Photosensitive conductive paste, method for producing laminated electronic component, and laminated electronic component

Abstract

To provide a photosensitive conductive paste, a method for producing a laminated electronic component, and a laminated electronic component, achieving controlled shrinkage behavior during a firing process.SOLUTION: A photosensitive conductive paste includes: a conductive powder; an organic component; and a solvent. The organic component includes an alkali-soluble polymer, a photosensitive monomer, and a photopolymerization initiator. A cured product of the organic component exhibits a thermal decomposition ability in an oxygen atmosphere that satisfies conditions A and B defined below. (Condition A) Thermogravimetry shows a weight loss rate of less than 50% at 300°C. (Condition B) Thermogravimetry shows a weight loss rate of 100% at 700°C.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a photosensitive conductive paste, a method for manufacturing a laminated electronic component, and a laminated electronic component.

Background Art

[0002] In recent years, laminated electronic components such as laminated ceramic circuit boards have been manufactured by forming internal electrodes using a photosensitive conductive paste. The internal electrodes are formed by sintering the conductive powder contained in the photosensitive conductive paste after patterning the photosensitive conductive paste and then firing. Examples of the photosensitive conductive paste used for laminated electronic components include those disclosed in JP-A-2002-169274 (Patent Document 1) and JP-A-2007-18884 (Patent Document 2).

[0003] JP-A-2002-169274 discloses a photosensitive conductive paste containing, as main components, 40 to 80 wt% of conductive powder, 3 to 20 wt% of a photopolymerizable compound, 10 wt% or less of a photoinitiator, and 0.3 to 2.5 wt% of one or more non-conductive metal oxides. The non-conductive metal oxides are generally called "co-materials". In JP-A-2002-169274, it is stated that the firing shrinkage of the internal electrodes can be reduced because of the inclusion of co-materials.

[0004] JP-A-2007-18884 discloses a photosensitive conductive paste containing a first conductive powder having an average particle size of 5 μm or less obtained by an atomization method and a second conductive powder having an average particle size in the range of 0.2 to 2.0 μm obtained by a wet reduction method in a weight ratio within the range of 20 / 80 ≤ (first conductive powder / second conductive powder) ≤ 80 / 20. In JP-A-2007-18884, it is stated that the firing shrinkage of the internal electrodes can be reduced because of the inclusion of the first conductive powder having a relatively large average particle size.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-169274 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-18884 [Summary of the Invention] [Problems to be Solved by the Invention]

[0006] However, it has been found that delamination may occur even if the firing shrinkage of the internal electrode is reduced, when the shrinkage of the photosensitive conductive paste during firing does not correspond to the shrinkage of the base material.

[0007] Therefore, an object of the present disclosure is to provide a photosensitive conductive paste in which the shrinkage behavior during firing is controlled. Further, an object of the present disclosure is to provide a method for manufacturing a laminated electronic component and a laminated electronic component using this photosensitive conductive paste. [Means for Solving the Problems]

[0008] In order to solve the above problems, a photosensitive conductive paste which is one aspect of the present disclosure contains conductive powder, an organic component, and a solvent, the organic component contains an alkali-soluble polymer, a photosensitive monomer, and a photopolymerization initiator, and the cured product of the organic component satisfies the following conditions A and B in terms of thermal decomposability in an oxygen atmosphere. (Condition A) In thermogravimetric measurement, the weight loss rate at 300 ° C is less than 50%. (Condition B) In thermogravimetric measurement, the weight loss rate at 700 ° C is 100%.

[0009] According to the above aspect, since the shrinkage behavior of the photosensitive conductive paste during firing is controlled, when this is used as the internal electrode of a multilayer electronic component, the deviation from the shrinkage behavior of the green body material during firing is reduced, and delamination is suppressed. In addition, since a co-material is not an essential component and an increase in the large particle size of the conductive powder is not required, the resolution during photolithographic patterning is improved, and the electrical resistance of the formed internal electrode can be reduced.

Effects of the Invention

[0010] According to the photosensitive conductive paste according to the present disclosure, the shrinkage behavior of the photosensitive conductive paste during firing is controlled.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0012] Hereinafter, a photosensitive conductive paste, a method for manufacturing a multilayer electronic component, and a multilayer electronic component, which are one aspect of the present disclosure, will be described in detail with reference to the illustrated embodiments. Note that the drawings include some schematic ones and may not reflect actual dimensions and ratios.

[0013] (Overall Configuration of Multilayer Electronic Component) FIG. 1 is a perspective view schematically showing a multilayer electronic component. FIG. 2 is an exploded perspective view schematically showing a multilayer electronic component. In FIG. 1, the green body is drawn transparently so that the structure can be easily understood, but it may be translucent or opaque. In FIG. 1, the description of the coil is omitted so that the structure can be easily understood. In FIG. 2, the description of the external electrode is omitted for ease of viewing.

[0014] Hereinafter, the multilayer electronic component will be described by taking the multilayer coil component as an example. However, the multilayer electronic component of the present disclosure is not limited to the multilayer coil component, and can be applied to various multilayer electronic components such as multilayer capacitor components and multilayer LC composite components.

[0015] As shown in FIGS. 1 and 2, the multilayer electronic component 10 includes a body 4, a coil 5 provided in the body 4, and a first external electrode 6a and a second external electrode 6b provided on the body 4. The coil 5 corresponds to the "internal electrode" described in the claims.

[0016] The shape of the body 4 is not particularly limited, but in this embodiment, it is substantially rectangular parallelepiped. The outer surface of the body 4 has a first end face 41, a second end face 42 facing the first end face 41, a first side face 43 connecting the first end face 41 and the second end face 42, a second side face 44 facing the first side face 43, a bottom face 45 connecting the first end face 41, the second end face 42, the first side face 43, and the second side face 44, and a top face 46 facing the bottom face 45 and connecting to the first end face 41, the second end face 42, the first side face 43, and the second side face 44. The direction from the first end face 41 to the second end face 42 is defined as the X direction, the direction from the first side face 43 to the second side face 44 is defined as the Y direction, and the direction from the bottom face 45 to the top face 46 is defined as the Z direction. In this specification, the Z direction may be referred to as the upper side in some cases.

[0017] The base body 4 is formed by laminating a plurality of insulating layers 40. The insulating material of the insulating layer 40 is not particularly limited. For example, it includes borosilicate glass and an inorganic filler. The inorganic filler is, for example, glass powder and ceramic aggregates such as alumina. The lamination direction of the insulating layer 40 is parallel to the Z direction. That is, the insulating layer 40 is in a layered form spreading in the XY plane. In the insulating layer 40 located between adjacent coil wirings 2 among the plurality of coil wirings 2 described later, via holes 3 are provided at positions where the adjacent coil wirings 2 are connected. The via holes 3 penetrate the insulating layer 40 in the thickness direction (Z direction). In the present application, "parallel" is not limited to a strict parallel relationship, and includes a substantial parallel relationship in consideration of the range of actual variations. Note that in the base body 4, the interfaces between the plurality of insulating layers 40 may not be clear due to firing or the like.

[0018] The first external electrode 6a and the second external electrode 6b are made of a conductive material such as Ag, Cu, Au, or an alloy having these as main components, for example. In this embodiment, the first external electrode 6a is continuously provided on the entire surface of the first end face 41 of the base body 4, the end portion on the first end face 41 side of the first side face 43, the end portion on the first end face 41 side of the second side face 44, the end portion on the first end face 41 side of the bottom face 45, and the end portion on the first end face 41 side of the top face 46. Also, the second external electrode 6b is continuously provided on the entire surface of the second end face 42 of the base body 4, the end portion on the second end face 42 side of the first side face 43, the end portion on the second end face 42 side of the second side face 44, the end portion on the second end face 42 side of the bottom face 45, and the end portion on the second end face 42 side of the top face 46. In short, each of the first external electrode 6a and the second external electrode 6b is a five-sided electrode. However, it is not limited to this. For example, the first external electrode 6a may be an L-shaped electrode continuously provided on a part of the first end face 41 and a part of the bottom face 45. Similarly, the second external electrode 6b may be an L-shaped electrode continuously provided on a part of the second end face 42 and a part of the bottom face 45, for example.

[0019] The coil 5 is a sintered body of a photosensitive conductive paste containing conductive powder such as Ag or Cu. The coil 5 is wound spirally along the stacking direction of the insulating layer 40. The first end 5a of the coil 5 is exposed from the first end face 41 of the base body 4 and is connected to the first external electrode 6a. The second end 5b of the coil 5 is exposed from the second end face 42 of the base body 4 and is connected to the second external electrode 6b.

[0020] When viewed from the axial direction, the coil 5 is formed in a rectangular shape, but is not limited to this shape. The shape of the coil 5 may be, for example, circular, elliptical, rectangular, or other polygons. Also, the axial direction of the coil 5 is parallel to the Z direction, and it is wound along the axial direction. The axis of the coil 5 means the central axis of the spiral shape of the coil 5.

[0021] The coil 5 has a plurality of coil wirings 2 stacked along the axial direction and a via wiring (not shown) that extends along the axial direction and connects the coil wirings 2 adjacent to each other in the axial direction. The plurality of coil wirings 2 are each wound along a plane, arranged side by side in the axial direction, and form a spiral while being electrically connected in series.

[0022] The coil wiring 2 is formed by being wound on the main surface (XY plane) of the insulating layer 40 orthogonal to the axial direction. The number of turns of the coil wiring 2 is less than one turn, but may be one turn or more. The via wiring is provided in the via hole 3 of the insulating layer 40 and penetrates the insulating layer 40 in the thickness direction (Z direction). And the coil wirings 2 adjacent to each other in the stacking direction are electrically connected in series via the via wiring.

[0023] In such a multilayer electronic component 10, a plurality of insulating layers 40 and a plurality of patterning layers of the photosensitive conductive paste are alternately stacked, and each of the plurality of insulating layers 40 and the plurality of patterning layers of the photosensitive conductive paste is sintered. Thereby, the base body 4 is formed from the plurality of insulating layers 40, and the coil 5 is formed from the plurality of patterning layers of the photosensitive conductive paste.

[0024] (Detailed Configuration of Photosensitive Conductive Paste) Next, the detailed configuration of the photosensitive conductive paste used for forming the coil 5 will be described. Hereinafter, the photosensitive conductive paste used for forming the coil 5 of the multilayer electronic component 10, which is a multilayer coil component, will be described. However, the photosensitive conductive paste of the present disclosure is not limited thereto, and can be used for forming internal electrodes of various multilayer electronic components such as multilayer capacitor components and multilayer LC composite components. For example, in the case of a multilayer capacitor component, the photosensitive conductive paste of the present disclosure can be used for forming capacitor electrodes.

[0025] The photosensitive conductive paste contains conductive powder, an organic component, and a solvent.

[0026] <Conductive powder> The conductive powder is sintered by firing to become the conductor of the coil 5. The type of the conductive powder is not particularly limited, but it may be silver (Ag) or copper (Cu) in order to reduce the electrical resistance of the formed coil 5. The content of the conductive powder with respect to the photosensitive conductive paste may be 65% by weight or more and 90% by weight or less. From the viewpoint of suppressing the shrinkage of the photosensitive conductive paste after firing, the content of the conductive powder with respect to the photosensitive conductive paste may be 70% by weight or more and 85% by weight or less.

[0027] The average particle diameter D50 (median diameter) of the conductive powder may be 0.5 μm or more and 5.0 μm or less from the viewpoint of forming a fine pattern of the coil 5. The average particle diameter D50 is the 50% particle diameter in the volume-based particle size distribution measured by a laser diffraction type particle size distribution measuring device (for example, MT3000 manufactured by Microtrac Bell).

[0028] The conductive powder may be silver (Ag) powder. The average particle diameter D50 of the Ag powder may also be 0.5 μm or more and 5.0 μm or less. In particular, the conductive powder may be atomized Ag powder manufactured by an atomization method. The atomized Ag powder has a larger crystallite diameter of the conductive powder and less organic impurities than the Ag powder manufactured by a wet reduction method. Therefore, the electrical resistance of the formed coil 5 is further reduced.

[0029] <Organic component> The organic component includes at least an alkali-soluble polymer, a photosensitive monomer, and a photoinitiator. The content of the organic component may be 5% by weight or more, and may be 8% by weight or more, based on the photosensitive conductive paste. The content of the organic component may be 20% by weight or less, and may be 15% by weight or less, based on the photosensitive conductive paste.

[0030] The organic component decomposes by heating. The weight loss (in this case, synonymous with volume reduction) of this organic component causes the shrinkage of the coil 5. However, if the shrinkage behavior of the photosensitive conductive paste during firing corresponds to the shrinkage behavior of the base material, delamination, which is a structural defect that may occur between the resulting coil 5 and the base body 4, can be suppressed.

[0031] The base material typically contains borosilicate glass, and its softening point is usually above 700°C. When the glass component softens by heating above 700°C, the sintering of the base material proceeds rapidly and it is densified. That is, the base material exhibits a shrinkage behavior in which the shrinkage is small until the glass component softens, and then shrinks rapidly after the glass component softens.

[0032] The thermal decomposability of the cured product of the organic component (hereinafter, may be simply referred to as "cured product") used in the photosensitive conductive paste according to the present disclosure satisfies the following conditions A and B. (Condition A) In thermogravimetric measurement, the weight loss rate at 300°C is less than 50%. (Condition B) In thermogravimetric measurement, the weight loss rate at 700°C is 100%.

[0033] Condition A indicates that the degree of thermal decomposition of the cured product is small up to 300°C. That is, it means that the shrinkage rate of the photosensitive conductive paste is small up to 300°C. At temperatures up to 300°C, as described above, the shrinkage of the base material is also small. That is, up to 300°C, the shrinkage of both the photosensitive conductive paste and the base material is small, and the shrinkage behaviors of both correspond. The weight loss rate of the cured product at 300°C (hereinafter, may be referred to as ΔTG) may be less than 40%, may be less than 35%, or may be less than 30%.

[0034] However, it is required that the thermal decomposition of the organic components contained in the photosensitive conductive paste is completed before the glass component of the base material starts to soften. When the glass component of the base material starts to soften, if the above organic components remain, the decomposed and gasified organic components will be trapped by the molten glass component. The gaseous organic components remaining inside the multilayer electronic component 10 remain in the base material as voids, which is one of the causes of structural defects.

[0035] Condition B indicates that the decomposition of the cured product is completed by 700°C. That is, it means that the decomposition of the organic components contained in the photosensitive conductive paste is completed by 700°C. When exceeding 700°C, as described above, the glass component contained in the base material starts to soften. By the decomposition of the cured product being completed by 700°C, the trapping of the gasified organic components as described above is suppressed. The cured product may have a weight loss rate of 100% at 600°C.

[0036] By satisfying both of the above Conditions A and B, it can be said that the organic components contained in the photosensitive conductive paste decompose gently up to 300°C and complete the decomposition (the weight loss rate reaches 100%) between exceeding 300°C and reaching 700°C. That is, since the shrinkage behavior of the base material during firing and the shrinkage behavior of the photosensitive conductive paste correspond, suppression of delamination can be expected.

[0037] The above-mentioned cured product is obtained by mixing each organic component at a ratio to be blended in the photosensitive conductive paste and then curing. The above-mentioned cured product may be obtained by curing a mixture obtained by mixing a photosensitive monomer, an alkali-soluble polymer, and a photopolymerization initiator at a ratio to be blended in the photosensitive conductive paste. This is because the blending amounts of other organic components (typically, additives described later) are small and the influence on ΔTG is small.

[0038] In the above-mentioned mixture, the content of the photosensitive monomer is, for example, 30% by weight or more and 60% by weight or less. In the above-mentioned mixture, the content of the alkali-soluble polymer is, for example, 30% by weight or more and 60% by weight or less. In the above-mentioned mixture, the content of the photopolymerization initiator is, for example, 3% by weight or more and 10% by weight or less.

[0039] The thermal decomposability of the above-mentioned cured product in an oxygen atmosphere may further satisfy the following condition C. (Condition C) In thermogravimetric measurement, in the range of 300 °C or more and 400 °C or less, the change in the weight loss rate is 70% or less.

[0040] Condition C indicates that the weight of the above-mentioned cured product decreases with a certain gentleness even after exceeding 300 °C. This means that the shrinkage of the photosensitive conductive paste proceeds gently until the degreasing is completed. This shrinkage behavior corresponds more closely to the shrinkage behavior of the green body material during firing, so suppression of delamination can be further expected.

[0041] The change in the weight loss rate in the range of 300 °C or more and 400 °C or less refers to the weight loss rate ΔTG of the cured product at 300 °C 300 and the weight loss rate ΔTG of the cured product at 400 °C 400 and the difference (|ΔTG 300 -ΔTG 300 |).

[0042] ≪Alkali-soluble polymer≫ The alkali-soluble polymer is neutralized with a basic compound to be solubilized. The alkali-soluble polymer is removed together with the uncured photosensitive monomer and conductive powder, for example, during development using an alkaline developer. On the other hand, when the photosensitive monomer is polymerized by active energy rays, the alkali-soluble polymer present in the vicinity thereof forms a film together with the polymer of the photosensitive monomer, and forms, for example, part of the internal electrode pattern. Thereby, the adhesion of the internal electrode pattern to the insulating layer can be improved.

[0043] The content of the alkali-soluble polymer may be 30% by weight or more, and may be 35% by weight or more, based on the organic components. The content of the alkali-soluble polymer may be 60% by weight or less, and may be 55% by weight or less, based on the organic components.

[0044] The photosensitive conductive paste may contain one type of alkali-soluble polymer, or may contain two or more types of alkali-soluble polymers.

[0045] The alkali-soluble polymer has at least one acid group in the side chain. As the acid group, typically, a carboxy group is mentioned. The alkali-soluble polymer contains, as the main chain, for example, a polymer chain having at least one of a carbon-carbon bond, an ether bond, a urea bond, an ester bond, and a urethane bond. From the viewpoint of transparency, the main chain of the alkali-soluble polymer may contain a polymer chain having a carbon-carbon bond.

[0046] The alkali-soluble polymer having at least one carboxy group in the side chain and containing a polymer chain having a carbon-carbon bond as the main chain is obtained, for example, by copolymerization of an unsaturated carboxylic acid and an ethylenically unsaturated compound. As the alkali-soluble polymer, typically, a carboxy group-containing acrylic polymer is mentioned.

[0047] Examples of the unsaturated carboxylic acid include acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, vinylacetic acid, and dimers and anhydrides thereof. These may be used singly or in combination of two or more.

[0048] Examples of the ethylenically unsaturated compound include acrylic esters such as methyl acrylate, ethyl acrylate, butyl acrylate, isobutyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, and isobornyl acrylate; methacrylic esters such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, and isobornyl methacrylate; fumaric esters such as monoethyl fumarate; and styrene. These may be used singly or in combination of two or more.

[0049] The carboxy group of the alkali-soluble polymer may be introduced after the main chain is formed. The carboxy group of the alkali-soluble polymer may be introduced, for example, by reacting an unsaturated monocarboxylic acid with a compound having the above polymer chain having an epoxy group in the side chain and then further reacting with a saturated or unsaturated polycarboxylic acid anhydride.

[0050] The alkali-soluble polymer may have an unsaturated bond. The unsaturated bond of the alkali-soluble polymer may be introduced, for example, by adding a monomer having a polymerizable functional group (typically an epoxy group) that can react with a carboxy group in the side chain.

[0051] The alkali-soluble polymer may particularly include a copolymer containing an easily detachable polymer unit showing main-chain cleavage type decomposability during thermal decomposition. This facilitates the control of the thermal decomposability (shrinkability) of the cured product, and makes it easier to obtain a photosensitive conductive paste satisfying the above conditions A and B (and further condition C. The same applies hereinafter).

[0052] The weight ratio of the copolymer containing the above-mentioned easily detachable polymerization unit to the total amount of the alkali-soluble polymer may be 50% by mass or more, may be 80% by weight or more, and may be 100% by weight.

[0053] Typical examples of the easily detachable polymerization unit include units derived from ethylene monomers (the following chemical formula (1)), units derived from propylene monomers (the following chemical formula (2)), units derived from isobutylene monomers (the following chemical formula (3)), units derived from styrene monomers (the following chemical formula (4)), units derived from methyl methacrylate monomers (the following chemical formula (5)), units derived from tetrafluoroethylene monomers (the following chemical formula (6)), and units derived from α-methylstyrene monomers (the following chemical formula (7)). These may be contained in the above copolymer alone or in combination of two or more.

[0054]

Chemical formula

[0055]

Chemical formula

[0056]

Chemical formula

[0057]

Chemical formula

[0058]

Chemical formula

[0059]

Chemical formula

[0060] [Chemical formula]

[0061] The ratio (N1 / N) of the number N1 of easily detachable polymerization units to the total number N of all polymerization units constituting the copolymer may be 0.2 or more and 0.6 or less. Thereby, a photosensitive conductive paste satisfying the above conditions A and B can be more easily obtained. Hereinafter, an alkali-soluble polymer in which the ratio (N1 / N) is 0.2 or more and 0.6 or less may be referred to as a "specific alkali-soluble polymer". The ratio (N1 / N) may be 0.4 or less.

[0062] The ratio (N1 / N) can be calculated by dividing the charged molar number of the monomer forming the easily detachable polymerization unit (hereinafter referred to as the easily detachable monomer) by the total charged molar number of the plurality of raw material monomers used in the production of the specific alkali-soluble polymer.

[0063] The easily detachable monomer is a monomer that forms an easily detachable polymerization unit (for example, the unit represented by the above chemical formulas (1) to (7)) when polymerized. Examples of the easily detachable monomer include ethylene, propylene, isobutylene, styrene, methyl methacrylate, tetrafluoroethylene, and α-methylstyrene.

[0064] The weight average molecular weight (Mw) of the alkali-soluble polymer may be 5,000 or more and 50,000 or less. The acid value of the alkali-soluble polymer may be 30 mgKOH / g or more and 150 mgKOH / g or less.

[0065] <<Photosensitive monomer>> The photosensitive monomer reacts with a photoinitiator to generate monomer radicals. The monomer radicals polymerize to form a polymer.

[0066] The photosensitive conductive paste may contain one type of photosensitive monomer or may contain two or more types of photosensitive monomers.

[0067] The photosensitive monomer is not limited as long as it has at least one radical-reactive group. Examples of the radical-reactive group include at least one selected from the group consisting of an acrylamide group, an acryloyl group, a methacryloyl group, an allyl group, a vinyl group, a styryl group, and a mercapto group. The photosensitive monomer may have at least one (meth)acryloyl group as the radical-reactive group. The “(meth)acryloyl group” represents an acryloyl group and / or a methacryloyl group.

[0068] (Meth)acrylic monomers having a (meth)acryloyl group include monofunctional (meth)acrylate monomers such as stearyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, lauryl (meth)acrylate, 2-phenoxyethyl (meth)acrylate, isodecyl (meth)acrylate, isooctyl (meth)acrylate, tridecyl (meth)acrylate, caprolactone (meth)acrylate, ethoxylated nonylphenol (meth)acrylate; difunctional (meth)acrylate monomers such as tripropylene glycol di(meth)acrylate, EO-modified diacrylate of isocyanuric acid, 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, diethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, ethoxylated bisphenol A di(meth)acrylate, propoxylated neopentyl glycol di(meth)acrylate; trifunctional (meth)acrylate monomers such as glycerin tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, propoxylated glyceryl tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, ethoxylated pentaerythritol tri(meth)acrylate, tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate, caprolactone-modified tris(2-hydroxyethyl)isocyanurate tri(meth)acrylate, hexanediol tri(meth)acrylate, tripropylene glycol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, EO-modified trimethylolpropane tri(meth)acrylate; tetrafunctional (meth)acrylate monomers such as pentaerythritol tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, tripentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, ethoxylated pentaerythritol tetra(meth)acrylate;Pentafunctional (meth)acrylate monomers such as dipentaerythritol penta(meth)acrylate, tripentaerythritol penta(meth)acrylate, and dipentaerythritol monohydroxypenta(meth)acrylate; hexafunctional (meth)acrylate monomers such as dipentaerythritol hexa(meth)acrylate, caprolactone-modified dipentaerythritol hexa(meth)acrylate, and tripentaerythritol hexa(meth)acrylate; and (meth)acrylate monomers having seven or more functional groups such as tripentaerythritol hepta(meth)acrylate and tripentaerythritol octa(meth)acrylate. These may be used alone or in combination of two or more.;

[0069] The photosensitive monomer may be a (meth)acrylate monomer having three or more functional groups, may be a (meth)acrylate monomer having four or more functional groups, or may be a (meth)acrylate monomer having five or more functional groups. The photosensitive monomer may be dipentaerythritol monohydroxypenta(meth)acrylate.

[0070] The ratio (Wm / Wp) of the blending weight Wm of the photosensitive monomer to the blending weight Wp of the alkali-soluble polymer may be 0.2 or more and 0.9 or less. Thereby, a photosensitive conductive paste satisfying the above conditions A and B is particularly easily obtained.

[0071] In particular, when the ratio (N1 / N) regarding the alkali-soluble polymer is less than 0.3, the upper limit of the ratio (Wm / Wp) may be 0.5, 0.4, or 0.3.

[0072] In particular, when the ratio (N1 / N) regarding the alkali-soluble polymer is 0.3 or more and 0.6 or less, the lower limit of the ratio (Wm / Wp) may be 0.2, 0.3, or 0.4.

[0073] ≪Photoinitiator≫ The photoinitiator generates highly reactive radicals upon exposure to active energy rays. The radicals add to the photosensitive monomer, triggering the initiation reaction of the photosensitive monomer. The radicals are generated in a chain reaction, and eventually, a polymer derived from the photosensitive monomer is formed. The content of the photoinitiator may be 3 wt% or more, and may be 5 wt% or more, based on the organic components. The content of the photoinitiator may be 10 wt% or less, and may be 8 wt% or less, based on the organic components.

[0074] Examples of the photoinitiator include at least one selected from the group consisting of benzoin or benzoin ether compounds, alkylphenone compounds, benzophenone compounds, oxime ester compounds, acylphosphine oxide compounds, and α-ketoester compounds.

[0075] The organic components may further contain additives such as a sensitizer, an antifoaming agent, an anti-settling agent, and a dispersant.

[0076] <Solvent> The solvent is not particularly limited, and examples include ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, ethylene glycol monoethylhexyl ether, propylene glycol monobutyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monobutyl ether, propylene glycol monophenyl ether, ethyl acetate, butyl acetate, pentyl acetate, hexyl acetate, and cyclohexanol acetate. These may be used alone or in combination of two or more.

[0077] The content of the solvent in the photosensitive conductive paste may be 3 wt% or more, and may be 5 wt% or more. The content of the solvent in the photosensitive conductive paste may be 20 wt% or less, and may be 15 wt% or less.

[0078] <Metal resinate> The photosensitive conductive paste may contain a metal resinate. This resinate is a metal resinate containing a metal having a melting point higher than the melting point of the conductive powder. Examples of the metal contained in the metal resinate include Rh, Ni, Cu, Mn, Zr, etc. Examples of such metal resinates include metal octylates, naphthenates, 2-ethylhexane salts, sulfonates, metal mercaptides, and alkoxy metal compounds.

[0079] <Common material> The photosensitive conductive paste may contain a common material (non-conductive metal oxide), but from the viewpoints of improving the resolution during photolithography patterning and reducing the electrical resistance, the lower the content, the more preferable. The content of the common material may be 3.0% by weight or less, 1.0% by weight or less, or 0% by weight with respect to the photosensitive conductive paste.

[0080] (Method for manufacturing a multilayer electronic component) Next, a method for manufacturing the multilayer electronic component 10 will be described. The method for manufacturing the multilayer electronic component 10 includes a step of laminating a photosensitive conductive paste on an insulating layer 40, a step of sintering the photosensitive conductive paste and the insulating layer 40 at a firing temperature of 800°C or higher, forming a coil 5 (internal electrode) from the photosensitive conductive paste, forming a body 4 from the insulating layer 40, and providing the coil 5 in the body 4.

[0081] According to the above manufacturing method, the shrinkage behavior of the photosensitive conductive paste during firing can be made to correspond to the shrinkage behavior of the body material. Therefore, suppression of delamination can be expected.

[0082] Hereinafter, an example of a method for manufacturing the multilayer electronic component 10 using the photosensitive conductive paste of the present disclosure will be specifically described.

[0083] As shown in FIG. 2, a glass paste as an insulating paste is screen-printed and dried on a support film such as a PET film, and this is repeated several times to obtain an insulating layer (glass layer) 40 with a predetermined thickness (for example, about 100 μm). In FIG. 2, the support film is omitted.

[0084] Insulating pastes such as glass paste contain an insulating inorganic component and an organic component. The glass paste contains, as the insulating inorganic component, for example, glass powder and ceramic aggregate (inorganic filler), and contains, as the organic component, for example, an acrylic polymer. As the organic component, a solvent, a dispersant, an antifoaming agent, etc. may be contained in addition.

[0085] The type of glass powder contained in the insulating paste is not particularly limited. For example, SiO2 - B2O3 - K2O - based glass containing SiO2, B2O3, and K2O in a predetermined ratio can be used. Two or more types of glass powder may be mixed and used. The average particle size of the glass powder is not particularly limited, but it may be 0.1 μm or more and 5.0 μm or less.

[0086] The type of ceramic aggregate contained in the insulating paste is not particularly limited. For example, alumina can be used. Two or more types of ceramic aggregate may be mixed and used. The average particle size of the ceramic aggregate is not particularly limited, but it may be 0.1 μm or more and 5.0 μm or less.

[0087] Note that the insulating layer 40 may be produced by laminating a green sheet pre-formed into a sheet shape.

[0088] On the insulating layer 40, the photosensitive conductive paste of the present disclosure is screen-printed so as to have a film thickness of about 5 μm or more and 20 μm or less, dried, and then selectively exposed and developed to form the first-layer coil wiring 2.

[0089] From above the first-layer coil wiring 2, glass paste is screen-printed over the entire surface to a film thickness of about 10 to 20 μm and dried. Subsequently, via holes 3 are formed at predetermined locations of the insulating layer 40 formed on the first-layer coil wiring 2. The via holes 3 are formed, for example, by laser processing, pattern printing, or, when the insulating paste has photolithography characteristics, by a patterning method.

[0090] Again, the photosensitive conductive paste of the present disclosure is screen-printed over the entire surface to a film thickness of about 5 μm or more and 10 μm or less, dried, and then selectively exposed and developed to form the second-layer coil wiring 2.

[0091] The lamination of the insulating layer 40 and the coil wiring 2 is repeated until the desired number of layers is obtained.

[0092] Furthermore, the glass paste is screen-printed and dried over the entire surface the required number of times to form the insulating layer 40 on the topmost layer coil wiring 2. As a result, a laminated structure is obtained in which the coil wiring 2 is interconnected between layers via the via holes 3.

[0093] The obtained laminated structure is divided into chip shapes using a dicing saw, and then the support film such as a PET film is separated. Thereafter, it is fired at a temperature of 800 °C or higher. By this firing, the photosensitive conductive paste is sintered to form the coil 5. Also, the insulating layer 40 is sintered to form the base body 4.

[0094] The first external electrode 6a and the second external electrode 6b are formed on the fired laminate. Furthermore, a plating layer having a single-layer or laminated structure may be deposited on the outer surfaces of the first external electrode 6a and the second external electrode 6b by an electrolytic plating method, an electroless plating method, or the like.

[0095] As described above, the laminated electronic component 10 shown in FIG. 1 is obtained.

[0096] Note that the present disclosure is not limited to the above-described embodiments, and design changes can be made without departing from the gist of the present disclosure.

Example

[0097] Hereinafter, the present disclosure will be described more specifically with reference to examples. However, the present disclosure is not limited by the following examples, and it is of course possible to appropriately modify and implement it within the scope applicable to the gist of the foregoing and following descriptions, and all of them are included in the technical scope of the present disclosure.

[0098] [Examples 1 to 6] (1) Preparation of photosensitive resin By blending each raw material in the proportions shown in Table 1 and mixing them thoroughly, photosensitive resins A to F containing an organic component and a solvent were obtained. As the photosensitive monomer, dipentaerythritol hexa(meth)acrylate was used alone. As the alkali-soluble polymer, an acrylic polymer (specific alkali-soluble polymer) having a carboxy group in the side chain and containing an easily detachable polymerization unit was used.

[0099]

Table 1

[0100] The ratio (N1 / N) of the number N1 of easily detachable polymerization units (units derived from methyl methacrylate monomer) in the acrylic polymer used as the specific alkali-soluble polymer to the total number N of all polymerization units constituting the acrylic copolymer is shown in Table 2.

[0101]

Table 2

[0102] The ratio (Wm / Wp) of the blending weight Wm of the photosensitive monomer to the blending weight Wp of the specific alkali-soluble polymers a to d in the photosensitive resins A to F is shown in Table 3.

[0103]

Table 3

[0104] (2) Preparation of photosensitive conductive paste 80% by weight of conductive powder (Ag powder), 18% by weight of each photosensitive resin (A - F), and 2% by weight of a dispersant were blended and thoroughly mixed with a three - roll mill to obtain a photosensitive conductive paste for internal electrode formation. Using each of the photosensitive resins A - F, the photosensitive conductive pastes of Examples 1 - 6 were prepared respectively.

[0105] [Evaluation] (1) Weight loss rate Each component other than the solvent and defoaming agent was mixed at the same ratio as the photosensitive resins A - F shown in Tables 1 and 3 respectively to obtain an organic component. This organic component was irradiated with ultraviolet light to obtain a cured product. Using a thermogravimetric analyzer, in an oxygen atmosphere, ΔTG at 300 °C and 400 °C of each cured product, and the temperature T Δ100 when 100% weight loss occurred were measured.

[0106] (2) Preparation and measurement of specific resistance evaluation samples After the photosensitive conductive pastes prepared in Examples 1 - 6 were screen - printed and dried on an alumina substrate with a film thickness of 10 μm or more and 20 μm or less, exposure treatment was performed through a photomask having a wiring pattern, and development was carried out with an alkaline aqueous solution to form a wiring pattern. The formed wiring pattern was fired at 900 °C for 60 minutes to fabricate electrode wiring for resistance measurement. The resistance value, line width, line length, and film thickness of the obtained wiring samples were measured. From the calculated volume of the wiring, the specific resistance value was calculated based on the Ag volume. A specific resistance value of 2.2 μΩ·cm or less was rated A (qualified, good), and those exceeding 2.2 μΩ·cm were rated B (unqualified).

[0107] (3) Preparation and measurement of fired shrinkage rate evaluation samples The photosensitive conductive paste prepared by the above method was printed on a smooth substrate, dried, and then exposed through a photomask having a wiring pattern, and developed with an aqueous alkali solution to form a wiring pattern. The volume of the wiring pattern of the obtained paste was calculated using a laser displacement meter. Next, these dot patterns were heat-treated at 700 °C. The volume of the wiring pattern of the heat-treated sample was calculated again using a laser displacement meter. Based on the volume values before and after the heat treatment, the percentage reduction in volume due to the heat treatment was calculated, and this value was defined as the firing shrinkage rate.

[0108] In the heat treatment at 700 °C, the photosensitive resins A to F are 100% decomposed. Typically, the shrinkage of the base material containing no organic components is small. Therefore, the fact that the shrinkage rate of the photosensitive conductive paste (i.e., the internal electrode) after heat treatment at 700 °C is small also indicates that delamination is suppressed.

[0109] The level with a shrinkage rate at 700 °C of less than 30% was designated as A (qualified, better), the level with a shrinkage rate of 30% or more and less than 40% was designated as B (qualified, good), and the level with a shrinkage rate of 40% or more was designated as C (unqualified).

[0110] (4) Patterning property (resolution) After the photosensitive conductive paste was screen-printed on an alumina substrate, it was dried at 60 °C for 30 minutes to form a photosensitive conductive paste film with a film thickness of 10 μm. Next, the substrate was irradiated with light from an ultra-high pressure mercury lamp (manufactured byUSHIO INC.) through a photomask with a linear pattern of L / S = 25 / 25 μm at 1000 mJ / cm 2 (405 nm) to perform mask exposure on the photosensitive conductive paste film. Thereafter, development treatment was performed with an aqueous triethanolamine solution. Those that could be formed without residue and line skipping were designated as A (qualified), and those with line skipping were designated as B (unqualified).

[0111] The evaluation results are shown in Table 4. Table 4 also shows the ratio (N1 / N) and the ratio (Wm / Wp).

[0112]

Table 4

[0113] The photosensitive conductive paste used in the examples satisfies the above conditions A and B, has a small firing shrinkage rate at a firing temperature of 700 °C, and can be expected to suppress delamination. Further, the photosensitive conductive paste used in the examples satisfies the above condition C, and the shrinkage of the photosensitive conductive paste proceeds gently until the degreasing is completed, and suppression of delamination can be further expected.

[0114] In addition, since the photosensitive conductive paste used in the examples does not contain a co-material, it has a small specific resistance after firing and good patterning properties. Therefore, it can be seen that the electrical resistance is low and the resolution during photolithographic patterning is improved. That is, according to the photosensitive conductive paste used in the examples, it is possible to obtain an internal electrode in which delamination is suppressed, the electrical resistance is low, and the resolution during photolithographic patterning is excellent.

[0115] On the other hand, a photosensitive conductive paste that does not satisfy the above condition A and has a weight loss rate of 50% or more at 300 °C is expected to have an excessively large shrinkage rate of the photosensitive conductive paste up to 300 °C, does not correspond to the shrinkage behavior of the green body material, and suppression of delamination cannot be expected. A photosensitive conductive paste that does not satisfy the above condition B and has a weight loss rate of less than 100% at 700 °C is expected to have a residue of the organic component trapped in the green body 4, so suppression of delamination cannot be expected either.

[0116] <1> containing a conductive powder, an organic component, and a solvent, The organic component includes an alkali-soluble polymer, a photosensitive monomer, and a photopolymerization initiator, and the photosensitive conductive paste in which the cured product of the organic component satisfies the following conditions A and B in terms of thermal decomposability in an oxygen atmosphere. (Condition A) In thermogravimetric measurement, the weight loss rate at 300 °C is less than 50%. (Condition B) In thermogravimetric measurement, the weight loss rate at 700 °C is 100%. <2> The photosensitive conductive paste according to <1>, wherein the weight loss rate at 300 °C in the condition A is less than 30%. <3> The photosensitive conductive paste according to <1> or <2>, wherein the weight loss rate at 600 °C in the condition B is 100%. <4> The photosensitive conductive paste according to any one of <1> to <3>, wherein the thermal decomposability of the cured product in an oxygen atmosphere satisfies the following condition C. (Condition C) In thermogravimetric measurement, the change in the weight loss rate in the range of 300 °C or more and 400 °C or less is 70% or less. <5> The alkali-soluble polymer contains a copolymer containing an easily detachable polymerization unit showing a main-chain cleavage type decomposability during thermal decomposition. The photosensitive conductive paste according to any one of <1> to <4>, wherein the ratio of the number of the easily detachable polymerization units to the total number of polymerization units constituting the copolymer is 0.2 or more and 0.6 or less. <6> The photosensitive conductive paste according to <5>, wherein the ratio (Wm / Wp) of the blending weight Wm of the photosensitive monomer to the blending weight Wp of the alkali-soluble polymer is 0.2 or more and 0.9 or less. <7> The photosensitive conductive paste according to any one of <1> to <6>, wherein the conductive powder is silver powder. <8> The photosensitive conductive paste according to <7>, wherein the average particle diameter D50 of the silver powder is 0.5 μm or more and 5.0 m or less. <9> A step of laminating the photosensitive conductive paste according to any one of <1> to <8> on an insulating layer; A step of sintering the photosensitive conductive paste and the insulating layer at a firing temperature of 800 °C or more, and Forming an internal electrode from the photosensitive conductive paste, Form a body from the insulating layer, A method of manufacturing a multilayer electronic component, comprising providing the internal electrode within the body. <10> A body containing borosilicate glass and an inorganic filler, An internal electrode provided within the body and being a sintered body of the photosensitive conductive paste according to any one of <1> to <8>. A multilayer electronic component comprising the same.

Explanation of reference numerals

[0117] 2 Coil wiring 3 Via hole 4 Body 5 Coil 5a First end 5b Second end 6a First external electrode 6b Second external electrode 10 Multilayer electronic component 40 Insulating layer 41, 42 First end face, second end face 43, 44 First side face, second side face 45 Bottom face 46 Top face

Claims

1. A photosensitive conductive paste comprising conductive powder, an organic component, and a solvent, wherein the organic component includes an alkali-soluble polymer, a photosensitive monomer, and a photoinitiator, and the cured product of the organic component satisfies the following Conditions A and B in an oxygen atmosphere. (Condition A) In thermogravimetric measurement, the weight loss rate at 300 °C is less than 50%. (Condition B) In thermogravimetric measurement, the weight loss rate at 700 °C is 100%.

2. The photosensitive conductive paste according to Claim 1, wherein the weight loss rate at 300 °C in Condition A is less than 30%.

3. The photosensitive conductive paste according to Claim 1 or 2, wherein the weight loss rate at 600 °C in Condition B is 100%.

4. The photosensitive conductive paste according to Claim 1 or 2, wherein the thermal decomposability of the cured product in an oxygen atmosphere satisfies the following Condition C. (Condition C) In thermogravimetric measurement, the change in the weight loss rate in the range of 300 °C or more and 400 °C or less is 70% or less.

5. The alkali-soluble polymer includes a copolymer containing an easily detachable polymerization unit that exhibits main-chain cleavage type decomposability during thermal decomposition, The photosensitive conductive paste according to Claim 1 or 2, wherein the ratio of the number of the easily detachable polymerization units to the total number of polymerization units constituting the copolymer is 0.2 or more and 0.6 or less.

6. The photosensitive conductive paste according to Claim 5, wherein the ratio (Wm / Wp) of the blending weight Wm of the photosensitive monomer to the blending weight Wp of the alkali-soluble polymer is 0.2 or more and 0.9 or less.

7. The photosensitive conductive paste according to Claim 1 or 2, wherein the conductive powder is silver powder.

8. The photosensitive conductive paste according to Claim 7, wherein the average particle size D50 of the silver powder is 0.5 μm or more and 5.0 m or less.

9. A method for manufacturing a multilayer electronic component, comprising the steps of laminating the photosensitive conductive paste according to Claim 1 or 2 on an insulating layer, sintering the photosensitive conductive paste and the insulating layer at a firing temperature of 800 °C or more, forming an internal electrode from the photosensitive conductive paste, forming a body from the insulating layer, and providing the internal electrode in the body.

10. A multilayer electronic component comprising a body containing borosilicate glass and an inorganic filler, and an internal electrode provided in the body and being a sintered body of the photosensitive conductive paste according to Claim 1 or 2.

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