A phosphorus-free and acid anhydride-free epoxy encapsulating material and preparation method thereof

Abstract

The present invention relates to the technical field of electronic component packaging materials, and in particular to a phosphorus-free and anhydride-free epoxy encapsulant and a preparation method thereof. The components and mass fractions of the phosphorus-free and anhydride-free epoxy encapsulant are as follows: bisphenol A epoxy resin, 35 to 50 parts; dimethyl imidazole, 0.1 to 1 part; dicyandiamide, 0 to 1 part; melamine cyanurate, 8 to 15 parts; toughening agent, 2 to 8 parts; filler, 35 to 50 parts; auxiliary agent, 4 to 8 parts. The epoxy encapsulant provided by the present invention does not contain phosphorus and anhydride in the formula composition, and melamine cyanurate replaces conventional anhydride curing agent and phosphorus-containing flame retardant, which can not only achieve the same flame retardant effect as phosphorus-containing flame retardant, but also does not produce toxic gases, which is more green and environmentally friendly. At the same time, the present invention also provides a method for preparing a phosphorus-free and anhydride-free epoxy encapsulant, which is simple and easy to operate, has mild preparation conditions, and is easy to mass produce.

Description

Technical Field

[0001] The invention relates to the technical field of electronic component packaging materials, and in particular to a phosphorus-free and acid anhydride-free epoxy encapsulating material and a preparation method thereof. Background Art

[0002] At present, epoxy powder encapsulation materials mostly use anhydride substances as curing agents, especially trimellitic anhydride (TMA), which is a more commonly used curing agent. In recent years, trimellitic anhydride has been identified as a substance of very high concern (SVHC) due to its respiratory sensitization properties. Data show that if the exposure to TMA is prolonged and no intervention measures are taken, trimellitic anhydride will cause serious and permanent damage to lung function. In addition, existing epoxy powder encapsulation materials mostly use organophosphorus flame retardants, which are semi-volatile and easily accumulated in organisms, posing potential hazards to the environment and human health. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems existing in the related art. To this end, the first object of the present invention is to provide a phosphorus-free and anhydride-free epoxy encapsulant; the second object of the present invention is to provide a method for preparing the phosphorus-free and anhydride-free epoxy encapsulant.

[0004] In order to achieve the first purpose, the technical solution adopted by the present invention is:

[0005] A phosphorus-free and anhydride-free epoxy encapsulant, the composition and mass fractions of which are as follows:

[0006] Bisphenol A epoxy resin mixture, 35 to 50 parts;

[0007] Dimethylimidazole, 0.1 to 1 part;

[0008] Dicyandiamide, 0 to 1 part;

[0009] Melamine cyanurate, 8 to 15 parts;

[0010] Toughening agent, 2 to 8 parts;

[0011] Filler, 35 to 50 parts;

[0012] Auxiliary agent: 4 to 8 parts.

[0013] Furthermore, its composition and mass fractions are as follows:

[0014] Bisphenol A epoxy resin, 37 to 40 parts;

[0015] Dimethylimidazole, 0.2 to 0.4 parts;

[0016] Dicyandiamide, 0 to 0.5 parts;

[0017] Melamine cyanurate, 8 to 14 parts;

[0018] Toughening agent, 2.3 to 6 parts;

[0019] Filler, 36 to 46 parts;

[0020] Auxiliary agent: 5.3 to 6 parts.

[0021] Furthermore, the toughening agent includes at least one of a silicone toughening agent, a polyacrylate toughening agent and hollow glass microspheres.

[0022] Furthermore, the filler includes at least one of silicon micropowder, calcium carbonate, calcium silicate and hydrotalcite.

[0023] Furthermore, the auxiliary agent includes at least one of a leveling agent, a colorant, a marking agent and a lubricating dispersant.

[0024] In order to achieve the second purpose, the technical solution adopted by the present invention is:

[0025] A method for preparing a phosphorus-free and anhydride-free epoxy encapsulant, which is used to prepare any of the above-mentioned phosphorus-free and anhydride-free epoxy encapsulant, comprises the following steps:

[0026] S100, weighing the raw materials according to their composition and mass fraction, and mixing them evenly to obtain a first mixed material;

[0027] S200, adding the mixed material into an extruder, setting the temperature and the rotation speed, and making the bisphenol A epoxy resin melt and then mix it evenly with other components to obtain a second mixed material;

[0028] S300, cooling the second mixed material by a cooling roller, crushing it, and collecting particles of a desired particle size through air separation and screening to obtain a phosphorus-free and acid anhydride-free epoxy encapsulant.

[0029] Furthermore, the method further comprises the following steps:

[0030] S400, adding a thixotropic agent to the phosphorus-free and anhydride-free epoxy encapsulant obtained in step S300, and mixing the mixture evenly to make the phosphorus-free and anhydride-free epoxy encapsulant fluidized and fluffy.

[0031] Furthermore, in step S200, the temperature is set at 120°C to 140°C, and the rotation speed is set at 200 r / min to 400 r / min.

[0032] Furthermore, in step S200, the temperature is set at 130°C and the rotation speed is set at 200r / min.

[0033] Furthermore, in step S200, the extruder is a twin-screw extruder.

[0034] The above one or more technical solutions in the embodiments of the present invention have at least one of the following technical effects:

[0035] The epoxy encapsulant provided by the present invention does not contain phosphorus and anhydride in its formula composition. Melamine cyanurate (MCA for short) replaces conventional anhydride curing agents and phosphorus-containing flame retardants, which can not only achieve the same flame retardant effect as phosphorus-containing flame retardants (can reach UL94 V-0 level), but also does not produce toxic gases, which is more environmentally friendly. At the same time, the present invention also provides a method for preparing a phosphorus-free and anhydride-free epoxy encapsulant, which is simple and easy to operate, has mild preparation conditions, and is easy to mass produce.

[0036] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme in the present invention will be clearly and completely described below in conjunction with the specific embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention. The following embodiments are used to illustrate the present invention, but cannot be used to limit the scope of the present invention.

[0038] A phosphorus-free and anhydride-free epoxy encapsulant, the composition and mass fractions of which are as follows:

[0039] Bisphenol A epoxy resin, 35 to 50 parts;

[0040] Dimethylimidazole, 0.1 to 1 part;

[0041] Dicyandiamide, 0 to 1 part;

[0042] Melamine cyanurate, 8 to 15 parts;

[0043] Toughening agent, 2 to 8 parts;

[0044] Filler, 35 to 50 parts;

[0045] Auxiliary agent: 4 to 8 parts.

[0046] In the formula composition of the phosphorus-free and anhydride-free epoxy encapsulant provided by the present invention, melamine cyanurate is used as a curing agent, and bisphenol A epoxy resin reacts with melamine cyanurate to form a polymer containing a nitrogen structure, which synergistically cooperates with excess melamine cyanurate that does not participate in the reaction to achieve a flame retardant effect.

[0047] The difference between the present invention and the prior art is that melamine cyanurate (MCA) is used in the formula composition to replace conventional anhydride curing agents and phosphorus-containing flame retardants, which can not only achieve the same flame retardant effect as phosphorus-containing flame retardants (can reach UL94 V-0 level), but also does not produce toxic gases, and has little effect on the viscosity of epoxy resin. Its flame retardant mechanism is to generate non-combustible gas to dilute combustibles through decomposition, sublimation, heat absorption and gas phase flame retardancy to play a flame retardant role. The present invention uses melamine cyanurate as a curing agent for epoxy resin. Its mechanism is to use the cyanamide group in the structure of melamine cyanurate (MCA) to react with the epoxy group of epoxy resin to form a ring contraction structure, which can replace the anhydride curing agent to play a role in curing and cross-linking.

[0048] In the following examples, the experimental methods used are conventional methods unless otherwise specified, and the materials, reagents, etc. used are all available from commercial sources unless otherwise specified.

[0049] Example 1

[0050] 37 parts by mass of bisphenol A epoxy resin, 0.4 parts by mass of dimethyl imidazole, 0.5 parts by mass of dicyandiamide, 8 parts by mass of melamine cyanurate, 2.3 parts by mass of toughening agent ethylene ethyl acrylate, 46 parts by mass of filler silicon powder, and 5.8 parts by mass of other additives (1.3 parts by mass of polybutyl acrylate, 1.5 parts of phthalocyanine blue, 3 parts of titanium dioxide) were put into a high-speed mixer in proportion and mixed for 3 minutes. The mixture was added to a twin-screw extruder, the temperature was set at 130°C, and the extrusion speed was set at 200r / min. The resin was melted under the shearing state of the screw and mixed evenly with other raw materials. After the melt was cooled by the cooling roller, it entered the ACM mill for crushing. After the air selection process and screening, the particles of the required particle size were collected, and finally an external thixotropic agent was added to make the powder fluidized and fluffy.

[0051] Example 2

[0052] 38 parts by mass of bisphenol A epoxy resin, 0.3 parts by mass of dimethylimidazole, 14 parts by mass of melamine cyanurate, 6 parts by mass of toughening agent ethylene ethyl acrylate, 36.4 parts by mass of filler silicon powder, and 5.3 parts by mass of other additives (0.8 parts by mass of polybutyl acrylate, 1.5 parts of phthalocyanine blue, and 3 parts of titanium dioxide) were put into a high-speed mixer in proportion and mixed for 3 minutes. The mixture was added to a twin-screw extruder, the temperature was set at 130°C, and the extrusion speed was set at 200r / min. The resin was melted under the shearing state of the screw and mixed evenly with other raw materials. After the melt was cooled by the cooling roller, it entered the ACM mill for crushing. After the air selection process and screening, the particles of the required particle size were collected, and finally an external thixotropic agent was added to make the powder fluidized and fluffy.

[0053] Example 3

[0054] 40 parts by mass of bisphenol A epoxy resin, 0.2 parts by mass of dimethyl imidazole, 0.1 parts by mass of dicyandiamide, 12 parts by mass of melamine cyanurate, 4.7 parts by mass of toughening agent ethylene ethyl acrylate, 37 parts by mass of filler silicon powder, and 6 parts by mass of other additives (1.5 parts by mass of polybutyl acrylate, 1.5 parts by mass of phthalocyanine blue, and 3 parts by mass of titanium dioxide) were put into a high-speed mixer in proportion and mixed for 3 minutes. The mixture was added to a twin-screw extruder, the temperature was set at 130°C, and the extrusion speed was set at 200r / min. The resin was melted under the shearing state of the screw and mixed evenly with other raw materials. After the melt was cooled by the cooling roller, it entered the ACM mill for crushing. After the air selection process and screening, the particles of the required particle size were collected, and finally an external thixotropic agent was added to make the powder fluidized and fluffy.

[0055] Example 4

[0056] 40 parts by mass of bisphenol A epoxy resin, 0.3 parts by mass of dimethyl imidazole, 0.2 parts by mass of dicyandiamide, 10 parts by mass of melamine cyanurate, 3.7 parts by mass of toughening agent ethylene ethyl acrylate, 40 parts by mass of filler silicon powder, and 5.8 parts by mass of other additives (1.3 parts by mass of polybutyl acrylate, 1.5 parts of phthalocyanine blue, 3 parts of titanium dioxide) were put into a high-speed mixer in proportion and mixed for 3 minutes. The mixture was added to a twin-screw extruder, the temperature was set at 130°C, and the extrusion speed was set at 200r / min. The resin was melted under the shearing state of the screw and mixed evenly with other raw materials. After the melt was cooled by the cooling roller, it entered the ACM mill for crushing. After the air selection process and screening, the particles of the required particle size were collected, and finally an external thixotropic agent was added to make the powder fluidized and fluffy.

[0057] Comparative Example 1

[0058] 39.4 parts by mass of bisphenol A epoxy resin, 3.2 parts by mass of trimellitic anhydride, 0.05 parts by mass of dimethylimidazole, 4.7 parts by mass of organophosphorus flame retardant, 37.1 parts by mass of filler silicon powder, 13.3 parts by mass of aluminum hydroxide, 1.5 parts by mass of phthalocyanine blue, and 0.8 parts by mass of polybutyl acrylate are put into a high-speed mixer in proportion and mixed for 3 minutes. The mixture is added to a twin-screw extruder, the temperature is set at 130°C, and the extrusion speed is set at 200r / min. After the resin is melted under the shearing state of the screw, it is mixed evenly with other raw materials. After the melt is cooled by the cooling roller, it enters the ACM grinder for crushing. After the air selection process and screening, the particles of the required particle size are collected, and finally an external thixotropic agent is added to make the powder fluidized and fluffy.

[0059] Comparative Example 2

[0060] 42.6 parts by mass of bisphenol A epoxy resin, 5.1 parts by mass of trimellitic anhydride, 0.05 parts by mass of dimethylimidazole, 7 parts by mass of organophosphorus flame retardant, 28.4 parts by mass of filler silicon powder, 20.3 parts by mass of aluminum hydroxide, 1.5 parts by mass of phthalocyanine blue, and 0.8 parts by mass of polybutyl acrylate are put into a high-speed mixer in proportion and mixed for 3 minutes. The mixture is added to a twin-screw extruder, the temperature is set at 130°C, and the extrusion speed is set at 200r / min. The resin is melted under the shearing state of the screw and mixed evenly with other raw materials. After the melt is cooled by the cooling roller, it enters the ACM grinder for crushing. After the air selection process and screening, the particles of the required particle size are collected, and finally an external thixotropic agent is added to make the powder fluidized and fluffy.

[0061] Comparative Example 3

[0062] 31.5 parts by mass of bisphenol A epoxy resin, 21 parts by mass of toughened modified epoxy resin, 3.3 parts by mass of pyromellitic anhydride, 0.05 parts by mass of dimethyl imidazole, 7 parts by mass of melamine cyanurate, 5.6 parts by mass of zinc stannate, 8.4 parts by mass of filler silicon micropowder, 21 parts by mass of aluminum hydroxide, 1.5 parts by mass of phthalocyanine blue, and 1 part by mass of polybutyl acrylate are put into a high-speed mixer in proportion and mixed for 3 minutes. The mixture is added to a twin-screw extruder, the temperature is set at 130°C, and the extrusion speed is set at 200r / min. After the resin is melted under the shearing state of the screw, it is evenly mixed with other raw materials. After the melt is cooled by a cooling roller, it enters the ACM mill to break it, and after air selection and screening, the particles of the required particle size are collected, and finally an external thixotropic agent is added to make the powder fluidized and fluffy.

[0063] Comparative Example 4

[0064] 21 parts by weight of bisphenol A epoxy resin, 36 parts by weight of toughened modified epoxy resin, 3.1 parts by weight of pyromellitic anhydride, 0.05 parts by weight of dimethylimidazole, 7 parts by weight of melamine cyanurate, 5.6 parts by weight of zinc stannate, 8.4 parts by weight of filler silicon micropowder, 21 parts by weight of aluminum hydroxide, 1.5 parts by weight of phthalocyanine blue, and 1 part by weight of polybutyl acrylate are put into a high-speed mixer in proportion and mixed for 3 minutes. The mixture is added to a twin-screw extruder, the temperature is set at 130°C, and the extrusion speed is set at 200r / min. After the resin is melted under the screw shearing state, it is evenly mixed with other raw materials. After the melt is cooled by a cooling roller, it enters the ACM mill for crushing. After air separation and screening, particles of the required particle size are collected, and finally an external thixotropic agent is added to make the powder fluidized and fluffy.

[0065] Detection items and methods related to the present invention:

[0066] Gel time: tested according to the method described in GB / T 28860-2012.

[0067] Horizontal flow rate: tested according to the method described in Q / 12DJ4454-2021.

[0068] Needle flame test is based on the method described in GB / T 5169.5-2008.

[0069] Resistance to cold and hot shock: According to the method 5.2.9 in GB / T28859-2012 "Epoxy Powder Encapsulation Materials for Electronic Components", encapsulate 10 components of about φ20mm×(1~2)mm, and keep them at -55℃ for 0.5h, then heat up to 125℃ and keep them for 0.5h. The above is considered as a cycle. Observe whether the appearance of the component is cracked after a certain number of test cycles. If cracking occurs, it is judged as failure. The reference indicator requirement is that there is no cracking after 5 tests.

[0070] Varistor PCT experiment: Encapsulate varistor 14D561, single layer thickness is 0.4-0.6mm, curing conditions are 150℃ / 90 minutes, 10pcs per group. Test varistor voltage, nonlinear coefficient, and leakage current before the experiment. Place the sample in a sterilizer at 121℃, steam in air for 12h, dry for 4h, and test varistor voltage, nonlinear coefficient, and leakage current. Reference index requirements: Varistor voltage change rate before and after the experiment is less than 10%, and leakage current after the experiment is less than 100μA.

[0071] Ceramic capacitor PCT experiment: Encapsulated ceramic capacitor 472M, single layer thickness of 0.4 ~ 0.6mm, curing conditions of 150 ℃ / 90 minutes, 10pcs per group. Before the experiment, test the capacity, loss, insulation resistance, AC4KV-60s withstand voltage. Place the sample in the sterilizer, 121 ℃, steam in air for 12h, dry for 4h, test the capacity, loss, insulation resistance, AC4KV-60s withstand voltage. Reference index requirements: After the experiment, the insulation resistance is greater than 10GΩ, and there is no withstand voltage failure at AC4KV-60s.

[0072] The test results are shown in Table 1 and Table 2:

[0073] Table 1 Performance test results of epoxy encapsulants prepared in Examples 1 to 4

[0074]

[0075] Table 2 Performance test results of epoxy encapsulants prepared in Comparative Examples 1 to 4

[0076]

[0077] It can be seen from Table 1 that Examples 1 to 4 can meet the reliability and flame retardancy requirements of epoxy encapsulants. Combining Table 1 and Table 2, it can be seen that the use of melamine cyanurate as a curing agent in the present invention instead of an anhydride curing agent can meet the reliability requirements of epoxy encapsulants. The varistor PCT experiment shows that the epoxy encapsulants provided by Examples 1 to 4 have better moisture resistance than the encapsulants provided by Comparative Examples 1 to 4.

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A phosphorus-free and anhydride-free epoxy encapsulant, characterized in that: Its composition and mass fraction are as follows: Bisphenol A epoxy resin, 35 to 50 parts; Dimethylimidazole, 0.1 to 1 part; Dicyandiamide, 0 to 1 part; Melamine cyanurate, 8 to 15 parts; Toughening agent, 2 to 8 parts; Filler, 35 to 50 parts; Additives: 4 to 8 parts.

2. The phosphorus-free and anhydride-free epoxy encapsulant as claimed in claim 1, characterized in that: Its composition and mass fraction are as follows: Bisphenol A epoxy resin, 37 to 40 parts; Dimethylimidazole, 0.2 to 0.4 parts; Dicyandiamide, 0 to 0.5 parts; Melamine cyanurate, 8 to 14 parts; Toughening agent, 2.3 to 6 parts; Filler, 36 to 46 parts; Auxiliary agent: 5.3 to 6 parts.

3. The phosphorus-free and anhydride-free epoxy encapsulant as claimed in claim 1, characterized in that: The toughening agent includes at least one of an organosilicon toughening agent, a polyacrylate toughening agent and hollow glass microspheres.

4. The phosphorus-free and anhydride-free epoxy encapsulant as claimed in claim 1, characterized in that: The filler includes at least one of silicon micropowder, calcium carbonate, calcium silicate and hydrotalcite.

5. The phosphorus-free and anhydride-free epoxy encapsulant as claimed in claim 1, characterized in that: The auxiliary agent includes at least one of a leveling agent, a colorant, a marking agent and a lubricating dispersant.

6. A method for preparing a phosphorus-free and anhydride-free epoxy encapsulant, characterized in that: The method for preparing the phosphorus-free and anhydride-free epoxy encapsulant according to any one of claims 1 to 5 comprises the following steps: S100, weighing the raw materials according to their composition and mass fraction, and mixing them evenly to obtain a first mixed material; S200, adding the mixed material into an extruder, setting the temperature and the rotation speed, and making the bisphenol A epoxy resin melt and then mix it evenly with other components to obtain a second mixed material; S300, cooling the second mixed material by a cooling roller, crushing it, and collecting particles of a desired particle size through a wind selection process and screening to obtain a phosphorus-free and acid anhydride-free epoxy encapsulant.

7. The method for preparing the phosphorus-free and anhydride-free epoxy encapsulant as claimed in claim 6, characterized in that: The following steps are also included: S400, adding a thixotropic agent to the phosphorus-free and anhydride-free epoxy encapsulant obtained in step S300, and mixing the mixture evenly to make the phosphorus-free and anhydride-free epoxy encapsulant fluidized and fluffy.

8. The method for preparing the phosphorus-free and anhydride-free epoxy encapsulant as claimed in claim 6, characterized in that: In step S200, the temperature is set at 120°C to 140°C, and the rotation speed is set at 200 r / min to 400 r / min.

9. The method for preparing the phosphorus-free and anhydride-free epoxy encapsulant as claimed in claim 8, characterized in that: In step S200, the temperature is set to 130°C and the rotation speed is set to 200 r / min.

10. The method for preparing the phosphorus-free and anhydride-free epoxy encapsulant according to claim 6, characterized in that: In step S200, the extruder is a twin-screw extruder.

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