Method for manufacturing photosensitive paste and electronic components

Abstract

This photosensitive paste contains: an inorganic powder that contains an element which becomes a polyvalent metal ion; an alkali-soluble polymer; a photosensitive monomer; and a photopolymerization initiator. When the inorganic powder containing an element that becomes a polyvalent metal ion is dispersed at 1 wt% in purified water, the resulting dispersion has an electroconductivity of no more than 170 mS / m when 10 minutes have passed after the dispersion.

Description

Technical Field

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

Background Art

[0002] A method using a photosensitive paste containing an inorganic component and an organic component is known for forming an insulating layer or a wiring conductor of an electronic component or a printed wiring board.

[0003] For example, Patent Document 1 discloses a photosensitive glass paste including an inorganic component containing glass powder and a ceramic filler, and an organic component having photosensitivity. As the organic component having photosensitivity, an alkali-soluble polymer, a photosensitive monomer, a photopolymerization initiator, a solvent, etc. are contained, and as the alkali-soluble polymer, a polymer having a carboxy group in a side chain such as a copolymer of methacrylic acid - methyl methacrylate is mentioned.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] The glass powder used in the photosensitive glass paste described in Patent Document 1 contains alkaline earth metal elements and lanthanides. When such glass powder is kneaded with a polymer having acidic functional groups such as carboxyl groups to form a paste, polyvalent metal ions such as alkaline earth metal elements present on the surface of the glass powder, and polyvalent metal ions such as alkaline earth metal elements eluted from the glass powder into the paste, are adsorbed onto the acidic functional groups of the polymer and crosslinked. As a result of this crosslinking between the inorganic glass powder and the polymer, there is a problem in that the paste becomes thicker (gelled).

[0006] As a measure to prevent the adsorption of polyvalent metal ions and acidic functional groups of polymers, Patent Document 2 discloses a conductive paste containing copper particles and a photosensitive organic component, as well as a polycarboxylic acid and a chelating agent. According to Patent Document 2, low molecular weight organic acids such as polycarboxylic acid and chelating agents adsorb to and cover the surface of the inorganic powder copper particles, thereby preventing the adsorption of copper particles and polymers and preventing the conductive paste from becoming thicker. However, since the low molecular weight organic acids added are substances that dissolve in the paste solution, it is not possible to prevent the elution of copper ions into the paste.

[0007] In the case of photolithography pastes, if alkaline earth metal elements or polyvalent metal ions such as copper dissolve into the paste, the acidic functional groups of the polymer already form salts with the polyvalent metal ions at the paste stage, thus reducing the solubility of the polymer in alkaline developer. Furthermore, the polyvalent metal ions dissolved in the paste undergo dark reactions with polymerizable monomers and oligomers, causing thickening (gelation). In the conductive paste described in Patent Document 2, it is not possible to prevent insolubilization in alkaline developer and dark reactions with polymerizable monomers, making it impossible to achieve both gelation prevention and photolithographic properties.

[0008] The present invention has been made to solve the above problems and aims to provide a photosensitive paste in which thickening and insolubilization in alkaline developer caused by polyvalent metal ions are prevented. The present invention also aims to provide a method for manufacturing an electronic component comprising the step of forming an insulating layer using the photosensitive paste. The present invention also aims to provide a method for manufacturing an electronic component comprising the step of forming a conductive layer using the photosensitive paste. [Means for solving the problem]

[0009] The photosensitive paste of the present invention contains an inorganic powder containing an element that becomes a polyvalent metal ion, an alkali-soluble polymer, a photosensitive monomer, and a photopolymerization initiator, and is characterized in that the conductivity of a dispersion obtained by dispersing the inorganic powder containing the element that becomes a polyvalent metal ion at a concentration of 1% by weight in pure water is 170 mS / m or less 10 minutes after dispersion.

[0010] The present invention provides a method for manufacturing an electronic component, comprising the steps of forming an insulating layer using an insulating paste and forming a conductive layer on the insulating layer using a conductive paste.

[0011] The first method for manufacturing an electronic component of the present invention is characterized in that the insulating paste is the photosensitive paste of the present invention.

[0012] The second method for manufacturing an electronic component of the present invention is characterized in that the conductive paste is the photosensitive paste of the present invention. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a photosensitive paste in which thickening and insolubilization in alkaline developing solutions caused by polyvalent metal ions are prevented. [Brief explanation of the drawing]

[0014] [Figure 1] Figure 1 is a graph showing the conductivity of a dispersion of inorganic powder in pure water at a concentration of 1% by weight. [Figure 2]Figure 2 is a graph showing the Brookfield viscosity measurement results for the photosensitive pastes prepared in the examples. [Figure 3A] Figure 3A is a photograph showing the planar shapes of various patterns formed by photolithography using a photosensitive paste containing glass frit coated with 3% by weight of tetraethoxysilane. [Figure 3B] Figure 3B is a photograph showing the cross-sectional shape of the pattern in Figure 3A. [Figure 4] Figure 4 is a photograph showing the planar shapes of various patterns formed by photolithography using a photosensitive paste containing glass frit coated with 3% by weight of tetraethoxysilane and polyvinylpyrrolidone. [Figure 5] Figure 5 is a photograph showing the planar shapes of various patterns formed by photolithography using a photosensitive paste containing glass frit coated with 6% by weight of tetraethoxysilane and polyvinylpyrrolidone. [Figure 6A] Figure 6A is a photograph showing the planar shapes of various patterns formed by photolithography using a photosensitive paste containing glass frit coated with malonic acid. [Figure 6B] Figure 6B is a photograph showing the cross-sectional shape of the pattern in Figure 6A. [Modes for carrying out the invention]

[0015] The photosensitive paste of the present invention, the method for manufacturing the first electronic component of the present invention, and the method for manufacturing the second electronic component of the present invention will be described below. However, the present invention is not limited to the following configurations and may be modified as appropriate without departing from the spirit of the invention. Furthermore, a combination of several of the preferred configurations described below also constitutes the present invention.

[0016] <Photosensitive paste> The photosensitive paste of the present invention contains an inorganic powder containing an element that becomes a polyvalent metal ion, an alkali-soluble polymer, a photosensitive monomer, and a photopolymerization initiator. The photosensitive paste of the present invention includes a photosensitive insulating paste used for forming an insulating layer or a photosensitive conductor paste used for forming a conductor layer. First, the case where the photosensitive paste of the present invention is a photosensitive insulating paste will be described.

[0017] [Photosensitive Insulating Paste] (Inorganic powder containing an element that becomes a polyvalent metal ion) In the inorganic powder containing an element that becomes a polyvalent metal ion, the "element that becomes a polyvalent metal ion" is not particularly limited as long as it is an element that becomes a divalent or higher metal ion. For example, alkaline earth metals, metal elements of Group 3 to Group 14, etc. can be mentioned. In the present invention, the element that becomes a polyvalent metal ion is preferably at least one element selected from the group consisting of alkaline earth metals, lanthanoids, Ni, Cu, Pd, Al, Ti, Zr, Zn, Ga, Pb, Nb, Fe, Co, and V.

[0018] In the photosensitive insulating paste of the present invention, the inorganic powder containing an element that becomes a polyvalent metal ion is preferably an insulator mainly composed of a metal oxide crystal or an amorphous insulator mainly composed of SiO2. By firing a photosensitive paste containing an insulator mainly composed of a metal oxide crystal or an amorphous insulator mainly composed of SiO2, an insulator material with high strength can be obtained.

[0019] Examples of the insulator mainly composed of a metal oxide crystal include TiO2, BaTiO, NiO, etc. Examples of the amorphous insulator mainly composed of SiO2 include SiO2 - B2O3 - Na2O - K2O - CaO - Al2O3 - based glass powder, SiO2 - B2O3 - Na2O - K2O - Al2O3 - based glass powder, etc.

[0020] In the photosensitive insulating paste of the present invention, the inorganic powder containing an element that becomes a polyvalent metal ion is preferably glass powder having a crystallization point. This is because by firing a photosensitive paste containing glass powder having a crystallization point, an insulator material with even higher strength can be obtained. Examples of glass powders having crystallization points include glass powders containing B2O3, CaO, ZnO, Bi2O3, BaO, MgO, La2O3, Na2O, K2O and / or Al2O3 in addition to SiO2, such as SiO2-B2O3-Al2O3-CaO glass powder, SiO2-B2O3-BaO-ZnO-Al2O3-MgO-La2O3 glass powder, and SiO2-B2O3-CaO-Al2O3-Na2O-K2O glass powder.

[0021] The glass powder having the above crystallization point is preferably one whose softening point (Ts) and crystallization point (Tc) are adjusted according to the firing conditions. For example, when firing is performed at 850°C to 950°C, it is preferable to use glass powder with a Ts of 800°C and a Tc of 890°C. The composition of the glass powder having the above crystallization point is not limited to the above examples, as long as the glass powder has equivalent Ts and Tc.

[0022] These inorganic powders containing elements that form polyvalent metal ions may be used individually or in combination of two or more types.

[0023] The photosensitive insulating paste of the present invention is characterized in that the conductivity of a dispersion of an inorganic powder containing the above-mentioned polyvalent metal ion element dispersed in pure water at a concentration of 1% by weight is 170 mS / m or less 10 minutes after dispersion. The thickening and deterioration of alkali solubility of the photosensitive insulating paste occur due to crosslinking between acidic functional groups such as carboxyl groups of the alkali-soluble polymer and polyvalent metal ions on the surface of the inorganic powder or polyvalent metal ions eluted from the inorganic powder into the paste. Therefore, the more polyvalent metal ions there are on the surface of the inorganic powder, or the easier it is for polyvalent metal ions to elute from the inorganic powder, the more likely the photosensitive insulating paste is to thicken and deteriorate in alkali solubility. The ease with which polyvalent metal ions elute can be investigated by measuring the conductivity when the target inorganic powder is dispersed in pure water. The photosensitive insulating paste of the present invention can suppress the thickening and insolubilization of the photosensitive insulating paste in alkaline developer caused by polyvalent metal ions by using an inorganic powder having an conductivity of 170 mS / m or less. The conductivity is preferably 100 mS / m or less, more preferably 50 mS / m or less. On the other hand, the conductivity is, for example, 0 mS / m or more.

[0024] In the photosensitive insulating paste of the present invention, it is preferable that the content of the element that becomes a polyvalent metal ion on the surface of the inorganic powder containing the element that becomes a polyvalent metal ion is less than 2.0 atomic percent. When the content of the element that becomes a polyvalent metal ion on the surface of the inorganic powder is less than 2.0 atomic percent, the adsorption of the polyvalent metal ions on the surface of the inorganic powder to the alkali-soluble polymer is suppressed, and the viscosity of the photosensitive insulating paste can be prevented from increasing. More preferably, the content of the element that becomes a polyvalent metal ion is less than 1.0 atomic percent. On the other hand, the content of the element that becomes a polyvalent metal ion may be 0 atomic percent. In this specification, the content of the element that becomes a polyvalent metal ion on the surface of the inorganic powder is a value obtained qualitatively and quantitatively by X-ray photoelectron spectroscopy (XPS).

[0025] In the photosensitive insulating paste of the present invention, it is preferable that at least a portion of the surface of the inorganic powder containing the element that becomes the polyvalent metal ion is covered with a ceramic coating. By covering at least a portion of the surface of the inorganic powder with a ceramic coating that has high chemical stability, it is possible to suppress the adsorption of alkali-soluble polymers onto the inorganic powder and the elution of polyvalent metal ions from the inorganic powder. It is more preferable that the entire surface of the inorganic powder is covered with a ceramic coating.

[0026] The main component of the above ceramic coating is preferably SiO2. This is because SiO2 has high chemical stability and can prevent alkali-soluble polymers from adsorbing onto the inorganic powder and prevent polyvalent metal ions from leaching out from the inorganic powder. The ceramic coating described above may contain elements that become polyvalent metal ions in addition to SiO2, but it is preferable that their concentration be lower than that inside the inorganic powder. The main component of the ceramic coating, SiO2, is preferably 95% by mass or more, more preferably 98% by mass or more, and even more preferably 99% by mass or more.

[0027] The ratio of the ceramic coating to the inorganic powder is preferably 2.5% to 6.5% by weight per 100% by weight of inorganic powder, calculated on an SiO2 basis. If the ratio of the ceramic coating is less than 2.5% by weight, the effect of preventing the adsorption of alkali-soluble polymers to the inorganic powder and the elution of polyvalent metal ions may not be sufficient. If it exceeds 6.5% by weight, the effect of preventing the adsorption of alkali-soluble polymers to the inorganic powder and the elution of polyvalent metal ions does not improve further, which is economically undesirable.

[0028] The ceramic coating may be a film containing inorganic components such as SiO2 and organic materials, or it may be an organic-inorganic hybrid film. In particular, if the ceramic coating is an organic-inorganic hybrid film, the flexibility of the ceramic coating is improved and cracks can be prevented from occurring in the ceramic coating. As the organic material, poly(2-methyloxazoline), poly(N,N-dimethylacrylamide), polyvinylpyrrolidone (PVP), etc., which have an amide-carbonyl group can be used. The proportion of organic material in the ceramic coating is preferably 0.01% by weight or more and 1.0% by weight or less per 100% by weight of inorganic powder, in terms of SiO2.

[0029] In the photosensitive insulating paste of the present invention, it is preferable that the difference between the refractive index N1 of the ceramic coating and the refractive index N2 of the mixture of the alkali-soluble polymer, the photosensitive monomer, and the photopolymerization initiator is |N1-N2| ≤ 0.3. If the refractive index difference between the ceramic coating and the mixture of the alkali-soluble polymer, the photosensitive monomer, and the photopolymerization initiator is large, the irradiated light is more likely to scatter, which can lead to thicker lines in the pattern and deterioration of deep curing performance. When the refractive index difference is within the above range, the scattering of irradiated light can be reduced and the resolution can be improved. More preferably, |N1-N2| ≤ 0.1. On the other hand, |N1-N2| = 0 is also acceptable.

[0030] Various methods can be used to cover the surface of inorganic powder with a ceramic coating, including coating the surface of the inorganic powder with a separately prepared ceramic material, oxidizing the inorganic powder to create an oxide film on its surface, and applying a solution that forms an oxide through heat treatment to the surface of the inorganic powder, followed by heat treatment under predetermined conditions to coat the surface of the inorganic powder with ceramics (e.g., the sol-gel method). The sol-gel method is preferred because it facilitates the formation of an organic-inorganic hybrid film.

[0031] The photosensitive insulating paste of the present invention preferably contains a filler (aggregate) in addition to the insulator mainly composed of metal oxide crystals and the amorphous insulator mainly composed of SiO2. In this specification, "filler" refers to inorganic particles that do not soften and exist as particles even in the firing temperature range of the photosensitive paste (e.g., 850°C to 950°C). Various ceramic materials can be used as the filler, and examples of crystalline fillers include quartz, alumina, magnesia, spinel, silica, forsteride, steatite, and zirconia. The filler may be used individually or in combination of two or more types. By using the filler, the thermal expansion coefficient of the insulating layer can be reduced, thereby avoiding formation defects and fracture during firing. As fillers, alumina and quartz are preferred. Alumina has a refractive index close to that of alkali-soluble polymers, and using alumina allows the insulating layer to obtain good strength while also having excellent resolution. Quartz has a low refractive index, which is close to that of alkali-soluble polymers, so sinterability can be controlled while maintaining resolution. The degree of crystallinity of the quartz is not particularly limited.

[0032] In the photosensitive insulating paste of the present invention, the particle size of the inorganic powder containing the element that becomes the polyvalent metal ion and the filler is preferably 0.1 μm or more and 5.0 μm or less. If the particle size is smaller than 0.1 μm, dispersion in the paste may be difficult, and if the particle size is larger than 5.0 μm, the smoothness of the insulating layer and the groove shape formed after development may be irregular. More preferably, the particle size is 0.3 μm or more and 3.0 μm or less. The particle sizes of the inorganic powder and filler are values ​​measured using a laser diffraction particle size distribution analyzer (LA960) manufactured by Horiba, Ltd.

[0033] In the photosensitive insulating paste of the present invention, the total content of the inorganic powder containing the element that becomes the polyvalent metal ion and the filler is preferably 50% by weight or more and 80% by weight or less, and more preferably 60% by weight or more and 70% by weight or less. The preferred ratio of the inorganic powder containing the element that becomes the polyvalent metal ion to the filler is 40% to 60% by weight of the inorganic powder, when the total of the inorganic powder and filler is considered to be 100% by weight.

[0034] (Alkali-soluble polymer) As alkali-soluble polymers, for example, polymers such as acrylic copolymers having functional groups such as carboxyl groups in their side chains can be used. Specifically, examples include copolymers of unsaturated carboxylic acids and ethylenically unsaturated compounds other than unsaturated carboxylic acids. Examples of unsaturated carboxylic acids include acrylic acid, methacrylic acid, maleic acid, fumaric acid, vinyl acetic acid, and their acid anhydrides. Examples of ethylenically unsaturated compounds other than unsaturated carboxylic acids include unsaturated carboxylic acid esters. Specifically, examples include acrylic acid esters such as methyl acrylate and ethyl acrylate, methacrylic acid esters such as methyl methacrylate and ethyl methacrylate, and fumaric acid esters such as monoethyl fumarate. Furthermore, as an acrylic copolymer having a carboxyl group in the side chain, one in which an unsaturated bond of the following form may be introduced may be used. (1) An acrylic monomer having a functional group such as an epoxy group that can react with the carboxyl group of the side chain of the acrylic copolymer is added. (2) The acrylic copolymer, in which epoxy groups are introduced in place of carboxyl groups in the side chains, is reacted with an unsaturated monocarboxylic acid, and then a saturated or unsaturated polycarboxylic acid anhydride is introduced. Furthermore, as an acrylic copolymer having carboxyl groups in its side chains, it is preferable that the weight-average molecular weight (Mw) is 50,000 or less, and the acid value is 30 mg KOH / g or more and 150 mg KOH / g or less.

[0035] There are no particular restrictions on the photosensitive monomer and photopolymerization initiator; known ones used in photosensitive pastes can be used.

[0036] The content of the alkali-soluble polymer, photosensitive monomer, and photopolymerization initiator in the photosensitive insulating paste of the present invention is preferably 25% by weight or more, more preferably 30% by weight or more, and also preferably 45% by weight or less, more preferably 35% by weight or less.

[0037] The photosensitive insulating paste of the present invention may further contain an organic solvent, an organic dye, etc. Known organic solvents and dyes used in photosensitive pastes can be used.

[0038] [Photosensitive conductive paste] Next, we will describe the case where the photosensitive paste of the present invention is a photosensitive conductive paste, but below we will mainly describe the differences from the photosensitive insulating paste described above.

[0039] The "elements that become polyvalent metal ions" in the photosensitive conductive paste of the present invention are the same as those exemplified for the photosensitive insulating paste described above.

[0040] In the photosensitive conductive paste of the present invention, the inorganic powder containing the element that becomes the polyvalent metal ion is preferably a metal. As the metal used in the photosensitive conductive paste of the present invention, base metals, which have conventionally caused problems with thickening in photosensitive pastes, are preferred. The metal is preferably an element that becomes the polyvalent metal ion, and more preferably at least one element selected from the group consisting of alkaline earth metals, lanthanides, Ni, Cu, Pd, Al, Ti, Zr, Zn, Ga, Pb, Nb, Fe, Co, and V. The metal is even more preferably Cu or Ni.

[0041] In the photosensitive conductive paste of the present invention, the content of the element that becomes a polyvalent metal ion in the inorganic powder containing the element that becomes a polyvalent metal ion is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and may be 100% by mass.

[0042] In the photosensitive conductive paste of the present invention, if the inorganic powder containing the element that becomes the polyvalent metal ion is a metal, one type of inorganic powder may contain two or more metals, or two or more inorganic powders each containing one different metal may be included. When two or more inorganic powders each containing one different metal are included, when the photosensitive conductive paste is fired, the different metals react with each other to form an alloy. In the photosensitive conductive paste of the present invention, when two or more metals are used, it is preferable to use two or more inorganic powders each containing one different metal.

[0043] The photosensitive conductive paste of the present invention may contain a bonding agent in addition to the inorganic powder containing the elements that become polyvalent metal ions. Examples of the bonding agent include, but are not limited to, SiO2-B2O3-Bi2O3 glass powder. In the photosensitive conductive paste of the present invention, the total content of inorganic powder containing the element that becomes the polyvalent metal ion is preferably 60% by weight or more and 85% by weight or less, and more preferably 65% ​​by weight or more and 80% by weight or less.

[0044] In the photosensitive conductive paste of the present invention, the particle size of the inorganic powder containing the element that becomes the polyvalent metal ion and the bonding agent is preferably 0.1 μm or more and 5.0 μm or less. The particle size of the inorganic powder and bonding agent can be measured by the method described above for the photosensitive insulating paste.

[0045] In the photosensitive conductive paste of the present invention, the conductivity of the inorganic powder containing the element that becomes a polyvalent metal ion, and the content of the element that becomes a polyvalent metal ion on the surface of the inorganic powder containing the element that becomes a polyvalent metal ion, are the same as the values ​​in the photosensitive insulating paste described above. In the photosensitive conductive paste of the present invention, it is preferable that at least a portion of the surface of the inorganic powder containing the element that becomes the polyvalent metal ion is covered with a ceramic coating, and the form and composition of the ceramic coating are the same as those of the photosensitive insulating paste described above.

[0046] The types and forms of the alkali-soluble polymer, photosensitive monomer, photopolymerization initiator, organic solvent, and organic dye contained in the photosensitive conductive paste of the present invention are the same as those of the photosensitive insulating paste described above. The content of the alkali-soluble polymer, photosensitive monomer, and photopolymerization initiator in the photosensitive conductive paste of the present invention is preferably 10% by weight or more, more preferably 15% by weight or more, and also preferably 35% by weight or less, more preferably 20% by weight or less.

[0047] [Manufacturing methods for electronic components] The present invention includes a method for manufacturing an electronic component, or a method for manufacturing a second electronic component. The first method for manufacturing an electronic component of the present invention comprises the steps of forming an insulating layer using an insulating paste and forming a conductive layer on the insulating layer using a conductive paste, wherein the insulating paste is the photosensitive insulating paste of the present invention.

[0048] The following describes an example of a method for manufacturing the first electronic component of the present invention. First, the photosensitive insulating paste of the present invention is repeatedly applied by screen printing to form an insulating paste layer of a desired thickness. This insulating paste layer is an outer insulating layer located outside the conductor layer.

[0049] Grooves for the internal electrode pattern are formed in the insulating paste layer created above using a photolithography method.

[0050] Next, a conductive paste layer is formed by filling and coating a conductive paste onto an insulating paste layer having grooves for an internal electrode pattern, and the conductive layer is patterned to the desired pattern using a photolithography method. This forms a conductive paste layer that will become the internal electrode on the insulating paste layer. At this time, a desired coil pattern can be drawn on a photomask. Furthermore, the conductive paste used in the first method of manufacturing an electronic component of the present invention is not particularly limited, and for example, known Ag paste can be used, but the photosensitive conductive paste of the present invention may also be used.

[0051] Next, the photosensitive insulating paste of the present invention is applied onto the conductive paste layer to form an insulating paste layer that will become the internal insulating layer. After removing unnecessary parts using a photolithography method, the conductive paste is filled and applied to form a conductive paste layer.

[0052] By repeating the above process the required number of times, a paste laminate is formed consisting of an outer insulating layer, an insulating paste layer that serves as the inner insulating layer, and a conductive paste layer. Finally, the insulating paste is repeatedly applied to the paste laminate by screen printing to form an insulating paste layer. This insulating paste layer is an outer insulating layer located outside the conductor layer. The mother laminate is obtained through the above process.

[0053] The obtained mother laminate is cut into multiple unfired laminates by dicing or other methods. The cut unfired laminates are fired at a temperature between 850°C and 950°C to obtain laminates. The obtained laminates are subjected to barrel finishing or plating as needed. The electronic component is completed through the above process.

[0054] The second method for manufacturing an electronic component of the present invention comprises the steps of forming an insulating layer using an insulating paste and forming a conductive layer on the insulating layer using a conductive paste, wherein the conductive paste is the photosensitive conductive paste of the present invention.

[0055] The method for manufacturing the second electronic component of the present invention can be carried out in the same manner as the method described above as an example of the method for manufacturing the first electronic component. In the method for manufacturing the second electronic component, known insulating pastes can be used, such as known photosensitive glass pastes. The conductor layer is formed using the photosensitive conductor paste of the present invention. [Examples]

[0056] The following are examples that more specifically disclose the present invention. However, the present invention is not limited to these examples.

[0057] [Photosensitive paste] (Solu-gel coating of inorganic powder) As a glass powder containing elements that form polyvalent metal ions and having a crystallization point, glass frit with SiO2-B2O3-Al2O3-CaO as the main component, with an average particle size of 1.0 μm, a softening point (Ts) of 800°C, and a crystallization point (Tc) of 890°C was used. 20 g of this glass frit was added to 37.2 g of ethanol. Next, tetraethoxysilane (TEOS) was weighed to 3% by weight or 6% by weight per 100% by weight of glass frit, based on SiO2, and added to the ethanol containing the glass frit and stirred to prepare samples with different TEOS concentrations. Furthermore, 0.1% by weight of polyvinylpyrrolidone (PVP) per 100% by weight of glass frit was weighed, dissolved in 3.2 g of pure water, and dropped into the ethanol containing the glass frit and 3% by weight of TEOS, or the ethanol containing the glass frit and 6% by weight of TEOS, and stirred for 60 minutes. As a result, glass frit coated with TEOS or TEOS and PVP was obtained, forming a ceramic coating. As a comparative example, malonic acid was added instead of TEOS and PVP to obtain glass frit with a malonic acid coating on the surface.

[0058] (Preparation of photosensitive paste) A photosensitive paste was prepared by blending each material in the following proportions. Specifically, each material was weighed, the weighed material was stirred in a planetary mixer for 30 minutes, and then kneaded by passing it through a three-roll mill four times to produce the photosensitive paste. As a comparative example, a photosensitive paste was also prepared using uncoated glass frit instead of coated glass frit. <Organic ingredients> Alkali-soluble polymer: 24.7 parts by weight of copolymer of methacrylate and methyl methacrylate Photosensitive monomer: Trimethylolpropane triacrylate 8.2 parts by weight Solvent: Pentamethylene glycol 2.6 parts by weight Photopolymerization initiator (1): 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one 0.4 parts by weight Photopolymerization initiator (2): 0.2 parts by weight of 2,4-diethylthioxanthone Photopolymerization initiator (3): Bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide 0.7 parts by weight Yellow dye: Oil Yellow 129 (product name, manufactured by Orient Chemical Industry Co., Ltd.) 0.2 parts by weight <Inorganic components> Inorganic powder mixture total 63 parts by weight The inorganic powder mixture described above was prepared by blending the glass frit, alumina, and quartz coated as described above in a volume ratio of 50:20:30. The refractive index of the mixture of alkali-soluble polymer, photosensitive monomer, and photopolymerization initiator (1) to (3) was approximately 1.5, and the refractive index of the ceramic coating containing 3% by weight of TEOS was 1.55. The refractive index of the ceramic coating containing 3% by weight of TEOS and PVP, and the refractive index of the ceramic coating containing 6% by weight of TEOS and PVP, were between 1.50 and 1.80, respectively.

[0059] [Evaluation of inorganic powders] (Measurement and evaluation of electrical conductivity) 1 g of glass frit coated with TEOS, or 1 g of glass frit coated with TEOS and PVP, was added to 100 g of pure water, and then stirred with a spatula for approximately 60 seconds to prepare a 1 wt% glass frit dispersion. The conductivity of the dispersion was measured using a conductivity meter (Horiba D-54, 355-10D). Conductivity measurements were taken at 1-minute intervals from the time of glass frit addition until 5 minutes had elapsed, and then at 8 minutes and 10 minutes after that. Conductivity measurements were also taken for uncoated glass frit and glass frit coated with malonic acid in the same manner. The results are shown in Figure 1.

[0060] Figure 1 is a graph showing the conductivity of dispersions obtained by dispersing inorganic powder in pure water at a concentration of 1% by weight. As shown in Figure 1, glass frit coated with TEOS and glass frit coated with TEOS and PVP had low conductivity from immediately after dispersion to 10 minutes later, below 170 mS / m. Glass frit that was not coated (uncoated) and glass frit coated with malonic acid (malonic acid coated) had high conductivity of above 1200 mS / m from immediately after dispersion to 10 minutes later. Among the coated glass frits, glass frit coated with TEOS alone had the lowest conductivity.

[0061] (Measurement of elemental composition on the surface of inorganic powder) The elemental composition of the glass frit surface before and after coating was measured and analyzed using XPS (X-ray photoelectron spectroscopy). The results are shown in Table 1. Equipment: ULVAC-PHI VersaProbe Measurement area: 100μmφ Analysis depth: several nm

[0062] [Table 1]

[0063] The values ​​in Table 1 are not absolute values; they were calculated so that the sum of all compositions equals 100 atomic percent. In Table 1, "-" indicates that the value is below the detection limit. Note that Table 1 omits the listing of trace atoms, so the total may not always equal 100 atomic percent.

[0064] As shown in Table 1, the surface of untreated glass frit (uncoated) had a Ca content of 9 atomic percent, which is an element that forms polyvalent metal ions, while the Ca content of treated glass frit was less than 1 atomic percent.

[0065] [Evaluation of photosensitive paste] (viscosity measurement) The viscosity of the photosensitive paste was measured using a Brookfield viscometer (BF viscometer) at a rotation speed of 100 rpm and a temperature of 25°C. Measurements were taken immediately after preparation of the photosensitive paste (day 0), on day 3, day 10, and day 38. The results are shown in Figure 2.

[0066] Figure 2 is a graph showing the measurement results of the BF viscosity of the photosensitive pastes prepared in the examples. As shown in Figure 2, the viscosity of the photosensitive paste containing coated glass frit gradually increased from the time of preparation until 10 days later, but there was almost no further increase in viscosity thereafter, and it could be used for screen printing and other applications even 38 days after preparation. On the other hand, the photosensitive paste containing uncoated glass frit gelled immediately after mixing with organic components, and its viscosity could not be measured. Among the photosensitive pastes containing coated glass frit, the viscosity of the photosensitive paste containing glass frit coated with 3% by weight of TEOS and the photosensitive paste containing glass frit coated with 3% by weight of TEOS and PVP was relatively low.

[0067] (Developability) A photosensitive paste containing coated glass frit was screen printed to a thickness of 20 μm, dried in a safety oven, exposed to light through a photomask with openings of various sizes, and developed with an alkaline aqueous solution to form a pattern. A similar pattern was formed using a photosensitive paste containing glass frit coated with malonic acid. The results are shown in Figures 3A, 3B, 4, 5, 6A, and 6B.

[0068] Figure 3A is a photograph showing the planar shapes of various patterns formed by photolithography using a photosensitive paste containing glass frit coated with 3% by weight of TEOS. Figure 3B is a photograph showing the cross-sectional shape of the pattern in Figure 3A.

[0069] Figure 4 is a photograph showing the planar shapes of various patterns formed by photolithography using a photosensitive paste containing glass frit coated with 3 wt% TEOS and PVP.

[0070] Figure 5 is a photograph showing the planar shapes of various patterns formed by photolithography using a photosensitive paste containing glass frit coated with 6% by weight of TEOS and PVP.

[0071] Figure 6A is a photograph showing the planar shape of various patterns formed by photolithography using a photosensitive paste containing glass frit coated with malonic acid. Figure 6B is a photograph showing the cross-sectional shape of the pattern in Figure 6A.

[0072] As shown in Figures 3A, 3B, 4, and 5, the photosensitive paste containing glass frit coated with TEOS or TEOS and PVP dissolved in the alkaline aqueous solution and grooves were formed. However, as shown in Figures 6A and 6B, the photosensitive paste containing glass frit with a surface coated with malonic acid did not dissolve in the alkaline aqueous solution in the unexposed areas, instead swelling and no grooves were formed.

Claims

1. It contains an inorganic powder containing elements that become polyvalent metal ions, an alkali-soluble polymer, a photosensitive monomer, and a photopolymerization initiator. At least a portion of the surface of the inorganic powder containing the element that becomes the polyvalent metal ion is covered with a ceramic coating. 95% or more by mass of the ceramic coating is SiO₂, A photosensitive paste characterized in that the conductivity of a dispersion liquid obtained by dispersing an inorganic powder containing the element that becomes a polyvalent metal ion in pure water at a concentration of 1% by weight is 170 mS / m or less 10 minutes after dispersion.

2. The photosensitive paste according to claim 1, wherein the content of the element that becomes a polyvalent metal ion on the surface of the inorganic powder containing the element that becomes a polyvalent metal ion is less than 2.0 atomic percent.

3. The photosensitive paste according to claim 1, wherein the difference between the refractive index N1 of the ceramic coating and the refractive index N2 of the mixture of the alkali-soluble polymer, the photosensitive monomer, and the photopolymerization initiator is |N1-N2| ≤ 0.

3.

4. The inorganic powder containing the element that becomes the polyvalent metal ion is an insulator mainly composed of metal oxide crystals or SiO ２ The photosensitive paste according to claim 1, wherein the photosensitive paste is an amorphous insulator mainly composed of [the specified substance].

5. The photosensitive paste according to claim 4, wherein the element that forms the polyvalent metal ion is at least one element selected from the group consisting of alkaline earth metals, lanthanides, Ni, Cu, Pd, Al, Ti, Zr, Zn, Ga, Pb, Nb, Fe, Co, and V.

6. The photosensitive paste according to claim 1, wherein the inorganic powder containing the element that becomes a polyvalent metal ion is an amorphous insulator mainly composed of SiO2.

7. The photosensitive paste according to claim 6, wherein the amorphous insulator mainly composed of SiO2 comprises SiO2-B2O3-Na2O-K2O-CaO-Al2O3-based glass powder, or SiO2-B2O3-Na2O-K2O-Al2O3-based glass powder.

8. The photosensitive paste according to claim 1, wherein the inorganic powder containing the element that becomes a polyvalent metal ion is a glass powder having a crystallization point.

9. The photosensitive paste according to claim 8, wherein the glass powder having a crystallization point comprises SiO₂-B₂O₃-Al₂O₃-CaO-based glass powder, SiO₂-B₂O₃-BaO-ZnO-Al₂O₃-MgO-La₂O₃-based glass powder, or SiO₂-B₂O₃-CaO-Al₂O₃-Na₂O-K₂O-based glass powder.

10. The photosensitive paste according to claim 1, wherein the inorganic powder containing the element that becomes a polyvalent metal ion is a glass powder mainly composed of SiO₂-B₂O₃-Al₂O₃-CaO.

11. The photosensitive paste according to claim 1, wherein the ceramic coating is a film containing SiO2 and an organic substance.

12. The photosensitive paste according to claim 11, wherein the organic substance is poly(2-methyloxazoline), poly(N,N-dimethylacrylamide), or polyvinylpyrrolidone having an amide carbonyl group.

13. The photosensitive paste according to claim 11, wherein the organic substance is polyvinylpyrrolidone.

14. The photosensitive paste according to claim 1, wherein the particle size of the inorganic powder containing the element that becomes a polyvalent metal ion is 0.1 μm or more and 5.0 μm or less.

15. A process of forming an insulating layer using insulating paste, The process includes the step of forming a conductive layer on the insulating layer using a conductive paste, A method for manufacturing an electronic component, characterized in that the insulating paste is the photosensitive paste described in any one of claims 1 to 14.

Images