JPH0661602A - Production of electronic circuit board - Google Patents

Abstract

(57) [Summary] [Construction] In a method for producing an electronic circuit board, wherein a conductive paste is applied or printed on a metal surface on a substrate and then cured to form a conductive coating film, the metal surface is preliminarily coupled with a coupling agent. The present invention relates to a method for manufacturing an electronic circuit board, which comprises applying or printing a conductive paste after the treatment. [Effect] According to the manufacturing method of the present invention, it is possible to obtain an electronic circuit board which can improve the adhesiveness without lowering the conductivity and can maintain the high adhesiveness especially in the solder heat resistance test after absorbing moisture. . Therefore, it is possible to easily and stably form an electromagnetic wave shield layer having extremely high reliability and high effect on the circuit board. Further, it is possible to form a highly reliable wiring on the substrate, and these effects are extremely large industrially.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an electronic circuit board using a conductive paste, and more particularly to a method for manufacturing a printed circuit board and a printed wiring board for EMI (electromagnetic interference) countermeasures.

[0002]

2. Description of the Related Art Printed circuit boards using a conductive paste are excellent in performance, particularly in terms of conductivity, and therefore various proposals have been made to date. However, it has been pointed out that, in addition to the problem that the silver paste is expensive, the use of silver powder causes the migration of silver when left under high humidity under load. . It has been pointed out that due to this problem, a high-density circuit cannot be obtained, inter-layer insulation failure occurs when multiple layers are formed, and the stability of the resistance formed between the electrodes cannot be obtained. . As a method for avoiding these problems, in recent years, research on circuit fabrication using a copper paste, which is cheaper than silver and has good migration resistance, has been widely conducted.

However, in the case of a circuit using a copper paste, although the migration phenomenon can be prevented, it is susceptible to oxidative deterioration, and therefore, there has been a practical problem in terms of maintaining conductivity for a long period of time. Also, with conventional copper paste, the adhesion with the resist used for the printed circuit board is not good depending on the type of resist,
It has been pointed out that the conventional copper paste is inferior to the conventional copper paste even in close contact with the surface of a metal such as copper, gold or platinum forming a contact terminal on the substrate.

Attempts have also been made to use a conductive paste as an electromagnetic wave shielding material for circuit boards. That is, this application is for a printed wiring board in which a conductive layer having a circuit pattern including a ground pattern is formed on a substrate, except for a part of the ground pattern on the surface of the substrate on which the conductive layer is provided. An insulating layer is provided so as to cover the layers, and an electromagnetic wave shielding layer is formed by printing a conductive paste so as to cover the insulating layer of the board and connect it to the ground pattern. Used as (Japanese Patent Laid-Open No. 63-
No. 15497, Japanese Patent Laid-Open No. 4-30598, and Japanese Utility Model Publication 55-2927.
(See Publication No. 6). However, in this method, in the solder heat resistance test at the time of moisture absorption, the adhesiveness is significantly lowered, and the conductivity and the like are not always satisfactory, and these have been pointed out as problems.

[0005]

On the other hand, various kinds of additives such as antioxidants, reducing agents and metal chelating agents are added to the conductive paste used in printed circuit boards and printed wiring boards for EMI countermeasures. Is being done. For example, a method of using salicylic acid and its derivative as an antioxidant for a conductive copper paste (JP-A 1-158081), and a method of using γ-aminoisopropyltriethoxysilane as a reducing agent (JP-A-50-6638). Issue) and 2
-Hydroxy-3-phenoxypropyl phosphite (JP-A-52-24936), metal chelating agents such as monoethanolamine and diethanolamine (JP-A-62-230869) and acetylacetone A method using the above (Japanese Patent Laid-Open No. 2-66802) has been proposed.

However, the conductive copper paste containing the above additives has been improved in terms of improving or maintaining the conductivity, but has another physical property, that is, adhesion with the surface of the copper foil (particularly the surface of the metal copper). There was a strong demand for further improvement. In particular, the relationship between conductivity and adhesion is generally a trade-off relationship, which has been a major obstacle to the development of conductive pastes. Therefore, it is expected in the art to develop an electronic circuit board using a conductive copper paste that has excellent conductivity and adhesion, durability, and basic physical properties.

It is an object of the present invention to solve this problem, and to solve this problem, a conductive paste, in particular,
Even when using a metal that is easily oxidized as a conductive powder, it has excellent adhesion to the metal surface on the substrate, conductivity, durability, etc., and is particularly high during the solder heat resistance test after absorbing moisture. An object of the present invention is to provide a method for manufacturing an electronic circuit board that maintains adhesion.

[0008]

In view of the present situation, the inventors of the present invention have made earnest studies on the adhesion between the conductive paste and the metal surface on the substrate and the maintenance of the conductivity, and as a result, the metal surface was coupled. It was found that the above object can be achieved by printing and curing a conductive copper paste after the treatment with an agent, and completed the present invention.

That is, the gist of the present invention is that after applying or printing a conductive paste on a substrate having a metal on a part of its surface,
In a method for manufacturing an electronic circuit board having a step of curing to form a conductive coating film, an electronic circuit board is characterized in that the metal surface is previously treated with a coupling agent and then a conductive paste is applied or printed. The present invention relates to a manufacturing method of.

In the present invention, by pre-treating the metal surface with the coupling agent in this way, the metal surface and the conductive paste cured coating film exhibit high adhesion, and further, this performance is a copper foil. It does not depend on the surface state (oxidation state) of. And since this performance does not sacrifice the conductivity and durability of the conductive paste itself,
As described above, it is possible to improve both conductivity and adhesion, which are generally in a trade-off relationship.

Examples of the coupling agent used in the present invention include, but are not limited to, silane-based, chromium-based, titanium-based, tin-based, zirconium-based, and aluminum-based coupling agents. Among them, the silane coupling agent is preferable from the viewpoint of improving the adhesion between the conductive paste and the metal surface on the substrate. Examples of the silane coupling agent include silane coupling agents represented by the general formula (1).

[0012]

[Chemical 2]

[In the formula, A is Cl, -OC _n H _{2n + 1} , -N
_{CO, CH 2 = C (CH} 3) hydrolyzable groups selected from -O-; T is H, F, CF _3, amino group, alicyclic epoxy group, an epoxy group, a carboxyl group, a hydroxyl group, a phenol group, Phenyl group, acetal group, alkyl group, alkoxy group, methacryloxy group, Schiff base, silanol group, thiol group, vinyl group, quaternary ammonium salt, isocyanate group, metal, imidazole group, polyoxyalkylene group; E is a carbon number 1 20 alkyl groups; R is O;
S, NH, NR '(R ' represents Ar or C _n H _{2n + 1),} represents OCO, COO, and Ar. f is an integer of 1 to 3, and f A's may be the same or different,
The (3-f) E's may be the same or different. g is an integer of 0 to 10; h is an integer of 0 or 1; i is an integer of 0 to 10. However, when A is an NCO group, T is selected from functional groups other than amino group, carboxyl group, hydroxyl group, thiol group and imidazole group. ]

Among these silane coupling agents, among others, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, N- ( 2-aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltriethoxysilane, N-
(2-aminoethyl) -3-aminopropylmethyldimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldiethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane Ethoxysilane, alkyltrimethoxysilane (alkyl group is C4 to C18), alkyltriethoxysilane (alkyl group is C4 to C18), dimethyldimethoxysilane and dimethyldiethoxysilane are preferably used.

In the present invention, a partially hydrolyzed product of the above coupling agent can be preferably used. That is, by hydrolysis, a methoxy group, an ethoxy group, or the like becomes a hydroxyl group, and better adhesion can be obtained. At this time, the hydrolysis method is not particularly limited, and for example, it may be stored as an aqueous solution using the above-mentioned silane coupling agent and stored at room temperature for several hours. The hydrolyzability can be controlled by modifying the silane coupling agent with a solvent such as butyl carbitol. Further, partial hydrolysis may be confirmed by NMR or the like. Here, the partial hydrolysis means that one or two of the di- or trimethoxy group or the di- or triethoxy group of the silane coupling agent is hydrolyzed to a hydroxyl group. The above coupling agents may be used alone or
A mixture of two or more species can be used.

The method for producing the coupling agent in the present invention is not particularly limited, and for example, the amino group-introduced type can be obtained by subjecting trichlorosilane or methyldichlorosilane to a hydrosilylation reaction with an amine analog. . It is also possible to use a commercially available coupling agent.

In the manufacturing method of the present invention, the metal surface on the substrate is previously treated with a coupling agent, and then a conductive paste is applied or printed. The method for treating the metal surface with the coupling agent is coupling. It suffices that the treatment liquid containing the agent can be brought into contact with the metal surface for a certain amount of time for a certain period of time, and a known method such as a dipping method, a spray method or coating with a brush can be used. As the treatment liquid, one obtained by dissolving the coupling agent in a solvent such as water, alcohols, cellosolves, carbitols or the like is usually used, and the concentration of the coupling agent in the treatment liquid is usually 0.0
It is 5% by weight or more, preferably 0.1% by weight or more. If the amount is less than 0.05% by weight, the amount of the coupling agent adsorbed on the surface of the metal substrate is small, so that the improvement in adhesion is small, and it takes time to increase the amount adsorbed, which is not preferable.

The processing time is usually 1 second to 60 minutes,
It is preferably several seconds to 30 minutes. If it exceeds 60 minutes, the productivity is low and it is not preferable. The treatment temperature is not particularly limited, but is about 0 to 80 ° C., and room temperature to 60 ° C. is preferably used in view of workability. In the present invention, before the treatment with such a coupling agent, the copper foil may be pretreated in order to remove the surface oxide film and enhance the effect of the treatment. The pretreatment method is not particularly limited as long as it can remove the surface oxide film, and for example, a 10% aqueous solution of sulfuric acid / ammonium citrate (1: 3) or the like is used and the temperature is adjusted to 40 ° C. The surface oxide film may be dissolved by immersing it for 60 seconds and then air-dried with jet air or the like.

The conductive paste used in the present invention comprises a conductive powder, an organic binder, an additive and a solvent, the organic binder being a phenol resin, an amino resin, a xylene resin and a hydroxystyrene polymer. And at least one resin selected from the group consisting of derivatives thereof.

The organic binder of the conductive paste used in the present invention contains a thermosetting resin as an essential component, and the thermosetting resin effectively used in the present invention includes the above-mentioned phenol resin, amino resin and xylene. In addition to resin, urea resin, alkyd resin, silicon resin, furan resin, unsaturated polyester resin, epoxy resin, polyurethane resin, polyester / polyol resin, acrylic resin, methylolated hydroxystyrene polymer and / or its derivative, etc. The known thermosetting resin can be used.
Of these, excellent interaction with the coupling agent,
Phenol resins, amino resins, and xylene resins that are easy to obtain the effect of improving the adhesion are preferable, and amino resins and xylene resins that are particularly remarkable in the effect of improving the adhesion are most preferable. The thermosetting resins used in the present invention may be used as a mixture of two or more kinds.

As the phenolic resin, generally known ones and commercially available ones can be used. For example, phenol, cresol, xylenol, p-alkylphenol, chlorophenol, bisphenol A, phenolsulfonic acid, resorcin, various modified phenols and the like phenols. A resin obtained by adding and condensing an aldehyde such as formalin and furfural to a resin having a hydroxyl group. Resol type phenol resin is particularly preferable. When a novolac type phenol resin is used, it is preferable to use hexamethylenetetramine together.

As the amino resin, generally known ones,
Although a commercially available product can be used, one having a weight average molecular weight of 500 or more and 50,000 or less is preferable. For example, urea,
Resins in which formalin is added and condensed to amino groups such as melamine, guanamine, aniline, and sulfonamide, or epoxy-modified melamine resin, phenol-modified melamine resin, acryl-modified melamine resin, butylated urea resin, butylated urea melamine co-condensed resin, butyl Melamine / guanamine co-condensation resin, amino / alkyd co-condensation resin, alkyl etherified melamine resin and the like. Alkyl etherified melamine resin is preferable.

As the alkyl etherified melamine resin, there are methyl etherified melamine resin, n-butyl etherified melamine resin, iso-butyl etherified melamine resin, and the like. For example, Super Beckamine (trade name) manufactured by Dainippon Ink and Chemicals, Inc. Alternatively, there is Uban (trade name) manufactured by Mitsui Toatsu Chemicals, Inc. Among these alkyl etherified melamine resins, the preferable one is the weight average molecular weight (M
w) is in the range of 500 to 50,000, and the degree of etherification thereof is in the range of 10 to 95% (6 alkyl ether groups are introduced to one unit of the triazine ring at 100%), more preferably Mw. It is in the range of 1,000 to 25,000 and the degree of etherification is in the range of 20 to 80%. Mw is 50
If it is less than 0, the flexibility of the cured coating film will be insufficient, and if it exceeds 50,000, the adhesion resistance and conductivity will be poor. When the etherification degree is less than 10%, the melamine is unstable, and the pot life of the conductive paste becomes short, and when it exceeds 95%, the curing speed decreases, and a sufficient dense coating cannot be obtained under normal curing conditions, and adhesion resistance This is because it becomes difficult to obtain properties, conductivity, and the like.

The most preferred alkyl etherified melamine resin among these is represented by the general formula (2)

[0025]

[Chemical 3]

[Wherein, among the substituents of U ^{1 to} U ⁶ ,
4 are hydrogen atoms, the rest represent -CH ₂ OU ',
U'represents a hydrogen atom or an alkyl group having 3 or more carbon atoms. However, the number of —CH ₂ OU ′ groups (U ′ is an alkyl group) / the number of —CH ₂ OU ′ groups (U ′ is a hydrogen atom or an alkyl group) is in the range of 0.7 to 1.0. ] At least 50 mol% or more of the melamine formaldehyde compound represented by the following (hereinafter abbreviated as MF compound) is contained in the resin.

The MF compound in the present invention is (1) U ¹
Among the substituents of ~U ^6, a 1-4 is a hydrogen atom (presence 1-4 is NH groups of free not methylolated), rest 'represent, U' -CH ₂ OU is a hydrogen atom or Represents an alkyl group having 3 or more carbon atoms. ₍₂₎ (- CH 2 O
U ′ group (U ′ is an alkyl group)) / (— CH ₂ OU ′ group (U ′ is a hydrogen atom or an alkyl group)) is 0.7 to 1.
In the range of 0, that is, at least 70% or more of the number of methylol groups bonded to the melamine skeleton is alkyl etherified, and the ratio of free methylol groups is less than 30%. The alkyl etherified melamine resin according to the present invention Is characteristic in containing 50 mol% or more of such an MF compound.

In the above-mentioned MF compound, when 5 or more of the substituents of U ^{1 to} U ⁶ are hydrogen atoms, that is, when the number of bound formalin is 1 or less, the solvent or the mixture of the produced melamine resin is used. The compatibility with the hydroxystyrene copolymer and / or its derivative becomes poor,
The possibility that melamine resin will precipitate increases. Further, when all the substituents of U ^{1 to} U ⁶ are not hydrogen atoms, that is, when all of them are —CH ₂ OU ′, the adhesion to the base material is lowered.

Further, the (-CH ₂ OU 'group (U' is an alkyl group)) / (-CH ₂ OU 'group (U' is a hydrogen atom or an alkyl group)) is less than 0.7, that is, -CH ₂ When the proportion of free methylol groups in the OU 'group is 30% or more, the flexibility of the obtained coating film becomes poor. U'here
May be linear or branched as long as it is an alkyl group having 3 or more carbon atoms, and one having 3 or more carbon atoms is usually used.
It preferably has 3 to 10 carbon atoms. Further, when U ′ is an alkyl group having 2 or less carbon atoms, there is a problem of poor printability, which is not preferable. Further, if the content of the MF compound in the melamine resin is less than 50 mol%, excellent coating film physical properties cannot be obtained.

The above-mentioned melamine resin is produced, for example, by reacting melamine with formalin and performing alkyl etherification with an excess of alcohols. In this case, the amount of formalin to be reacted is appropriately 2 to 5 per 1 melamine nucleus, and the bound methylol group is 70
% Or more is required to be alkyl etherified.

The MF compound in which U'in the general formula (2) is an alkyl group is produced, for example, by using a compound represented by U'OH as an alcohol through the following reaction.

[0032]

[Chemical 4]

Examples of the alcohols used in the alkyl etherification reaction in this case include U'-containing aliphatic or alicyclic alcohols having 3 or more carbon atoms. When a melamine resin modified with an alcohol having 2 or less carbon atoms is used, it is impossible to maintain the performance satisfactory in the workability of printing (generation of pin holes or the like in the coating film) as described above. The weight average molecular weight of the alkyl etherified melamine resin thus obtained is preferably 300 to 20,000, more preferably 800 to 10,000. Molecular weight is 30
This is because if it is less than 0 or greater than 20,000, the conductivity decreases. In addition, the weight average molecular weight / number average molecular weight ratio of the melamine resin is preferably 1 to 5.

As the xylene resin, generally known ones and commercially available ones can be used, and examples thereof include resins obtained by adding and condensing aldehydes such as formalin and furfural to xylene and modified xylene.

In the present invention, it is preferable to use a thermoplastic resin together with the thermosetting resin. The thermoplastic resin effectively used in the present invention includes a hydroxystyrene polymer and / or a derivative thereof, a saturated polyester resin, a polyurethane resin, a polyamide resin, an acrylic resin, a butyral resin, a novolac type phenol resin,
A known thermoplastic resin such as a thermoplastic xylene resin can be used. Particularly, a hydroxystyrene polymer and / or its derivative is preferably used. The thermoplastic resins used in the present invention may be used alone or in combination of two or more.

The hydroxystyrene-based polymer and / or the derivative thereof preferably has a weight average molecular weight of 1,000 to 2,000,000. The addition of this binder component not only increases the interaction with the coupling agent and further promotes the improvement of the adhesion to the metal surface,
Performance such as conductivity and durability is also improved. This hydroxystyrene-based polymer and its derivative are described in JP-A-3-22
83, JP-A-3-2248, and JP-A-3-173007). For example, those represented by the following general formula (3) can be mentioned.

[0037]

[Chemical 5]

[Wherein 1 and m are 1 ≧ 0 and m ≧ 3, and the average molecular weight of the organic polymer of the general formula (3) is 1000, respectively.
Up to 2 million, k, p, and u represent average values in the polymer, and their ranges are 0 ≦ k ≦ 2 and 2, respectively.
0 ≦ p ≦ 2, 0 ≦ u ≦ 2, but k + p + u> 0, R ¹ ~
R ³ is a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, Q is a polymerizable vinyl monomer, Y and Z are the same or different, and

[0039]

[Chemical 6]

Alternatively, it is selected from an alkyl group having 1 to 18 carbon atoms or an aryl group. (In the formula, M is a hydrogen atom, an organic cation such as an alkali metal, an alkaline earth metal or an amine, Y ¹ and Y ² are halogens, Y ³ is a halogen ion, a counter ion such as an organic acid anion and an inorganic acid anion, W is S or O, R ^{4 to} R ⁸ are the same or different, and are alkyl derivatives such as linear or branched alkyl groups or hydroxylalkyl groups, aromatic groups or hydrogen atoms, and R ⁶ and R ⁷ are N groups. R ^{9 to} R ¹⁵ are the same or different and are linear or branched alkyl groups, or alkyl derivatives such as hydroxylalkyl groups, aromatic groups, or hydrogen atoms, q, s. Is 0
Alternatively, 1 and r represent 0, 1 or 2. )]

The hydroxystyrene-based polymer represented by the general formula (3) and the derivative thereof have a hydroxy group which may or may not have a substituent represented by Y or Z in the general formula (3). Styrene, hydroxy-
Copolymer of only hydroxystyrene-based monomers such as α-methylstyrene or hydroxy-α-ethylstyrene, or these hydroxystyrene-based monomers and other polymerizable vinyl-based monomers (Q) Can be a copolymer of The hydroxystyrene-based monomer of the polymerized unit may be an ortho body, a meta body, a para body or a mixture thereof, but a para body or a meta body is preferable.

Other vinyl-based monomers (Q) in the case of copolymers include anionic and cationic ionic monomers, nonionic monomers, methacrylates, vinyl esters, vinyl ethers, Known compounds such as malate and α-olefin can be mentioned. In the present invention, as described above, the copolymerization of hydroxystyrene-based monomers may be carried out, but when copolymerized with another polymerizable vinyl-based monomer (Q), a hydroxystyrene-based monomer is used. The ratio of the body / the other vinyl-based monomer (Q) is preferably 1/10 to 20/1 in terms of molar ratio. If the ratio of the vinyl-based monomer (Q) exceeds the hydroxystyrene-based monomer by 10 times (molar ratio), the effect of the hydroxystyrene-based monomer will not be exhibited, which is not preferable, and the vinyl-based monomer (Q When the ratio of () is less than 1/20, the effect of copolymerization is not exhibited, so it is not necessary to dare to copolymerize with the vinyl-based monomer (Q). Therefore, in the present invention, the number of such vinyl monomers (Q) is m ≧ 0.

These hydroxystyrene polymers and their derivatives can be easily prepared by a known method (CG Overberger, JC Salamone, S. Yaroslavsky,
J. Am. Chem. Soc., 89, 6231 (1967); DI Packham, J. Chem. So
c., 2617 (1964); M.Kato, J.Polym.Sci., Part A-1,7,2175
(1969)).

The content of the binder in the conductive paste used in the present invention is 5 to 50 based on the total weight excluding the solvent.
% By weight, preferably 5 to 40% by weight. When the amount is less than 5% by weight, the absolute amount of the binder is insufficient, the adhesiveness is reduced, the fluidity of the resulting composition is deteriorated, and the printability is reduced. At the same time, the conductive powder is likely to be oxidized during heat curing, resulting in deterioration of flexibility and conductivity. On the contrary, when the amount of the binder exceeds 50% by weight, the absolute amount of the conductive powder is insufficient and the conductivity required for forming a circuit cannot be obtained.

As the conductive powder used in the present invention,
One or more metal powders selected from the group consisting of copper powders, silver powders, nickel powders, aluminum powders and palladium powders, and solid powders having a metal layer consisting of a coating layer of the above-mentioned metal on the surface can be mentioned. In terms of conductivity, copper powder is particularly preferable. The form of the conductive powder may be any of dendritic, flake-like, spherical, and indefinite, but is preferably dendritic electrolytic copper powder produced by electrolysis or spherical powder. The average particle diameter is preferably 30 μm or less, and from the viewpoint of high density and multi-contact filling, dendritic powder having a particle diameter of 1 to 10 μm is more preferable. However, the average particle size here is "L
The volume-based median diameter determined by "A-500 type laser diffraction type particle size distribution measuring device". This is because if the average particle size exceeds 30 μm, it becomes difficult to densely fill the conductive powder, the conductivity is lowered, and the printability is deteriorated. Further, when the surface-treated copper powder is used, particularly excellent conductivity and durability are easily obtained. Even an organic surface treatment agent may be used. The conductive powder may be used alone or in a mixed system. It is preferable that the purity of the metal powder is high. In particular, the copper powder is most preferably the same as the purity of the copper foil or the plated copper layer used for the conductor of the circuit board.

The conductive powder used in the present invention is compounded in an amount of 50 to 50 with respect to the total weight excluding the solvent.
It is used in the range of 95% by weight, preferably 70 to 90% by weight, more preferably 80 to 90% by weight. If the blending amount is less than 50% by weight, sufficient conductivity cannot be obtained. On the contrary, if the blending amount exceeds 95% by weight, the conductive powder is not sufficiently bound, the coating film obtained becomes brittle, and the moisture resistance decreases and the conductivity is reduced. It also becomes worse.

The conductive paste used in the present invention includes:
As the additive, one or more kinds of benzoic acid and / or its derivative, ester carboxylic acids, ether carboxylic acids, known reducing agents or chelating agents can be used. (For example, Japanese Patent Application No. 2-341074, Japanese Patent Application No. 2-34
Compounds described in No. 1076, or known compounds can be mentioned. )

Preferably, benzoic acid, methylbenzoic acid, ethylbenzoic acid, propylbenzoic acid, butylbenzoic acid, hexylbenzoic acid, octylbenzoic acid, nonylbenzoic acid,
Decylbenzoic acid, dodecylbenzoic acid, tetradecylbenzoic acid, hexadecylbenzoic acid, octadecylbenzoic acid,
Benzoic acid and / or its derivatives such as methoxybenzoic acid, ethoxybenzoic acid, butoxybenzoic acid, octyloxybenzoic acid, tetradecyloxybenzoic acid, monohexyl oxalate, monohexyl malonate, monohexyl succinate, monooctyl succinate, succinic acid Acid monooleyl, glutaric acid monohexyl, adipic acid monohexyl, maleic acid monohexyl, maleic acid monooctyl, maleic acid monooleyl, monomethyl phthalate, monobutyl phthalate, phthalic acid monohexyl, phthalic acid monooctyl, phthalic acid monooleyl, naphthalenedicarboxylic acid monohexyl, Pelargonoyloxyacetic acid, oleoyloxyacetic acid, 3-peragonoyloxypropionic acid, 3-oleoyloxypropionic acid, 4-peragonoyloxybutanoic acid, 6 Butyryloxy hexanoic acid,
Ester carboxylic acids such as enanthyloxybenzoic acid and enanthyloxynaphthoic acid, octyloxyacetic acid, dodecyloxyacetic acid, tetradecyloxyacetic acid, 3
-(Octyloxy) propionic acid, 3- (dodecyloxy) propionic acid, 4- (octyloxy) butanoic acid, 6- (butoxy) hexanoic acid, 8- (butoxy) octanoic acid, butylphenoxyacetic acid, octylphenoxyacetic acid, Ether carboxylic acids such as 3- (butylphenoxy) propionic acid, alkanolamines such as triethanolamine, alkylamines such as triethylamine and palmitylamine, o-aminophenol, 2-amino-
4-methylphenol, o-aminothiophenol, 8
-Aromatic amino compounds such as hydroxyquinoline, 2-methyl-8-hydroxyquinoline, 1-nitroso-2-naphthol, 1- (2-pyridylazo) -2-naphthol, succinic acid, propionic acid, humic acid, etc. Hydroxycarboxylic acids such as carboxylic acid, citric acid, and ascorbic acid, salicylic acid compounds such as salicylic acid, sulfonylsalicylic acid, salicylamide, salicylhydroxysamic acid, amino acids such as phenylalanine, tyrosine, anthranilic acid, aspartic acid, and imino acids such as proline , Pyridinecarboxylic acid such as nicotinic acid, hydrazine, hydrazines such as phenylhydrazine, benzoylacetone,
Examples include β-diketones such as acetylacetone, lauryl mercaptan, and the like. The selection of the additives as described above is also one of the important factors that affect the adhesion improving effect.

In the conductive paste used in the present invention, the compounding amount of the above additives is usually 0.1 to 20 parts by weight, preferably 0.5 to 10 parts by weight, based on the total weight excluding the solvent. If the amount is less than 0.1 part by weight, the effect of addition is not sufficient, and if it exceeds 20 parts by weight, the adhesion and the migration resistance are deteriorated, which is not preferable. Further, as an additive, a known thixotropic agent or leveling agent can be appropriately used as necessary for the purpose of improving the dispersibility of the copper powder and the screen printability of the paste.

In order to produce the conductive paste used in the present invention, it is adjusted by sufficiently uniformly kneading it with a disper, a ball mill, a triple roll or the like. As the solvent that can be used here, benzene, toluene, hexanone or methyl isobutyl ketone, methyl amyl ketone or butyl carbitol, butyl carbitol acetate, butyl cellosolve, butyl cellosolve acetate, propylene glycol monomethyl ether acetate, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether. Ethylene- or propylene-based glycol ethers such as triethylene glycol dimethyl ether, monobutyl ether, tetraethylene glycol dimethyl, dimethyl adipate,
Examples thereof include known solvents such as diester salts of dibasic acids such as dimethyl glutarate and dimethyl succinate. The blending amount of the solvent varies depending on the type of kneading machine, the kneading conditions and the type of solvent. It is preferable to adjust the amount of the solvent so that the paste viscosity after the kneading can be screen-printed.

In the present invention, the above-mentioned conductive paste is used to manufacture an electronic circuit board after treatment with a coupling agent. Specifically, the following method is used. An electromagnetic wave shield layer provided on a circuit board by using the manufacturing method of the present invention
In the case of producing an MI countermeasure printed wiring board, for example, there are the following methods. That is, an insulating layer is provided by applying a heat-curable or ultraviolet-curable organic insulator on a conductive circuit formed by a metal-clad laminate by an etching method except the ground pattern portion. Then, treated with a coupling agent according to the present invention, after drying, using a conductive copper paste, the conductive copper paste is applied to almost the entire surface of the insulating layer so as to be connected to the ground pattern by screen printing, By heat-curing this, a printed wiring board for EMI countermeasures having an effective electromagnetic wave shield layer (conductive coating film) can be produced. This circuit board can be effectively used as an electrostatic shield layer. The metal-clad laminated substrates that can be used are glass / epoxy resin substrates, paper / phenol resin substrates, ceramic substrates,
Any known substrate may be used as long as it is a well-known substrate described in a printed circuit technology handbook such as a polyimide resin substrate and a flexible substrate (Nikkan Kogyo Shimbun, published in 1987).
The type of metal provided on the substrate may be copper, aluminum, or the like.

Further, by the manufacturing method of the present invention, a printed circuit board on which a conductor for wiring is formed of a conductive paste, EM
When manufacturing an electronic circuit board such as a printed wiring board for I countermeasure, a method similar to the conventional method can be used except that the treatment with a coupling agent is performed. Therefore, the insulating substrate and the surface metal to be applied may be any known or commercially available substrate as described above. Line forming method is screen printing, concave plate printing,
A method of applying by spraying or brushing can be used. An electronic circuit board having an effective conductive coating film (electronic circuit) can be produced by curing this by heating or irradiation with active energy rays.

In the present invention, the action and effect of the coupling agent is more remarkably exhibited when a metallic copper substrate is used, so the present invention is particularly important for the production of an electronic circuit board using a conductive copper paste. In the present invention, the conductive coating film is obtained by drying and curing a conductive paste 1
It means a cured product or a cured coating film having a volume resistivity of × 10 ⁻² Ω · cm or less.

[0054]

The present invention will be described in more detail based on the following examples and comparative examples, but the present invention is not limited to these examples. In Examples and Comparative Examples, "%" means "% by weight".

Resin Production Example 1 Paraformaldehyde (containing 80% formaldehyde) 3 mol, n per mol of melamine in a reactor equipped with a thermometer, stirrer, reflux condenser and solvent by-product recovery device.
-Prepare 15 mol of butanol and, while stirring,
A 10 wt% aqueous solution of oxalic acid was added to adjust the pH of the reaction solution to 4.0. Thereafter, the mixture was heated and continued for 5 hours while removing water out of the system under the reflux temperature condition of the reaction solution, then cooled to 50 ° C. and adjusted to pH 7.0 with a 10% aqueous solution of caustic soda. After that, while maintaining the temperature in the system at 50 ° C or lower under heating and depressurization, excess butanol is removed from the system so that the heating residue of the resin (according to the measurement method of JIS K-5400) becomes 60%. Thus, an n-butyl etherified melamine resin (organic binder B) was obtained.

Examples 1 to 11 [Substrate preparation] Rigid substrate: (Examples 1 to 5 and 8 to 11) A glass / epoxy resin substrate (CEM-3) was used, and an adhesion test portion with a copper foil and an electrode were used. The organic insulating layer (Taiyo Ink S-222, HR-6 or MF-100S, TS-17
) Was printed and cured. For the pretreatment of the copper foil, a 10% aqueous solution of sulfuric acid / ammonium citrate (1: 3) was used.
After dipping at 40 ° C. for 60 seconds to dissolve the surface oxide film, it was air dried with jet air. -Flexible substrate: (Example 6) leaving an adhesion test portion with the copper foil on the base insulating film,
As a pretreatment, a 10% aqueous solution of sulfuric acid / ammonium citrate (1: 3) was used for immersion for 60 seconds at 40 ° C. to dissolve the surface oxide film, followed by air drying with jet air. -Printed circuit board: (Example 7) A circuit as shown in Fig. 1 was produced using a glass / epoxy resin board (CEM-3). The same method as that for the rigid substrate was used for forming the organic insulating layer and pretreating the copper foil. The substrate in which the surface of the copper foil was oxidized was prepared by heating the substrate after the pretreatment at 160 ° C. for 30 minutes.

[Hydrolysis of Coupling Agent] Using a silane coupling agent shown in Table 2, an aqueous solution having a concentration shown in Table 5 (only Example 4, using a solvent of ethanol / water = 2/1 weight ratio) was used. It was confirmed by NMR that it was stored at room temperature for about 1 day and partially hydrolyzed. This treatment liquid was used in Examples 1-9. In addition, Example 10
In No. 11, a treatment liquid which was not partially hydrolyzed was used. This treatment liquid was prepared by preparing the silane coupling agent shown in Table 2 as an ethanol solution having the concentration shown in Table 6 and then hydrolyzing it by NMR. It was used after confirming that it was not decomposed. [Coupling Agent Treatment] The above-mentioned pretreated substrate was immersed in the above silane coupling agent treatment liquid for 15 minutes at room temperature and then air-dried with jet air to obtain a test substrate. In addition, only in Example 4, the method of spraying, spraying for several seconds, and air-drying with jet air was used as the processing method. [Preparation of Paste] Conductive powders shown in Table 1, organic binders shown in Table 3, and other additives shown in Table 4 are shown in Tables 5 to 6.
The mixture was blended so as to have the composition shown in (1) and kneaded sufficiently uniformly with a disper or a triple roll to prepare a conductive paste. [Paste Printing] Each conductive paste obtained was
~ 250 mesh using a screen printer equipped with Tetoron, the adhesion test portion and the conductivity measurement pattern (2mm x 360mm) on the organic insulator, or
Printed on copper foil. Next, 10 to 30 at 140 to 160 ° C
It was heated and cured for a minute to obtain a paste cured film having a thickness of 30 to 35 μm. [Overcoat printing] Organic insulating layer (Made by Taiyo Ink MF
-200, TS-91E) is printed on the paste hardening coating film with a thickness of about 20 μm, and UV curing (high pressure mercury lamp, 1200 mj / c)
m ² ) and heat-cured at 150 ° C. for 20 minutes. Tables 5 and 6 show the results of examining various characteristics of the electronic circuit board obtained in the above process.

[0058]

[Table 1]

[0059]

[Table 2]

[0060]

[Table 3]

[0061]

[Table 4]

[0062]

[Table 5]

[0063]

[Table 6]

Measurement of Conductivity The conductivity of a coating film means the volume resistivity of a coating film which has been cured by heating with a digital multimeter (R655 manufactured by Advantest).
It is the value measured by the two-terminal method using 1). In addition,
The formula for calculating the volume resistivity is shown below. Volume resistivity (Ω · cm) = (R × t × W) / L R: Resistance value between electrodes (Ω) t: Coating thickness (cm) W: Coating width (cm) L: Electrode Distance (cm) Moisture resistance test Moisture resistance of the coating film is 3 under the environment of 60 ℃ and 95% relative humidity.
A standing test for 00 hours was performed, and the rate of change in resistance value W _R before and after the test was determined by the following equation. Resistance change rate _{W R (%) = (R} 300 -R 0) / R 0 R 0: resistance value of the coating film before test (Ω) R _{300: 300} hours the resistance after testing (Omega) W values of _R Shows the moisture resistance of the coating film as follows. A: W _R is less than 30% B: W _R is less than 30% or more ~100% C: W _R and rated the adhesiveness substrate formed by adhesion test the method more than 100%. JIS K 54
The number of cross-cuts of the coating film remaining on the copper foil or the organic insulating layer was determined by performing the test in accordance with the cross-cut cellophane tape peeling test method of 00 (1979). The judgment criteria are as follows. A: 100/100 B: 90/100 or more and less than 100/100 C: 50/100 or more and less than 90/100 D: 0/100 or more and less than 50/100 Adhesion during solder heat resistance test after absorbing moisture Test Adhesion evaluation substrate formed by the above method at 40 ° C, 90%
A test was conducted for 96 hours in a relative humidity environment, after which it was immersed in an organic acid flux bath for 4 seconds, and then in a molten solder bath (Pb / Sn = 40/60) for 10 seconds. After that, an adhesion test was conducted. The judgment criteria are as follows. A: 100/100 B: 90/100 or more and less than 100/100 C: 50/100 or more and less than 90/100 D: 0/100 or more and less than 50/100

Comparative Example 1 A conductive paste having the composition shown in Table 6 was prepared in the same manner as in Example except that the treatment with the silane coupling agent was not performed, and the rigid substrate prepared in the same manner as in Example was used. Then, the same evaluation as in the example was performed. The results are shown in Table 6.

Comparative Example 2 A conductive paste having the composition shown in Table 6 was prepared in the same manner as in Example except that the concentration of the silane coupling agent in the treatment liquid was lowered (0.01%). Using a rigid substrate prepared in the same manner as above, the same treatment and evaluation as in the example were carried out. The results are shown in Table 6.

As shown in Tables 5 and 6, the conductive coating films (Examples 1 to 11) obtained according to the present invention maintained high conductivity (10 ⁻⁴ to 10 ⁻⁵ Ω · cm). As it was, the adhesion to the metallic copper surface was greatly improved. It was also found that these physical properties are excellent in environmental stability such as moisture resistance and solder heating resistance. The case of using the treatment liquid containing the partially hydrolyzed silane coupling agent (Examples 1 to 9) was the case of using the one not hydrolyzing (Examples 10 and 11). ), The adhesiveness was found to be better. From the results of Example 7, it was found that the production method of the present invention can provide good adhesion even on the surface of the copper foil that has been oxidized at high temperature. On the other hand, when the silane coupling agent is not used (Comparative Example 1) or when the concentration of the silane coupling agent in the treatment liquid is low and the coupling agent treatment is insufficient (Comparative Example 2). In both cases, the adhesion was insufficient, and particularly the adhesion was poor during the solder heat resistance test after moisture absorption.

[0068]

According to the manufacturing method of the present invention, by treating the metal surface with a silane coupling agent, the adhesion can be improved without lowering the conductivity, and especially during the solder heat resistance test after absorbing moisture. It is possible to obtain an electronic circuit board that maintains high adhesion. Therefore, by the manufacturing method of the present invention, it is possible to easily and stably form an electromagnetic wave shield layer having extremely high reliability and great effect on the circuit board. Further, it is possible to form a highly reliable wiring on the substrate, and these effects are extremely large industrially.

[Brief description of drawings]

[Figure 1] Figure 1 is a glass / epoxy resin substrate (CEM-3)
It is sectional drawing of the printed circuit board which produced the circuit using.

[Explanation of symbols]

 1 glass / epoxy substrate 2 signal line pattern 3 signal land 4 power supply pattern 5 insulating layer (internal) 6 printed circuit 7 insulating layer (external)

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location // C07F 7/02 A 8018-4H H01B 1/20 Z 7244-5G

Claims (5)

[Claims] 1. A method for manufacturing an electronic circuit board, comprising applying or printing a conductive paste on a metal surface of a substrate and then curing the conductive paste to form a conductive coating film, after treating the metal surface with a coupling agent in advance. A method for manufacturing an electronic circuit board, which comprises applying or printing a conductive paste. 2. The production method according to claim 1, wherein the coupling agent is a silane coupling agent. 3. The method according to claim 2, wherein the silane coupling agent is represented by the general formula (1). [Chemical 1] In the formulas, A is _{Cl, -OC n H 2n + 1} , -NCO, CH 2
= C (CH ₃₎ hydrolyzable groups selected from -O-; T is H, F, CF _3, amino group, alicyclic epoxy group, an epoxy group, a carboxyl group, a hydroxyl group, a phenol group, a phenyl group, acetal Group, alkyl group, alkoxy group, methacryloxy group, Schiff base, silanol group, thiol group, vinyl group, quaternary ammonium salt, isocyanate group, metal, imidazole group, polyoxyalkylene group;
E is an alkyl group having 1 to 20 carbon atoms; R is O, S, NH,
NR '(R' represents Ar or _{C n H 2n + 1),} OC
Represents O, COO, Ar. f is an integer of 1 to 3,
The f A's may be the same or different, and the (3-f) E's may be the same or different. g is an integer of 0 to 10; h is an integer of 0 or 1; i is an integer of 0 to 10.
However, when A is an NCO group, T is selected from functional groups other than amino group, carboxyl group, hydroxyl group, thiol group and imidazole group. ] 4. The coupling agent according to claim 1, which is partially hydrolyzed in advance.
3. The manufacturing method according to any one of 3. 5. The conductive paste comprises a conductive powder, an organic binder, an additive and a solvent, and the conductive powder comprises a copper powder, a silver powder, a nickel powder, an aluminum powder and a palladium powder. 1 or more, wherein the organic binder is selected from the group consisting of a phenol resin, an amino resin, a xylene resin, and a hydroxystyrene polymer and a derivative thereof.
The method according to any one of claims 1 to 4, which comprises one or more kinds of resins.