Display screen packaging method based on GOB

Abstract

The invention relates to a display screen packaging method based on GOB, and belongs to the technical field of display screen packaging. Comprising the following steps: uniformly mixing a first modified epoxy resin composition, covering the front surface of an LED module, controlling the covering thickness of the obtained mixture, uniformly mixing raw materials of a second modified epoxy resin composition after primary mould pressing and primary curing, completely covering an LED chip, and performing secondary mould pressing and secondary curing to obtain the GOB-based display screen, the first modified epoxy resin composition comprises matrix epoxy resin, modified epoxy resin, modified spherical graphene, a curing agent and a weather-proof agent; the second modified epoxy resin composition comprises matrix epoxy resin, modified epoxy resin, a curing agent and a weather-proof agent. By improving the GOB packaging process and introducing the modified spherical graphene and the modified epoxy resin, the problems of non-uniform heat dissipation and local display color cast caused by secondary aggregation of graphene in the mold pressing process are solved.

Description

Technical Field

[0001] The present invention belongs to the technical field of display screen packaging, and in particular, relates to a display screen packaging method based on GOB. Background Art

[0002] GOB, the full name of which is GLUEONTHEBOARD, is a special packaging method for LED display screens. Simply put, after fixing the LED lamp beads on the PCB (printed circuit board), a special optical thermal conductive nano-scale glue filling material is used to fill the gaps between the lamp beads to form a tightly connected and highly protected whole. Because the glue filling material tightly fills the gaps between the lamp beads, the connection strength between the lamp beads and the PCB board is greatly enhanced, and the risk of the lamp beads falling off is reduced, so that the GOB display screen packaging technology can achieve comprehensive protection for the LED display screen, including waterproof, moisture-proof, dust-proof, anti-collision, anti-static and other functions. This high protection enables the LED display screen to operate stably in various harsh environments.

[0003] In the existing GOB display screen packaging process, in order to cope with the heat generated by the light-emitting LED lamp beads, thermal conductive fillers are generally added to the potting glue, and thermal conductive graphene is often used, so that the heat generated by the light-emitting LED lamp beads can be released in time to prevent the local overheating of the display screen. However, the addition of this thermal conductive filler leads to the difficulty of the subsequent packaging process. The reasons are: first, the compatibility of thermal conductive graphene with the potting glue is poor. Second, the existing thermal conductive graphene is in the form of lamellar particles with poor sliding properties. It cannot flow with the base glue in the subsequent packaging molding process, causing secondary aggregation of the thermal conductive filler, which not only leads to uneven heat dissipation in the subsequent process, causing uneven heat dissipation problems, but also causes the LED display screen module to produce local display color cast. Therefore, the introduction of thermal conductive fillers must improve the existing GOB display screen packaging process so that after potting, the thermal conductive filler is evenly dispersed in the base glue. Summary of the invention

[0004] The object of the present invention is to provide a display screen packaging method based on GOB.

[0005] The technical problem to be solved by the present invention is that when the thermal conductive filler is introduced, it is impossible to keep it evenly distributed in the base glue during the potting process.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A display screen packaging method based on GOB, comprising:

[0008] After the first modified epoxy resin composition is mixed evenly, it is covered on the front of the LED module, and the coating thickness of the obtained mixture is controlled to ensure that the mixture of the first modified epoxy resin composition penetrates into the entire PCBA. After a first molding and a first curing, the second modified epoxy resin composition raw material completely covers the LED chip, and after a second molding and a second curing, a GOB-based display screen is obtained;

[0009] The first modified epoxy resin composition comprises the following raw materials in parts by weight: 100 parts of base epoxy resin, 25-55 parts of modified epoxy resin, 22-42 parts of modified spherical graphene, 100-200 parts of curing agent, and 1-3 parts of weathering agent;

[0010] The second modified epoxy resin composition comprises the following raw materials in parts by weight: 100 parts of base epoxy resin, 30-60 parts of modified epoxy resin, 100-200 parts of curing agent, and 1-3 parts of weathering agent.

[0011] The present invention improves the GOB packaging process, introduces modified spherical graphene and modified epoxy resin, wherein the original GOB packaging process is improved from a single molding process to a secondary molding process. In the primary molding process, a first modified epoxy resin composition is used, combined with the control of the thickness of spherical graphene and the primary molding process, so that the modified spherical graphene is evenly dispersed in a thin layer of limited thickness during the primary molding process, solving the problems of uneven heat dissipation and local display color cast caused by the secondary aggregation of graphene in the molding process. At the same time, the flame retardant enhancement effect of the modified epoxy resin is utilized to improve the high temperature resistance and flame retardant performance of the heat dissipation uniform layer formed by the primary molding process; finally, the packaging of the entire LED chip is completed by using the second modified epoxy resin composition in the secondary molding process. Since the packaging layer formed by the secondary molding curing does not contact the LED lamp group, there is no problem of heat dissipation due to the heat of the LED lamp, so the modified spherical graphene particles are not introduced to reduce unnecessary production cost expenditure. The conditions of primary molding, primary curing, secondary molding and secondary curing are commonly used process parameters in the technical field, and the present invention does not specifically limit them.

[0012] Furthermore, when the modified epoxy resin composition is mixed, the base epoxy resin and the modified epoxy resin are preheated and then mixed evenly with the remaining material in the first modified epoxy resin composition.

[0013] Furthermore, the preheating temperature of the base epoxy resin and the modified epoxy resin is 50-65° C., and the preheating time is 60-100 min.

[0014] Furthermore, the covering thickness is in the range of one-half to five-sixths of the thickness of the LED chip to ensure that the mixture of the first modified epoxy resin composition penetrates into the entire PCBA and ensures that the heat dissipation uniform layer formed by one-time molding and curing can completely cover the LED lamp group.

[0015] Preferably, the covering thickness is two-thirds of the thickness of the LED chip.

[0016] Furthermore, the modified epoxy resin is prepared by reacting epoxy resin DGEBA, hexamethylene diisocyanate and pentaerythritol methyl silicate.

[0017] Wherein, the molecular structure formula of the pentaerythritol methyl silicate is as follows.

[0018]

[0019] The molecular structural formula of the epoxy resin DGEBA is shown below.

[0020]

[0021] Furthermore, the mass ratio of the epoxy resin DGEBA, hexamethylene diisocyanate and pentaerythritol methyl silicate is 100:20-25:20-25.

[0022] Furthermore, the reaction conditions of the epoxy resin DGEBA and pentaerythritol methyl silicate are: stirring and reacting for 4-8 hours in tetrahydrofuran and an organic tin catalyst at a temperature of 55-75°C.

[0023] In the present invention, a modified epoxy resin is introduced. By introducing heat-resistant side chains, on the one hand, the heat resistance and flame retardancy of the final cured composite are improved. On the other hand, the presence of the side chains promotes the interface performance between the epoxy resin and the modified spherical graphene. By utilizing the steric hindrance effect of the side chains, the modified spherical graphene is further evenly dispersed in the composite formed by the first modified epoxy resin composition.

[0024] Furthermore, the modified spherical graphene is spherical activated graphene powder, which is prepared by a mixed solution of graphene grafted with an aminosilane coupling agent, a surfactant, water and ethanol through a mixed spray drying process, wherein during spray drying, the inlet temperature is 150-170°C and the outlet temperature is 60-80°C.

[0025] Furthermore, when the graphene grafted with the aminosilane coupling agent, a surfactant, a mixed solution of water and ethanol are mixed, the mass concentration of the graphene grafted with the aminosilane coupling agent is 1-3 mg / mL, the amount of the surfactant accounts for 0.1-3% of the mass of the mixed solution of water and ethanol, and the volume ratio of water to ethanol in the mixed solution of water and ethanol is 8-10:0-2.

[0026] Furthermore, the step of obtaining the graphene grafted with the aminosilane coupling agent comprises:

[0027] The aminosilane coupling agent and graphene oxide are heated to 50-60° C. in the presence of ethanol and water, and stirred for reaction for 4-12 hours.

[0028] Furthermore, the mass ratio of the graphene oxide to the aminosilane coupling agent is 10:1-2.5.

[0029] Furthermore, the curing agent is one or any combination of phthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, and methylphthalic anhydride.

[0030] Furthermore, the base epoxy resin is one of bisphenol A type epoxy resins.

[0031] Preferably, the matrix epoxy resin is epoxy resin DGEBA.

[0032] Beneficial effects of the present invention:

[0033] The present invention discloses a display screen packaging method based on GOB. By improving the GOB packaging process and introducing modified spherical graphene and modified epoxy resin, the present invention not only solves the problems of uneven heat dissipation and local display color cast caused by secondary aggregation of graphene formed during the molding process, but also improves the heat resistance and flame retardancy of the composite obtained by encapsulation and curing, and further improves the safety of the LED chip obtained by encapsulation. DETAILED DESCRIPTION

[0034] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] Example 1

[0036] Preparation of modified spherical graphene:

[0037] A1. Ultrasonic disperse 100 g of graphene oxide in a mixed solution of 20 mL of water and 180 mL of ethanol, then add 10 g of aminosilane coupling agent (KH-550) at 50 ° C with stirring, and stir to react for 12 h, age, separate, take the precipitate, wash with water, wash with ethanol, and dry to obtain graphene grafted with aminosilane coupling agent.

[0038] A2. Ultrasonic dispersion of graphene grafted with an aminosilane coupling agent in a mixed solution of a surfactant, water and ethanol, followed by spray drying to obtain modified spherical graphene, wherein the mass concentration of the graphene grafted with the aminosilane coupling agent is 1 mg / mL, the amount of the surfactant used accounts for 0.1% of the mass of the mixed solution of water and ethanol, the volume ratio of water to ethanol in the mixed solution of water and ethanol is 8:2, and during spray drying, the inlet temperature is 160° C. and the outlet temperature is 70° C.

[0039] Example 2

[0040] Preparation of modified spherical graphene:

[0041] A1. Ultrasonic disperse 100 g of graphene oxide in a mixed solution of 20 mL of water and 180 mL of ethanol, then add 25 g of aminosilane coupling agent (KH-550) at 60 ° C with stirring, and stir to react for 4 hours, age, separate, take the precipitate, wash with water, wash with ethanol, and dry to obtain graphene grafted with aminosilane coupling agent.

[0042] A2. Ultrasonic dispersion of graphene grafted with an aminosilane coupling agent in a mixed solution of a surfactant, water and ethanol, followed by spray drying to obtain modified spherical graphene, wherein the mass concentration of the graphene grafted with the aminosilane coupling agent is 3 mg / mL, the amount of the surfactant used accounts for 3% of the mass of the mixed solution of water and ethanol, the volume ratio of water to ethanol in the mixed solution of water and ethanol is 10:0, and during spray drying, the inlet temperature is 170° C. and the outlet temperature is 80° C.

[0043] Example 3

[0044] Preparation of modified epoxy resin:

[0045] After 20 g of hexamethylene diisocyanate, 20 g of pentaerythritol methyl silicate, 5 g of dibutyltin dilaurate and 150 mL of tetrahydrofuran were mixed evenly, the mixture was heated to 55 °C and stirred for reaction for 2 h, and then 100 g of epoxy resin DGEBA was added, the reaction was continued with stirring for 4 h, the reaction was stopped, and the mixture was rotary evaporated to obtain a modified epoxy resin.

[0046] Example 4

[0047] Preparation of modified epoxy resin:

[0048] After 25 g of hexamethylene diisocyanate, 25 g of pentaerythritol methyl silicate, 5 g of dibutyltin dilaurate and 150 mL of tetrahydrofuran were mixed evenly, heated to 75 ° C and stirred for reaction for 1 hour, then 100 g of epoxy resin DGEBA was added, and the stirring reaction was continued for 7 hours. The reaction was stopped and rotary evaporated to obtain a modified epoxy resin.

[0049] Example 5

[0050] The display screen packaging method based on GOB includes:

[0051] The first step is to prepare materials: prepare the following raw materials in parts by weight: 100 parts of base epoxy resin (epoxy resin DGEBA), 25 parts of modified epoxy resin prepared in Example 3, 22 parts of modified spherical graphene prepared in Example 1, 110 parts of curing agent (phthalic anhydride), and 1 part of weathering agent (weathering agent 3035), that is, prepare the raw materials for the first modified epoxy resin composition; prepare the following raw materials in parts by weight: 100 parts of base epoxy resin (epoxy resin DGEBA), 30 parts of modified epoxy resin prepared in Example 3, 110 parts of curing agent (phthalic anhydride), and 1 part of weathering agent (weathering agent 3035), that is, prepare the raw materials for the second modified epoxy resin composition;

[0052] The second step is packaging: preheat the base epoxy resin and modified epoxy resin in the first modified epoxy resin composition at 50°C for 100 minutes, mix them evenly with the remaining material in the first modified epoxy resin composition, and then cover the front of the LED module. Control the coverage thickness of the obtained mixture (the coverage thickness is two-thirds of the thickness of the LED chip) to ensure that the mixture of the first modified epoxy resin composition penetrates into the entire PCBA. After one molding and one curing, the second modified epoxy resin composition raw material completely covers the LED chip. After secondary molding and secondary curing, a GOB-based display screen is obtained.

[0053] Example 6

[0054] The display screen packaging method based on GOB includes:

[0055] The first step is to prepare materials: prepare the following raw materials in parts by weight: 100 parts of matrix epoxy resin (epoxy resin DGEBA), 35 parts of modified epoxy resin prepared in Example 3, 32 parts of modified spherical graphene prepared in Example 1, 150 parts of curing agent (phthalic anhydride), and 2 parts of weathering agent (weathering agent 3035), that is, prepare the raw materials for the first modified epoxy resin composition; prepare the following raw materials in parts by weight: 100 parts of matrix epoxy resin (epoxy resin DGEBA), 40 parts of modified epoxy resin prepared in Example 3, 150 parts of curing agent (phthalic anhydride), and 2 parts of weathering agent (weathering agent 3035), that is, prepare the raw materials for the second modified epoxy resin composition;

[0056] The second step is packaging: preheat the base epoxy resin and modified epoxy resin in the first modified epoxy resin composition at 55°C for 80 minutes, mix them evenly with the remaining material in the first modified epoxy resin composition, and then cover the front of the LED module. Control the coverage thickness of the obtained mixture (the coverage thickness is two-thirds of the thickness of the LED chip) to ensure that the mixture of the first modified epoxy resin composition penetrates into the entire PCBA. After one molding and one curing, the second modified epoxy resin composition raw material completely covers the LED chip. After secondary molding and secondary curing, a GOB-based display screen is obtained.

[0057] Example 7

[0058] The display screen packaging method based on GOB includes:

[0059] The first step is to prepare materials: prepare the following raw materials in parts by weight: 100 parts of matrix epoxy resin (epoxy resin DGEBA), 55 parts of modified epoxy resin prepared in Example 4, 42 parts of modified spherical graphene prepared in Example 2, 200 parts of curing agent (phthalic anhydride), and 3 parts of weathering agent (weathering agent 3035), that is, prepare the raw materials for the first modified epoxy resin composition; prepare the following raw materials in parts by weight: 100 parts of matrix epoxy resin (epoxy resin DGEBA), 60 parts of modified epoxy resin prepared in Example 4, 200 parts of curing agent (phthalic anhydride), and 3 parts of weathering agent (weathering agent 3035), that is, prepare the raw materials for the second modified epoxy resin composition;

[0060] The second step is packaging: preheat the base epoxy resin and modified epoxy resin in the first modified epoxy resin composition at 65°C for 60 minutes, mix them evenly with the remaining material in the first modified epoxy resin composition, and then cover the front of the LED module. Control the coverage thickness of the obtained mixture (the coverage thickness is two-thirds of the thickness of the LED chip) to ensure that the mixture of the first modified epoxy resin composition penetrates into the entire PCBA. After one molding and one curing, the second modified epoxy resin composition raw material completely covers the LED chip. After secondary molding and secondary curing, a GOB-based display screen is obtained.

[0061] Comparative Example 1

[0062] The display screen packaging method based on GOB includes:

[0063] Step 1, preparing materials: compared with the first modified epoxy resin composition in Example 5, an equal amount of the modified spherical graphene prepared in Example 1 is replaced with the graphene grafted with an aminosilane coupling agent prepared in Example 1, and the raw materials of the second modified epoxy resin composition are the same as those in Example 5;

[0064] Step 2: Packaging: Same as in Example 5.

[0065] Comparative Example 2

[0066] The display screen packaging method based on GOB includes:

[0067] The first step, preparing materials: compared with the first modified epoxy resin composition in Example 5, an equal amount of the modified epoxy resin in the raw material is replaced with epoxy resin DGEBA, and the rest is the same; compared with the second modified epoxy resin composition in Example 5, an equal amount of the modified epoxy resin in the raw material is replaced with epoxy resin DGEBA, and the rest is the same;

[0068] Step 2: Packaging: Same as in Example 5.

[0069] Comparative Example 3

[0070] The display screen packaging method based on GOB includes:

[0071] The first step, material preparation: the same as in Example 5;

[0072] The second step is packaging: preheat the base epoxy resin and modified epoxy resin in the first modified epoxy resin composition at 50°C for 100 minutes, mix them evenly with the remaining material in the first modified epoxy resin composition, and then cover the front of the LED module. Control the coverage thickness of the obtained mixture (the coverage thickness is one-third of the thickness of the LED chip) to ensure that the mixture of the first modified epoxy resin composition penetrates into the entire PCBA. After one molding and one curing, the second modified epoxy resin composition raw material completely covers the LED chip. After secondary molding and secondary curing, a GOB-based display screen is obtained.

[0073] The color difference value ΔE of the display screens of Examples 5-7 and Comparative Examples 1-3 was tested, and the results are shown in Table 1, wherein ΔE≤1.5: the color accuracy is excellent and can be positioned as S grade; ΔE is between 1.5-3: the color accuracy is very good and is positioned as A grade; ΔE is between 3-5: the color accuracy is excellent and is positioned as B grade; ΔE is between 5-8: the color accuracy is ordinary and is positioned as C grade; ΔE>8: the color accuracy is very poor and most people can see the color difference.

[0074] Examples 5-7 and comparative examples 1-3 were cut (using CNC Cutting Machine modular cutting) and physical property tests were performed. The results are shown in Table 1.

[0075] Whether there is color cast

[0076] Heat aging resistance: After baking at 90℃ for 3 days,

[0077] Table 1

[0078]

[0079]

[0080] It can be seen from the data in Table 1 that the display screens obtained by encapsulation in Examples 5-7 have no deviation and have good heat dissipation and flame retardant properties.

[0081] In the description of the specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0082] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the invention or exceed the scope defined by the claims, they shall all fall within the protection scope of the present invention.

Claims

1. A display screen packaging method based on GOB, characterized in that: include: After the first modified epoxy resin composition is mixed evenly, it is covered on the front of the LED module, and the coating thickness of the obtained mixture is controlled. After a first molding and a first curing, the second modified epoxy resin composition raw material is mixed evenly, and the LED chip is completely covered. After a second molding and a second curing, a GOB-based display screen is obtained; The first modified epoxy resin composition comprises the following raw materials in parts by weight: 100 parts of base epoxy resin, 25-55 parts of modified epoxy resin, 22-42 parts of modified spherical graphene, 100-200 parts of curing agent, and 1-3 parts of weathering agent; The second modified epoxy resin composition comprises the following raw materials in parts by weight: 100 parts of base epoxy resin, 30-60 parts of modified epoxy resin, 100-200 parts of curing agent, and 1-3 parts of weathering agent.

2. A display screen packaging method based on GOB according to claim 1, characterized in that: When the first modified epoxy resin composition is mixed, the base epoxy resin and the modified epoxy resin are preheated and then mixed evenly with the remaining material in the first modified epoxy resin composition.

3. A display screen packaging method based on GOB according to claim 1, characterized in that: The covering thickness is in the range of one-half to five-sixths of the thickness of the LED chip.

4. A display screen packaging method based on GOB according to claim 1, characterized in that: The modified epoxy resin is prepared by reacting epoxy resin DGEBA, hexamethylene diisocyanate and pentaerythritol methyl silicate.

5. A display screen packaging method based on GOB according to claim 4, characterized in that: The mass ratio of the epoxy resin DGEBA, hexamethylene diisocyanate and pentaerythritol methyl silicate is 100:20-25:20-25.

6. A display screen packaging method based on GOB according to claim 4, characterized in that: The reaction conditions of the epoxy resin DGEBA and pentaerythritol methyl silicate are as follows: stirring and reacting for 4-8 hours in tetrahydrofuran and an organic tin catalyst at a temperature of 55-75°C.

7. A display screen packaging method based on GOB according to claim 1, characterized in that: The modified spherical graphene is spherical activated graphene powder, which is prepared by a mixed solution of graphene grafted with an aminosilane coupling agent, a surfactant, water and ethanol through a mixed spray drying process.

8. A display screen packaging method based on GOB according to claim 7, characterized in that: When the graphene grafted with the aminosilane coupling agent, a surfactant, and a mixed solution of water and ethanol are mixed, the mass concentration of the graphene grafted with the aminosilane coupling agent is 1-3 mg / mL, the amount of the surfactant used accounts for 0.1-3% of the mass of the mixed solution of water and ethanol, and the volume ratio of water to ethanol in the mixed solution of water and ethanol is 8-10:0-2.

9. A display screen packaging method based on GOB according to claim 7, characterized in that: The step of obtaining the graphene grafted with the aminosilane coupling agent comprises: The aminosilane coupling agent and graphene oxide are heated to 50-60° C. in the presence of ethanol and water, and stirred for reaction for 4-12 hours.

10. A display screen packaging method based on GOB according to claim 1, characterized in that: The curing agent is one or any combination of phthalic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride and methylphthalic anhydride.

Images