JP2000284471A - Photosensitive paste - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a photosensitive paste which does not thicken and solidify and has excellent developability by incorporating a tetrazole derivative into the photosensitive paste essentially consisting of inorganic powder and photosensitive organic components. SOLUTION: The photosensitive paste essentially consisting of the inorganic powder and the photosensitive organic components is formulated to contain the tetrazole derivative. The photosensitive organic components are the organic components which consist essentially of an alkali soluble polymer, a multifunctional monomer having >=2 carbon-carbon double bonds in one molecule and bears a photosensitivity. The inorganic powder includes conductive powder and insulating powder. The conductive powder exhibits a particularly high effect when powder containing metals, such as copper, having high reactivity, and their oxides, is used as the conductive powder. The average particle size of the conductive powder is preferably in a range of 2 to 5 μm. The tetrazole derivative is preferably 1H-tetrazole. The amount. of the tetrazole derivative to be added is preferably 0.01 to 20 wt.% of the total weight.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a ceramic substrate,
The present invention relates to a photosensitive conductive paste for forming a conductive pattern on a glass substrate, a photosensitive glass and a ceramic paste for forming an insulating layer.

[0002]

2. Description of the Related Art In recent years, multi-chip modules mounted on personal computers and PC cards, chip-size packages,
In addition, demands for miniaturization, higher density, and higher reliability are increasing for electronic components such as filters for high frequencies, chip inductors, multilayer capacitors, and multilayer ceramic substrates for mobile communication devices such as mobile phones. In addition, as the definition of a display device such as a plasma display increases, the demand for miniaturization of electrodes and partition walls has also increased.
To meet these requirements, various fine film forming methods have been proposed.

Typical methods include a thin film method, a plating method, and a thick film printing method. In the thin film method, after forming a film by sputtering, evaporation, etc., the resolution L /
Although patterning of S = 20/20 μm or more is possible, in this method, the thickness of the conductor film is proportional to the time of sputtering or vapor deposition, and it takes a long time to increase the thickness, so that only a thin film can be obtained. As a result, there is a disadvantage that the impedance of the circuit is increased. Further, the plating method has a problem that it is difficult to form a thick-film passive element such as a resistor in a firing step.

On the other hand, in a thick film printing method in which a film is formed by screen printing, it is easy to simultaneously form passive elements such as a thicker conductor film and a resistor, but on the other hand, L / S
= It is difficult to form a line with a fixed width at a resolution of 50/50 µm or more, and there is a problem that the shape of the cross section is in a semi-cylindrical shape and it is difficult to design the electric characteristic surface.

In the case of forming a multilayer wiring layer on a ceramic substrate, as the wiring becomes finer, finer through holes for connecting the insulating layers are required. To form an insulating layer of glass, glass ceramics, ceramics, etc. on a ceramic substrate, there are a thick film printing method and a green sheet method, but it is difficult to form a fine through hole of 100 μm or less in any case. It is.

As a method for improving the resolution and the sectional shape of the thick film printing method, there is a photosensitive paste method. This uses a conductive paste for thick-film printing or a photosensitive paste as an insulating paste.After printing, the mask is exposed and developed to form high-resolution thick-film conductor patterns and through holes. What you get. The photosensitive conductive paste is a mixture of a conductive powder such as metal or carbon and a photocurable resin, and the photosensitive insulating paste is a mixture of an inorganic powder such as glass or ceramics mixed with a photocurable resin. Used.

Although the photosensitive paste method is an excellent method,
There is a problem that an acrylic copolymer often used as a photosensitive resin reacts with a certain kind of metal, causing an increase in viscosity and, in severe cases, solidification. The conductor powder is gold,
No reaction occurs when a chemically stable noble metal such as silver is used. However, this problem is remarkable in a base metal, particularly copper which is inexpensive and has a low electric resistance and is suitable as a wiring material.
In addition, glass and ceramic components contain a large amount of metal oxides, and depending on the type, problems of thickening and solidification similar to copper have occurred. To address this problem, there is a surface treatment method using benzotriazole, which is a general copper rust preventive (Japanese Patent Laid-Open No. 10-287821).

Further, the present invention can be applied to electronic parts such as a multichip module, a chip size package, a high frequency filter for a mobile communication device such as a mobile phone, a chip inductor, a multilayer capacitor and the like, a ceramic multilayer substrate, a plasma display and the like. Although different from electrodes and partition walls used for a display device, those using a tetrazole derivative contained in a polyimide resin used for an interlayer insulating film of a semiconductor (Japanese Patent Laid-Open No. 8-2863)
No. 74)

[0009]

However, since it is necessary to obtain more sufficient storage stability and also to obtain good resolution, it is therefore an object of the present invention to provide a method for producing a powder of copper, glass, ceramics or the like. An object of the present invention is to provide a photosensitive paste which does not thicken or solidify even when used, and is further excellent in developability.

[0010]

According to the present invention, there is provided a photosensitive paste containing a tetrazole derivative in a photosensitive paste containing an inorganic powder and a photosensitive organic component as essential components.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail, but the present invention is not limited thereto.

The present invention suppresses the reaction between the photosensitive resin and the inorganic powder in the photosensitive paste containing the photosensitive resin and the inorganic powder as essential components, prevents thickening and solidification, and obtains a stable photosensitive paste. It is something that can be done.

The photosensitive organic component used in the present invention includes:
An organic component responsible for photosensitivity in a photosensitive paste, containing an alkali-soluble polymer, a polyfunctional monomer having two or more carbon-carbon double bonds in one molecule, and a photopolymerization initiator as essential components. It is.

An acrylic copolymer is used as the alkali-soluble polymer. The acrylic copolymer is a copolymer containing at least an acrylic monomer in a copolymer component, and specific examples of the acrylic monomer 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-hydroxyethyl 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 Acrylic monomers such as acrylates, and those obtained by replacing these acrylates with methacrylates are exemplified. Desirably, by containing an alkyl acrylate or an alkyl methacrylate, more preferably at least methyl methacrylate, a polymer having good thermal decomposability can be obtained. As the copolymerization component other than the acrylic monomer, all compounds having a carbon-carbon double bond can be used, but preferably styrene, p-methylstyrene, o-methylstyrene, m-methylstyrene, α-methyl Styrenes such as styrene, chloromethylstyrene and hydroxymethylstyrene, γ-methacryloxypropyltrimethoxysilane, 1-vinyl-2-
And pyrrolidone.

Since the polymer has alkali solubility, the developer is not an organic solvent having environmental problems,
An alkaline aqueous solution can be used. In order to impart alkali solubility to the acrylic copolymer, it is achieved by adding an unsaturated acid such as an unsaturated carboxylic acid as a monomer. Specific examples of the unsaturated acid include acrylic acid, methacrylic acid, itaconic acid, crotonic acid, maleic acid, fumaric acid, vinyl acetate, and acid anhydrides thereof.

As the polyfunctional monomer, a compound having two or more carbon-carbon double bonds in one molecule is used, and specific examples thereof include allylated cyclohexyl diacrylate and 1,4-butanediol diacrylate. Acrylate,
1,3-butylene glycol diacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate,
Polyethylene glycol diacrylate, dipentaerythritol hexaacrylate, dipentaerythritol monohydroxypentaacrylate, ditrimethylolpropane tetraacrylate, glycerol diacrylate, methoxylated cyclohexyl diacrylate, neopentyl glycol diacrylate, propylene glycol diacrylate, polypropylene glycol diacrylate , Triglycerol diacrylate, trimethylolpropane triacrylate, bisphenol A
Examples of the present invention include diacrylate, diacrylate of bisphenol A-ethylene oxide adduct, diacrylate of bisphenol A-propylene oxide adduct, and compounds in which the acryl group of the above compound is replaced with one part or all of a methacryl group. It is not limited to these monomers.

The inorganic powder used in the present invention includes a conductive powder and an insulating powder, each of which will be described below.

The shape of the inorganic powder used in the present invention may be plate-like, scale-like, conical, angular, rod-like, granular, acicular, etc., but it should be monodisperse with little aggregation, spherical or granular. Is desirable. In this case, the spherical shape preferably has a sphericity of 80% by number or more. For the measurement of the spheroid ratio, the powder was photographed with an optical microscope at a magnification of 300 times and counted, and the ratio of spherical particles was expressed. When the particles are spherical, scattering of light during exposure is very small, and light is easily transmitted to the inside of the film.

The conductive powder used in the present invention includes carbon powder, metal powder and the like.
There are gold, silver, copper, nickel, tungsten, molybdenum, and the like. Although the present invention exerts a particularly great effect when a highly reactive metal such as copper or a powder containing an oxide thereof is used, the present invention is not limited to these types of metals. . The average particle size of the conductive powder is 2
It is desirable that the thickness be in the range of 5 μm to 5 μm. Average particle size is 2
If it is smaller than μm, when the same volume of conductive powder is added to the resin, the surface area of the powder becomes large, so that more light is blocked, and the light transmittance into the paste is reduced. If it is larger than 5 μm, the surface roughness when applied is large, and the pattern accuracy and dimensional accuracy are undesirably reduced.

The insulating powder used in the present invention includes ferrite, cordierite, forsterite, alumina, silica, mullite, cristobalite, corundum (α-alumina), zirconia, calcium oxide, magnesium oxide, chromium oxide, lithium oxide, Examples include lead oxide, boron oxide, iron oxide, zinc oxide, nickel oxide, and borosilicate glass, which are particularly effective in insulating powders containing lead oxide and calcium oxide, but are not limited thereto. Not something.

The average particle size of the insulating powder is preferably 0.5 to 7 μm from the viewpoint of dispersibility. If the average particle size is less than 0.5 μm, the dispersion in the paste is reduced,
If it is larger than 7 μm, the dimensional accuracy of the pattern and the surface roughness of the coated film surface are undesirably reduced. From the viewpoint of photolithography, a method in which scattering is small and a large amount of light passes through the film is preferable, and in that case, the thickness is preferably 1 μm or more. Taking these into consideration, the preferred average particle size of the insulating powder is 1 to 7 μm.

The tetrazole inducer used in the present invention includes 1H-tetrazole, 5,5'-bis-1H-
Tetrazole, 5-methyl-1H-tetrazole, 5-
5-substituted-1H-tetrazole such as phenyl-1H-tetrazole, 5-amino-1H-tetrazole, 1-
1 such as methyl-1H-tetrazole, 1-phenyl-1H-tetrazole, 1-amino-1H-tetrazole
1-substituted-5-substituted-1 such as 1-substituted-1H-tetrazole and 1-phenyl-5-methyl-1H-tetrazole
Examples thereof include H-tetrazole, but the present invention is not limited to these compounds. However, 1H-tetrazole is more preferred. The addition amount of the tetrazole derivative is preferably 0.01% by weight to 20% by weight based on the total weight. More preferably, the content is 0.1% by weight to 10% by weight. The total weight here means the total weight of all the paste components.

As the photopolymerization initiator, those having sensitivity up to a long wavelength are preferable. In addition to improving sensitivity by using up to long wavelengths, it is preferable to have sensitivity up to long wavelengths in order to cure the inside of a thick film because the shorter the wavelength of light is, the more susceptible to absorption and scattering. . Usually, since a mercury lamp is used for the exposure, it is preferable that the sensitivity be up to a wavelength of 436 nm, which is the g-line of the long-wavelength emission line spectrum of the mercury lamp. Further, a composite initiator system having a g-ray sensitivity by adding a sensitizer to a photopolymerization initiator having sensitivity only at a short wavelength can be suitably used.

As such an initiator, for example, an initiator having sensitivity to g-ray is 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1 or bis (2 , 4,6-trimethylbenzoyl) -phenylphosphine oxide and the like, which have no sensitivity to g-rays.
An initiator system which gives g-line sensitivity by making 2,4-diethylthioxanthone act as a sensitizer on 1 [4- (methylthio) phenyl] -2-morpholinopropan-1-one is exemplified. However, the photopolymerization initiator system that can be used in the present invention is not limited to these.

When a large amount of light is irradiated to cure the inside of the film, it is preferable to add an ultraviolet absorber made of an organic dye in order to prevent the pattern near the surface from being spread by the scattered light and the pattern becoming large. . Further, in order to prevent a light beam from reaching the inside of the thick film due to absorption by the light absorbing agent, it is desirable that the light absorbing agent reduce the absorbance by irradiation with the light beam. As organic dyes, azo dyes and benzophenone dyes are preferred. For example, azo dyes such as Sudan Blue, Sudan R, Sudan II,
Examples include Sudan III, Sudan IV, Oil Orange SS, Oil Violet, and Oil Yellow OB. Examples of the benzophenone-based dye include Ubinal D-50, Ubinal MS40, and Ubinal DS49, but are not limited thereto.

The amount of the ultraviolet absorber added is preferably 0.01 to 1% by weight. If it is less than 0.01% by weight, the effect of suppressing the spread of the pattern due to the addition is low. If it exceeds 1% by weight, the absorption is too large and the curing inside the film is hindered.

The paste of the present invention can be obtained by uniformly mixing the above components with a kneading device or a dispersing device such as a three-roll mill or a coball mill. An example will be described. After the organic components are completely and uniformly mixed by a mixer or a stirrer, a conductor powder is added, and the mixture is further mixed and pre-dispersed. Thereafter, the mixture is kneaded through a three-roll mill. Preferably, the three-roll mill is passed continuously two to eight times.

Next, an example of forming a conductive pattern using the photosensitive paste according to the present invention will be described, but the present invention is not limited to this.

A paste is applied on an alumina substrate, a glass substrate, or the like by screen printing and dried. 70 ° C-10
After drying by heating at 0 ° C. for a few minutes to 1 hour. Exposure is through a mask. For the mask, use a negative type for the desired pattern shape, and perform exposure with a high-pressure mercury lamp, etc.
The exposure amount is, for example, 10 as measured by i-line (365 nm).
Irradiate at ~ 300 mJ / cm ² . After exposure, development is performed using an alkaline aqueous solution as a developer. The alkaline aqueous solution is preferably an organic alkali such as tetramethylammonium hydroxide or ethanolamine in order to prevent residual metal components. After developing with a developer for a predetermined time, washing is performed with water. These development and water washing can be performed by dipping, spraying, paddle, or the like, but spray development is preferred because a high resolution can be obtained and a pattern having a rectangular cross-sectional shape can be obtained. The spraying time of the developing solution is 20 seconds to 200 seconds, and the washing with water is also performed by spraying for 10 seconds to 60 seconds. It is preferable to rotate the substrate during spraying from the viewpoint of uniformity of development. The rotation speed is preferably 100 to 1000 rpm. After washing with water, spin up to shake off excess water and dry. The rotation speed at this time is 1000 to 4000 rotations. If necessary, after completely removing the water with an oven or the like, firing is performed in an electric furnace, a belt furnace, or the like to volatilize organic components and sinter inorganic powder to form a conductor film or an insulating film. The firing atmosphere and temperature vary depending on the type of the conductor and the substrate.
In a nitrogen atmosphere containing 10 to 100 ppm of oxygen, a hydrogen atmosphere, or the like, firing is performed at a temperature of 500 to 1600 ° C. for 1 to 60 minutes.

The pattern formed by the photosensitive paste of the present invention is suitable for MC mounted on a notebook computer or a mobile phone.
M (multi-chip module) substrates, CSP (chip size package) substrates, chip components such as chip inductors and chip capacitors, electrodes and insulating layers on module substrates, etc.
It is suitably used for electrodes for plasma display panels and insulator patterns.

[0031]

The present invention will be described in detail with reference to the following examples, but the present invention is not limited by these examples. For each composition (parts by weight) shown in Tables 1 and 2, the paste was adjusted in the manner described below, and a pattern workability test was performed. The raw materials used are shown below.

A. Inorganic powder a. Copper powder for conductor paste Monodispersed granular Average particle size 3.6 μm Specific surface area 1.0 (m ² / g) Tap density 4.5 (g / cm ³ ) (manufactured by Dowa Mining) b. Glass powder for insulating paste Monodispersed sphere Average particle size 2.7 μm Specific surface area 1.91 (m ² / g) Glass transition point 670 ° C. c. Alumina ceramic mixed powder for insulating paste Average particle size 3.4μ
m Specific surface area 2.01 (m ² / g) The average particle size is Microtrac (Leeds + Nort)
hrup). B. Polymer Glycidyl methacrylate-modified methacrylic acid-methyl methacrylate copolymer Molecular weight 30,000 Acid value 110 (weight average molecular weight was obtained by gel permeation chromatography (GPC) in terms of polystyrene).

C. B. Multifunctional monomer Dipentaerythritol hexaacrylate, pentaacrylate mixture Hexafunctional monomer DPHA (manufactured by Nippon Kayaku) Tetrazole derivative a. 1H-tetrazole b. 5-methyl-1H-tetrazole c. 5-phenyl-1H-tetrazole d. 5-amino-1H-tetrazole e. 1-methyl-1H-tetrazole f. Benzotriazole.

E. B. Photoinitiator 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1 (Irgacure 369 of Ciba Specialty Chemicals: hereinafter referred to as IC369) Solvent γ-butyrolactone G. Dispersant Dispersant a: “NOPCOSPARSE 092” (manufactured by San Nopco) Absorbent Sudan IV (Tokyo Kasei) I. Leveling agent LC-951 (Kusumoto Kasei) (effective concentration is 10% by weight, remainder is solvent) Glass frit Glass frit a: ZrO ₂ (42), B ₂ O ₃ (2
4), SiO ₂ (21), Li ₂ O (7), Al ₂ O
₃ (4) Other oxides (2) Unit:% by weight Developer Tetraethylammonium hydroxide 0.1% by weight
Aqueous solution.

The following operations were all performed under yellow light. Preparation of paste (1) A polymer and a solvent were mixed and heated at 60 ° C. for 3 hours to be dissolved. (2) Cool the polymer solution to room temperature, mix all other components, and use a motor and a stirring blade at 200 rpm to 3
Mix thoroughly completely for 0 minutes at room temperature. (3) The obtained slurry was rolled with three rolls (EXACT
Model 50) to obtain a paste.

Pattern processing (1) The paste was applied on the entire surface of a 96% alumina substrate of 7.5 cm square (manufactured by Nikko) by screen printing. The screen uses SUS # 325 mesh. Conductor paste is printed once, insulating paste is 80 ° C after first printing
After 10 minutes of preliminary drying, the second overprinting was performed. (2) The printed substrate was dried in a hot air oven at 80 ° C. for 40 minutes. The film thickness after drying is 15 μm for the conductive paste,
The thickness of the insulating paste was 35 μm. (3) Using a high-pressure mercury lamp (15 mW / cm ² ), the paste was exposed through a pattern mask. The pattern mask for the conductor paste is a line / space pattern, and the line width / space is 30/30, 40/40,
50/50, 60/60, 70/70, and 80/8
0 (unit: μm) was used. ◎ indicates that a 30 μm pattern could be resolved, ○ indicates that a 50 μm pattern could be resolved, and Δ indicates that a 80 μm pattern could be resolved.
When the resolution was lower than that or when development was impossible, it was described in Table 1 as x. The pattern mask for the insulating paste is a through-hole mask of 50 μmφ. 50
When μmφ could be resolved, it was evaluated as ◎. (4) The exposed substrate was immersed in an alkali developing solution (0.1% TMAH aqueous solution), developed by shaking, and then rinsed with a water shower. (5) The pattern was observed with an optical microscope.

Stability test (1) The viscosity was measured immediately after the paste was prepared. (2) After standing at room temperature for one week, the viscosity was measured again. The results are all shown in Tables 1 and 2.

In Examples 1 to 11, copper powder was used in Example 1.
2 uses glass powder, and Example 13 uses ceramic powder. In Examples 3, 4, and 5, pastes having good storage stability and developability were obtained. In Examples 6 and 7, although the pattern resolution was not so good, very stable results were obtained in storage stability. In Examples 8 to 11, both the storage stability and the pattern workability were good. From Examples 12 and 13, storage stability and developability were both good in both glass and ceramics. Comparative Example 1,
Sample No. 2 had poor storage stability due to high reactivity with copper. In Comparative Examples 3 and 4, storage stability was poor because of high reactivity with the metal oxide in the glass powder. In Comparative Example 5, the storage stability was poor because of high reactivity with the metal oxide in the ceramic powder.

[0039]

[Table 1]

[0040]

[Table 2]

[0041]

According to the present invention having the above-mentioned constitution, the thickening and solidification of the photosensitive paste are prevented, the storage stability is good, the development time can be easily controlled, and the resolution is good. A photosensitive paste can be obtained.

 ──────────────────────────────────────────────────続 き Continued on front page F term (reference) 2H025 AA00 AA11 AB17 AB20 AC01 AD01 BC13 BC31 CB13 CB14 CB43 CC20 DA19 FA17 2H089 HA36 TA02 TA05 4E351 AA07 AA13 BB01 BB31 CC12 CC22 CC27 DD01 DD04 DD29 DD31 DD41 EE10 EE10 EE21 EE27 GG16 GG20

Claims (7)

[Claims] 1. A photosensitive paste comprising an inorganic powder and a photosensitive organic component as essential components, comprising a tetrazole derivative. 2. The photosensitive paste according to claim 1, wherein said inorganic powder contains at least copper powder. 3. The photosensitive paste according to claim 1, wherein the inorganic powder contains at least glass powder. 4. The photosensitive paste according to claim 1, wherein said inorganic powder contains at least a ceramic powder. 5. The photosensitive paste according to claim 1, wherein said tetrazole derivative contains 1H-tetrazole. 6. The tetrazole derivative in an amount of 0.01
2. The photosensitive paste according to claim 1, comprising from 20% by weight to 20% by weight. 7. The photosensitive paste according to claim 1, comprising 0.1 to 10% by weight of the total weight of the tetrazole derivative.