JP7446355B2 - Photosensitive composition and its use - Google Patents

Description

The present invention relates to a photosensitive composition and its use. Specifically, the present invention relates to a photosensitive composition containing a cellulose compound and a (meth)acrylic resin as an organic binder, and the use of the photosensitive composition.

Conventionally, a method has been known in which a conductive layer is formed on a substrate by a photolithography method using a photosensitive composition containing a conductive powder, a photosensitive component, and a photopolymerization initiator (for example, Patent Documents 1 to 3). (See 3). In this method, for example, first, a photosensitive composition is applied onto a base material and dried to form a conductive film (conductive film forming step). Next, a photomask having a predetermined opening pattern is placed on the formed conductive film, and the conductive film is exposed to light through the photomask (exposure step). As a result, the exposed portion of the conductive film is photocured. Next, the unexposed portions that were shielded from light by the photomask are corroded and removed using an alkaline aqueous developer (developing step). Then, the conductive film formed into the desired pattern is baked onto the base material (firing step). According to the photolithography method including the steps described above, it is possible to form a finer conductive layer than various conventional printing methods.

Japanese Patent Application Publication No. 2011-007864 International Publication No. 2015-152208 Japanese Patent Application Publication No. 2017-182901

Incidentally, in recent years, various electronic devices have rapidly become smaller and have higher performance, and electronic components (for example, inductor components, etc.) mounted in electronic devices are also required to be further smaller and more dense. Along with this, in manufacturing electronic components, there is a demand for lower resistance and thinner wires (narrowing) of conductive layers. Specifically, by increasing the thickness of the conductive layer and improving the resolution of the pattern, the line width of the wiring and the space between adjacent wirings (line and space: L/S) are 20 μm/20 μm or less. It is required to form fine lines.

However, it is difficult to stably form a thick conductive layer or a conductive layer with a small L/S while achieving both developability and resolution. For example, when the conductive film becomes thicker, it becomes difficult for light to reach deep parts close to the base material. Therefore, photocuring becomes insufficient, and peeling and disconnection are likely to occur in exposed areas during the development process. Furthermore, if L/S is small, it becomes difficult to supply the aqueous developer to the spaces between the wirings during the development process. As a result, unexposed portions are difficult to remove, and adjacent wirings may be connected to each other, resulting in short-circuit defects. In addition, if the developing process time is set to be long in order to suppress the occurrence of such short-circuit defects, the exposed area may become thinner, which may cause the developed pattern itself to peel off or a part of the pattern to peel off, resulting in wire breakage. Ta.
The above problems are considered to be caused by a short development margin. Here, the "development margin" refers to the point at which the unexposed area is completely removed (break point (B.P.)) during the development process, and defects such as peeling and disconnection in the exposed area that makes up the development pattern. It represents the length of time until it occurs. That is, if a sufficient development margin is not ensured, the exposed area will thin or disappear immediately after the unexposed area is removed. For this reason, especially when forming fine lines, it is difficult to determine the timing to end the development process because the development margin is short, and as a result, the development process management during manufacturing may be burdened. In terms of process control, there was a need for a technology that could secure a long development margin and form fine lines with good reproducibility.

The present invention was created in view of these points, and its purpose is to provide a technology that improves the developability and resolution of a photosensitive composition and further lengthens the development margin. It is to be.

The present inventors focused on using a cellulose-based compound as an organic binder contained in a photosensitive composition and using an organic binder having a glass transition point different from that of the cellulose-based compound. Furthermore, by using a cellulose compound and a (meth)acrylic resin whose glass transition point is lower than a predetermined temperature, the developability and resolution of the photosensitive composition are improved, and the development margin is lengthened. This discovery led to the completion of the present invention.

According to the technology disclosed herein, a photosensitive composition containing a conductive powder (a), an organic binder (b), a photopolymerizable monomer (c), and a photoinitiator (d) is provided. be done.
The organic binder (b) contains a cellulose compound (b1) and a (meth)acrylic resin (b2) having a glass transition point of less than 80°C. When the total amount of the organic binder (b) is 100% by mass, the content of the cellulose compound (b1) is 40% by mass or more; and the (meth)acrylic resin (b2) is 60% by mass or less ; is.
The photosensitive composition having such a structure contains, as an organic binder (b), a predetermined amount of a cellulose compound (b1) and a (meth)acrylic resin (b2) having a glass transition point of less than 80°C. This makes it easier to remove unexposed portions in the development step, thereby shortening development time and improving developability. In addition, the high glass transition point of the cellulose compound can be buffered, and the conductive powder and the organic component contained in the photosensitive composition become more compatible. Therefore, in the development step, the conductive powder in the unexposed areas is thoroughly washed away, and the generation of residue can be reduced. Furthermore, the above configuration is effective in increasing the development margin of the photosensitive composition.
By using a photosensitive composition having such a structure, it is possible to form a fine conductive layer with stable line width and cross-sectional shape, and it is possible to improve the electrical characteristics of electronic components (for example, the high frequency characteristics of inductor components). can.

Preferably, the content of the cellulose compound (b1) is 50% by mass or more; and the content of the (meth)acrylic resin (b2) is less than 50% by mass.
According to this configuration, in addition to the above effects, the peel strength of the conductive film can be improved.
More preferably, the content of the cellulose compound (b1) is 60% by mass or more and 80% by mass or less; and the content of the (meth)acrylic resin (b2) is 20% by mass or more and 40% by mass or less.
According to this configuration, in addition to the above-mentioned effects, the peel strength of the conductive film can be improved, and fine lines can be more suitably realized.

In a preferred embodiment, the organic binder (b) further includes a (meth)acrylic resin (b3) different from the (meth)acrylic resin (b2). The difference between the glass transition point of the (meth)acrylic resin (b2) and the glass transition point of the (meth)acrylic resin (b3) is 15° C. or more.
In addition to the above effects, such a configuration can improve the peel strength of the conductive film. It is more suitable for improving the resolution of the photosensitive composition and increasing the development margin.
In a more preferred embodiment, the (meth)acrylic resin (b3) has a glass transition point of 80°C or higher.
According to this configuration, the above-mentioned effects are more suitably exhibited, and fine lines can be realized.
Preferably, when the total amount of the organic binder (b) is 100% by mass, the content of the (meth)acrylic resin (b3) is 15% by mass or more.
According to this configuration, the above-mentioned effects can be more suitably exhibited, and fine lines can be realized more suitably. With the above configuration, formation of a fine line with L/S of 12 μm/12 μm can be realized.

In one preferred embodiment, the conductive powder (a) contains silver-based particles.
According to this configuration, it is possible to realize a conductive layer with an excellent balance between cost and low resistance.

Further, according to the technology disclosed herein, there is provided a composite comprising a green sheet and a conductive film disposed on the green sheet and made of a dried product of the photosensitive composition.
In a green sheet having such a configuration, the effects of the technology disclosed herein can be suitably exhibited.

Further, the present invention provides an electronic component including a conductive layer made of a fired product of the photosensitive composition. According to the photosensitive composition, a fine-line conductive layer with a small L/S and/or a thick conductive layer can be stably formed. Therefore, by using the above-mentioned photosensitive composition, it is possible to suitably realize an electronic component having a small size and/or a high-density conductive layer and having excellent electrical properties. Further, it is possible to suitably realize an electronic component in which insulation defects are less likely to occur.

Further, according to the present invention, the photosensitive composition is applied onto a substrate, exposed to light, developed, and then baked to form a conductive layer consisting of a fired product of the photosensitive composition. A method of manufacturing a component is provided. According to such a manufacturing method, it is possible to stably manufacture an electronic component having a small size and/or a high-density conductive layer and having excellent electrical properties, and it is possible to improve productivity and yield.

FIG. 1 is a schematic cross-sectional view of a multilayer chip inductor according to an embodiment. This is a laser microscope observation image (500x) of a wiring pattern with L/S of 20 μm/20 μm in the resolution evaluation test of Example 1. This is a laser microscope observation image (500x) of a wiring pattern with L/S of 15 μm/15 μm in the resolution evaluation test of Example 1. This is a laser microscope observation image (500x) of a wiring pattern with L/S of 12 μm/12 μm in the resolution evaluation test of Example 1. This is an example of a laser microscope observation image (500x) of a wiring pattern that was evaluated as "Δ" in the resolution evaluation test. This is an example of a laser microscope observation image (500x) of a wiring pattern that was evaluated as "x" in the resolution evaluation test. This is an example of a laser microscope observation image (500x) of a wiring pattern that was evaluated as "x" in the resolution evaluation test. This is an example of a laser microscope observation image (500x) of a wiring pattern that was evaluated as "x" in the resolution evaluation test.

Hereinafter, preferred embodiments of the present invention will be described. It should be noted that matters other than matters specifically mentioned in this specification (for example, the composition of the photosensitive composition) that are necessary for carrying out the present invention (for example, the method for preparing the photosensitive composition, the conductive film, the conductive film, etc.) (layer formation method, electronic component manufacturing method, etc.) can be understood based on the technical content taught in this specification and the general technical common sense of those skilled in the art. The present invention can be implemented based on the content disclosed in this specification and the common general knowledge in the field.
Note that in this specification and claims, when a predetermined numerical range is expressed as A to B (A and B are arbitrary numerical values), it means greater than or equal to A and less than or equal to B. Therefore, cases in which the value exceeds A and are lower than B are included.

In this specification, the term "conductive film" refers to a film-like material (dried material) obtained by drying a photosensitive composition at a temperature below the boiling point of the organic component (approximately 200° C. or below, for example 100° C. or below). The conductive film includes all unfired (before firing) film-like bodies. Furthermore, in this specification, the term "conductive layer" refers to a sintered body (fired product) obtained by firing a photosensitive composition at a temperature equal to or higher than the sintering temperature of the conductive powder. The conductive layer includes wiring (linear bodies), wiring patterns, and solid patterns.

Furthermore, in this specification, the term "glass transition point" refers to a glass transition temperature (Tg) based on differential scanning calorimetry (DSC). In addition, the term "weight average molecular weight" as used herein refers to the weight-based average molecular weight measured by gel permeation chromatography (GPC) and converted using a standard polystyrene calibration curve. Moreover, in this specification, "acid value" is the content (mg) of potassium hydroxide (KOH) required to neutralize free fatty acids contained in a unit sample (1 g). The unit is mgKOH/g.

≪Photosensitive composition≫
The photosensitive composition disclosed herein includes a conductive powder (a), an organic binder (b), a photopolymerizable monomer (c), and a photopolymerization initiator (d).
The conductive powder (a) is an inorganic component, and the organic binder (b), the photopolymerizable monomer (c), and the photopolymerization initiator (d) are organic components. The photosensitive composition disclosed herein can be used, for example, to produce a conductive layer including fine-line wiring with an L/S of 20 μm/20 μm or less, and furthermore, a conductive layer including ultra-fine line wiring with L/S of 15 μm/15 μm or less. It can be used suitably. Further, it can be suitably used for producing a thick conductive layer having a thickness of 5 μm or more, and even 10 μm or more. Each component will be explained in order below.

<Conductive powder (a)>
The conductive powder is a component that imparts electrical conductivity to the conductive layer. The type of conductive powder is not particularly limited, and one type of conductive powder can be used alone or two or more types can be used in an appropriate combination, depending on the purpose, for example, from among conventionally known types. Examples of the conductive powder include gold (Au), silver (Ag), copper (Cu), platinum (Pt), palladium (Pd), aluminum (Al), nickel (Ni), ruthenium (Ru), and rhodium ( Examples include simple metals such as Rh), tungsten (W), iridium (Ir), and osmium (Os), as well as mixtures and alloys thereof. Examples of the alloy include silver alloys such as silver-palladium (Ag-Pd), silver-platinum (Ag-Pt), and silver-copper (Ag-Cu).

In one preferred embodiment, the conductive powder includes silver-based particles. Silver is relatively inexpensive and has high electrical conductivity. Therefore, when the conductive powder contains silver-based particles, it is possible to realize a conductive layer with an excellent balance between cost and low resistance.
Note that in this specification, the term "silver-based particles" includes all particles containing a silver component. Examples of silver-based particles include simple silver, the above-mentioned silver alloys, core-shell particles having a silver-based particle as a core, and silver-ceramic core-shell particles. The metal-ceramic core-shell particle has a core portion that includes a metal material and a coating portion that includes a ceramic material and covers at least a portion of the surface of the core portion. In applications where a conductive layer is formed on a ceramic base material to manufacture ceramic electronic components, it is possible to improve the integrity with the ceramic base material, and to suitably suppress peeling and disconnection of the conductive layer after firing. can.

Although not particularly limited, examples of ceramic materials constituting the coating portion of the core-shell particles include zirconium oxide (zirconia), magnesium oxide (magnesia), aluminum oxide (alumina), silicon oxide (silica), and titanium oxide. (titania), cerium oxide (ceria), yttrium oxide (yttria), barium titanate, and other oxide materials; cordierite, mullite, forsterite, steatite, sialon, zircon, ferrite, and other composite oxide materials Nitride-based materials such as silicon nitride and aluminum nitride; Carbide-based materials such as silicon carbide; Hydroxide-based materials such as hydroxyapatite; and the like.

An organic surface treatment agent may be attached to the surface of the conductive powder. The organic surface treatment agent can, for example, improve the dispersibility of the conductive powder in the photosensitive composition, increase the affinity between the conductive powder and other ingredients, and oxidize the surface of the metal constituting the conductive powder. It can be used for at least one of the following purposes: Examples of the organic surface treatment agent include carboxylic acids such as fatty acids, benzotriazole compounds, and the like.

Although not particularly limited, the _D50 particle size of the conductive powder (the particle size corresponding to 50% of the integrated value from the smallest particle size in the volume-based particle size distribution based on laser diffraction/scattering method; the same applies hereinafter) ) may be approximately 0.1 to 10 μm. By setting the _D50 particle size within the above range, exposure performance can be improved and fine lines can be formed more stably. From the viewpoint of suppressing aggregation of the conductive powder and improving storage stability in the photosensitive composition, the _D50 particle size of the conductive powder may be, for example, 0.5 μm or more, 1 μm or more. . In addition, from the viewpoint of improving fine wire forming properties, making the conductive layer denser, and lowering the resistance, the _D50 particle size of the conductive powder is, for example, 5 μm or less, 4.5 μm or less, 4 μm or less, Furthermore, it may be 3 μm or less.

Although not particularly limited, the conductive powder may be spherical or approximately spherical. Thereby, exposure performance can be improved and fine lines can be formed more stably. Furthermore, spherical or approximately spherical conductive powder rolls more easily on the surface or inside of the conductive film than scale-like conductive powder. Therefore, application of the technology disclosed herein is effective. Note that in this specification, "spherical" means that the average aspect ratio is 1.0. Moreover, in this specification, "substantially spherical" means that the average aspect ratio is more than 1.0 and less than 2.0, preferably less than 1.5. In this specification, "spherical" and "substantially spherical" refer to a shape that can be generally regarded as a sphere (ball) as a whole, and include an elliptical shape, a polygonal shape, a disk-spherical shape, and the like. Furthermore, in this specification, the term "average aspect ratio" refers to the arithmetic mean value of the aspect ratio (major axis/ (breadth-to-breadth ratio).

Although not particularly limited, the proportion of the conductive powder (a) in the entire photosensitive composition is approximately 50% by mass or more, typically 60 to 95% by mass, for example 70 to 90% by mass. It's okay. By satisfying the above range, a conductive layer with high density and electrical conductivity can be formed. Moreover, the handleability of the photosensitive composition and the workability when molding a conductive film can be improved.

Although not particularly limited, the conductive powder may have a lightness L ^* of 50 or more in the L ^* a ^* b ^* color system based on JIS Z 8781:2013. This allows light to stably reach deep parts of the uncured conductive film during exposure, and can stably penetrate thick conductive layers with a thickness of 5 μm or more, or even 10 μm or more. can be formed into From the above viewpoint, the lightness L ^* of the conductive powder may be approximately 55 or more, for example, 60 or more. The lightness L ^* can be adjusted, for example, by the type of conductive powder described above and the _D50 particle size. Note that the lightness L ^* can be measured using, for example, a spectrophotometer based on JIS Z 8722:2009.

<Organic binder (b)>
The organic binder is a component that enhances the adhesiveness between the base material and the conductive film (uncured material). The organic binder, unlike the photopolymerizable monomer (c) described below, does not have photosensitivity (referring to the property of causing chemical or structural changes due to light; for example, photocurability).
The photosensitive composition disclosed herein contains a cellulose compound (b1) and a (meth)acrylic resin as an organic binder (b). In addition, in this specification, "(meth)acrylate" is a term that includes "methacrylate" and "acrylate."

As the cellulose compound (b1), one type from conventionally known compounds can be used alone, or two or more types can be used in an appropriate combination. In this specification, the term "cellulose compound" includes cellulose, cellulose derivatives, and salts thereof. Cellulose-based compounds typically have a plurality of hydroxyl groups in the glucose ring, which is a repeating structural unit of cellulose, and exhibit good water solubility, so they can be easily removed with an aqueous developer in the development process. Examples of cellulose-based compounds include, for example, hydroxyalkylcelluloses such as hydroxymethylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, and hydroxypropylmethylcellulose; alkylcelluloses such as methylcellulose and ethylcellulose; carboxyalkylcelluloses such as carboxymethylcellulose; and the like.
As the cellulose compound (b1), commercially available compounds can be used without particular restriction. As a commercially available cellulose compound, for example, one manufactured by Shin-Etsu Polymer Co., Ltd. can be used.

When an alkaline aqueous developer is used in the development process, the cellulose compound contains highly alkali-soluble structural moieties, such as phenolic hydroxyl groups, carboxyl groups, ester bonding groups, sulfo groups, phosphono groups, and boronic acid groups. It may have an acidic group. For example, it may have a carboxyl group. It is more preferable that the cellulose compound contains an acidic group in the repeating structural unit. The acidic group is a substituent that has a dissociable proton and exhibits acidity in water. A part of the acidic group may be esterified. The acidic group may be bonded to the carbon of the main chain (the carbon chain with the maximum number of carbon atoms; the same applies hereinafter) of the cellulose compound, or the side chain (the carbon chain branching from the main chain; the same applies hereinafter). ) may be bonded to carbon. The inclusion of highly alkali-soluble structural parts makes it easier to remove unexposed parts with an alkaline aqueous developer more quickly and without residue.

<(meth)acrylic resin>
As the (meth)acrylic resin, one type of conventionally known non-photosensitive (meth)acrylic resins can be used alone, or two or more types can be used in an appropriate combination. Examples of such (meth)acrylic resins include homopolymers of alkyl (meth)acrylates, copolymers containing alkyl (meth)acrylate as a main monomer and a submonomer having copolymerizability with the main monomer, and modified products thereof. The (meth)acrylic resin may have a highly alkali-soluble structural moiety, for example, an acidic group such as a phenolic hydroxyl group, a carboxyl group, an ester bonding group, a sulfo group, a phosphono group, or a boronic acid group. For example, it may have a carboxyl group. The inclusion of highly alkali-soluble structural parts makes it easier to remove unexposed parts with an alkaline aqueous developer more quickly and without residue. Furthermore, by including the (meth)acrylic resin, the flexibility of the conductive layer and the followability to the base material can be improved, and the occurrence of peeling and disconnection can be better suppressed. Furthermore, the durability of the conductive layer can be improved.

ここで、上記式において、
Ｒ_１は、水素（Ｈ）原子またはメチル基（－ＣＨ_３）であり、
Ｒ_２は、水素（Ｈ）原子またはメチル基（－ＣＨ_３）であり、
Ｘは、水素（Ｈ）原子、または以下に示される有機官能基であり、
Ｙは、水素（Ｈ）原子、または以下に示される有機官能基であり、
ａおよびｂは、独立して０以上の整数である。 Specific examples of the (meth)acrylic resin include acrylic resins having the following structure.

Here, in the above formula,
R ₁ is a hydrogen (H) atom or a methyl group (-CH ₃ ),
R ₂ is a hydrogen (H) atom or a methyl group (-CH ₃ ),
X is a hydrogen (H) atom or an organic functional group shown below,
Y is a hydrogen (H) atom or an organic functional group shown below,
a and b are independently integers of 0 or more.

および、

に示されるような環状アルキル基；フェニルメチル（－ＣＨ_２－Ｐｈ）、フェノキシエチル（－ＣＨ_２ＣＨ_２－Ｏ－Ｐｈ）等の芳香環含有基；等が挙げられる。
Ｒ_１，Ｒ_２，ＸおよびＹを適宜設定することによって、例えば、所望のガラス転移点を有する（メタ）アクリル系樹脂を得ることができる。 The above organic functional groups include methyl (-CH ₃ ), ethyl (-CH ₂ CH ₃ ), n-butyl (-CH ₂ CH ₂ CH ₂ CH ₃ ), iso-butyl (-CH ₂ CH (CH ₃ ) ₂ ), and alkyl groups such as tert-butyl (-C(CH ₃ ) ₃ ), hydroxyethyl group, 2-hydroxypropyl group; cyclohexyl,

and,

Examples include cyclic alkyl groups as shown in the following; aromatic ring-containing groups such as phenylmethyl (-CH ₂ -Ph) and phenoxyethyl (-CH ₂ CH ₂ -O-Ph); and the like.
By appropriately setting R ₁ , R ₂ , X and Y, for example, a (meth)acrylic resin having a desired glass transition point can be obtained.

The photosensitive composition disclosed herein includes a (meth)acrylic resin (b2) having a glass transition point of less than 80° C. as the (meth)acrylic resin. Thereby, the resolution of the photosensitive composition can be improved and the development margin can be lengthened. The glass transition point of the (meth)acrylic resin (b2) may be 75°C or lower, 70°C or lower, or 65°C or lower. Further, the glass transition point may be 50°C or higher, or 55°C or higher. The glass transition point is preferably 55°C or higher and 65°C or lower (for example, about 60°C). The (meth)acrylic resin (b2) may be any resin as long as it has a glass transition point as described above, and it can be used alone or in an appropriate combination of two or more.

It is preferable that the photosensitive composition disclosed herein further contains another (meth)acrylic resin (b3) different from the (meth)acrylic resin (b2). The glass transition point of the (meth)acrylic resin (b3) may be higher than the glass transition point of the (meth)acrylic resin (b2). The difference between the glass transition point of the (meth)acrylic resin (b2) and the glass transition point of the (meth)acrylic resin (b3) may be approximately 15°C or higher, 20°C or higher, or 25°C or higher. Further, the difference may be approximately 50°C or less, 45°C or less, or 40°C or less.
Further, the glass transition point of the (meth)acrylic resin (b3) is preferably 80°C or higher, and may be approximately 80 to 120°C, for example 85 to 100°C. The (meth)acrylic resin (b3) may be any resin as long as it has a glass transition point as described above, and one type can be used alone or two or more types can be used in an appropriate combination.
As the (meth)acrylic resin (b2) and the (meth)acrylic resin (b3), commercially available resins can be used without particular limitation. For example, commercially available products manufactured by Mitsubishi Rayon Co., Ltd. and Shin-Nakamura Chemical Co., Ltd. can be used.

The organic binder may be composed only of the above-mentioned cellulose compound and (meth)acrylic resin. In addition to the organic binder described above, other compounds conventionally known to be usable for this type of application may be included, as long as the effects of the technology disclosed herein are not significantly reduced. Examples of such compounds include phenol resins, epoxy resins, polyester resins, polyamide resins, and polycarbonate resins that do not have photosensitivity.

In the organic binder (b), the cellulose compound (b1) is the first component (the component with the highest content on a mass basis). The proportion of the cellulose compound (b1) in the entire organic binder (b) is 40% by mass or more (for example, more than 40% by mass), preferably 50% by mass or more (for example, more than 50% by mass) on a mass basis. In other words, when the total amount of the organic binder (b) is 100% by mass, the content of the cellulose compound (b1) is 40% by mass or more, preferably 50% by mass or more. The content ratio may be, for example, 45 to 90% by mass, 55 to 85% by mass, or 60 to 80% by mass.
By setting the content of the cellulose compound in the organic binder (b) to the predetermined content ratio, the development time can be shortened.

The proportion of compounds other than cellulose compounds in the entire organic binder (b) is less than 50% by mass on a mass basis.
In one preferred embodiment, for example, when the total amount of the organic binder (b) is 100% by mass, the content rate of the (meth)acrylic resin (b2) is 60% by mass or less (for example, less than 60% by mass), Preferably, it can be 50% by mass or less (for example, less than 50% by mass). The content ratio may be, for example, 10 to 55% by weight, 15 to 45% by weight, or 20 to 40% by weight. By including the (meth)acrylic resin (b2) in a predetermined content ratio as the organic binder (b), appropriate viscosity can be imparted to the photosensitive composition, and the occurrence of peeling and wire breakage can be suppressed. . Further, resolution can be improved and the development margin can be lengthened. When the (meth)acrylic resin (b3) is included as the organic binder (b), its content may be 15% by mass or less, about 2 to 12% by mass. By including the (meth)acrylic resin (b3) as the organic binder (b), the effects of the present invention can be better realized.

Although not particularly limited, the weight average molecular weight of the organic binder may be approximately 5,000 or more, for example, 10,000 or more. This increases the adhesion (tackiness) of the conductive film to the substrate before photocuring, and can suitably suppress the occurrence of peeling, disconnection, etc. in the development process. The weight average molecular weight of the organic binder may be approximately 1 million or less, typically 500,000 or less, for example 300,000 or less, 200,000 or less, or 100,000 or less. The weight average molecular weight of the cellulose compound (b1) may be larger than that of compounds other than cellulose compounds. For example, it may be twice or more larger than compounds other than cellulose compounds. Specifically, the weight average molecular weight of the cellulose compound (b1) may be approximately 10,000 to 500,000, for example, 50,000 to 200,000. Further, the weight average molecular weight of the compound other than the cellulose compound may be approximately 5,000 to 100,000, for example, 10,000 to 50,000.

Although not particularly limited, the organic binder may have an acid value. The overall acid value of the organic binder may be approximately 10 mgKOH/g or more, for example, 20 mgKOH/g or more, or even 30 mgKOH/g or more. This increases the solubility in an aqueous developer in the development step, and can better improve the removability of unexposed areas. The overall acid value of the organic binder may be approximately 300 mgKOH/g or less, for example 200 mgKOH/g or less, or even 150 mgKOH/g or less. As a result, the solubility in an aqueous developer can be appropriately suppressed in the development process, and peeling and disconnection of exposed areas can be better suppressed. The acid value of the cellulose compound (b1) may be lower than that of compounds other than cellulose compounds. For example, it may be 1/2 times or less or 1/3 times or less of compounds other than cellulose compounds. Specifically, the acid value of the cellulose compound (b1) may be approximately 10 to 300 mgKOH/g, for example 20 to 200 mgKOH/g.

Although not particularly limited, the proportion of the organic binder (b) in the entire photosensitive composition is approximately 0.1 to 20% by mass, typically 0.5 to 10% by mass, for example 2 to 8% by mass. It may be mass %. By setting the proportion of the organic binder to a predetermined value or more, it is possible to improve the developability and shorten the development time in the development step. Furthermore, the holding power (etching resistance) of the exposed portion to the base material is increased, and peeling and disconnection of the exposed portion can be better suppressed. Furthermore, by setting the proportion of the organic binder to a predetermined value or less, the proportion of the photosensitive component, that is, the proportion of the photopolymerizable monomer (c) described below, is relatively improved, and the conductive film is stably cured in the exposure process. can be done.

<Photopolymerizable monomer (c)>
The photopolymerizable monomer is a photosensitive component that causes a polymerization reaction with active species generated from the photopolymerization initiator (d) described below to form a crosslinked structure. In this specification, "photopolymerizable monomer" refers to monofunctional monomers having one polymerizable functional group per molecule, polyfunctional monomers having two or more polymerizable functional groups per molecule, and and modified products. Photopolymerizable monomers typically have one or more unsaturated bonds and/or cyclic structures.

As the photopolymerizable monomer, one type from conventionally known ones can be used alone, or two or more types can be used in an appropriate combination. Examples of photopolymerizable monomers include radically polymerizable monomers that have one or more unsaturated bonds such as (meth)acryloyl groups and vinyl groups, and cationically polymerizable monomers that have a cyclic structure such as epoxy groups. It will be done. Specific examples include (meth)acrylate monomers, urethane-modified (meth)acrylate monomers having urethane bonds, epoxy-modified (meth)acrylate monomers, silicone-modified (meth)acrylate monomers, and the like. Among these, the photopolymerizable monomer preferably contains a (meth)acrylate monomer having a (meth)acryloyl group. This increases the affinity with the (meth)acrylic resin and improves the storage stability of the photosensitive composition. In addition, in this specification, "(meth)acryloyl group" refers to "methacryloyl group (-C(=O)-C(CH ₃ )=CH ₂ )" and "acryloyl group (-C(=O)-CH = _CH2 )".

(Meth)acrylate monomers include triethylene glycol monoacrylate, triethylene glycol monomethacrylate, tetraethylene glycol monoacrylate, tetraethylene glycol monomethacrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate, dipentaerythritol pentaacrylate, dipenta Examples include erythritol hexaacrylate, tripentaerythritol heptaacrylate, tripentaerythritol octaacrylate, tetrapentaerythritol nonaacrylate, and tetrapentaerythritol decaacrylate. Among these, monomers having three or more (meth)acryloyl groups, more preferably five or more (meth)acryloyl groups per molecule are preferred from the viewpoint of improving photocurability.

In another preferred embodiment, the photopolymerizable monomer includes a urethane bond-containing monomer having a urethane bond (-NH-C(=O)-O-). By including the urethane bond-containing monomer, it is possible to better improve the etching resistance of the exposed portion and to realize a conductive layer with excellent flexibility and stretchability. Therefore, the adhesion between the base material and the conductive layer can be improved, and the occurrence of peeling and disconnection can be suppressed to a high level. Examples of the urethane bond-containing monomer include urethane-modified (meth)acrylate monomers and urethane-modified epoxy monomers containing urethane bonds.

Although not particularly limited, the weight average molecular weight of the photopolymerizable monomer may be approximately 10,000 or less, for example 5,000 or less, 3,000 or less, or 2,000 or less. The weight average molecular weight of the photopolymerizable monomer may be smaller than the cellulose compound (b1), smaller than the (meth)acrylic resin (b2), and smaller than the (meth)acrylic resin (b3). It can be small.

Although not particularly limited, the proportion of the photopolymerizable monomer (c) in the entire photosensitive composition is approximately 0.1 to 50% by mass, typically 1 to 30% by mass, for example 2 to 10% by mass. It may be mass %. The proportion of the photopolymerizable monomer (c) may be higher than that of the organic binder (b). By setting the proportion of the photopolymerizable monomer to a predetermined value or more, the exposure time can be shortened in the exposure step. By setting the proportion of the photopolymerizable monomer to a predetermined value or less, the proportion of the polymer component, that is, the proportion of the organic binder (b), is relatively improved, and the holding power of the photosensitive composition to the substrate is increased. As a result, peeling and disconnection of the exposed portion can be better suppressed.

<Photopolymerization initiator (d)>
A photopolymerization initiator is a component that is decomposed by irradiation with light energy such as ultraviolet rays, generates active species such as radicals and cations, and initiates a polymerization reaction of a photosensitive component. As the photopolymerization initiator, one kind can be used alone or two or more kinds can be used in an appropriate combination from among conventionally known ones, depending on the type of photosensitive component, for example. The photopolymerization initiator may be a radical photopolymerization initiator, a cationic photopolymerization initiator, or an anionic photopolymerization initiator. Typical examples include alkylphenone photopolymerization initiators, acetophenone photopolymerization initiators, benzophenone photopolymerization initiators, benzoin photopolymerization initiators, acylphosphine oxide photopolymerization initiators, and the like.

Examples of photopolymerization initiators include 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholino phenyl)-butan-1-one (2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone-1), 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2 , 4,6-trimethylbenzoyl-diphenyl-phosphine oxide, 2,4-diethylthioxanthone, benzophenone and the like.

Although not particularly limited, the proportion of the photopolymerization initiator (d) in the entire photosensitive composition is approximately 0.01 to 5% by mass, typically 0.1 to 4% by mass, for example 0. It may be .2 to 3% by mass. This allows the conductive layer to be formed more stably.

<Organic dispersion medium (e)>
In addition to the above-mentioned essential components (a) to (d), the photosensitive composition may contain an organic dispersion medium for dispersing or dissolving these components. The organic dispersion medium is a component that imparts appropriate viscosity and fluidity to the photosensitive composition and improves the handling of the photosensitive composition and the workability when forming a conductive film. be. As the organic dispersion medium, one type can be used alone or two or more types can be used in an appropriate combination from among those conventionally known, depending on the type of the photopolymerizable monomer (c), for example.

Examples of organic dispersion media include alcohol solvents such as terpineol; glycol solvents such as ethylene glycol, propylene glycol, and diethylene glycol; ether solvents such as dipropylene glycol methyl ether and methyl cellosolve (ethylene glycol monomethyl ether); diethylene glycol Ester solvents such as monobutyl ether acetate, butyl carbitol acetate (diethylene glycol monobutyl ether acetate), and isobornyl acetate; Hydrocarbon solvents such as toluene, xylene, naphtha, and petroleum hydrocarbons; Organic solvents such as mineral spirits; can be mentioned.

Although not particularly limited, when the photosensitive composition contains an organic dispersion medium (e), the proportion of the organic dispersion medium (e) in the entire photosensitive composition is approximately 1 to 50% by mass, Typically it may be 3-30% by weight, for example 4-20% by weight.

<Other additive ingredients>
In addition to the above-described components, the photosensitive composition may further contain various additional components as necessary, as long as the effects of the technology disclosed herein are not significantly impaired. As the additive component, one type from conventionally known ones can be used alone, or two or more types can be used in an appropriate combination. Examples of additive components include photosensitizers, polymerization inhibitors, radical scavengers, antioxidants, ultraviolet absorbers, plasticizers, surfactants, leveling agents, thickeners, wetting agents, dispersants, Examples include antifoaming agents, antistatic agents, antigelation agents, stabilizers, preservatives, pigments, fillers (organic or inorganic fillers), and the like.

Although not particularly limited, when the photosensitive composition contains an additive component, the proportion of the additive component in the entire photosensitive composition is approximately 5% by mass or less, typically 3% by mass or less, for example 2% by mass or less. It may be less than 1% by weight, preferably less than 1% by weight.

In the photosensitive composition disclosed herein, a predetermined content of a cellulose compound (b1) and a (meth)acrylic resin (b2) having a glass transition point of less than 80° C. are used as an organic binder (b). ,include. That is, when the total amount of the organic binder (b) is 100% by mass, the content of the cellulose compound (b1) is 40% by mass or more, and the content of the (meth)acrylic resin (b2) is 60% by mass. % or less. This makes it easier to remove unexposed portions in the development step, thereby shortening development time and improving developability. In addition, the high glass transition point of the cellulose compound can be buffered, and the conductive powder and the organic component contained in the photosensitive composition become more compatible. Therefore, in the development step, the conductive powder in the unexposed areas is thoroughly washed away, and the generation of residue can be reduced. Furthermore, such a configuration is effective in increasing the development margin of the photosensitive composition. As a result, a fine conductive layer with stable line width and cross-sectional shape can be formed, and the electrical characteristics of electronic components (for example, high frequency characteristics of inductor components) can be improved.

≪Applications of photosensitive composition≫
According to the photosensitive composition disclosed herein, a fine-line conductive layer or a thick conductive layer can be stably formed. Therefore, the photosensitive composition disclosed herein can be suitably used, for example, for forming conductive layers in various electronic components such as inductor components, capacitor components, and multilayer circuit boards. The electronic component may be of various mounting forms, such as a surface mount type or a through-hole mount type. The electronic component may be of a laminated type, a wire-wound type, or a thin film type. Typical examples of inductor components include, for example, high frequency filters, common mode filters, inductors (coils) for high frequency circuits, inductors (coils) for general circuits, high frequency filters, choke coils, transformers, and the like.

An example of an electronic component is a ceramic electronic component. In this specification, "ceramic electronic components" refers to all electronic components made of ceramic materials, including amorphous ceramic substrates (glass ceramic substrates) and crystalline (i.e., non-glass) ceramics. Includes all electronic components that have a base material. Typical examples of ceramic electronic components include high-frequency filters with ceramic substrates, ceramic inductors (coils), ceramic capacitors, low temperature co-fired ceramic substrates (LTCC substrates), and high-temperature co-fired multilayer ceramic substrates. (High Temperature Co-fired Ceramics Substrate: HTCC base material), etc.

FIG. 1 is a cross-sectional view schematically showing the structure of a multilayer chip inductor 1. As shown in FIG. Note that the dimensional relationships (length, width, thickness, etc.) in FIG. 1 do not necessarily reflect the actual dimensional relationships. Further, the symbols X and Y in the drawings represent the left-right direction and the up-down direction, respectively. However, this is only for convenience of explanation.

The multilayer chip inductor 1 includes a main body 10 and external electrodes 20 provided on both side surfaces of the main body 10 in the left-right direction X. The laminated chip inductor 1 has a size of, for example, a 1608 shape (1.6 mm x 0.8 mm) or a 2520 shape (2.5 mm x 2.0 mm). The main body portion 10 has a structural portion in which a ceramic layer (dielectric layer) 12 and an internal electrode layer 14 are integrated. The ceramic layer 12 is made of, for example, the ceramic material described above as being capable of forming a coating of conductive powder. In the vertical direction Y, internal electrode layers 14 are arranged between the ceramic layers 12 . The internal electrode layer 14 is formed using the above-mentioned photosensitive composition. Internal electrode layers 14 that are adjacent to each other in the vertical direction Y with the ceramic layer 12 in between are electrically connected through vias 16 provided in the ceramic layer 12 . As a result, the internal electrode layer 14 is configured in a three-dimensional spiral shape (spiral shape). Both ends of the internal electrode layer 14 are connected to the external electrodes 20, respectively.

The multilayer chip inductor 1 can be manufactured, for example, by the following procedure. That is, first, a paste containing a ceramic material as a raw material, a binder resin, and an organic solvent is prepared, and the paste is supplied onto a carrier sheet to form a ceramic green sheet. Next, this ceramic green sheet is rolled and then cut into a desired size to obtain a plurality of green sheets for forming ceramic layers. Next, via holes are appropriately formed at predetermined positions of the plurality of green sheets for forming ceramic layers using a punching machine or the like. Next, using the photosensitive composition described above, a conductive film having a predetermined coil pattern is formed at predetermined positions on the plurality of green sheets for forming ceramic layers. As an example, the following steps: (Step S1: Conductive film forming step) A photosensitive composition is applied onto a ceramic layer forming green sheet and dried to form a conductive film made of a dried photosensitive composition. Molding process; (Step S2: Exposure process) A process of covering the conductive film with a photomask having a predetermined opening pattern and exposing the conductive film to light through the photomask to partially photocure the conductive film; (Step S3: Developing process) ) A step of etching the photocured conductive film to remove an unexposed portion; A conductive film in an unfired state can be formed on a green sheet. Note that a green sheet with a conductive film, which has a conductive film on the green sheet, is an example of a composite.

In addition, in molding a conductive film using the said photosensitive composition, a conventionally well-known method can be used suitably. For example, in (Step S1), the photosensitive composition can be applied using various printing methods such as screen printing, a bar coater, or the like. The photosensitive composition is preferably dried at a temperature below the boiling points of the photopolymerizable monomer and photopolymerization initiator, typically from 50 to 100°C. In (step S2), an exposure machine that emits radiation such as visible light, ultraviolet rays, X-rays, electron beams, α-rays, β-rays, and γ-rays can be used for exposure. As an example, an exposure machine that emits light in the wavelength range of 10 to 500 nm, such as an ultraviolet irradiation lamp such as a high-pressure mercury lamp, a metal halide lamp, or a xenon lamp, can be used. In (step S3), an alkaline aqueous developer can typically be used for etching. For example, an aqueous solution containing sodium hydroxide, sodium carbonate, etc. can be used. The concentration of the alkaline aqueous solution may be adjusted to, for example, 0.01 to 0.5% by mass.

Next, (Step S4: Firing Step) A plurality of ceramic layer forming green sheets on which unfired conductive films are formed are stacked and pressure bonded. In this way, a laminate of unfired ceramic green sheets is produced. Next, the ceramic green sheet laminate is fired at, for example, 600 to 1000°C. As a result, the ceramic green sheets are integrally sintered to form the main body portion 10 including the ceramic layer 12 and the internal electrode layer 14 made of the fired body of the photosensitive composition. Then, a suitable external electrode forming paste is applied to both ends of the main body part 10 and fired, thereby forming the external electrodes 20. In the manner described above, the multilayer chip inductor 1 can be manufactured.

Hereinafter, some examples related to the present invention will be described, but the present invention is not intended to be limited to those shown in the examples.

Example 1
(1) Preparation of photosensitive composition First, silver powder ( _D50 particle size: 2 μm) was prepared as the conductive powder (a). Further, as an organic binder (b), a cellulose compound shown in Table 1, (meth)acrylic resin 2, and (meth)acrylic resin 4 were prepared. Moreover, a urethane acrylate monomer was prepared as a photopolymerizable monomer (c). In addition, as a photopolymerization initiator (d), 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone-1 and 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide were mixed in 1: A mixture of Step 3 was prepared.

A photosensitive composition according to Example 1 was prepared by dissolving components (a) to (d) prepared as above in an organic dispersion medium (e). At this time, assuming that the entire photosensitive composition is 100% by mass, the component (a) is 75% by mass, the component (b) is 5% by mass, the component (c) is 6% by mass, and the component (d) is was 1% by mass, and component (e) was 13% by mass.
Regarding the component (b), the respective content ratios (mass %) were as shown in Table 2 when the entire component (b) was taken as 100 mass %.

(2) Preparation of wiring pattern First, the photosensitive composition prepared above was screen printed on a commercially available ceramic green sheet in a size of 4 cm square. Next, this was dried at 60° C. for 15 minutes, and a conductive film (solid film) with a film thickness of 8 μm was formed on the green sheet (conductive film forming step). Next, a photomask having three types of opening patterns, L/S=20 μm/20 μm, 15/15 μm, and 12/12 μm, was placed over the conductive film. Then, with a photomask placed over the conductive film, light was irradiated by an exposure machine at an exposure illuminance of 50 mW/cm ² and an exposure amount of 900 mJ/cm ² to cure the exposed portion (exposure step). After exposure, a 0.1% by mass Na ₂ CO ₃ aqueous solution (aqueous developer) at 27° C. was sprayed onto the surface of the ceramic green sheet until a break point (B.P.) was reached (development step). After removing the unexposed areas in this way, they were washed with pure water and dried at room temperature. In this way, a conductive film (dry film) having three types of L/S wiring patterns was formed on the ceramic green sheet.
In the above development process, the unexposed areas on the ceramic green sheet are developed with a 0.1% by mass aqueous developer, and the time required to visually confirm that the unexposed areas are gone is determined by B. P. It was measured as the time t until reaching .

(3) Evaluation of resolution In the above conductive film molding process, a conductive film (solid film) with a thickness of 8 μm was molded. In addition, in the development step, the development time was set to be 1.2 times the time t (ie, 1.2t) in consideration of the development margin. Other than that, a conductive film was formed in the same manner as in the formation of the above wiring pattern. That is, here, three types of L/S were used to form a total of three patterns of conductive films.
Next, each of the wiring patterns produced above was observed with a laser microscope (magnification: 500 times) in 10 fields each to check for chipping, peeling, and residue between the wirings. Furthermore, the average value per visual field was calculated.
Note that FIGS. 2A to 2C show laser microscope observation images (500x magnification) of the wiring pattern of Example 1. 2A shows a wiring pattern with L/S of 20 μm/20 μm, FIG. 2B shows a wiring pattern with L/S of 15 μm/15 μm, and FIG. 2C shows a wiring pattern with L/S of 12 μm/12 μm.

Based on the above results, resolution was evaluated using the following index. The results are shown in the "Resolution" column of Table 2.
“〇”: Neither peeling nor chipping of the wiring, nor any residue between the lines was observed.
"Δ": Wiring chipping and/or inter-line residue was observed at two or less locations per field of view.
"x": Wiring chipping and/or inter-line residue was observed at three or more locations per visual field. Or peeling of wiring was observed.
Note that examples of laser microscope observation images (500x magnification) of wiring patterns that were evaluated as "△" or "x" in the resolution evaluation test are shown in FIGS. 3A to 3D for reference. FIG. 3A shows a wiring pattern evaluated as "Δ". FIGS. 3B to 3D are wiring patterns evaluated as "x".

(4) Evaluation of development margin In the conductive film forming process described above, a conductive film (solid film) with a thickness of 8 μm was formed. Further, in the above-mentioned development step, development was carried out with the developing time being 1.3 times the above-mentioned time t (i.e., 1.3t). Other than that, a conductive film was formed in the same manner as the above wiring pattern formation. That is, here, three types of L/S were used to form a total of three patterns of conductive films. Next, each of the wiring patterns produced above was observed with a laser microscope (magnification: 500 times) in 10 fields at a time to confirm the presence or absence of chipping, peeling, and residue between the wirings. Furthermore, the average value per field of view was calculated, and the resolution at (A) development time of 1.3 t was evaluated using the indicators of "〇", "△", and "x" as described above.

Furthermore, a conductive film was formed as described above, except that the development time was set to 1.3 times the above time t (i.e., 1.3t), and laser microscope observation was performed. The resolution at (B) development time of 1.4 t was evaluated using the "×" index.

Based on the evaluation results of (A) resolution at a development time of 1.3t and (B) resolution at a development time of 1.4t, the development margin was evaluated using the following index. The results are shown in the "Development Margin" column of Table 2.
“〇”: Both (A) and (B) are “〇”.
"△": (A) is "〇" and (B) is △. Alternatively, both (A) and (B) are "Δ".
"x": At least one of (A) and (B) is "x".

(5) Comprehensive evaluation Based on the above evaluation results of (3) resolution and (4) development margin, comprehensive evaluation was performed using the indicators shown in Table 3. In addition, if the resolution evaluation is "△" or "x" for either L/S = 20/20 μm or L/S = 15/15 μm, the development margin will not be evaluated and the overall The evaluation was set as "x". That is, in the column "Evaluation of development margin" in Table 3, "-" indicates that no evaluation was performed.
The results are shown in the "Comprehensive Evaluation" column of Table 2.

Examples 2 to 7
A photosensitive composition was prepared in the same manner as in Example 1, except that the cellulose compounds and (meth)acrylic resins shown in Table 1 were used as the organic binder (b) at the content rates shown in the relevant columns of Table 2. Then, the evaluations (2) to (5) above were performed. The evaluation results of Examples 2 to 7 are all shown in Table 2.

Comparative examples 1 to 11
A photosensitive composition was prepared in the same manner as in Example 1, except that the cellulose compounds and (meth)acrylic resins shown in Table 1 were used as the organic binder (b) at the content rates shown in the relevant columns of Table 2. Then, the evaluations (2) to (5) above were performed. The evaluation results of Comparative Examples 1 to 11 are all shown in Table 2.
In Examples 1 to 7 and Comparative Examples 1 to 11, three types of silver powders having the same _D50 particle size of 2 μm but different types were used as the conductive powder (a).

Regarding comparative examples, Comparative Examples 1 to 4 and 8 to 11 are test examples that do not contain a (meth)acrylic resin having a glass transition point of less than 80° C. as the organic binder (b). In these comparative examples, the development time t (27 seconds to 47 seconds) was longer than in the examples. Regarding the evaluation of the development margin, the photosensitive compositions of Comparative Examples 1 to 4 and 8 to 10 had L/S of 15 μm/15 μm or less, and the photosensitive composition of Comparative Example 11 had L/S of 20 μm/20 μm or less. Chips and peeling occurred. From this, it was found that the photosensitive compositions of these comparative examples did not have a sufficiently long development margin when forming fine lines.

Comparative Examples 5 to 7 are test examples in which a (meth)acrylic resin having a glass transition point of less than 80° C. is included as the organic binder (b), but the content ratio thereof is higher than the content ratio of the cellulose compound. Looking at the resolution of these comparative examples, there is a tendency that the lower the content of the cellulose compound, the lower the resolution. Regarding the development margin, in Comparative Examples 5 to 7, chipping and peeling occurred when the L/S was 15 μm/15 μm or less. From this, it was found that the photosensitive compositions of these comparative examples did not have a sufficiently long development margin when forming fine lines.

As shown in Table 2, for Comparative Examples 1 to 11, all of Examples 1 to 7 had an overall evaluation of "〇" or higher. The development time t was stable at 20 seconds to 25 seconds. Regarding the resolution, no peeling was observed even when the L/S was 12 μm/12 μm. Furthermore, regarding the development margin, neither chipping nor peeling was observed when L/S was 15 μm/15 μm. From this, in a photosensitive composition containing a conductive powder (a), an organic binder (b), a photopolymerizable monomer (c), and a photopolymerization initiator (d), the organic binder (b) contains a cellulose-based compound and a (meth)acrylic resin (b1) having a glass transition point of less than 80°C, and the content of the cellulose-based compound is 40% by mass when the total amount of the organic binder (b) is 100% by mass. It was confirmed that a photosensitive composition in which the content of the (meth)acrylic resin (b1) is 60% by mass or less is excellent in resolution and development margin. This indicates that the photosensitive composition disclosed herein is suitable for forming stable fine lines.

Comparing Examples 1 to 5 with Examples 6 and 7, no peeling occurred when L/S of Examples 1 to 5 was 12 μm/12 μm. From this, by setting the content of the cellulose compound (b1) to 50% by mass or more and the content of the (meth)acrylic resin (b2) to less than 50% by mass, the peel strength improves and is suitable. It was confirmed that high resolution and development margins were achieved.

Furthermore, when comparing Examples 1 and 2 with Examples 3 to 5, it is found that Examples 1 and 2 containing a (meth)acrylic resin with a glass transition temperature of 90°C were evaluated for resolution and development margin. were all ``〇'', and the overall evaluation was ``◎'' in both cases. This is because, in both evaluations of resolution and development margin, no chipping or peeling occurred at L/S of 12 μm/12 μm, and a suitable fine line was formed. As a result, the photosensitive composition may further include (meth)acrylic resin (b2) having a glass transition point of 80° C. or higher as the organic binder (b) in order to further suitably achieve fine line formation. This was confirmed to be favorable.
The above results demonstrate the significance of the technology disclosed herein.

Although the present invention has been described in detail above, these are merely examples, and the present invention can be modified in various ways without departing from the spirit thereof.

1 Multilayer chip inductor 10 Main body 12 Ceramic layer 14 Internal electrode layer 16 Via 20 External electrode

Claims (7)

A method for manufacturing an electronic component including a conductive layer, the method comprising:
Preparing a ceramic green sheet and a photosensitive composition, applying the photosensitive composition onto the ceramic green sheet and drying it to form a conductive film made of a dried product of the photosensitive composition. Process;
an exposure step of partially photocuring the conductive film by covering the conductive film with a photomask having an opening pattern and exposing the conductive film to light through the photomask;
a developing step of etching the photocured conductive film to remove an unexposed portion of the conductive film; and
a firing step of firing the ceramic green sheet on which the conductive film is formed in an unfired state after the developing step;
encompasses,
here,
In the forming step, the photosensitive composition includes:
Containing a conductive powder (a), an organic binder (b), a photopolymerizable monomer (c), and a photopolymerization initiator (d),
The organic binder (b) is
A cellulose compound (b1),
(meth)acrylic resin (b2) having a glass transition point of 55° C. or higher and 65° C. or lower and a weight average molecular weight of 10,000 to 50,000;
When the total amount of the organic binder (b) is 100% by mass,
The content of the cellulose compound (b1) is 40% by mass or more,
The content ratio of the (meth)acrylic resin (b2) is 20% by mass or more and 60% by mass or less,
The (meth)acrylic resin (b2) has the following structure:

(Here, R ₁ is a hydrogen (H) atom or a methyl group,
R ₂ is a hydrogen (H) atom or a methyl group,
X is a hydrogen (H) atom, methyl group, ethyl group, n-butyl group, iso-butyl group, or tert-butyl group,
Y is a hydrogen (H) atom, methyl group, ethyl group, n-butyl group, iso-butyl group, or tert-butyl group,
a and b are independently integers of 0 or more. )
A photosensitive composition is provided, comprising:
In the exposure step,
By using a photomask as the photomask that can form a wiring pattern in which the line width of a plurality of wirings and the space between adjacent wirings are both 20 μm or less,
In the firing step,
A manufacturing method, wherein a conductive layer including a plurality of wirings each having a line width of 20 μm or less and a space between adjacent wirings is provided on the fired body of the ceramic green sheet. In the formation step, as the organic binder (b), when the total amount is 100% by mass,
The content of the cellulose compound (b1) is 50% by mass or more, and
The content ratio of the (meth)acrylic resin (b2) is less than 50% by mass,
The manufacturing method according to claim 1, comprising preparing the photosensitive composition containing an organic binder. In the forming step, when the total amount is 100% by mass as the organic binder (b),
The content of the cellulose compound (b1) is 60% by mass or more and 80% by mass or less, and
The content ratio of the (meth)acrylic resin (b2) is 20% by mass or more and 40% by mass or less,
The manufacturing method according to claim 1 or 2, comprising preparing the photosensitive composition containing an organic binder. In the forming step, as the organic binder (b),
Furthermore, it contains another (meth)acrylic resin (b3) different from the (meth)acrylic resin (b2),
The difference between the glass transition point of the (meth)acrylic resin (b2) and the glass transition point of the (meth)acrylic resin (b3) is 15°C or more;
The manufacturing method according to any one of claims 1 to 3, comprising preparing the photosensitive composition containing an organic binder. The manufacturing method according to claim 4, wherein the (meth)acrylic resin (b3) has a glass transition point of 80°C or higher. In the formation step, as the organic binder (b), when the total amount is 100% by mass,
The content ratio of the (meth)acrylic resin (b3) is 15% by mass or less,
The manufacturing method according to claim 4 or 5, wherein the photosensitive composition containing an organic binder is prepared. The manufacturing method according to any one of claims 1 to 6, wherein in the forming step, the photosensitive composition containing a conductive powder containing silver-based particles is prepared as the conductive powder (a).

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