Thin film capacitor

Abstract

The invention provides a thin film capacitor. The thin film capacitor includes a dielectric layer and a conductive layer. The dielectric layer includes a polyimide and conductive particles. The polyimide includes ether linkages. The total content of the monomer units having ether linkages is 50 parts by weight to 100 parts by weight based on 100 parts by weight of the polyimide. The total content of the conductive particles is 10 parts by weight to 70 parts by weight based on 100 parts by weight of the dielectric layer. The conductive layer is disposed on a surface of the dielectric layer.

Description

Technical Field

[0001] The present invention relates to a film capacitor, and more particularly to a film capacitor with a double-layer structure. Background Art

[0002] Film capacitors are one of the most commonly used types of capacitors in electronic devices. Film capacitors have no polarity, so they can be used in alternating current (AC) and power applications. Film capacitors can hold a large charge for a longer period of time than other types of capacitors. This means that film capacitors can have a longer lifespan. In addition, film capacitors are stable, reliable, and have a lower cost than some other types of capacitors in the same application.

[0003] A typical film capacitor has a three-layer structure, in which a plastic film serves as a dielectric layer and two layers of metal foil are attached to the two sides of the plastic film as electrodes. Commonly used materials for plastic films include polypropylene (PP), polyphenylene sulfide (PPS), and polyethylene terephthalate (PET). The characteristics of film capacitors can be adjusted by using different types of plastic films. Generally speaking, film capacitors with PP, PPS, or PET dielectric layers are used in operating temperatures of -55°C to 125°C, and the dielectric constant is about 2 to 4. Summary of the invention

[0004] The present invention provides an improved film capacitor.

[0005] The film capacitor of the present invention comprises a dielectric layer and a conductive layer. The dielectric layer comprises polyimide and conductive particles. The polyimide comprises ether linkages. Based on 100 parts by weight of the polyimide, the total content of monomer units having ether linkages is 50 parts by weight to 100 parts by weight. Based on 100 parts by weight of the dielectric layer, the total content of the conductive particles is 10 parts by weight to 70 parts by weight. The conductive layer is disposed on a surface of the dielectric layer.

[0006] By using the above-mentioned dielectric layer including polyimide having ether linkage and conductive particles, the film capacitor of the present invention can have better characteristics and a simplified and thus thinner structure.

[0007] In order to better understand the above and other aspects of the present invention, embodiments are given below and described in detail with reference to the accompanying drawings: BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1A to Figure 1B is a schematic diagram of a film capacitor according to the present invention.

[0009] Description of Reference Numerals

[0010] 100: Film capacitor

[0011] 110: Dielectric layer

[0012] 112:Polyimide

[0013] 114: Conductive particles

[0014] 116: Dispersant

[0015] 120: Conductive layer DETAILED DESCRIPTION

[0016] The following will be described in more detail with reference to the accompanying drawings for various embodiments. The description and drawings are provided for illustration only and are not intended to be limiting. Spatial terms such as "upper", "lower", "left", "right", "front", "back", etc. can be used to simplify the description of the relationship between components. However, it should be understood that in addition to indicating the direction in the drawings, spatial terms should also include the direction of the items in different situations. For example, a component is originally located on another component, but if the item is turned upside down, the component will become located under the other component. In addition, for clarity, the components may not be drawn according to the actual scale. Some components and / or symbols may be omitted in some drawings. It is expected that the components and features in one embodiment can be advantageously incorporated into another embodiment without further description.

[0017] Please refer to Figure 1A to Figure 1B , which shows a thin film capacitor 100 according to the present invention. The thin film capacitor 100 includes a dielectric layer 110 and a conductive layer 120. The dielectric layer 110 includes a polyimide 112 (presented in a matrix) and conductive particles 114. The polyimide 112 includes ether linkages. Based on 100 parts by weight of the polyimide 112, the total content of monomer units having ether linkages is 50 parts by weight to 100 parts by weight. Based on 100 parts by weight of the dielectric layer 110, the total content of the conductive particles 114 is 10 parts by weight to 70 parts by weight. The conductive layer 120 is disposed on a surface of the dielectric layer 110.

[0018] The dielectric layer 110 uses a polyimide 112 as a matrix. The polyimide 112 can be synthesized from a diamine monomer and a dianhydride monomer in an organic solvent. In this case, the polyimide 112 may include a diamine monomer unit and a dianhydride monomer unit, wherein the diamine monomer unit and / or the dianhydride monomer unit include an ether linkage. The ether linkage may be contained in the main chain of the diamine monomer unit and / or the dianhydride monomer unit. In the synthesis of polyimide, the proportion of the monomer to its monomer unit is approximately the same, because an amine group and an anhydride functional group (anhydride group) react to generate an imide functional group (imide group) which only removes one water molecule (H2O). Therefore, the proportion of the monomer unit can be simply estimated from the proportion of the monomer. That is, when the total weight of the diamine monomers including ether linkages and the dianhydride monomers including ether linkages accounts for 50% to 100% of the total weight of all diamine monomers and dianhydride monomers used to form the polyimide 112, it can be regarded as that based on 100 parts by weight of the polyimide 112, the total content of the monomer units having ether linkages is 50 parts by weight to 100 parts by weight.

[0019] Specifically, the diamine monomer unit including an ether linkage may be a monomer unit formed from monomers represented by formula (1) or formula (2) independently of each other:

[0020] Formula (1)

[0021]

[0022] Formula (2)

[0023]

[0024] In formula (1), M1 and M2 are independently H, OR1, or R1, and R1 is C n F m H 2n+1-m , n is an integer from 1 to 8, and m is an integer from 0 to 17. In formula (2), M1 and M2 are independently H, OR1, or R1, and R1 is C n F m H 2n+1-m , n is an integer from 1 to 8, m is an integer from 0 to 17, and X is represented by any one of formulas (2-1) to (2-8):

[0025] Formula (2-1)

[0026]

[0027] Formula (2-2)

[0028]

[0029] Formula (2-3)

[0030]

[0031] Formula (2-4)

[0032]

[0033] Formula (2-5)

[0034]

[0035] Formula (2-6)

[0036]

[0037] Formula (2-7)

[0038]

[0039] Formula (2-8)

[0040]

[0041] In each of Formula (2-1) to Formula (2-8), M3 and M4 are independently H, OR1, or R1, and R1 is C n F m H 2n+1-m, n is an integer of 1 to 8, and m is an integer of 0 to 17. For example, the diamine monomer unit may include diaminodiphenyl ether represented by formula (1-I), formula (1-II), or formula (1-III), 4,4'-diamino-2-(trifluoromethyl)diphenyl ether represented by formula (1-IV), 4,4'-diamino-2-(trifluoromethyl)diphenyl ether represented by formula (1-V), 4,4'-diamino-2-(trifluoromethoxy)diphenyl ether represented by formula (1-VI), 4,4'-diamino-2,2'-bis(trifluoromethyl)diphenyl ether represented by formula (1-VI), ether), 4,4'-diamino-2,2'-bis(trifluoromethoxy)diphenyl ether represented by formula (1-VII), bis(4-aminophenoxy)benzene represented by formula (2-I) or formula (2-II), 1,3-bis(3-aminophenoxy)benzene represented by formula (2-III), 1,4-bis{4-amino-2-(trifluoromethyl)phenoxy}benzene represented by formula (2-IV), 1,4-bis(4-aminophenoxy)-2,5-di-tert-butylbenzene represented by formula (2-V), The following are examples of the compounds: 2,2-bis{4-(4-aminophenoxy)phenyl}propane (DTBAB), 2,2-bis{4-(4-aminophenoxy)phenyl}propane (2,2-bis{4-(4-aminophenoxy)phenyl}methane (2,2-bis{4-(4-aminophenoxy)phenyl}methane (2-VII), 2,2-bis{4-(4-aminophenoxy)phenyl}hexafluoropropane (2,2-bis{4-(4-aminophenoxy)phenyl}hexafluoropropane (2-IX))2-bis[4-{4-amino-2-(trifluoromethyl)phenoxy}phenyl]hexafluoropropane, 2,2-bis[4-{4-amino-2-(trifluoromethoxyl)phenoxy}phenyl]hexafluoropropane represented by formula (2-X), A monomer unit formed by at least one of 4,4'-bis(4-aminophenoxy)biphenyl represented by formula (2-XI), bis{4-(aminophenoxy)phenyl}sulfone represented by formula (2-XII) or formula (2-XIII), and bis{4-(4-aminophenoxy)phenyl}ketone represented by formula (2-XIV): Formula (1-I),

[0042]

[0043] Formula (1-II)

[0044]

[0045] Formula (1-III)

[0046]

[0047] Formula (1-IV)

[0048]

[0049] Formula (1-V)

[0050]

[0051] Formula (1-VI)

[0052]

[0053] Formula (1-VII)

[0054]

[0055] Formula (2-I)

[0056]

[0057] Formula (2-II)

[0058]

[0059] Formula (2-III)

[0060]

[0061] Formula (2-IV)

[0062]

[0063] Formula (2-V)

[0064]

[0065] Formula (2-VI)

[0066]

[0067] Formula (2-VII)

[0068]

[0069] Formula (2-VIII)

[0070]

[0071] Formula (2-IX)

[0072]

[0073] Formula (2-X)

[0074]

[0075] Formula (2-XI)

[0076]

[0077] Formula (2-XII)

[0078]

[0079] Formula (2-XIII)

[0080]

[0081] Formula (2-XIV)

[0082]

[0083] It is understood that the monomers represented by formula (1-I) to (1-VII) are monomers represented by formula (1), and the monomers represented by formula (2-I) to (2-XIV) are monomers represented by formula (2). The diamine monomer used to synthesize the polyimide 112 may include monomers represented by the above formula (1) and / or formula (2).

[0084] The dianhydride monomer unit including an ether linkage may be a monomer unit formed from monomers represented by formula (3) or formula (4) independently of each other:

[0085] Formula (3)

[0086]

[0087] Formula (4)

[0088]

[0089] In formula (3), D1 and D2 are independently H, OR2, or R2, and R2 is C n F m H 2n+1-m , n is an integer from 1 to 8, and m is an integer from 0 to 17. In formula (4), D1 and D2 are independently H, OR2, or R2, and R2 is C n F m H 2n+1-m , n is an integer from 1 to 8, m is an integer from 0 to 17, and Y is represented by any one of formulas (4-1) to (4-8):

[0090] Formula (4-1)

[0091]

[0092] Formula (4-2)

[0093]

[0094] Formula (4-3)

[0095]

[0096] Formula (4-4)

[0097]

[0098] Formula (4-5)

[0099]

[0100] Formula (4-6)

[0101]

[0102] Formula (4-7)

[0103]

[0104] Formula (4-8)

[0105]

[0106] In each of formula (4-1) to formula (4-8), D3 and D4 are independently H, OR2, or R2, and R2 is C n F m H 2n+1-m , n is an integer of 1 to 8, and m is an integer of 0 to 17. For example, the dianhydride monomer unit includes a monomer unit formed by at least one of oxydiphthalic anhydride (ODPA) represented by formula (3-I) or formula (3-II), oxydimethylphthalic anhydride represented by formula (3-III) or formula (3-IV), bisphenol A dianhydride represented by formula (4-I), tetramethyl bisphenol A dianhydride represented by formula (4-II), bisphenol F dianhydride represented by formula (4-III), and tetramethyl bisphenol F dianhydride represented by formula (4-IV):

[0107] Formula (3-I)

[0108]

[0109] Formula (3-II)

[0110]

[0111] Formula (3-III)

[0112]

[0113] Formula (3-IV)

[0114]

[0115] Formula (4-I)

[0116]

[0117] Formula (4-II)

[0118]

[0119] Formula (4-III)

[0120]

[0121] Formula (4-IV)

[0122]

[0123] Among them, the monomer represented by formula (3-I) is generally called 4-4'-oxybiphenyl anhydride (4-4'-ODPA), and the monomer represented by formula (3-II) is generally called 3-4'-oxybiphenyl anhydride (3-4'-ODPA). It can be understood that the monomers represented by formula (3-I) to formula (3-IV) are monomers represented by formula (3), and the monomer represented by formula (4-IV) is a monomer represented by formula (4). The dianhydride monomer used to synthesize polyimide 112 can include monomers represented by the above formula (3) and / or formula (4).

[0124] It is understood that the monomers used to synthesize the polyimide 112 can be mixed. That is, the diamine monomer unit of the polyimide 112 can be derived from only one of the monomers represented by formula (1), from multiple monomers represented by formula (1), from only one of the monomers represented by formula (2), from multiple monomers represented by formula (2), or from one or more monomers represented by formula (1) and one or more monomers represented by formula (2). Similarly, the dianhydride monomer unit of the polyimide 112 can be derived from only one of the monomers represented by formula (3), from multiple monomers represented by formula (3), from only one of the monomers represented by formula (4), from multiple monomers represented by formula (4), or from one or more monomers represented by formula (3) and one or more monomers represented by formula (4). Furthermore, the polyimide 112 may have only one diamine monomer unit and only one dianhydride monomer unit, only one diamine monomer unit but multiple dianhydride monomer units, multiple diamine monomer units but only one dianhydride monomer unit, or multiple diamine monomer units and multiple dianhydride monomer units at the same time. It is understood that, without affecting the effect of the present invention, the polyimide 112 may include other types of diamine monomer units (including diamine monomer units without ether linkages), other types of dianhydride monomer units (including dianhydride monomer units without ether linkages), or even monomer units that are not diamine monomer units or dianhydride monomer units. Furthermore, without affecting the effect of the present invention, the other components mentioned in the present invention may also be mixed.

[0125] The organic solvent used to synthesize the polyimide 112 may include at least one of N-methyl-2-pyrrolidone (NMP), N,N-dimethylacetamide (DMAC), 1,3-dimethyl-2-imidazolidinone (DMI), N,N-dimethylformamide (DMF), sulfolane, γ-butyrolactone (GBL), dimethyl sulfoxide (DMSO), m-cresol, hexamethylphosphoramide (HMPA), cyclopentanone (CPN), cyclohexanone (CHN), diglyme, and triglyme, but is not limited thereto.

[0126] Conductive particles 114 are dispersed in the matrix of polyimide 112. Conductive particles 114 may include at least one of gold, silver, copper, iron, cobalt, nickel, aluminum, manganese, zinc, lead, magnesium, titanium, carbon black, and graphene, but are not limited thereto. The particle size of conductive particles 114 is, for example, 10 nm to 5 μm. Different conductive particles 114 may have different particle sizes, and the particle size distribution within the range of 10 nm to 5 μm may be adjusted.

[0127] The dielectric layer 110 can be obtained by dispersing the conductive particles 114 into the polyimide 112 in an organic solvent. In some embodiments, a dispersant can be further used. The conductive particles 114, the organic solvent, and the dispersant are first mixed uniformly, and then the polyimide solution is added and mixed uniformly to form a dielectric layer coating. The dielectric layer coating is applied, heated and dried, and then cooled to room temperature to obtain the dielectric layer 110. The organic solvent may include at least one of N-methyl-2-pyrrolidone (NMP), N,N-dimethylacetamide (DMAC), 1,3-dimethyl-2-imidazolidinone (DMI), N,N-dimethylformamide (DMF), sulfolane, γ-butyrolactone (GBL), dimethyl sulfoxide (DMSO), m-cresol, hexamethylphosphoramide (HMPA), cyclopentanone (CPN), cyclohexanone (CHN), diglyme, and triglyme, but is not limited thereto.

[0128] In the case where a dispersant is used in the preparation of the dielectric layer 110, such as Figure 1B As shown, the dielectric layer 110 may further include a dispersant 116 , and the conductive particles 114 may be dispersed in the matrix of the polyimide 112 via the dispersant 116 .

[0129] The dispersant 116 may include a coupling agent and an organic dispersant. The coupling agent may include aluminum monostearate, aluminum distearate, isopropoxyaluminum distearate, aluminum tristearate, titanium tris(dodecylbenzenesulfonate) isopropoxide, titanium triisostearoyl isopropoxide, isopropyltristearyl titanate, tetrabutyl orthotitanate tetramer, (3-aminopropyl)triethoxysilane, (3-glycidyloxypropyl)trimethoxysilane, 3-(trimethoxysilyl)propyl methacrylate, At least one of 3-isocyanatopropyl triethoxysilane, 3-isocyanatopropyl triethoxysilane, trimethoxyphenylsilane, N-phenyl-3-aminopropyltrimethoxysilane, 3-acryloxypropyltrimethoxysilane, and p-styryltrimethoxysilane, but is not limited thereto.

[0130] The organic dispersant may include at least one of polyoxyethylene lauryl ether phosphate, polyethylene, polypropylene, polystyrene, polyvinyl alcohol, polyethylene glycol, tris(2-ethylhexyl)phosphate, cellulose and its derivatives, polyacrylamide, and polyethylene glycol distearate, but is not limited thereto. The cellulose or cellulose derivatives may be, for example, methylcellulose, ethylcellulose, hydroxypropyl cellulose, hydroxypropylmethyl cellulose, or carboxymethylcellulose, but is not limited thereto.

[0131] The polyimide 112 may be a polyimide soluble in an organic solvent, which is softer than a polyimide insoluble in an organic solvent and is suitable for forming a coil.

[0132] According to the present invention, the main materials of the dielectric layer 110 are polyimide with ether linkage and conductive particles. Compared with PP, PPS, and PET, polyimide with ether linkage has better heat resistance, frost resistance, dielectric properties, mechanical properties, and processability. For example, since polyimide with ether linkage has better heat resistance, the upper limit of the operating temperature can be further increased by using the dielectric layer 110 of the present invention. The film capacitor 100 of the present invention can be used at an operating temperature of -55°C to 200°C. The addition of conductive particles can increase the dielectric constant (dielectric constant, Dk) of the dielectric layer, increase the storage capacity of the film capacitor, and facilitate the miniaturization of the film capacitor. The dielectric constant of the dielectric layer 110 of the present invention is greater than or equal to 6, and in a preferred case can be increased to greater than or equal to 8. In addition, the addition of a dispersant can reduce dielectric loss (dielectric loss, Df). The dielectric loss of the dielectric layer 110 of the present invention is less than 1.

[0133] The conductive layer 120 is disposed on a surface of the dielectric layer 110. Figure 1A and Figure 1BIn the embodiment, the conductive layer 120 is disposed above the dielectric layer 110. When the coil is formed, the conductive layer 120 may be located outside the dielectric layer 110. However, it is understood that the conductive layer 120 may also be disposed below the dielectric layer 110. In this case, the conductive layer 120 may be disposed below the dielectric layer 110. Figure 1A In the rolled form shown, the conductive layer 120 may be located inside the dielectric layer 110 .

[0134] Due to the improved electrical properties of the dielectric layer 110, the film capacitor 100 of the present invention can be formed into a double-layered coil of the dielectric layer 110 and the conductive layer 120 without a third layer. With a simplified structure, the film capacitor can become thinner, which is also conducive to miniaturization of the film capacitor.

[0135] In order to help understand the present invention, more specific examples and comparative examples are provided below for illustration.

[0136] [Synthesis of polyimide]

[0137] According to the ratios of Synthesis Examples 1 to 4 listed in Table 1, m-cresol (CAS: 108-39-4) solvent, 4,4'-methylenebis(2-methylaniline) (MDA, CAS: 838-88-0, diamine monomer without ether linkage), 3,4'-diaminodiphenylmethane (DADPM, CAS: 108-39-4) solvent, 4,4'-methylenebis(2-methylaniline) (CAS: 838-88-0, diamine monomer without ether linkage), ethane, CAS: 19430-83-2, diamine monomers without ether linkages), 1,4-bis(4-aminophenoxy)-2,5-di-t-butylbenzene (DTBAB, 1,4-bis(4-aminophenoxy)-2,5-di-t-butylbenzene, CAS: 189344-59-0, diamine monomers with ether linkages in the main chain), 3,4'-diphthalic anhydride (a-BPDA, 3,4'-biphthalic anhydride, CAS: 36978-41-3, dianhydride monomers without ether linkages), diphenyl sulfide dianhydride (TPDA, 4,4'-bis(phthalic anhydride) sulfide, CAS: 25884-43-9, dianhydride monomers without ether linkages), and 3,4'-oxydiphthalic anhydride (3,4'-ODPA, 3,4'-oxydiphthalic anhydride anhydride, CAS: 50662-95-8, dianhydride monomer containing ether linkage in the main chain) is added to a four-mouth reaction bottle. Then, the four-mouth reaction bottle is assembled with a thermometer, a condenser, a Dean-Stark water separator, a stirring rod, a titration funnel, and a heater. Nitrogen is introduced, and the nitrogen flow rate is 500cc / min. The stirring rate is maintained at 100rpm. Then, isoquinoline (CAS: 119-65-3) catalyst is added to the four-mouth reaction bottle through a titration funnel, and then the temperature of the reaction mixture is increased to 200°C, and the reaction is reacted for 6 hours, and then the heating is stopped to cool the reaction mixture. Pour it out to obtain the product PI-A, PI-B, PI-C, and PI-D polyimide solutions, corresponding to Synthesis Example 1, Synthesis Example 2, Synthesis Example 3, and Synthesis Example 4, respectively. The total weight and solid content of PI-A, PI-B, PI-C, and PI-D polyimide solutions are also listed in Table 1.

[0138] Table 1

[0139]

[0140] [Influence of the content of monomer / monomer unit having ether linkage]

[0141] [Preparation of dielectric layer coating]

[0142] 5 g of trimethoxyphenylsilane (CAS: 2996-92-1) and 45 g of m-cresol solvent were mixed to form a 10 wt % trimethoxyphenylsilane solution. Alternatively, 5 g of tris(2-ethylhexyl)phosphate (CAS: 78-42-2) and 45 g of m-cresol solvent were mixed to form a 10 wt % tris(2-ethylhexyl)phosphate solution. Silver powder, m-cresol, and 10 wt % trimethoxyphenylsilane solution or tris(2-ethylhexyl)phosphate solution were mixed according to the proportions of Preparation Examples 1 to 4 listed in Table 2, and the mixture was stirred at room temperature for 24 h, with the stirring rate maintained at 200 rpm. Then, PI-A, PI-B, PI-C, or PI-D polyimide solution was added and stirred for 1 hour to obtain dielectric layer coating a, dielectric layer coating b, dielectric layer coating c, and dielectric layer coating d, which correspond to Preparation Example 1, Preparation Example 2, Preparation Example 3, and Preparation Example 4, respectively. In short, Preparation Examples 1 to 4 are to prepare dielectric layer coatings a to d using the above-synthesized PI-A to PI-D polyimide solutions. The total weight, solid content, silver powder content, and viscosity at 25°C of the dielectric layer coating are also listed in Table 2. The viscosity measurement method of the dielectric layer coating is to use a viscometer (Viscolead one, Fungilab) according to the method specified in JIS K 5400:1990 to measure the viscosity of the dielectric layer coatings a to d respectively, the temperature is controlled at 25°C, and the viscosity unit is cP.

[0143] Table 2

[0144]

[0145]

[0146] [Fabrication of Dielectric Layer]

[0147] Using a doctor blade with a gap of 50 μm and a width of 150 mm and a translation coater (ZAA2300, ZEHNTNER), dielectric layer coatings a to d were respectively coated on the untreated surface of PET (thickness 50 μm, BD216, Nan Ya). It was placed in an oven at 150°C for drying for 30 minutes, then removed from the oven and left to cool to room temperature to obtain a dielectric layer with PET as the substrate. In short, dielectric layer A, dielectric layer B, dielectric layer C, and dielectric layer D were prepared using the above-prepared dielectric layer coating a, dielectric layer coating b, dielectric layer coating c, and dielectric layer coating d, respectively.

[0148] [Testing and measurement of dielectric layers]

[0149] [Film-forming properties]

[0150] Visual inspection was performed to determine whether the dielectric layer formed a continuous film on the PET to determine the film-forming property of the dielectric layer after the PET was dried.

[0151] [Appearance integrity]

[0152] The dried dielectric layer is peeled off from the PET, and the dielectric layer is visually inspected to see if it is intact and without damage, so as to determine the appearance integrity of the dried dielectric layer after being peeled off from the PET.

[0153] [Average thickness]

[0154] The thickness of the dielectric layer peeled from the PET was measured using a micrometer (Micrometer, MITUTOYO IP65) at 10 points, and the average value of the 10 points was used as the average thickness of the dielectric layer.

[0155] [Average dielectric constant and dielectric loss]

[0156] Prepare two circular metal sheets of the same shape and size. The center of the metal sheet is a circular hollow. The diameter and thickness of the metal sheet are 18mm and 1mm respectively, and the diameter of the circular hollow is 8mm. Cut the dielectric layer into a square of about 18mm×18mm, and then sandwich the square dielectric layer between the above two circular metal sheets and align the above two circular metal sheets up and down so that the dielectric layer exposes a circular area of ​​8mm in diameter in the hollow position of the two metal sheets. Then fix the two metal sheets with tape so that the two metal sheets and the dielectric layer will not shift. Use a sputter coater (sputter coater, AGB7340, Agar Scientific) and a gold target to gold-plate the two sides of the above exposed circular area of ​​the dielectric layer so that the exposed two-sided dielectric layer surface is completely covered with gold. The gold plating conditions are vacuum degree less than 0.2mbar, current 35mA, and sputtering time 40s. Then, the two circular metal sheets are disassembled to take out the dielectric layer, thus completing the preparation of the gold-plated dielectric layer test piece for measuring the dielectric constant and dielectric loss.

[0157] The above-mentioned gold-plated dielectric layer test piece was measured using a dielectric tester (6630-1, Yihe) and a FX-000C12 measuring fixture. The measuring position of the gold-plated dielectric layer test piece was the circular area of ​​the gold-plated surface, and the measuring frequency was 100 Hz.

[0158] Two more gold-plated dielectric layer test pieces are made in the same way and the dielectric constant and dielectric loss of the gold-plated dielectric layer test pieces are measured. The average of the measured values ​​of the three test pieces is the average dielectric constant and average dielectric loss of the dielectric layer.

[0159] [Examples and Comparative Examples]

[0160] Example 1, Example 2, Example 3, and Comparative Example 1 respectively prepare dielectric layer A, dielectric layer B, dielectric layer C, and dielectric layer D, and test and measure their properties according to the above method, including the film-forming property of the dielectric layer after drying on PET, the appearance integrity of the dried dielectric layer after peeling off from PET, the average thickness of the dielectric layer, the average dielectric constant (Dk) and the average dielectric loss (Df) of the dielectric layer at 100 Hz. The test and measurement results are listed in Table 3.

[0161] Table 3

[0162]

[0163] The results of Example 1 show that dielectric layer A can form a continuous film after drying on PET, and the dried dielectric layer can be peeled off from PET intactly. This is because the main chain structure of the monomers of polyimide includes ether linkages, accounting for 53.2%, so the structure of dielectric layer A is tougher. The results of Examples 2 and 3 are similar to those of Example 1.

[0164] The results of Comparative Example 1 show that the dielectric layer D is not completely peeled off from the PET. This is because the main chain structure of the monomers of polyimide includes only 42.3% of the monomers with ether linkages, so the structure of the dielectric layer D is relatively rigid.

[0165] In general, the more ether-linked components in the structure of polyimide, the better the toughness of the polyimide, the more suitable it is for making coils and the less likely it is to crack. Correspondingly, the more the total content of diamine monomer units (with ether linkages) and dianhydride monomer units in the polyimide, the more suitable the polyimide is as the matrix of the film capacitor.

[0166] [Effect of conductive particles]

[0167] [Preparation of dielectric layer coating]

[0168] In the same manner as the above-mentioned dielectric coating, dielectric coatings e to i were prepared using PI-C polyimide solution according to the proportions of Preparation Examples 5 to 9 listed in Table 4. The total weight, solid content, content of silver powder, and viscosity at 25° C. of the dielectric coating are also listed in Table 4.

[0169] Table 4

[0170]

[0171] [Fabrication of Dielectric Layer]

[0172] In the same manner as the above-mentioned dielectric layer manufacturing method, dielectric layers E to I are manufactured respectively using dielectric layer coatings e to i.

[0173] [Testing and measurement of dielectric layers]

[0174] Dielectric layers E to I are tested and measured in the same manner as the above-mentioned dielectric layers.

[0175] [Windability]

[0176] The rollability of dielectric layers E to I was tested. First, each dielectric layer E to I was cut into a square of approximately 30 mm × 30 mm. The square dielectric layer was rolled into a roll shape by hand, with the length of the roll shape and the cross-sectional diameter of the roll bar being approximately 30 mm and approximately 5 mm, respectively. Then, the roll shape was loosened to restore it to its original square shape, and the square dielectric layer was visually inspected for cracks.

[0177] [Examples and Comparative Examples]

[0178] Example 4, Example 5, Example 6, and Comparative Examples 2, 3, and 4 respectively prepare dielectric layer C, dielectric layer E, dielectric layer F, dielectric layer G, dielectric layer H, and dielectric layer I, and test and measure their properties according to the above method, including the film-forming property of the dielectric layer after drying on PET, the appearance integrity of the dried dielectric layer after peeling from PET, the average thickness of the dielectric layer, the average dielectric constant (Dk) and average dielectric loss (Df) of the dielectric layer at 100 Hz, and windability. The test and measurement results are listed in Table 5.

[0179] Table 5

[0180]

[0181]

[0182] The results of Examples 4, 5, and 6 show that dielectric layers C, E, and F are suitable for film capacitors. In terms of mechanical properties, dielectric layers C, E, and F can form continuous films after drying, can be peeled off from PET intactly without damage, and can be wound without cracks. In terms of electrical properties, Dk≧8 and Df<1 of dielectric layers C, E, and F. This is because the monomers of the polyimide of dielectric layers C, E, and F have a main chain structure including ether linkages, which accounts for 100%, and the silver powder content accounts for 10 to 70%.

[0183] The results of Comparative Example 2 show that the silver powder content of dielectric layer G exceeds 70%, so the film is brittle, cannot be completely peeled off from PET, and cracks are generated during winding.

[0184] The result of Comparative Example 3 shows that the silver powder content of the dielectric layer H is less than 10%, so Dk<6.

[0185] [Feasibility of roll-type film capacitors]

[0186] [Manufacturing of roll-type film capacitors]

[0187] A 30mm×30mm long × 30mm wide dielectric layer (thickness about 10μm) and a 30mm×30mm long × 30mm wide copper foil (thickness 20μm, MW-G, Taiwan copper foil) are stacked together, and then rolled into a roll with the dielectric layer as the core to obtain a roll-shaped film capacitor.

[0188] [Testing of Roll-type Film Capacitors]

[0189] Place the roll-shaped film capacitor in a 300℃ hot air circulation oven and heat for 30 minutes, then remove it from the oven and let it cool to room temperature. Then, open the roll shape of the roll-shaped film capacitor by hand and visually inspect the bonding properties of the dielectric layer and copper foil.

[0190] [Examples and Comparative Examples]

[0191] Examples 7, 8, 9 and Comparative Example 5 are roll-shaped film capacitors made of dielectric layers A, B, C, and D, respectively, and their properties are tested in the above manner.

[0192] Examples 7, 8, 9 and Comparative Example 5 are used to test the feasibility of making a roll-shaped film capacitor with a dielectric layer, and their properties are tested and measured in the above manner. The test results are listed in Table 6.

[0193] Table 6

[0194]

[0195] The results of Examples 7, 8, and 9 show that the dielectric layers of the roll-shaped film capacitors A, B, and C can all adhere to copper foil. This is because the main chain structure of the polyimide monomers of the dielectric layers A, B, and C includes ether linkages accounting for 50-100%, so the dielectric layer structure is relatively soft and has good adhesion at 300°C.

[0196] The results of Comparative Example 5 show that the dielectric layer of the roll-shaped film capacitor D does not adhere to the copper foil. This is because the main chain structure of the polyimide monomer in the dielectric layer D includes only 42.3% of the ether linkage, so the structure of the polyimide is relatively rigid, making it difficult for the dielectric layer D to soften at 300° C. to improve adhesion.

[0197] The results of Examples 1 to 9 can prove that when the dielectric layer includes polyimide and conductive particles, the polyimide includes ether linkages, and the total content of monomer units with ether linkages is 50 to 100 parts by weight based on 100 parts by weight of the polyimide, and the total content of the conductive particles is 10 to 70 parts by weight based on 100 parts by weight of the dielectric layer, the dielectric layer has good toughness, and can improve the heat resistance, antifreeze, winding, mechanical, processing and other properties of the dielectric layer, and the dielectric constant of the dielectric layer can reach more than 6, and the dielectric loss can be less than 1. In addition, the dielectric layer can be made into a roll-shaped film capacitor with a conductive layer (such as copper foil), which improves the storage capacity of the roll-shaped film capacitor and is conducive to the miniaturization of the roll-shaped film capacitor.

[0198] In summary, although the present invention has been disclosed by way of embodiments, it is not intended to limit the present invention. A person skilled in the art of the present invention may make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be determined by the following claims.

Claims

1. A film capacitor, characterized in that: include: a dielectric layer comprising a polyimide and conductive particles, the polyimide comprising ether linkages, wherein the total content of monomer units having the ether linkages is 50 to 100 parts by weight based on 100 parts by weight of the polyimide, and wherein the total content of the conductive particles is 10 to 70 parts by weight based on 100 parts by weight of the dielectric layer; and The conductive layer is disposed on a surface of the dielectric layer.

2. The film capacitor according to claim 1, wherein: The polyimide includes a diamine monomer unit and a dianhydride monomer unit, and the diamine monomer unit and / or the dianhydride monomer unit include the ether linkage.

3. The film capacitor according to claim 2, characterized in that: The diamine monomer units including the ether linkage are monomer units independently formed from monomers represented by formula (1) or formula (2): Formula (1) Formula (2) Wherein, in formula (1), M1 and M2 are independently H, OR1, or R1, and R1 is C n F m H 2n+1-m , n is an integer from 1 to 8, and m is an integer from 0 to 17; and Wherein, in formula (2), M1 and M2 are independently H, OR1, or R1, and R1 is C n F m H 2n+1-m , n is an integer from 1 to 8, m is an integer from 0 to 17, and X is represented by any one of formulas (2-1) to (2-8): Formula (2-1) Formula (2-2) Formula (2-3) Formula (2-4) Formula (2-5) Formula (2-6) Formula (2-7) Formula (2-8) Wherein, in each of Formula (2-1) to Formula (2-8), M3 and M4 are independently H, OR1, or R1, and R1 is C n F m H 2n+1-m , n is an integer from 1 to 8, and m is an integer from 0 to 17.

4. The film capacitor according to claim 2, characterized in that: The dianhydride monomer units including the ether linkage are monomer units independently formed from monomers represented by formula (3) or formula (4): Formula (3) Formula (4) Wherein, in formula (3), D1 and D2 are independently H, OR2, or R2, and R2 is C n F m H 2n+1-m , n is an integer from 1 to 8, and m is an integer from 0 to 17; and Wherein, in formula (4), D1 and D2 are independently H, OR2, or R2, and R2 is C n F m H 2n+1-m , n is an integer from 1 to 8, m is an integer from 0 to 17, and Y is represented by any one of formulas (4-1) to (4-8): Formula (4-1) Formula (4-2) Formula (4-3) Formula (4-4) Formula (4-5) Formula (4-6) Formula (4-7) Formula (4-8) Wherein, in each of Formula (4-1) to Formula (4-8), D3 and D4 are independently H, OR2, or R2, and R2 is C n F m H 2n+1-m , n is an integer from 1 to 8, and m is an integer from 0 to 17.

5. The film capacitor according to claim 2, wherein: The ether linkage is contained in the main chain of the diamine monomer unit and / or the dianhydride monomer unit.

6. The film capacitor according to claim 2, wherein: The diamine monomer unit comprises diaminodiphenyl ether, 4,4'-diamino-2-(trifluoromethyl)diphenyl ether, 4,4'-diamino-2-(trifluoromethoxy)diphenyl ether, 4,4'-diamino-2-(trifluoromethoxy)diphenyl ether, 4,4'-diamino-2,2'-bis(trifluoromethyl)diphenyl ether, 4,4'-diamino-2,2'-bis(trifluoromethyl)diphenyl ether, 4,4'-diamino-2,2'-bis(trifluoromethoxy)diphenyl ether, ether), bis(4-aminophenoxy)benzene, 1,3-bis(3-aminophenoxy)benzene, 1,4-bis{4-amino-2-(trifluoromethyl)phenoxy}benzene, 1,4-bis{4-amino-2-(trifluoromethyl)phenoxy}benzene, 1,4-bis(4-aminophenoxy)-2,5-di-t-butylbenzene, 2,2-bis{4-(4-aminophenoxy)phenyl}propane yl}propane), 2,2-bis{4-(4-aminophenoxy)phenyl}methane, 2,2-bis{4-(4-aminophenoxy)phenyl}hexafluoropropane, 2,2-bis[4-{4-amino-2-(trifluoromethyl)phenoxy}phenyl]hexafluoropropane, 2,2-bis[4-{4-amino-2-(trifluoromethyl)phenoxy}phenyl]hexafluoropropane,The dianhydride monomer unit comprises a monomer unit formed by at least one of oxydiphthalic anhydride, oxydimethylphthalic anhydride, bisphenol A dianhydride, tetramethyl bisphenol A dianhydride, bisphenol F dianhydride, and tetramethyl bisphenol F dianhydride. dianhydride) in the monomer unit.

7. The film capacitor according to claim 1, wherein: The polyimide is a polyimide soluble in an organic solvent.

8. The film capacitor according to claim 1, wherein: The conductive particles include at least one of gold, silver, copper, iron, cobalt, nickel, aluminum, manganese, zinc, lead, magnesium, titanium, carbon black, and graphene, and the particle size of the conductive particles is 10 nm to 5 μm.

9. The film capacitor according to claim 1, wherein: The dielectric layer further includes a dispersant, and the conductive particles are dispersed in the matrix of the polyimide through the dispersant.

10. The film capacitor according to claim 9, characterized in that The dispersant includes a coupling agent and an organic dispersant.

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