Epoxy molding compound and preparation method and application thereof

Abstract

The invention relates to the technical field of packaging materials, in particular to an epoxy molding compound and a preparation method and application thereof. The epoxy molding compound is prepared from the following raw materials: 40-80 parts of epoxy resin, 1-10 parts of a release agent, 0.1-3 parts of a catalyst, 50-500 parts of filler, 0.1-5 parts of a silane coupling agent and 20-60 parts of a curing agent, the release agent at least comprises alkyd ester wax; the silane coupling agent comprises a methoxy silane coupling agent. According to the invention, the formula component selection and synergistic effect of the epoxy resin molding compound are explored, a specific alkyd wax release agent and a specific methoxy silane coupling agent are preferably added into a resin / curing agent system, the preparation process is optimized, and a preparation mode of low-friction mixing and then extrusion is adopted; the microstructure and interface characteristics of the material are optimized, the novel epoxy molding compound with high CTR, low shrinkage and excellent release property is obtained, and the use requirements of optocoupler product packaging can be well met.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of packaging materials, in particular to an epoxy plastic packaging material and a preparation method and application thereof. BACKGROUND

[0002] Opto-coupler (opto-coupler for short) is a kind of device integrating light emitting diode (LED) and photoelectric detector in a packaging element, which can effectively isolate input circuit and output circuit in electricity, cut off direct electrical connection between them. This isolation characteristic can prevent electrical interference, noise and high voltage, large current and the like of input end from affecting output end, at the same time, it can also avoid the reverse influence of output end failure to input end, greatly improving the stability and reliability of circuit. Current transfer ratio (Current Transfer Ratio, CTR) is a core performance index of opto-coupler device, defined as the ratio of output end photosensitive device (such as photosensitive triode, photosensitive IC) current IC and input end light emitting diode (LED) drive current IF, that is: CTR=IC / IF×100%.

[0003] CTR directly reflects the electro-optical-electric conversion efficiency of optical coupling, which directly affects the following performances: 1) signal transmission reliability, high CTR (>150%) can reduce signal distortion rate, suitable for high-speed communication (such as CAN bus, USB isolation); 2) power consumption control, CTR improvement can reduce the demand for LED driving current, reduce the overall power consumption of the system (such as photovoltaic inverter, electric vehicle BMS); 3) life and stability, low CTR device needs to increase LED current compensation, accelerate LED light decay (CTR attenuation >30% after aging 1000 hours). The CTR of existing optocouplers is generally limited by the following factors: (1) optical loss of packaging material, on the one hand, interface scattering, interface defects such as residual release agent and microcracks cause light scattering, 450nm band transmittance loss >15%; on the other hand, there is material absorption, traditional epoxy resin has intrinsic absorption in near ultraviolet-visible light band, which will reduce the effective light flux; (2) device offset caused by thermal mechanical stress, on the one hand, there is a mismatch in the coefficient of thermal expansion (CTE), the CTE difference between the epoxy plastic packaging material and the LED chip causes thermal stress, leading to alignment offset (offset >5μm) between the LED and the photosensitive device, and the coupling efficiency decreases by >20%; on the other hand, there is a curing shrinkage stress, the curing shrinkage rate of phenolic resin is as high as 0.8-1.0%, and microcracks are formed at the interface after molding; (3) chemical pollution and interface degradation, on the one hand, traditional acid release agent decomposes to generate carboxylic acid (such as stearic acid) at high temperature molding (>170℃), which reacts with epoxy resin to generate light-absorbing salts; on the other hand, there is moisture penetration, interface defects cause moisture intrusion (water absorption >0.8% at 85℃ / 85% RH), leading to ion migration (Na⁺, Cl⁻ concentration >10ppm), and CTR accelerated attenuation (attenuation >25% after aging 500 hours).

[0004] Chinese invention patent CN107446316B discloses an epoxy plastic packaging material composition, an epoxy plastic packaging material and a preparation method thereof, by using isocyanate modified polyether silicone as a stress absorber in the epoxy plastic packaging material, the problem of increasing bending modulus and reducing glass transition temperature when increasing the amount of filler in the existing material is solved, the effects of high glass transition temperature and low bending modulus are realized, and the heat resistance and toughness of the material are improved. Chinese invention patent application CN107868411A discloses an epoxy plastic packaging material for surface mount package, by using multi-aromatic epoxy resin, silicone powder and composite coupling agent and other components in the epoxy plastic packaging material, the delamination problem caused by high temperature reflow soldering is solved, the high reliability and moisture resistance of the epoxy plastic packaging material are realized, and the JEDEC level 1 grade and UL 94V-0 flame retardant standard are met.

[0005] However, these prior arts do not solve the above technical problems, effectively improve the current conversion ratio of the packaging material, and in such a background, it is urgent to provide a plastic packaging material with high CTR, low shrinkage and excellent release, to meet the use requirements of optical coupling product packaging. SUMMARY

[0006] In order to solve the above problems, the present application explores the selection and synergistic effect of the formula components of the epoxy resin plastic packaging material, preferably adds specific alkyd ester wax release agent and specific methoxysilane coupling agent in the resin / curing agent system, and optimizes the preparation process, adopts low-friction mixing and extrusion preparation method, optimizes the microstructure and interface characteristics of the material, obtains a new type of epoxy plastic packaging material with high CTR, low shrinkage and excellent release, which can well meet the use requirements of optical coupling product packaging.

[0007] The present application provides an epoxy plastic packaging material in the first aspect, according to the weight parts, the preparation raw materials of the epoxy plastic packaging material include: epoxy resin 40-80 parts, release agent 1-10 parts, catalyst 0.1-3 parts, filler 50-500 parts, silane coupling agent 0.1-5 parts, curing agent 20-60 parts.

[0008] The epoxy resin can be listed to include one or more combinations of ortho-cresol aldehyde type epoxy resin, bisphenol A type epoxy resin, phenol type epoxy resin.

[0009] In order to improve the performance of the epoxy resin plastic packaging material, optionally, the epoxy resin includes ortho-cresol aldehyde type epoxy resin and bisphenol A type epoxy resin; the mass ratio of the ortho-cresol aldehyde type epoxy resin and the bisphenol A type epoxy resin is (1.5-5):1. The selected epoxy resin of the present application can improve the strength, heat resistance and chemical stability of the plastic packaging material, and inhibit the shrinkage tendency of the material.

[0010] Optionally, the epoxy equivalent of the ortho-cresol aldehyde type epoxy resin is 100-300 g / eq; further optionally 170-190 g / eq; the ortho-cresol aldehyde type epoxy resin can be commercially available, such as NPPN-638 of Nanya Plastic.

[0011] Optionally, the epoxy equivalent of the bisphenol A type epoxy resin is 150-400 g / eq; further optionally 238-270 g / eq; the bisphenol A type epoxy resin can be commercially available, such as Huntsman GY-250.

[0012] The phenol type epoxy resin can be commercially available, such as Mitsubishi YX-4000H.

[0013] The curing agent can be listed to include one or more combinations of linear phenolic resin, BPA (bisphenol A) phenolic resin, acid anhydride.

[0014] Optionally, the hydroxyl equivalent weight of the linear phenolic resin is 90-200 g / eq; the linear phenolic resin can be commercially available, such as Meicen MEW-180.

[0015] The BPA (bisphenol A) phenolic resin can be commercially available, such as Shengquan SH-2100.

[0016] The acid anhydride can be exemplified by tetrahydrophthalic anhydride (THPA), methyltetrahydrophthalic anhydride (MTHPA), hexahydrophthalic anhydride (HHPA), methylhexahydrophthalic anhydride (MHHPA), phthalic anhydride (PA), trimellitic anhydride (TMA), pyromellitic dianhydride (PMDA), and the like.

[0017] In order to improve the crosslinking density, optionally, the equivalent ratio of active groups in the curing agent to epoxy groups in the epoxy resin is (0.5-1.5): 1; it can be exemplified by 0.5:1, 1:1, 1.2:1, 1.5:1.

[0018] The active group is a group capable of reacting with the epoxy group in the epoxy resin.

[0019] Optionally, the catalyst includes a phosphorus-based catalyst, a modified amine catalyst, or an imidazole catalyst.

[0020] The phosphorus-based catalyst can be exemplified by boron trifluoride triethyl phosphine, boron trifluoride triisopropyl phosphine, trimethyl phosphine, triphenyl phosphine and its derivatives, cyclotriphosphine, and phosphoramine compounds, and the like.

[0021] The imidazole catalyst can be exemplified by 2-methylimidazole (2MZ), 2-ethyl-4-methylimidazole (2E4MZ), 2-phenylimidazole (2PZ), and the like; the imidazole catalyst can be commercially available, such as Shikoku Kasei products.

[0022] The modified amine catalyst can be commercially available, such as Aidelco EH-4360S.

[0023] Optionally, the addition amount of the catalyst is 0.1-3% of the total amount of the epoxy resin and the curing agent (such as phenolic resin); it can be exemplified by 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.5%, 2%, 2.5%, 3%.

[0024] The release agent can be exemplified by a combination of one or more of oxidized polyethylene wax, palm wax, polyolefin wax, alkyd ester wax, carnauba wax, montan wax, and the like.

[0025] The oxidized polyethylene wax can be commercially available, such as Honeywell A-C 316A; the palm wax can be commercially available, such as BASF Luwax OA5; the polyolefin wax can be commercially available, such as Mitsui Chemical Hi-wax 7202P; the alkyd ester wax can be commercially available, such as Clariant Licocene PE 4201.

[0026] Optionally, the release agent at least includes an alkyd ester wax.

[0027] Further optionally, the release agent further includes an oxidized polyethylene wax or an acid wax.

[0028] Optionally, the release agent is added in an amount of 2-8% of the total amount of the epoxy resin and the curing agent (e.g., phenolic resin); which can be listed as 2%, 2.5%, 3%, 4%, 5%, 6%, 7%, 8%.

[0029] The filler can be listed to include silicon powder, calcium carbonate, barium sulfate, etc.

[0030] Optionally, the filler includes silicon powder, and the silicon powder has a median particle size of 10-30 μm.

[0031] Optionally, the filler is added in an amount of 60-80% of the total mass of the epoxy encapsulating material.

[0032] The silane coupling agent can be listed to include a methoxysilane coupling agent, an allylsilane coupling agent, a mercaptosilane coupling agent, etc.

[0033] Optionally, the silane coupling agent includes a methoxysilane coupling agent.

[0034] The methoxysilane coupling agent can be commercially available, such as Dow Chemical Z-6040 (KH560); the allylsilane coupling agent can be commercially available, such as Dow Chemical Z-6310; the mercaptosilane coupling agent can be commercially available, such as Shinkolite Chemical KBM-803.

[0035] Optionally, the silane coupling agent is added in an amount of 0.05-0.15% of the mass of the filler.

[0036] Optionally, the CTR of the epoxy encapsulating material is above 195%; and further optionally above 200%.

[0037] In some embodiments, the total amount of the epoxy resin and the curing agent (e.g., phenolic resin) is 100 parts by weight (PPR).

[0038] The second aspect of the present application provides a preparation method of an epoxy encapsulating material, and the preparation steps of the epoxy encapsulating material include: S1. Pretreatment: The epoxy resin, release agent, catalyst, filler, silane coupling agent, and curing agent are respectively subjected to crushing treatment, and the particle size is crushed to 30 mesh or less; S2. Mixing: The crushed epoxy resin, release agent, catalyst, filler, silane coupling agent, and curing agent are uniformly mixed; S3. Extrusion: The uniformly mixed material is transferred to an extruder, and an extrusion melt is pressed to obtain an epoxy plastic packaging material.

[0039] Optionally, the S2 step is mixed by using a high-speed mixer.

[0040] In some embodiments, in order to meet the high light transmittance requirement of optical coupling EMC, the paddle and inner wall of the high-speed mixer can be subjected to special low-friction surface treatment (such as polishing or coating), or a low-friction inert material (such as a specific engineering plastic or stainless steel material) is selected.

[0041] In some embodiments, the crushing equipment (such as a crusher) used for crushing treatment in the S1 step is also subjected to special low-friction surface treatment (such as polishing or coating), or a low-friction inert material (such as a specific engineering plastic or stainless steel material) is selected.

[0042] Optionally, the S3 step uses a double-screw extruder to extrude the material; and a calender is used to press the melt into a sheet shape.

[0043] The third aspect of the present application provides an application of an epoxy plastic packaging material, which is applied to the packaging of an optical coupling product.

[0044] Advantages: The present application provides an epoxy plastic packaging material, a preparation method and an application thereof, which has the following advantages: (1) The present application introduces a multifunctional alkyd wax as a release agent in an epoxy resin curing system, and the unique amphiphilic molecular structure (epoxyophilic end: hydroxyl -OH; non-molecular end: long-chain alkyl) can promote the generation of a high-strength hydrogen bond network, effectively reduce the interface void, and realize low release force and extremely low chemical residue through van der Waals force. Compared with the performance of the epoxy plastic packaging material prepared by the traditional acid wax, the performance of the present application is more excellent, especially with a higher CTR.

[0045] (2) The hydrogen bond network formed by the multifunctional alkyd wax and the curing agent of the present application can moderately delay the curing reaction rate, reduce the curing shrinkage rate from 0.5% to 0.4%, effectively reduce the alignment deviation of LED and photosensitive devices caused by shrinkage stress; at the same time, the gel time is prolonged, the curing rate of the epoxy resin is delayed, and the stress release is beneficial.

[0046] (3) The silane coupling agent is preferably a methoxysilane coupling agent, which preferentially occupies the surface active sites of the filler (silicon powder), greatly improves the interfacial bonding strength of the filler-resin, effectively anchors the release agent molecules in the dense siloxane network, significantly inhibits the release agent from agglomerating and precipitating at the interface, thereby reducing the light scattering centers, reducing the light transmission loss, and further improving the CTR of the epoxy plastic encapsulant.

[0047] (4) The preparation process of the epoxy plastic encapsulant is further optimized. The raw materials are pretreated to reduce the particle size to below 30 mesh before mixing, which can maximize the reduction of shear friction while ensuring that the materials are fully melted and uniformly mixed, thereby optimizing the comprehensive performance of the epoxy plastic encapsulant.

[0048] (5) The raw materials are easy to obtain, the preparation process is simple and operable, and high-quality products can be efficiently prepared. The obtained epoxy plastic encapsulant has high CTR, low shrinkage, excellent release properties, and can well meet the packaging and use requirements of optical coupling products, and has a wide application prospect. DETAILED DESCRIPTION

[0049] The raw material information in the following examples and comparative examples is shown in Table 1 below.

[0050] Table 1

[0051] Unless otherwise specified, the raw materials, equipment, and other consumables used in the present application are commercially available.

[0052] Examples 1-3 and Comparative Examples 1-8 Examples 1-3 and Comparative Examples 1-8 each provide an epoxy plastic encapsulant. The formula of the epoxy plastic encapsulant is shown in Table 2. The values in Table 2 are in parts by weight.

[0053] Table 2

[0054] The preparation steps of the epoxy plastic encapsulant each include: S1. Pretreatment: using a pulverizer to pulverize the epoxy resin, release agent, catalyst, filler, silane coupling agent, and curing agent, respectively, to a particle size of 30 mesh or less; S2. Mixing: transferring the pulverized epoxy resin, release agent, catalyst, filler, silane coupling agent, and curing agent to a high-speed mixer and mixing uniformly; S3. Extrusion: transferring the uniformly mixed material to a twin-screw extruder, extruding the melt, and using a calender to press the melt into a sheet to obtain the epoxy plastic encapsulant.

[0055] Performance Test 1. Processing performance The epoxy resin plastic encapsulating materials prepared from the examples and comparative examples were taken, and the spiral flow length, gel time and thermal hardness of the epoxy resin plastic encapsulating materials were determined according to the test method for epoxy plastic encapsulating materials for electronic packaging in GB / T 40564-2021; the test results are recorded in Table 3.

[0056] 2, Curing performance The epoxy resin plastic encapsulating materials prepared from the examples and comparative examples were taken, and the spiral flow length, gel time and thermal hardness of the epoxy resin plastic encapsulating materials were determined according to the test method for epoxy plastic encapsulating materials for electronic packaging in GB / T 40564-2021; the test results are recorded in Table 3.

[0057] Table 3

[0058] The test data of comparative examples 1-3 and comparative examples 1-2 can be seen that compared with the use of traditional release agents (acid wax or oxidized polyethylene wax), the introduction of multifunctional alkyd ester wax (which can be used alone or compounded with other release agents) in the epoxy resin curing system, the comprehensive performance of the optical coupling epoxy plastic encapsulating material is improved, especially the CTR of example 1 is increased to 214%, which is increased by 15% compared with the traditional release agent (the CTR of comparative example 1 is 186%). Further, the release force of the epoxy plastic encapsulating material of example 1 is reduced to 2N, which is reduced by 81% compared with the acid wax control group (comparative example 1: 10.8N) and reduced by 72% compared with the oxidized polyethylene wax group (comparative example 2: 7.2N). The release force is ranked as example 1 (2N) < example 2 (4N) < example 3 (6.5N) << traditional release agent group. The experimental data proves that the complete replacement effect of multifunctional alkyd ester wax is the best, and the release force of the epoxy plastic encapsulating material is the lowest. At the same time, example 1 has the industry-leading low shrinkage characteristics (the shrinkage rates of comparative examples 1 and 2 are higher), which further verifies that the hydrogen bond network constructed by alkyd ester wax-curing agent has excellent stress inhibition ability, effectively reducing the shrinkage tendency of the epoxy plastic encapsulating material. The gel time of the epoxy plastic encapsulating material of example 1 can be extended to 16s, while the gel time of the epoxy plastic encapsulating material using traditional release agents (comparative examples 1 and 2) is 12-13s, which indicates that the curing rate of the resin is delayed after the introduction of alkyd ester wax, which is beneficial to the release of stress.

[0059] Different silane coupling agents are selected in comparative examples 3-8, and the total amount of the silane coupling agent is controlled to be the same, and the performance of the epoxy plastic encapsulating material appears differences. Comparative example 3 uses a single methoxysilane coupling agent, which has good release performance, and the bending strength at room temperature is obviously higher than that of the epoxy plastic encapsulating material prepared from other silane coupling agents, which proves that the methoxysilane coupling agent can improve the interfacial bonding strength, anchor the release agent with the siloxane network, and further reduce light scattering and light transmission loss; while selecting other types of silane coupling agents cannot achieve similar effects.

Claims

1. An epoxy molding compound, characterized in that, The raw materials for preparing the epoxy molding compound, by weight, include: 40-80 parts epoxy resin, 1-10 parts release agent, 0.1-3 parts catalyst, 50-500 parts filler, 0.1-5 parts silane coupling agent, and 20-60 parts curing agent. The release agent includes at least alkyd ester waxes; The silane coupling agent includes a methoxysilane coupling agent.

2. The epoxy molding compound according to claim 1, characterized in that, The release agent also includes oxidized polyethylene wax or acid wax.

3. The epoxy molding compound according to claim 1, characterized in that, The epoxy resin includes o-cresol-type epoxy resin and bisphenol A-type epoxy resin; the mass ratio of the o-cresol-type epoxy resin and the bisphenol A-type epoxy resin is (1.5-5):

1.

4. The epoxy molding compound according to claim 3, characterized in that, The curing agent includes one or more of linear phenolic resin, BPA phenolic resin, and acid anhydride.

5. The epoxy molding compound according to claim 3, characterized in that, The equivalent ratio of the active groups in the curing agent to the epoxy groups in the epoxy resin is (0.5-1.5):

1.

6. The epoxy molding compound according to claim 1, characterized in that, The filler includes silicon powder with a median particle size of 10-30 μm; the amount of filler added is 60-80% of the total mass of the epoxy molding compound.

7. The epoxy molding compound according to claim 1, characterized in that, The CTR of the epoxy molding compound is above 195%.

8. A method for preparing the epoxy molding compound according to claim 1, characterized in that, The preparation steps of the epoxy molding compound include: S1. The epoxy resin, release agent, catalyst, filler, silane coupling agent, and curing agent are pulverized separately. S2. Mix the pulverized epoxy resin, release agent, catalyst, filler, silane coupling agent, and curing agent evenly; S3. Transfer the uniformly mixed material to an extruder, extrude the melt, compress and shape it to obtain epoxy molding compound.

9. The method for preparing epoxy molding compound according to claim 8, characterized in that, In step S1, the particles are pulverized to a particle size of less than 30 mesh.

10. An application of an epoxy molding compound according to any one of claims 1-7, characterized in that, The epoxy molding compound is used for the encapsulation of optocoupler products.

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