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

Abstract

This invention provides a photosensitive conductive paste with controlled shrinkage behavior during firing, a method for manufacturing multilayer electronic components, and multilayer electronic components. The photosensitive conductive paste of this invention contains conductive powder, organic components, and a solvent. The organic components include an alkali-soluble polymer, a photosensitive monomer, and a photopolymerization initiator. The cured organic components exhibit thermal decomposition in an oxygen environment satisfying the following conditions A and B: (Condition A) In a thermogravimetric determination, the weight loss rate at 300°C is less than 50%. (Condition B) In a thermogravimetric determination, the weight loss rate at 700°C is 100%.

Description

Technical Field

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

[0002] In recent years, multilayer electronic components such as multilayer ceramic circuit boards have been manufactured using photosensitive conductive pastes to form internal electrodes. The internal electrodes are formed by patterning the photosensitive conductive paste and then firing it, thereby sintering the conductive powder contained in the paste. Examples of photosensitive conductive pastes used in multilayer electronic components include those disclosed in Japanese Patent Application Publication No. 2002-169274 (Patent Document 1) and Japanese Patent Application Publication No. 2007-18884 (Patent Document 2).

[0003] Japanese Patent Application Laid-Open No. 2002-169274 discloses a photosensitive conductive paste containing, as main components, 40-80 wt% of conductive powder, 3-20 wt% of a photopolymerizable compound, up to 10 wt% of a photopolymerization initiator, and 0.3-2.5 wt% of one or more non-conductive metal oxides. Non-conductive metal oxides are often referred to as "common materials." The inclusion of these common materials in Japanese Patent Application Laid-Open No. 2002-169274 reduces firing shrinkage of internal electrodes.

[0004] Japanese Patent Application Laid-Open No. 2007-18884 discloses a photosensitive conductive paste containing a first conductive powder obtained by atomization with an average particle size of 5 μm or less and a second conductive powder obtained by a wet reduction method with an average particle size of 0.2 to 2.0 μm, in a weight ratio within the range of 20 / 80 ≤ (first conductive powder / second conductive powder) ≤ 80 / 20. In Japanese Patent Application Laid-Open No. 2007-18884, the inclusion of the first conductive powder with a relatively large average particle size reduces firing shrinkage of the internal electrodes. Prior Art Literature Patent Literature

[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

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

[0007] Therefore, the present disclosure aims to provide a photosensitive conductive paste with controlled shrinkage during firing. Furthermore, the present disclosure aims to provide a method for manufacturing a build-up electronic component using the photosensitive conductive paste and a build-up electronic component.

[0008] In order to solve the above problems, a photosensitive conductive paste according to one aspect of the present disclosure contains conductive powder, an organic component and a solvent. The organic component comprises an alkali-soluble polymer, a photosensitive monomer and a photopolymerization initiator. The cured product of the organic component has thermal decomposition properties in an oxygen environment that satisfy the following conditions A and B. (Condition A) In thermogravimetric measurement, the weight loss at 300°C was less than 50%. (Condition B) In thermogravimetric measurement, the weight loss rate at 700°C was 100%.

[0009] According to the above aspect, since the shrinkage behavior of the photosensitive conductive paste during firing is controlled, when used as an internal electrode of a laminated electronic component, the shrinkage behavior of the main material during firing is minimized, thereby suppressing delamination. Furthermore, since no common materials are required and the conductive powder does not need to be increased in particle size, the resolution during photolithographic patterning is improved, and the resistance of the resulting internal electrodes can be reduced.

[0010] According to the photosensitive conductive paste disclosed herein, the shrinkage behavior of the photosensitive conductive paste during firing can be controlled. Simple diagram description

[0011] FIG1 is a perspective view schematically showing a multilayer electronic component. FIG2 is an exploded perspective view schematically showing a multilayer electronic component. Implementation Method

[0012] The following describes in detail a photosensitive conductive paste, a method for manufacturing a laminated electronic component, and a laminated electronic component, which are one aspect of the present disclosure, using illustrated embodiments. The drawings contain some schematic elements and may not reflect actual dimensions or ratios.

[0013] (Overall structure of multilayer electronic components) Figure 1 is a schematic perspective view of a multilayer electronic component. Figure 2 is a schematic exploded perspective view of a multilayer electronic component. In Figure 1, the main body is depicted as transparent to facilitate understanding of the structure, but translucent or opaque design is also possible. In Figure 1, the coil is omitted to facilitate understanding of the structure. In Figure 2, the external electrodes are omitted for clarity.

[0014] In the following, a multilayer coil component is used as an example to explain a multilayer electronic component. However, the multilayer electronic component disclosed herein is not limited to multilayer coil components and can be applied to various multilayer electronic components such as multilayer capacitor components and multilayer LC composite components.

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

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

[0017] The main body 4 is composed of a plurality of laminated insulating layers 40. The insulating material of the insulating layer 40 is not particularly limited, but includes, for example, borosilicate glass and inorganic fillers. Examples of the inorganic filler are 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 a layer extending in the XY plane. In the insulating layer 40 located between adjacent coil wirings 2 among the plurality of coil wirings 2 described later, a via hole 3 is provided at a position connecting the adjacent coil wirings 2. The via hole 3 penetrates the insulating layer 40 in the thickness direction (Z direction). The term "parallel" in this case is not limited to a strict parallel relationship, but also includes a substantially parallel relationship taking into account the actual deviation range. In addition, the main body 4 may sometimes have unclear interfaces between the plurality of insulating layers 40 due to firing, etc.

[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 primarily composed of these materials. In this embodiment, the first external electrode 6a is continuously provided over the entire first end surface 41 of the main body 4, the end of the first side surface 43 on the first end surface 41 side, the end of the second side surface 44 on the first end surface 41 side, the end of the bottom surface 45 on the first end surface 41 side, and the end of the top surface 46 on the first end surface 41 side. Furthermore, the second external electrode 6b is continuously provided over the entire second end surface 42 of the main body 4, the end of the first side surface 43 on the second end surface 42 side, the end of the second side surface 44 on the second end surface 42 side, the end of the bottom surface 45 on the second end surface 42 side, and the end of the top surface 46 on the second end surface 42 side. In short, the first external electrode 6a and the second external electrode 6b are each five-sided electrodes. However, this is not limiting; the first external electrode 6a may be, for example, an L-shaped electrode continuously provided over a portion of the first end surface 41 and a portion of the bottom surface 45. Likewise, the second external electrode 6 b may be, for example, an L-shaped electrode continuously provided on a portion of the second end surface 42 and a portion of the bottom surface 45 .

[0019] The coil 5 is a sintered body of a photosensitive conductive paste containing conductive powders such as Ag and Cu. The coil 5 is wound helically along the lamination direction of the insulating layer 40. The first end 5a of the coil 5 is exposed from the first end surface 41 of the main body 4 and connected to the first external electrode 6a. The second end 5b of the coil 5 is exposed from the second end surface 42 of the main body 4 and connected to the second external electrode 6b.

[0020] Coil 5 is rectangular when viewed from the axial direction, but this shape is not limited to this. The shape of coil 5 can be, for example, circular, elliptical, rectangular, or other polygonal. Coil 5 is wound axially, parallel to the Z direction. The axis of coil 5 refers to the central axis of the coil's helical shape.

[0021] The coil 5 comprises a plurality of coil wires 2 stacked in the axial direction and a connecting wire (not shown) extending in the axial direction and connecting axially adjacent coil wires 2. The plurality of coil wires 2 are wound along a plane, arranged in the axial direction, electrically connected in series, and simultaneously form a spiral.

[0022] The coil wiring 2 is wound around the main surface (XY plane) of the insulating layer 40, which is perpendicular to the axial direction. The number of turns of the coil wiring 2 is less than one, but may be one or more. The connecting wiring is provided within the through-hole 3 of the insulating layer 40, penetrating the insulating layer 40 in the thickness direction (Z direction). Furthermore, adjacent coil wirings 2 in the stacking direction are electrically connected in series via the connecting wiring.

[0023] In this multilayer electronic component 10, multiple insulating layers 40 and patterned layers of photosensitive conductive paste are alternately stacked, and the multiple insulating layers 40 and the multiple patterned layers of photosensitive conductive paste are sintered. This creates a body 4 formed by the multiple insulating layers 40, and a coil 5 formed by the multiple patterned layers of photosensitive conductive paste.

[0024] (Detailed composition of photosensitive conductive paste) Next, the detailed structure of the photosensitive conductive paste used to form coil 5 will be described. While the following describes the photosensitive conductive paste used to form coil 5 of a multilayer electronic component 10, which is a multilayer coil component, the photosensitive conductive paste of this disclosure is not limited to this application and can be used to form internal electrodes in various multilayer electronic components, such as multilayer capacitor components and multilayer LC composite components. For example, in the case of multilayer capacitor components, the photosensitive conductive paste of this disclosure can be used to form capacitor electrodes.

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

[0026] <Conductive Powder> The conductive powder is sintered during firing, forming the conductor of coil 5. The type of conductive powder is not particularly limited, but silver (Ag) or copper (Cu) can be used to reduce the resistance of the resulting coil 5. The conductive powder content relative to the photosensitive conductive paste can be 65% to 90% by weight. To minimize shrinkage after firing, the conductive powder content can be 70% to 85% by weight.

[0027] To ensure fine coil 5 patterns, the conductive powder should have an average particle size D50 (median diameter) of 0.5 μm to 5.0 μm. The average particle size D50 is the 50% diameter in a volume-based particle size distribution, as measured using a laser diffraction particle size analyzer (e.g., MT3000 manufactured by Microtrac Bel Co., Ltd.).

[0028] The conductive powder can be silver (Ag) powder. The average particle size D50 of the Ag powder can be between 0.5 μm and 5.0 μm. The conductive powder can particularly be atomized Ag powder produced by an atomization method. Compared to Ag powder produced by a wet reduction method, atomized Ag powder has a larger crystallite diameter and contains fewer organic impurities. This further reduces the resistance of the resulting coil 5.

[0029] <Organic ingredients> The organic component contains at least an alkali-soluble polymer, a photosensitive monomer, and a photopolymerization initiator. The organic component content can be 5% or more by weight of the photosensitive conductive paste, or 8% or more by weight. The organic component content can be 20% or less by weight of the photosensitive conductive paste, or 15% or less by weight.

[0030] Organic components decompose upon heating. This weight loss (in this case, equivalent to a volume loss) of the organic components causes coil 5 to shrink. However, if the shrinkage behavior of the photosensitive conductive paste during firing matches that of the main body material, delamination, a structural defect that can occur between the resulting coil 5 and main body 4, can be suppressed.

[0031] The host material typically consists of borosilicate glass, which typically has a softening point exceeding 700°C. When the glass component softens by heating above 700°C, the host material undergoes rapid sintering and thermal contraction. Specifically, the host material exhibits minimal shrinkage until the glass component softens, but then rapidly contracts after softening.

[0032] The cured product of the organic component used in the photosensitive conductive paste of the present disclosure (hereinafter sometimes simply referred to as “cured product”) has thermal decomposition properties in an oxygen environment that satisfy the following conditions A and B. (Condition A) In thermogravimetric measurement, the weight loss at 300°C was less than 50%. (Condition B) In thermogravimetric measurement, the weight loss rate at 700°C was 100%.

[0033] Condition A indicates that the degree of thermal decomposition of the cured product is minimal up to 300°C. This means that the shrinkage of the photosensitive conductive paste is minimal up to 300°C. As mentioned above, the shrinkage of the host material is also minimal up to 300°C. In other words, the shrinkage of both the photosensitive conductive paste and the host material is minimal up to 300°C, and their shrinkage behaviors correspond. The weight loss rate (hereinafter sometimes referred to as ΔTG) of the cured product at 300°C may be less than 40%, less than 35%, or less than 30%.

[0034] However, the thermal decomposition of the organic components contained in the photosensitive conductive paste must be completed before the glass component of the host material begins to soften. If these organic components remain when the glass component of the host material begins to soften, the molten glass component will capture the decomposed and vaporized organic components. The gaseous organic components remaining inside the multilayer electronic component 10 will remain in the host material as cavities, causing structural defects.

[0035] Condition B indicates that the cured product is completely decomposed before 700°C. This means that the organic components in the photosensitive conductive paste are completely decomposed before 700°C. If the temperature exceeds 700°C, the glass component in the main material begins to soften, as described above. By completing the decomposition of the cured product before 700°C, the capture of vaporized organic components can be suppressed. The weight loss rate of the cured product at 600°C can be 100%.

[0036] By satisfying both conditions A and B, the organic components contained in the photosensitive conductive paste gradually decompose up to 300°C, and complete decomposition (weight loss rate of 100%) when the temperature exceeds 300°C and reaches 700°C. This means that the shrinkage behavior of the host material during firing matches that of the photosensitive conductive paste, thus suppressing delamination.

[0037] The cured product is obtained by mixing and curing the organic components in the same proportions as those used in the photosensitive conductive paste. The cured product can be obtained by curing a mixture of a photosensitive monomer, an alkali-soluble polymer, and a photopolymerization initiator in the same proportions as those used in the photosensitive conductive paste. This is because the amount of other organic components (typically additives described below) added is small, minimizing their impact on ΔTG.

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

[0039] The thermal decomposition property of the cured product in an oxygen environment may further satisfy the following condition C. (Condition C) In thermogravimetric measurement, the change in weight loss rate within the range of 300° C. to 400° C. is 70% or less.

[0040] Condition C shows that the weight of the cured product decreases at a relatively slow rate even after temperatures exceed 300°C. This means that the photosensitive conductive paste shrinks slowly until degreasing is complete. This shrinkage behavior closely matches that of the host material during firing, further reducing delamination.

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

[0042] Alkali-soluble polymers The alkali-soluble polymer is neutralized and dissolved by the alkaline compound. During development using an alkaline developer, for example, the alkali-soluble polymer is removed along with uncured photosensitive monomer and conductive powder. Meanwhile, when the photosensitive monomer is polymerized by active energy rays, the alkali-soluble polymer present nearby forms a film together with the polymerized photosensitive monomer, forming, for example, a portion of the internal electrode pattern. This improves the adhesion of the internal electrode pattern to the insulating layer.

[0043] The content of the alkali-soluble polymer may be 30% by weight or more, or 35% by weight or more, relative to the organic component. The content of the alkali-soluble polymer may be 60% by weight or less, or 55% by weight or less, relative to the organic component.

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

[0045] Alkali-soluble polymers have at least one acid group in their side chains. Typical examples of acid groups include carboxyl groups. Alkali-soluble polymers contain, as their main chains, a polymer chain having at least one of, for example, a carbon-carbon bond, an ether bond, a urea bond, an ester bond, or an urethane bond. From the perspective of transparency, the main chains of alkali-soluble polymers may include polymer chains having carbon-carbon bonds.

[0046] Alkali-soluble polymers having at least one carboxyl group in a side chain and a polymer chain with carbon-carbon bonds as a main chain can be obtained, for example, by copolymerizing an unsaturated carboxylic acid with an ethylenically unsaturated compound. Typical examples of alkali-soluble polymers include carboxyl-containing acrylic polymers.

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

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

[0049] The carboxyl groups of the alkali-soluble polymer can be introduced after the main chain is formed. For example, the carboxyl groups of the alkali-soluble polymer can be introduced by reacting a compound having an epoxy group in a side chain and having the above-mentioned polymer chain with an unsaturated monocarboxylic acid, followed by further reaction 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 can be introduced, for example, by adding a monomer having a polymerizable functional group (typically an epoxy group) that is reactive with a carboxyl group located on a side chain.

[0051] The alkali-soluble polymer may particularly include a copolymer containing easily releasable polymerized units that exhibit main-chain cleavage-type decomposition during thermal decomposition. This facilitates control of the thermal decomposition (shrinkage) of the cured product, making it easier to obtain a photosensitive conductive paste that satisfies the aforementioned conditions A and B (and further condition C, the same applies hereinafter).

[0052] The weight ratio of the copolymer containing the easily releasable polymerized unit in the total amount of the alkali-soluble polymer may be 50% by weight or more, 80% by weight or more, or 100% by weight.

[0053] Representative examples of the easily releasable polymerized unit include a unit derived from an ethylene monomer (chemical formula (1) below), a unit derived from a propylene monomer (chemical formula (2) below), a unit derived from an isobutylene monomer (chemical formula (3) below), a unit derived from a styrene monomer (chemical formula (4) below), a unit derived from a methyl methacrylate monomer (chemical formula (5) below), a unit derived from a tetrafluoroethylene monomer (chemical formula (6) below), and a unit derived from an α-methylstyrene monomer (chemical formula (7) below). These units may be contained in the above-mentioned copolymer alone or in combination of two or more.

[0054]

[0055]

[0056]

[0057]

[0058]

[0059]

[0060]

[0061] The ratio (N1 / N) of the number of easily releasable polymerized units N1 to the total number of polymerized units N constituting the copolymer can be 0.2 or greater and 0.6 or less. This makes it easier to obtain a photosensitive conductive paste that meets the above-mentioned conditions A and B. Hereinafter, an alkali-soluble polymer having the above-mentioned ratio (N1 / N) of 0.2 or greater and 0.6 or less may be referred to as a "specific alkali-soluble polymer." The ratio (N1 / N) can 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 dissociable polymerizable unit (hereinafter referred to as the easily dissociable monomer) by the total charged molar number of the plurality of raw material monomers used to produce the specific alkali-soluble polymer.

[0063] The easily releasable monomer is a monomer that forms an easily releasable polymerized unit (e.g., the unit represented by the above chemical formulas (1) to (7)) during polymerization. Examples of the easily releasable 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 the photopolymerization initiator to generate monomer free radicals, which polymerize to form a polymer.

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

[0067] There are no limitations on the photosensitive monomer as long as it has at least one radically reactive group. Examples of the radically reactive group include at least one selected from the group consisting of acrylamide, acryl, methacryl, allyl, vinyl, styryl, and mercapto. The photosensitive monomer may have at least one (meth)acryl group as a radically reactive group. "(Meth)acryl" refers to an acryl and / or methacryl group.

[0068] Examples of the photosensitive monomer 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, and ethoxylated nonylphenol (meth)acrylate; and tripropylene glycol di(meth)acrylate, isocyanuric acid EO-modified diacrylate, 1,3-butanediol di(meth)acrylate, and 1,4-butanediol di(meth)acrylate. Difunctional (meth)acrylate monomers such as 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; glycerol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, propoxylated glycerol tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, Ethoxylated pentaerythritol tri(meth)acrylate, tris(2-hydroxyethyl) isocyanate tri(meth)acrylate, caprolactone-modified tris(2-hydroxyethyl) isocyanate tri(meth)acrylate, hexanediol tri(meth)acrylate, tripropylene glycol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, EO-modified trimethylolpropane tri(meth)acrylate and other trifunctional (meth)acrylate monomers; pentaerythritol tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, tripentaerythritol tetra(meth)acrylate, di(trimethylolpropane) tetra(meth)acrylate Tetrafunctional (meth)acrylate monomers such as esters, ethoxylated pentaerythritol tetra(meth)acrylate; pentafunctional (meth)acrylate monomers such as dipentaerythritol penta(meth)acrylate, tripentaerythritol penta(meth)acrylate, dipentaerythritol monohydroxy penta(meth)acrylate; hexafunctional (meth)acrylate monomers such as dipentaerythritol hexa(meth)acrylate, caprolactone-modified dipentaerythritol hexa(meth)acrylate, tripentaerythritol hexa(meth)acrylate; heptafunctional or higher functional (meth)acrylate monomers such as tripentaerythritol hepta(meth)acrylate, tripentaerythritol octa(meth)acrylate. These monomers may be used alone or in combination of two or more.

[0069] The photosensitive monomer may be a trifunctional or higher-functional (meth)acrylate monomer, a tetrafunctional or higher-functional (meth)acrylate monomer, or a pentafunctional or higher-functional (meth)acrylate monomer. The photosensitive monomer may be dipentatritol monohydroxypenta(meth)acrylate.

[0070] The ratio of the blend weight Wm of the photosensitive monomer to the blend weight Wp of the alkali-soluble polymer (Wm / Wp) can be 0.2 or more and 0.9 or less. This makes it particularly easy to obtain a photosensitive conductive paste that satisfies the above-mentioned conditions A and B.

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

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

[0073] Photopolymerization Initiator Photopolymerization initiators generate highly reactive free radicals in response to active energy rays. These free radicals add to the photosensitive monomer, initiating a reaction in the photosensitive monomer. The free radicals form in a chain reaction, eventually producing a polymer derived from the photosensitive monomer. The content of the photopolymerization initiator can be 3% or more by weight relative to the organic component, or 5% or more by weight. The content of the photopolymerization initiator can be 10% or less by weight relative to the organic component, or 8% or less by weight.

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

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

[0076] <Solvent> The solvent is not particularly limited, and examples thereof 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, amyl 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% by weight or more, or 5% by weight or more. The content of the solvent in the photosensitive conductive paste may be 20% by weight or less, or 15% by weight or less.

[0078] <Metal Resinate> The photosensitive conductive paste may contain a metal resinate. This resinate contains a metal with a higher melting point than the conductive powder. Examples of metals contained in the metal resinate include Rh, Ni, Cu, Mn, and Zr. Examples of such metal resinates include metal octoates, naphthenates, 2-ethylhexane salts, sulfonates, metal thiolates, and metal alkoxides.

[0079] <Common Materials> Photosensitive conductive pastes may contain a co-material (non-conductive metal oxide), but the lower the content, the better, from the perspective of improving resolution during photolithographic patterning and reducing electrical resistance. The co-material content can be 3.0% by weight or less, 1.0% by weight or less, or even 0% by weight, relative to the total weight of the photosensitive conductive paste.

[0080] (Manufacturing method of multilayer electronic components) Next, a method for manufacturing the multilayer electronic component 10 is described. The method for manufacturing the multilayer electronic component 10 includes: The step of laminating the photosensitive conductive paste on the insulating layer 40; and Step of sintering the photosensitive conductive paste and the insulating layer 40 at a firing temperature of 800 ℃ or more; The coil 5 (internal electrode) is formed by photosensitive conductive paste. The main body 4 is formed by the insulating layer 40, A coil 5 is provided within the main body 4 .

[0081] According to the above-mentioned manufacturing method, the shrinkage behavior of the photosensitive conductive paste during firing can be matched to the shrinkage behavior of the host material. Therefore, delamination can be expected to be suppressed.

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

[0083] As shown in FIG2 , a glass paste serving as an insulating paste is screen-printed onto a support film such as a PET film and dried. This process is repeated several times to form an insulating layer (glass layer) 40 of a predetermined thickness (e.g., approximately 100 μm). The support film is omitted in FIG2 .

[0084] Insulating pastes such as glass paste contain insulating inorganic and organic components. Glass pastes contain, for example, glass powder and ceramic aggregate (inorganic filler) as insulating inorganic components, and, for example, acrylic polymers as organic components. They may also contain solvents, dispersants, defoaming agents, and other organic components.

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

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

[0087] Alternatively, the insulating layer 40 may be manufactured by laminating green sheets that have been pre-formed into a sheet shape.

[0088] The photosensitive conductive paste of the present disclosure is screen-printed on the insulating layer 40 to a film thickness of about 5 μm to 20 μm, dried, selectively exposed, and developed to form the first layer of coil wiring 2 .

[0089] Glass paste is screen-printed onto the entire surface of the first layer of coil wiring 2 to a thickness of approximately 10 to 20 μm and then dried. Next, through-holes 3 are formed at predetermined locations on the insulating layer 40 formed on the first layer of coil wiring 2. These through-holes 3 are formed, for example, by laser processing, pattern printing, or, if the insulating paste has photolithographic properties, by patterning.

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

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

[0092] Then, the entire surface of the glass paste is printed and dried as many times as necessary to form an insulating layer 40 on the top layer of the coil wiring 2. Thus, a laminated structure is obtained in which the coil wiring 2 is connected to each other through the through-holes 3.

[0093] The resulting laminated structure is cut into wafer shapes using a dicing machine, and the supporting film, such as PET film, is separated. The laminate is then fired at a temperature above 800°C. This firing sinters the photosensitive conductive paste, forming coil 5. Furthermore, the insulating layer 40 is sintered, forming the main body 4.

[0094] The first and second external electrodes 6a and 6b are formed on the fired laminate. Furthermore, the outer surfaces of the first and second external electrodes 6a and 6b may be coated with a single-layer or multi-layer plating layer by electroplating, electroless plating, or the like.

[0095] Through the above process, the multilayer electronic component 10 shown in FIG. 1 is obtained.

[0096] In addition, the present disclosure is not limited to the above-mentioned embodiments, and design changes can be made without departing from the scope of the present disclosure. Example

[0097] The following examples are given to illustrate the present disclosure in more detail. However, the present disclosure is not limited to the following examples and can be implemented with appropriate modifications within the scope of the above and below mentioned principles. These are all included in the technical scope of the present disclosure.

[0098] [Examples 1 to 6] (1) Preparation of photosensitive resin Photosensitive resins A to F containing an organic component and a solvent were obtained by blending the raw materials in the proportions shown in Table 1 and thoroughly mixing them. Dipentatriol hexa(meth)acrylate was used alone as the photosensitive monomer. An acrylic polymer (specific alkali-soluble polymer) having a carboxyl group in its side chain and containing an easily cleavable polymerized unit was used as the alkali-soluble polymer.

[0099] [Table 1] Element Content in photosensitive resin Specific alkali-soluble polymers a~d Total 50% by weight Photosensitive monomer (dipentatyritol hexa(meth)acrylate) Photopolymerization initiator (α-aminoalkylphenone type) 4% by weight Solvent (cyclohexanol acetate) 45% by weight defoaming agent 1% by weight

[0100] Table 2 shows the ratio (N1 / N) of the number N1 of easily releasable polymerized units (units derived from a methyl methacrylate monomer) in the acrylic polymer used as the specific alkali-soluble polymer to the total number N of polymerized units constituting the acrylic copolymer.

[0101] [Table 2] Element Number of easily releasable polymer units / total number of polymer units (N1 / N) Specific alkali-soluble polymer a 0.6 Specific alkali-soluble polymer b 0.4 Specific alkali-soluble polymer c 0.2 Specific alkali-soluble polymer d 0.0

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

[0103] [Table 3] Photosensitive resin Specific alkali-soluble polymer types Photosensitive monomer / specific alkali-soluble polymer (Wm / Wp) A a 0.2 B b 0.4 C b 0.6 D b 0.8 E c 0.3 F d 0.3

[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 mixed thoroughly using a three-roll mill to produce a photosensitive conductive paste for forming internal electrodes. Using each photosensitive resin A-F, the photosensitive conductive pastes of Examples 1-6 were prepared.

[0105] [evaluate] (1) Weight reduction rate An organic component was prepared by mixing all components except the solvent and defoaming agent in the same proportions as those for photosensitive resins A to F shown in Tables 1 and 3. This organic component was irradiated with ultraviolet light to obtain a cured product. The ΔTG of each cured product at 300°C and 400°C, as well as the temperature (T Δ100) at which the weight was reduced by 100%, were measured using a thermogravimetric analyzer in an oxygen atmosphere.

[0106] (2) Preparation and measurement of resistivity evaluation samples The photosensitive conductive paste prepared in Examples 1-6 was screen-printed onto an alumina substrate to a film thickness of 10 μm to 20 μm. After drying, the paste was exposed through a photomask with a wiring pattern and developed with an alkaline aqueous solution to form a wiring pattern. The resulting wiring pattern was fired at 900°C for 60 minutes to produce electrode wiring for resistance measurement. The resulting wiring samples were measured for resistance, line width, line length, and film thickness. The specific resistivity was calculated from the calculated wiring volume and the Ag volume. A specific resistivity of 2.2 μΩ·cm or less was rated A (pass / good), while a value exceeding 2.2 Ω·cm was rated B (fail).

[0107] (3) Preparation and measurement of firing shrinkage evaluation samples The photosensitive conductive paste prepared by the above method is printed onto a smooth substrate, dried, and then exposed through a photomask with a wiring pattern. Development is performed with an alkaline aqueous solution to form a wiring pattern. The volume of the wiring pattern in the resulting paste is calculated using a laser displacement meter. Next, this dot pattern is heat-treated at 700°C. The volume of the wiring pattern in the heat-treated sample is again calculated using a laser displacement meter. Based on the volume values ​​before and after heat treatment, the percentage of volume reduction due to heat treatment is calculated, and this value is used as the firing shrinkage ratio.

[0108] During the 700°C heat treatment, photosensitive resins A through F decompose 100%. Typically, host materials that do not contain organic components exhibit minimal shrinkage. Therefore, the low shrinkage of the photosensitive conductive paste (i.e., the internal electrodes) after heat treatment at 700°C also indicates that delamination is suppressed.

[0109] The level of shrinkage at 700°C less than 30% was rated as A (acceptable, better), the level of 30% or more but less than 40% was rated as B (acceptable, good), and the level of 40% or more was rated as C (unacceptable).

[0110] (4) Patterning (analysis) After screen-printing a photosensitive conductive paste onto an alumina substrate, the paste was dried at 60°C for 30 minutes to form a 10μm-thick film. Next, the substrate was exposed to light from an ultrahigh-pressure mercury lamp (manufactured by Ushio Inc.) at 1000mJ / cm² (405nm) through a photomask with a linear pattern of L / S = 25 / 25μm. This mask-like exposure process was then applied. The film was then developed using an aqueous triethanolamine solution. Those that can be formed without residue and skipping are rated A (qualified), and those with skipping are rated 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] Example photosensitivity resin N1 / N Wm / Wp ΔTG (%) at 300°C ΔTG (%) at 400°C Temperature when ΔTG 100% Firing shrinkage (%) Specific resistance Patternability 700°C 1 A 0.6 0.2 36 58 500 B A A 2 B 0.4 0.4 32 52 550 B A A 3 C 0.4 0.6 28 40 550 A A A 4 D 0.4 0.8 18 30 550 A Alpha A 5 E 0.2 0.3 20 32 560 A A A 6 F 0 0.3 19 35 560 A A A

[0113] The photosensitive conductive paste used in the examples met conditions A and B above, exhibiting low shrinkage upon firing at a firing temperature of 700°C, which can be expected to suppress delamination. Furthermore, the photosensitive conductive paste used in the examples met condition C above, exhibiting gradual shrinkage until degreasing was complete, which can be expected to further suppress delamination.

[0114] Furthermore, the photosensitive conductive paste used in the examples contains no common materials, resulting in a low specific resistance after firing and excellent patterning properties. This low resistance improves resolution during photolithographic patterning. In other words, the photosensitive conductive paste used in the examples can suppress delamination, produce internal electrodes with low resistance and excellent resolution during photolithographic patterning.

[0115] In contrast, for photosensitive conductive pastes that do not meet condition A and have a weight loss rate of 50% or more at 300°C, the shrinkage rate up to 300°C is expected to be excessive, inconsistent with the shrinkage behavior of the main body material, and delamination suppression cannot be expected. For photosensitive conductive pastes that do not meet condition B and have a weight loss rate of less than 100% at 700°C, residual organic components are expected to remain within the main body 4, and thus delamination suppression cannot be expected either.

[0116] <1> A photosensitive conductive paste containing conductive powder, organic components and solvent. The organic component comprises an alkali-soluble polymer, a photosensitive monomer and a photopolymerization initiator. The cured product of the organic component satisfies the following conditions A and B in terms of thermal decomposition properties in an oxygen environment. (Condition A) In thermogravimetric measurement, the weight loss at 300°C was less than 50%. (Condition B) In thermogravimetric measurement, the weight loss rate at 700°C was 100%. <2> like <1> The photosensitive conductive paste has a weight reduction rate of less than 30% at 300° C. in the condition A. <3> like <1> or <2> The photosensitive conductive paste, wherein under the condition B, has a weight reduction rate of 100% at 600°C. <4> like <1> ~ <3> The photosensitive conductive paste according to any one of the preceding claims, wherein the thermal decomposition property of the cured product in an oxygen environment satisfies the following condition C. (Condition C) In thermogravimetric measurement, the change in weight loss rate within the range of 300° C. to 400° C. is 70% or less. <5> like <1> ~ <4> The photosensitive conductive paste according to any one of the preceding claims, wherein the alkali-soluble polymer comprises: a copolymer containing an easily releasable polymerized unit exhibiting main chain cleavage-type decomposition during thermal decomposition; The ratio of the number of the easily releasable polymerized units to the total number of polymerized units constituting the copolymer is 0.2 or more and 0.6 or less. <6> like <5> In the photosensitive conductive paste, the ratio (Wm / Wp) of the blending weight Wm of the photosensitive monomer to the blending weight Wp of the alkali-soluble polymer is greater than or equal to 0.2 and less than or equal to 0.9. <7> like <1> ~ <6> The photosensitive conductive paste described in any one of the preceding claims, wherein the conductive powder is silver powder. <8> like <7> In the photosensitive conductive paste, the average particle size D50 of the silver powder is greater than or equal to 0.5 μm and less than or equal to 5.0 μm. <9> A method for manufacturing a multilayer electronic component, comprising: Will <1> ~ <8> The step of laminating the photosensitive conductive paste on the insulating layer as described in any one of the preceding claims, and The step of sintering the photosensitive conductive paste and the insulating layer at a firing temperature of 800 ℃ or above; Then, the internal electrodes are formed by the photosensitive conductive paste. The insulating layer forms a main body, The internal electrode is disposed within the body. <10> A multilayer electronic component comprising: Main body: Contains borosilicate glass and inorganic fillers, and Internal electrode: set in the main body, is <1> ~ <8> A sintered body of any one of the photosensitive conductive pastes.

[0117] 2: Coil wiring 3:Through hole 4: Subject 5: Coil 5a: First end 5b: Second end 6a: First external electrode 6b: Second external electrode 10: Multilayer electronic components 40: Insulation layer 41, 42: first end face, second end face 43, 44: first side, second side 45: Bottom 46: Top

Claims

1. A photosensitive conductive paste comprising conductive powder, an organic component, and a solvent, wherein the organic component comprises an alkali-soluble polymer, a photosensitive monomer having at least one free radical reactive group, and a photopolymerization initiator, wherein the ratio of the doping weight Wm of the photosensitive monomer to the doping weight Wp of the alkali-soluble polymer, i.e., Wm / Wp, is 0.2 or more and 0.8 or less, and the thermal decomposition property of the cured organic component in an oxygen environment satisfies the following conditions A and B: Condition A: In a thermogravimetric determination, the weight loss rate at 300°C is less than 40%; Condition B: In a thermogravimetric determination, the weight loss rate at 700°C is 100%.

2. The photosensitive conductive paste as claimed in claim 1, wherein, In condition B, the weight loss rate at 600°C is 100%.

3. The photosensitive conductive paste as claimed in claim 1, wherein, The thermal decomposition of the hardened material in an oxygen environment satisfies the following condition C: Condition C: In thermogravimetric analysis, the change in weight loss rate in the range of 300°C to 400°C is less than 70%.

4. The photosensitive conductive paste as claimed in claim 1, wherein, The alkali-soluble polymer comprises a copolymer containing easily detachable polymeric units that exhibit main-chain cracking decomposition upon thermal decomposition, wherein the number of these easily detachable polymeric units accounts for 0.2 or more and 0.6 or less of the total number of polymeric units constituting the copolymer.

5. The photosensitive conductive paste as claimed in claim 1, wherein, The conductive powder is silver powder.

6. The photosensitive conductive paste as claimed in claim 5, wherein, The average particle size D50 of this silver powder is greater than 0.5 μm and less than 5.0 μm.

7. A method for manufacturing a multilayer electronic component, comprising: The steps include: depositing the photosensitive conductive paste of claim 1 onto an insulating layer; sintering the photosensitive conductive paste and the insulating layer at a firing temperature of 800°C or higher; and forming an internal electrode from the photosensitive conductive paste, forming a body from the insulating layer, and disposing the internal electrode within the body.

8. A multilayer electronic component comprising: a body containing borosilicate glass and inorganic filler, and an internal electrode disposed within the body, which is a sintered body of the photosensitive conductive paste of claim 1.

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