Photosensitive conductive paste, method for manufacturing multilayer electronic components, and multilayer electronic components

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 multilayer electronic component, and a multilayer electronic component.

Background Art

[0002] In recent years, multilayer electronic components such as multilayer 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 firing it. Examples of the photosensitive conductive paste used for multilayer 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 a 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 the co-materials are included.

[0004] JP-A-2007-18884 discloses a photosensitive conductive paste containing a first conductive powder having an average particle diameter of 5 μm or less obtained by an atomization method and a second conductive powder having an average particle diameter in the range of 0.2 to 2.0 μm obtained by a wet reduction method at 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 the first conductive powder having a relatively large average particle diameter is included.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2002-169274 [Patent Document 2] Japanese Patent Publication No. 2007-18884 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, it was found that even if the firing shrinkage of the internal electrodes is reduced, delamination can still occur if the shrinkage of the photosensitive conductive paste during firing does not correspond to the shrinkage of the base material.

[0007] Therefore, the object of this disclosure is to provide a photosensitive conductive paste in which the shrinkage behavior during firing is controlled. Furthermore, the object of this disclosure is to provide a method for manufacturing a multilayer electronic component using this photosensitive conductive paste and a multilayer electronic component. [Means for solving the problem]

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

[0009] According to the above embodiment, since the shrinkage behavior of the photosensitive conductive paste during firing is controlled, when it is used as an internal electrode in a multilayer electronic component, the discrepancy with the shrinkage behavior of the base material during firing is reduced, and delamination is suppressed. In addition, since the co-material is not an essential component and it is not necessary to increase the particle size of the conductive powder, the resolution during photolithography 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 of this disclosure, the shrinkage behavior of the photosensitive conductive paste during firing is controlled. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic perspective view showing a multilayer electronic component. [Figure 2] This is a schematic exploded perspective view showing a multilayer electronic component. [Modes 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 embodiments of this disclosure, will be described in detail with reference to the illustrated embodiments. Note that some of the drawings are schematic and may not reflect actual dimensions or proportions.

[0013] (Overall configuration of a multilayer electronic component) 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 components are depicted transparently to facilitate understanding of their structure, but they may also be semi-transparent or opaque. In Figure 1, the coil is omitted to facilitate understanding of the structure. In Figure 2, the external electrodes are omitted for clarity.

[0014] Hereinafter, a multilayer coil component will be described as an example of the multilayer electronic component. 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 first and second external electrodes 6a and 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 connected 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 sometimes be referred to as the upper side.

[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 a layered structure that spreads 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 considering the range of realistic 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 the main components. 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.

[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 lamination 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 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 connected to the second external electrode 6b.

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

[0021] Coil 5 comprises a plurality of coil wirings 2 stacked along the axial direction, and via wirings (not shown) extending along the axial direction and connecting adjacent coil wirings 2 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 electrically connected in series to form a helix.

[0022] The coil wiring 2 is formed by winding it on 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 via wiring is provided in the via holes 3 of the insulating layer 40 and penetrates the insulating layer 40 in the thickness direction (Z direction). Adjacent coil wirings 2 in the stacking direction are electrically connected in series via the via wiring.

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

[0024] (Detailed composition of photosensitive conductive paste) Next, the detailed configuration of the photosensitive conductive paste used to form the coil 5 will be described. The following description focuses on the photosensitive conductive paste used to form the coil 5 of a multilayer electronic component 10, which is a multilayer coil component. However, the photosensitive conductive paste of this disclosure is not limited to this and can be used to form 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 this disclosure can be used to form capacitor electrodes.

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

[0026] <Conductive powder> The conductive powder is sintered by firing to become the conductor of the coil 5. The type of 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 conductive powder in the photosensitive conductive paste may be 65% by weight or more and 90% by weight or less. From the viewpoint of suppressing shrinkage of the photosensitive conductive paste after firing, the content of conductive powder in the photosensitive conductive paste may be 70% by weight or more and 85% by weight or less.

[0027] The average particle size D50 (median diameter) of the conductive powder may be between 0.5 μm and 5.0 μm, from the viewpoint of forming a fine coil pattern 5. The average particle size D50 is the 50% particle size in the volume-based particle size distribution, measured by a laser diffraction particle size distribution analyzer (e.g., Microtrac-Bell MT3000).

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

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

[0030] Organic components decompose upon heating. This weight loss (in this case, synonymous with volume loss) of organic components causes the coil 5 to shrink. However, if the shrinkage behavior of the photosensitive conductive paste and the shrinkage behavior of the base material correspond during firing, it is possible to suppress delamination, a structural defect that can occur between the resulting coil 5 and the base material 4.

[0031] The base material typically contains borosilicate glass, whose softening point is usually above 700°C. When the glass component softens due to heating above 700°C, the sintering of the base material proceeds rapidly, resulting in a tightly sintered structure. In other words, the base material exhibits a shrinkage behavior in which it shrinks little before the glass component softens, and then shrinks rapidly after the glass component softens.

[0032] The cured organic component used in the photosensitive conductive paste relating to this disclosure (hereinafter sometimes simply referred to as "cured product") satisfies the following conditions A and B in an oxygen atmosphere. (Condition A) In thermogravimetric measurements, the weight loss rate at 300°C is less than 50%. (Condition B) In thermogravimetric measurements, 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. As mentioned above, the shrinkage of the base material is also small up to 300°C. In other words, up to 300°C, both the shrinkage of the photosensitive conductive paste and the base material are small, and their shrinkage behaviors correspond. The weight loss rate of the cured product at 300°C (hereinafter sometimes referred to as ΔTG) may be less than 40%, less than 35%, or 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 begins to soften. If the above organic components remain when the glass component of the base material begins to soften, the molten glass component will trap the decomposed and gasified organic components. The gaseous organic components remaining inside the multilayer electronic component 10 will remain in the base material as voids, contributing to structural defects.

[0035] Condition B indicates that the decomposition of the cured material 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. Above 700°C, as described above, the glass components contained in the base material begin to soften. By completing the decomposition of the cured material by 700°C, the trapping of gaseous organic components as described above is suppressed. The weight loss rate of the cured material at 600°C may be 100%.

[0036] By satisfying both conditions A and B above, the organic components contained in the photosensitive conductive paste will decompose slowly up to 300°C, and complete decomposition (weight reduction rate becomes 100%) between 300°C and 700°C. In other words, the shrinkage behavior of the base material during firing corresponds to the shrinkage behavior of the photosensitive conductive paste, so delamination can be expected to be suppressed.

[0037] The cured product described above is obtained by mixing each organic component in the proportions used in a photosensitive conductive paste and curing it. Alternatively, the cured product may be obtained by curing a mixture obtained by mixing a photosensitive monomer, an alkali-soluble polymer, and a photopolymerization initiator in the proportions used in a photosensitive conductive paste. This is because the amount of other organic components (typically additives described later) is small, and therefore has little effect on ΔTG.

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

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

[0040] Condition C indicates that the weight of the cured product decreases at a constant, gradual rate even after exceeding 300°C. This means that the shrinkage of the photosensitive conductive paste proceeds slowly until degreasing is complete. This shrinkage behavior more closely corresponds to the shrinkage behavior of the base material during firing, and therefore further suppression of delamination can be expected.

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

[0042] Alkali-soluble polymers Alkali-soluble polymers are neutralized and solubilized by basic compounds. These polymers are removed, for example, during developing with an alkaline developer, along with uncured photosensitive monomers and conductive powders. On the other hand, when photosensitive monomers polymerize due to active energy rays, nearby alkali-soluble polymers form a film together with the polymerized photosensitive monomers, forming, for example, part of the internal electrode pattern. This can improve the adhesion of the internal electrode pattern to the insulating layer.

[0043] The alkali-soluble polymer content may be 30% by weight or more, or 35% by weight or more, relative to the organic component. The alkali-soluble polymer content 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 type of alkali-soluble polymer, or it may contain two or more types of alkali-soluble polymers.

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

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

[0047] Examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, vinylacetic acid, and their dimers and anhydrides. These can be used individually 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, t-butyl acrylate, 2-ethylhexyl acrylate, lauryl acrylate, and isoboronyl acrylate; methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, and isoboronyl methacrylate; fumarate esters such as monoethyl fumarate; and styrene. These can be used individually or in combination of two or more.

[0049] The carboxyl groups of the alkali-soluble polymer may be introduced after the main chain has been formed. For example, the carboxyl groups of the alkali-soluble polymer may be introduced by reacting a compound having epoxy groups in the side chains with an unsaturated monocarboxylic acid, and then further reacting it with a saturated or unsaturated polycarboxylic acid anhydride.

[0050] Alkali-soluble polymers may have unsaturated bonds. Unsaturated bonds in alkali-soluble polymers may be introduced, for example, by adding a monomer that is reactive with the carboxyl group in the side chain and has a polymerizable functional group (typically an epoxy group).

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

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

[0053] Typical examples of easily detachable polymerization units include units derived from ethylene monomer (chemical formula (1) below), propylene monomer (chemical formula (2) below), isobutylene monomer (chemical formula (3) below), styrene monomer (chemical formula (4) below), methyl methacrylate monomer (chemical formula (5) below), tetrafluoroethylene monomer (chemical formula (6) below), and α-methylstyrene monomer (chemical formula (7) below). These are included in the copolymer either individually or in combination of two or more.

[0054] [ka]

[0055] [ka]

[0056] [ka]

[0057] [ka]

[0058] [ka]

[0059] [ka]

[0060] [ka]

[0061] The ratio (N1 / N) of the number of easily detachable polymerization units N1 to the total number of polymerization units N constituting the copolymer may be between 0.2 and 0.6. This makes it easier to obtain a photosensitive conductive paste that satisfies the above conditions A and B. Hereinafter, alkali-soluble polymers with the above ratio (N1 / N) of 0.2 and 0.6 may be referred to as "specific alkali-soluble polymers." The ratio (N1 / N) may be 0.4 or less.

[0062] The ratio (N1 / N) can be calculated by dividing the number of moles of monomers that form easily detachable polymerization units (hereinafter referred to as easily detachable monomers) charged by the total number of moles of multiple raw material monomers used in the production of a specific alkali-soluble polymer.

[0063] Easily detachable monomers are monomers that, when polymerized, form easily detachable polymerization units (for example, units represented by the chemical formulas (1) to (7) above). Examples of easily detachable monomers 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 between 5,000 and 50,000. The acid value of the alkali-soluble polymer may be between 30 mg KOH / g and 150 mg KOH / g.

[0065] <<Photosensitive monomers>> Photosensitive monomers react with photopolymerization initiators to generate monomer radicals. These monomer radicals polymerize to produce polymers.

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

[0067] Photosensitive monomers are not limited in that they have at least one radical reactive group. Examples of radical reactive groups include at least one selected from the group consisting of acrylamide, acryloyl, methacryloyl, allyl, vinyl, styryl, and mercapto groups. Photosensitive monomers may have at least one (meth)acryloyl group as a radical reactive group. "(meth)acryloyl group" represents an acryloyl group and / or a methacryloyl group.

[0068] Photosensitive 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, and ethoxylated nonylphenol (meth)acrylate; tripropylene glycol di(meth)acrylate, isocyanuric acid EO modified di Difunctional (meth)acrylate monomers such as acrylates, 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; glycerin tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, ethoxylated trimethylol 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 Trifunctional (meth)acrylate monomers such as tripropylene glycol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, and 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, and ethoxylated pentaerythritol tetra(meth)acrylate;Examples include 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 heptafunctional (meth)acrylate monomers with seven or more functions, such as tripentaerythritol hepta(meth)acrylate and tripentaerythritol octa(meth)acrylate. These can be used individually or in combination of two or more.

[0069] The photosensitive monomer may be a trifunctional or more (meth)acrylate monomer, a tetrafunctional or more (meth)acrylate monomer, or a pentafunctional or more (meth)acrylate monomer. The photosensitive monomer may be dipentaerythritol monohydroxypenta(meth)acrylate.

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

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

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

[0073] <<Photopolymerization Initiator>> Photopolymerization initiators generate highly reactive radicals through active energy rays. These radicals add to photosensitive monomers, triggering the initiation reaction of the photosensitive monomers. Radicals are generated in a chain reaction, eventually forming polymers derived from the photosensitive monomers. The content of the photopolymerization initiator may be 3% by weight or more, or 5% by weight or more, relative to the organic component. The content of the photopolymerization initiator may be 10% by weight or less, or 8% by weight or less, relative to the organic component.

[0074] Examples of photopolymerization initiators 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 sensitizers, defoamers, anti-settling agents, and dispersants.

[0076] <Solvent> The solvent is not particularly limited and includes, for example, 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 can be used individually or in combination of two or more.

[0077] The solvent content in the photosensitive conductive paste may be 3% by weight or more, or 5% by weight or more. The solvent content 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 is a metal resinate containing a metal having a melting point higher than the melting point of the conductive powder. Examples of metals that can be included in the metal resinate include Rh, Ni, Cu, Mn, and Zr. Examples of such metal resinates include metal octylates, naphthenates, 2-ethylhexanoates, sulfonates, metal mercaptides, and alkoxy metal compounds.

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

[0080] (Manufacturing method for multilayer electronic components) Next, the manufacturing method of the multilayer electronic component 10 will be described. The manufacturing method of the multilayer electronic component 10 consists of the steps of laminating a photosensitive conductive paste onto the insulating layer 40, The process includes a step of sintering a photosensitive conductive paste and an insulating layer 40 at a firing temperature of 800°C or higher, A coil 5 (internal electrode) is formed from a photosensitive conductive paste. The base body 4 is formed from the insulating layer 40. A coil 5 is placed inside the base body 4.

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

[0082] The following describes in detail an example of a method for manufacturing a stacked electronic component 10 using the photosensitive conductive paste of this disclosure.

[0083] As shown in Figure 2, a glass paste, used 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 obtain an insulating layer (glass layer) 40 of a predetermined thickness (for example, about 100 μm). Note that the support film is omitted in Figure 2.

[0084] Insulating pastes such as glass paste contain insulating inorganic components and organic components. Glass paste contains, for example, glass powder and ceramic aggregate (inorganic filler) as insulating inorganic components, and, for example, acrylic polymer as an organic component. Other organic components may include solvents, dispersants, defoamers, etc.

[0085] The type of glass powder contained in the insulating paste is not particularly limited, but for example, an SiO2-B2O3-K2O system glass containing SiO2, B2O3, and K2O in predetermined proportions 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 between 0.1 μm and 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 aggregate may be mixed and used. The average particle size of the ceramic aggregate is not particularly limited, but it may be between 0.1 μm and 5.0 μm.

[0087] The insulating layer 40 may also be made by laminating pre-formed green sheets.

[0088] The photosensitive conductive paste of this disclosure is screen printed onto the insulating layer 40 to a thickness of approximately 5 μm to 20 μm, dried, and then selectively exposed and developed to form the first layer of coil wiring 2.

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

[0090] The photosensitive conductive paste of this disclosure is screen printed over the entire surface again to a film thickness of approximately 5 μm to 10 μm, dried, and then selectively exposed and developed to form the second layer of coil wiring 2.

[0091] The layering 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 printed and dried over the entire surface, and the insulating layer 40 is formed on the uppermost coil wiring 2 by repeating this process the required number of times. This results in a laminated structure formed by interlayer connections of the coil wiring 2 via via holes 3.

[0093] The resulting laminated structure is divided into chip shapes using a dicer, and then the support film, such as PET film, is separated. After that, it is fired at a temperature of 800°C or higher. This firing process sinters the photosensitive conductive paste, forming the coil 5. The insulating layer 40 is also sintered, forming the base body 4.

[0094] A first external electrode 6a and a second external electrode 6b are formed on the laminate after firing. Furthermore, a single-layer or multi-layer plating layer may be applied to the outer surfaces of the first external electrode 6a and the second external electrode 6b by electrolytic plating, electroless plating, or the like.

[0095] As a result, the stacked electronic component 10 shown in Figure 1 is obtained.

[0096] This disclosure is not limited to the embodiments described above, and design modifications are possible without departing from the gist of this disclosure. [Examples]

[0097] The present disclosure will be explained in more detail below with reference to examples, but the present disclosure is by no means limited by the examples below, and it is certainly possible to implement it with appropriate modifications to the extent that it is applicable to the spirit of the preceding and following, and all such modifications are included within the technical scope of the present disclosure.

[0098] [Examples 1-6] (1) Preparation of photosensitive resin Photosensitive resins A to F containing organic components and solvents were obtained by blending each raw material in the proportions shown in Table 1 and thoroughly mixing them. Dipentaerythritol hexa(meth)acrylate was used alone as the photosensitive monomer. As the alkali-soluble polymer, an acrylic polymer (specific alkali-soluble polymer) having carboxyl groups in its side chains and containing easily detachable polymerization units was used.

[0099] [Table 1]

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

[0101] [Table 2]

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

[0103] [Table 3]

[0104] (2) Preparation of photosensitive conductive paste A photosensitive conductive paste for forming internal electrodes was obtained by blending 80% by weight of conductive powder (Ag powder), 18% by weight of each photosensitive resin (A to F), and 2% by weight of a dispersant, and thoroughly mixing this mixture with a three-roll mixer. The photosensitive conductive pastes of Examples 1 to 6 were prepared using each of the photosensitive resins A to F.

[0105] [evaluation] (1) Weight reduction rate Each component other than the solvent and defoamer was mixed in the same proportions as the photosensitive resins A to F shown in Tables 1 and 3 to obtain organic components. These organic components were irradiated with ultraviolet light to obtain cured products. Using a thermogravimetric analyzer, the ΔTG of each cured product at 300°C and 400°C in an oxygen atmosphere, and the temperature T at which 100% weight loss occurred were determined. Δ100 and were measured.

[0106] (2) Preparation and measurement of resistivity evaluation samples The photosensitive conductive pastes prepared in Examples 1-6 were screen printed onto an alumina substrate to a thickness of 10 μm to 20 μm and dried. The pastes were then exposed to light through a photomask with a wiring pattern and developed with an alkaline aqueous solution to form the wiring pattern. The formed wiring pattern was fired at 900°C for 60 minutes to create electrode wiring for resistance measurement. The resistance, line width, line length, and film thickness of the obtained wiring samples were measured. The resistivity was calculated from the calculated wiring volume based on the Ag volume. Resistivity values ​​of 2.2 μΩ·cm or less were classified as A (pass, good), and those exceeding 2.2 μΩ·cm were classified as B (fail).

[0107] (3) Preparation and measurement of firing shrinkage rate samples The photosensitive conductive paste prepared using the method described above was printed onto a smooth substrate, dried, and then exposed to light through a photomask with a wiring pattern. The wiring pattern was then formed by developing it with an alkaline aqueous solution. The volume of the wiring pattern in the resulting paste was calculated using a laser displacement meter. Next, these dot patterns were heat-treated at 700°C. The volume of the wiring pattern in the heat-treated samples was again calculated using a laser displacement meter. Based on the volume values ​​before and after heat treatment, the percentage decrease in volume due to heat treatment was calculated, and this value was defined as the firing shrinkage rate.

[0108] In the 700°C heat treatment, photosensitive resins A to F are 100% decomposed. Typically, substrate materials that do not contain organic components exhibit little shrinkage. Therefore, the small shrinkage rate of the photosensitive conductive paste (i.e., internal electrodes) after the 700°C heat treatment also indicates that delamination is suppressed.

[0109] A shrinkage rate of less than 30% at 700℃ was rated A (pass, better than average), a level of 30% to less than 40% was rated B (pass, good), and a level of 40% or more was rated C (fail).

[0110] (4) Patterning ability (resolution) After screen printing a photosensitive conductive paste onto an alumina substrate, it was dried at 60°C for 30 minutes to form a photosensitive conductive paste film with a thickness of 10 μm. Next, a beam of light from an ultra-high pressure mercury lamp (manufactured by Ushio Inc.) was applied to the substrate through a photomask with a linear pattern of L / S = 25 / 25 μm to a surface of 1000 mJ / cm². 2 A photosensitive conductive paste film was subjected to mask exposure by irradiation under the condition of (405 nm). Subsequently, it was developed with an aqueous triethanolamine solution. Processes that were formed without residue or skipped lines were classified as A (pass), and those with skipped lines were classified as B (fail).

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

[0112] [Table 4]

[0113] The photosensitive conductive paste used in the example satisfies conditions A and B above, exhibiting a small firing shrinkage rate at a firing temperature of 700°C, thus suppressing delamination. Furthermore, the photosensitive conductive paste used in the example satisfies condition C above, and the shrinkage of the photosensitive conductive paste progresses slowly until degreasing is complete, further suppressing delamination.

[0114] In addition, the photosensitive conductive paste used in the examples does not contain any co-materials, resulting in low resistivity after firing and good patternability. Therefore, it can be seen that the electrical resistance is low and the resolution during photolithographic patterning is improved. In other words, the photosensitive conductive paste used in the examples can be used to obtain internal electrodes that suppress delamination, have low electrical resistance, and have excellent resolution during photolithographic patterning.

[0115] In contrast, for photosensitive conductive pastes that do not meet condition A above and have a weight loss rate of 50% or more at 300°C, the shrinkage rate of the photosensitive conductive paste up to 300°C is expected to be excessively large and will not correspond to the shrinkage behavior of the base material, so suppression of delamination cannot be expected. For photosensitive conductive pastes that do not meet condition B above and have a weight loss rate of less than 100% at 700°C, residual organic components are expected to be trapped within the base material 4, so suppression of delamination cannot be expected either.

[0116] <1> It contains conductive powder, organic components, and a solvent. The organic component comprises an alkali-soluble polymer, a photosensitive monomer, and a photopolymerization initiator, wherein the thermal decomposition of the cured product of the organic component in an oxygen atmosphere satisfies the following conditions A and B, resulting in a photosensitive conductive paste. (Condition A) In thermogravimetric measurements, the weight loss rate at 300°C is less than 50%. (Condition B) In thermogravimetric measurements, the weight loss rate at 700°C is 100%. <2> Under condition A, the weight loss rate at 300°C is less than 30%. <1> The photosensitive conductive paste described in [reference]. <3> Under condition B, the weight loss rate at 600°C is 100%. <1> or <2> The photosensitive conductive paste described in [the document]. <4> The thermal decomposition of the aforementioned cured product in an oxygen atmosphere satisfies the following condition C: <1> from <3> A photosensitive conductive paste as described in any of the following. (Condition C) In thermogravimetric measurements, the change in weight loss rate in the temperature range of 300°C to 400°C is 70% or less. <5> The alkali-soluble polymer comprises a copolymer containing easily detachable polymerization units that exhibit main-chain cleavage during thermal decomposition. The ratio of the number of easily detachable polymerization units to the total number of polymerization units constituting the copolymer is 0.2 or more and 0.6 or less. <1> from <4> A photosensitive conductive paste as described in any of the following. <6> The ratio of the weight Wm of the photosensitive monomer to the weight Wp of the alkali-soluble polymer (Wm / Wp) is 0.2 or more and 0.9 or less. <5> The photosensitive conductive paste described in [the document]. <7> The conductive powder is silver powder. <1> from <6> A photosensitive conductive paste as described in any of the following. <8> The average particle size D50 of the silver powder is between 0.5 μm and 5.0 μm. <7> The photosensitive conductive paste described in [the document]. <9> <1> from <8> A step of laminating a photosensitive conductive paste described in any of the above onto an insulating layer, The process includes sintering the photosensitive conductive paste and the insulating layer at a firing temperature of 800°C or higher. An internal electrode is formed from the aforementioned photosensitive conductive paste. A base body is formed from the aforementioned insulating layer. A method for manufacturing a stacked electronic component, comprising providing the internal electrodes within the aforementioned substrate. <10> A substrate containing borosilicate glass and inorganic filler, Provided within the aforementioned body, <1> from <8> A multilayer electronic component comprising an internal electrode which is a sintered body of a photosensitive conductive paste as described in any of the above. [Explanation of symbols]

[0117] 2. Coil Wiring 3 Beer Hall 4. Base body 5 coils 5a 1st end 5b 2nd end 6a 1st external electrode 6b 2nd external electrode 10. Stacked Electronic Components 40 Insulating layer 41, 42 1st end face, 2nd end face 43, 44 1st side, 2nd side 45 Bottom 46 Top surface

Claims

1. It contains conductive powder, organic components, and a solvent. The organic component comprises 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 a photosensitive conductive paste. (Condition A) In thermogravimetric measurements, the weight loss rate at 300°C is less than 50%. (Condition B) In thermogravimetric measurements, 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 under condition A is less than 30%.

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

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

5. The alkali-soluble polymer comprises a copolymer containing easily detachable polymerization units that exhibit main-chain cleavage during thermal decomposition. The photosensitive conductive paste according to claim 1 or 2, wherein the ratio of the number of 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 of the weight Wm of the photosensitive monomer to the weight Wp of the alkali-soluble polymer (Wm / Wp) 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 μm or less.

9. A step of laminating the photosensitive conductive paste according to claim 1 or 2 onto an insulating layer, The process includes sintering the photosensitive conductive paste and the insulating layer at a firing temperature of 800°C or higher. An internal electrode is formed from the aforementioned photosensitive conductive paste. A base body is formed from the aforementioned insulating layer. A method for manufacturing a stacked electronic component, comprising providing the internal electrodes within the aforementioned substrate.

10. A substrate containing borosilicate glass and inorganic filler, A stacked electronic component comprising an internal electrode provided within the substrate, which is a sintered body of a photosensitive conductive paste according to claim 1 or 2.

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