JP3316745B2 - Conductive paint - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a conductive paint, and more particularly, to a conductive paint in which metallic copper powder is dispersed in a phenol resin mixture.

[0002]

2. Description of the Related Art Printed circuit boards are used as materials for mounting ICs, MSIs, LSIs and the like. As a method of electrically connecting the copper foil circuits on both sides of this printed circuit board, a through hole is provided in an insulating layer between the copper foil circuits on both sides, and a through hole provided with a conductive material is formed in this. It is common. At that time, as one of means for disposing a conductive material, a conductive silver paint (hereinafter, referred to as silver paste) is disposed by a screen printing method or the like.

[0003] However, silver paste is expensive, and
There is also the problem of silver migration.

[0004] For this reason, the present inventors have provided a conductive copper paint which is inexpensive and has little migration problem as an alternative to the silver paste (see Japanese Patent Application Laid-Open No. 6-108006).

[0005]

However, it has been found that when a through hole is formed with the above-mentioned conductive paint, there is a problem in the thermal shock characteristics after moisture absorption. That is, it was found that there was a large increase in resistance in the soldering step after the moisture resistance test, and there was a possibility that poor conductivity of the product occurred.

[0006] The present invention has been made in view of the above,
An object of the present invention is to provide a conductive paint having excellent conductivity and adhesion, and having a small resistance change in thermal shock characteristics after moisture absorption.

[0007]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors have conducted intensive studies, and as a result, have removed the hygroscopic chelating layer forming agent, and have succeeded in removing the amino group-containing coupling agent and the hydrophobic agent. It has been found that the above problems can be solved by using a specific amount of 1,2-N-acyl-N-methyleneethylenediamine compound of the present invention, and the present invention has been completed.

That is, the conductive paint of the present invention comprises (A) 100 parts by weight of metallic copper powder,
(B) 5 to 33 parts by weight of a resole type phenol resin,
(C) 0.5 to 3.5 parts by weight of an amino compound acting as a reducing agent , (D) 0.5 to 4 parts by weight of an amino group-containing coupling agent, and (E) 1,2-N-acyl-N- It is assumed that the composition contains 0.5 to 4 parts by weight of a methylene ethylenediamine compound.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION (A) Metallic copper powder The metallic copper powder used in the present invention may have any shape such as flake, dendrite, sphere, and irregular shape. Particle size is 100
μm or less, particularly preferably 1 to 30 μm. Particles having a particle size of less than 1 μm are not preferred because they are easily oxidized and the conductivity of the obtained coating film (coating film) is reduced.

(B) Resol-type phenol resin The structure of the resol-type phenol resin used in the present invention is not particularly limited, and it can be used with or without modification. The molecular weight is not particularly limited.

The amount of the resole resin added is 100
It is in the range of 5 to 33 parts by weight, preferably 9 to 20 parts by weight with respect to parts by weight. If the amount is less than 5 parts by weight, the metallic copper powder is not sufficiently bound, the resulting coating film becomes brittle, and the conductivity decreases. If the amount exceeds 33 parts by weight, the conductivity will decrease.

(C) Amino compound acting as reducing agent The amino compound used in the present invention is a compound acting as a reducing agent.
As long, but the kind of that is not particularly limited, and specific examples include aniline, diphenylamine, phenylenediamine, diaminonaphthalene, anisidine, aminophenol, diaminophenol, acetylamino phenol, amino benzoic acid, N, N- And diphenylbenzidine. These amino compounds are
The seeds may be used alone or in combination of two or more.

The compounding amount of the amino compound is 100 parts of metallic copper powder.
The amount is 0.5 to 3.5 parts by weight, preferably 1 to 3 parts by weight with respect to parts by weight. If the amount is less than 0.5 part by weight, the effect of improving the conductivity of the coating film cannot be sufficiently obtained.
Even if the amount exceeds 5 parts by weight, no further improvement in conductivity is observed.

[0014] These amino compounds-out work as a reducing agent together act as a conductivity enhancing agent, to prevent oxidation of the metallic copper powder, which contributes to the maintenance of conductivity.

(D) Amino Group-Containing Coupling Agent The type of amino group-containing coupling agent is not particularly limited, but specific examples include isopropyl-4-aminobenzenesulfonyldi (dodecylbenzenesulfonyl) titanate and isopropyldi (4 -Aminobenzoyl) isostearoyl titanate, isopropyl tri (N, N-dimethylethylamino) titanate, isopropyl tri (N-ethylaminoethylamino) titanate, isopropyl trianthranyl titanate, 4-aminobenzenesulfonyl dodecylbenzenesulfonyloxy acetate titanate, 4-aminobenzoylisostearoyloxyacetate titanate, 4-aminobenzenesulfonyldodecylbenzenesulfonylethylene titanate, 4-aminobenzoyl Isostearoyl Le ethylene titanate, Jian anthranilate ethylene titanate, .gamma.
(2-aminoethyl) aminopropyltrimethoxysilane, γ- (2-aminoethyl) aminopropylmethyldimethoxysilane, hexamethyldisilazane, γ-anilinopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, and the like. Can be One of these amino group-containing coupling agents may be used alone, or two or more thereof may be used in combination.

The amount of the amino group-containing coupling agent is 0.5 to 4 parts by weight based on 100 parts by weight of metallic copper powder. If the added amount is less than 0.5 part by weight, the conductivity is lowered, and if it exceeds 4 parts by weight, the conductivity is also lowered. The amino group-containing coupling agent may be added directly to the conductive paint, or may be mixed with metallic copper powder and used to coat the surface.

These amino group-containing coupling agents cover the surface of the metallic copper powder, thereby promoting the fine dispersion of the metallic copper powder in the resin mixture, thereby improving the conductivity of the conductive paint and improving the quality. Is considered to be stabilized.

(E) 1,2-N-acyl-N-methylene
Ethylenediamine compound 1,2-N-acyl-N-methyleneethylenediamine compound is a novel compound disclosed in Japanese Patent Application No. 9-105588 and has a structure represented by the following formula (I).

[0019]

Embedded image .

R in the above formula (I) represents a hydrogen atom or a hydrocarbon group. The hydrocarbon group includes both an aliphatic hydrocarbon group and an aromatic hydrocarbon group, and the type thereof is not particularly limited, but may be an alkyl group such as a methyl group, an ethyl group, or a propyl group, or a cycloalkyl group such as a cyclopentyl group or a cyclohexyl group. An aralkyl group such as an alkyl group, a benzyl group and a phenethyl group can be exemplified.

The compounding amount of this compound is 0.5 to 4 parts by weight, preferably 0.8 to 4 parts by weight per 100 parts by weight of metallic copper powder.
3.5 parts by weight. This compound contributes to the improvement of the conductivity of the coating film, etc., even when the compounding amount is less than 0.5 part by weight,
When the amount exceeds 4 parts by weight, the effect of improving conductivity tends to be insufficient.

[0022] Other conductive coating of the present invention may be to adjust the viscosity, suitably using normal organic solvent.

Examples of the organic solvent include, for example, methyl cellosolve, cellosolve, butyl cellosolve, 3-methoxy-3-methyl-1-butanol, methyl cellosolve acetate, cellosolve acetate, butyl cellosolve acetate, 3-methoxy-3-methyl Known solvents such as -1-butyl acetate, methyl carbitol, carbitol, butyl carbitol, methyl carbitol acetate, carbitol acetate, butyl carbitol acetate, and dibasic acid ester are exemplified.

[0024]

EXAMPLES The present invention will be described more specifically with reference to the following examples, but the present invention is not limited to these examples.

Examples 1 to 5, Comparative Examples 1 to 7 Resole-type phenol resin, aminophenol, amino group-containing coupling agent, 1,2- N-dodecanoic-N-methyleneethylenediamine was blended in the proportions (parts by weight) shown in Tables 1 and 2, respectively, and DBE was used as a solvent.
A mixed solvent of (dibasic acid ester DuPont) and methyl carbitol was added, and the mixture was kneaded with a triaxial roll for 20 minutes, and the viscosity was 30 to 30 with a viscometer VT-04 manufactured by Rion.
The conductive paint was obtained by adjusting the pressure to be within the range of 50 dPa · s.

The following were used as the resol type phenol resin and the amino group-containing coupling agent.

1: Resol type phenol resin a-Regitop PL4348 (manufactured by Gunei Chemical) 2: Resol type phenol resin b-Nicanol PR14
40 (xylene-modified phenol, manufactured by Mitsubishi Gas Chemical) 3: amino group-containing coupling agent a-KBM602 (manufactured by Shin-Etsu Chemical) 4: amino group-containing coupling agent b-KBM573 (manufactured by Shin-Etsu Chemical)

[0028]

[Table 1] .

[0029]

[Table 2] .

The properties of the conductive paints of these Examples and Comparative Examples were evaluated as follows.

FIG. 1 is a sectional view of a resistance value test piece, FIG. 2A is a plan view of the test piece of FIG. 1, and FIG. 1 and 2, reference numeral 32 indicates a paper phenol substrate, 33 indicates a through hole, and 34 and 34 'indicate copper foils, respectively.

As shown in FIG. 1, each of the conductive paints shown in Tables 1 and 2 was screen-printed using a 120-mesh tetron screen to form a through-hole 33 (with a hole diameter of 0 mm) of a 1.6 mm-thick paper phenol substrate 32. 0.5 mm). This is heated to 70 ° C ± 20 using an air oven.
C. for 2 hours to temporarily dry the coating film b.
Cured at 300C for 30 minutes.

As shown in FIG. 2, the through holes 33 are
Twenty holes form a row in the horizontal direction at a pitch of 1.3 mm to 2.0 mm, and such rows A to K are 1.3 mm to 2.0 mm.
The pitch is provided. On the front side of the substrate 32, each of two adjacent through holes 33 is
4 (see FIG. 3A) and the two through holes 33, 33 not connected by the copper foil 34 on the front side are connected by the copper foil 34 'on the back side (see FIG. 2B). .

In the test piece having such a configuration,
As the evaluation of the conductivity of the coating film b, the end portions 41 to 42, 42 to
The series resistance of 20 holes between 43 and 43 to 44 was measured and divided by 20 to obtain the resistance per through hole.

The thermal shock characteristics after moisture absorption were evaluated as follows.

That is, the resistance value of the substrate obtained by printing and curing the conductive paint as described above was measured at 40 ° C. and 90%
After being left for 96 hours in a humidity atmosphere of RH, the resistance value after dipping twice in a solder bath at 260 ° C. was measured, and the resistance change rate was obtained.

Next, as shown in FIG. 3, the coating film b on the through-hole copper foil land 34 was divided into crosses by a knife (S line) as shown in FIG. The evaluation was performed based on the number of coating films b remaining on the lands 34. For example, 0/4 if all 4 divisions are peeled off, 1/4 if one is left
And

The evaluation results are shown in Tables 1 and 2.

As is evident from the results shown in these tables, in the conductive paints of the examples, since the compounding amounts of the respective compounding materials are appropriately combined, the conductive properties and the thermal shock characteristics after moisture absorption are obtained. Excellent in all of the adhesiveness on the copper foil.

On the other hand, in each comparative example, the compounding amount of any one of the components did not satisfy the requirements of the present invention. It turns out that it is inferior.

[0041]

The conductive paint of the present invention has excellent conductivity and adhesion, and has little change in resistance in thermal shock characteristics after moisture absorption. Therefore, it becomes possible to obtain a through-hole at a low cost without worrying about migration.

[Brief description of the drawings]

FIG. 1 is a sectional view of a resistance value test piece.

FIG. 2A is a plan view of the test piece of FIG. 1, and FIG.
FIG.

FIG. 3 is a conductive paint film b of a through-hole copper foil land 34
FIG. 4 is an explanatory view showing a method of an adhesion test of the present invention.

[Description of Signs] b: conductive paint (coating film) 33: through-hole 34, 34 ': copper foil

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-6-157946 (JP, A) JP-A-5-29739 (JP, A) European Patent Application Publication 803499 (EP, A1) (58) Field (Int.Cl. ⁷ , DB name) C09D 161/00-161/34 C09D 5/24 C09D 7/12 H01B 1/20-1/24

Claims (1)

(57) [Claims] (B) 5 to 33 parts by weight of a resole phenolic resin, (C) 0.5 to 3.5 parts by weight of an amino compound acting as a reducing agent , D) 0.5-4 parts by weight of an amino group-containing coupling agent,
And (E) a conductive paint containing 0.5 to 4 parts by weight of a 1,2-N-acyl-N-methyleneethylenediamine compound.