JPH09282940A - Conductive copper paste composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve excellent conductivity and enhance retentiveness and a rapid curing property by using copper powder, a thermosetting resin, a polyvalent phenol monomer and acid anhydride or ester expressed by a predetermined chemical formula. SOLUTION: A conductive copper paste composition is composed of copper powder, a thermosetting resin, a polyvalent phenol monomer and acid anhydride or ester expressed by a predetermined chemical formula. In this case, a resol type phenol resin is used as the thermosetting resin; 2,2-dimethylpropionic anhydride or the like, as acid anhydride expressed by the predetermined chemical formula; and butyric acid, as ester expressed by the predetermined chemical formula. Consequently, a printed circuit board such as a paper base board or glass base board is subjected to screen printing, followed by heating and curing, thereby applying excellent conductivity. Furthermore, it is possible to achieve excellent retentiveness and rapid curing in the curing process.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive copper paste composition and, more particularly, to screen printing on through holes of a printed circuit board such as a paper-based phenolic resin board or a glass fiber-based epoxy resin board. rear,
The present invention relates to a conductive copper paste composition having good substrate adhesion and good conductivity when heated and cured.

[0002]

2. Description of the Related Art Conductive copper paste (hereinafter, referred to as copper paste) has attracted attention as a conductor for circuit boards in place of expensive conductive silver paste (hereinafter, referred to as silver paste). As a copper paste, a paste composition in which a thermosetting resin such as phenol resin is used as a binder in a copper powder is known, but since copper is essentially more easily oxidized than silver, the copper paste has a long-term conductivity. There is a problem in terms of maintaining. That is, copper is oxidized in the process of hardening after screen printing. As a measure for preventing such oxidation, for example, the method described in JP-A-61-3154 or JP-A-63-286477. It has been known. Furthermore, in the case of copper paste, if the copper powders do not sufficiently contact each other, they do not conduct, and it is difficult to immediately become a silver paste substitute. In order to sufficiently bring the copper powders into contact with each other, attempts have been made to use a thermosetting resin such as a resole having a large curing shrinkage as a binder. In addition, in order to effectively exhibit its binding force, Japanese Patent Laid-Open No. 5-179
Heterocyclic compounds have also been added as disclosed in Japanese Patent Publication No. 164/164. However, the basic component delays the curing rate of the resin, and the curing of the copper paste may be insufficient depending on the curing conditions. On the other hand, the acid has a curing-accelerating action, but has a great adverse effect on the preservability of the copper paste.

[0003]

DISCLOSURE OF INVENTION Problems to be Solved by the Invention In the present invention, as a result of improving and studying the drawbacks of conventional copper pastes, copper powder, thermosetting resin, polyhydric phenol monomer, specific acid anhydride or ester are essential components. It was found that, by setting the above, the storage stability of the copper paste is compatible with the rapid curing. The object of the present invention is that screen printing is possible, and it has both good conductivity as silver paste and metal migration resistance that cannot be obtained with silver paste, and it can be quickly cured in the curing step after printing. It is to provide a pitch-compatible copper paste composition.

[0004]

The present invention provides a conductive copper paste composition comprising a copper powder, a thermosetting resin, a polyhydric phenol monomer, an acid anhydride represented by Formula 1 or an ester represented by Formula 2, and a solvent. Things are related.

Embedded image n and m are integers of 3 or more

In the present invention, as the copper powder, commercially available products can be used as they are, and any shape such as scale, dendritic or spherical can be used, and atomized copper powder, ground copper powder, electrolytic copper powder. Any of these can be used. The particle size is not particularly limited, but in the case of a copper paste having good screen printing characteristics, it is desirable that the powder is as fine as possible.

In the present invention, the thermosetting resin used as the binder may be epoxy resin, melamine resin, unsaturated polyester resin, phenol resin or the like, and is not particularly limited, but phenol and formaldehyde are used as alkali catalysts. The so-called resol type phenol resin reacted below is preferable in terms of heat resistance and adhesion to copper. In the present invention, as the polyhydric phenol monomer used for preventing the oxidation of copper, catechol, resorcin, hydroquinone and the like can all be used, but hydroquinone is particularly preferable.

The amount of the thermosetting resin compounded is preferably 8 to 20 parts by weight with respect to 100 parts by weight of the copper powder. If the amount is less than 8 parts by weight, a sufficient amount of the resin cannot be obtained in many cases, and a sufficient bonding force cannot be obtained. If the amount is more than 20 parts by weight, the conductivity decreases. The addition amount of the polyhydric phenol monomer is preferably 3 to 10 parts by weight with respect to 100 parts by weight of the copper powder, and if less than 3 parts by weight, the effect of preventing the oxidation of the copper powder is small. And other various performances.

In the present invention, it is preferable to use an imidazole compound. As the imidazole compound, one or more imidazole compounds having a long-chain aliphatic hydrocarbon such as N, N '-{2-methylimidazolyl- (1) -ethyl} -eicosanedioyldiamide are used. This imidazole compound buffers the curing shrinkage of the resin itself and the internal shrinkage caused by the volatilization of the solvent, and prevents the cured product in the through-hole and cracks due to thermal stress such as solder heat resistance after curing and can maintain reliability. Further, the imidazole compound forms a chelate compound with the copper powder, whereby the adhesion is improved, the contact between the copper powders becomes dense, and good electrical conductivity is obtained.

In the present invention, the acid anhydride of the chemical formula 1 or the ester of the chemical formula 2 protects the site of the acid anhydride bond or the ester bond from a bulky group in the molecule and prevents the decomposition easily. When using the copper paste of
Storability at room temperature is stable, and when cured by heating,
It quickly decomposes and exhibits the effect of promoting the curing of the resin. Preferred acid anhydrides include 2,2-dimethylpropionic acid anhydride, and preferred esters include butyl butyrate, isopentyl butyrate, isobutyl isobutyrate, isopentyl isovalerate, and butyl stearate. In the chemical formula 1 or 2, if the value of n is too large, the action as an acid after decomposition becomes weak. Therefore, the value of n is preferably 20 or less.

The solvent used in the present invention is, for example, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, propylene glycol monomethyl ether, dipropylene glycol monomethyl ether, propylene glycol monopropyl ether. , Dipropylene glycol monopropyl ether, ethylene glycol monoisopropyl ether, diethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether,
Diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, propylene glycol monobutyl ether, dipropylene glycol monobutyl ether, ethylene glycol monoisobutyl ether, diethylene glycol monoisobutyl ether,
Ethylene glycol monohexyl ether, diethylene glycol monohexyl ether, ethylene glycol mono 2-ethylhexyl ether, ethylene glycol monoallyl ether, ethylene glycol monophenyl ether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, triethylene glycol dimethyl ether , And glycol ether inducers such as these ester compounds are used in one kind or in a mixture of two or more kinds.

Although various methods can be applied to the method for producing the copper paste, it is general that the structural components are mixed and then kneaded by a three-roll mill. Further, various antioxidants, dispersants, solvents and the like can be added to the composition as needed.

[0012]

EXAMPLES The present invention will be described below with reference to examples. A resole type phenol resin was used as a thermosetting resin, and kneaded with a three-roll mill according to the mixing ratio shown in Table 1 to obtain a copper paste composition. The obtained copper paste was screen-printed on a paper-based phenolic resin laminate and then cured in an oven at 120 ° C. for 10 minutes. The specific resistance values of these test pieces were measured.

[0013]

[Table 1] Ester 1: butyl butyrate, ester 2: isopentyl butyrate, ester 3: isobutyl isobutyrate, ester 4: isopentyl isovalerate, ester 5: butyl stearate,

[0014]

EFFECT OF THE INVENTION The copper paste composition according to the present invention gives good conductivity by screen printing on a printed circuit board such as a paper-based substrate or a glass-based substrate, followed by heating and curing. It is very useful as a copper paste because it has excellent storability and quickly cures during the curing process.

Claims (3)

[Claims] 1. A copper powder, a thermosetting resin, a polyhydric phenol monomer, an acid anhydride represented by the chemical formula 1 or a chemical formula 2.
A conductive copper paste composition comprising an ester and a solvent represented by. Embedded image n and m are integers of 3 or more 2. The acid anhydride represented by the chemical formula 1 is 2,2
-The conductive copper paste composition according to claim 1, which is dimethylpropionic anhydride. 3. The ester represented by the chemical formula 2 is butyl butyrate, isopentyl butyrate, isobutyl isobutyrate, isopentyl isovalerate, and butyl stearate.
The conductive copper paste composition as described in the above.