JP2007086268A - Photosensitive sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photosensitive sheet which ensures pattern processability with a high aspect ratio without requiring a complicated step nor requiring a special exposing device. <P>SOLUTION: The photosensitive sheet contains a photosensitive organic component and inorganic particles and can be worked to a pattern by photolithography, wherein the photosensitive sheet satisfies Tb>Ta between light transmission Ta of a part of the sheet up to 10% of the total thickness from a light receiving surface and light transmission Tb of a part of the sheet up to 10% of the total thickness from a surface opposite to the light receiving surface, with respect to the light of a wavelength region of 320-780 nm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a photosensitive sheet used for a circuit board or a flat panel display member.

  In recent years, the spread of wireless communication technologies including mobile phones has been remarkable. A conventional mobile phone uses a quasi-microwave band of 800 MHz to 1.5 GHz. However, as the amount of information increases, there is a wireless technology that changes a carrier frequency from a microwave band having a higher frequency to a millimeter wave band. Proposed and realized. These high-frequency radio circuits are expected to be used as mobile communications and network devices, and are becoming increasingly important technologies especially when used in Bluetooth (Bluetooth) and ITS (Intelligent Transport System). .

  In order to realize these high-frequency circuits, the substrate material used there must also have excellent high-frequency transmission characteristics in the wavelength band used, that is, 1 to 100 GHz. In order to realize excellent high-frequency transmission characteristics, it is necessary to have low dielectric constant and low dielectric loss, high processing accuracy, and good dimensional stability, and ceramic substrates are especially promising. It was.

  As a method for producing a ceramic green sheet having excellent dimensional stability and capable of fine processing, a method of forming a via hole by photolithography on a green sheet formed from a photosensitive ceramic composition has been proposed (see Patent Document 1). Yes. As a method of manufacturing a ceramic sheet that forms a higher-definition pattern, for example, focusing on the scattering and reflection of exposure light, the refractive index of the organic component and that of the inorganic component are matched in order to improve light transmission and straightness. There is a method (see Patent Documents 2 and 3). However, these techniques have a drawback that it is difficult to form a via hole of 100 μm or less accurately and uniformly on a substrate (sheet) having a thickness exceeding 100 μm, and a residue remains.

  As a method of performing pattern processing with a high aspect ratio, a method of performing double-sided exposure (see Patent Document 4) has been proposed. Since double-sided exposure is performed simultaneously from the top and bottom surfaces of the sheet, pattern processing can be performed on a ceramic green sheet having a film thickness twice that of normal single-sided exposure. However, these techniques have complicated processes, require a special exposure apparatus, and have disadvantages such as poor position accuracy.

In addition, as a photosensitive sheet having a photosensitive layer having a high resolution and capable of forming a high-strength cured layer, there is a photosensitive transfer sheet composed of two layers having different sensitivities (see Patent Document 5). ). With these techniques, it is possible to form hardened layers having different thicknesses by changing the amount of light irradiation, but it has not been possible to form a pattern with a high aspect ratio.
JP-A-6-202323 (pages 4-9) JP-A-10-171106 (8th to 13th paragraphs) JP-A-10-265270 (7th to 10th paragraphs) JP 10-209334 A (paragraph 62, Examples 1 to 11) JP-A-2005-55656 (Claims 1 to 13)

  SUMMARY OF THE INVENTION An object of the present invention is to provide a photosensitive sheet that does not require a complicated process and does not require a special exposure apparatus, and can obtain a pattern processability with a high aspect ratio.

  That is, a photosensitive sheet that contains a photosensitive organic component and inorganic particles and can be patterned by photolithography, and in the wavelength region of 320 to 780 nm, in the thickness direction of the sheet with respect to the entire film thickness from the light receiving surface. Photosensitive sheet having a light transmittance Ta of 10% and a light transmittance Tb of 10% in the sheet thickness direction with respect to the total film thickness from the surface opposite to the light receiving surface, Tb> Ta Achieved by:

  According to the present invention, it is possible to pattern a via hole with a high aspect ratio by a simpler method than before.

  The present invention is a photosensitive sheet that includes a photosensitive organic component and an inorganic powder and can be patterned by photolithography, and in the light of a wavelength region of 320 to 780 nm, The light transmittance Ta of 10% portion in the thickness direction and the light transmittance Tb of 10% portion in the thickness direction of the sheet with respect to the total film thickness from the surface opposite to the light receiving surface satisfy Tb> Ta. It is a photosensitive sheet. Hereinafter, the photosensitive sheet will be described in detail.

  The light transmittance referred to in the present invention represents a ratio of transmitting through an object without being reflected or absorbed by the object when a light beam typified by visible light or ultraviolet light is irradiated on the object. A parallel light transmittance that represents the transmittance of only the parallel light beam that has passed through the object relative to the irradiated light beam, or a total transmittance that represents the transmittance of all the light beams that have passed through the object relative to the irradiated light beam. There is light transmittance. In addition, the light transmittance in this invention irradiates the light of the wavelength range 320-780 nm which applied the Devis Gibson filter to the light irradiated from the standard light source A (the light irradiated from the standard light source C: Based on JISZ8720-1983 edition) The total light transmittance obtained when

  The 10% portion in the thickness direction of the sheet from the surface receiving the irradiated light (hereinafter referred to as the surface) represents the vicinity of the entire surface of the sheet, and the surface opposite to the surface receiving the irradiated light (hereinafter referred to as the back surface). The 10% portion in the sheet thickness direction represents the vicinity of the back surface of the entire sheet. If the photosensitive sheet satisfies the relationship of Tb> Ta in the light transmittance Ta near the front surface and the light transmittance Tb near the back surface, for example, the same film thickness as compared with a general photosensitive sheet where Tb = Ta. In this case, the amount of light reaching near the back surface of the photosensitive sheet increases. That is, pattern processing with a higher aspect ratio can be performed than the photosensitive sheet with Tb = Ta.

  The photosensitive sheet of the present invention preferably has, for example, a layer structure having at least two layers in order to increase the amount of light reaching the vicinity of the back surface and obtain high aspect ratio pattern processability. It is preferable that the compositions of these are different. That the photosensitive sheet is composed of layers means that the layers are overlapped substantially in parallel with the light irradiation direction. Here, when a cross section obtained by cutting the photosensitive sheet in the light irradiation direction is observed with an electron microscope such as SEM, an interface-like material can be seen as a separate layer. In the photosensitive sheet, layers with different light transmittance can be formed by changing the composition of each layer, and the amount of light reaching near the back surface is increased by making the layer near the back surface a layer with high light transmittance. Pattern processing with a high aspect ratio can be obtained. Note that the difference in the composition of the layers means that the components constituting the layers are different, the concentration ratios of the respective components are different even if the components are the same. The light transmittance of each layer is the type and concentration of the light absorbing agent that absorbs light, the particle size of the inorganic powder that reflects and scatters light, the dispersion state in the photosensitive sheet, the refractive index of the photosensitive organic component and the inorganic powder, etc. Can be controlled by appropriately changing so that the required light transmittance can be obtained. In particular, it can be easily controlled by changing the type and concentration of the light absorbing agent.

  As the absorbent used in the present invention, an organic dye, particularly an organic dye having a high UV absorption coefficient in a wavelength range of 350 to 450 nm is preferably used. Specifically, azo dyes, amino ketone dyes, xanthene dyes, quinoline dyes, amino ketone dyes, anthraquinone dyes, benzophenone dyes, diphenyl cyanoacrylate dyes, triazine dyes, p-aminobenzoic acid dyes, and the like can be used. . Even when an organic dye is added as an ultraviolet absorber, it is preferable because it does not remain in the substrate after baking and the deterioration of the insulating film characteristics due to the ultraviolet absorber can be reduced. Of these, azo dyes and benzophenone dyes are preferable. The addition amount of the organic dye in the paste is preferably 0.01 to 5% by weight. More preferably, it is 0.02 to 1% by weight. If it is less than 0.01% by weight, the effect of adding an ultraviolet absorber is reduced, and if it exceeds 5% by weight, the properties of the insulating film after firing are deteriorated.

Specific examples of the photosensitive sheet of the present invention include a sheet having a layer structure as shown in FIGS. FIG. 1 shows a photosensitive sheet composed of two layers having the same film thickness. The light transmittance of the photosensitive sheet layer 13 formed on the support 11 with respect to the irradiation light 14 is determined by the photosensitive sheet layer. It is higher than the light transmittance of 12. FIG. 2 shows a photosensitive sheet composed of three layers having the same film thickness. The light transmittance T ₂₃ of the photosensitive sheet layer ₂₃ is higher than the light transmittance T ₂₁ of the photosensitive sheet layer 21. It is preferable light transmittance _{T 22} of the photosensitive sheet layer 22 is a transmittance that satisfies _{T 21 ≦ T 22 ≦ T 23} . In such a case, different layers having the same composition may be included in the photosensitive sheet. FIG. 3 shows a photosensitive sheet composed of three layers having different film thicknesses. The light transmittance of the photosensitive sheet layer 33 is higher than the light transmittance of the photosensitive sheet layer 31. Moreover, the film thickness of each layer of the photosensitive sheet layers 31, 32, and 33 is different. The film thickness of each layer constituting the photosensitive sheet is not particularly limited. When there are a plurality of layers, the thicknesses of all the existing layers may be the same or different. As described above, in order to increase the amount of light reaching the vicinity of the back surface of the photosensitive sheet and obtain a high aspect ratio pattern processability, the photosensitive sheet is formed of layers having different light transmittances.

Further, in the photosensitive sheet, for example, a sheet is 10% portion in the sheet thickness direction with respect to the film thickness of the entire sheet from the light receiving surface, and the sheet with respect to the entire film thickness of the sheet from the surface opposite to the light receiving surface. For the 80% portion of the total thickness of the sheet, excluding the 10% portion in the thickness direction, the light transmittance of each portion divided into 8 portions of 10% in the sheet thickness direction from the surface close to the light receiving surface Tb ≧ T ₈ ≧ T ₇ ≧ T ₆ ≧ T ₅ ≧ T ₄ when T ₁ , T ₂ , T ₃ , T ₄ , T ₅ , T ₆ , T ₇ , T ₈ are set from the side close to the surface to be irradiated. It is preferable that the photosensitive sheet satisfy ≧ T ₃ ≧ T ₂ ≧ T ₁ ≧ Ta and Tb> Ta. This is a layer structure in which the light transmittance increases as the distance from the vicinity of the front surface to the vicinity of the back surface increases. Since light loss is small and sufficient light is transmitted to the back surface, pattern processing with a high aspect ratio is possible, which is preferable.

  In the present invention, the light transmittance of the photosensitive sheet is preferably Ta ≧ 50% and Tb ≧ 70%. If Ta <50%, most of the light is absorbed and scattered in the vicinity of the surface of the photosensitive sheet, which is not preferable because sufficient light is not transmitted to the vicinity of the back surface and high aspect ratio pattern processing cannot be performed. If it is 70%, the light transmission near the back surface is deteriorated and pattern processing with a high aspect ratio cannot be performed, which is not preferable. In order to transmit sufficient light to the vicinity of the back surface while suppressing light absorption / scattering near the surface of the photosensitive sheet, the difference in light transmittance (Tb−Ta) between the vicinity of the front surface and the back surface is Tb−Ta. It is preferable that ≧ 10%. If Tb-Ta <10%, it is not preferable because the vicinity of the front surface is cured by scattered light or the like when exposure is performed sufficiently to cure the vicinity of the back surface of the photosensitive sheet.

  In the present invention, in order for the photosensitive sheet to maintain high pattern processability, the film thickness of the entire photosensitive sheet is preferably 20 to 300 μm. If the film thickness is less than 20 μm, it is not preferable because it is difficult to maintain the layer structure and shape of the sheet, and if it exceeds 300 μm, it is not preferable because sufficient light is not transmitted to the lower part of the sheet and high aspect ratio pattern processing cannot be performed. The film thickness of the photosensitive sheet that enables high aspect ratio pattern processing while maintaining the layer structure and shape of the sheet is more preferably 30 to 200 μm, and even more preferably 50 to 150 μm.

  In the present invention, the photosensitive organic component refers to the total of organic components in the photosensitive composition forming the photosensitive sheet. In the present invention, the photosensitive composition is a paste body in which a solvent is suitably used for application and lamination, but the following are parameters relating to the composition of the photosensitive organic component (content ratio of each component, etc.) In the explanation of, the calculation is made by excluding the solvent component in principle.

  The photosensitive organic component in the present invention preferably contains a polymer having an acidic group, an ethylenically unsaturated group-containing compound, a polymerization initiator and the like.

  The polymer having an acidic group may be any polymer having an acidic group, but is preferably a polymer having a carboxyl group, more preferably an ethylenically unsaturated group and a carboxyl group in the side chain. It is a polymer having By having an ethylenically unsaturated group in the side chain, pattern formation is improved, and by containing a carboxyl group in the side chain, development with an aqueous alkaline solution is possible. Such polymers include, for example, carboxyl group-containing monomers such as acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid, vinyl acetate or their anhydrides and methacrylic acid esters, acrylic acid esters, styrene , A monomer such as acrylonitrile, vinyl acetate, 2-hydroxyethyl acrylate and the like, polymerized or copolymerized using a radical polymerization initiator to obtain a polymer, and then a mercapto group which is an active hydrogen-containing group in the polymer, It can be obtained by addition reaction of an ethylenically unsaturated compound having a glycidyl group or an isocyanate group, an acrylic acid chloride, a methacrylic acid chloride or an allyl chloride with respect to an amino group, a hydroxyl group or a carboxyl group. is not. Examples of the ethylenically unsaturated compound having a glycidyl group include glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, glycidyl crotonic acid, and glycidyl isocrotonic acid. Examples of the ethylenically unsaturated compound having an isocyanate group include acryloyl isocyanate, methacryloyl isocyanate, acryloylethyl isocyanate, and methacryloylethyl isocyanate. Further, an ethylenically unsaturated compound having glycidyl group or isocyanate group, acrylic acid chloride, methacrylic acid chloride or allyl chloride may be added in an amount of 0.05 to 0.95 mole equivalent to the active hydrogen-containing group in the polymer. preferable. When the active hydrogen-containing group is a mercapto group, amino group, or hydroxyl group, the entire amount can be used for introduction of a side chain group, but in the case of a carboxyl group, it is added so that the acid value of the polymer is within a preferable range. It is preferable to adjust the amount.

  The acid value of the polymer having an acidic group is preferably 50 to 200 mgKOH / g. By setting the acid value to 50 mgKOH / g or more, the solubility of the soluble part in the developer is not lowered, and by setting the acid value to 200 mgKOH / g or less, the development allowable width can be widened. Since the polymer having an acidic group has a low thermal decomposition temperature during firing, a copolymer containing acrylic acid ester, methacrylic acid ester, acrylic acid, or methacrylic acid as a copolymerization component is preferably used. The weight average molecular weight of the polymer having an acidic group is preferably 5000 to 100000, more preferably 15000 to 75000, and still more preferably 20000 to 50000. If it is in the said range, a softness | flexibility is favorable and the solubility at the time of image development is also favorable. The molecular weight is measured in terms of polystyrene using GPC.

  As for Tg (glass transition temperature) of the polymer which has an acidic group, -60-30 degreeC is preferable. By setting Tg to −60 ° C. or higher, the tackiness of the sheet can be reduced, and by setting Tg to 30 ° C. or lower, the flexibility of the sheet can be maintained. The Tg for maintaining the flexibility while reducing the adhesiveness of the sheet is more preferably −40 to 30 ° C., and further preferably −20 to 30 ° C. The Tg of the polymer was measured by using a DSC-50 type measuring device manufactured by Shimadzu Corporation. The sample was heated at a heating rate of 20 ° C./min under a nitrogen flow and the sample was 10 mg. The starting temperature was Tg.

  The addition amount of the polymer having an acidic group is preferably 10 to 80% by weight in the photosensitive organic component. If the amount added is less than 10% by weight in the photosensitive organic component, a sheet cannot be formed, whereas if it exceeds 80% by weight, a pattern cannot be formed on the sheet.

  The ethylenically unsaturated group-containing compound is used to more effectively perform pattern formation with light. The molecular structure of the ethylenically unsaturated group-containing compound is not limited in any way, such as linear, branched, cyclic, or combinations thereof, but linear is preferable from the viewpoint of compatibility. The weight average molecular weight of the ethylenically unsaturated group-containing compound is preferably 100 to 100,000, more preferably 100 to 50,000, and still more preferably 300 to 45,000. If it is in the said range, a softness | flexibility is favorable and the solubility at the time of image development is also favorable.

  In view of crosslinking reactivity, the ethylenically unsaturated group contained in the ethylenically unsaturated group-containing compound in the present invention is generally preferred to have a small steric hindrance and a large degree of freedom of molecular motion. Accordingly, monosubstitution and then disubstitution are preferred. Specific examples include a vinyl group, an allyl group, an acryloyl group, and a methacryloyl group. In particular, it preferably has an acryloyl group or a methacryloyl group.

  Specific examples of the compound having an acryloyl group or a methacryloyl group include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, sec-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, n-pentyl acrylate, Allyl acrylate, benzyl acrylate, butoxyethyl acrylate, butoxytriethylene glycol acrylate, cyclohexyl acrylate, dicyclopentanyl acrylate, dicyclopentenyl acrylate, 2-ethylhexyl acrylate, glycerol acrylate, glycidyl acrylate, heptadecafluorodecyl acrylate, 2-hydroxy Ethyl acrylate, isobornyl acrylate 2-hydroxypropyl acrylate, isodexyl acrylate, isooctyl acrylate, lauryl acrylate, 2-methoxyethyl acrylate, methoxyethylene glycol acrylate, methoxydiethylene glycol acrylate, octafluoropentyl acrylate, phenoxyethyl acrylate, stearyl acrylate, trifluoroethyl acrylate, Acrylamide, aminoethyl acrylate, phenyl acrylate, phenoxyethyl acrylate, 1-naphthyl acrylate, 2-naphthyl acrylate, thiophenol acrylate, benzyl mercaptan acrylate, acrylate of phenol-ethylene oxide adduct, acrylate of paracumylphenol-ethylene oxide adduct , Nylphenol ethylene oxide adduct acrylate, allylated cyclohexyl diacrylate, 1,4-butanediol diacrylate, 1,3-butylene glycol diacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, polyethylene Glycol diacrylate, glycerol diacrylate, methoxylated cyclohexyl diacrylate, neopentyl glycol diacrylate, propylene glycol diacrylate, tripropylene glycol diacrylate, polypropylene glycol diacrylate, triglycerol diacrylate, bisphenol A diacrylate, bisphenol A-ethylene Diacrylate of oxide adduct, Examples include, but are not limited to, diacrylates of bisphenol A-propylene oxide adducts and those in which some or all of these acrylates are replaced with methacrylates.

  The ethylenically unsaturated group-containing compound may have an organic group (bond) in addition to the ethylenically unsaturated group. Examples of such an organic group (bond) include an alkylene oxide group, an alkyl group, an aryl group, an arylene group, an aralkyl group, a hydroxyalkyl group, and a urethane bond. Among these, polar groups such as alkylene oxide, particularly ethylene oxide are preferable from the viewpoint of compatibility. The ethylene oxide content in the ethylenically unsaturated group-containing compound is preferably 8 to 70% by weight with respect to the ethylenically unsaturated group-containing compound. Among such compounds, a compound containing ethylene oxide and propylene oxide is particularly preferable because of its good thermal decomposability.

  The addition amount of the ethylenically unsaturated group-containing compound is preferably 10 to 80% by weight in the photosensitive organic component. If the amount added is less than 10% by weight in the photosensitive organic component, a sheet cannot be formed, whereas if it exceeds 80% by weight, a pattern cannot be formed on the sheet.

  Polymers having acidic groups and compounds containing ethylenically unsaturated groups, which are contained in the photosensitive organic component, generally have a low ability to absorb actinic light energy. It is preferable to add a polymerization initiator. A sensitizer may be used to assist the effect of the photopolymerization initiator. Such photopolymerization initiators are of different types in terms of mechanism, such as single-molecule direct cleavage type, ion-pair electron transfer type, hydrogen abstraction type, and two-molecule complex system. The photopolymerization initiator used in the present invention is preferably one that generates active radical species.

  Specific examples of the photopolymerization initiator include benzophenone, methyl o-benzoylbenzoate, 4,4-bis (dimethylamine) benzophenone, 4,4-bis (diethylamino) benzophenone, 4,4-dichlorobenzophenone, and 4-benzoyl. -4-methyldiphenyl ketone, dibenzyl ketone, fluorenone, 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenyl-2-phenylacetophenone, 2-hydroxy-2-methylpropiophenone, pt -Butyldichloroacetophenone, thioxanthone, 2-methylthioxanthone, 2-chlorothioxanthone, 2-isopropylthioxanthone, diethylthioxanthone, benzyl, benzyldimethylketanol, benzylmethoxyethyl acetal, benzoin, ben Inmethyl ether, benzoin butyl ether, anthraquinone, 2-t-butylanthraquinone, 2-amylanthraquinone, β-chloroanthraquinone, anthrone, benzanthrone, dibenzosuberone, methyleneanthrone, 4-azidobenzalacetophenone, 2,6-bis (P-azidobenzylidene) cyclohexanone, 2,6-bis (p-azidobenzylidene) -4-methylcyclohexanone, 2-phenyl-1,2-butadion-2- (o-methoxycarbonyl) oxime, 1-phenyl-propane Dione-2- (o-ethoxycarbonyl) oxime, 1,3-diphenyl-propanetrione-2- (o-ethoxycarbonyl) oxime, 1-phenyl-3-ethoxy-propanetrione-2- (o-benzoyl) oxy , Michler's ketone, 2-methyl- [4- (methylthio) phenyl] -2-morpholino-1-propanone, naphthalenesulfonyl chloride, quinolinesulfonyl chloride, N-phenylthioacridone, 4,4-azobisisobutyronitrile , Diphenyl disulfide, benzthiazole disulfide, triphenylphosphine, camphorquinone, carbon tetrabromide, tribromophenyl sulfone, benzoin peroxide and eosin, methylene blue and other reducing agents such as ascorbic acid and triethanolamine The combination etc. are mentioned. Specific examples of the sensitizer include 2,4-diethylthioxanthone, isopropylthioxanthone, 2,3-bis (4-diethylaminobenzal) cyclopentanone, 2,6-bis (4-dimethylaminobenzal) cyclohexanone, 2,6-bis (4-dimethylaminobenzal) -4-methylcyclohexanone, Michler's ketone, 4,4-bis (diethylamino) -benzophenone, 4,4-bis (dimethylamino) chalcone, 4,4-bis (diethylamino) ) Chalcone, p-dimethylaminocinnamylidene indanone, p-dimethylaminobenzylidene indanone, 2- (p-dimethylaminophenylvinylene) -isonaphthothiazole, 1,3-bis (4-dimethylaminobenzal) acetone 1,3-carbonyl-bis (4-diethylamino) Benzal) acetone, 3,3-carbonyl-bis (7-diethylaminocoumarin), N-phenyl-N-ethylethanolamine, N-phenylethanolamine, N-tolyldiethanolamine, isoamyl dimethylaminobenzoate, isoamyl diethylaminobenzoate, Examples include 3-phenyl-5-benzoylthiotetrazole and 1-phenyl-5-ethoxycarbonylthiotetrazole. In the present invention, one or more photopolymerization initiators and sensitizers can be used. The addition amount of the photopolymerization initiator is preferably 0.05 to 10% by weight with respect to the photosensitive organic component. By setting the addition amount of the photopolymerization initiator within this range, good photosensitivity can be obtained. When adding a sensitizer, the addition amount is preferably 0.05 to 30% by weight, more preferably 0.1 to 20% by weight, based on the photosensitive organic component. If the amount of the sensitizer is too small, the effect of improving the photosensitivity is not exhibited, and if the amount of the sensitizer is too large, the residual ratio of the exposed portion may be too small.

  Furthermore, it is preferable to add a polymerization inhibitor. Specific examples of the polymerization inhibitor include hydroquinone, monoester of hydroquinone, N-nitrosodiphenylamine, phenothiazine, pt-butylcatechol, N-phenylnaphthylamine, 2,6-di-tert-butyl-p- Examples include methylphenol, chloranil, and pyrogallol. When adding a polymerization inhibitor, the addition amount is preferably 0.001 to 1% by weight with respect to the photosensitive composition.

  Moreover, you may add a plasticizer and antioxidant. Specific examples of the plasticizer include dibutyl phthalate, dioctyl phthalate, polyethylene glycol, glycerin and the like. Specific examples of antioxidants include 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-4-ethylphenol, 2,2-methylene-bis (4 -Methyl-6-tert-butylphenol), 2,2-methylene-bis (4-ethyl-6-tert-butylphenol), 4,4-bis (3-methyl-6-tert-butylphenol), 1,1, 3-tris (2-methyl-6-tert-butylphenol), 1,1,3-tris (2-methyl-4-hydroxy-tert-butylphenyl) butane, bis [3,3-bis (4-hydroxy- 3-t-butylphenyl) butyric acid] glycol ester, dilauryl thiodipropionate, triphenyl phosphite and the like. When adding antioxidant, the addition amount is preferably 0.001 to 1% by weight with respect to the paste composition.

  The amount of the photosensitive organic component in the photosensitive composition is preferably 10 to 40% by weight, more preferably 15 to 35% by weight. If the blending amount is 10 to 40% by weight, both the flexibility and breathability characteristics of the sheet can be satisfied.

  The photosensitive composition used in the present invention is as follows. First, a photosensitive organic component, for example, a polymer having a carboxyl group and an ethylenically unsaturated group in the side chain, if necessary, a compound having an ethylenically unsaturated group, an ion catalyst, a photopolymerization initiator, a solvent and various additives Etc. are mixed and then filtered to produce an organic vehicle. To this, a pretreated inorganic powder is added if necessary, and the mixture is uniformly mixed and dispersed by a kneader such as a ball mill or a three-roll mill to produce a slurry or paste of the photosensitive composition. The viscosity of the slurry or paste is appropriately adjusted depending on the blending ratio of the inorganic powder and the photosensitive organic component, the amount of the organic solvent, and the addition ratio of the plasticizer and other additives, but the range is preferably 2 to 200 Pa · s.

  The solvent used in preparing the slurry or paste may be any solvent that can dissolve the photosensitive organic component. For example, methyl cellosolve, ethyl cellosolve, butyl cellosolve, methyl ethyl ketone, dioxane, acetone, cyclohexanone, cyclopentanone, isobutyl alcohol, isopropyl alcohol, tetrahydrofuran, dimethyl sulfoxide, γ-butyrolactone, 3-methylmethoxybutanol, toluene , Trichloroethylene, methyl isobutyl ketone, isophorone, methylmethoxybutanol, benzyl alcohol, N-methylpyrrolidone, dimethylacetamide and the like may be used alone or in combination. The amount of the organic solvent contained in the paste varies depending on the intended use, and is not limited as long as it is in the viscosity range. For example, in the application stage, the paste (excluding inorganic powder) It is preferable that 10-30 weight% is contained in.

  The photosensitive composition used in the present invention contains an inorganic powder as an essential component in addition to the photosensitive organic component. This inorganic powder is sintered in the firing step, and so-called low-temperature fired inorganic powder is preferred because firing at a temperature of 1000 ° C. or less, particularly 450 to 900 ° C. is preferable in the formation of the substrate targeted by the present invention. Of course, since these inorganic powders determine basic physical properties such as electrical characteristics, strength, and thermal expansion coefficient of the substrate, they are selected according to the intended characteristics.

The component useful as the inorganic powder used in the present invention includes six embodiments.
In the first aspect, the general formula R _x O—Al ₂ O ₃ —SiO ₂ -based material (when x = 1, R is selected from an alkaline earth metal, and when x = 2, R is from an alkali metal). Selected). Although it is not particularly limited, it is anorthite (CaO—Al ₂ O ₃ -2SiO ₂ ), Celsian (BaO—Al ₂ O ₃ -2SiO ₂ ), etc., and is an inorganic powder used as a low-temperature sintered ceramic material. is there.

  The inorganic powder of the second aspect is composed of 50 to 90% by weight of borosilicate glass powder and 10 to 50% by weight of quartz powder and / or amorphous silica powder. At this time, it is preferable that the high purity silica (quartz) does not melt with the borosilicate glass. Further, spherical silica is preferable because the slurry can be filled more easily.

  The third aspect is at least selected from the group of 30-60% by weight borosilicate glass powder, 20-50% by weight quartz powder and / or amorphous silica powder, and cordierite, spinel, forsterite, anorthite and serdian. It is a mixture of 20 to 50% by weight of one kind of ceramic powder.

In a fourth aspect, _SiO glass powder is oxide equivalent representation 2: 30-70 _{wt%, Al} 2 O 3: _5~40 wt%, CaO: 3 to 25 _{wt%, B} 2 O 3: _3~50 30% to 70% by weight of a glass powder having an embodiment shown in the above composition as an inorganic powder in a composition range of wt%, alumina, zirconia, magnesia, beryllia, mullite, cordierite, spinel, forsterite, It is a mixture with 30 to 70% by weight of at least one ceramic powder selected from the group of anorthite, serdian, silica and aluminum nitride.

Fifth aspect, _SiO 2 in terms of oxide notation: 80-90 _{wt%, B} 2 O 3: _{10~15 wt%, Al} 2 O 3: _{0~5 wt%,} K 2 O: _0~5 by weight % Is an inorganic powder contained at a ratio of%.

In a sixth aspect, the glass powder is an oxide _notation, SiO 2: 45 to 60 _{wt%, Al} 2 O 3: _{0.1~10 wt%, B} 2 O 3: _9~24 wt%, CaO: 2 15 wt%, MgO: 0.1 to 12 _wt%, Na 2 O: _{0.1~1.5 wt%,} ZrO 2: _{0.1~5 wt%,} K 2 O: _0.1~1 weight %, TiO ₂ : 0.1 to 5% by weight, and inorganic powder is 30 to 70% by weight of glass powder having the embodiment shown in the above composition, alumina, zirconia, magnesia, beryllia, mullite , Spinel, forsterite, anorcite, serdian, cordierite, and aluminum nitride, and a mixture of 30 to 70% by weight of ceramic powder.

  The ceramic powder as the filler component in the fourth and sixth embodiments is effective for improving the mechanical strength of the substrate and controlling the thermal expansion coefficient. In particular, alumina, zirconia, mullite, cordierite, and anorthite have excellent effects. By mixing these ceramic powders, the firing temperature can be set to 800 to 900 ° C., and the strength, dielectric constant, thermal expansion coefficient, sintered density, volume resistivity, and shrinkage rate can be set as desired characteristics.

  In the present invention, the average particle diameter of the inorganic powder is preferably 500 nm or less so that the photosensitive sheet maintains high pattern processability. The average particle size of the inorganic powder is more preferably 300 nm or less, and further preferably 150 nm or less. By combining an inorganic powder with a size equal to or smaller than the wavelength of active light (500 nm to 350 nm) effective for pattern processing, light scattering during active light irradiation is reduced, and the lower part of the sheet is exposed. . As a result, high definition and high aspect ratio pattern processing becomes possible. If the average particle diameter exceeds 500 nm, the ratio of light scattering increases and actinic rays do not reach the deep part. Alternatively, since the periphery of the pattern is exposed by scattered light, the obtained pattern may not have a high definition and a high aspect ratio. The content of the inorganic powder having an average particle size of 500 nm or less varies depending on the use, but is preferably 5 to 90 wt. The dielectric constant characteristic after baking is maintained by setting it as 5 weight% or more. On the other hand, the light transmittance of a sheet | seat can be hold | maintained by setting it as 90 weight% or less.

  The inorganic powder used in the present invention can be fired at 600 to 900 ° C. when Cu, Ag, Au or the like is multilayered as a wiring conductor, and has a thermal expansion coefficient approximate to that of a chip component or a printed circuit board. It is necessary to select a material that provides a substrate having a low dielectric constant and low dielectric loss even in a high frequency region.

  The photosensitive sheet preferably used in the present invention includes a photosensitive composition having a photosensitive organic component and an inorganic powder, and the photosensitive composition is generally used for a doctor blade method, an extrusion molding method, a slit die, a screen printing method, and the like. In this way, it can be formed on a support such as polyester, polyphenylene sulfide (PPS), polyethylene terephthalate (PET), glass, glass ceramics, aluminum, steel, etc., which have been subjected to various coating treatments as required. The photosensitive sheet comprising the support and the photosensitive composition is formed by removing the solvent by drying.

  As a method for forming the photosensitive sheet into a layer structure of two or more layers, the photosensitive composition may be applied to the support a plurality of times by the above method, or separately prepared photosensitive sheets may be laminated. Moreover, when changing the composition of each layer, the photosensitive composition of a different composition may be apply | coated several times, and the photosensitive sheet of a different composition may be laminated | stacked. When the photosensitive composition is applied a plurality of times, baking is preferably performed after the first application and before the second and subsequent applications. By doing so, the photosensitive composition apply | coated 1st time can dry and the reduction | decrease of the sheet | seat thickness at the time of the 2nd application | coating can be prevented. Although the baking temperature and time vary depending on the photosensitive composition, it is preferably applied at 50 to 100 ° C. for about 5 to 30 minutes. Baking is preferably performed in a convection baking furnace or an IR baking furnace. When laminating photosensitive sheets, it is preferable to stack a required number of photosensitive sheets and bond them at a temperature of 80 to 150 ° C. with a pressure of 5 to 25 MPa to produce a multilayer sheet.

Next, as a method of irradiating the photosensitive sheet with actinic rays in a pattern, there are a method of irradiating actinic rays through a photomask having patterns such as via holes and cavities, and a method of directly drawing a pattern using laser light. Can be mentioned. Examples of the actinic rays to be irradiated here include infrared rays, near infrared rays, visible rays, ultraviolet rays, and X-rays. Among these, ultraviolet rays are preferably used. The light source used for ultraviolet rays is particularly preferably an ultrahigh pressure mercury lamp, but is not necessarily limited thereto. Although the exposure amount varies depending on the thickness of the photosensitive sheet and the sensitivity of the material, it is preferable to perform the exposure for 1 second to 30 minutes in the case of an ultrahigh pressure mercury lamp with an output of 0.5 to 100 mW / cm ² . In addition, the alignment guide hole at the time of lamination | stacking of the photosensitive sheet | seat after pattern processing can be formed with the same method as the via hole formation.

  Next, the photosensitive sheet irradiated with actinic rays is treated with a developing solution to dissolve and remove the portion that is soluble in the developing solution (the portion that is not irradiated with actinic rays in the negative type and the active ray irradiating portion in the positive type). A pattern is formed in the photosensitive sheet. As a developing method of the photosensitive sheet, an immersion method, a spray method, an ultrasonic method or a combination thereof can be performed. A development method for forming a uniform pattern with little damage to the photosensitive sheet is preferably an ultrasonic method, and more preferably a frequency modulation type ultrasonic method.

  The development method using ultrasonic waves is a method of accelerating the dissolution and removal of the soluble part by irradiating ultrasonic waves in addition to the developer, and obtaining a fine pattern on the photosensitive sheet. In addition, by continuously modulating and irradiating the fundamental frequency of the ultrasonic wave with a predetermined width, the distribution of ultrasonic stress is eliminated, damage to the photosensitive sheet is reduced, and a photosensitive sheet on which a uniform pattern is formed is provided. obtain. In the present invention, the frequency modulation range of the ultrasonic waves is preferably 20 to 50 KHz. When the frequency is lower than 20 KHz, the ultrasonic stress becomes stronger than necessary, and the damage to the photosensitive sheet increases. On the other hand, if it exceeds 50 KHz, the ultrasonic stress becomes weak, and the erosion of the developer in the soluble part becomes weak.

The work density of the ultrasonic wave per substrate area is preferably 40 to 100 W / cm ² . If the work density is lower than 40 W / cm ² , the soluble part may not be completely removed. On the other hand, if the work density is higher than 100 W / cm ² , the remaining part of the pattern (in the case of negative type, actinic ray irradiation part, in the case of positive type) The portion exposed to no actinic rays (hereinafter referred to as the cured portion) is eroded by the developer and damages to the photosensitive sheet, and the ultrasonic development time is preferably 5 to 120 seconds. On the other hand, it is not preferable because the soluble part cannot be completely removed, and on the other hand, if it exceeds 120 seconds, it is not preferable because erosion of the cured part and damage to the photosensitive sheet increase. The ultrasonic development time for suppressing erosion and damage to the photosensitive sheet is more preferably 5 to 60 seconds, and further preferably 10 to 30 seconds.

In the present invention, the irradiation position of the ultrasonic wave on the photosensitive sheet is not particularly limited, but it is preferable that the photosensitive sheet is positioned so as to be perpendicular to the ultrasonic direction and irradiated from the surface side. Further, the substrate may be moved in the developer such as vibrating, rotating, or reciprocating. Alternatively, the developer may be circulated and vibrated.
The developing method used in the present invention is preferably used in combination with a developing method such as an immersion method or a spray method. The so-called immersion method is a method in which, for example, a photosensitive sheet after exposure is immersed in a developer to advance dissolution / removal of a soluble portion in the developer. Similarly, the spray method is a development method in which the soluble portion of the photosensitive sheet after irradiation with actinic rays is dissolved and removed while utilizing the physical force of the spray. This spray method is particularly preferable because it is always replaced by the outflow of the developing solution, and there is little reduction in the dissolving power of the developing solution, resulting in shortening the developing time. Further, the spray pressure per development substrate area is preferably 0.5 to ²⁰ kg / cm ² . When the spray pressure is less than 0.5 kg / cm ² , the physical force is insufficient and the development time becomes long. On the other hand, if it exceeds 20 kg / cm ² , damage to the photosensitive sheet will increase due to erosion of the developer into the cured portion. The spray pressure for suppressing erosion of the cured portion and damage to the photosensitive sheet while maintaining physical force is more preferably 1 to 10 kg / cm ² , and further preferably 1 to 5 kg / cm ² . By relatively moving the spray spreader and the photosensitive sheet, the developer can be sprayed onto the sheet with the support having a large area with a small number of spreaders, and the developer can be applied to a specific position of the photosensitive sheet. Concentration of spraying is preferably suppressed. Combining these immersion methods, spraying methods and the like with frequency modulation type ultrasonic irradiation leads to shortening of development time, leading to reduction of damage to the photosensitive sheet.

  Any developer can be used as the developer for the photosensitive sheet as long as it has different solubility, swelling, and affinity for the actinic ray-irradiated part and the non-irradiated part of the photosensitive composition. In the present invention, an alkaline aqueous solution is preferable. As the alkali aqueous solution, a metal alkali aqueous solution such as sodium or potassium, or an organic alkali aqueous solution can be used. As the metal alkali aqueous solution, a compound containing an alkali metal such as sodium ion, potassium ion or calcium ion, or an alkaline earth metal ion can be used. Specific examples include sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, potassium carbonate, calcium carbonate, lithium carbonate and the like. As the organic alkaline aqueous solution, a general amine compound can be used. Specific examples include methylamine, n-propylamine, t-butylamine, monoethanolamine, TMAH (tetramethyl hydroxide), and the like. The concentration of the alkaline aqueous solution is preferably 0.01 to 10% by weight. If the concentration of the aqueous alkali solution is less than 0.01% by weight, the soluble part may not be completely removed. On the other hand, if it exceeds 10% by weight, the erosion of the cured part and the peeling of the pattern may occur. The alkali concentration for suppressing the erosion of the cured part and the peeling of the pattern while the removal of the soluble part is sufficiently performed is preferably 0.1 to 5% by weight, more preferably 0.5 to 1.5% by weight. It is. The temperature of the developer is preferably 20 to 50 ° C. in terms of process management.

  For example, when using the developed photosensitive sheet for a circuit board or the like, use a conductor paste or a resistor paste to form a necessary pattern such as filling a via hole or forming a wiring. Can be done. The wiring may be formed by printing with a screen printer or the like, or may be formed by photolithography using a photosensitive conductive paste.

  The photosensitive sheet obtained by the production method of the present invention is processed into a circuit board, a flat panel display member, and the like through a baking process. For example, in a circuit board, a photosensitive sheet having a required number of wiring patterns formed thereon is stacked using guide holes, and bonded at a temperature of 80 to 150 ° C. under a pressure of 5 to 25 MPa, thereby producing a multilayer sheet. A non-sinterable ceramic sheet, which will be described later, may be laminated on both sides of the multilayer sheet and fired. Firing is performed in a firing furnace. The firing atmosphere and temperature vary depending on the type of inorganic powder and organic component in the photosensitive composition, but firing is performed in air, in a nitrogen atmosphere, or in a hydrogen reduction atmosphere. Firing of the photosensitive composition preferably used in the circuit board is first performed at a temperature of 600 to 950 ° C. after a step of decomposing and scattering an organic substance at room temperature to 600 ° C. (debinding step). The circuit ceramic multilayer substrate thus obtained is used as a high-frequency circuit substrate.

  A hard-to-sinter ceramic sheet is a sheet having ceramic powder such as high melting point glass, amorphous silica, quartz, alumina, magnesia, hematite, barium titanate and boron nitride that does not sinter at the substrate sintering temperature. It is called a sheet for use or a restraint sheet. 1 to 5% by weight of oxide powder for improving adhesion to ceramic sheets and oxidizing agents such as lead oxide, bismuth oxide, zinc oxide, manganese oxide, barium oxide, calcium oxide and strontium oxide is added to this sheet It is preferred that As an example of such a hardly sinterable ceramic sheet, an organic powder such as polyvinyl butyral and polymethyl methacrylate, a plasticizer such as dioctyl phthalate, an appropriate oxide, an organic solvent, etc. are added to alumina powder, and a doctor blade. A sheet formed by a method can be used.

  Inevitable shrinkage exists depending on the components and composition of the composition forming the ceramic sheet and various conditions during firing, but by using the constraining sheet, the ceramic sheet is shrunk only in the thickness direction and almost in the XY plane. Can be shrunk. If the shrinkage rate in the XY plane direction can be suppressed to 1% or less, it can be considered that almost no shrinkage has been achieved, but more preferably 0.5% or less, still more preferably 0.1% or less. is there.

  The photosensitive sheet of the present invention is a circuit board for high-density mounting of semiconductor elements that require the formation of fine circuit patterns on the surface layer and inner layer electrodes on the substrate surface, a circuit board for high-frequency radio, particularly a multilayer circuit board, and a flat panel display. It is suitably used for various members.

  Hereinafter, the present invention will be specifically described with reference to examples. The concentration (%) is% by weight unless otherwise specified. The inorganic powder and photosensitive organic component used in the examples are as follows.

A. Photosensitive organic component Polymer I: 0.2 equivalent of glycidyl methacrylate (GMA) with respect to the carboxyl group of a copolymer comprising 40 parts by weight of 2-ethylhexyl acrylate, 40 parts by weight of butyl methacrylate and 20 parts by weight of acrylic acid ) Was subjected to an addition reaction. The obtained polymer I has a weight average molecular weight of 36000, an acid value of 100 mgKOH / g, and Tg of 15 ° C.

  Polymer II: Addition reaction of 0.4 equivalent of glycidyl methacrylate (GMA) to a carboxyl group of a copolymer composed of 30 parts by weight of methyl acrylate, 40 parts by weight of ethyl acrylate, and 30 parts by weight of methacrylic acid I let you. The obtained polymer II has a weight average molecular weight of 19000, an acid value of 107 mgKOH / g, and Tg of 25 ° C.

Ethylenically unsaturated group-containing compound I: polyethylene glycol diacrylate (“M-245” manufactured by Toagosei Co., Ltd.)
Ethylenically unsaturated group-containing compound II: urethane acrylate ("UV6100B" manufactured by Nippon Synthetic Chemical Industry Co., Ltd.)
Ethylenically unsaturated group-containing compound III: acrylic monomer (Nippon Kayaku Co., Ltd. Karayad TPA-330).

Photoinitiator I: “Irgacure 819” (Ciba Specialty Chemicals)
Photopolymerization initiator II: Mixture of 2,4-dimethyl oxanthone (Nippon Kayaku Co., Ltd.) and “Irgacure 369” (Ciba Specialty Chemicals) in a weight ratio of 1: 2 Ultraviolet light absorber: “Sudan IV "(Tokyo Chemical Industry Co., Ltd.)
Dispersant: “Nopcos Perth” (manufactured by San Nopco)
Polymerization inhibitor: p-methoxyphenol (Wako Pure Chemical Industries, Ltd.)
Solvent: “Solfit” (manufactured by Kuraray Co., Ltd.).

B. Inorganic powder Alumina powder I: Average particle size 37 nm
Glass powder I: SiO ₂ (60%), PbO (17.5%), CaO (7.5%), MgO (3%), Na ₂ O (3.15%), K ₂ O (2%) , B ₂ O ₃ (5.8%) composition was used. This glass powder has a glass transition point of 572 ° C., a softening point of 686 ° C., and an average particle diameter of 2 μm.

Glass powder II: Bi ₂ O ₃ (37%), SiO ₂ (7%), B ₂ O ₃ (19%), ZnO (20%), BaO (12%), Al ₂ O ₃ (5%) The composition was used. This glass powder has a glass transition point of 445 ° C., a softening point of 509 ° C., and an average particle size of 0.5 μm.

C. Developer I: 0.5% TMAH aqueous solution Developer II: 0.1% Na ₂ CO ₃ aqueous solution Photosensitive composition The composition shown in Table 1 was mixed to prepare a paste, which was passed five times with three rolls, and then filtered using a 400 mesh filter to prepare a photosensitive composition.

E. Light transmittance measurement The light transmittances Ta and Tb of the photosensitive sheet are measured by using a microtome from the light receiving surface to the entire sheet thickness in the thickness direction of the sheet, 10% portion, and the light receiving surface. A section of 10% of the total thickness of the sheet is prepared from the opposite surface in the sheet thickness direction, and irradiated from a standard light source C of 12 V (volt) 50 W (watt) by a haze computer manufactured by Suga Test Instruments Co., Ltd. The total light transmittance of light having a wavelength region of 320 to 780 nm was measured.

Example 1
Alumina powder I, glass powder I as inorganic powder, ethylenically unsaturated group-containing compound I, ethylenically unsaturated group-containing compound II, polymer I, photopolymerization initiator I, ultraviolet absorber, dispersion as photosensitive organic component A paste was prepared by mixing an agent, a polymerization inhibitor, and a solvent in the composition shown in Table 1, and after passing this through 5 rolls of 3 rolls, the mixture was filtered using a 400 mesh filter and photosensitive composition 1, 2 and 3 were produced. First, the photosensitive composition 1 was applied onto a support PET (polyethylene terephthalate) film using a doctor blade method, and dried at 85 ° C. for 15 minutes to form a first layer. Similarly, a photosensitive composition 2 is formed on the first layer, and further a photosensitive composition 3 is formed on the second layer. Sheet was prepared.

Via pattern / via hole pitch inscribed in 5 μm intervals from 10 μm to 300 μm with respect to the above photosensitive sheet, using a negative chrome mask with 3 times the diameter of the via hole, ultraviolet light with an ultrahigh pressure mercury lamp 5 mW / cm ² from the surface Exposed. The exposure amount was 150 mJ / cm ² .

  Next, pattern development of the photosensitive sheet was performed with the developer I maintained at 25 ° C. After immersing the photosensitive sheet in a bath filled with the developer I for 120 seconds, 38 ± 5 KHz frequency-modulated ultrasonic waves were irradiated for 30 seconds. The developed sheet was evaluated for pattern processability using an optical microscope or an electron microscope. For a photosensitive sheet having a film thickness of 150 μm, the minimum via diameter capable of forming a pattern of 80% or more of the pattern-exposed via holes was 100 μm, and the aspect ratio was 1.5.

Example 2
The composition shown in Table 1 is glass powder II as the inorganic powder, ethylenically unsaturated group-containing compound III, polymer II, photopolymerization initiator II, ultraviolet absorber, dispersant, polymerization inhibitor, and solvent as the photosensitive organic component. A paste was prepared by mixing at 5 and passed 5 times with 3 rolls, followed by filtration using a 400 mesh filter to prepare photosensitive compositions 4 and 5. First, the photosensitive composition 4 was applied on a glass substrate using a screen printing method, and dried at 80 ° C. for 5 minutes to form a first layer. Similarly, the photosensitive composition 2 was formed on the first layer, and a photosensitive sheet having a thickness of 20 μm composed of the two layers shown in Table 2 was produced.

A via pattern / via hole pitch engraved at intervals of 5 μm from 10 μm to 300 μm with respect to the photosensitive sheet described above using a negative chrome mask having a diameter three times the via hole diameter, and an ultraviolet ray with an ultra-high pressure mercury lamp of 0.5 kW output from the surface. Exposed. The exposure amount was 1 J / cm ² .

  Next, pattern development of the photosensitive sheet was performed with Developer II maintained at 25 ° C. The developer II was used for development for 30 seconds by spraying. With respect to a photosensitive sheet having a film thickness of 20 μm, the minimum via diameter capable of forming a pattern of 80% or more of the pattern-exposed via holes was 15 μm, and the aspect ratio was 1.33.

Examples 3-6
In the same manner as in Example 1, photosensitive compositions having the compositions shown in Table 1 were prepared, and photosensitive sheets shown in Table 2 were prepared on the support PET, and the pattern processability was evaluated. The results are shown in Table 2.

Example 7
In the same manner as in Example 1, a photosensitive composition having the composition shown in Table 1 was prepared, and a photosensitive sheet having three layer thicknesses different from those shown in Table 2 was prepared on the support PET to obtain pattern processability. evaluated. For a photosensitive sheet having a film thickness of 150 μm, the minimum via diameter capable of forming a pattern of 80% or more of the pattern-exposed via holes was 105 μm, and the aspect ratio was 1.43.

Comparative Example 1
Alumina powder I, glass powder I as inorganic powder, ethylenically unsaturated group-containing compound I, ethylenically unsaturated group-containing compound II, polymer I, photopolymerization initiator I, ultraviolet absorber, dispersion as photosensitive organic component A paste is prepared by mixing an agent, a polymerization inhibitor, and a solvent in the composition shown in Table 1, and after passing through a three-roll five times, the mixture is filtered using a 400-mesh filter to obtain a photosensitive composition 2. Produced. First, the photosensitive composition 2 was applied onto a support PET using a doctor blade method, and dried at 85 ° C. for 15 minutes to form a first layer. Similarly, a photosensitive composition 2 is formed on the first layer, and further a photosensitive composition 2 is formed on the second layer. Sheet was prepared.

Via pattern / via hole pitch inscribed in 5 μm intervals from 10 μm to 300 μm with respect to the above photosensitive sheet, using a negative chrome mask with 3 times the diameter of the via hole, ultraviolet light with an ultrahigh pressure mercury lamp 5 mW / cm ² from the surface Exposed. The exposure amount was 150 mJ / cm ² .

  Next, pattern development of the photosensitive sheet was performed with the developer I maintained at 25 ° C. After immersing the photosensitive sheet in a bath filled with the developer I for 120 seconds, 38 ± 5 KHz frequency-modulated ultrasonic waves were irradiated for 30 seconds. With respect to a photosensitive sheet of 150 μm, the minimum via diameter capable of forming a pattern of 80% or more of the pattern-exposed via holes was 150 μm, and the aspect ratio was 1.

Comparative Examples 2-5
In the same manner as in Comparative Example 1, a photosensitive composition having the composition shown in Table 1 was prepared, and a photosensitive sheet shown in Table 3 was prepared on the support PET to evaluate pattern workability. The results are shown in Table 3.

Sectional drawing of the photosensitive sheet | seat comprised from two layers from which the film thickness obtained by this invention is the same, and each has a different light transmittance Sectional drawing of the photosensitive sheet comprised from 3 layers with the same film thickness obtained by this invention, and each light transmittance differing Sectional drawing of the photosensitive sheet comprised from three layers from which the film thickness obtained by this invention differs, and each light transmittance differs

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Support body 12 Photosensitive sheet layer 13 Photosensitive sheet layer 14 with higher light transmittance than the photosensitive sheet layer 12 Irradiation light 21 Photosensitive sheet layer 22 Photosensitive sheet layer 23 Light transmittance is higher than the photosensitive sheet layer 21 Large photosensitive sheet layer 31 Photosensitive sheet layer 32 Photosensitive sheet layer 33 Photosensitive sheet layer having a higher light transmittance than the photosensitive sheet layer 31

Claims (4)

A photosensitive sheet containing a photosensitive organic component and an inorganic powder and capable of pattern processing by photolithography, and in the light of a wavelength region of 320 to 780 nm, 10 in the sheet thickness direction with respect to the film thickness of the entire sheet from the light receiving surface. % Light transmittance Ta and a light-sensitive sheet having a light transmittance Tb of 10% portion in the thickness direction of the sheet with respect to the total film thickness from the surface opposite to the light receiving surface, Tb> Ta. The photosensitive sheet according to claim 1, wherein the photosensitive sheet has at least two layers, and the composition of each layer is different. 2. The photosensitive sheet according to claim 1, wherein the light transmittance Ta is Ta ≧ 50% and the light transmittance Tb is Tb ≧ 70%. The photosensitive sheet according to claim 1, wherein the entire photosensitive sheet has a thickness of 20 to 300 μm.

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