60 min to pre-treat a hydrophobic coating. A gap of 500-1000 μm is set between the side of the Mini LED chip and the hydrophobic coating; wherein, the coating composition comprises an organic fluorine resin, a surfactant, and a solvent, the surface tension of the coating composition, and the dryness of the hydrophobic coating surface are shown in Table 2, in parts by mass;

[0057] (3) A layer of two-component (containing hydrogen and vinyl) silicone encapsulation adhesive with a thickness of 230 μm was applied to the pre-treated Mini LED chip substrate and baked and cured at 80°C*60min+150°C*60min. The performance of the chip electrode after encapsulation is shown in Table 2.

[0058] Among them, the surface tension test uses a surface tension tester to test the prepared hydrophobic coating composition and record the corresponding data; the surface dryness test uses a finger wearing a rubber glove to touch the surface of the cured hydrophobic coating to observe whether there are fingerprints. If there are fingerprints, the surface dryness is NG; if there are no fingerprints, the surface dryness is OK; whether the encapsulation surface glue can automatically separate is observed to see whether the encapsulation surface glue can automatically form independent units during the first stage pre-curing process.

[0059] Table 2

[0060]

[0061] It can be seen from Table 1 and Table 2 that, within the scope defined by the present invention, when other components remain unchanged, the larger the molecular weight and PDI of the organic fluororesin, the smaller the surface tension, and the surface can be dried normally, and the cells can be automatically spaced after the surface glue is applied. When the molecular weight of the organic fluororesin exceeds 18W, the PDI exceeds 1.8, the surface tension is small, but the hydrophobic coating cannot be dried after application. When the molecular weight of the organic fluororesin is less than 12W, the PDI is less than 1.2, the surface tension is large, and the cells cannot be automatically spaced after the surface is dried by applying the surface glue. Organic fluororesins with other structures cannot automatically space cells after the surface is dried by applying the surface glue because of their large surface tension.

[0062] Example 3

[0063] This embodiment relates to a Mini LED chip packaging method. The packaging steps are the same as those in Example 2, except that the components and contents of the coating composition are different. The coating composition includes an organic fluorine resin, a surfactant, and a solvent, and the surface tension of the coating composition, as well as the dryness of the hydrophobic coating surface and the packaging spacing, as shown in Table 3.

[0064] Table 3

[0065] Group 1 2 3 4 5 Organic fluorine resin A1 5 7 10 20 3 Gemini fatty alcohol polyoxyethylene ether 4 4 4 4 4 n-Butanol 65 65 65 65 65 2-Methyl-1-butanol 25 25 25 25 25 Surface tension mN / m 14.86 13.36 11.06 8.96 25.73 Surface dryness yes yes yes no yes Can the packaging surface glue be automatically spaced? yes yes yes N / A no

[0066] As shown in Table 3, within the scope of the present invention, when other components remain unchanged, the greater the amount of organic fluorine resin added, the smaller the surface tension, the surface can be dried normally, and the cells can be automatically spaced after the encapsulation surface glue is applied. When the amount of organic fluorine resin added is greater than 10 parts, the surface tension is small, but the hydrophobic coating cannot be dried after application. When the amount of organic fluorine resin added is less than 5 parts, the surface tension is large, and the surface glue cannot automatically space the cells after drying.

[0067] Comparative Example 1

[0068] This comparative example relates to a Mini LED chip packaging method. The difference from Group 1 of Example 2 is that no hydrophobic coating pretreatment is performed, and the chip is directly packaged using a packaging adhesive. The method specifically includes the following steps:

[0069] (1) Cleaning the Mini LED chip substrate;

[0070] (2) A layer of two-component (containing hydrogen and vinyl) silicone encapsulation adhesive is directly coated on the Mini LED chip substrate with a thickness of 230 μm and baked and cured at 80°C*60min+150°C*60min.

[0071] Individual chips were removed from the encapsulated substrates of Group 1 of Example 2 and Comparative Example 1, and then the same process was used to fill the surface adhesive for encapsulation. In Group 1 of Example 2, because the encapsulation surface adhesive after filling was separated by the hydrophobic coating, there was a certain gap between it and the original encapsulation surface adhesive on the adjacent chip, so that no obvious difference could be seen after the display was lit. However, in Comparative Example 1, because the encapsulation surface adhesive of the chip was a whole, when the individual chips were removed separately and then filled and encapsulated, there was a color difference between the encapsulation surface adhesive after filling and encapsulation, and there was a clear difference after the display was lit.

[0072] In summary, the present invention pre-coats a hydrophobic coating composition on the substrate around each Mini LED chip to form a hydrophobic coating, and then coats the entire Mini LED chip substrate with a packaging surface glue. The packaging surface glue shrinks during the baking and curing process to achieve individual packaging of the Mini LED chip; when a single Mini LED chip on the packaged Mini LED chip substrate is defective, only this independent unit needs to be removed and repaired without affecting the adjacent units, which greatly reduces the cost of chip repair and improves the service life of the LED display; organic fluorine resin is added to the hydrophobic coating composition to obtain a composition with low surface tension, thereby achieving excellent hydrophobic effect, thereby achieving the shrinkage of the packaging surface glue during the low-temperature baking stage, and the coating composition has high thermal stability and chemical stability.

[0073] The present invention has been described in detail above with reference to specific embodiments and exemplary examples. However, these descriptions should not be construed as limiting the present invention. Those skilled in the art will appreciate that various equivalent substitutions, modifications, or improvements may be made to the technical solutions and implementations of the present invention without departing from the spirit and scope of the present invention, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A Mini LED chip packaging method, characterized in that: The steps include: S1. Apply a hydrophobic coating composition on the substrate around each Mini LED chip and perform a heat-bake pretreatment to form a hydrophobic coating, with a gap set between the side of the Mini LED chip and the hydrophobic coating; Wherein, the hydrophobic coating composition comprises, by mass, 5-10 parts of an organic fluorine resin, 0.05-10 parts of a surfactant, and 80-95 parts of a solvent; S2. Apply a layer of packaging surface glue on the pre-treated Mini LED chip substrate and bake and cure it. The packaging surface glue shrinks into an independent packaging unit with the Mini LED chip as the center to achieve independent packaging of the Mini LED chip.

2. The Mini LED chip packaging method according to claim 1, wherein: In S1, the general structural formula of the organic fluorine resin is: Wherein, n is an integer greater than 0; R1 and R2 are independently selected from one or more of hydrogen, benzene ring, C1-C4 alkyl, C1-C4 fatty acid, and C1-C3 fatty alcohol.

3. The Mini LED chip packaging method according to claim 2, wherein: The organic fluorine resin has a molecular weight of 10w-18w and a PDI of 1.2-1.

8.

4. The Mini LED chip packaging method according to claim 1, wherein: In S1, the surface tension of the hydrophobic coating composition is 10-15 mN / m.

5. The Mini LED chip packaging method according to claim 1, wherein: In S1, the heat baking temperature is 80-150° C. and the time is 10-60 minutes.

6. The Mini LED chip packaging method according to claim 1, wherein: In S2, the baking and curing is divided into two stages: The first stage of baking is at a temperature of 60-100°C and a time of 30-60 minutes; The second stage baking temperature is 100-150℃ and the time is 60-180min.

7. The Mini LED chip packaging method according to claim 1, wherein: In S1, the dot coating thickness of the hydrophobic coating composition is 10-50 μm; in S2, the coating thickness of the encapsulation surface adhesive is 200-260 μm.

8. The Mini LED chip packaging method according to claim 1, wherein: In S1, the surfactant is Gemini fatty alcohol polyoxyethylene ether.

9. The Mini LED chip packaging method according to claim 1, wherein: In S1, the solvent is selected from one or more of n-butanol, isobutanol, 2-methyl-1-butanol, isopentanol, 2,3-dimethyl-1-butanol, 4-methyl-2-pentanol, isohexanol, isoheptanol, 1-octanol, 1-nonanol and 1-decanol.

10. The Mini LED chip packaging method according to claim 1, wherein: In S2, the packaging surface adhesive is a silicone packaging adhesive or an epoxy resin packaging adhesive.

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