JPS6222201B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an insulating paste composition for forming an insulating ceramic thin layer by firing, which can be patterned by so-called photolithography. The insulating paste of the present invention has a wide variety of uses due to its excellent functions and effects, but for the convenience of making the explanation more specific and detailed, the following explanation will be given using a multilayer ceramic substrate in the electronics field as an example. Since multilayer ceramic substrates are the main application of the insulating paste composition according to the present invention, and their technical requirements are detailed and severe, we thought it would be a good opportunity to help people understand the advantages of the present invention. be. Therefore, the application of the present invention is not limited to multilayer ceramic substrates. Now, in today's electronics field, various devices such as integrated circuits, resistors, capacitors, inductances, etc. are mounted to construct desired circuits.
So-called circuit boards are frequently used instead of electrical wire connections. In order to meet the demand for increased packaging density, circuit boards have evolved from conventional single-layer wiring to multi-layer wiring. The first circuit board that was widely put into practical use was the so-called printed circuit board. The most typical method is to prepare a copper-clad laminate, and remove unnecessary portions of the copper layer by etching away with an etching solution to form desired copper wiring. Most of the copper used was removed, making resource use extremely inefficient, but at this point there was nothing that could be done about it, and it was at this stage that it was more meaningful to actually make something. . Laminated boards include phenolic resin, composite materials of paper and phenolic resin, composite materials of glass and epoxy resin, polyester resin,
etc. were frequently used. The etching mask used was a film printed with etching-resistant printing ink. Since this printing method using etching-resistant printing ink has limitations in forming fine patterns, it has recently been replaced by photolithography using etching-resistant photoresists. However, as can be seen from the material of the laminate, such printed circuit boards are insufficient in terms of heat resistance, electrical insulation, etc. In order to improve this point, so-called ceramic substrates have been developed that use plates of alumina, zirconia, magnesia, forsterite, etc. in place of the above-mentioned laminate plates. In this case, the wiring layer is covered with copper like the printed circuit board above →
Of course, it is possible to form it by etching, but if the copper foil is attached with a resin adhesive as in the past, there is no point in replacing it with a ceramic substrate, and soldering is also the same. No improvement will be made in terms of resource utilization efficiency. Therefore, I changed my thinking as follows. In other words, in the above-mentioned printed circuit board, the copper foil was initially patterned and an etching mask for etching away the copper foil was patterned by printing to form the desired copper wiring. The idea was to print a pattern from the beginning and avoid placing copper in unnecessary areas. A printing ink (hereinafter referred to as a conductive paste composition) is prepared by kneading fine powder of a conductor or a conductor compound, and a desired wiring pattern is printed on the surface of a ceramic substrate to maximize the high temperature resistance of the ceramic substrate. The idea is to burn in the wiring pattern. This is the so-called single-layer wiring ceramic substrate that is currently widely used. It is quite difficult to use copper as a conductor, and gold, platinum, palladium, or an alloy of silver and palladium are usually used. Now, the so-called conductive paste composition that has been put into practical use is just a printing ink, and its patterning has been done by so-called printing techniques such as screen printing. However, printing technology has difficulties in making patterns finer and more precise. Therefore, the idea arose of using a photosensitive resin such as the photoresist mentioned above as the vehicle component of the conductive paste composition and patterning it using the so-called photolithography technique. Conductive paste compositions completed based on this idea include those that use polyisoprene as the photosensitive resin component and xylene as the solvent, and those that use naphthalene-2.1- as the photosensitive resin component.
Diazo oxide sodium sulfonate (naphthalene-2,1-diazo-oxide sodium
The British patent No.
The invention described in Publication No. 1256344 is known. Thus, the above-mentioned ceramic substrate technology with single-layer wiring was completed, but since it was a single-layer wiring, it was natural that there was a limit to its packaging density, and a demand for multilayer wiring was raised. In order to meet this requirement, it is necessary to separate and insulate each conductor wiring layer, form through holes only in specific locations, and fill these through holes with conductors to make electrical connections. This led to research and development into formation technology and lamination technology. This technology has also developed through a development process similar to the above-mentioned conductor wiring layer forming technology, and the technology of patterning and firing a photopolymerizable insulating paste composition is finally about to be put into practical use. However, there are still various difficulties and things are not going as planned. The present invention is intended to solve these difficulties and to bring about the practical use of multilayer ceramic substrates. Whether it is a conductive paste composition or an insulating paste composition, the only difference is in the type of inorganic powder composition kneaded into it, whether it is a conductor constituent material or an insulating ceramic constituent material, and the idea is that the same vehicle composition can be used. There is a Japanese published patent No. 13591 in 1978.
The invention described in the publication is well known. Although this general idea is certainly true, practical research by the present inventors has revealed that there are still subtle differences, and that pursuing these characteristics requires different ingenuity. Most of the photopolymerizable insulation paste compositions currently in use consist of homopolymers of monomers represented by the following formula () or () or other copolymerizable monomers as organic polymer binders. A copolymer with is used.

【formula】

[Formula] (In the formula, R is hydrogen or a methyl group, R' is a C number of 1 to 12
(The alkyl group, R'' represents hydrogen, an alkyl group, or a haloalkyl group.) Of course, these homopolymers and copolymers can be used alone or as a mixture of two or more types. For example, these organic polymer conjugates are usually 50,000 ~
A molecular weight of about 1,000,000 is considered appropriate, and the viscosity of the paste composition is adjusted to about 15,000 to 60,000 centipoise. Since the insulating paste composition ultimately forms the desired insulating ceramic thin layer after firing, the vehicle component forms the insulating ceramic thin layer by reaction with the heat during firing or the atmosphere. We want it to disappear without damaging it. One of the major drawbacks of these conventional insulation paste compositions is their so-called poor smoothness. For example, an insulating paste composition is applied prior to forming a latent pattern image by light exposure, and good smoothness is also important here. Screen printing is convenient and often used when coating the entire surface of a substrate, but if the smoothness is poor, the screen mesh remains on the coating surface even after coating and is difficult to remove even if left for a long time. figure,
This is because sintering has to be carried out before sufficient surface smoothness is obtained. In this case, the mesh remains on the surface of the thin insulating ceramic layer after sintering. For example, when multi-layering wiring on a ceramic substrate, a conductive wiring layer is further laminated on the insulating ceramic thin layer, and another insulating ceramic thin layer is laminated on this conductive wiring layer. Since the thin layers are laminated alternately, even if the unevenness of the mesh is small individually, as the number of laminated layers increases, it will be amplified and cause disconnection of the conductor wiring layer, local resistance increase, or conversely. This may cause insulation failure or short circuit. Therefore, the level of smoothness of the insulating paste composition determines the limit of multilayering. However, conventional insulation paste compositions have poor smoothness, and in the case of the multilayer ceramic substrate mentioned above, the smoothness is poor.
The reality was that layer wiring was also difficult. Since an insulating paste composition must be kneaded with a large amount of fine inorganic powder composition, it has extremely high structural viscosity, and therefore it can be said that it naturally has poor smoothness. It is essential to find a means to improve the smoothness of such materials with extremely high structural viscosity while maintaining the high structural viscosity, and this was the greatest challenge faced by the present invention. Now, it has been believed by those skilled in the art to be effective as a solution to this problem, and the inventors of the present invention also believed that smoothness would improve if the surface tension was reduced. It was a thought. However, the conclusion was that this was a mistake. There are certainly many examples of success in improving smoothness by reducing surface tension. Therefore, it was common knowledge among those skilled in the art that the same thing as these precedents would also apply to insulating paste compositions, but this common sense was only valid in cases where the structural viscosity was relatively small. It is. For example, in the field of paints, silicone-based smoothing agents are often used to improve the smoothness of paint films, but adding surfactants to lower surface tension can more efficiently achieve a smooth coated surface. It would be advantageous if such a smoothing agent could be used to improve the poor smoothness of the insulating paste composition that is the object of the present invention. We have been conducting research in the direction of reducing this. However, these surface tension reducing agents are effective only when the paste itself has a low viscosity of 3,000 centipoise at most, and is useful for multi-layer lamination of insulating paste compositions for thick film technology with high viscosities of 15,000 to 60,000 centipoise. In the typical embodiment of the present invention, no effect was obtained. After experiencing numerous failures in this attempt to reduce surface tension, the inventors had an epiphany that previous attempts may have been an effort in the completely opposite direction. This is a shift in the idea that if you increase the surface tension and use this large surface tension to force the uneven surfaces of your own to attract each other, the surface will naturally become smooth. The insulating paste composition that is the subject of the present invention is often used using so-called thick film technology, and is often subjected to methods such as screen printing. Since the method itself becomes impracticable, we cannot afford to make the sacrifice of reducing structural viscosity in order to increase smoothness. Now, the inventors of the present invention have made such a change in their thinking.
The aim was to find a fundamental solution by increasing the surface tension by means other than adding additives. In other words, the idea was to provide the organic polymer bond itself with a large surface tension.
As a result of various trials and errors, they arrived at the present invention and successfully accomplished the task. By using the insulating paste composition of the present invention, it is possible to extremely easily multi-layer a ceramic substrate up to about five layers of wiring even if a very ordinary thick film technique is used at a publicly available technical level. When conventional insulating paste compositions are used, even if the technique used is extremely advanced and the construction is carefully performed by skilled workers, the
If we compare the limitations of layered wiring, we can clearly see that its industrial effects are outstanding. In addition, in these applications, an important requirement in combination with the above-mentioned smoothness is that the fired insulating ceramic thin layer has few voids and pinholes and is dense. It is much more severe for conductive paste compositions than for conductive paste compositions. This is because, for example, in the case of a conductor wiring layer, even if there are a large number of voids in it, if the conductor grains are in contact with each other somewhere around them, it is possible to perform a conductive function to some extent. This is because, in the case of voids in the insulating layer, they immediately appear as defects in electrical insulation. This density also has a significant influence on patterning performance as patterns become finer, which is also a matter of course. Previously, I have emphasized the effects of the present invention mainly on the basis of its smoothness, saying that the present invention makes it possible to easily realize five-layer wiring, but these various effects also naturally contribute. There is. The present invention significantly improves the smoothness of a polymer of ethylenically unsaturated compounds by introducing alcoholic hydroxyl groups, carboxyl groups, or both groups. That is, the insulating paste composition of the present invention contains an inorganic powder composition, an organic polymer binder, a photopolymerizable monomer, and a photopolymerization initiator, which will form an insulating ceramic upon firing. An insulating paste composition comprising: (1) one or more ethylenically unsaturated compounds as the minimum unit of polymerization as the organic polymer bond; (2) the minimum unit of polymerization constituting one polymer; When the total number of units is 100, the following specific group is 1
(3) the specific group is an alcoholic hydroxyl group or a carboxyl group; (4) the ethylenically unsaturated There are as many combinations between the type of compound and the type and number of the specific groups as there are combinations, and (5) the minimum unit of polymerization constituting one polymer is one or more of the combinations. An insulating paste composition using an organic polymer binder, characterized in that it simultaneously contains: There are many ethylenically unsaturated compounds that are advantageous for the present invention, and examples of them include the following. First, suitable ethylenically unsaturated compounds having an alcoholic hydroxyl group include, for example, hydroxyethyl acrylate, hydroxypropyl acrylate,
There are hydroxyalkyl acrylates represented by hydroxyethyl methacrylate and hydroxypropyl methacrylate, and methacrylates corresponding thereto. Also, favorable ethylenically unsaturated compounds with carboxyl groups include:
For example, acrylic acid, methacrylic acid, crotonic acid,
These include itaconic acid, maleic acid, fumaric acid, and maleic anhydride. Furthermore, examples of ethylenically unsaturated compounds having both an alcoholic hydroxyl group and a carboxyl group include vinyl oxycarboxylate compounds. Examples of ethylenically unsaturated compounds suitable for copolymerization with these ethylenically unsaturated compounds having an alcoholic hydroxyl group or carboxyl group include methyl methacrylate, ethyl methacrylate, butyl methacrylate, isobutyl methacrylate, lauryl methacrylate, and methyl methacrylate. In addition to methacrylates (acrylates) such as acrylate, ethyl acrylate, stearyl methacrylate, n-decyl methacrylate, dimethylamino methacrylate, 2-ethylhexyl methacrylate, isodecyl methacrylate, and diethylaminoethyl methacrylate, acrylonitrile, styrene, hydroxystyrene,
Vinyl acetate and the like are also convenient. Examples of the resulting copolymers include poly(methyl methacrylate/β-hydroxyethyl acrylate), poly(methyl methacrylate/β-hydroxypropyl acrylate), poly(methyl methacrylate/methacrylic acid/acrylic acid), and poly(methyl methacrylate/β-hydroxypropyl acrylate). (methyl methacrylate/n-butyl methacrylate/β-hydroxyethyl methacrylate),
Poly(isobutyl methacrylate/β-hydroxypropyl methacrylate), poly(isobutyl methacrylate/β-hydroxypropyl methacrylate/methacrylic acid), poly(methyl methacrylate/styrene/β-hydroxyethyl methacrylate), poly(styrene/maleic acid/β)
-hydroxybutyl methacrylate), poly(lauryl methacrylate/β-hydroxypropyl methacrylate/styrene), poly(methacrylate/vinyl acetate/β-hydroxyethyl acrylate), poly(methyl methacrylate/2-ethylhexyl methacrylate/β-hydroxyethyl acrylate) , poly(methyl methacrylate/ethyl acrylate/methacrylic acid), poly(methyl acrylate/glycidyl methacrylate/β-hydroxyethyl acrylate), poly(ethyl methacrylate/β-hydroxypropyl methacrylate), poly(methyl methacrylate/β-hydroxypropyl acrylate) / itaconic acid), poly(methyl methacrylate/dimethylamino methacrylate/methacrylic acid), poly(methyl acrylate/styrene/acrylic acid),
Poly(methyl methacrylate/vinyl acetate/β-
hydroxypropyl methacrylate), poly(methyl methacrylate/β-hydroxyethyl acrylate/methacrylic acid/ethyl acrylate), poly(methyl methacrylate/β-hydroxybutyl methacrylate/acrylic acid/styrene), poly(isobutyl methacrylate/β-hydroxyhexyl methacrylate) /acrylic acid), poly(styrene/acrylonitrile/methyl acrylate/methyl methacrylate/methacrylic acid), etc., and each has achieved good results. The present invention has been explained above using an example in which an ethylenically unsaturated compound having an alcoholic hydroxyl group, a carboxyl group, or both of these groups is prepared and copolymerized to produce the organic polymer conjugate of the present invention. There are many other methods for producing the organic polymer conjugate of the present invention. For example, it is of course possible to first form an organic polymer bond serving as a skeleton and then saponify or oxidize a portion of it. For example, you can saponify polyvinyl acetate and convert some of it into alcoholic hydroxyl groups, or copolymerize methyl methacrylate and vinyl acetate to form a polymer with a desired molecular weight, and then saponify this to convert a portion of it into alcoholic hydroxyl groups. It is also effective to convert it into an alcoholic hydroxyl group. A reaction in which an organic polymer conjugate having an aldehyde group is oxidized and converted into a carboxyl group is also convenient as a means for producing the organic polymer conjugate of the present invention. Furthermore, there is also a means of utilizing an addition reaction such as an addition reaction of maleic anhydride. Now, in the present invention, the reason why the total number of minimum polymerization units having one or more specific groups should be 2 to 85 when the total number of minimum polymerization units is 100 will be explained below. The main point of the present invention in order to solve the above-mentioned prior art is that an alcoholic hydroxyl group, a carboxyl group, or both groups are provided in the organic polymer bond, and these groups are newly incorporated. As explained in detail above, the introduction of this method into the wafer was extremely effective in improving smoothness. In other words, by introducing these groups, the polarity of the organic polymer bond increases and its surface tension increases, and as a result, even if the insulating paste composition inevitably becomes highly viscous, the surface of the coating film increases. This meant that the area was quickly smoothed out. However, it is natural that the ratio of alcoholic hydroxyl groups and carboxyl groups, which also have this smoothness improving effect, decreases as the composition approaches the conventional composition, and the lower limit at which the significant difference is lost was 2. . It is an experimental fact that if the problem faced by the present invention is only to improve smoothness, it would be better to introduce more of these groups. However, as this ratio increases, the polarity of the organic polymer bond becomes stronger, as mentioned above, and as a result, it tends to be soluble only in highly polar solvents. Although this may not seem to have much meaning at first glance, it is possible to develop a developing solution that can be used when developing an insulating paste composition that has been photopolymerized only in a specific area and dissolving and removing areas other than the desired pattern. This means that the types are limited to those with strong polarity, which is not desirable when considering industrial use. As the polarity becomes stronger, the range of conditions under which development can be performed becomes narrower and workability deteriorates. In this case, the solvent also tends to be highly volatile, which increases the danger of flames and makes it difficult to print, making it unsuitable for so-called thick film technology. As described above, as the number of alcoholic hydroxyl groups, carboxyl groups, or both of these groups increases, the polarity increases, but the smoothness becomes better and better. However, in addition to the above-mentioned polarity problem, as the number of these groups increases, the so-called retention ability of the inorganic powder composition in suspension tends to deteriorate as the insulating paste composition, so there is still an upper limit. should be considered. This upper limit is determined by the balance of the effects of different types, so it is not as clear as the lower limit, but it would be appropriate to set it at around 85. If you want to ensure that all of the above benefits are satisfied at the same time, 5
It is safe to set it to about 65, and in this case, significant effects were obtained in almost all combinations with inorganic powder compositions, photopolymerizable monomers, and photopolymerization initiators. When using an organic polymer conjugate having only an alcoholic hydroxyl group as a specific group, 5 to 25
To a certain extent, the phenomenon can be achieved using only a nonflammable solvent such as chlorocene (1,1,1-trichloroethane), and conventional thick film technology can be applied as is, which is more convenient. When using an organic polymer bond containing only a carboxyl group as a specific group, it is more convenient to set the number to about 6 to 55 because weak alkaline development can be performed. If it exceeds 55, it will not be soluble in ordinary solvents commonly used in thick film technology, so it is not very desirable. When using an organic polymer bond containing both an alcoholic hydroxyl group and a carboxyl group as the specific group, as the ratio of carboxyl groups increases, it tends to become more suitable for alkaline development. Although the features of the present invention have been explained above, the compositions of the present invention other than the organic polymer conjugate will be exemplified below. First, there is an inorganic powder composition, which is a material that forms insulating ceramic by firing. Therefore, the composition needs to be appropriately determined depending on which and how much of the various characteristics supporting the purpose of use are desired to be satisfied, and in fact there is a great degree of freedom in its selection.
Acidic, basic, and neutral refractories such as alumina, silica, magnesia, spinel, etc., as well as various inorganic oxides that are raw materials for obtaining them, and lead borosilicate glass. Zinc borosilicate glass, lead zinc borosilicate glass,
Glasses such as these can be used. Although the particle size of these inorganic powder compositions does not need to be particularly limited, it has been empirically determined that it is easier to handle if the particle size is adjusted to about 0.05 to 15 μm. As the photopolymerizable monomer, photopolymerizable ethylenically unsaturated compounds typified by polyfunctional acrylic monomers can be used. Allyl group, vinyl ether group,
Compounds with vinylamino groups can also be used. Suitable examples include polyethylene glycol diacrylates (n=2 to 200) represented by diethylene glycol diacrylate, triethylene glycol diacrylate, and tetraethylene glycol diacrylate, methacrylates corresponding thereto, and polyalkylene glycol diacrylates. Various acrylates represented by acrylates (n = 4 to 11), pentaerythritol triacrylate, trimethylolpropane triacrylate, and 2,2-dimethylpropane diacrylate, and their corresponding methacrylates are effective, It can also be used as a mixture of two or more of them. As photopolymerization initiators, benzophenones, vicinal ketones such as diacetyl, benzyl, α
- pyridine, acyloins such as benzoin, pivaloin, α-pyridoin, acyloin ethers such as benzoin methyl and ethyl ether;
α-Hydrocarbon-substituted aromatic acyloins such as α
- Methylbenzoyl, α-tert-butylbenzoin, acyloin esters such as benzoin acetate and benzoyl alkyl ethers, conjugated 6-membered carbon in which there is at least one aromatic carbocyclic ring fused to a ring containing a carbonyl group Substituted and unsubstituted quinones having two endocyclic carbonyl groups bonded to endocyclic carbon atoms in the cyclic ring, such as ethylanthraquinone, benzanthraquinone, diaminoanthraquinone, benzophenone and 4,4′-bis(dimethylamino)benzophenone, Examples include triphenylphosphine. These may be used alone or as a mixture of two or more. The amount of this photopolymerization initiator used may be small, and it is sufficient to use it in a range of usually 0.01 to 10% by weight, preferably 0.05 to 5% by weight, based on the total amount of the organic polymer bond. The insulating paste composition of the present invention thus obtained functions as an extremely excellent paste with high screen printing performance when used, for example, in thick film technology. This is largely due to the fact that it is extremely easy to adjust the viscosity to a value of about 2,000 to 500,000 centipoise as measured by a B-type rotational viscometer when the temperature is about 25°C. The molecular weight of the organic polymer conjugate used at this time is preferably about 15,000 to 600,000. If the insulating paste composition of the present invention is to be used effectively utilizing its characteristics as a photopolymerizable paste, the preferred viscosity range is 5,000 to 100,000 centipoise.
If it is less than 5,000 centipoise, a single coating film will be thin and uneconomical, and the smoothness will also deteriorate.
If it is 100,000 centipoise or more, printing becomes difficult. As the solvent used in the insulating paste composition of the present invention, those having a boiling point in the range of 140 to 300°C at atmospheric pressure can be used, but a preferable example is one having a boiling point in the range of 170 to 260°C as the main solvent. It is convenient to use A co-solvent may also be used. If the boiling point of the main solvent is below 170°C, drying will be too fast, which will have an adverse effect on the smoothness of the coating film, and will also dry the screen plate and cause clogging of the screen mesh.
If the temperature is 260°C or higher, it is good for smoothing, but the drying properties are poor and it is uneconomical, and sometimes photopolymerizability is impaired.
Suitable solvents that meet these various conditions include, for example, methyl carbitol, ethyl carbitol, butyl carbitol, methyl carbitol acetate, ethyl carbitol acetate,
High boiling points of butyl carbitol acetate, ethylene glycol monobutyl ether, ethylene glycol monoethyl ether acetate, methoxybutyl acetate, diacetone alcohol, isophorone diisobutyl ketone, ethylene glycol monobutyl ether acetate, pine oil, terpineol, 2-ethylhexyl acetate, etc. These include derivatives of polyhydric alcohols, ketones, esters, and terpenes. Hereinafter, from among the many embodiments of the present invention, some embodiments that are considered to be in relatively high demand will be selected and explained in detail. Example 1 850 parts by weight of methyl methacrylate, 150 parts by weight of β-hydroxyethyl acrylate, 15 parts by weight of azobisisobutyronitrile, and 1000 parts by weight of ethyl carbitol acetate were added to a condenser, a thermometer,
The mixture was placed in a 3-separable flask equipped with a stirrer. Next, the internal temperature was raised to 70℃ while stirring for 40 minutes using a mantle heater, and the temperature was raised to 70℃ while controlling the exothermic reaction.
Polymerization was carried out by stirring at ~75°C for 50 minutes. Next, upon cooling to room temperature, a transparent and viscous poly(methyl methacrylate/β-hydroxyethyl acrylate) was obtained. The viscosity of this methacrylic acid ester copolymer solution was 32,000 centiboads (25°C), and the average molecular weight of the copolymer was 141,000. 100 parts by weight of a 50% solution of poly(methyl methacrylate/β-hydroxyethyl acrylate (85/15) in ethyl carbitol acetate, 12 parts by weight of tetraethylene glycol diacrylate, 3 parts by weight of pentaerythritol triacrylate, tertiary butyl 2 parts by weight of anthraquinone, 75 parts by weight of fine alumina powder, 45 parts by weight of fine low-melting glass powder, 0.025 parts by weight of methylhydroquinone.
3 parts by weight, 0.5 parts by weight of antifoaming agent, 3 parts by weight of the above composition.
The mixture was kneaded using a roll mill. The viscosity was measured using a rotational viscometer and was found to be 39,000 centipoise. After printing this paste twice at a thickness of 25 μm on the entire surface of the alumina substrate on which the conductor circuit is formed using a 230 mesh stainless steel screen,
The coating film became smooth after 10 minutes. This was dried in a hot air dryer at 85°C for 30 minutes and left until it reached room temperature. Next, a latent image was formed by irradiating with an ultra-high pressure mercury lamp for 6 seconds through an exposure mask having a predetermined pattern, and then developed by spraying using chlorocene as a developer. The film thickness of the remaining portion was 48 μm. In addition, the through holes formed by removal by development had sufficiently satisfactory sharpness. This was fired at 900°C for 2 hours to obtain an insulating ceramic thin layer with the desired through holes.
The thickness of this insulating ceramic thin layer was 27 μm. In addition, the leakage current was measured in weak salt water as a measure of the degree of insulation of the thin insulating ceramic layer. The leakage current was 20μA at 5V DC, indicating excellent insulation. Example 2 Poly(methyl methacrylate/β-hydroxyethyl acrylate) similar to that used in Example 1
100 parts by weight of ethyl carbitol solution, 9 parts of polyethylene glycol diacrylate (n=14)
parts by weight, 3 parts by weight of diethylene glycol diacrylate, 4 parts by weight of trimethylolpropane triacrylate, 20 parts by weight of fine magnesia powder, and low melting point glass (GA-9 manufactured by Nippon Electric Glass).
85 parts by weight, 0.025 parts by weight of methylhydroquinone, 0.1 parts by weight of antifoaming agent, and ethyl violet.
0.3 parts by weight, 2 parts by weight of cellulose acetate,
When 2.5 parts by weight of ethyl anthraquinone was kneaded using three rolls, the viscosity was 19,500 centipoise. In the same way as in Example 1, a 30μm film was printed on an alumina substrate with a conductor formed thereon by screen printing.
After printing twice, it became smooth after 7 minutes. After that, it was exposed, developed and fired. The thickness of the insulating ceramic layer after firing was 30 μm, and a sharp image with through holes of 130 μm square was obtained. The leakage current was 22μA at 5V, indicating excellent insulation. Example 3 740 parts by weight of methyl methacrylate, 110 parts by weight of β-hydroxypropyl methacrylate, 150 parts by weight of methacrylic acid, 13 parts by weight of azobisisobutyronitrile, 650 parts by weight of butyl carbitol, ethylene glycol monoethyl 350 parts by weight of ether acetate was heated to 65° C. with stirring for 80 minutes using a mantle heater set in the same manner as in Example 1, and stirred and polymerized at a temperature of 65° C. to 70° C. for 40 minutes while cooling. The viscosity of this copolymer was 48,000 centipoise. The molecular weight was 98,000. 10 parts by weight of this reaction product, 0.8 parts by weight of tetraethylene glycol, 0.4 parts by weight of polyethylene glycol diacrylate (n=9), 0.6 parts by weight of pentaerythritol triacrylate,
44 parts by weight of mullite (Al ₂ O ₃・SiO ₂ ) fine powder, 1 part by weight of low melting point glass (GA-9), 0.4 part by weight of benzoin isopropyl ether, and 0.01 part by weight of Michler's ketone were kneaded in a three-roll mill. did. Next, print and coat onto the alumina substrate and after drying,
It was exposed to ultraviolet light through an exposure mask having a 150 μm square through-hole pattern. When developed with a 1.5% diethanolamine aqueous solution, the desired result was obtained.
A clear through-hole image of 150 μm square was obtained. Next, the temperature was raised to 990°C for 3 hours, held for 30 minutes, and fired, resulting in the desired homogeneous insulating ceramic thin layer with a smooth surface and sharp through holes. Example 4 Poly(methyl methacrylate/β-hydroxyethyl acrylate) similar to that used in Example 1
100% solution of ethyl carbitol acetate
parts by weight, 12 parts by weight of tetraethylene glycol diacrylate, 3 parts by weight of pentaerythritol triacrylate, 2 parts by weight of tert-butyl anthraquinone, 55 parts by weight of fine alumina powder,
_SiO2 , _{B2O3 , ZrO2} , ZnO, PbO, _Na2O , _K2O ,
65 parts by weight of fine powder of lead borosilicate crystallized glass containing MgO, CaO, and TiO ₂ and methylhydroquinone.
0.025 parts by weight of the antifoaming agent, 0.5 parts by weight of the antifoaming agent, and 0.5 parts by weight of Oil Blue #603 (manufactured by Orient Chemical Co., Ltd.) were kneaded in a three-roll mill to obtain a paste with a viscosity of 46,000 centipoise. This is screen printed onto an alumina substrate with a conductor circuit formed on it and dried.
When exposed and developed through an exposure mask with a 100 μm square through-hole pattern, a 100 μm square
An image with sharp through holes at the corners was obtained. After that, it was fired at 910°C, and a thin layer of insulating ceramic having a thickness of 30 μm and having the desired sharp through holes was obtained. After that, a leakage current test was conducted in the same manner as in Example 1, and the result was 20μ at 10V DC.
It showed very excellent insulation properties of A or less. Example 5 The same composition as Example 4 was used except for the inorganic powder composition, and the inorganic powder composition contained SiO ₂ ; 31% by weight,
_B2O3 ; _3.6 % by weight, PbO; 10% by weight, _Na2O ; 2.0
Weight%, CaO; 8.0% by weight, _ZrO2 ; 1.7% by weight,
A mixed fine powder containing 43.7% by weight of Al ₂ O ₃ was kneaded in a three-roll mill to form a paste. Thereafter, treatment was carried out in the same manner as in Example 4, and a smooth insulating ceramic thin layer with sharp through holes was obtained. Leakage current is 10μA at 10V DC
It showed very excellent insulation properties as shown below. As can be seen from the examples illustrated above, the effects of the present invention are outstanding. For reference with these embodiments of the present invention, some examples of how to obtain relatively good results from the prior art are as follows. First, 850 parts by weight of methyl methacrylate, n
-150 parts by weight of butyl methacrylate, 15 parts by weight of azobisisobutyronitrile, and 100 parts by weight of ethyl carbitol acetate were weighed, and these were placed in a three-separable flask equipped with a condenser, a thermometer, and a stirring device. This was reacted in the same manner as in Example 1. Obtained poly(methyl methacrylate/n-butal methacrylate (85/15))
The viscosity of the solution was 29,000 centipoise (25°C). An insulating paste composition was prepared in the same manner as in Example 1 using the organic polymer bond thus obtained. Although the composition of this insulating paste is exactly the same except for the organic polymer bond, when it was screen printed on an alumina substrate, a smooth coated surface was still not obtained even after 60 minutes had passed, and the screen The printing marks were still visible. A similar test was performed on poly(methyl methacrylate/
Ethyl acrylate (85/15)), poly(methyl methacrylate/lauryl methacrylate (90/
10)) and various organic polymer combinations of poly(n-butyl methacrylate/methyl acrylate (95/5)), but all of these could not provide a sufficiently smooth surface, so multilayering was not possible. It was difficult.

Claims (1)

[Scope of Claims] 1. An insulating paste made by kneading an inorganic powder composition, an organic polymer bond, a photopolymerizable monomer, and a photopolymerization initiator, which will form an insulating ceramic upon firing. A composition, wherein the organic polymer conjugate includes (1) one or more ethylenically unsaturated compounds as the minimum unit of polymerization, and (2) the total number of the minimum units of polymerization constituting one polymer. When 100, the following specific group is 1
(3) the specific group is an alcoholic hydroxyl group or a carboxyl group; (4) the ethylenically unsaturated There are as many combinations between the type of compound and the type and number of the specific groups as there are combinations, and (5) the minimum unit of polymerization constituting one polymer is one or more of the combinations. An insulating paste composition using an organic polymer binder, characterized in that it simultaneously contains: