An epoxy plastic packaging material for optical coupling products and a preparation method thereof

Abstract

The present application relates to the technical field of epoxy resin, and especially relates to an epoxy plastic encapsulation material for optical coupling product packaging and a preparation method thereof, and preparation raw materials comprise: an epoxy resin, a curing agent, a catalyst, a ratio of a hydroxyl equivalent weight in the curing agent to an epoxy equivalent weight in the epoxy resin is 0.5-1.5.The present application obtains a self-flame-retardant environmental protection optical coupling EMC with high reflectivity, good heat resistance, good workability and high reliability by optimizing the types and collocations of resins, the types and contents of flame retardants, the types and contents of catalysts, the types and contents of dyeing agents, the types and contents of release agents and the types and contents of silane coupling agents, and the environmental protection preparation raw materials not only complete the replacement of all non-environmental protection raw materials, but also ensure the flame retardation, flowability, workability, reflectivity, heat resistance and reliability of EMC.

Description

Technical Field

[0001] This invention relates to the field of epoxy resin technology, and in particular to an epoxy molding compound for encapsulating optocoupler products and its preparation method. Background Technology

[0002] An optocoupler is a device that integrates a light-emitting diode (LED) and a photodetector into a single package. Unlike other optical devices, the light from an optocoupler does not escape outside the package, and its appearance is similar to that of a non-isolated / solid-state relay. This places high demands on the package's EMC (electromagnetic compatibility) reflectivity in the near-infrared band.

[0003] Currently, most optocoupler EMC materials are not environmentally friendly, which greatly limits their application. To transform EMC from environmentally friendly to environmentally friendly, many problems need to be solved. Environmentally friendly raw materials cannot simultaneously meet all performance requirements; further formulation optimization is needed to ensure EMC achieves a balance of various properties. For example, considering cost and flame retardancy, environmentally friendly resins and metal hydroxide flame retardants are unlikely to achieve a V0 flame retardancy rating. Secondly, while achieving environmental friendliness and self-flame retardancy, it is necessary to ensure high reflectivity and heat resistance (high reliability at reflow temperatures) of the EMC. Finally, titanium dioxide and metal hydroxide flame retardants can have a significant negative impact on the workability and reliability of the EMC. Therefore, ensuring workability such as viscosity and flowability, as well as reliability properties such as adhesion and MSL, while maintaining environmental friendliness is extremely difficult.

[0004] Chinese patent CN114456543A discloses an epoxy resin composition, epoxy resin molding compound, its preparation method, and its application. The epoxy resin composition contains: 2-11 wt% epoxy resin, 1-6 wt% curing agent, 85-93 wt% solid filler, 0.1-1 wt% ion trapping agent, 0.1-1 wt% low-stress modifier, 0.1-1 wt% coupling agent, 0.1-1 wt% accelerator, 0.1-1 wt% release agent, 1-10 wt% flame retardant, and 0.1-1 wt% colorant. It has a high glass transition temperature, reaching above 160°C, and a low coefficient of linear expansion, exhibiting excellent warpage performance. However, it still cannot meet environmental protection requirements and cannot achieve a balance between environmental protection and performance. Summary of the Invention

[0005] The first aspect of the present invention provides an epoxy molding compound for packaging optocoupler products, the raw materials for which include: epoxy resin, curing agent, and catalyst.

[0006] To simultaneously ensure crosslinking density and reflectivity, the ratio of hydroxyl equivalent in the curing agent to epoxy equivalent in the epoxy resin is 0.5-1.5.

[0007] In some embodiments, the epoxy resin includes at least one of o-cresol type epoxy resin, bisphenol A type epoxy resin, and phenol type epoxy resin, and / or the epoxy equivalent of the epoxy resin is 170-300 g / eq, and the softening point is 60-80 °C.

[0008] During the research and development, the applicant discovered that epoxy resin with a specific epoxy equivalent can significantly improve the high reflectivity and heat resistance of the system without adding non-environmentally friendly solvents and halogens or other potent substances. It is speculated that the reason may be that the epoxy resin under this parameter can be better compatible with the fillers, flame retardants and other components in the system, so as to improve the overall performance of the molding compound.

[0009] In some embodiments, the curing agent has a hydroxyl equivalent of 90-180 g / eq, a softening point of 70-90°C, and / or the curing agent includes at least one of linear phenolic resin, XYLOK phenolic resin, biphenyl resin, and acid anhydride.

[0010] To improve the heat resistance and curing performance of the molding compound, in some embodiments, the catalyst includes at least one of phosphorus-based catalysts, imidazole catalysts, and amine catalysts, and / or the content of the catalyst accounts for 0.5-5 wt% of the total amount of the epoxy resin and curing agent. Preferred manufacturers of the catalyst include Shikoku Chemical, Nippon Chemical Industries, Ltd., and domestically developed catalysts.

[0011] In some embodiments, the raw materials for preparation also include: dyes, release agents, flame retardants, fillers, and silane coupling agents.

[0012] In some embodiments, the particle size of the dye is 0.1-1 μm, and / or the content of the dye accounts for 80-200 wt% of the total amount of the epoxy resin and curing agent.

[0013] To improve the reflectivity and heat resistance of the molding compound, the dye is preferably titanium dioxide, preferably from any one or more of the following sources: Denki Chemical, Ishihara Sangyo, and DuPont Ti-Pure.

[0014] In order to allow the release agent to precipitate onto the mold surface during curing and to prevent oxidation over a long period of time, in some embodiments, the release agent includes at least one of oxidized polyethylene wax, palm wax, polyolefin wax, rice bran wax, carnauba wax, and Montan wax, and / or the content of the release agent accounts for 2-8 wt% of the total amount of the epoxy resin and curing agent.

[0015] In some embodiments, the flame retardant includes at least one of metal hydroxides and phosphorus-based flame retardants, and / or the content of the flame retardant accounts for 80-200 wt% of the total amount of the epoxy resin and curing agent.

[0016] In some embodiments, the filler includes at least one of silica fume, molecular sieve, ceramic powder, and kaolin, and / or the content of the filler accounts for 300-500 wt% of the total amount of epoxy resin and curing agent.

[0017] Furthermore, the filler is silicon powder, preferably with a particle size of 500 nm-5 μm. Preferred manufacturers include Longsen, Electric Chemical, and Lianrui.

[0018] This invention selects to add titanium dioxide to improve whiteness and further enhance reflectivity, and simultaneously adds metal hydroxide as a flame retardant. However, the simultaneous addition of these two substances results in poor EMC flowability, and sticking to the mold occurs after 5-10 continuous molding cycles. When the addition amount is small, the required whiteness and flame retardant effect are not achieved, and interactions further degrade the performance of EMC. To ensure resin wetting of the frame and maintain ultra-low viscosity and flow length >40 for EMC, the applicant unexpectedly discovered that a combination of spherical and angular silica powder can significantly improve the continuous molding capability of the molding compound. Testing showed it to be a fast-curing compound with a gel time of 20-30 seconds and a hot hardness of over 80 at 160℃ for 90 seconds.

[0019] A second aspect of the present invention provides a method for preparing an epoxy molding compound for packaging optocoupler products, the method comprising: mixing raw materials and then co-extruding them to obtain the product.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. This invention, through the optimization of resin types and combinations, flame retardant types and contents, catalyst types and contents, dye types and contents, release agent types and contents, and silane coupling agent types and contents, combined with appropriate processes, yields a self-flame-retardant environmentally friendly optocoupler EMC with high reflectivity, good heat resistance, good workability, and high reliability. The raw materials used in its preparation are environmentally friendly, not only replacing all non-environmentally friendly raw materials but also ensuring the flame retardancy, flowability, workability, reflectivity, heat resistance, and reliability of the EMC.

[0022] 2. In order to ensure the reflectivity of the optocoupler EMC and its high reliability at the Reflow temperature, this invention unexpectedly discovered that selecting titanium oxide with an average particle size of 0.3 μm as a dye and combining it with other high whiteness fillers to form a reflective agent makes the reflectivity of the EMC in the near-infrared band (800nm~1000nm) ≥95%, which is far higher than the existing technology.

[0023] 3. An unexpected discovery of this invention is that when the ratio of the hydroxyl equivalent in the curing agent to the epoxy equivalent in the epoxy resin is 0.5-1.5, both crosslinking density and reflectivity are guaranteed. The prepared molding compound has good reflectivity after extensive testing.

[0024] 4. The present invention preferably uses imidazole catalysts as catalysts, which can significantly improve the curing performance of molding compounds. The prepared molding compounds have good curing performance and suitable gel time after extensive testing.

[0025] 5. The raw material cost of this invention is low, the preparation process is simple, the non-environmentally friendly waste emission pressure during the production process is small, it is environmentally friendly, and has good application prospects. Detailed Implementation

[0026] Examples and Comparative Examples

[0027] Examples 1-12 and Comparative Examples 1-6 all provide an epoxy molding compound for packaging optocoupler products. The raw materials are shown in Table 1-2 by weight. The preparation method is as follows: the raw materials are mixed and then co-extruded to obtain the product.

[0028] The parameters and manufacturers of the raw materials used in the preparation are the same as those in the invention.

[0029] Table 1

[0030]

[0031] Table 2

[0032]

[0033] Performance testing

[0034] The epoxy molding compounds prepared in the examples and comparative examples were made into cylindrical solids and subjected to the following tests. The results are shown in Tables 3-4.

[0035] 1. Viscosity: GB / T 22314-2008;

[0036] 2. Spiral flow length: Refer to ASTM D3123-09;

[0037] 3. Gel time: GBT 33315-2016;

[0038] 4. Hot hardness: GB / T 2567-2021;

[0039] 5. Adhesive strength to the frame: lap joint test, refer to GB / T 13936-2014;

[0040] 6. 800nm ​​Reflectance: Tested using a spectrophotometer. An L value greater than or equal to 95 and an 800nm ​​reflectance greater than or equal to 95% are considered "qualified"; otherwise, they are considered "unqualified".

[0041] 7. Curing performance: GB / T 2567-2021;

[0042] 8. Flame retardancy: UL94-2012Rev.12-2021;

[0043] 9. Moldability: If the appearance after molding is flat and without defects, bubbles, stringing, sticking, warping, and easy to demold, it is recorded as "qualified". If the appearance after molding is uneven or defective, has bubbles, stringing, sticking, warping, or is not easy to demold, it is recorded as "unqualified".

[0044] 10. Heat resistance: Color change of the sample after PMC and Reflow. If it turns yellow, it is marked as "unacceptable".

[0045] 11. Continuous molding modulus: Conduct multiple moldability tests continuously, with standards such as moldability.

[0046] Table 3

[0047] Viscosity / Pa·S @175℃ Spiral flow length / inch@175℃×100s Gel time / s @ 175℃ Hot hardness (Shore D) @160℃×90s Adhesion force to the frame / MPa @175℃×100s 800nm ​​reflectivity Example 1 74 35 12 85 8 97% Example 2 83 38 12 82 6 96% Example 3 85 30 11 83 5 95% Example 4 91 60 30 82 4 95% Example 5 77 40 18 85 10 94% Example 6 84 36 21 82 5 93% Example 7 101 39 13 81 6 93% Example 8 97 40 20 83 6 92% Example 9 62 40 13 85 8 97% Example 10 88 38 16 82 4 95% Example 11 67 45 15 83 6 95% Example 12 79 30 11 84 6 96% Comparative Example 1 80 30 13 85 7 90% Comparative Example 2 145 30 14 77 3 90% Comparative Example 3 134 39 19 67 2 89% Comparative Example 4 65 40 14 84 8 95% Comparative Example 5 83 33 11 85 7 90% Comparative Example 6 144 27 9 83 6 97%

[0048] Table 4

[0049] Curing performance Flame retardant UL94 Modelability Heat resistance Continuous molding modulus Example 1 Good V0 Good Good 100-300 Example 2 Good V0 Good Good 100-300 Example 3 Good V0 Good Good 100-300 Example 4 Good V0 Good Good 100-300 Example 5 Good V0 NG Good 100-300 Example 6 Good V0 Good Good 100-300 Example 7 Good V0 Good Good 100-300 Example 8 Good V0 Good Good 100-300 Example 9 Good V0 Good Good 100-300 Example 10 Good V0 Good Good 100-300 Example 11 Good V0 Good Good 100-300 Example 12 Good V0 Good Good 100-300 Comparative Example 1 NG V0 NG Good 50-100 Comparative Example 2 NG V0 NG Good 5-10 Comparative Example 3 NG V0 NG NG 10-30 Comparative Example 4 Good V0 Good Good 100-300 Comparative Example 5 Good V0 Good NG 100-200 Comparative Example 6 NG V0 NG Good 50-100

[0050] Based on a comprehensive analysis of the above test data, Comparative Example 1 used N,N-dimethylbenzylamine to replace the imidazole catalyst. The results showed that the curing ability and molding properties of EMC decreased after the catalyst replacement, and the reflectivity also decreased to some extent. Comparative Example 2 used a phosphorus-based catalyst, which had good heat resistance in the system and could effectively improve the reflectivity of EMC, but the curing ability was low, resulting in a poor overall effect. Comparative Example 3 used bisphenol A epoxy resin, which significantly reduced heat resistance. Comparative Example 4 was an existing non-environmentally friendly white photocoupler EMC. In comparison, it was found that the composition in the embodiments of the present invention not only completed the transformation of the raw materials from non-environmentally friendly to environmentally friendly, but also achieved performance comparable to or even better than that of non-environmentally friendly EMC. The difference between Example 1 and Comparative Example 5 was only the average particle size of titanium dioxide. The titanium dioxide used in Example 1 had an average particle size of 0.3 μm, while that in Comparative Example 5 was 1-2 μm. The test results showed that Comparative Example 5 had poor reflectivity and heat resistance, and slight discoloration occurred at the reflow temperature. Insufficient whiteness of the aluminum hydroxide used could also lead to this problem. In Comparative Example 6, a large amount of titanium dioxide and aluminum hydroxide were used, which improved heat resistance and reflectivity, but greatly reduced curing ability and moldability.

Claims

1. An epoxy molding compound for optocoupler product packaging, characterized in that, The preparation raw materials include: 75 parts of epoxy resin, 25 parts of curing agent, 3 parts of catalyst, 100 parts of flame retardant, 200 parts of filler, 1 part of coupling agent, 100 parts of dyeing agent, 10 parts of release agent; The epoxy resin is o-cresol type epoxy resin with an epoxy equivalent of 200 g / eq; The curing agent is linear phenol-formaldehyde resin with a hydroxyl equivalent of 106 g / eq; The catalyst is heptadecane imidazole; The flame retardant is aluminum hydroxide with a particle size of 1-10 μm; The filler is silicon powder with a particle size of 0.5-5 μm; The coupling agent is amino silane coupling agent; The dyeing agent is titanium white powder with a particle size of 0.1-1 μm; The release agent is oxidized polyethylene wax.

2. A method for preparing the epoxy molding compound for packaging optocoupler products as described in claim 1, characterized in that, The preparation method comprises: uniformly mixing the preparation raw materials and then co-extruding, to obtain the product.

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