JP6694099B1 - Method for producing photosensitive composition, photosensitive composition in paste form, method for producing electronic component and electronic component, device for determining blending ratio of organic components in photosensitive composition, computer program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photosensitive composition capable of forming fine wiring with a desired line width with good reproducibility. According to the present invention, there is provided a method for producing a photosensitive composition containing a conductive powder in a predetermined blending ratio. In this manufacturing method, the particle size of the conductive powder used is measured to obtain an actual measurement value (step S1); the first actual measurement value is prepared in advance according to the type of the conductive powder used. A step of confirming an expected deviation value with respect to a predetermined target level in comparison with a correlation equation (step S2); based on a second correlation equation prepared in advance according to the type of the conductive powder to be used, The step of determining the compounding ratio of the organic components so as to cancel the expected deviation value (step S3); [Selection diagram] Figure 2

Description

  The present invention relates to a method for producing a photosensitive composition, a paste-like photosensitive composition, a method for producing an electronic component and an electronic component, an apparatus for determining a mixing ratio of organic components in the photosensitive composition, and a computer program.

  In the manufacture of electronic components such as inductors, a method of forming a conductive layer on a substrate by photolithography using a photosensitive composition containing a conductive powder, a photopolymerizable resin, and a photopolymerization initiator is known. (See, for example, Patent Documents 1 and 2). In such a method, first, a photosensitive composition is applied onto a substrate and dried to form a conductive film (conductive film forming step). Next, the formed conductive film is covered with a photomask having a predetermined opening pattern, and the conductive film is exposed through the photomask (exposure step). As a result, the exposed portion of the conductive film is photo-cured. Next, the unexposed portion shielded from light by the photomask is corroded and removed by a developing solution (developing step). Then, the conductive film having a desired pattern is baked to be baked on the base material (baking step). According to the photolithography method including the steps as described above, a fine conductive layer can be formed as compared with the conventional various printing methods.

Patent No. 5163687 International publication 2015/122345

  By the way, in recent years, miniaturization and high performance of various electronic devices are rapidly progressing, and further miniaturization and high density of electronic components mounted on the electronic devices are required. Along with this, in the production of electronic components such as a multilayer chip inductor, it is required to reduce the resistance of the conductive layer and thin the wire (narrow). More specifically, the line width of the wirings forming the conductive layer and the space between adjacent wirings (line and space: L / S) are miniaturized to 30 μm / 30 μm or less, further 20 μm / 20 μm or less. Is required. If the L / S of the conductive layer is small, the line width of the wiring will be slightly thicker, and adjacent wires will be connected to each other to cause a short circuit defect. Conversely, if the line width of the wiring is slightly thin, peeling will occur. It is easy to cause wire breakage. For this reason, in an electronic component such as a multilayer chip inductor, a large variation in line width may adversely affect the product characteristics or reduce the yield. Therefore, from the viewpoint of mass production, by suppressing the variation in the line width of the conductive film after development to be low, the variation in the line width of the conductive layer after firing can be suppressed, and fine-line wiring in electronic components can be formed with good reproducibility. Will be required.

  The present invention has been made in view of the above points, and an object thereof is to provide a photosensitive composition capable of forming fine line-shaped wiring with a desired line width with good reproducibility. Another related object is to provide a method of manufacturing an electronic component and the electronic component. Another related object is to provide an apparatus and a computer program for determining a blending ratio of organic components in a photosensitive composition.

  The inventors of the present invention have conducted extensive studies on each component of the photosensitive composition, and have found that the particle size of the conductive powder is newly an important factor for determining the line width after development. did. That is, FIG. 1A is a schematic side view showing the state of the exposure step when the conductive powder 1A having a relatively large particle size is used. As shown in FIG. 1A, when the particle size of the conductive powder 1A is large, light entering the inside of the conductive film through the opening of the photomask is reflected on the surface of the conductive powder 1A, and light is easily scattered. Therefore, light easily spreads in the horizontal direction of the conductive film. As a result, the light reaches the periphery of the opening of the photomask (the portion shielded by the photomask), and the line width tends to be thicker than the width of the opening of the photomask. On the other hand, FIG. 1B is a schematic side view showing the state of the exposure step when the conductive powder 1B having a relatively small particle size is used. As shown in FIG. 1B, when the particle size of the conductive powder 1B is small, the light entering the inside of the conductive film through the opening of the photomask is hardly reflected on the surface of the conductive powder 1B and the light is scattered. It can be suppressed. For this reason, light is unlikely to spread in the horizontal direction of the conductive film, and the line width tends to be relatively narrower than that in FIG. From this, in order to stabilize the line width, it can be said that it is desirable to highly control the particle size of the conductive powder used.

  However, according to the investigation by the present inventors, the particle size of the conductive powder varies more or less when the manufacturing lot (product unit) is different. For example, when the inventors purchased conductive powders of several manufacturing lots having an average particle size (nominal value) of 2.9 μm and actually measured the average particle size, the average particle size (actual measurement value) was found to be the nominal value. From ± 0.4 μm. This variation is considered to be caused by variations in the manufacturing process. Therefore, it was expected that the line width would vary due to fluctuations in the average particle size (actually measured value) of the conductive powder. Therefore, the present inventors wondered whether variations in the line width that could occur due to variations between conductive powder production lots could be buffered during the production of the photosensitive composition. As a result of further studies, the present invention was created.

  According to the present invention, there is provided a method for producing a photosensitive composition containing a conductive powder in a predetermined compounding ratio. This manufacturing method is a step of measuring the particle size of the conductive powder to be used to obtain an actual measurement value; comparing the actual measurement value with a first correlation equation prepared in advance according to the type of the conductive powder used. Then, a step of confirming an expected shift value with respect to a predetermined target level; based on a second correlation formula prepared in advance according to the type of the conductive powder to be used, the above organic shift value is canceled so as to cancel Determining the blending ratio of the components;

  In the above-mentioned manufacturing method, the particle size of the conductive powder used for manufacturing the photosensitive composition is measured in advance, and an expected deviation value with respect to the target level is simulated. Then, based on the result of the simulation, the blending ratio of the organic components is determined so as to cancel the predicted deviation value. As a result, the influence of variations in the production lot of the conductive powder is reduced, and it is possible to suppress the variation in the line width caused by the difference in the production lot of the conductive powder. Therefore, it is not necessary to control the particle size of the conductive powder to a high degree, and for example, even if the production lot of the purchased conductive powder is switched in the middle, it is possible to stably form a desired line width. A composition can be provided. As a result, the yield can be improved and mass productivity and productivity can be improved.

  In a preferred embodiment disclosed herein, the organic component is an organic component that adjusts at least one of light absorption and photopolymerizability of the photosensitive composition. The organic component may be at least one of a photopolymerization initiator system, a light absorber, and a polymerization inhibitor. The organic component may be a photopolymerization initiator system. This makes it possible to stabilize the compounding ratio of, for example, a photocurable component (a component that is cured by a polymerization reaction, such as a photocurable compound) in the photosensitive composition, and various characteristics of the conductive film, for example, with respect to the substrate The effect of the technology disclosed herein can be achieved while maintaining high tackiness and the like as a whole.

  The first correlation equation is represented by, for example, a correlation equation between the line width and the actual measurement value of the conductive powder. The second correlation equation is represented by, for example, the correlation equation between the line width and the compounding ratio of the organic component. The second correlation equation may be represented by a linear function. Since the two variables have a proportional relationship in the linear function, the mixture ratio can be calculated simply and easily.

  In a preferred embodiment disclosed herein, the conductive powder contains silver-based particles. This makes it possible to realize a conductive layer having an excellent balance between cost and low resistance.

  In a preferred aspect disclosed herein, the first conductive powder is core-shell particles containing a metal material to be a core and a ceramic material coating at least a part of the surface of the core. This makes it possible to improve the stability of the conductive powder in the photosensitive composition better and to realize a highly durable conductive layer. In addition, for example, in the application of manufacturing a ceramic electronic component by forming a conductive layer on a ceramic base material (ceramic base material), the integrity with the ceramic base material can be improved.

  Further, according to the present invention, a step of applying the photosensitive composition onto a substrate, performing photocuring and etching, and then firing to form a conductive layer formed of a fired body of the photosensitive composition. A method of manufacturing an electronic component is provided that includes: According to such a manufacturing method, it is possible to preferably manufacture an electronic component including a small-sized and / or high-density conductive layer.

  Further, according to the present invention, there is provided a compounding ratio determining device for determining a compounding ratio of an organic component to a photosensitive composition containing a conductive powder at a predetermined compounding ratio. This mixing ratio determination device is prepared in advance according to the type of conductive powder to be used, and an input section for receiving the user's input and inputting the type of conductive powder to be used and the measured value of the particle size. Based on the first correlation equation, a storage unit that stores the first correlation equation and the second correlation equation that have been calculated, and an expected deviation value with respect to a predetermined target level from the actual measurement value that is input to the input unit. It includes a calculating unit for calculating and a second calculating unit for calculating the blending ratio of the organic component that cancels the predicted deviation value based on the second correlation equation. Further, according to the present invention, there is provided a computer program configured to cause a computer to operate as the blending ratio determination device. As a result, calculation mistakes can be prevented, and even a worker who is not familiar with work can easily determine the blending ratio of organic components.

  The present invention also provides an electronic component including a conductive layer made of a fired body of the above-mentioned photosensitive composition. According to the above-mentioned photosensitive composition, even a conductive layer provided with fine line-shaped wiring can be stably realized. Therefore, according to the photosensitive composition, it is possible to preferably realize an electronic component having a small-sized and / or high-density conductive layer.

  The present invention also provides a paste-like photosensitive composition in which the photosensitive composition contains an organic dispersion medium. By preparing a paste, the photosensitive composition can be easily supplied to a desired position on the substrate in a desired form by means such as coating or printing.

It is a typical side view of a conductive film, (A) is a side view when using a conductive powder with a large average particle diameter, (B) is a side view when using a conductive powder with a large average particle diameter. is there. 6 is a flowchart of a manufacturing method according to an embodiment of the present invention. It is sectional drawing which shows the structure of a laminated chip inductor typically. It is a functional block diagram of a mixture ratio determination device. 5 is an example of a first correlation expression according to the first embodiment. It is an example of the 2nd correlation type | formula which concerns on a photoinitiator system. It is a graph which compared the solid line width. 9 is an example of a first correlation expression according to the second embodiment. 9 is an example of a first correlation expression according to the second embodiment. It is an example of the 2nd correlation type concerning an ultraviolet absorber. It is an example of the 2nd correlation type concerning a photopolymerization inhibitor.

  Hereinafter, preferred embodiments of the present invention will be described. Note that matters other than matters particularly referred to in the present specification and matters necessary for carrying out the present invention (for example, a method of forming a conductive film or a conductive layer, a method of manufacturing an electronic component, etc.) are described in the present specification. Can be understood on the basis of the technical contents taught by, and general common general knowledge of those skilled in the art. The present invention can be carried out based on the contents disclosed in this specification and the common general technical knowledge in the field.

  In the present specification, the "conductive film" refers to a film-like body (dried product) obtained by drying the photosensitive composition at a temperature not higher than the boiling point of the organic component (generally 200 ° C or lower, for example 100 ° C or lower). The conductive film includes all unbaked (before baking) film-like bodies. The conductive film may be an uncured product before photocuring or a cured product after photocuring. In addition, in the present specification, the “conductive layer” refers to a sintered body (baked product) obtained by baking the photosensitive composition at a sintering temperature of the conductive powder or higher. The conductive layer includes a wiring (linear body), a wiring pattern, and a solid pattern. Further, in the present specification, the notation of “A to B” indicating a range includes not only A or more and B or less but also “preferably larger than A” and “preferably smaller than B”.

<< Method for producing photosensitive composition >>
In the present embodiment, a manufacturing method in which the target level factor is the line width (targeting the line width) will be described from the background that the line width is particularly important as a required characteristic. That is, in the present embodiment, the predetermined target level is represented by "target line width", and the predicted deviation value is represented by "predicted deviation width". However, as will be described later, the factor of the target level is not limited to the line width as long as it is due to the light absorption degree or the light curing degree of the conductive film.

  FIG. 2 is a flowchart of the manufacturing method according to the present embodiment. The manufacturing method disclosed herein is a method for manufacturing a photosensitive composition containing a conductive powder in a predetermined compounding ratio. In this embodiment, the manufacturing method includes the following steps: (Step S1) average particle size measuring step; (Step S2) expected deviation width checking step; (Step S3) organic component blending ratio determining step; S4) preparing the photosensitive composition. Hereinafter, each step will be described in order.

<(Step S1) Average Particle Size Measuring Step>
In this step, first, a conductive powder used for producing the photosensitive composition is prepared. The conductive powder is a component that imparts electric conductivity to the conductive layer. As the conductive powder, a commercially available product may be purchased, or the conductive powder may be produced by a conventionally known method. The type of the conductive powder is not particularly limited, and from the conventionally known ones, one type can be used alone, or two or more types can be used in appropriate combination, depending on the application.

  Examples of the conductive powder include gold (Au), silver (Ag), copper (Cu), platinum (Pt), palladium (Pd), aluminum (Al), nickel (Ni), ruthenium (Ru), rhodium ( Rh), tungsten (W), iridium (Ir), osmium (Os), and other simple substances of metals, and mixtures and alloys thereof can be used. Examples of the alloy include silver alloys such as silver-palladium (Ag-Pd), silver-platinum (Ag-Pt), and silver-copper (Ag-Cu). In a preferred aspect, the conductive powder contains silver-based particles. Silver has relatively low cost and high electrical conductivity. Therefore, when the conductive powder contains silver particles, a conductive layer having an excellent balance between cost and low resistance can be realized. In addition, in this specification, "silver-based particles" include all particles including a silver component. Examples of silver-based particles include silver simple substance, the above-described silver alloy, core-shell particles having silver-based particles as a core, for example, silver-ceramic core-shell particles.

  An organic surface treatment agent may be attached to the surface of the conductive powder. The organic surface treatment agent, for example, improves the dispersibility of the conductive powder in the photosensitive composition, enhances the affinity between the conductive powder and other components, and oxidizes the surface of the metal forming the conductive powder. Can be used for at least one of: Examples of the organic surface treatment agent include fatty acids such as carboxylic acids and benzotriazole compounds.

  In a preferred embodiment, the electrically conductive powder comprises metal-ceramic core-shell particles. The metal-ceramic core-shell particle has a core portion containing a metal material, and a coating portion containing a ceramic material and coating at least a part of the surface of the core portion. The coating typically comprises a plurality of fine ceramic particles. The average particle diameter of the ceramic particles forming the coating portion is typically smaller than the average particle diameter of the metal material forming the core portion, for example, 1/1000 to 1/2 of the average particle diameter of the metal material, and further, It may be about 1/100 to 1/10. Ceramic materials have excellent chemical stability, heat resistance, and durability. Therefore, by adopting the morphology of the metal-ceramic core-shell particles, the stability of the conductive powder in the photosensitive composition can be better improved and a highly durable conductive layer can be realized. In addition, for example, in the application of manufacturing a ceramic electronic component by forming a conductive layer on a ceramic base material, it is possible to enhance the integrity with the ceramic base material, and it is preferable to remove or break the conductive layer after firing. Can be suppressed.

  Although not particularly limited, examples of the ceramic material forming 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), oxide materials such as barium titanate; composite oxide materials such as cordierite, mullite, forsterite, steatite, sialon, zircon, and ferrite. A nitride material such as silicon nitride (silicon nitride) and aluminum nitride (aluminum nitride); a carbide material such as silicon carbide (silicon carbide); a hydroxide material such as hydroxyapatite; For example, in the application for producing a ceramic electronic component by forming a conductive layer on a ceramic base material, a ceramic material having the same or excellent affinity as the ceramic base material is preferable. Although not particularly limited, the content ratio of the ceramic material in the core-shell particles may be 0.01 to 5.0 parts by mass with respect to 100 parts by mass of the metal material of the core part.

  Although not particularly limited, when a commercially available conductive powder is used, the average particle size (nominal value) of the conductive powder is, in consideration of exposure performance (for example, light absorption or photocurability). It may be approximately 0.1 to 10 μm. By setting the average particle size (nominal value) within the above range, it is possible to more stably form the thin wire wiring. From the viewpoint of suppressing the aggregation in the photosensitive composition and improving the storage stability of the photosensitive composition, the average particle diameter of the conductive powder (nominal value, for example, measurement by laser diffraction / scattering method or SEM observation And the like) may be, for example, 0.5 μm or more, 1 μm or more, 1.5 μm or more, 2 μm or more. Further, from the viewpoint of improving the fine wire forming property and promoting the densification and low resistance of the conductive layer, the average particle diameter (nominal value) of the conductive powder is, for example, 5 μm or less, 4.5 μm or less, It may be 4 μm or less.

  Although not particularly limited, the conductive powder typically has a spherical shape with an average aspect ratio of approximately 1 to 2, preferably 1 to 1.5, for example, 1 to 1.3. This makes it possible to more stably realize the exposure performance. In the present specification, the "average aspect ratio" means observing a plurality of conductive particles forming a conductive powder with an electron microscope, and calculating an arithmetic average value of the aspect ratio (long diameter / major axis). (Short diameter ratio). Further, in the present specification, the term “spherical” means that it can be regarded as a sphere (ball) as a whole, and may include an ellipse, a polygon, a disc sphere, and the like.

Although not particularly limited, the conductive powder preferably has a lightness L ^* of 50 or more in the L ^* a ^* b ^* color system based on JIS Z 8781: 2013. As a result, light can stably reach the deep portion of the uncured conductive film at the time of exposure, and for example, a thick conductive layer having a film thickness of 5 μm or more, and even 10 μm or more can be stably formed. can do. From the above viewpoint, the brightness L ^* of the conductive powder may be approximately 55 or more, for example, 60 or more. The lightness L ^* can be measured with a spectrocolorimeter conforming to JIS Z 8722: 2009, for example.

  In this step, next, the average particle size of the conductive powder used is measured. The measuring method of the average particle diameter, the measuring device and the measuring conditions, and the analysis condition of the measurement result may be the same as those at the time of calculating the first correlation equation described later. As a result, it is possible to improve the prediction accuracy in the subsequent step of confirming the predicted deviation width (step S2). In one example, particle size distribution measurement is performed using a particle size distribution measuring device based on the laser diffraction / scattering method. For example, by using the Microtrac MT-3000II series manufactured by Microtrac Bell Co., Ltd., it is possible to measure a particle size range of approximately 0.02 to 2800 μm. The particle size distribution measurement gives a volume-based particle size distribution of the conductive powder. Then, in the particle size distribution, the particle size (D50 particle size) corresponding to the integrated value 50% from the smaller particle size side is defined as the “average particle size (actual measurement value)”. As described above, the average particle size (actual measurement value) of the conductive powder used for producing the photosensitive composition is obtained.

<(Step S2) Step of confirming expected deviation>
In this step, first, the first correlation equation is prepared. The first correlation equation is prepared in advance for each type of conductive powder (for example, for each product name). In the first correlation equation, the correlation coefficient R ² is generally 0.85 or more, preferably 0.9 or more, for example 0.92 or more. The first correlation equation can be prepared, for example, as follows.

That is, first, a plurality of conductive powders having different manufacturing lots and / or average particle diameters (nominal values) are prepared. At this time, physical properties other than the particle diameters of the plurality of conductive powders, for example, the metal species of the conductive powder, the average aspect ratio, and the brightness that can have a comparatively large influence on the exposure performance (for example, light absorption or photocurability). By making the conditions for L ^{* and the} like uniform (substantially the same), bias other than the particle size can be removed, and the effect of the particle size itself can be evaluated clearly. Next, the average particle diameters of the prepared conductive powders are individually measured. The average particle diameter can be measured by a conventionally known measuring method. For example, it can be performed using a particle size distribution measuring device based on the laser diffraction / scattering method.

  Next, a photosensitive composition is prepared using a plurality of conductive powders whose average particle diameters have been measured. For example, first, a predetermined vehicle containing an organic component is prepared, and a conductive powder is dispersed therein to prepare a photosensitive composition. Thereby, a plurality of photosensitive compositions in which the components other than the conductive powder and the compounding ratio thereof are unified and only the kind of the conductive powder is different are prepared. Next, each of the prepared photosensitive compositions is applied onto a substrate and photocured and etched. As a result, fine line-shaped wiring is formed.

  Next, the wiring on the base material is observed, and the line width of the wiring is measured from the obtained observation image. A laser microscope, for example, can be used to observe the wiring. At this time, the line width is measured for a plurality of fields of view, and the arithmetic mean value thereof is taken as the real line width (actual line width). Then, for example, the data is plotted in a graph of "average particle size (measured value) X-solid line width Y" in which the horizontal axis X is the average particle size (measured value) of the conductive powder and the vertical axis Y is the solid line width. To do. From this graph, a correlation formula between the average particle diameter (actual measurement value) and the solid line width is calculated. In this way, the first correlation equation is prepared.

  In this step, next, the actual measurement value obtained in step S1 is compared with the first correlation equation relating to the same type of conductive powder. Then, the expected deviation width (predicted deviation width) with respect to the predetermined target line width is confirmed. For example, first, the actual measurement value obtained in step S1 is interpolated into the correlation formula between the average particle diameter (actual measurement value) and the solid line width to calculate the expected line width. Then, the difference between the expected line width and the desired target line width is calculated as the expected deviation width. The target line width can be set arbitrarily. In this way, the expected deviation width is confirmed.

<(Step S3) Organic Component Mixing Ratio Determination Step>
In this step, first, the second correlation equation is prepared. The second correlation equation is prepared in advance for each type of conductive powder (for example, for each product name). In the second correlation equation, the correlation coefficient R ² is generally 0.85 or more, preferably 0.9 or more, for example 0.92 or more. The second correlation equation may be represented by a linear function. In a linear function, two variables are in proportional relation. Therefore, the blending ratio can be calculated simply and easily. The second correlation equation can be prepared, for example, as follows. That is, first, at least one of the organic components used for producing the photosensitive composition is prepared. For example, at least one of the organic components contained in the vehicle used when calculating the first correlation formula is prepared. The organic component to be prepared may be of one type, or of two or more types, for example.

  Although not particularly limited, the organic component prepared at this time is a component that affects the curing rate of the photosensitive composition, such as an organic binder and a photocurable compound other than the light-absorbing property of the photosensitive composition and It is preferable to include an organic component (curing speed adjusting agent) that adjusts at least one of photopolymerizability. The organic component to be prepared may include at least one of (A) photopolymerization initiator, (B) sensitizer, (C) light absorber, and (D) polymerization inhibitor. Among them, it is preferable to include a polymerization initiator system, that is, at least one of (A) a photopolymerization initiator and (B) a sensitizer. The organic component to be prepared may be, for example, the first component having the highest compounding ratio in the vehicle among the components (A) to (D), or may further include the second component having the second highest compounding ratio. ..

  The photopolymerization initiator (A) is a component that decomposes upon irradiation with light to generate active species such as radicals and cations to promote the polymerization reaction of the photocurable component. The photopolymerization initiator is a component that adjusts the photopolymerizability of the photosensitive composition (specifically, accelerates the polymerization reaction). As the photopolymerization initiator, from among conventionally known photopolymerization initiators, one kind may be used alone, or two or more kinds may be appropriately combined and used depending on the kind of the photocuring component. The photopolymerization initiator may be a photoradical polymerization initiator, a photocationic polymerization initiator or a photoanionic polymerization initiator. In particular, a photoradical polymerization initiator is preferable because it has a high reaction rate and does not require heat curing. As a typical example, a benzoin-based photopolymerization initiator, an α-hydroxyacetophenone-based photopolymerization initiator, an α-aminoalkylphenone-based photopolymerization initiator, a benzyl ketal-based photopolymerization initiator, an α-hydroxyacetophenone-based photopolymerization initiator, α-aminoacetophenone photopolymerization initiator, acylphosphine oxide photopolymerization initiator, titanocene photopolymerization initiator, 0-acyl oxime photopolymerization initiator, oxime ester photopolymerization initiator, benzophenone photopolymerization initiator , And acridine-based photopolymerization initiators.

  The (B) sensitizer (also referred to as an accelerator or a reaction accelerator) is a component that transmits energy obtained by absorbing light to the photocuring component to accelerate the polymerization reaction of the photocuring component. The sensitizer is a component that adjusts the photopolymerizability of the photosensitive composition (specifically, accelerates the polymerization reaction). As the sensitizer, from among conventionally known sensitizers, one kind may be used alone, or two or more kinds may be appropriately combined and used, depending on the wavelength of light to be irradiated. Typical examples include anthracene sensitizers, aromatic ketone sensitizers, biphenyl sensitizers, anthraquinone sensitizers and the like.

  The (C) light absorber (also referred to as a colorant or an organic pigment) is a component that adjusts the light absorbency of the photosensitive composition. The light absorber is a component that typically changes the color of the photosensitive composition to adjust the light penetration rate. The light absorbing agent may be an ultraviolet absorbing agent that partially or wholly absorbs light having a wavelength of ultraviolet rays, or may be an infrared absorbing agent that partially or completely absorbs light having an infrared wavelength. It may be a visible light absorbing agent (for example, a black colorant) that partially or wholly absorbs light having a wavelength. As the light absorber, one selected from conventionally known ones may be used alone or in combination of two or more, depending on the wavelength range of the light to be irradiated. Typical examples are benzotriazole-based light absorbers, triazine-based light absorbers, benzophenone-based light absorbers, benzoate-based light absorbers, salicylate-based light absorbers, cyanoacrylate-based light absorbers, resorcinol-based light absorbers, hindered amines. Examples include light absorbers.

  In particular, when an ultraviolet absorber is exposed to ultraviolet light, the light that has penetrated into the inside of the conductive film from the opening of the photomask is scattered and the light-shielding portion of the photomask is cured, and the line width becomes thicker than the opening width of the photomask. It has the effect of reducing the phenomenon.

  As the ultraviolet absorber, those having a high absorption coefficient in the wavelength range of 250 to 520 nm are preferable, and among them, organic dyes having a high absorption coefficient in the wavelength range of 350 to 450 nm are preferable. Examples of the organic dye include azo type, benzophenone type, aminoketone type, xanthene type, quinoline type, aminoketone type, anthraquinone type, diphenyl cyanoacrylate type, triazine type and p-aminobenzoic acid type. Of these, azo-based and benzophenone-based organic dyes are preferable.

  Examples of the azo-based organic dye include Sudan Blue, Sudan R, Sudan II, Sudan III, Sudan IV, Oil Orange SS, Oil Violet, Oil Yellow OB and the like. Examples of the benzophenone-based organic dye include Ubinal (registered trademark) D-50 (2,2 ′, 4,4′-tetrahydroxybenzophenone) manufactured by BASF, and Ubinal (registered trademark) MS40 (2-hydroxy-4). -Methoxybenzophenone 5-sulfonic acid), Ubinal (registered trademark) DS49 (2,2-dihydroxy-4,4'-dimethoxybenzophenone-5,5'-disulphonic acid sodium salt) and the like.

  The (D) polymerization inhibitor (also referred to as an inhibitor, a light stabilizer, a stabilizer, a radical scavenger, an oxygen scavenger, etc.) inhibits the polymerization reaction of the photocurable component to give the photosensitive composition weather resistance. , A component that improves at least one of heat resistance and storage stability. The polymerization inhibitor is a component that adjusts the photopolymerizability of the photosensitive composition (specifically, slows down the polymerization reaction). As the polymerization inhibitor, one kind may be used alone or two or more kinds may be appropriately combined and used from among conventionally known polymerization inhibitors. Typical examples include hydroquinone and its derivatives, and phenol derivatives.

  Next, a predetermined conductive powder is used to stepwise change the compounding ratio of the prepared organic components to prepare a plurality of photosensitive compositions. Next, similarly to the calculation of the first correlation equation, the prepared photosensitive compositions are applied onto the respective substrates, and photocuring and etching are performed. As a result, fine line-shaped wiring is formed. Next, the wiring on the base material is observed with a laser microscope, and the line width of the wiring is measured from the obtained observation image. At this time, the line width is measured for a plurality of fields of view, and the arithmetic mean value thereof is taken as the real line width (actual line width). Then, for example, data is plotted in a graph of "mixing ratio of organic components X-solid line width Y" in which the horizontal axis X represents the mixing ratio of organic components in the photosensitive composition and the vertical axis Y represents the solid line width. From this graph, the correlation equation between the blending ratio of the organic components and the solid line width is calculated. In this way, the second correlation equation is prepared.

  In this step, next, using the second correlation equation, the compounding ratio of the organic components in the photosensitive composition is determined so as to cancel the expected deviation width confirmed in step S2. In other words, the blending ratio of the organic components in the photosensitive composition is determined so as to induce the target line width. In one example, the vehicle formulation used when calculating the first correlation equation is used as the base. Then, the compounding ratio is changed from the base vehicle for at least one of the organic components for which the second correlation equation has been calculated. As a result, the expected deviation width confirmed in step S2 can be canceled. The organic component whose compounding ratio is not changed may be the same as that of the base vehicle. The organic component for which the blending ratio is changed may be one kind, or, for example, when the expected deviation width is large, by slightly changing the blending ratio of two or more kinds of organic components, it is possible to predict the total as a whole. The deviation width may be canceled.

  For example, in the case of canceling the expected deviation width using the polymerization initiator system, first, as the second correlation expression, a correlation expression between the compounding ratio of the polymerization initiator system and the solid line width is prepared. For example, two formulas are prepared: a correlation formula between the compounding ratio of the photopolymerization initiator and the solid line width, and a correlation formula between the compounding ratio of the sensitizer and the solid line width. In this correlation equation, it is assumed that the compounding ratio of the polymerization initiator system and the solid line width have a positive correlation. In this case, if the expected line width is larger than the target line width, the compounding ratio of the polymerization initiator system is reduced from the compounding of the base vehicle based on the correlation formula so as to cancel the expected deviation. On the other hand, when the expected line width is smaller than the target line width, the compounding ratio of the polymerization initiator system is increased based on the correlation formula so as to cancel the expected deviation width from the base vehicle compound.

  Further, for example, when canceling the expected deviation width by using the polymerization inhibitor, first, as the second correlation expression, a correlation expression between the compounding ratio of the polymerization inhibitor and the solid line width is prepared. In this correlation equation, it is assumed that the compounding ratio of the polymerization inhibitor and the solid line width have a negative correlation. In this case, if the expected line width is larger than the target line width, the compounding ratio of the polymerization inhibitor is increased based on the correlation formula so as to cancel the expected deviation width from the compounding of the base vehicle. Further, if the expected line width is smaller than the target line width, the compounding ratio of the polymerization inhibitor is reduced based on the correlation formula so as to cancel the expected deviation width from the compounding of the base vehicle. As described above, the compounding ratio of the organic component in the photosensitive composition is determined.

  The organic components for adjusting the blending ratio in this step are not limited to the components (A) to (D) described above. For example, the compounding ratio of at least one of a photocurable resin and a photocurable compound described below may be adjusted as long as other properties (for example, tackiness of the conductive film with respect to the base material) are not significantly deteriorated. Further, for example, the compounding ratio of other additive components described below may be adjusted.

<(Step S4) Step of Preparing Photosensitive Composition>
In this step, the photosensitive composition is prepared using the conductive powder whose average particle diameter was measured in step S1. For example, first, an organic dispersion medium, an organic binder, a photocurable compound, a photopolymerization initiator, a sensitizer, a light absorber, a polymerization inhibitor, and other additive components used as necessary. Mix in to prepare liquid vehicle. At this time, each component is added so that the photosensitive composition has the compounding ratio determined in step S3. Next, the conductive powder and the vehicle are mixed in a predetermined compounding ratio. Thereby, the photosensitive composition is prepared. In the present embodiment, a photosensitive composition (paste-like photosensitive composition) containing an organic dispersion medium and prepared in a paste form (including a slurry form and an ink form) can be obtained.

The organic binder (polymer component) is a component that enhances the adhesiveness between the base material and the uncured conductive film. The organic binder may or may not have photosensitivity (refers to a property of chemically or structurally changing by light. For example, photocurability). The organic binder includes a photopolymerizable oligomer (prepolymer) having a weight average molecular weight of 2000 or more and less than 5000 and a photopolymerizable polymer having a weight average molecular weight of 5000 or more. As the organic binder, one can be used alone or two or more can be appropriately used from among conventionally known ones, depending on the type of the base material, the photopolymerizable compound, the photopolymerization initiator, and the like. .. The organic binder is preferably one that can be easily removed with a developing solution in the developing step. For example, when an alkaline developer is used in the developing step, a hydroxyl group (-OH), a carboxyl group (-C (= O) OH), an ester bond (-C (= O) O-), a sulfo group. of _(-SO 3 H) or the like, a compound having a structural part showing acidity are preferable. This makes it difficult for the residue to remain in the unexposed portion, and for example, the space between the fine lines can be stably secured.

  Examples of suitable organic binders include cellulosic polymers such as methyl cellulose, ethyl cellulose, carboxymethyl cellulose, and hydroxymethyl cellulose, acrylic resins, phenol resins, alkyd resins, polyvinyl alcohol, polyvinyl butyral, and the like. Of these, hydrophilic organic binders such as cellulose-based polymers and acrylic resins are preferable from the viewpoint of easy removal in the developing step.

  A photo-curable resin may be used as the organic binder. The photocurable resin is a photocurable component that is polymerized and cured by the active species generated from the photopolymerization initiator. The photocurable resin typically has at least one of an unsaturated bond and a cyclic structure. As the photo-curable resin, one kind can be used alone or two or more kinds can be appropriately combined and used from the conventionally known ones. As a typical example, a resin having an ethylenic double bond such as a (meth) acryloyl group, a vinyl group or an allyl group, for example, an acrylic resin or an epoxy resin can be mentioned. In addition, in this specification, "(meth) acryloyl" is a term including "methacryloyl" and "acryloyl".

  Specific examples of the acrylic resin include homopolymers of alkyl (meth) acrylates such as polymethyl (meth) acrylate, polyethyl (meth) acrylate, and polybutyl (meth) acrylate, and alkyl (meth) acrylate as a main monomer (the largest mass ratio). As a monomer), a copolymer containing a sub-monomer having copolymerizability in the main monomer can be mentioned.

  The photocurable compound (monomer component) is a photocurable component that is polymerized and cured by active species generated from a photopolymerization initiator. The polymerization reaction may be, for example, addition polymerization or ring-opening polymerization. The photocurable compound may be radically polymerizable or cationically polymerizable. The photocurable compound is a monomer having a weight average molecular weight of less than 2000. As the photocurable compound, one can be used alone, or two or more can be appropriately combined and used from the conventionally known compounds. A typical example is a (meth) acrylate monomer having a (meth) acryloyl group. The (meth) acrylate monomer includes a monofunctional (meth) acrylate having one functional group per molecule, a polyfunctional (meth) acrylate having two or more functional groups per molecule, and modified products thereof. To do. Specific examples of the (meth) acrylate monomer include polyfunctional (meth) acrylate, urethane-modified (meth) acrylate having a urethane bond, epoxy-modified (meth) acrylate, and silicone-modified (meth) acrylate. In addition, in this specification, "(meth) acrylate" is a term including "methacrylate" and "acrylate".

  The organic dispersion medium is a component that imparts appropriate viscosity and fluidity to the photosensitive composition to improve the handleability of the photosensitive composition and the workability when molding a conductive film. As the organic dispersion medium, one type may be used alone or two or more types may be appropriately combined and used from among conventionally known organic dispersion media. Typical examples include organic solvents such as alcohol solvents, glycol solvents, ether solvents, ester solvents, hydrocarbon solvents and mineral spirits. Among them, an organic solvent having a boiling point of 150 ° C. or higher, more preferably 170 ° C. or higher, is preferable from the viewpoint of improving the storage stability of the photosensitive composition and the handling property when forming a conductive film. Further, as another preferable example, an organic solvent having a boiling point of 250 ° C. or lower, and more preferably an organic solvent having a boiling point of 220 ° C. or lower are preferable from the viewpoint of suppressing the drying temperature after printing the conductive film to be low.

As the other additive components, one type may be used alone or two or more types may be appropriately combined and used among conventionally known components. As an example, antioxidants, plasticizers, surfactants, leveling agents, thickeners, wetting agents, dispersants, defoamers, antistatic agents, anti-gelling agents, preservatives, fillers (organic or inorganic fillers ), Glass powder, ceramic powder (Al ₂ O ₃ , ZrO ₂ , SiO _{2 and the} like), organometallic compounds (metal resinate), and the like.

  In this embodiment, the compounding ratio of the conductive powder in the photosensitive composition is predetermined. Although not particularly limited, the compounding ratio of the conductive powder may be approximately 50% by mass or more, typically 60 to 95% by mass, for example 70 to 90% by mass. By satisfying the above range, a conductive layer having high density and high electrical conductivity can be formed. In addition, the handleability of the photosensitive composition and the workability when molding the conductive film can be improved.

  Although not particularly limited, the proportion of the polymerization initiator system in the entire photosensitive composition is generally 5% by mass or less, typically 0.01 to 1% by mass, for example 0.02 to 0.5. It may be mass%, 0.05 to 0.2 mass%. Further, the proportion of the light absorber may be approximately 0.5% by mass or less, typically 0.1% by mass or less, for example 0.01% by mass or less, and further 0.001% by mass or less. The proportion of the polymerization inhibitor may be about 0.5% by mass or less, typically 0.1% by mass or less, for example 0.001% by mass or less. Further, the proportion of the photocurable resin in the entire photosensitive composition is generally 5% by mass or less, typically 0.01 to 1% by mass, for example 0.02 to 0.5% by mass, 0.03 to. It may be 0.2% by mass. The proportion of the photocurable compound in the entire photosensitive composition is generally 5% by mass or less, typically 0.01 to 1% by mass, for example 0.02 to 0.5% by mass, 0.03 to. It may be 0.2% by mass. Moreover, the compounding ratio of the photocurable resin and the photocurable compound may be approximately 1:10 to 10: 1, for example, 1: 3 to 3: 1, and further 1: 2 to 2: 1. The proportion of the organic dispersion medium may be approximately 1 to 50% by mass, typically 3 to 30% by mass, for example 5 to 20% by mass. In addition, the ratio of other additive components may be approximately 5% by mass or less, for example, 3% by mass or less.

<< Application of Photosensitive Composition >>
According to the photosensitive composition disclosed herein, a conductive layer having L / S finer than 30 μm / 30 μm and further finer L / S smaller than 20 μm / 20 μm can be stably formed. Therefore, the photosensitive composition disclosed herein can be suitably used for forming a conductive layer in various electronic components such as an inductance component, a capacitor component, and a multilayer circuit board. The electronic component may be of various mounting forms such as a surface mounting type and a through hole mounting type. The electronic component may be a laminated type, a wire wound type, or a thin film type. Typical examples of the inductance component include a high frequency filter, a common mode filter, a high frequency circuit inductor (coil), a general circuit inductor (coil), a high frequency filter, a choke coil, and a transformer.

  Further, the photosensitive composition in which the conductive powder contains metal-ceramic core-shell particles can be suitably used for forming a conductive layer of a ceramic electronic component. In the present specification, the “ceramic electronic component” includes all electronic components having an amorphous ceramic base material (glass ceramic base material) or a crystalline (that is, non-glass) ceramic base material. As a typical example, a high frequency filter having a ceramic base material, a ceramic inductor (coil), a ceramic capacitor, a low temperature co-fired ceramics substrate (LTCC base material), a high temperature co-fired ceramic base material ( High Temperature Co-fired Ceramics Substrate: HTCC base material) and the like.

  FIG. 3 is a cross-sectional view schematically showing the structure of the laminated chip inductor 10. The dimensional relationship (length, width, thickness, etc.) in FIG. 3 does not necessarily reflect the actual dimensional relationship. In addition, reference numerals X and Y in the drawings represent a horizontal direction and a vertical direction, respectively. However, this is only a direction for convenience of description.

  The multilayer chip inductor 10 includes a main body 11 and external electrodes 20 provided on both side surfaces of the main body 11 in the left-right direction X. The shape of the multilayer chip inductor 10 is, for example, 1608 shape (1.6 mm × 0.8 mm), 2520 shape (2.5 mm × 2.0 mm), or the like. The main body 11 has a structure 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, a ceramic material as described above as a material that can form a coating portion of conductive powder. The internal electrode layers 14 are arranged between the ceramic layers 12 in the vertical direction Y. The internal electrode layer 14 is formed using the photosensitive composition described above. The internal electrode layers 14 that are adjacent to each other in the up-down direction Y with the ceramic layer 12 sandwiched therebetween are electrically connected via the vias 16 provided in the ceramic layer 12. As a result, the internal electrode layer 14 has 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 10 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 this 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 ceramic layer forming green sheets. Then, via holes are appropriately formed at predetermined positions of the plurality of ceramic layer forming green sheets by using a punching machine or the like. Next, using the above-mentioned photosensitive composition, a conductive film having a predetermined coil pattern is formed at predetermined positions on the plurality of ceramic layer forming green sheets. As an example, the following steps: (Step A) a step of forming a conductive film composed of a dried body of the photosensitive composition by applying the photosensitive composition onto a ceramic layer-forming green sheet and drying it; B) A step of covering the conductive film with a photomask having a predetermined opening pattern, exposing through the photomask, and partially photo-curing the conductive film: (Step C) not etching the conductive film after photo-curing A conductive film in an unbaked state can be formed by a manufacturing method including a step of removing a cured portion.

  Incidentally, in forming a conductive film using the above-mentioned photosensitive composition, a conventionally known method can be appropriately used. For example, in (Step A), the application of the photosensitive composition can be performed using various printing methods such as screen printing or a bar coater. The photosensitive composition is typically dried at 50 to 100 ° C. In step (B), exposure can be performed using an exposure device that emits radiation such as visible light, ultraviolet light, X-rays, electron beams, α rays, β rays, and γ rays. As an example, an exposure device that emits light in the wavelength range of 10 to 400 nm, for example, an ultraviolet irradiation lamp such as a high pressure mercury lamp, a metal halide lamp, or a xenon lamp can be used. In (Step C), an aqueous solution containing an alkaline component such as sodium hydroxide or sodium carbonate can be used for etching.

  Next, a plurality of green sheets for forming a ceramic layer on which an unfired conductive film is formed are stacked and pressure-bonded. In this way, a laminate of unfired ceramic green sheets is produced. Next, the laminated body of ceramic green sheets is fired at, for example, 600 to 1000 ° C. As a result, the ceramic green sheet is integrally sintered to form the main body 11 including the ceramic layer 12 and the internal electrode layer 14 made of a fired body of the photosensitive composition. Then, an appropriate external electrode forming paste is applied to both ends of the main body 11 and baked to form the external electrodes 20. In this way, the laminated chip inductor 10 can be manufactured.

≪Compounding ratio determination device≫
FIG. 4 is a functional block diagram of the mixture ratio determination device 30. The mixture ratio determination device 30 disclosed herein includes an input unit 31, a storage unit 32, a first calculation unit 33, a second calculation unit 34, and a display unit 35. Each unit of the mixture ratio determination device 30 is configured to be able to communicate with each other. Each part of the mixture ratio determination device 30 may be configured by software or hardware. Each part of the blending ratio determination device 30 may be implemented by a processor or may be incorporated in a circuit.

The input unit 31 accepts an operation input from a user (for example, an operator who prepares a photosensitive composition), and can input the type and average particle size (measured value) of the conductive powder to be used, and a target line width. Is configured. When a plurality of conductive powders are used in combination, the mixing ratio of them can be further input. The type of conductive powder is information represented by, for example, a purchaser, an item name (product name), a product number, and the like. The type of conductive powder is, for example, information represented by physical properties such as the structure of the conductive powder (whether or not it has a core-shell structure), the average particle size (nominal value), the average aspect ratio, and the brightness L ^*. Good. The input unit 31 includes, for example, a keyboard provided with cursor keys and numeral input keys, a pointing device such as a mouse, and an input device (not shown) such as a button. The input unit 31 may be configured so that the type of conductive powder can be selected from the pull-down menu displayed on the display unit 35, for example. The input unit 31 may be configured to be able to capture the above-described information from, for example, an external device such as a host computer or a network connected by wire or wirelessly. In the present embodiment, the "target line width" is an example of a predetermined target level.

  The storage unit 32 stores the first correlation equation and the second correlation equation. The first correlation equation and the second correlation equation are stored in advance in the storage unit 32 for each type of conductive powder (for example, for each product name). Therefore, there are typically a plurality of first correlation equations and a plurality of second correlation equations stored in the storage unit 32. The first correlation equation may be represented by a linear function. Although not particularly limited, the first correlation equation is, for example, the above-described correlation equation between the average particle size (measured value) of the conductive powder and the solid line width. The second correlation equation has a predetermined slope (change rate). The second correlation equation may be represented by a linear function. Although not particularly limited, the second correlation equation is, for example, a correlation equation between the compounding ratio of the above-mentioned organic component (for example, a polymerization initiator system) and the solid line width. The storage unit 32 may further store the composition of the base vehicle, that is, the type and blending ratio of each organic component contained in the vehicle.

  When the user inputs the type of the conductive powder to be used and the average particle size (measured value) from the input unit 31, the first calculation unit 33 stores the first correlation stored in the storage unit 32. Among the formulas, the first correlation formula relating to the conductive powder of the same kind as the input conductive powder is referred to. Then, the expected deviation width with respect to the target line width is calculated from the average particle diameter (measured value) input to the input unit 31. For example, when the first correlation equation is represented by the correlation equation between the average particle size (measured value) of the conductive powder and the solid line width, first the average particle size (measured value) input to the input unit 31 is used. The expected line width is calculated by interpolating into the first correlation equation. Then, the difference between the expected line width and the target line width input by the user from the input unit 31 is calculated as the expected deviation width. It should be noted that in the present embodiment, the “expected shift width” is an example of a predicted shift value.

  When the expected shift width is calculated by the first calculation unit 33, the second calculation unit 34 calculates the conductivity of the same type as the input conductive powder from the second correlation equation stored in the storage unit 32. Refer to the second correlation equation relating to the powder. Then, the blending ratio of the organic components is calculated based on the expected deviation width calculated by the first calculating unit 33. For example, when the second correlation equation is represented by the correlation equation between the compounding ratio of the polymerization initiator system and the solid line width, the expected deviation width is divided by the slope of the second correlation expression to cancel the expected deviation width. The blending ratio of the polymerization initiator system is calculated. Then, the compounding ratio for canceling the expected deviation width is increased or decreased from the compounding ratio of the photopolymerization initiator system contained in the vehicle to obtain the final compounding ratio.

  The mixture ratio determination device 30 is, for example, a computer, and stores an interface (I / F) for a user, a central processing unit (CPU) that executes a command of a control program, and a program that the CPU executes. A read only memory (ROM), a random access memory (RAM) used as a working area for developing a program, and a storage device such as a memory for storing the program and various data. The blending ratio determination device 30 may be a computer program configured to cause a CPU of a computer to operate as each unit of the blending ratio determination device 30. The computer program may be a computer-readable recording medium in which the operation of the blending ratio determination device 30 is written.

  As the recording medium, for example, a semiconductor recording medium (for example, ROM, non-volatile memory card), an optical recording medium (for example, DVD, MO, MD, CD, BD), a magnetic recording medium (for example, magnetic tape, flexible disk). Etc. are illustrated. Further, the computer program can be transmitted to the server computer via the recording medium or a network such as the Internet or an intranet. In this case, the server computer is also one form of the mixing ratio determination device 30.

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

<Example 1: When using one kind of conductive powder alone>
Hereinafter, a case of producing a photosensitive composition by using one type of conductive powder alone will be described. Here, as a preliminary preparation, first, a first correlation equation and a second correlation equation corresponding to the conductive powder to be used were prepared. Specifically, the first correlation equation shown in FIG. 5 and the second correlation equation shown in FIG. 6 were prepared. FIG. 6 is a second correlation equation for adjusting the compounding ratio of the photopolymerization initiator system.

  The first correlation equation shown in FIG. 5 is prepared as follows. That is, first, as the conductive powder, a plurality (15 kinds here) of commercially available silver powders having an average particle diameter (nominal value) of about 3 μm were prepared. Next, using a particle size distribution analyzer based on laser diffraction / scattering method (Model “MT-3000II” manufactured by Microtrac Bell Co., measurement range: 0.02 to 2800 μm), wet measurement in a dispersion solvent The average particle diameters of 15 kinds of silver powder were measured by. As the dispersion solvent, an alcohol solvent (specifically, ethanol) was used from the viewpoint of suppressing the aggregation of the silver powder and dispersing the individual particles in the dispersion solvent. And the volume-based particle size distribution was obtained. The particle size distribution was typically monomodal with only one mode diameter (modal particle diameter). From the particle size distribution, the average particle size (measured value) of each of the 15 types of silver powder was read.

  Next, an organic binder, a photocurable compound, a photopolymerization initiator, a sensitizer, an ultraviolet absorber as a light absorber, and a polymerization inhibitor were added to the organic dispersion medium in the composition shown in Table 1. It was dissolved and a vehicle was prepared. Next, the above-prepared 15 kinds of silver powder and the vehicle were mixed in a mass ratio of 77:23 to prepare photosensitive compositions, respectively.

Next, each of the prepared photosensitive compositions was applied onto a commercially available ceramic green sheet by screen printing. Next, this was dried at 60 ° C. for 15 minutes to form a conductive film (solid film) on the green sheet (conductive film forming step). Next, a photomask was covered over the conductive film. A photomask having L / S = 25 μm / 25 μm was used. With the photomask covering the conductive film, the conductive film was partially cured by irradiating it with light having an intensity of 2500 mJ / cm ² by an ultraviolet exposure device (exposure step). After the exposure, a 0.4 mass% Na ₂ CO ₃ aqueous solution was sprayed on the ceramic green sheet to remove the uncured conductive film portion by etching, followed by washing with pure water and drying at room temperature (developing step). Thus, the wiring pattern was formed on the ceramic green sheet.

  Next, the wiring pattern was observed with a laser microscope, and the line width of the wiring was measured from the obtained observation image. The line width was measured for a plurality of visual fields, and the arithmetic mean value thereof was taken as the real line width (actual line width). Then, as shown in FIG. 5, the correlation between the average particle diameter (actual measurement value) of 15 kinds of silver powder and the solid line width is shown in a graph, and the correlation equation (Y = 5.593X + 11.192) is calculated. In the first correlation equation shown in FIG. 5, the average particle diameter (measured value) of the silver powder is proportional to the solid line width using the photosensitive composition containing the silver powder (correlation coefficient: 0.92). is doing. The first correlation equation shown in FIG. 5 is represented by a linear function. In FIG. 5, the average particle diameter (measured value) and the solid line width have a positive correlation. That is, the line width linearly increases as the average particle size (measured value) of the silver powder increases.

  The second correlation equation of FIG. 6 is prepared as follows. That is, first, a predetermined silver powder was prepared as the conductive powder. Further, the organic binder, the photocurable compound, the photopolymerization initiator, the sensitizer, the ultraviolet absorber, the polymerization inhibitor, and the organic dispersion medium are mixed in the mixing ratio shown in Table 1 above. I prepared a base vehicle. Next, the silver powder and the vehicle were mixed at a mass ratio of 77:23 to prepare a base photosensitive composition.

  Next, the compounding ratio of the photopolymerization initiator system (photopolymerization initiator and sensitizer) was changed as shown in Table 2 from the base photosensitive composition. At this time, the amount by which the compounding ratio of the photopolymerization initiator system was increased or decreased was adjusted by increasing or decreasing the amount of the organic dispersion medium. For example, when the compounding ratio of the photopolymerization initiator system was reduced from 0.550 to 0.515, the amount of the organic dispersion medium was increased by that amount (0.035). A plurality of such photosensitive compositions (here, 5 patterns) were prepared. Note that, when the compounding ratio of the photopolymerization initiator system was changed, the ratio of the photopolymerization initiator and the sensitizer was kept constant. Next, using the plurality of photosensitive compositions prepared above, a wiring pattern was formed in the same manner as in the calculation of the first correlation equation described above, and the solid line width was obtained. Then, the correlation between the compounding ratio of the photopolymerization initiator and the solid line width in the photosensitive composition having 5 patterns was shown in a graph, and the correlation equation (Y = 74.927X + 19.762) was calculated.

  In the second correlation formula of FIG. 6, the compounding ratio of the polymerization initiator system in the photosensitive composition and the solid line width are proportional (correlation coefficient: 0.96). The second correlation equation in FIG. 6 is represented by a linear function. In FIG. 6, the compounding ratio of the polymerization initiator system and the solid line width have a positive correlation. That is, it can be seen that the line width linearly increases as the blending ratio of the polymerization initiator system increases.

  In Example 1, after aligning the first correlation equation and the second correlation equation as described above, a silver powder (average particle diameter (nominal value): 3 μm) used in the photosensitive composition is prepared in step S1. did. Next, the average particle size of the silver powder was measured under the same measurement and analysis conditions using the same particle size distribution measuring device as that used in the calculation of the first correlation equation. Then, the average particle size (measured value) of the silver powder was read from the volume-based particle size distribution. Here, the actually measured value was 3.17 μm.

  Next, in step S2, the actually measured value obtained in step S1 was compared with the first correlation expression in FIG. Then, the expected deviation width with respect to the predetermined target line width was confirmed. Here, by interpolating the measured value of 3.17 μm into the first correlation equation (Y = 5.593X + 11.192) of FIG. 5, the expected line width is calculated as 28.92 μm. Therefore, when the target line width is 27.3 μm, the expected shift width is (expected line width 28.92 μm) − (target line width 27.3 μm), and is calculated to be +1.62 μm. That is, it can be seen that when the photosensitive composition is prepared with the composition of the vehicle as it is, the line width of 1.62 μm from the target line width is likely to be thickened.

  Therefore, next, in step S3, the blending ratio of the organic components is changed so as to cancel the expected deviation width and bring it closer to the target line width. Here, the compounding ratio of the polymerization initiator system was adjusted based on the second correlation formula (Y = 74.927X + 19.762) in FIG. That is, the value obtained by dividing the expected deviation width +1.62 μm by the slope 74.927 of the second correlation formula (= 1.62 / 74.927) = + 0.022 is the amount of the polymerization initiator system for adjusting the expected deviation width +1.62 μm. Becomes Therefore, the proportion of the polymerization initiator system was reduced from the base photosensitive composition by 0.022% by mass in order to cancel the expected deviation width. Table 3 is an example of the compounding ratio of the polymerization initiator system determined in consideration of the expected deviation width.

  Next, as step S4, a vehicle was prepared in which the compounding ratio of the polymerization initiator system was changed as shown in Table 3. The organic components not shown in Table 3, such as the organic binder, the photocurable compound, the ultraviolet absorber, and the polymerization inhibitor, are the same as those in the photosensitive composition as the base. Next, the silver powder whose average particle size was measured in step S1 and the vehicle were mixed to prepare a photosensitive composition. Then, a wiring pattern was formed and the solid line width was measured. As a result, the solid line width was 27.4 μm. That is, the result is that the target line width (27.3 μm) is much closer than the line width (29.0 μm) predicted in step S2.

  Further, for several kinds of conductive powders, the technology disclosed herein was applied to prepare a photosensitive composition in the same manner as above, and the solid line width was measured. That is, the actual measurement value of the average particle size of the silver powder is obtained in step S1, the expected deviation width is confirmed in step S2, the mixture ratio of the polymerization initiator system is determined in step S3, and the mixture of the vehicle is adjusted. The photosensitive composition was prepared and the solid line width was measured. The results are shown in Table 4. The right end of Table 4 is the result of Example 1 described above. In addition, as a reference example, the solid line width (μm) in the case where the technology disclosed herein is not applied and the base vehicle is used as it is (that is, the mixing ratio of the polymerization initiator system is constant without adjustment) Is described at the bottom.

  FIG. 7 is a graph comparing the results of Table 4 and comparing the solid line widths with and without the application of the technology disclosed herein. As is clear from FIG. 7 and Table 4, by applying the technology disclosed herein, the production lot of the conductive powder is relatively larger than that in the case where the technology disclosed herein is not applied (reference example). The variation in the line width could be suppressed by buffering the variation between the lines. Here, the fluctuation of the line width could be suppressed to ± 1 μm or less, and further to ± 0.5 μm or less. In other words, the fine line-shaped wiring could be stably formed in the vicinity of the target line width. These results demonstrate the significance of the technology disclosed herein.

<Example 2: When two kinds of conductive powders are mixed and used>
Hereinafter, a case of producing a photosensitive composition using a mixed powder obtained by mixing two kinds of conductive powders will be described. Here, as a preliminary preparation, first, two first correlation expressions corresponding to the two conductive powders to be used were prepared. Specifically, the first correlation equation shown by the solid lines in FIGS. 8 and 9 was prepared. In addition, a second correlation formula was also prepared. The same second correlation equation as shown in FIG. 6 was prepared.

  The first correlation equation shown by the solid line in FIG. 8 is prepared as follows. That is, first, as the first conductive powder, a plurality (here, seven types) of first silver powders having an average particle diameter (nominal value) of about 2.9 μm were prepared. Then, as in the case of calculating the first correlation equation of FIG. 5 in Example 1 described above, the average particle diameters (measured values) of the seven types of first silver powders were measured, respectively. As the second conductive powder, a second silver powder having an average particle size (actual measurement value) of 2.56 μm was prepared. Next, the mixed powder was prepared by mixing the first silver powder and the second silver powder in a mass ratio of a predetermined ratio (here, 40:60). A photosensitive composition was prepared by mixing this mixed powder with the vehicle shown in Table 1 in a mass ratio of 77:23. Next, using this photosensitive composition, a wiring pattern was formed in the same manner as in Example 1 described above, and a correlation expression (Y = 1.89X + 24.85) between the average particle diameter (actual measurement value) and the solid line width was calculated. did.

  The first correlation equation shown by the solid line in FIG. 9 is prepared as follows. That is, first, as the second conductive powder, a plurality (here, five types) of second silver powders having an average particle diameter (nominal value) of about 2.4 μm were prepared. Then, the average particle diameters (measured values) of the five types of the second silver powders were measured, respectively, in the same manner as in the calculation of the first correlation equation in FIG. 5 of Example 1 described above. Further, as the first conductive powder, a first silver powder having an average particle size (actual measurement value) of 3.06 μm was prepared. Next, the mixed powder was prepared by mixing the first silver powder and the second silver powder in a mass ratio of 40:60. Then, the correlation equation (Y = 2.12X + 24.72) between the average particle diameter (measured value) and the solid line width was calculated in the same manner as the above-described calculation of the first correlation equation in FIG.

  The first correlation equation shown by the solid line in FIGS. 8 and 9 is similar to the first correlation equation of FIG. 5 of Example 1 in that the average particle diameter (measured value) of the changed silver powder is proportional to the solid line width. (Correlation coefficient: 0.92 or more). The first correlation equation shown by the solid line in FIGS. 8 and 9 is represented by a linear function. In FIGS. 8 and 9, the average particle size (measured value) and the solid line width have a positive correlation.

In Example 2, after aligning the two first correlation equations as described above, in step S1, the first silver powder (average particle size (nominal value): 2.9 μm) and the first silver powder used in the photosensitive composition were prepared. Two kinds of conductive powders of 2 silver powders (average particle diameter (nominal value): 2.4 μm) were prepared. Next, the average particle diameters of the first silver powder and the second silver powder were measured, respectively, as in the calculation of the first correlation equation in FIGS. Next, in step S2, the actually measured value of the first silver powder obtained in step S1 was compared with the first correlation equation (Y = 1.89X + 24.85) in FIG. Moreover, the measured value of the second silver powder was compared with the first correlation expression (Y = 2.12X + 24.72) in FIG. 9. Next, for each of the two types of silver powder, the expected deviation widths α1 and α2 with respect to the target line width (here, set to 30.0 μm) were calculated. That is, assuming that the actually measured values of the first silver powder and the second silver powder are x1 and x2 and the expected line widths are y1 and y2, the expected deviation widths α1 and α2 are obtained from the following equations.
α1 = y1-30.0 = 1.89 × x1 + 24.85-30.0
α2 = y2-30.0 = 2.12 × x2 + 24.72-30.0

Then, the expected deviation width β (μm) when two kinds of conductive powders are mixed and used is obtained from the following equation using the above-mentioned expected deviation widths α1 and α2.
β = α1 + α2

  Next, in step S3, as in Example 1 described above, the compounding ratio of the polymerization initiator system contained in the vehicle was adjusted as shown in Tables 5 and 6. Next, as Step S4, a photosensitive composition was prepared in the same manner as in Example 1 described above. Then, a wiring pattern was formed and the solid line width was measured.

  As is clear from Tables 5 and 6, by applying the technology disclosed herein, even when two kinds of conductive powders are mixed and used, the variation between the manufacturing lots of the conductive powders is buffered. It was possible to suppress variations in line width. Here, the fluctuation of the line width could be suppressed to ± 1 μm or less, and further to ± 0.5 μm or less.

  The first correlation equations shown by broken lines in FIGS. 8 and 9 are for the case where the first silver powder and the second silver powder are mixed at a mass ratio of 70:30, respectively. Even when the mixing ratio is changed in this way, the average particle size (measured value) of the changed silver powder and the solid line width are proportional to each other by a linear function, as in the first correlation equation shown by the solid line. (Correlation coefficient: 0.95 or more). The average particle size (measured value) and the solid line width have a positive correlation. From this, it is considered that the technology disclosed here is applicable to various mixed powders regardless of the mixing ratio.

  The preferred embodiment of the present invention has been described above. However, the above-described embodiment is merely an example, and the present invention can be implemented in various other modes. The present invention can be carried out based on the contents disclosed in this specification and the common general technical knowledge in the field. The technology described in the claims includes various modifications and changes of the above-described embodiments. For example, it is possible to combine some of the above-described embodiments or replace them with other modified modes. In addition, if the technical features are not described as being indispensable, they can be appropriately deleted.

  In the above-described embodiment, the target level factor is defined by the “line width”, but the present invention is not limited to this. The target level factor may be derived from the light absorption or photocurability of the conductive film, and may be, for example, the film thickness of the conductive film, the electrode cross-sectional area, the curing shrinkage ratio, the resistance value, or the like. That is, from FIGS. 1A and 1B, the scattering of light changes due to the difference in the particle size of the conductive powder, and as a result, the light absorption of the conductive film changes, thereby changing the photocurability. I understand that From this point of view, it is apparent to those skilled in the art that not only the line width described above but also the film thickness, the cross-sectional area, the cure shrinkage, and the like can be changed due to the difference in the particle diameter of the conductive powder. Further, it is obvious to those skilled in the art that the resistance value may change accordingly.

For example, the following references 1-3:
-Reference 1: Takashi Ukaji, CMC Technical Library 206, Plastic Surface Treatment Technology and Materials, P. 67, a correlation diagram between the light transmittance (%) of the coating film and the particle diameter (μm);
-Reference 2: Yamamoto Kikinzoku Kinkin Co., Ltd., Polymer Technology Report, Vol. 5 (2011), P. 20, FIG. 15 (relationship between the reaction rate of hexanediol diacrylate and the curing time when the intensity of irradiation light is changed);
-Reference 3: Published by Information Technology Association, UV curing resin compounding design, characteristic evaluation and new application, P.P. 470, FIG. 16 (change in film thickness due to curing shrinkage of UV resist);
It is considered to be supported by the above.

  Considering the description of the above-mentioned documents, it is clear that, for example, in the range of 0.1 to 10 μm, the factors of the light absorption degree and the photocuring degree monotonically increase or decrease in accordance with the change of the particle diameter of the conductive powder. Presumed to be. In other words, it is considered that the fluctuations of the line width due to the displacement of the particle diameter and those displacements are in a proportional or constant function and highly correlated. From the above, it can be said that buffering variations in line width is synonymous with suppressing variations in factors relating to light absorption and photocurability. That is, in the technology disclosed herein, the “target level” may be a target line width, a target film thickness, a target cross-sectional area, a target curing shrinkage ratio, or a target resistance value. Well thought to be. In addition, the “expected shift value” may be a shift width, a shift thickness, a shift cross-sectional area, a shift curing shrinkage ratio, or a shift resistance value, depending on the target level. Conceivable.

  In the above-described embodiment, step S3 is performed after step S2, but the present invention is not limited to this. For example, after step S2, a determination step of comparing the expected deviation width with a preset threshold value may be included. Then, when it is determined in the determination step that the expected deviation width is smaller than the threshold value, step S3 may be omitted and step S4 may be performed.

  In addition, in the above-described embodiment, the correlation equation between the average particle diameter (actual measurement value) and the solid line width is exemplified as the first correlation equation, but the first correlation equation is not limited to this. The variable to be compared with the average particle size (actually measured value) may be, for example, an expected deviation width obtained by subtracting the target line width from the solid line width. That is, the first correlation equation may be represented by a correlation equation between the average particle diameter (actual measurement value) and the expected deviation width. In this case, the actual measurement value obtained in step S1 may be interpolated into the correlation equation to directly confirm the expected deviation width.

  In the above-described embodiment, the correlation equation between the compounding ratio of the organic component in the photosensitive composition and the solid line width is exemplified as the second correlation equation, but the second correlation equation is not limited to this. The variable to be compared with the mixing ratio of the organic components may be, for example, the expected deviation width, as in the case of the first correlation equation. Further, the compounding ratio of the organic component may be represented not by the compounding ratio in the photosensitive composition but by, for example, the compounding ratio in the vehicle.

  In the above-described embodiment, the mixture ratio determination device 30 includes the input unit 31, the storage unit 32, the first calculation unit 33, and the second calculation unit 34, but is not limited to this. In addition to the above-mentioned parts, the compounding ratio determination device 30 has at least one of the following: a first setting part that sets a first correlation equation for a predetermined type of conductive powder and stores it in the storage part 32; Second setting unit for setting the second correlation expression for the conductive powder of the type and storing it in the storage unit 32; the storage unit stores the first correlation expression or the second correlation expression of the same type as the input conductive powder. If not stored in 32, a notification unit for notifying the user of an error; or the like may be provided.

  In Examples 1 and 2 described above, the silver powder was used as the conductive powder, but it is not limited to this. The mechanism that the use of a conductive powder having a large average particle size tends to spread the irradiation light in the horizontal direction of the conductive film in the exposure step and tends to increase the line width of the wiring is the same for other metal species. .. The technique disclosed here is of course applicable not only to silver powder, but also to powders containing the above-mentioned various metals, for example, copper, platinum, palladium, aluminum, nickel and the like.

  In Examples 1 and 2 described above, in step S1, the average particle diameter (D50 particle diameter) of the conductive powder, specifically, corresponds to the integrated value 50% from the smaller particle diameter side in the volume-based particle size distribution. Particle size was measured, but is not limited to this. In step S1, the particle size distribution based on the number may be used instead of the particle size distribution based on the volume. Further, the particle size factor may be, for example, D40 particle size (particle size corresponding to an integrated value of 40% from the smaller particle size distribution side), D60 particle size (particle size) instead of the average particle size (D50 particle size). The particle size corresponding to an integrated value of 60% from the smaller particle size in the distribution) or the like may be used. In this case, the first correlation formula may be represented by "D40 particle size (actual measurement value) X-solid line width Y", "D60 particle size (actual measurement value) X-solid line width Y", or the like. Furthermore, for example, when the particle size distribution of the conductive powder is unimodal, the particle size factor is a particle size further away from the average particle size, for example, D5 particle size (accumulated from the smaller particle size side in the particle size distribution. Value of 5%), D90 particle size (particle size distribution from smaller particle size to 90% integrated value), D95 particle size (particle size distribution from smaller particle to integrated value 90) %) And the like.

  In Examples 1 and 2 described above, in step S3, the second correlation formula relating to the polymerization initiator system was prepared and the blending ratio of the photopolymerization initiator system was adjusted to suppress the line width variation. , But is not limited to this. The organic component for adjusting the blending ratio may be either one of a photopolymerization initiator and a sensitizer, for example.

  In addition, in the above-mentioned Examples 1 and 2, the second correlation equation relating to the polymerization initiator system was prepared in step S3, but instead of this or in addition to this, for example, the second correlation equation relating to the light absorber. By preparing the formula (see FIG. 10) and adjusting the compounding ratio of the light absorber, it is possible to suppress the variation of the line width. In the second correlation formula shown in FIG. 10, the compounding ratio of the ultraviolet absorber in the photosensitive composition and the solid line width are shown by a logarithmic curve. Since the logarithmic curve changes drastically, for example, when the expected deviation width is large, there is an advantage that it is sufficient to slightly change the compounding ratio. Further, for example, by preparing a second correlation formula (see FIG. 11) relating to the polymerization inhibitor and adjusting the compounding ratio of the polymerization inhibitor, it is possible to suppress the line width variation. In the second correlation formula shown in FIG. 11, the compounding ratio of the photopolymerization inhibitor in the photosensitive composition and the solid line width are proportional (correlation coefficient: 0.99). The second correlation equation shown in FIG. 11 is represented by a linear function. The compounding ratio of the polymerization inhibitor and the solid line width have a negative correlation. That is, it can be seen that the line width linearly narrows as the compounding ratio of the polymerization inhibitor system increases. Such a second correlation equation can also be preferably used in the technique disclosed herein, like the second correlation equations of FIGS. 6 and 7 described above.

10 Multilayer Chip Inductor 11 Main Body 12 Ceramic Layer 14 Internal Electrode Layer 20 External Electrode 30 Mixing Ratio Determination Device 31 Input Section 32 Storage Section 33 First Calculation Section 34 Second Calculation Section 35 Display Section

Claims (14)

A method for producing a photosensitive composition containing a conductive powder in a predetermined mixing ratio,
Measuring the particle size of the conductive powder to be used to obtain a measured value;
The measured values, a first correlation equation which is prepared Me pre, and the particle size of the conductive powder, the displacement of the particle size to a factor that fluctuates due to light absorption or light curing conductive film Confirming an expected deviation value of the factor with respect to a predetermined target level by comparing with a first correlation equation with any factor that varies in correlation with
A second correlation equation is prepared Me pre, and factor in the first correlation equation, the variation of the an organic component contained in the photosensitive composition blend ratio of any that correlates the variation of the factor based on the second correlation equation between the organic component, to determine the mixing ratio of the organic components so as to cancel the estimated offset value step;
A method for producing a photosensitive composition, comprising: The organic component is an organic component that adjusts at least one of light absorption and photopolymerizability of the photosensitive composition,
The method for producing the photosensitive composition according to claim 1. The organic component is at least one of a photopolymerization initiator system, a light absorber, and a polymerization inhibitor,
The method for producing the photosensitive composition according to claim 2. The organic component is a photopolymerization initiator system,
The method for producing the photosensitive composition according to claim 3. The factor in the first correlation equation is the line width of the conductive film, the film thickness, the electrode cross-sectional area, the curing shrinkage rate, or the resistance value.
The manufacturing method of the photosensitive composition as described in any one of Claims 1-4. Factor in the first correlation equation, the line width,
A method for producing the photosensitive composition according to claim 1. The second correlation equation is represented by a linear function,
A method for producing the photosensitive composition according to claim 1. The conductive powder contains silver-based particles,
A method for producing the photosensitive composition according to claim 1. The conductive powder includes core-shell particles including a core metal material and a ceramic material that covers at least a part of the surface of the core,
A method for producing the photosensitive composition according to claim 1. The photosensitive composition is used for forming an electrode,
A method for producing the photosensitive composition according to claim 1. The claim 1 photosensitive composition obtained by the production method according to any one of 10 to impart on the substrate, after photocuring and etching, by firing, the photosensitive composition And a step of forming a conductive layer made of the fired body, the method for manufacturing an electronic component. A compounding ratio determination device for determining a compounding ratio of an organic component to a photosensitive composition containing a conductive powder at a predetermined compounding ratio,
An input unit that receives the user's input and inputs the type of the conductive powder to be used and the measured value of the particle size,
A first correlation equation which is prepared Me pre, varies in correlation with the particle size of the conductive powder, the displacement of the particle size to a factor that fluctuates due to light absorption or light curing conductive film A first correlation equation with any of the factors described above, and a second correlation equation prepared in advance , wherein the factor in the first correlation equation and the organic component contained in the photosensitive composition A storage unit for storing a second correlation expression with any organic component in which the fluctuation of the correlation with the fluctuation of the factor ,
A first calculation unit that calculates an expected deviation value of a factor in the first correlation formula with respect to a predetermined target level from the actual measurement value input to the input unit based on the first correlation formula ;
A second calculation unit that calculates the blending ratio of the organic components in the second correlation equation that cancels the predicted deviation value based on the second correlation equation ;
A compounding ratio determination device including: The factor in the first correlation equation is the line width of the conductive film, the film thickness, the electrode cross-sectional area, the curing shrinkage rate, or the resistance value.
The blending ratio determination device according to claim 12. A computer program configured to operate a computer as the blending ratio determination device according to claim 12 or 13 .

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