JP2010018478A - Photosensitive ceramic composition, photosensitive ceramic sheet, and method for manufacturing photosensitive ceramic sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photosensitive ceramic composition which suppresses warpage of a photosensitive ceramic sheet and peeling of a laminated body in a step of firing the sheet, by a more convenient means with low energy consumption, and to provide a photosensitive ceramic sheet. <P>SOLUTION: The photosensitive ceramic composition comprises a photosensitive organic component, an inorganic powder and a thermal polymerization initiator. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a photosensitive ceramic composition and a photosensitive ceramic sheet. The photosensitive ceramic sheet of the present invention is used for circuit materials such as ceramic multilayer substrates for high-frequency radio, chip inductors for electronic components, and ceramic multilayer electronic components for noise filters.

  The spread of wireless communication technology including mobile phones is 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 and ITS (Intelligent Transport System). .

  In order to realize these high-frequency circuits, the substrate material used therein must also have excellent high-frequency transmission characteristics in the used frequency band, 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.

  However, although the conventional ceramic substrate materials are excellent in dimensional stability, the fine processing degree is low, so that sufficient characteristics cannot be obtained particularly in a high frequency region. As a method for improving such a problem of fine processing accuracy, a via hole forming method using a photolithography technique using a green sheet formed from a photosensitive ceramic composition has been proposed (for example, see Patent Document 1).

  However, when photolithography technology is used, shrinkage due to photopolymerization of the photosensitive organic component in the photolithographic processing step in pattern formation, and photosensitive organic in the step of decomposing the organic substance called the debinding step in the baking step. Component shrinkage due to thermal polymerization may cause problems such as sheet warpage and peeling of the laminate.

As a method for solving these problems, a method has been proposed in which the degree of polymerization of the photosensitive organic component in the sheet is made uniform by irradiating or heat-treating the sheet after the pattern processing step with an actinic ray (for example, Patent Document 2).
JP-A-6-202323 JP 2006-062357 A

  The method described in Patent Document 2 is certainly an effective means for suppressing the warpage of the sheet, but when the light transmittance of the sheet is low or when the film thickness is thick, a large amount of irradiation with actinic rays is performed. In addition, in the case of heat treatment, it is necessary to heat in a high-temperature oven for a long time, so that there are problems that the process time becomes long and the energy used is greatly increased.

  The present invention provides a photosensitive ceramic composition and a photosensitive ceramic sheet which can suppress sheet warpage and peeling of a laminate in a firing process of the photosensitive ceramic sheet with simpler and lower energy consumption means. The task is to do.

  That is, the present invention is a photosensitive ceramic composition characterized by containing a photosensitive organic component, an inorganic powder, and a thermal polymerization initiator, and a photosensitive ceramic sheet produced using the photosensitive ceramic composition.

  With the photosensitive ceramic composition and photosensitive ceramic sheet of the present invention, the degree of polymerization inside the sheet is uniformized by a short heat treatment after the sheet patterning process, and the sheet warpage and laminate peeling in the baking process Can be suppressed.

  The present invention is a photosensitive ceramic composition containing a photosensitive organic component, an inorganic powder, and a thermal polymerization initiator, and a photosensitive ceramic sheet produced using the photosensitive ceramic composition.

  The photosensitive organic component used in the present invention refers to the total of a resin component serving as a binder and an organic component imparting photosensitivity thereto. The photosensitive organic component preferably contains a polymer having an acidic group (component A1), an ethylenically unsaturated group-containing compound (component A2), a photopolymerization initiator, and the like. In the present invention, the photosensitive ceramic composition is a paste body in which a solvent is preferably used for coating and lamination, but the parameters relating to the composition of the photosensitive organic component (content ratio of each component, etc.) In the description, in principle, the calculation is performed excluding the solvent component.

  Component A1 may be any polymer having an acidic group, but is preferably a polymer having a carboxyl group, and more preferably a polymer having an ethylenically unsaturated group and a carboxyl group in the side chain. It is a coalescence. 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, acrylic acid chloride, methacrylic acid chloride or allyl chloride to an amino group, hydroxyl group or carboxyl group, but is not limited to these 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. In addition, the measurement of an acid value is calculated | required based on JIS-K0070 (1992).

  The acid value of component A1 is preferably 50 to 200 mgKOH / g. By setting the acid value to 50 mgKOH / g or more, the solubility of the unexposed area in the developer does not decrease, and by setting the acid value to 200 mgKOH / g or less, the development allowable width can be widened. Since component A1 has a low thermal decomposition temperature during firing, a copolymer containing acrylic acid ester, methacrylic acid ester, acrylic acid, and methacrylic acid as a copolymerization component is preferably used. The weight average molecular weight of component A1 becomes like this. Preferably it is 10,000-50000, More preferably, it is 15000-35000, More preferably, it is 20000-30000. 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 addition, the weight average molecular weight in this invention is measured using GPC. Tetrahydrofuran is used as the mobile phase, Shodex KF-803 is used as the column, and the weight average molecular weight can be calculated in terms of polystyrene.

  The content of Component A1 is preferably 10 to 80% by weight in the photosensitive organic component. If it is in the said numerical range, pattern formation property and the burning property at the time of baking can be made compatible.

  Component A2 is used to more effectively perform pattern formation with light. The molecular structure of component A2 is not limited in any way, such as linear, branched, cyclic, or combinations thereof, but is preferably linear from the viewpoint of compatibility. The weight average molecular weight of component A2 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.

  Specific examples of the ethylenically unsaturated group of Component A2 in the present invention 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, Dipentaerythritol hexaacrylate, dipentaerythritol monohydroxypentaacrylate, ditrimethylolpropane tetraacrylate, trimethylolpropane triacrylate, diacrylate of bisphenol A-propylene oxide adduct and some or all of these acrylates were replaced with methacrylate Examples include, but are not limited to.

  Component A2 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. By using such a compound as a photoreactive component, the compatibility of the photosensitive organic component can be improved and the photolithographic processability can be improved. As ethylene oxide content in component A2, 8-70 weight% is preferable with respect to component A2. Among such compounds, a compound containing ethylene oxide and propylene oxide is particularly preferable because of good burn-off.

  The content of Component A2 is preferably 10 to 80% by weight in the photosensitive organic component. If it is in the said numerical range, pattern formation property and the burning property at the time of baking can be made compatible.

  The compatibility of the photosensitive organic component can be evaluated by a haze value (cloudiness value). The haze value of the photosensitive organic component is obtained by measuring the haze meter after applying the photosensitive organic component to a glass substrate and drying it. The coating film thickness at this time is 100 μm. The photosensitive organic component used in the present invention preferably has a haze value of 10 or less. Within the above range, the compatibility is good and the light transmittance is high, so that photolithography can be effectively performed.

  Since component A1 and component A2 contained in the photosensitive organic component generally have a low ability to absorb actinic light energy, it is preferable to add a photopolymerization initiator in order to initiate a photoreaction. 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. One or more photopolymerization initiators and sensitizers can be used. The photopolymerization initiator is preferably contained in the range of 0.05 to 10% by weight, more preferably 0.1 to 10% by weight, based on the photosensitive organic component. By setting the content of the photopolymerization initiator within this range, good photosensitivity can be obtained while maintaining the remaining ratio of the exposed portion.

  In the present invention, a thermal polymerization initiator is an essential component. The sheet to which the thermal polymerization initiator is added can uniformly cure the entire sheet by a short heat treatment after the pattern processing step. The thermal polymerization initiator is essentially unnecessary for photolithography, and in particular, in the solvent drying and removal step after film formation using the photosensitive ceramic composition, the sheet is formed before the pattern processing step by heat due to drying. May be cured. Therefore, the 10-hour half-life temperature of the thermal polymerization initiator used in the present invention is preferably higher than the solvent drying removal temperature of the sheet. In other words, it is preferable to use a thermal polymerization initiator that does not start the reaction in the sheet drying step. If such a thermal polymerization initiator is used, the sheet is not cured before the pattern processing step, so that the pattern processability can be maintained. In addition, a sheet free from warpage or distortion can be obtained in the baking step after patterning. Since the drying temperature varies depending on the solvent used, an appropriate thermal polymerization initiator can be selected according to the solvent used and the drying temperature set at that time.

  The 10-hour half-life temperature is a temperature at which the thermal polymerization initiator decreases to half of the initial value after 10 hours due to thermal decomposition. The half-life was measured as follows. A thermal polymerization initiator solution is prepared using an inert solvent for the radicals of the thermal polymerization initiator, and sealed in a glass tube subjected to nitrogen substitution. This is immersed in a constant temperature layer set at a predetermined temperature for 10 hours and thermally decomposed, and the amount of the remaining thermal polymerization initiator is measured. A series of these operations was performed at several temperatures, and the half-life was obtained from the straight line obtained by plotting.

  The activation energy for primary radical formation of the thermal polymerization initiator suitably used in the present invention is preferably 120 to 180 kJ / mol. More preferably, it is 140-180 kJ / mol. When the activation energy is within the range of 120 to 180 kJ / mol, it is preferable because the sheet can be heat-treated after pattern processing in a short time without being cured when the sheet is dried by solvent.

  The thermal polymerization initiator of the present invention can be suitably used regardless of the azo-based / peroxide-based structure. For example, in azo series, 2,2'-azobis (2-methylpropionitrile), 2,2'azobis (2-methylbutyronitrile), 1,1'-azobis (cyclohexane-1-carbonitrile), 1-[(1-Cyano-1-methylethyl) azo] formamide (2- (carbamoylazo) isobutyronitrile), 2,2'-azobis {2-methyl-N- [2- (1-hydroxybutyl) ] -Propionamide}, 2,2′-azobis [2-methyl-N- (2-hydroxyethyl) -propionamide], 2,2′-azobis [N- (2-propenyl) -2-methylpropionamide ], 2,2'-azobis (N-butyl-2-methylpropionamide), 2,2'-azobis (N-cyclohexyl-2-methylpropionamide), 2,2'-azobis (2,4,4 -Trimethylpentane) (azodi-t-octane) and the like, and in the peroxide system, t-butylperoxypivalate, t-hexylperoxy-2-ethyl Ruhexanoate, 1,1-bis (t-butylperoxy) 2-methylcyclohexane, 1,1-bis (t-hexylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (t-hexyl) Peroxy) cyclohexane, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (t-butylperoxy) cyclohexane, 2,2-bis (4,4 -Dibutylperoxycyclohexyl) propane, 1,1-bis (t-butylperoxy) cyclododecane, t-hexylperoxyisopropyl monocarbonate, t-butylperoxymaleic acid, t-butylperoxy-3,5, 5-trimethylhexanoate, t-butylperoxylaurate, 2,5-dimethyl-2,5-di (m-toluoylperoxy) hexane, t-butylperoxyisopropyl monocarbonate, t-butylperoxy -2-ethylhexyl Carbonate, t-hexylperoxybenzoate, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, t-butylperoxyacetate, 2,2-bis (t-butylperoxy) butane, t -Butylperoxybenzoate, n-butyl-4,4-bis (t-butylperoxy) valerate, di-t-butylperoxyisophthalate, α, α'bis (t-butylperoxy) diisopropylbenzene, dibutyl Examples include, but are not limited to, milperoxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, and tert-butylcumyl peroxide.

  The content of the thermal polymerization initiator of the present invention is preferably 0.5 to 10.0% by weight with respect to the photosensitive organic component. More preferably, it is 1.0 to 5.0% by weight. If it is in the said range, the pattern workability of a sheet | seat can be maintained and the whole sheet | seat can be hardened uniformly at the time of heat processing.

  The content of the photosensitive organic component in the photosensitive ceramic composition is preferably 10 to 40% by weight, more preferably 15 to 35% by weight. If it is in the said range, the characteristic of both the flexibility and air permeability of a green sheet can be satisfied.

  The photosensitive ceramic composition used in the present invention contains 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 700 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 five 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, inorganic powder used as a low-temperature sintered ceramic material, such as anorthite (CaO—Al ₂ O ₃ −2SiO ₂ ), serdian (BaO—Al ₂ O ₃ −2SiO ₂ ), etc. 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 dissolve in the borosilicate glass. Further, spherical silica is preferable because the slurry can be filled more easily.

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

A fourth aspect of the above, _SiO on an oxide basis notation 2: 30-70 _{wt%, Al} 2 O 3: _5~40 wt%, CaO: 3 to 25 _{wt%, B} 2 O 3: _3~50 wt 30 to 60% by weight of a glass powder having a total amount of 85% by weight or more in a composition range of 50% by weight, alumina, zirconia, magnesia, beryllia, mullite, cordierite, spinel, forsterite, anorthite, serzian, silica and It is a mixture with 40 to 70% by weight of at least one kind of ceramic powder selected from the group of aluminum nitride.

A fifth aspect of the above, _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~ It is an inorganic powder contained in a proportion of 5% by weight.

  The inorganic powder can contain a filler component, and ceramic powder is often used as the filler component as described above, which is effective for improving the mechanical strength of the substrate and controlling the thermal expansion coefficient. 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.

Components such as SiO ₂ , Al ₂ O ₃ , CaO and B ₂ O ₃ in the glass powder are preferably 85% by weight or more in the total amount in the glass powder. The remaining less than 15% by weight can contain Na ₂ O, K ₂ O, BaO, PbO, Fe ₂ O ₃ , Mn oxide, Cr oxide, NiO, Co oxide and the like.

  In order to maintain the pattern forming property at a high level in the photosensitive ceramic composition, it is necessary to match the refractive indexes of the inorganic powder and the photosensitive organic component. The refractive index of the inorganic powder can be controlled by the blending ratio of the composition, and it is preferable to consider so as to match the average refractive index of the photosensitive organic component to be blended. It is preferable to match so that | N1-N2 | <0.15, where N1 is the refractive index of the inorganic powder and N2 is the refractive index of the photosensitive organic component.

  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 ceramic composition preferably used in the present invention and the method for producing the photosensitive ceramic sheet are 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 homogeneously mixed and dispersed with a kneader such as a ball mill to produce a slurry or paste of the photosensitive ceramic 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 1 to 5 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, and the like, and organic solvent mixtures containing one or more of them are used. The amount of the 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, in the paste (excluding inorganic powder) It is preferable that it is contained in 10 to 30% by weight.

  The obtained paste is formed on a support such as polyester by a general method such as a doctor blade method or an extrusion molding method, and the solvent is removed by drying, whereby the support and the photosensitive ceramic composition are formed. A sheet with a support in which ceramic sheets are laminated is obtained. The thickness of the photosensitive ceramic sheet is preferably 0.05 to 0.5 mm. As described above, it is necessary that the solvent is removed at a temperature lower than the 10-hour half-life temperature of the thermal polymerization initiator used in the present invention. Preferably, drying is performed at a temperature 5 ° C. or more, more preferably 10 ° C. or more lower than the 10-hour half-life temperature of the thermal polymerization initiator used. By drying at a temperature lower than the 10-hour half-life temperature of the thermal polymerization initiator, it is possible to prevent the sheet from being crosslinked before pattern processing, so that pattern processability can be maintained. In the subsequent development step, the solvent content of the photosensitive ceramic sheet is preferably 10% by weight or less. Therefore, in the step of removing the solvent by drying, the residual solvent amount should be 10% by weight or less. Is preferred.

  In general, a carrier tape such as polyethylene terephthalate, polyphenylene sulfide, or polypropylene is preferably used as the material for the support.

The thus obtained sheet with support is subjected to pattern exposure through a photomask having a via hole forming pattern, and via holes are formed by a pattern processing step of developing with a developer. The light source used for pattern exposure is particularly preferably an ultra-high pressure mercury lamp, but is not necessarily limited thereto. Although the exposure conditions vary depending on the thickness of the photosensitive ceramic sheet, it is preferable to perform the exposure for 5 seconds to 30 minutes if it is an ultrahigh pressure mercury lamp with an output of 5 to 100 mW / cm ² . In addition, the alignment guide hole at the time of sheet | seat lamination | stacking can be formed with the same method as the via hole formation.

  When the polymer which has a carboxyl group in a side chain is contained as a photosensitive organic component of the photosensitive ceramic sheet, it can be developed with an alkaline aqueous solution, which 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. It is desirable that the adhesiveness between the photosensitive ceramic sheet and the support is strong during development. This is to prevent the adhesiveness between the sheet and the support from being lowered, particularly when the development time is long, and being easily peeled off during development.

  In this manner, a sheet having a thickness before firing of 10 to 500 μm, a close-packed via hole pattern portion having a via hole diameter of 20 to 200 μm, and a via hole pitch of 30 to 250 μm can be produced. If necessary, the developed photosensitive ceramic sheet may be filled with a via hole or formed with a wiring by using a conductor, a resistor paste, or the like.

  Next, the patterned photosensitive ceramic sheet is peeled from the support. In this invention, it is preferable to heat-process prior to a peeling process. By performing the heat treatment, since the crosslinking of the photosensitive ceramic sheet further proceeds, the adhesiveness of the photosensitive ceramic sheet can be reduced and the peeling from the support can be facilitated.

  The heat treatment temperature of the sheet varies depending on the type of thermal polymerization initiator in the photosensitive ceramic sheet, but is performed at a temperature at which the thermal polymerization initiator can sufficiently react in a short time. The heat treatment temperature is preferably 180 ° C. or lower. More preferably, it is 150 degrees C or less. By setting the heat treatment temperature to 180 ° C. or less, thermal decomposition of the photosensitive ceramic sheet can be prevented. The sheet heat treatment time is not necessarily limited by the type of heat polymerization initiator and the heat treatment temperature, but is preferably 3 to 30 minutes. If it is shorter than that, the effect of the heat treatment may not be obtained. Further, if the heat treatment time is long, the process time is proportionally increased and the energy consumption increases, which is not preferable. By adding a thermal polymerization initiator, the heat treatment time can be significantly shortened.

  Such heat treatment to the photosensitive ceramic sheet can suppress warpage of the sheet after firing and suppress peeling of the laminate in the sheet firing step described in the next section. This is presumably because the heat treatment further promotes the reaction of unreacted organic matter in the sheet, reduces the unevenness of thermal stress during firing in the entire sheet, and suppresses the warpage of the sheet.

  Furthermore, the heat treatment has an effect of improving the solvent resistance of the photosensitive ceramic sheet. In particular, when a pattern is formed on the back surface of the sheet using a conductor or resistor paste after the ceramic sheet is peeled off, if the heat treatment is performed, the sheet is subject to erosion from the solvent contained in the conductor paste. It becomes difficult.

  The photosensitive ceramic sheet of the present invention is processed into a circuit board through a firing process. For example, a photosensitive ceramic sheet having a necessary number of wiring patterns formed thereon is stacked using guide holes and bonded at a temperature of 80 to 150 ° C. and a pressure of 5 to 25 MPa to produce a multilayer sheet. A hard-to-sinter ceramic sheet 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 ceramic composition, but firing is performed in air, in a nitrogen atmosphere, or in a hydrogen reduction atmosphere. In the firing of the photosensitive ceramic composition preferably used in the present invention, first, a step of decomposing and scattering an organic substance at room temperature to 600 ° C. (debinding step) is performed, and then sintering is performed at a temperature of 600 to 950 ° C. The ceramic multilayer substrate thus obtained is used as a high-frequency circuit substrate.

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

A. Photosensitive organic component monomer I (component A2): polyethylene glycol diacrylate (“M-245” manufactured by Toagosei Co., Ltd.)
Monomer II (component A2): urethane acrylate (“UV6100B” manufactured by Nippon Synthetic Chemical Industry Co., Ltd.)
Polymer I: A polymer obtained by adding 0.4 equivalent of glycidyl methacrylate to the carboxyl group of a copolymer composed of 30% styrene, 30% methyl methacrylate and 40% methacrylic acid (component A1). A solution of styrene, methyl methacrylate, methacrylic acid, and azoisobutyronitrile dissolved in a solvent “Solfit” kept at 75 ° C. is slowly added dropwise. After 5 hours of reaction, glycidyl methacrylate, tetrabutylammonium chloride, p-methoxy A solution in which phenol was dissolved was slowly dropped and reacted for 3 hours. Weight average molecular weight 30000, acid value 110
Polymer II: A copolymer obtained by adding 0.4 equivalent of glycidyl methacrylate to the carboxyl group of a copolymer consisting of 35% ethyl acrylate, 35% 2-ethylhexyl acrylate and 30% methacrylic acid (component A1). The copolymer was synthesized in exactly the same way except that styrene, methyl methacrylate, and methacrylic acid in Polymer I were replaced with 35% ethyl acrylate, 35% 2-ethylhexyl acrylate, and 30% methyl methacrylic acid. , Tetrabutylammonium chloride and p-methoxyphenol were added dropwise and reacted for 3 hours. Weight average molecular weight 25000, acid value 160
Photopolymerization initiator I: 2-benzyl-dimethylamino-1- (4-monoforinophenyl) -butanone-1 (“Irgacure 369” manufactured by Ciba Specialty Chemicals)
Thermal polymerization initiator I: 1,1′-azobis (cyclohexane-1-carbonitrile), activation energy 149.0 kJ / mol, 10 hour half-life temperature 88 ° C.
Thermal polymerization initiator II: t-ethylperoxy-2-ethylhexanoate, activation energy 120.6 kJ / mol, 10 hour half-life temperature 72 ° C.
Thermal polymerization initiator III: t-butyl peroxyacetate, activation energy 149.0 kJ / mol, 10 hour half-life temperature 102 ° C.
Thermal polymerization initiator IV: t-butylcumyl peroxide, activation energy 173.3 kJ / mol, 10 hour half-life temperature 119.5 ° C.
Thermal polymerization initiator V: t-hexylperoxy-2-ethylhexanoate, activation energy 118.1 kJ / mol, 10 hour half-life temperature 69.9 ° C.
UV light absorber: Sudan IV (manufactured by Tokyo Chemical Industry Co., Ltd.)
Polymerization inhibitor: p-methoxyphenol (Wako Pure Chemical Industries, Ltd.)
Solvent: “Solfit” (Kuraray Co., Ltd.)
Conductive paste: “H-4767” (manufactured by Shoei Chemical Industry Co., Ltd.).

B. Inorganic powder Inorganic powder I: Composite ceramics of alumina powder 55% + glass powder 45% Characteristics of alumina powder: Average particle diameter 2 μm
Composition of the glass powder: 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%)
Properties of the above glass powder: glass transition point 565 ° C., thermal expansion coefficient 60.5 × 10 ⁻⁷ / K, dielectric constant 8.0 (1 MHz), average particle diameter 2 μm
Inorganic powder II: Composite ceramics of 50% alumina powder + 50% glass powder Characteristics of the above-mentioned alumina powder: average particle size 37 nm
Composition of the glass powder: 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%)
Properties of the above glass powder: glass transition point 565 ° C., thermal expansion coefficient 60.5 × 10 ⁻⁷ / K, dielectric constant 8.0 (1 MHz), average particle diameter 2 μm
Inorganic powder III: Glass ceramic composite powder ("MLS-22" manufactured by Nippon Electric Glass Co., Ltd.)
Composition of the _{powder: SiO 2 -CaO-Al 2 O} 3 based ceramic composite above powder properties: Glass transition point 700 ° C., thermal expansion coefficient of 54 × ¹⁰ -7 / K, a dielectric constant 7.6 (15 GHz), the average particle Diameter 2.4μm
Inorganic powder IV: Composite ceramic of 85% Al ₂ O ₃ —SiO ₂ —B ₂ O ₃ glass powder + 15% quartz Composition of the glass powder: Al ₂ O ₃ (1.87%), SiO ₂ (67. 3%), K ₂ O (1.22%), B ₂ O ₃ (11.8%),
Properties of the above glass powder: glass transition point 507 ° C., thermal expansion coefficient 46 × 10 ⁻⁷ / K, dielectric constant 4.6 (1 MHz), average particle diameter 2.2 μm
Inorganic powder V: Al ₂ O ₃ —SiO ₂ —B ₂ O ₃ glass powder Composition of the above glass powder: Al ₂ O ₃ (0.34%), SiO ₂ (84.3%), K ₂ O (1 .29%), B ₂ O ₃ (11.7%),
Characteristics of the glass powder: glass transition point 509 ° C., thermal expansion coefficient 22 × 10 ⁻⁷ / K, dielectric constant 4.5 (1 MHz), average particle diameter 2.5 μm.
Inorganic powder VI: Glass ceramic composite powder ("MLS-25M" manufactured by Nippon Electric Glass Co., Ltd.)
Composition of the above powder: Al ₂ O ₃ —SiO ₂ —B ₂ O ₃ type powder Characteristics of the above glass powder: glass transition point 500 ° C., thermal expansion coefficient 42 × 10 ⁻⁷ / K, dielectric constant 4.7 (1 MHz) , Average particle size 3μm
Inorganic powder VII: Glass ceramic composite powder ("MLS-62" manufactured by Nippon Electric Glass Co., Ltd.)
Composition of the above powder: TiO ₂ —CaO—SiO ₂ -based powder Composition of the above glass powder: glass transition point 720 ° C., thermal expansion coefficient 81 × 10 ⁻⁷ / K, dielectric constant 8.5 (1 MHz), average particle diameter 1 .8μm
C. Developer Developer I: Tetramethylammonium hydroxide 0.25% aqueous solution Preparation of organic vehicle The solvent and polymer were mixed and heated to 60 ° C. with stirring to dissolve all the polymer. The solution was cooled to room temperature, and a monomer and a photopolymerization initiator were added and dissolved. The solution was vacuum degassed and then filtered through a 250 mesh filter to produce an organic vehicle.

E. Paste preparation Inorganic powder was mixed with the above organic vehicle, and wet mixed with a ball mill for 20 hours to form a slurry or paste. The amount of the inorganic powder was 75 parts by weight with respect to 25 parts by weight of the photosensitive organic components in the organic vehicle.

F. Production of photosensitive ceramic sheet A photosensitive ceramic sheet was produced by a doctor blade method at a molding speed of 0.2 m / min with a spacing of 0.1 to 0.8 mm between a polyester support and a blade in a room where ultraviolet rays were blocked. . The photosensitive ceramic sheet laminated on the support was dried at a predetermined temperature for a predetermined time to evaporate the solvent, and then cut into 126 mm squares. The thickness of the photosensitive ceramic sheet was 100 μm.

G. Formation of via hole Using a chromium mask with a via diameter of 80 to 150 μm and a via hole pitch of 500 μm, using a super high pressure mercury lamp with an output of 15 to 25 mW / cm ² from the upper surface of the sheet with the support, the sheet with the support and the mask A pattern exposure was performed by irradiating with 250 mJ / cm ² of ultraviolet rays under close contact conditions. Next, it developed with the developing solution hold | maintained at 25 degreeC, Then, the via hole was washed with water using the spray.

H. Heat treatment A photosensitive ceramic sheet with a support having a side length of 126 mm square was placed in an oven adjusted to an arbitrary temperature and heat-treated for a predetermined time. Thereafter, the photosensitive ceramic sheet was peeled from the support.

I. Formation of Conductor Circuit A conductor circuit was formed on the back surface of the peeled sheet by screen printing using a conductor paste “H-4767”.

J. et al. Lamination firing 5 to 6 photosensitive ceramic sheets were laminated and thermocompression bonded at 90 ° C. and a press pressure of 15 MPa. The obtained multilayer body was baked in air at a temperature of 900 ° C. for 30 minutes to produce a multilayer substrate.

K. Sheet warpage measurement The fired sheet was placed on a horizontal base, and the amount of warpage was determined by measuring the maximum amount of warpage from a flat surface.

Example 1
Inorganic powder I (75 parts by weight) as the inorganic powder, Polymer I (15 parts by weight), Monomer I (6 parts by weight), Monomer II (1.5 parts by weight) and photopolymerization initiator ( 2 parts by weight), thermal polymerization initiator I (0.5 parts by weight), ultraviolet light absorber (0.05 parts by weight), polymerization inhibitor (0.18 parts by weight), and after removing the film, the solvent is removed by drying. It dried at the temperature of 78 degreeC, and obtained the 100-micrometer-thick photosensitive ceramic sheet with a support body. After forming the via hole through the exposure and development process, heat treatment was performed at 120 ° C. for 10 minutes. The minimum via diameter that can be patterned was 80 μm. When the sheet was peeled from the support, it could be peeled without deformation to the sheet. Moreover, although the conductor circuit was screen-printed on the back surface of the sheet after peeling, erosion of the sheet from the conductor paste was not particularly observed. As a result of laminating and firing, there was no warping of the sheet after firing, and no peeling of the laminate was observed.

Examples 2-19
The procedure of Example 1 was repeated using the components shown in Table 1. The results are shown in Table 1.

Comparative Example 1
As shown in Table 1, a photosensitive ceramic sheet with a support was produced using the same components as in Example 1 except that no thermal polymerization initiator was added. After forming the via hole through the exposure and development process, heat treatment was performed at 120 ° C. for 10 minutes. The minimum via diameter that can be patterned was 80 μm. When the sheet was peeled from the support, the sheet was deformed during peeling. Moreover, when the conductor circuit was screen-printed on the back surface of the peeled sheet, erosion of the sheet from the conductor paste was observed. As a result of laminating and firing, the amount of warpage of the sheet was 6 mm, and the laminate was easily peeled off.

Comparative Example 2
As shown in Table 1, a photosensitive ceramic sheet with a support was produced using the same components as in Example 1 except that no thermal polymerization initiator was added. After forming the via hole through the exposure and development process, heat treatment was performed at 120 ° C. for 60 minutes. When the sheet was peeled from the support, it could be peeled without deformation to the sheet. Further, when a conductor circuit was screen-printed on the back surface of the peeled sheet, no erosion from the conductor paste was observed. As a result of laminating and firing, the amount of warpage of the sheet was 3 mm, but no peeling of the laminate was observed.

Claims (4)

A photosensitive ceramic composition comprising a photosensitive organic component, an inorganic powder, and a thermal polymerization initiator. The photosensitive ceramic sheet obtained by apply | coating the photosensitive ceramic composition of Claim 1 on a support body, and drying. The photosensitive ceramic sheet according to claim 2, wherein the 10-hour half-life temperature of the thermal polymerization initiator is higher than the drying temperature. A method for producing a photosensitive ceramic sheet by applying the photosensitive ceramic composition according to claim 1 on a support and then drying the coating, wherein the thermal polymerization initiator contained in the photosensitive ceramic composition is reduced to 10 hours by half. A method for producing a photosensitive ceramic sheet, wherein an initial temperature is higher than the drying temperature.