Paste composition

Abstract

To provide a paste composition that has low volume resistivity and excellent circuit adhesion and achieves a balance between print quality and conductivity.SOLUTION: A paste composition contains (A) silver particles, (B) silver powder and (C) a thermosetting compound with a molecular weight of 200 or more and 5,000 or less, and has a yield value of 40-180 Pa and a viscosity of 15-35 Pa s.SELECTED DRAWING: None

Description

Technical Field

[0001] The present disclosure relates to a paste composition. More specifically, it relates to a paste composition having a small volume resistivity that achieves both printability and conductivity.

Background Art

[0002] Some electronic components have a structure in which a plurality of insulating layers formed with conductor patterns are laminated, and the conductor patterns are sequentially connected by conductive vias formed in each insulating layer to form a coil having a spiral structure while overlapping along the lamination direction. Further, both ends of the coil are drawn out to the outer surface of the laminate and have a structure connected to external terminals.

[0003] For example, a technique is disclosed in which a coil pattern is connected by vias including first and second conductive layers made of different metals to form a coil, thereby reducing the resistance of the coil and improving the Q characteristics of the inductor (Patent Document 1). Similarly, a structure in which the conductive vias formed in each insulating layer are sequentially connected is also disclosed in a solid electrolytic capacitor (Patent Document 2).

[0004] Furthermore, in order to also be adopted in electronic components that handle large currents such as power inductors, a method of thickening the conductor pattern for the purpose of reducing wiring resistance is disclosed (Patent Document 3).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0006] With the improvement of the performance of multilayer inductors, both high conductivity of conductive vias and compatibility between circuit adhesion and printability in the simultaneous formation of conductor patterns and conductive vias are required. In addition, since there is a process of overlapping a plurality of sheets during manufacturing, post-print semi-dryness is also required. Furthermore, all of the methods disclosed in Patent Documents 1 to 3 described above used resin pastes containing silver particles with a volume resistivity of about 3×10 -4 Ω·m, and there was a limit to reducing wiring resistance.

[0007] The fired paste composition containing silver particles with a small particle size achieves low resistance by metal bonding, but there is a problem in achieving both the formability of circuit patterns by printing and the connectivity of conductive vias because the thixotropy ratio increases.

[0008] Therefore, the present disclosure provides a paste composition having a small volume resistivity, excellent circuit adhesion, and compatibility between printability and conductivity. [Means for Solving the Problems]

[0009] As a result of intensive studies to solve the above problems, the present inventors have found that the following invention can solve the problems. The present disclosure has been completed based on such findings.

[0010] That is, the present disclosure relates to the following. [1] A paste composition containing (A) silver particles, (B) silver powder, and (C) a thermosetting compound having a molecular weight of 200 or more and 5,000 or less, characterized in that the yield value is 40 to 180 Pa and the viscosity is 15 to 35 Pa·s. [2] The paste composition according to [1] above, wherein the content ratio of the (A) silver particles to the (B) silver powder is 10:90 to 50:50 by mass ratio, and the total content of the (A) silver particles and the (B) silver powder is 80 to 96% by mass based on the entire paste composition. [3] The (A) silver particles include (A1) spherical silver particles with an average particle diameter of 10 to 200 nm and (A2) plate-shaped silver particles with a central particle diameter of 0.3 to 15 μm, and the content ratio of the (A1) spherical silver particles to the (A2) plate-shaped silver particles is 0:100 to 50:50 by mass ratio. The paste composition according to [1] or [2] above is characterized by this. [4] The volume resistivity is 5×10 -6 The paste composition according to any one of [1] to [3] above is characterized by being Ω·cm or less. [5] When the mass ratio (%) of the (A) component to the total amount of the (A) component and the (B) component is Y, and the mass ratio (%) of the total amount of the (A) component and the (B) component to the entire paste composition is X, the paste composition according to any one of [1] to [4] above is characterized by satisfying the following formulas (1) and (2). 10(%) ≦ Y ≦ 30(%) (1) Y ≦ -30.376X + 2918.2(%) (2)

Advantages of the Invention

[0011] According to the present invention, it is possible to provide a paste composition having a small volume resistivity, excellent adhesion of the circuit, and compatible printability and conductivity.

Embodiments for Carrying Out the Invention

[0012] Hereinafter, the present disclosure will be described in detail with reference to one embodiment. In the present disclosure, “(meth)acrylate” means acrylate and / or methacrylate.

[0013] <Paste Composition> The paste composition of this embodiment is a paste composition containing (A) silver particles, (B) silver powder, and (C) a thermosetting compound having a molecular weight of 200 or more and 5,000 or less, and has a yield value of 40 to 180 Pa and a viscosity of 15 to 35 Pa·s.

[0014] (A) Silver Particles The (A) silver particles used in this embodiment are not particularly limited, but the thickness or the minor axis of the (A) silver particles may be 1 to 200 nm, or may be 1 to 100 nm. When the thickness or the minor axis of the (A) silver particles is 1 nm or more, the workability of the paste composition can be improved. When it is 200 nm or less, the sinterability is good, and the volume resistance after curing of the paste composition can be lowered. The thickness or the minor axis of the (A) silver particles is measured by processing observation images obtained by a transmission electron microscope (TEM) or a scanning electron microscope (SEM).

[0015] Examples of the shape of the (A) silver particles include spherical, plate-like, dendritic, rod-like, and wire-like shapes. Here, in the case where the shape of the (A) silver particles is plate-like, it is sufficient that the thickness satisfies the above range. In the case of spherical, dendritic, rod-like, or wire-like shapes, it is sufficient that the shortest diameter (minor axis) in the cross-sectional diameter satisfies the above range. Here, in the present disclosure, the thickness of the plate-like silver particles refers to the minimum distance between a pair of planes.

[0016] One kind of the (A) silver particles may be used, or two kinds may be used in combination. When two kinds of the (A) silver particles are used in combination, (A1) spherical silver particles and (A2) plate-like silver particles may be used in combination. The content ratio of (A1) spherical silver particles and (A2) plate-like silver particles may be (A1):(A2)=0:100 to 50:50 by mass ratio. By setting the content ratio of the (A2) plate-like silver particles to 50% by mass or more, the viscosity change during room temperature operation is small, and the workability is stable.

[0017] The (A1) spherical silver particles may have an average particle diameter of 10 to 200 nm. The (A1) spherical silver particles usually have a coating layer made of an organic compound on the metal surface of the silver particles or are obtained by dispersing the silver particles in an organic compound. In such a form, the contained silver particles can be prevented from directly contacting each other with their metal surfaces, so that the formation of agglomerated masses of silver particles can be suppressed, and the silver particles can be kept in a state of being individually dispersed. Note that the average particle diameter of the (A1) spherical silver particles is measured by processing the observation images obtained by a transmission electron microscope (TEM) or a scanning electron microscope (SEM). Further, the average particle diameter of the (A1) spherical silver particles may be within the range of the thickness or the minor axis of the above-mentioned (A) silver particles. The average particle diameter is calculated as the number average particle diameter of the particle diameters measured from 50 to 100 observation images of the (A1) spherical silver particles. The number average particle diameter may be calculated by calculating the average value in the same manner as the calculation of the average thickness.

[0018] As the coating layer on the surface of the (A1) spherical silver particles or the organic compound for dispersing the (A1) spherical silver particles, an organic compound having nitrogen, carbon, and oxygen as constituent elements and a molecular weight of 20,000 or less, specifically, an organic compound having a functional group such as an amino group or a carboxy group is used. Examples of the organic compound having a carboxy group used herein include one or more organic compounds selected from organic carboxylic acids having a molecular weight of 110 to 20,000, such as hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, undecanoic acid, dodecanoic acid, tetradecanoic acid, eicosanoic acid, docosanoic acid, 2-ethylhexanoic acid, oleic acid, linoleic acid, linolenic acid, and polyethylene oxide terminal dipropionate. Further, as the organic compound, carboxylic acid derivatives of the above-mentioned carboxylic acids can also be used.

[0019] In addition, examples of the organic compound having an amino group used herein include alkylamines, such as butylamine, methoxyethylamine, 2-ethoxyethylamine, hexylamine, octylamine, 3-butoxypropylamine, nonylamine, dodecylamine, hexadodecylamine, octadecylamine, cocoamine, tallowamine, hydroxytallowamine, oleylamine, laurylamine, stearylamine, and 3-aminopropyltriethoxysilane, etc. primary amines, such as dicocoamine, dihydroxytallowamine, and distearylamine, etc. secondary amines, and dodecyldimethylamine, didodecylmonomethylamine, tetradecyldimethylamine, octadecyldimethylamine, coco dimethylamine, dodecyltetradecyldimethylamine, and trioctylamine, etc. tertiary amines. In addition, other examples include diamines, such as naphthalenediamine, stearylpropylenediamine, octamethylenediamine, nonanediamine, terminal diamine polyethylene oxide, triamine terminal polypropylene oxide, and diamine terminal polypropylene oxide.

[0020] When the molecular weight of the organic compound that coats or disperses the (A1) spherical silver particles is 20,000 or less, the organic compound is likely to desorb from the surface of the silver particles, and after firing the paste, the organic compound is less likely to remain in the cured product, and as a result, the conductivity can be increased. Further, the lower limit of the molecular weight may be 50 or more. When the molecular weight is 50 or more, the storage stability of the silver particles can be improved.

[0021] The mass ratio of the (A1) spherical silver particles to the organic compound that coats or disperses the silver particles may be 90:10 to 99.5:0.5. When the mass ratio of the organic compound is 0.5% by mass or more, the aggregation of silver particles is less, and when it is 10% by mass or less, the sinterability is good, and the conductivity and thermal conductivity are good.

[0022] The (A2) plate-shaped silver particles are plate-shaped particles with uniform thickness obtained by greatly growing one metal crystal plane, different from spherical nanoparticles. Generally, they are on the micron order in size and about several nanometers in thickness, and have shapes such as triangular plate shape, hexagonal plate shape, truncated triangular plate shape, etc. Also, the upper surface in the thickness direction may be widely covered with the

[0111] plane. The (A2) plate-shaped silver particles may have a central particle diameter of 0.3 to 15 μm. In one embodiment of the present disclosure, by setting the central particle diameter of the plate-shaped silver particles within the above range, the dispersibility in the resin component can be improved. Here, the central particle diameter refers to the 50% integrated value (50% particle diameter) in the volume-based particle size distribution curve obtained by measurement with a laser diffraction particle size distribution measuring device.

[0023] Also, the thickness of the (A2) plate-shaped silver particles may be 10 to 200 nm, or may be 10 to 100 nm. The thickness is measured by processing the observation image obtained by a transmission electron microscope (TEM) or a scanning electron microscope (SEM). Furthermore, the average thickness of the (A2) plate-shaped silver particles may be within the above range. The average thickness is calculated as the number average thickness as follows.

[0024] The thicknesses measured from [n + 1] (n + 1 is, for example, about 50 to 100) observation images of the (A2) plate-shaped silver particles are arranged in order from thickest to thinnest, and the range (maximum thickness: x1, minimum thickness: x n+1 ) is divided into n equal parts, and each thickness interval is set as [x j , x j+1 (j = 1, 2, ···, n). The division in this case is an equal division on a logarithmic scale. Also, the representative thickness in each thickness interval based on the logarithmic scale is represented by the following formula.

[0025]

Equation

[0026] Furthermore, r j(j = 1, 2, ···, n) is the relative quantity (difference %) corresponding to the interval [x j , x j+1 . Assuming that the sum of the entire interval is 100%, the average value μ on the logarithmic scale can be calculated by the following formula.

[0027] [Number]

[0028] Since the above-mentioned μ is a numerical value on the logarithmic scale and has no unit as thickness, in order to convert it back to the unit of thickness, 10 μ is calculated, that is, 10 to the power of μ is calculated. This 10 μ is the number average thickness.

[0029] Also, the long side in the direction perpendicular to the thickness direction may be in the range of 8 to 150 times the thickness, or may be 10 to 50 times the thickness. Further, the short side in the direction perpendicular to the thickness direction may be in the range of 1 to 100 times the thickness, or may be 3 to 50 times the thickness.

[0030] (A2) Plate-shaped silver particles can self-sinter at 100 to 250 °C. By containing silver particles that self-sinter at 100 to 250 °C in this way, the fluidity of the silver particles is improved during thermosetting. As a result, there are more contacts between the silver particles, and the area of the contacts becomes larger, and the conductivity is significantly improved. Since the lower the self-sintering temperature, the better the sinterability, the sintering temperature of the (A2) plate-shaped silver particles may be 100 to 200 °C. Here, being able to self-sinter means sintering by heating at a temperature lower than the melting point without applying pressure or adding additives, etc.

[0031] Examples of such (A2) plate-shaped silver particles include M612 (trade name; center particle diameter 6 - 12 μm, particle thickness 60 - 100 nm, melting point 250 °C), M27 (trade name; center particle diameter 2 - 7 μm, particle thickness 60 - 100 nm, melting point 200 °C), M13 (trade name; center particle diameter 1 - 3 μm, particle thickness 40 - 60 nm, melting point 200 °C), N300 (trade name; center particle diameter 0.3 - 0.6 μm, particle thickness 50 nm or less, melting point 150 °C), etc. manufactured by Toxic Chemical Industry Co., Ltd. These plate-shaped silver particles may be used alone or in combination. In particular, in order to improve the filling rate, for example, among the above-mentioned plate-shaped silver particles, (A2) plate-shaped silver particles may be used in combination with silver particles having a relatively large particle size such as M27 and M13 and those having a small particle size such as N300.

[0032] (A2) Plate-shaped silver particles, from the viewpoint of obtaining a good connection resistance value, may have a particle thickness of 200 nm or less, a tap density (TD) of 3.0 - 7.0 g / cm 3 , and a specific surface area (BET) of 2.0 - 6.0 m 2 / g. The tap density can be measured using a tap density measuring instrument. Also, the specific surface area can be measured by the BET one-point method by nitrogen adsorption using a specific surface area measuring device.

[0033] (B) Silver powder The (B) silver powder used in this embodiment may be silver powder having a larger particle diameter than the (A) silver particles and being an inorganic filler added to impart conductivity to the resin adhesive. (B) Silver powder may have an average particle diameter greater than 0.2 μm and 20 μm or less, or may be 1 - 10 μm. The average particle diameter of the (B) silver powder refers to the 50% integration value (50% particle diameter) in the volume-based particle size distribution curve obtained by measurement with a laser diffraction particle size distribution measuring device. (B) Silver powder may be flat or flaky in order to reduce the volume resistivity. From the viewpoint of reducing the volume resistivity, the tap density of the (B) silver powder is 2.0 - 7.0 g / cm 3It may also be.

[0034] In addition, the content ratio of the component (A) and the component (B) may be 10:90 to 50:50, or 10:90 to 30:70 in terms of mass ratio. When the content ratio is within the above range, printability and conductivity can be achieved simultaneously. When the ratio of the component (A) is 10% by mass or more, the paste composition has good sinterability and the volume resistivity can be kept low. Also, when the ratio of the component (A) is 50% by mass or less, the yield value and viscosity are within the ranges described later, and good printability can be obtained.

[0035] Further, from the viewpoint of reducing the volume resistivity, the total content of the component (A) and the component (B) may be 80 to 96% by mass, 90 to 96% by mass, or 93 to 95% by mass with respect to the whole paste composition.

[0036] Furthermore, when the mass ratio (%) of the component (A) to the total amount of the component (A) and the component (B) is Y, and the mass ratio (%) of the total amount of the component (A) and the component (B) to the whole paste composition is X, it may be formulated so as to satisfy the following formulas (1) and (2). At this time, the paste composition can obtain good printability and the volume resistivity may be 5×10 -6 Ω·cm or less, or 3×10 -6 Ω·cm or less. Also, by satisfying the following formulas (1) and (2), the paste composition can achieve a volume resistivity of about 30% or 50% with respect to silver alone. 10(%)≦Y≦30(%) (1) Y≦-30.376X+2918.2(%) (2)

[0037] (C) A thermosetting compound having a molecular weight of 200 or more and 5,000 or less The (C) thermosetting compound used in this embodiment is not particularly limited as long as its molecular weight is 200 or more and 5,000 or less. From the perspective of a high silver content, it may be a liquid compound. If the molecular weight of the (C) thermosetting compound is less than 200, the pre-drying property after printing of the paste composition may decrease. If it exceeds 5,000, the dispersibility of the (A) silver particles decreases, and the yield value of the paste composition tends to increase, which may reduce the circuit embedding property. From the perspective of improving the pre-drying property and setting the yield value within the range described below, the molecular weight of the (C) thermosetting compound may be 400 or more and 3,000 or less, or may be 600 or more and 3,000 or less. Examples of the (C) thermosetting compound include epoxidized polybutadiene; difunctional or higher (meth)acrylate compounds such as dipentaerythritol hexaacrylate, trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, glycerin tri(meth)acrylate, and pentaerythritol tri(meth)acrylate.

[0038] Epoxidized polybutadiene is a compound obtained by epoxidizing polybutadiene, and it may be epoxidized polybutadiene with an epoxy equivalent of 50 to 500 (g / eq). When the epoxy equivalent is 50 g / eq or more, the viscosity does not increase too much, and the workability of the paste composition is good. When it is 500 g / eq or less, the adhesive strength during heating can be improved. The epoxy equivalent is determined by the perchloric acid method. As the epoxidized polybutadiene, those having a hydroxyl group in the molecule may be used.

[0039] The epoxidized polybutadiene may have a number average molecular weight of 500 to 10,000. When the number average molecular weight is within the above range, the adhesiveness is good, and the workability is good because the viscosity can be controlled to an appropriate value. The number average molecular weight is a value measured by gel permeation chromatography using a calibration curve of standard polystyrene.

[0040] Examples of commercially available epoxidized polybutadienes include Epolead PB4700, Epolead GT401 (both manufactured by Daicel Corporation), JP-100, and JP-200 (both manufactured by Nippon Soda Co., Ltd.). Examples of commercially available bifunctional or higher (meth)acrylate compounds include A-DPH (manufactured by Shin-Nakamura Chemical Co., Ltd.).

[0041] (C) The content of the thermosetting compound may be 0.1 to 20% by mass, 0.1 to 10% by mass, 0.1 to 7% by mass, or 0.1 to 5% by mass based on the entire paste composition. When (C) the thermosetting compound is contained in the paste composition at 0.1% by mass or more, the adhesiveness of the printed circuit is improved. When (C) the thermosetting compound is contained in the paste composition at 20% by mass or less, a low volume resistivity is achieved.

[0042] (D) Dispersant The paste composition of the present embodiment may further contain (D) a dispersant. The (D) dispersant used in the present embodiment may be ethyl cellulose, phosphate ester, or the like. Since the paste composition of the present embodiment contains the (D) dispersant, the viscosity at high rotation increases and the viscosity at low rotation tends to decrease, resulting in good shape retention after printing. (D) The content of the dispersant may be 0.01% by mass or more and less than 1% by mass, 0.01% by mass or more and less than 0.5% by mass, or 0.01% by mass or more and less than 0.25% by mass based on the entire paste composition. When (D) the dispersant is contained in the paste composition at 0.01% by mass or more, the shape after printing is improved. When (D) the dispersant is contained in the paste composition at less than 1% by mass, the volume resistivity decreases.

[0043] (E) Solvent The paste composition of this embodiment may further contain a solvent. The solvent used in this embodiment may be an alcohol or an ester having a boiling point of 200 to 220°C and a flash point of 90 to 130°C from the viewpoints of semi-drying property and continuous printability. (E) As the solvent, an alcohol-based solvent having a boiling point of 200°C or higher may be used from the viewpoints of high solubility of the resin and difficulty in causing coating unevenness due to volatilization of the solvent. Examples of the alcohol-based solvent having a boiling point of 200°C or higher include diethylene glycol, triethylene glycol, 1,3-butanediol, glycerin, benzyl alcohol, dipropylene glycol, 1,4-butanediol, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, ethylene glycol mono-2-ethylhexyl ether, dihydroterpineol, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether, terpineol, diethylene glycol butyl methyl ether, isodecanol, isotridecanol, or ethylene glycol monohexyl ether.

[0044] (E) The content of the solvent may be 1.0 to 5.0 parts by mass with respect to 100 parts by mass of the paste composition from the viewpoint of workability. When the content of the solvent (E) is 1.0 part by mass or more, the continuous printability of the paste composition becomes good, and when the content of the solvent (E) is 5.0 parts by mass or less, the semi-drying property after printing of the paste composition becomes good.

[0045] The total content of the components (A), (B), and (C) contained in the paste composition of this embodiment may be 80% by mass or more, 90% by mass or more, or 95% by mass or more.

[0046] In addition to the above components, the paste composition of this embodiment may contain, as necessary and within a range that does not inhibit the effects of this embodiment, additives generally formulated in this type of composition, such as curing accelerators, rubbers, low stress agents such as silicone, coupling agents, radical initiators, adhesion promoters, pigments, dyes, defoamers, surfactants, diluents, etc. Any one of these additives may be used, or two or more of them may be mixed and used.

[0047] (Preparation of Paste Composition) The paste composition of this embodiment can be prepared by sufficiently mixing the above-mentioned components (A) to (C), components (D) and (E) contained as necessary, and various additives, then performing kneading treatment using a disperser, kneader, three-roll mill, etc., and then defoaming.

[0048] By using the paste composition of this embodiment, it is possible to realize electronic components that handle large currents, such as power inductors with low loss and good DC superposition characteristics.

[0049] (Yield Value of Paste Composition) The paste composition of this embodiment has a yield value of 40 to 180 Pa. If the yield value is less than 40 Pa, it is likely to spread wet after printing, and the circuit shape retention may decrease. On the other hand, if the yield value exceeds 180 Pa, the via embedding property may decrease. From the perspective of achieving both the filling property of the connection via and the circuit shape retention, the yield value may be 50 to 150 Pa. Here, the yield value is the minimum stress required to flow the paste composition, and is defined as the load force or shear force at the time when the paste composition starts to flow. The yield value can be obtained, for example, by measuring the shear stress at an arbitrary shear rate using an E-type viscometer and performing a Casson plot of the shear rate and shear stress. Specifically, it can be measured by the method described in the examples.

[0050] (Viscosity of Paste Composition) The paste composition of this embodiment has a viscosity of 15 to 35 Pa·s. If the viscosity is less than 15 Pa·s, a sufficient thickness of the printed circuit cannot be obtained, and the contact resistance value may increase. On the other hand, if the viscosity exceeds 35 Pa·s, scratches are likely to occur on the printed circuit, and the embedability of vias may decrease. From the viewpoint of making the conductivity of the conductive vias good, the viscosity may be 15 to 25 Pa·s. The viscosity is the value measured at 25 °C using an E-type viscometer (3° cone). Specifically, it can be measured by the method described in the examples.

[0051] (Thixotropy of the paste composition) The thixotropy ratio (viscosity at 2 rpm / viscosity at 20 rpm) of the paste composition of this embodiment at 25 °C may be 1.5 to 3.0, or may be 1.5 to 2.5. When the thixotropy ratio is 1.5 or more, the stability of the pattern shape (bleeding of the circuit) can be obtained. On the other hand, when the thixotropy ratio is 3.0 or less, the embedability of the connection holes is excellent. The thixotropy ratio can be measured by the method described in the examples.

[0052] (Volume resistivity after printing) The volume resistivity of the paste composition of this embodiment after printing is 5×10 -6 Ω·cm or less, or may be 3×10 -6 Ω·cm or less, from the viewpoint of applying to electronic components that handle large currents such as power inductors with low loss and good DC superposition characteristics. The volume resistivity can be measured by the method described in the examples.

[0053] (Manufacturing method of chip-type electronic components) An example of the manufacturing process of a laminated inductor using the paste composition of this embodiment is shown below. (1) A step of printing a metal magnetic material paste mainly composed of a binder resin and metal magnetic alloy powder on a release film to form a sheet. Examples of the metal magnetic alloy powder include powders of Fe-based soft magnetic materials such as α-Fe, Fe-Si, Fe-Si-Cr, Fe-Si-Al, Fe-Ni, and Fe-Co. (2) A step of forming connection holes by perforating connection parts with a laser or the like for interlayer connection in the sheet-like metal magnetic material sheet. (3) A step of printing a conductor pattern for a coil (for example, thickness 20 μm × width 200 μm) on the metal magnetic material sheet. (4) A step of filling the formed connection holes with a paste composition containing (A) silver particles, (B) silver powder, and (C) a thermosetting compound simultaneously with the printing of the conductor pattern for the coil. (5) A step of pre-drying the filled paste composition (for example, at 80°C for 20 minutes). (6) Peeling the release film from the pre-dried metal magnetic material sheet, laminating a plurality of metal magnetic material sheets, and pressing them (for example, 1 N / m 2 ) to form a laminate. (7) A step of dicing the laminate into individual pieces. (8) A step of heat-baking the diced laminate (for example, at 300 to 600°C for 5 minutes to several hours).

[0054] An example of the manufacturing process of the laminated capacitor using the paste composition of this embodiment is shown below. (1) A step of forming a dielectric layer on the surface of the valve-acting metal substrate. (2) A step of forming an insulating layer by applying an insulating resin on the dielectric layer. (3) A step of forming a solid electrolyte layer on the dielectric layer. (4) A step of forming a conductor layer using a paste composition containing (A) silver particles, (B) silver powder, and (C) a thermosetting compound on the solid electrolyte layer. (5) A step of forming a sealing layer on the insulating layer and on the conductor layer of the capacitor element so as to cover one main surface of the capacitor element with the insulating layer formed. (6) A step of forming a through hole penetrating the sealing layer on the conductor layer of the capacitor element by laser treatment or the like. (7) A step of forming an external electrode and connecting it to the through electrode exposed on the surface of the sealing layer.

Examples

[0055] Next, the present embodiment will be specifically described by way of examples. However, the present embodiment is not limited in any way by these examples.

[0056] (Examples 1 to 7, Comparative Examples 1 to 6) Each component was mixed according to the formulations shown in Tables 1 and 2, and kneaded with a roll to obtain a paste composition. The obtained paste composition was evaluated by the method described below. The results are shown together in Tables 1 and 2. The materials used in the examples and comparative examples had the following characteristics.

[0057] [(A) Silver particles] ·(A1) Spherical silver particles: Mdot-CF108 (trade name, manufactured by Mitsuboshi Belting Ltd.; average particle diameter: 100 nm) The average particle diameter of the (A1) spherical silver particles was calculated as the number average particle diameter of the particle diameters measured from 50 observation images of the (A1) spherical silver particles obtained by a transmission electron microscope (TEM). ·(A2) Plate-shaped silver particles: N300 (trade name, manufactured by Tokusen Kogyo Co., Ltd.; central particle diameter: 0.3 μm, thickness: 30 nm or less) The central particle diameter of the (A2) plate-shaped silver particles was determined from the particle diameter (50% particle diameter, D50) at which the integrated volume was 50% in the particle size distribution measured using a laser diffraction particle size distribution measuring device (manufactured by Shimadzu Corporation, trade name: SALAD-7500nano). The thickness of the (A2) plate-shaped silver particles was calculated as the average value of the particle thicknesses measured from 50 observation images of the (A2) plate-shaped silver particles obtained by a transmission electron microscope (TEM).

[0058] [(B) Silver powder] ·(B1) Flaky silver powder: TC-506C (trade name, manufactured by Tokuryu Honten Co., Ltd.; average particle diameter: 4.0 μm) The average particle diameter of the above-mentioned (B) silver powder was determined from the particle diameter (50% particle diameter, D50) at which the cumulative volume was 50% in the particle size distribution measured using a laser diffraction particle size distribution measuring device (manufactured by Shimadzu Corporation, product name: SALAD-7500nano).

[0059] [(C) Thermosetting compound with a molecular weight of 200 or more and 5,000 or less] · (C1) Thermosetting compound: Epoxidized polybutadiene (manufactured by Nippon Soda Co., Ltd., product name: JP-200, molecular weight 2,200, epoxy equivalent 230 g / eq) · (C2) Thermosetting compound: Dipentaerythritol hexaacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., product name: A-DPH, molecular weight 578) [Thermosetting compound other than component (C)] · (X1) Thermosetting compound: 1,4-Cyclohexanedimethanol monoacrylate (manufactured by Mitsubishi Chemical Corporation, product name: CHDMMA, molecular weight 198)

[0060] [(D) Dispersant] · Ethyl cellulose (manufactured by Dow Chemical Japan, product name: Ethocel STD-4IND)

[0061] [(E) Solvent] · Butyl carbitol (manufactured by Tokyo Chemical Industry Co., Ltd.)

[0062] [Other components] · Radical initiator: PERKEMIL (registered trademark) D (product name, manufactured by NOF Corporation) · Coupling agent: LS-3380 (manufactured by Shin-Etsu Chemical Co., Ltd.)

[0063] [Evaluation method] (1) Viscosity Using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd., product name: VISCOMETER-TV22, applicable cone plate type rotor: 3°×R17.65), the value at a temperature of 25°C and a rotation speed of 2 rpm was measured.

[0064] (2) Yield value Using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd., product name: VISCOMETER-TV22, applicable cone plate type rotor: 3°×R17.65), the shear stress at a shear rate of 1 (1 / s), 2 (1 / s), 4 (1 / s), 10 (1 / s), 20 (1 / s), 40 (1 / s), 100 (1 / s), and 200 (1 / s) was measured at a temperature of 25°C. The shear rate and shear stress were plotted on a Casson plot, and the yield value was calculated.

[0065] (3) Thixotropy ratio Using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd., product name: VISCOMETER-TV22, applicable cone plate type rotor: 3°×R17.65), the viscosity at 25°C was measured at rotational speeds of 2 rpm and 20 rpm, and the ratio of the viscosity at 2 rpm to the viscosity at 20 rpm (viscosity at 2 rpm / viscosity at 20 rpm) was defined as the thixotropy ratio.

[0066] (4) Tack-free property A circuit with a thickness of 20 μm × width of 200 μm was screen-printed using the paste composition, then heated at 80°C for 20 minutes, allowed to stand at 25°C for 1 hour, and then a finger-touch test was performed on the printed surface. The case where there was no tack was judged as "〇", the case where there was tack was judged as "△", and the case where it stuck to the finger was judged as "×".

[0067] (5) Volume resistivity The paste composition was applied to a glass substrate (thickness 1 mm) by screen printing to a size of 5 mm × 50 mm and a thickness of 30 μm, and cured at 200°C for 60 minutes. The electrical resistance of the obtained wiring was measured using a resistivity meter (manufactured by Mitsubishi Chemical Analytech Co., Ltd., product name "MCP-T600") by the four-terminal method.

[0068] (6) Circuit adhesion A circuit with a thickness of 20 μm × width of 200 μm was screen-printed using the paste composition. Using the obtained circuit, a cross-cut test by tape peeling (JIS-K5600-5-6:1999) was performed. The case where no peeling occurred was judged as "〇", and the case where peeling occurred was judged as "×".

[0069] (7) Printability A circuit with a thickness of 20 μm and a width of 200 μm was screen-printed using the paste composition. The surface appearance after printing was visually observed, and when there was no abnormality in the printed circuit, it was judged as "〇", when mesh marks were confirmed on the surface of the printed circuit, it was judged as "△", and when the printed circuit was jagged, it was judged as "×".

[0070] (8) Embeddability A circuit with a thickness of 20 μm and a width of 200 μm was screen-printed using the paste composition. The inside of the hole after printing was observed, and when the inside of the hole was filled with the paste composition, it was judged as "〇", and when the inside of the hole was not filled with the paste composition, it was judged as "×".

[0071]

Table 1

[0072]

Table 2

[0073] (C) In Examples 1 to 7 using a paste composition containing a thermosetting compound having a molecular weight of 200 or more and 5,000 or less, with a yield value of 40 to 180 Pa and a viscosity of 15 to 35 Pa·s, all had a volume resistivity as low as 3.5×10 -6 Ω·cm or less, excellent conductivity, excellent printability, good post-printing pre-drying property, and it was confirmed that they were excellent in circuit adhesion and embeddability.

Claims

1. A paste composition comprising (A) silver particles, (B) silver powder (provided that the (A) silver particles are not included), (C) a thermosetting compound having a molecular weight of 200 or more and 5,000 or less, and (D) a dispersant, having a yield value of 40 to 180 Pa and a viscosity of 15 to 35 Pa·s, wherein the (A) silver particles have a thickness or a minor axis of 1 to 100 nm, the (B) silver powder has an average particle diameter greater than 0.2 μm and 20 μm or less, the content ratio of the (A) silver particles to the (B) silver powder is 10:90 to 50:50 by mass ratio, the total content of the (A) silver particles and (B) silver powder is 80 to 96% by mass based on the entire paste composition, the (C) thermosetting compound is 0.1 to 10% by mass based on the entire composition, the (C) thermosetting compound is at least one of epoxidized polybutadiene and dipentaerythritol hexaacrylate, the (D) dispersant is 0.01% by mass or more and less than 1% by mass based on the entire composition, and the (D) dispersant is ethyl cellulose, characterized in that it is a paste composition, wherein the (A) silver particles include (A1) spherical silver particles having an average particle diameter of 10 to 100 nm and (A2) plate-shaped silver particles having a central particle diameter of 0.3 to 15 μm, and the content ratio of the (A1) spherical silver particles to the (A2) plate-shaped silver particles is 0:100 to 50:50 by mass ratio, characterized in that it is a paste composition.

2. The paste composition according to claim 1, characterized in that the volume resistivity is 5×10 -６ Ω·cm or less.

3. The paste composition according to Claim 1 or 2, characterized in that when the mass ratio (%) of the (A) component to the total amount of the (A) component and the (B) component is Y, and the mass ratio (%) of the total amount of the (A) component and the (B) component to the entire paste composition is X, the following formulas (1) and (2) are satisfied. 10 (%) ≤ Y ≤ 30 (%) (1) Y ≤ -30.376X + 2918.2 (%) (2)

Images