Curable composition, electronic component, and circuit board

Abstract

A curable composition which is for forming an electronic component, or for forming a circuit board, according to one aspect of the present disclosure comprises: at least one additive selected from the group consisting of rosin and a derivative thereof; a curable compound; and a filler.

Description

Curable composition, electronic component, and circuit board

[0001] The present disclosure relates to curable compositions, electronic components, and circuit boards.

[0002] BACKGROUND ART Known electronic components include an element body containing a cured product of a curable composition and terminal electrodes that are conductors (for example, see Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2006-324490

[0004] To meet the demand for smaller, lighter, and thinner electronic devices, miniaturization is also required for the electronic components (passive components) mounted on electronic devices. As electronic components become smaller, the area of ​​terminal electrodes is becoming smaller. This reduces the contact area between the terminal electrodes and the element body, so from the perspective of improving strength, high adhesion between the element body and the terminal electrodes is desired.

[0005] Furthermore, in a circuit board having a substrate containing a cured product of a curable composition and a conductor pattern formed on the substrate, high adhesion between the substrate and the conductor is also desired from the viewpoint of improving strength.

[0006] In other words, the cured product of the curable composition is required to have high adhesiveness to the conductor.

[0007] One aspect of the present disclosure provides a curable composition that can achieve high adhesion to conductors. Another aspect of the present disclosure provides an electronic component and a circuit board that include a cured product of the curable composition.

[0008] The present disclosure provides the following curable compositions, electronic components, and circuit boards. [1] A curable composition for forming electronic components or circuit boards, comprising at least one additive selected from the group consisting of rosin and its derivatives, a curable compound, and a filler. [2] The curable composition according to [1], wherein the mass of the curable compound is represented by Mr, the mass of the filler is represented by Mp, the mass of the additive is represented by Ma, and Ma / (Mr+Mp+Ma) is 2% or more. [3] The curable composition according to [1] or [2], wherein the mass of the curable compound is represented by Mr, the mass of the filler is represented by Mp, the mass of the additive is represented by Ma, and Ma / (Mr+Mp+Ma) is 10% or less. [4] The curable composition according to any one of [1] to [3], wherein the mass of the curable compound is represented by Mr, the mass of the filler is represented by Mp, the mass of the additive is represented by Ma, and Mp / (Mr+Mp+Ma) is 3% or more and 85% or less. [5] The curable composition according to any one of [1] to [4], wherein the curable compound is thermosetting. [6] The curable composition according to any one of [1] to [5], wherein the curable compound comprises at least one member selected from the group consisting of bismaleimides and epoxy resins. [7] The curable composition according to any one of [1] to [6], wherein the additive comprises abietic acid. [8] The curable composition according to claim 7, wherein the content of abietic acid in the additive is 40% by mass or more, based on the total amount of the additives. [9] The curable composition according to any one of [1] to [8], wherein the filler comprises hollow particles.

[10] The curable composition according to any one of [1] to [9], wherein the filler comprises an insulating filler.

[11] The curable composition according to any one of [1] to

[10] , wherein the filler comprises inorganic oxide particles.

[12] The curable composition according to

[11] , wherein the inorganic oxide particles comprise La and Mn as constituent elements.

[13] An electronic component comprising: an element body comprising a cured product of the curable composition according to any one of [1] to

[12] ; and a pair of terminal electrodes arranged on the surface of the element body.

[14] The electronic component according to

[13] , wherein the electronic component is a high-frequency coil component and further comprises a coil portion composed of a wound conductor enclosed within the element body.

[15] The electronic component according to

[14] , wherein the coil portion and the pair of terminal electrodes are seamlessly integrated.

[16] A circuit board comprising: a substrate containing a cured product of the curable composition according to any one of [1] to

[12] ; and a conductor pattern formed on the substrate.

[0009] According to one aspect of the present disclosure, there is provided a curable composition capable of achieving high adhesion to a conductor. Also, according to another aspect of the present disclosure, there is provided an electronic component and a circuit board including a cured product of such a curable composition.

[0010] Fig. 1 is a perspective view of a coil component according to an example of an electronic component of an embodiment. Fig. 2 is a schematic cross-sectional view of the coil component shown in Fig. 1, the cross-section shown in Fig. 2 including a central axis of a coil portion and crossing a pair of terminal electrodes of the electronic component.

[0011] Hereinafter, preferred embodiments of the present disclosure will be described with reference to the drawings. In the drawings, like elements are designated by like reference numerals. The present disclosure is not limited to the following embodiments.

[0012] <Curable Composition> The curable composition according to this embodiment (hereinafter also simply referred to as "curable composition") will be described below. The curable composition is for forming electronic components or circuit boards. The curable composition contains at least one additive selected from the group consisting of rosin and its derivatives, a curable compound, and a filler. The curable composition can be cured, for example, by heating or light irradiation.

[0013] The curable composition contains an additive, a curable compound, and a filler. This allows for high adhesion to a conductor. A known method for improving adhesion between a conductor and an object to be bonded, such as an element or substrate, is to roughen the conductor surface to achieve an anchoring effect. Recently, the frequency of transmission signals on electronic circuits has increased, creating a demand for reduced transmission loss. One method for reducing transmission loss is smoothing the conductor. When an alternating current flows through a conductor, the higher the frequency, the higher the current density at the conductor surface, and the lower the current density with increasing distance from the conductor surface (closer to the center). Due to this skin effect, current concentrates on the conductor surface as the frequency increases, increasing the AC resistance of a conductor with a roughened surface. As a countermeasure, it is desirable to smooth the conductor surface, thereby reducing surface resistance and reducing loss. Because the curable composition can achieve high adhesion to a conductor, it can be used effectively even with a conductor having a smooth surface.

[0014] (Additives) Rosin is a natural mixture of resin acids extracted from plants of the Pinaceae family. Based on its production method, rosin is classified as gum rosin, tall oil rosin, or wood rosin. Examples of resin acids include abietic acid, neoabietic acid, palustric acid, dehydroabietic acid, levopimaric acid, pimaric acid, isopimaric acid, and sandaracopimaric acid.

[0015] The content of abietic acid may be, for example, 40% by mass or more, 50% by mass or more, 60% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass or more, or 95% by mass or more, based on the total amount of the additives. The content of abietic acid may be, for example, 90% by mass or less, 80% by mass or less, 70% by mass or less, or 60% by mass or less, based on the total amount of the additives.

[0016] The rosin may contain dihydroagatic acid, communic acid, and the like.

[0017] Examples of rosin derivatives include stabilized rosin (e.g., stabilized rosin obtained by disproportionating or hydrogenating rosin), polymerized rosin (e.g., rosin polymer, typically a dimer), modified rosin (e.g., unsaturated acid-modified rosin modified with an unsaturated acid such as maleic acid, fumaric acid, acrylic acid, or methacrylic acid), and esters thereof.

[0018] The additive is preferably rosin, which tends to provide even better adhesion between the resulting cured product and the conductor.

[0019] The rosin content may be 50% by mass or more, 60% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass or more, 95% by mass or more, or 100% by mass based on the total amount of additives.

[0020] The additives may be used alone or in combination of two or more.

[0021] (Curable Compound) The curable compound may be heat-curable or photo- (UV)-curable.

[0022] Examples of the curable compound include epoxy resin, polybismaleimide raw material, polyimide raw material, cyanate resin raw material, thermosetting polyphenylene ether raw material, and acrylic resin raw material. The curable compound is preferably an epoxy resin or polybismaleimide raw material. This tends to further improve the adhesion between the resulting cured product and the conductor.

[0023] Epoxy resins are compounds having a glycidyl group. Epoxy resins may be monofunctional, bifunctional, or polyfunctional. Epoxy resins may be monomeric compounds, or oligomeric or polymeric compounds having a plurality of specific monomer units.

[0024] When the curable compound contains an epoxy resin, the curable compound may contain a curing agent for the epoxy resin, such as an imidazole compound, a hydrazide compound, a boron trifluoride-amine complex, an acid anhydride compound, a polyamine compound, or a phenol compound (phenol resin).

[0025] The raw materials for polybismaleimides are bismaleimides and comonomers. Bismaleimides are compounds having an arbitrary organic group and two or more maleimide rings bonded to the organic group. Each of the pair of carbon atoms constituting the carbon-carbon double bond in the maleimide ring may be independently bonded to a monovalent atom selected from hydrogen atoms or halogen atoms, or a monovalent organic group. Any organic group of the bismaleimide may have a maleimide ring. When at least a portion of the arbitrary organic group has a maleimide ring, the bismaleimide and copolymer are polymerized three-dimensionally, which tends to improve the mechanical strength and heat resistance of the cured product. For example, the comonomer polymerizable with the bismaleimide may be at least one compound selected from the group consisting of vinyl compounds, allyl compounds, allylphenols, isocyanates, and aromatic amines.

[0026] Examples of raw materials for polybismaleimide include the following commercially available polybismaleimide raw material monomers, raw material oligomers, and raw material mixtures. The following BMI-2500, BMI-2560, BMI-3000J, BMI-6100, DMI-2550, and DMI-2555 are all polybismaleimide raw materials manufactured by Designer Molecules, Inc.

[0027] <BMI-2500> CAS Number: 2020378-57-6. Composition: Polycondensation product of 1,1'-(octahydro-1H-4,7-methanoindene-2,5-diyl)dimethanamine (a dimer diamine (limited to those with aminomethyl groups instead of carboxy groups) obtained by reducing and amminating cyclic dimer acids (mainly C=36) obtained as dimers of unsaturated fatty acids (C=18)) with furan-2,5-dione and 1H,3H-benzo[1,2-c:4,5-c']difuran-1,3,5,7-tetraone. (BMI-2500: Amines, C36-alkylenedi-, polymers with octahydro-4,7-methano-1H-indenedimethanamine and pyomellitic dianhydride, maleated.)

[0028] <BMI-2560> CAS Number: 2126832-79-7. Composition: Amines, C36-alkylenedi-, reaction products with maleic anhydride and 4,4'-methylenebis[2-methylcyclohexanamine]-5,5'-oxybis[1,3-isobenzofurandione]polymer.

[0029] <BMI-3000J> CAS number: 921213-77-6. Composition: (1,2-bis(octylmaleimide)-3-octyl-4-hexyl)cyclohexyl oligomer. (BMI-3000J: Amines, C36-alkylenedi-, polymers with pyromellitic dianhydride, maleated.)

[0030] <BMI-6100> CAS number: 2127116-97-4 Composition: Reaction products of 1,3-isobenzofurandione, polymer with 5,5'-[(1-methylethylidene)bis(4,1-phenyleneoxy)]bis-,4,4'-methylenebis[2,6-diethylbenzenamine], maleic anhydride and 4,4'-[(1-methylethylidene)bis(4,1-phenyleneoxy)]bis[benzeneamine]. (BMI-6100:1,3-Isobenzofurandione,5,5'-[(1-methylethylidene)bis(4,1-phenyleneoxy)]bis-,polymer with4,4'-methylenebis[2,6-diethylbenzenamine], reaction products with maleicanhydride and 4,4'-[(1-methylethylidene)bis(4,1-phenyleneoxy)]bis[benzenamine].)

[0031] <DMI-2550, DMI-2555> CAS number: 1911605-95-2. Composition: 1H-Pyrrole-2,5-dione, 1,1'-C36-alkylenebis-dicumyl peroxide. (DMI-2550 / DMI-2555: 1H-Pyrrole-2,5-dione, 1,1'-C36-alkylenebis-dicumyl peroxide)

[0032] The curable compounds may be used alone or in combination of two or more.

[0033] (Filler) Examples of filler materials include inorganic materials, organic materials, and metal materials. Inorganic materials include crystalline solid ceramics and amorphous solid glass. Generally, amorphous solid glass has higher mechanical strength than organic materials such as polymers. The amorphous solid glass may be at least one compound selected from the group consisting of alumina borosilicate glass, soda lime borosilicate glass, borosilicate glass, silica glass, soda lime glass, quartz glass, and organic glass. Examples of commercially available glass materials include CellSpheres (hollow particles containing alumina borosilicate glass) manufactured by Taiheiyo Cement Corporation, and 3M Glass Bubbles (hollow particles containing soda lime borosilicate glass) manufactured by 3M Japan Ltd.

[0034] Examples of ceramics include inorganic oxides. Constituent elements of inorganic oxides include, but are not limited to, La, Mn, Fe, Al, Ti, Cr, Zn, Mg, P, Cu, V, Ba, Co, Ca, Zr, Si, Bi, and Ni. Specific examples of fillers containing such constituent elements include La-Mn composite oxide particles, Fe-Al-Ti composite oxide particles, and Fe-Cr composite oxide particles. Using inorganic oxides as fillers can impart the properties of inorganic oxides to the cured product. Specific effects include opacification, discoloration concealment, high magnetic permeability, and low thermal expansion coefficient. Non-oxide ceramics may also be used as ceramics. Examples of non-oxide ceramics include boron nitride (BN) and aluminum nitride (AlN).

[0035] The organic material may be polystyrene, an acrylic resin such as polymethyl methacrylate, or a polycarbonate such as polydiethylene glycol bisallyl carbonate.

[0036] Examples of the metal material include Fe-based compounds, such as Fe, FeCo, FeNi, Fe—B, and Fe—Cr—B. By using such metal materials as fillers, it is possible to provide a cured product with high magnetic permeability, for example.

[0037] The filler may be solid particles or hollow particles. The filler is preferably hollow particles from the viewpoint of reducing the relative dielectric constant of the cured product. By lowering the dielectric constant of the cured product, the stray capacitance between conductor patterns formed on electronic components or circuit boards can be reduced, which is advantageous for improving the quality factor (Q value) and reducing transmission loss. Furthermore, hollow particles also enable weight reduction of electronic components and circuit boards. The hollow ratio of the filler (the ratio of the volume of voids in hollow particles) may be, for example, 50% by volume or more and 95% by volume or less, 55% by volume or more and 90% by volume or less, or 60% by volume or more and 80% by volume or less.

[0038] The filler preferably contains a combination of hollow glass particles and inorganic oxide particles, which makes it possible to provide a cured product that has a reduced dielectric constant and is endowed with the properties of inorganic oxides.

[0039] The mass ratio of the hollow glass particles to the inorganic oxide particles (hollow glass particles:inorganic oxide particles) may be 96.5:3.5 to 20:80.

[0040] The shape of the filler may be, for example, spherical, needle-like, fibrous, or plate-like.

[0041] The particle size (average particle size) of the filler may be 0.1 μm or more and 30 μm or less, 0.1 μm or more and 20 μm or less, or 0.1 μm or more and 10 μm or less. In the production of electronic components, the smaller the particle size of the filler, the easier it is to miniaturize the electronic components. However, the smaller the particle size of the filler, the more likely it is that the filler will aggregate during the production process of the electronic components, and the viscosity of the curable composition tends to increase.

[0042] The surface of the filler may be subjected to a surface treatment such as coating. By performing the surface treatment, the function and properties of the curable composition or the cured product can be improved. Examples of such surface treatments include silica coating, silane coupling agent treatment, and phosphoric acid treatment.

[0043] The filler may have insulating properties.

[0044] The fillers may be used alone or in combination of two or more.

[0045] When the mass of the curable compound is represented by Mr, the mass of the filler is represented by Mp, and the mass of the additive is represented by Ma, Ma / (Mr+Mp+Ma) is preferably 2% or more, more preferably 3% or more, and even more preferably 4% or more. Ma / (Mr+Mp+Ma) is preferably 10% or less, more preferably 7% or less, and even more preferably 6% or less. When Ma / (Mr+Mp+Ma) is in this range, the adhesion between the obtained cured product and the conductor tends to be even better.

[0046] Mp / (Mr+Mp+Ma) is preferably 3% or more, more preferably 5% or more, and even more preferably 20% or more. Furthermore, Mp / (Mr+Mp+Ma) is preferably 85% or less, more preferably 60% or less, and even more preferably 40% or less. This tends to further enhance the effect of adding the additive in improving the adhesion between the cured product and the conductor.

[0047] The total content of the curable compound, filler, and additives may be 20% by mass or more, 30% by mass or more, 40% by mass or more, 50% by mass or more, 60% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass or more, 95% by mass or more, or 100% by mass, based on the total amount of the curable composition.

[0048] The curable composition may contain a silane coupling agent (surfactant). When the curable composition contains a silane coupling agent, the cured product of the curable compound is likely to bond to the surface of the filler via the amphiphilic silane coupling agent during the manufacturing process of electronic components. As a result, the surface tension of the uncured curable compound is suppressed, air is less likely to be entrapped during the molding process, and the formation of voids in the cured product is likely to be suppressed. Furthermore, the cured product is likely to bond to the surface of the filler via the silane coupling agent, which increases the mechanical strength of the electronic components.

[0049] The curable composition may or may not contain an organic solvent. Examples of the organic solvent include ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone, alcohols such as methanol, ethanol, and isopropanol, and aromatic hydrocarbons such as toluene, xylene, and tetralin, but are not limited thereto, and other organic solvents may be used as needed.

[0050] <Electronic Component> The electronic component according to this embodiment includes an element body containing a cured product of the curable composition according to the above embodiment, and a pair of terminal electrodes arranged on the surface of the element body. An example of the electronic component according to this embodiment will be described below. Fig. 1 is a perspective view of a coil component according to an example of the electronic component according to this embodiment. Fig. 2 is a schematic cross-sectional view of the coil component shown in Fig. 1.

[0051] As shown in Figures 1 and 2, the coil component 1 includes a sealing portion 2 (element body), a coil portion 5, and a pair of terminal electrodes 3. The dimensions of the coil component 1 are not limited, but for example, the maximum and minimum widths of the coil component 1 may each be several hundred microns or more and several millimeters or less. For example, the coil component 1 may be a chip component of 3225 size (3.2 mm x 2.5 mm), 3216 size (3.2 mm x 1.6 mm), 2012 size (2.0 mm x 1.2 mm), 1608 size (1.6 mm x 0.8 mm), 1005 size (1.0 mm x 0.5 mm), 0603 size (0.6 mm x 0.3 mm), or 0402 size (0.4 mm x 0.2 mm). The coil component may be a high-frequency coil component. In the case of a high frequency coil component, the frequency band may be, for example, 1 GHz or more and 10 GHz or less, 2 GHz or more and 7 GHz or less, or 3 GHz or more and 7 GHz or less.

[0052] The coil portion 5 is composed of a wound conductor. The number of windings (turns) of the coil portion 5 is not limited. The entire coil portion 5 is sealed (embedded) in the sealing portion 2. However, the ends of the coil portion 5 connected to the terminal electrodes 3 (tips of the lead portions 5a and 5b) do not have to be sealed (embedded) in the sealing portion 2. The coil portion 5 is an air-core coil before being sealed in the sealing portion 2, but the inside of the coil portion 5 sealed in the sealing portion 2 is filled with the sealing portion 2. The shape of the sealing portion 2 is not limited, but the sealing portion 2 shown in Figures 1 and 2 is a rectangular parallelepiped. The sealing portion 2 has opposing first and second end faces, with one terminal electrode 3 covering the first end face and the other terminal electrode 3 covering the second end face. One end of the coil portion 5 (lead portion 5a) is electrically connected to one terminal electrode 3, and the other end of the coil portion 5 (lead portion 5b) is electrically connected to the other terminal electrode 3.

[0053] The structure of the coil component 1 is not limited to the structure shown in Figures 1 and 2. For example, the pair of terminal electrodes 3 may be formed within one side surface of the sealing portion 2, with one terminal electrode 3 being disposed at one end of the side surface and the other terminal electrode 3 being disposed at the other end of the same side surface. In other words, the pair of terminal electrodes 3 may be formed on one side surface of the sealing portion 2, and the pair of terminal electrodes 3 may be contained within the one side surface of the sealing portion 2.

[0054] The sealing portion 2 includes a cured product of the curable composition according to the embodiment. As shown in Fig. 2, a plurality of fillers 6 are dispersed in the cured product 4 of the curable compound. In this embodiment, the fillers 6 are particles containing voids (hollow particles), but the fillers 6 are not limited to hollow particles.

[0055] The content of the cured product of the curable composition according to the above embodiment may be 50% by mass or more, 60% by mass or more, 70% by mass or more, 80% by mass or more, 90% by mass or more, or 95% by mass or more, based on the total amount of the sealing portion 2.

[0056] The plurality of hollow particles may be dispersed approximately uniformly in the sealing portion 2. Even when the cured product 4 of the curable compound itself and the hollow particles themselves are transparent, the plurality of hollow particles in the sealing portion 2 tend to refract or scatter light (visible light) in the sealing portion 2. As a result, it becomes difficult for light to travel in a straight line in the sealing portion 2, and the sealing portion 2 and the entire coil component 1 can be made opaque.

[0057] The composition of the conductor constituting the coil portion 5 is not limited. For example, the conductor constituting the coil portion 5 may contain at least one metal element selected from the group consisting of copper (Cu), silver (Ag), nickel (Ni), and chromium (Cr). The conductor constituting the conductor wire may contain, for example, at least one selected from the group consisting of oxygen-free copper, tough pitch copper, phosphorus-deoxidized copper, and a copper-silver alloy. The surface of the conductor constituting the coil portion 5 may be covered with an insulating layer. The material of the insulating layer may, for example, contain at least one selected from the group consisting of polyurethane, polyvinyl formal, polyester, polyesterimide, polyamideimide, and polyimide.

[0058] The composition of the terminal electrode 3 is not limited. For example, the terminal electrode 3 may contain at least one metal element selected from the group consisting of silver (Ag), tin (Sn), copper (Cu), and nickel (Ni). The terminal electrode 3 may also be made of an alloy containing these metal elements. The terminal electrode 3 may also include multiple metal layers stacked on the surface of the sealing portion 2.

[0059] The coil portion is sealed with a cured product of the curable composition according to the above embodiment through a molding process. The molding process may be performed in the following manner. First, the coil portion 5 is placed in the cavity of a mold. Next, the curable composition (slurry or paste) is filled into the cavity. The curable composition filled in the mold is dried in a heated state, for example, in an oven, to obtain a semi-cured molded body. Next, the molded body is heated in a pressurized state using a vacuum molding machine, and the semi-cured molded body is cured. As a result, a sealed portion 2 is formed in which the coil portion 5 is sealed with the cured product of the curable composition.

[0060] When the curable composition does not contain a solvent, drying for semi-curing is not necessary. The curable composition filled in the mold is heated under pressure using a vacuum forming machine, whereby the coil portion 5 is sealed with the curable composition.

[0061] After the molding step, a pair of terminal electrodes 3 are formed on the surface of the sealing portion 2 to obtain the coil component 1. The terminal electrodes 3 may be formed by, for example, applying and baking a conductive paste, electrolytic plating, electroless plating, or a combination of these methods. Before forming the terminal electrodes 3, the sealing portion 2 may be machined to adjust the dimensions of the sealing portion 2.

[0062] While the coil component has been described above as an example of an electronic component according to the present embodiment, the electronic component of the present disclosure is not limited to the above example. For example, in the coil component 1 described above, the coil portion and the pair of terminal electrodes have a structure with a seam, but the coil component may have a structure in which the coil portion and the pair of terminal electrodes are seamlessly integrated. In other words, the coil portion and the pair of terminal electrodes may be conductors formed integrally.

[0063] Furthermore, for example, when the electronic component is a coil component, the coil component may be a multilayer coil component. In the case of a multilayer coil component, the coil portion may be formed by etching a copper foil or by sputtering, for example. Furthermore, the electronic component may be, for example, a capacitor.

[0064] <Circuit Board> The circuit board according to this embodiment will be described below. The circuit board according to this embodiment includes a substrate containing a cured product of the curable composition according to the above embodiment, and a conductor pattern formed on the substrate. The substrate contains a cured product of the layered curable composition. The substrate may consist only of a cured product of the layered curable composition, or may further contain a base material that serves to support the conductor pattern. In the circuit board according to this embodiment, the substrate contains a cured product of the curable composition according to the above embodiment. This results in excellent adhesion between the conductor and the substrate.

[0065] The substrate may be manufactured, for example, by applying the curable composition according to the above embodiment, which contains an organic solvent, onto a base material and then forming the composition into a sheet. Alternatively, the substrate may be manufactured, for example, by the following method. That is, a glass cloth impregnated with the curable composition according to the above embodiment is placed on the base material, and the curable composition is dried. The curable composition and the glass cloth are then heated and pressurized to cure the curable composition. This results in a substrate. The circuit board may be manufactured by forming a conductor pattern on a substrate containing a cured product of the curable composition according to the above embodiment. The method for forming the conductor pattern is not particularly limited.

[0066] The present disclosure is not necessarily limited to the above-described embodiments. Various modifications of the present disclosure are possible without departing from the spirit of the present disclosure, and these modifications are also included in the present disclosure.

[0067] The present disclosure will be described in detail with reference to the following examples and comparative examples, but the present disclosure is not limited to the following examples.

[0068] <Materials> The following materials were prepared.

[0069] (Curable compound) DMI-2555: trade name, bismaleimide monomer blend, manufactured by Designer Molecules Inc. Epoxy resin: a mixture of LCE-2615 (trade name, manufactured by Nippon Kayaku Co., Ltd.), solid phenolic resin MEH-7851-4H (trade name, manufactured by Meiwa Kasei Co., Ltd., phenol-biphenylene resin), and Curesol 2E4MZ (trade name, manufactured by Shikoku Kasei Co., Ltd., imidazole-based curing agent), with a blending ratio (LCE-2615: solid phenolic resin MEH-7851-4H: Curesol 2E4MZ) = 67:32:1 (mass ratio), and this mixture was dissolved in advance in a mixed solvent of acetone: methyl ethyl ketone = 1:1 (mass ratio) to a concentration of 40 mass%.

[0070] (Filler 1) Borosilicate glass hollow particles: manufactured by Taiheiyo Cement Corporation, trade name "CellSpheres-NF" SiO ２ Coated Fe—Si—Cr-based metal particles: Fe—Si—Cr-based soft magnetic metal powder (manufactured by Shinto Kogyo Co., Ltd., product name "FSC-2K") was prepared. ２ H ５ OH-NH ３ -H ２ The soft magnetic metal powder was dispersed in a mixed solution of SiO and subjected to hydrolysis treatment. ２ Coated Fe-Si-Cr metal particles were used. SiO ２ Coated Fe—Ni-based metal particles: soft magnetic powder (manufactured by Sigma-Aldrich, trade name “Iron Oxide Nickel (Fe ２ O ３ A C containing tetraethoxysilane (TEOS) was prepared. ２ H ５ OH-NH ３ -H ２ The soft magnetic powder was dispersed in a SiO 2 mixed solution and subjected to hydrolysis treatment. ２ The soft magnetic powder thus obtained was heat-treated at 300°C in a hydrogen gas stream to obtain a coated soft magnetic powder. ２The coated Fe—Ni-based metal particles used were: Polystyrene-based particles: solid particles, manufactured by Sekisui Plastics Co., Ltd., trade name "SBX-4" Cu—Zn—V—P—O-based composite oxide particles: manufactured by Misario Co., Ltd., trade name "PyroAdjuster (registered trademark)-C" Zn—Mg—P—O-based composite oxide particles: manufactured by Misario Co., Ltd., trade name "PyroAdjuster (registered trademark)-M"

[0071] (Filler 2) La—Mn—O based composite oxide particles: manufactured by Nakajima Sangyo Co., Ltd., trade name “GY209”, colorant Fe—Al—Ti—O based composite oxide particles: manufactured by TOMATEC Co., Ltd., trade name “42-554A”, colorant Fe—Cr—O based composite oxide particles: manufactured by TOMATEC Co., Ltd., trade name “42-707A”, colorant

[0072] (Additive) Rosin: Fujifilm Wako Pure Chemical Industries, Ltd.

[0073] <Preparation of curable compositions> (Examples 1 to 23, Comparative Examples 1 to 14) For each Example and Comparative Example, the materials shown in Table 1 were mixed to obtain the contents shown in Tables 1 to 3 to obtain a paste-like curable composition. The contents of the curable compounds shown in Tables 1 to 3 correspond to Mr / (Mr+Mp+Ma). The sum of the contents of Filler 1 and Filler 2 shown in Tables 1 to 3 corresponds to Mp / (Mr+Mp+Ma). The contents of the additives shown in Tables 1 to 3 correspond to Ma / (Mr+Mp+Ma).

[0074] <Measurement of Peel Strength> (Examples 1 to 23, Comparative Examples 1 to 14) A curable composition was applied to the smooth (glossy) side of an electrolytic copper foil (3EC-M2S-VLP manufactured by Mitsui Mining & Smelting Co., Ltd.) using a bar coater (coating gap: 200 μm) to obtain a coating. When the curable composition contained DMI-2555, the coating was temporarily cured by heating in the atmosphere (temperature: 150°C, holding time: 1 hour), and then fully cured by heating in a vacuum (temperature: 200°C, holding time: 1 hour). When the curable composition contained an epoxy resin, the coating was temporarily cured by heating in the atmosphere (temperature: 120°C, holding time: 1 hour), and then fully cured by heating in the atmosphere (temperature: 150°C, holding time: 1 hour). The copper foil sample thus prepared was cut to a width of 10 mm to obtain a test piece. The cut test pieces were fixed to a bakelite board with double-sided tape, and a peel test (pull-up angle: 90°, test speed: 50 mm / min) was performed to peel the copper foil from the cured product using a bond tester manufactured by XYZTEC Corp. The peel strength measurement results obtained are shown in Tables 1 to 3.

[0075] <Measurement of Lateral Push Shear Strength> (Examples 1, 3, 14-16, 18, Comparative Examples 1, 5, 9-12) Seamless terminal coils were fabricated. The terminal coils included a wound copper wire and first and second terminal electrodes made of copper provided on both ends of the copper wire. The coil portion and the first and second terminal electrodes were seamlessly integrated into a single structure. The seamless terminal coils were placed in a mold cavity. The curable compositions of each Example and Comparative Example were filled into the cavity. The seamless terminal coils and curable compositions in the cavity were heated (temperature: 150°C, holding time: 10 minutes) while applying pressure (pressure: 0.11 MPa) in the atmosphere to obtain a provisionally cured sheet in which the seamless terminal coils were sealed. This provisionally cured sheet was then heated in a vacuum (temperature: 200°C, holding time: 1 hour) to obtain a permanent cured sheet. Next, the first and second terminal electrodes were subjected to electroless Ni—Au plating, and then a rectangular shaped sealed portion (coil component) in which one coil portion was sealed was cut out from the sealing sheet. The dimensions of the coil component were 0.4 mm length x 0.2 mm width x 0.2 mm height. The coil component was reflow soldered onto a glass epoxy substrate to obtain a test sample. M705 solder (product name, manufactured by Senju Metal Industry Co., Ltd., Sn-3.0Ag-0.5Cu solder) was used as the solder.

[0076] The lateral push shear strength of the test samples was measured in accordance with JIS C62137-1-2:2010. A bond tester manufactured by XYZTEC was used as the measuring device. A glass epoxy substrate on which a coil component was mounted by reflow soldering was fixed to the measuring device with a jig. Next, pressure was applied to the coil component from the side at a rate of 0.1 mm / sec, and the force at which the coil component came off the substrate was measured as the lateral push shear strength. The measurement results of the lateral push shear strength obtained are shown in Tables 1 to 3.

[0077]

[0078]

[0079]

[0080] 1... coil component, 2... sealing portion, 3... terminal electrode, 4... cured product of curable compound, 5... coil portion, 6... filler.

Claims

1. A curable composition for forming electronic components or circuit boards, comprising at least one additive selected from the group consisting of rosin and its derivatives, a curable compound, and a filler.

2. The curable composition according to claim 1, wherein the mass of the curable compound is represented by Mr, the mass of the filler is represented by Mp, the mass of the additive is represented by Ma, and Ma / (Mr+Mp+Ma) is 2% or more.

3. The curable composition according to claim 1, wherein the mass of the curable compound is represented by Mr, the mass of the filler is represented by Mp, the mass of the additive is represented by Ma, and Ma / (Mr+Mp+Ma) is 10% or less.

4. The curable composition according to claim 1, wherein the mass of the curable compound is represented by Mr, the mass of the filler is represented by Mp, the mass of the additive is represented by Ma, and Mp / (Mr+Mp+Ma) is 3% or more and 85% or less.

5. The curable composition of claim 1, wherein the curable compound is thermosetting.

6. The curable composition according to claim 1, wherein the curable compound comprises at least one selected from the group consisting of bismaleimides and epoxy resins.

7. The curable composition of claim 1, wherein the additive comprises abietic acid.

8. The curable composition according to claim 7, wherein the content of abietic acid in the additive is 40 mass % or more based on the total amount of the additive.

9. The curable composition of claim 1, wherein the filler comprises hollow particles.

10. The curable composition according to claim 1, wherein the filler comprises a filler having insulating properties.

11. The curable composition of claim 1, wherein the filler comprises inorganic oxide particles.

12. The curable composition according to claim 11, wherein the inorganic oxide particles contain La and Mn as constituent elements.

13. An electronic component comprising: an element body containing a cured product of the curable composition according to any one of claims 1 to 12; and a pair of terminal electrodes arranged on the surface of the element body.

14. The electronic component according to claim 13, which is a high-frequency coil component and further comprises a coil portion formed of a wound conductor enclosed within the element body.

15. The electronic component according to claim 14, wherein the coil portion and the pair of terminal electrodes are of a seamless, integrated structure.

16. A circuit board comprising: a substrate containing a cured product of the curable composition according to any one of claims 1 to 12; and a conductor pattern formed on the substrate.

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