Electromagnetic wave shielding resin composition and cured matter thereof

Abstract

To provide: an electromagnetic wave shielding resin composition with which it is possible to obtain a cured matter having electromagnetic wave shielding performance at high frequency while maintaining insulation properties; and a cured matter of the composition.SOLUTION: An electromagnetic wave shielding resin composition includes epoxy resin, and a complex of poly(3,4-ethylenedioxythiophene) and poly(4-styrenesulfonic acid). A content of the complex of poly(3,4-ethylenedioxythiophene) and poly(4-styrenesulfonic acid) is 0.2-6.0 mass%.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to an electromagnetic wave suppression resin composition and a cured product thereof. [Background technology]

[0002] In resin-encapsulated semiconductor devices, a method for preventing electromagnetic wave interference, such as preventing malfunctions of equipment due to electromagnetic noise, is known in which the encapsulation resin of the semiconductor element is given electromagnetic wave suppression capabilities. In this case, since the electromagnetic wave oscillator is located close to the encapsulation resin, measures against electromagnetic waves in the near field are necessary. At the same time, since the encapsulation resin comes into contact with the active part of the element, the encapsulation resin is required to have insulating properties.

[0003] Known materials that impart electromagnetic wave suppression capabilities generally include metals such as iron and aluminum, alloys and metal oxides of magnetic materials such as sendust and ferrite, and carbon materials such as carbon nanotubes (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2021 / 241541 Summary of the Invention [Problem to be solved by the invention]

[0005] However, none of the above materials can be said to have sufficient insulating properties when used as a sealing resin.

[0006] Incidentally, it is known to use a conductive polymer, such as a composite of poly(3,4-ethylenedioxythiophene) (PEDOT) and poly(4-styrenesulfonic acid) (PSS) (abbreviated as PEDOT / PSS), for the impedance matching layer of an electromagnetic wave absorber. However, due to their electrical conductivity, the application of such conductive polymers as sealing resins for suppressing electromagnetic waves has not been studied to date.

[0007] The present inventors have focused on a particular conductive polymer and have repeatedly investigated its application to sealing resins in order to achieve both electromagnetic wave suppression capability and insulating properties.

[0008] The present disclosure has been made in light of these circumstances, and aims to provide an electromagnetic wave suppression resin composition that can yield a cured product that has electromagnetic wave suppression capabilities at high frequencies while retaining insulation properties, and a cured product thereof. [Means for solving the problem]

[0009] The present disclosure is based on the discovery that an encapsulating resin containing a predetermined amount of PEDOT / PSS has the ability to suppress high-frequency electromagnetic waves in the near field and can maintain insulation properties.

[0010] That is, the present disclosure relates to the following: [1] An electromagnetic wave suppression resin composition comprising an epoxy resin and a composite of poly(3,4-ethylenedioxythiophene) and poly(4-styrenesulfonic acid), wherein the content of the composite of poly(3,4-ethylenedioxythiophene) and poly(4-styrenesulfonic acid) is 0.2 to 6.0 mass %. [2] The electromagnetic wave suppression resin composition of [1], wherein the epoxy resin has a polyoxyalkylene structure. [3] The electromagnetic wave suppression resin composition of [1] or [2], further comprising a filler. [4] The electromagnetic wave suppression resin composition of [3], wherein the filler content is 30.0 to 95.0 mass %. [5] The electromagnetic wave suppression resin composition according to [4], which is a sheet-forming material, wherein the filler content is 30.0 to 90.0 mass %. [6] The electromagnetic wave suppression resin composition according to [4], which is a semiconductor encapsulation material, wherein the filler content is 60.0 to 95.0 mass %. [7] A cured product of the electromagnetic wave suppression resin composition according to any one of [1] to [6]. [Effects of the Invention]

[0011] The present disclosure provides an electromagnetic wave suppression resin composition that can be used to obtain a cured product that has electromagnetic wave suppression capabilities at high frequencies while maintaining insulation properties, and a cured product thereof. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, the present disclosure will be described in detail with reference to an embodiment. The meanings and definitions of terms used in this disclosure are as follows: A numerical range expressed by "to" means a numerical range in which the numerical values before and after "to" are the lower and upper limits. For numerical ranges (e.g., ranges of content, etc.), lower and upper limits described in stages may be combined independently. The lower and upper limits of a numerical range may be replaced with numerical values described in the examples.

[0013] [Electromagnetic wave suppressing resin composition] The electromagnetic wave suppression resin composition (hereinafter also simply referred to as a resin composition) of the present disclosure contains an epoxy resin and PEDOT / PSS, with the PEDOT / PSS content being 0.2 to 6.0 mass %. In this way, a resin composition in which a predetermined amount of PEDOT / PSS is blended with an epoxy resin can provide a cured product that has the ability to suppress electromagnetic waves at high frequencies while maintaining insulating properties.

[0014] (epoxy resin) The epoxy resin has two or more epoxy groups in one molecule and is not particularly limited in terms of molecular structure or molecular weight, as long as it is an epoxy resin commonly used in electronic components. The state is also not particularly limited, and the resin may be either liquid or solid at room temperature (25°C). Examples of epoxy resins include phenol novolac epoxy resins; cresol novolac epoxy resins; aliphatic epoxy resins such as dicyclopentadiene derivatives; and aromatic epoxy resins such as biphenyl, biphenyl aralkyl, naphthyl, and bisphenol types. The epoxy resins may be used alone or in combination of two or more. Among these, cresol novolac epoxy resins and bisphenol epoxy resins are preferred. The bisphenol epoxy resin may be bisphenol A or bisphenol F, or may be bisphenol A.

[0015] The epoxy resin may have a polyoxyalkylene structure. When the epoxy resin is a mixture containing a polyoxyalkylene structure, the mixing ratio of the epoxy resin having the polyoxyalkylene structure and the epoxy resin not having the polyoxyalkylene structure is not particularly limited. By including an epoxy resin having a polyoxyalkylene structure in the resin composition, it is possible to improve the electromagnetic wave suppression ability while maintaining the insulating properties.

[0016] The alkylene group constituting the polyoxyalkylene group may be a linear or branched alkylene group having 1 to 6 carbon atoms, from the viewpoint of improving the melt viscosity and electromagnetic wave suppression ability of the resin composition, etc. Specific examples of the alkylene group include a methylene group, ethylene group, trimethylene group, propylene group, tetramethylene group, and hexamethylene group, and may also be a methylene group or an ethylene group. The degree of polymerization of the polyoxyalkylene group (the number of repeating oxyalkylene groups) may be 2 to 50, or may be 2 to 20. The epoxy resin having a polyoxyalkylene structure may be, for example, one having a bisphenol A skeleton.

[0017] The epoxy equivalent of the epoxy resin may be 140 to 400 g / eq, 150 to 390 g / eq, or 160 to 380 g / eq, from the viewpoint of good insulation properties and thermal expansion coefficient of the cured product of the resin composition.

[0018] (PEDOT / PSS) PEDOT / PSS is known as a conductive polymer, but in the EMI suppression resin composition of the present disclosure, it is contained in a relatively small amount, which can impart EMI suppression capability at high frequencies (10 GHz) while minimizing a decrease in the volume resistivity of the cured product. Known examples of materials that impart electromagnetic wave suppression capability include carbon nanotubes (CNTs), which are carbon materials. CNTs have excellent thermal stability but high electrical conductivity. Therefore, even a small amount of CNTs (less than 0.5% by mass) in a resin composition significantly reduces the volume resistivity of the cured resin composition, making it unsuitable for near-field electromagnetic wave suppression in applications such as encapsulating resins that require insulation. The electromagnetic wave suppression resin composition of the present disclosure does not need to contain CNTs. Although PEDOT / PSS can be used as a conductive material, by using a specified amount, it is possible to achieve both electromagnetic wave suppression ability and insulating properties in the cured resin composition, and it can be suitably applied to encapsulating resins that require electromagnetic wave suppression ability in the near field.

[0019] The content of PEDOT / PSS in the resin composition is set to 0.2 to 6.0% by mass from the viewpoint of the electromagnetic wave suppression ability and insulating properties of the cured product of the resin composition. If the PEDOT / PSS content is less than 0.2% by mass, it is difficult to impart high-frequency electromagnetic wave suppression capability to the cured product of the resin composition, whereas if the PEDOT / PSS content is more than 6.0% by mass, the volume resistivity of the cured product of the resin composition is reduced, making it difficult to ensure insulation. The content of PEDOT / PSS may be 0.3 to 5.0% by mass, or 0.5 to 3.0% by mass.

[0020] Commercially available PEDOT / PSS can be used, and in order to obtain a cured product of a resin composition with high volume resistivity, a PEDOT / PSS film with high sheet resistance may be used, such as "CV10" manufactured by Kleba Corporation. Although PEDOT / PSS is generally dispersed in a liquid medium such as water, the liquid medium volatilizes during preparation of the resin composition, and therefore the resin composition of the present disclosure does not contain a liquid medium.

[0021] (filling material) The electromagnetic wave suppression resin composition of the present disclosure may further contain a filler from the standpoint of improving the heat resistance and strength of the cured product, reducing costs, and the like. The filler is not particularly limited as long as it is one that is generally used for resins in electronic components, and may be an inorganic filler that has a high dielectric constant and a high dielectric loss tangent. The filler may be, for example, an inorganic filler such as silica, alumina, magnesium oxide, titanium oxide, barium titanate, silicon nitride, aluminum nitride, silicon carbide, or tungsten carbide. These inorganic fillers may be used in combination with an organic substance from the viewpoint of improving dispersibility in the resin composition. The fillers may be used alone or in combination of two or more. Among these, silica and alumina may be used from the viewpoints of improving the electromagnetic wave suppression ability of the cured product of the resin composition, reducing the thermal expansion coefficient, and cost.

[0022] The form of the filler is not particularly limited, but from the viewpoint of being evenly contained in the resin composition, it may be, for example, powder, flake, fibrous particles, or the like, or may be powder or spherical. The average particle size of the filler particles is not particularly limited, but may be 0.1 to 100 μm, 0.2 to 75 μm, or 0.3 to 50 μm from the viewpoints of dispersibility in the resin composition, good fluidity of the resin composition, etc. Two or more types of particles having different average particle sizes may be used in combination. The average particle size in this specification refers to the volume average particle size, which is the median diameter of the equivalent sphere diameters of particles measured with a laser diffraction particle size distribution analyzer.

[0023] The content of the filler in the resin composition may be 30.0 to 95.0 mass %, 35.0 to 93.0 mass %, or 40.0 to 80.0 mass %, from the viewpoints of achieving appropriate fluidity and improving the heat resistance and strength of the cured product of the resin composition.

[0024] When the resin composition is used as a sheet-forming material, the content of the filler in the resin composition may be 30.0 to 90.0 mass%, 35.0 to 70.0 mass%, or 40.0 to 50.0 mass%, from the viewpoints of good moldability of the resin composition and the electromagnetic wave suppression ability of a cured product of the resin composition. In this case, the content of the epoxy resin in the resin composition may be 40.0 to 70.0 mass%, 45.0 to 65.0 mass%, or 50.0 to 60.0 mass%, from the viewpoint of appropriate fluidity and good moldability of the resin composition.

[0025] When the resin composition is used as a semiconductor encapsulating material, the content of the filler in the resin composition may be 60.0 to 95.0 mass %, 65.0 to 93.0 mass %, or 70.0 to 90.0 mass %, from the viewpoints of reducing the thermal expansion coefficient of the cured product of the resin composition and improving the electromagnetic wave suppression ability. In this case, the content of the epoxy resin in the resin composition may be 3.0 to 35.0 mass%, 4.0 to 30.0 mass%, or 5.0 to 20.0 mass%, from the viewpoints of appropriate fluidity of the resin composition and the thermal expansion coefficient of a cured product of the resin composition.

[0026] (hardening agent and hardening accelerator) The electromagnetic wave suppression resin composition of the present disclosure may further include a curing agent and may further include a curing accelerator. Examples of the curing agent include imidazole compounds, phenolic resins, acid anhydrides, aliphatic amines, aromatic amines, dicyandiamide, dihydrazide compounds, etc. The curing agents may be used alone or in combination of two or more. Examples of the curing accelerator include imidazole compounds, tertiary amines, phosphorus compounds, urea compounds, etc. One type of curing accelerator may be used alone, or two or more types may be used in combination.

[0027] When the resin composition is used as a sheet-forming material, it may contain, for example, an imidazole compound as a curing agent, and specifically, it may contain 1,2-dimethylimidazole or the like. In this case, the content of the curing agent in the resin composition may be 0.1 to 5.0 mass%, 0.2 to 3.0 mass%, or 0.3 to 2.0 mass%, from the viewpoint of appropriate curing properties when forming a sheet. In this case, the content of the curing agent may be 0.5 to 10 parts by mass, 1 to 5 parts by mass, or 1.5 to 3 parts by mass relative to 100 parts by mass of the epoxy resin.

[0028] When the resin composition is used as a semiconductor encapsulation material, it may contain, for example, a phenol resin as a curing agent, specifically, a phenol novolac resin or the like. In this case, the content of the curing agent in the resin composition may be 0.1 to 15.0 mass %, 0.5 to 10.0 mass %, or 1.0 to 8.0 mass %, from the viewpoint of appropriate curability for semiconductor encapsulation. In this case, the content of the curing agent may be 30 to 60 parts by mass, 35 to 55 parts by mass, or 40 to 50 parts by mass relative to 100 parts by mass of the epoxy resin.

[0029] In this case, an imidazole compound may further be contained as a curing accelerator, specifically, 2-heptadecylimidazole or the like. In this case, the content of the curing accelerator in the resin composition may be 0.01 to 5.0 mass%, 0.05 to 3.0 mass%, or 0.1 to 1.0 mass%, from the viewpoint of appropriate curing acceleration for semiconductor encapsulation. In this case, the content of the curing accelerator may be 1 to 10 parts by mass, 1.5 to 8 parts by mass, or 2 to 5 parts by mass relative to 100 parts by mass of the epoxy resin.

[0030] (Other ingredients) In addition to the components described above, the electromagnetic wave suppression resin composition of the present disclosure may also contain additives commonly used in resins for electronic components, depending on the physical property requirements of the cured product, as long as the addition does not deviate from the gist of the present disclosure. Examples of additives include flame retardants such as phosphazene compounds; release agents such as synthetic waxes, natural waxes, higher fatty acids, and esters of higher fatty acids; colorants such as cobalt blue; modifiers such as silicone oils and silicone rubbers; hydrotalcites; ion scavengers, etc. The additives may be used alone or in combination of two or more.

[0031] The total content of additives in the resin composition may be within a range that does not impair the effects of the electromagnetic wave suppression resin composition of the present disclosure, and may be 0 to 2.0 mass %, 0 to 1.5 mass %, or 0 to 1.2 mass %.

[0032] (Manufacturing method) The electromagnetic wave suppression resin composition of the present disclosure can be obtained by mixing an epoxy resin, PEDOT / PSS, and, as optional components, a curing agent, a curing accelerator, and other additives. For example, the components can be blended and thoroughly mixed using a universal mixer, Henschel mixer, or the like, and then melt-kneaded using a disperse mixer, kneader, three-roll mill, twin-screw roll mixer, twin-screw extrusion mixer, or the like. The temperature during melt kneading is a temperature at which the curing reaction of the resin composition does not proceed, and may be 70 to 170°C, 75 to 165°C, or 80 to 160°C.

[0033] The melt-kneaded resin composition may be cooled and solidified, and then pulverized to an appropriate size that is easy to handle using a cutting mill, ball mill, cyclone mill, hammer mill, vibration mill, cutter mill, grinder mill, speed mill, or the like.

[0034] The melt-kneaded resin composition may be molded into a sheet using a cold roll, a compression molding machine, etc. The molding conditions may be, for example, a temperature of 50 to 100° C. and a pressure of 0.5 to 1.5 MPa.

[0035] [Cured product] The above-described electromagnetic wave suppression resin composition of the present disclosure is cured to obtain the cured product of the present disclosure.

[0036] A sheet-shaped molded product of the resin composition is thermally cured to obtain a sheet-shaped cured electromagnetic wave suppressor. The thermal curing conditions may be, for example, a temperature of 120 to 200°C, atmospheric pressure, or a pressure of 20 MPa or less.

[0037] When the resin composition is used as a semiconductor encapsulation material, for example, a resin-encapsulated electronic component can be obtained by coating a semiconductor element fixed on a substrate with the resin composition and then curing the composition. The resin encapsulation method is not particularly limited, and known methods can be used. For example, the transfer method and the compression method are common methods.

[0038] In addition to sheet-forming materials and semiconductor encapsulation materials, the electromagnetic wave suppressing resin composition of the present disclosure may also be used to produce electromagnetic wave suppressing materials such as electrical wire covering materials and various other molded products.

[0039] A cured product of the electromagnetic wave suppression resin composition of the present disclosure has electromagnetic wave suppression capabilities at high frequencies while retaining insulation properties. Therefore, it can be used not only as an electromagnetic wave absorber in the far field, but also in applications requiring electromagnetic wave suppression in the near field. Examples of applications include encapsulation resins for semiconductor elements and electromagnetic wave suppression sheets that are placed in close proximity to semiconductor devices. [Example]

[0040] The present disclosure will now be described in detail with reference to examples, but the present disclosure is not limited to these examples in any way.

[0041] [Examples 1 to 4 and Comparative Examples 1 to 4] The components were blended according to the composition shown in Table 1, mixed in a universal mixer, and then kneaded in a twin-screw roll kneader at 110°C until homogeneous to produce a resin composition for sheet-forming material.

[0042] [Examples 5 to 8 and Comparative Examples 5 to 8] The components were blended according to the composition shown in Table 2, mixed in a Henschel mixer, and then kneaded in a twin-screw roll kneader at 110°C until homogeneous. The resulting kneaded product was stretched into a sheet using a cold roll and then pulverized using a cutter mill to produce a resin composition for semiconductor encapsulation material with particle sizes of 0.1 to 3.0 μm.

[0043] Details of each component of the resin compositions produced in the Examples and Comparative Examples are as follows. <Epoxy resin> R140: "Epomic (registered trademark) R140" manufactured by Mitsui Fine Chemicals, Inc.; bisphenol A epoxy resin (polycondensation product of bisphenol A and epichlorohydrin), epoxy equivalent 189 g / eq BEO-60E: "Rikaresin (registered trademark) BEO-60E" manufactured by New Japan Chemical Co., Ltd.; bisphenol A bis(triethylene glycol glycidyl ether) ether, epoxy equivalent 365 g / eq N-670: "Epiclon (registered trademark) N-670" manufactured by DIC Corporation; cresol novolac epoxy resin, epoxy equivalent weight 210 g / eq <Curing agent> 1,2DMZ: "Curezol (registered trademark) 1,2DMZ" manufactured by Shikoku Chemicals Corporation; 1,2-dimethylimidazole BRG-557: "BRG-557", manufactured by Aica Kogyo Co., Ltd.; phenolic novolac resin <Curing accelerator> C17Z: "Curezol (registered trademark) C17Z" manufactured by Shikoku Chemicals Corporation; 2-heptadecylimidazole <Flame retardant> FP-100: "Ravitor (registered trademark) FP-110", manufactured by Mitsui Fine Chemicals, Inc.; phosphazene flame retardant <Filling material> FB-105: "FB-105" manufactured by Denka Co., Ltd.; spherical fused silica, average particle size 12 μm SO-C2: "Admafine (registered trademark) SO-C2" manufactured by Admatechs Co., Ltd.; spherical fused silica, average particle size 0.5 μm DAW-07: "DAW-07", manufactured by Denka Co., Ltd.; spherical alumina, average particle size 8 μm <pedot pss> PEDOT / PSS: "CV10" manufactured by Kleba Corporation; 1.5% by weight aqueous solution (The formulations in the table are shown as solid content values after evaporation of water.) <Carbon nanotubes> CNT: "LUCAN (registered trademark) BT1003M" manufactured by LG Chemical Co., Ltd.; average fiber length 30 μm, average fiber diameter 20 nm

[0044] The average fiber length and average fiber diameter of carbon nanotubes were measured by measuring the fiber length and fiber diameter of 100 randomly selected particles in an image observed with a scanning electron microscope (SEM), and then calculating the number average.

[0045] [Evaluation method] Each of the resin compositions of the Examples and Comparative Examples was compression molded (at a temperature of 175°C and a pressure of 10 MPa) to prepare a sheet-like cured product sample (0.5 mm or 1.0 mm thick). The electromagnetic wave suppression ability and volume resistivity of each sample were measured and evaluated. Furthermore, for the resin compositions for semiconductor encapsulation materials (Examples 5 to 8 and Comparative Examples 5 to 8), the melt viscosity of the resin composition and the thermal expansion coefficient of the sample (thickness 1.0 mm) were also measured and evaluated. The various evaluation methods are shown below, and the evaluation results are shown in Tables 1 and 2.

[0046] (Electromagnetic wave suppression ability) A 0.5mm thick sample was placed between the high-frequency oscillator device and the receiving antenna, and electromagnetic waves (frequency 10GHz) were generated and the electromagnetic wave intensity was measured. The electromagnetic wave suppression ability [dB] was calculated from the ratio of this electromagnetic wave intensity to the electromagnetic wave intensity without the sample. The electromagnetic wave intensity was measured in accordance with the Transactions of the Institute of Electronics, Information and Communication Engineers, Vol. J97-B, No. 3, pp. 279-285. Electromagnetic wave suppression capability (10 GHz) of 3 dB or more is considered to be good.

[0047] (volume resistivity) The volume resistivity of a 1.0 mm thick sample was measured at 150°C in accordance with JIS K-6911:2006. Volume resistivity is 1.0×10 8 If the volume resistivity is 1.0×10 Ω·cm or more, the insulating properties of the cured product are considered to be good. 9 It may be 1.0×10 Ω·cm or more. 10 It may be Ω·cm or more.

[0048] (melt viscosity) The melt viscosity was measured using a flow tester (constant test force extrusion capillary rheometer "CFT-500C", manufactured by Shimadzu Corporation; die length 1.0 mm, die diameter 0.5 mm, temperature 160°C, test pressure 0.98 MPa). If the melt viscosity of the resin composition is 50 Pa·s or less, it can be said that the resin composition has good fluidity and is easy to handle as an encapsulating material. The melt viscosity may be 40 Pa·s or less, or may be 30 Pa·s or less.

[0049] (thermal expansion coefficient) The thermal expansion coefficient of a 1.0 mm thick sample was measured using a thermomechanical analysis (TMA) device (heating rate 10°C / min, measurement temperature range 25 to 60°C). A thermal expansion coefficient of 20 ppm / °C or less can be said to be sufficiently low.

[0050] [Table 1]

[0051] [Table 2]

[0052] As shown in the evaluation results in Table 1, it was found that the resin compositions for sheet-forming materials of Examples 1 to 4 gave cured products with good electromagnetic wave suppression ability and good insulating properties. Furthermore, as shown in the evaluation results in Table 2, it was confirmed that the resin compositions for semiconductor encapsulation materials of Examples 5 to 8 retain fluidity, have good electromagnetic wave suppression ability and insulating properties, and furthermore, produce cured products with low thermal expansion coefficients.< / pedot>

Claims

1. Comprising a composite of epoxy resin, poly(3,4-ethylenedioxythiophene) and poly(4-styrenesulfonic acid), An electromagnetic wave suppression resin composition having a poly(3,4-ethylenedioxythiophene) and poly(4-styrenesulfonic acid) composite content of 0.2 to 6.0 mass %.

2. 2. The electromagnetic wave suppressing resin composition according to claim 1, wherein the epoxy resin has a polyoxyalkylene structure.

3. The electromagnetic wave suppressing resin composition according to claim 1 or 2, further comprising a filler.

4. 4. The electromagnetic wave suppressing resin composition according to claim 3, wherein the filler content is 30.0 to 95.0 mass %.

5. 5. The electromagnetic wave suppressing resin composition according to claim 4, which is a sheet-forming material, and has a filler content of 30.0 to 90.0 mass %.

6. 5. The electromagnetic wave suppressing resin composition according to claim 4, which is a semiconductor encapsulation material, and has a filler content of 60.0 to 95.0 mass %.

7. A cured product of the electromagnetic wave suppression resin composition according to claim 1 or 2.

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