JPH05174621A - Conductive composite - Google Patents

Abstract

PURPOSE:To enable direct soldering to be carried out on a conductive curing coating so as to improve conductivity and solidity by making a conductive composite to contain copper powder, thermocuring resin, a hologen compound including a specific compound and a specific group. CONSTITUTION:A conductive compound is made to contain copper powder, thermocuring resin, a compound to be expressed by a formula, and a compound simultaneously having a replaceable or unreplaceable amino group or an alkyl amino group, a hydroxyl group or a hydroxy methyl group in one molecule. However in the formula, R1CO- is an acyl group having the carbon number 1 to 22, R2 is a hydrogen atom or an alkyl group or an alkenyl group having the carbon number 1 to 22 and (n) is an integer of 1 to 10. Epoxy resin, urea resin, melamin resin are used as thermocuring resin. The blending rate of a copper powder and that of thermocuring resin are 65 to 95wt.%, for copper powder and 5 to 35wt.% for resin. As a compound to be expressed is caproyl sarcosine, lauroyl sarcosine are used, and as an aromatic compound, o-, m- or p- amino phenol can be used.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a conductive composition,
More specifically, it relates to a solderable conductive composition which has excellent conductivity and solderability and is extremely useful for printed circuits.

[0002]

2. Description of the Related Art Conventionally, in the field of electronic parts, as a conductive composition for a printed circuit, a conductive composition containing a noble metal such as gold and silver as a main component has been widely used. In particular, silver is frequently used because it has the lowest volume resistivity, has conductivity even when oxidized, and is relatively inexpensive among noble metals.

However, when a printed circuit is formed of a conductive composition containing silver as a main component, for example, when the line spacing of the circuit is narrow and the potential difference is large, a silver migration phenomenon (migration) occurs and the circuit However, there is a drawback that the resistance is increased and the circuit is short-circuited. In recent years, cost reduction has been emphasized in the electronic component industry, and there is a problem in terms of cost because silver is relatively inexpensive.

Therefore, recently, various studies have been made on the development of a conductive composition containing copper as a main component, which has a volume resistivity lower than that of silver and is cheaper than silver. However, since the copper powder in the conductive composition has a large oxidizability, it is necessary to store the conductive composition, form a circuit such as printing and heating, or use the formed circuit. At times, the surface of the copper powder is oxidized, the contact resistance between the copper powder particles increases, and sufficient conductivity cannot be obtained. At the same time, there is a disadvantage that soldering cannot be normally performed.

Therefore, in order to solve the drawbacks of such a copper powder, it has been proposed to add various additives to a conductive composition containing copper as a main component, but the additive itself. There are various physical limitations, and problems arise when performing high-performance soldering. Examples of the additive include
JP-B-52-24936 discloses phosphorous acid or a derivative thereof, JP-B-61-36796 discloses anthracene or a derivative thereof, JP-A-57-55974 discloses a derivative of hydroquinone, and JP-A-57-55974. 61-2113
In Japanese Patent No. 78, unsaturated fatty acids are disclosed in Japanese Patent Publication No. 61-1417
A fatty acid amide is disclosed in JP-A-61-20017.
Higher aliphatic amines are disclosed in JP-A-58-225.
Japanese Patent No. 168 proposes a phenylenediamine derivative. However, known conductive pastes containing these additives usually cannot be soldered directly on the cured coating film. It is necessary to carry out a pretreatment such as chemical treatment for electroless plating, or electrolytic copper plating in a plating solution with the coating film as a cathode. Therefore, direct soldering is possible without the need for these pretreatments,
It is desired to develop a conductive composition which can significantly shorten the soldering process for fixing electronic parts and taking out lead wires and is excellent in economic efficiency.

[0006]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solder directly on a conductive cured coating film, and further, it is excellent in conductivity, robustness and the like and is extremely useful for a printed circuit or the like. It is to provide a possible conductive composition.

[0007]

According to the present invention, (a)
Copper powder, (b) thermosetting resin, and (c) the following general formula 2
(In the formula, (R ₁ ) CO— represents an acyl group having 1 to 22 carbon atoms, R ₂ represents a hydrogen atom or an alkyl group or an alkenyl group having 1 to 22 carbon atoms, and n is an integer of 1 to 10). Represents a compound (hereinafter referred to as compound (c)) and

[0008]

[Chemical 2]

(D) A conductive composition containing an aromatic compound having a substituted or unsubstituted amino group or alkylamino group and a substituted or unsubstituted hydroxyl group or hydroxymethyl group in one molecule at the same time. Provided.

The present invention will be described in more detail below.

The (a) copper powder used in the conductive composition of the present invention is not particularly limited, but for example, reduced copper powder obtained by reducing electrolytic copper powder, cuprous oxide, cupric oxide, etc., Preferable examples include atomized copper powder and crushed metal copper. The particle size of the copper powder is preferably 0.5 to 100 μm, and particularly preferably 0.5 to 30 μm. Particle size is 1
When it exceeds 00 μm, there is a problem in printability, and when it is less than 0.5 μm, the copper powder is likely to be oxidized and the conductivity of the resulting coating film decreases, which is not preferable.

Examples of the thermosetting resin (b) used in the conductive composition of the present invention include epoxy resins, urea resins, melamine resins, phenol resins, unsaturated polyester resins, alkyd resins, allyl resins such as diallyl phthalate, Preferable examples are thermosetting urethane resins and polyimide resins.

In the present invention, (a) the copper powder,
The blending ratio with the (b) thermosetting resin is preferably (a).
It is desirable that the copper powder is 65 to 95% by weight, particularly preferably 75 to 90% by weight, that is, (b) the thermosetting resin is 5 to 35% by weight, particularly preferably 10 to 25% by weight. If the compounding ratio of the (a) copper powder is less than 65% by weight, the specific resistance required for a conductive circuit cannot be obtained, and the content is 95% by weight.
When it exceeds, the printability is deteriorated, which is not preferable.

The compound (c) used in the conductive composition of the present invention can be represented by the above general formula 2, wherein (R ₁ ) CO— is an acyl group having more than 22 carbon atoms and R ₂ is When the alkyl group or alkenyl group having more than 22 carbon atoms or n exceeds 10, it is difficult to produce any of them. Specific examples of the compound (c) include N-acyl sarcosine modified from higher fatty acids such as caproylsarcosine, lauroylsarcosine, myristoylsarcosine, palmitoylsarcosine, stearoylsarcosine, oleoylsarcosine, and behenoylsarcosine. , Or mixed fatty acid sarcosine such as coconut oil fatty acid sarcosine and tall oil fatty acid sarcosine, N-lauroyl-N-methyl-β-alanine, N-oleoyl-N-methyl-β-alanine, N-cocoyl-N-methyl- β-
Alanine, N-caproyl-N-methyl-β-alanine, N-myristoyl-N-methyl-β-alanine, N
Preferable examples include -palmitoyl-N-methyl-β-alanine, N-stearoyl-N-methyl-β-alanine and N-behenoyl-N-methyl-β-alanine. The compounding amount of the compound (c) is preferably 0.5 to 10 parts by weight, particularly preferably 1.5 to 7.5 parts by weight based on 100 parts by weight of the total amount of the copper powder and the thermosetting resin.
Parts by weight. When the content is less than 0.5 parts by weight, various effects due to addition cannot be obtained, and when it exceeds 10 parts by weight, the physical properties of the conductive composition are adversely affected, which is not preferable.

An aromatic compound (d) which is used in the present invention and which simultaneously has a substituted or unsubstituted amino group or alkylamino group and a substituted or unsubstituted hydroxyl group or hydroxymethyl group in one molecule (the following compound (d) Is referred to as a component) that improves the solderability of the conductive composition. Examples of the compound (d) include o-aminophenol; m-aminophenol; p-aminophenol; N,
N, N-dialkyl derivatives such as N-dimethyl-m-aminophenol and N, N-dibutyl-m-aminophenol; N-β-hydroxyethyl derivatives such as N-β-hydroxyethyl-m-aminophenol; N , N-di-
(Β-Hydroxyethyl) derivative; dimethoxy-, such as 3,3′-dimethoxy-4,4′-diaminobiphenyl
Diaminobiphenyl; 3,3'-dihydroxy-4,
Preferred examples include dihydroxy-diaminobiphenyl and the like such as 4′-diaminobiphenyl and the like.

The compounding amount of the compound (d) is preferably 2 to 50 parts by weight, particularly preferably 5 to 30 parts by weight, based on 100 parts by weight of the compound (c). When the compounding amount of the compound (d) is less than 2 parts by weight, the desired effect due to the addition of the compound (d) cannot be obtained, and when it exceeds 50 parts by weight, the physical properties as a conductive composition are obtained. It is not preferable because it adversely affects the

To prepare the conductive composition of the present invention, for example, the (a) copper powder, (b) thermosetting resin, the compound (c) and the compound (d) are mixed and kneaded. Can be obtained by When preparing the composition, it is also possible to add a viscosity modifier such as butyl carbitol, an antifoaming agent, a thickener, an anti-skinning agent, etc., if necessary.

[0018]

Since the conductive composition of the present invention contains copper and a thermosetting resin as main components, it is less costly than a conventional conductive composition containing silver or gold as a main component. Also, since it contains the compound (c) and the compound (d), it can be directly soldered on the cured coating film, and has excellent conductivity even under severe environment of high temperature and high humidity. Can be obtained Therefore, for example, by baking and curing the conductive composition of the present invention on an insulating substrate, it is possible to manufacture a printed circuit or the like having extremely excellent conductivity, heat resistance, moisture resistance, and solderability.

[0019]

The present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

The parts in the examples are parts by weight.

[0021]

Example 1 85 parts of electrolytic copper powder having an average particle size of 8 μm was added to 15 parts of a phenol resin (trade name “BLS-364H” manufactured by Showa Polymer Co., Ltd., nonvolatile content 65%), 100 parts of lauroyl sarcosine, and N. 2.5 parts of a mixture of 20 parts of N-dimethyl-m-aminophenol and 5 parts of butyl carbitol were thoroughly mixed and dispersed. The resulting composition was then placed on a glass-epoxy substrate using a 150 mesh stainless screen to a width of 2 mm and a length of 368.
After printing the resistance value measuring pattern of mm, it was heated for 30 minutes in a constant temperature bath kept at 160 ° C. to be baked and cured. The initial resistance value of the obtained cured sample was measured with a digital multimeter, and the film thickness of the printed circuit was measured to calculate the initial specific resistance value. As a result, the initial specific resistance values were 3.0 × 10 ⁴ Ω · cm, respectively. In order to apply solder to the cured coating film of the obtained printed circuit, after applying rosin flux (product name “NS-366” manufactured by Nippon Superior Co., Ltd.) to the substrate, Sn63 / Pb37 eutectic solder was used. The printed circuit was entirely soldered by immersing it in a molten solder bath at ℃ for 5 seconds. Average thickness of solder coat is 15
was μm. The specific resistance after soldering is 4.0 x
It was 10 to ⁵ Ω · cm. Table 1 shows the type of the compound (c), the solder wettability, the specific resistance value after solder coating, and the weight mixing ratio of the compound (c) and the compound (d).

[0022]

[Examples 2 to 7, Comparative Examples 1 to 3] Examples 2 to 7 and Comparative Examples 1 to 3 were carried out except that 3.5 parts of the compounds shown in Table 1 were used instead of the mixture of lauroyl sarcosine and N, N-dimethyl-m-aminophenol. A composition was prepared in the same manner as in Example 1 and each measurement was performed. The results are shown in Table 1.

[0023]

[Table 1]

Claims (1)

[Claims] 1. (a) Copper powder, (b) Thermosetting resin,
(C) The following general formula 1 (in the formula, (R ₁ ) CO— represents an acyl group having 1 to 22 carbon atoms, and R ₂ represents a hydrogen atom or an alkyl group or alkenyl group having 1 to 22 carbon atoms. N is an integer of 1 to 10) and a compound represented by the following formula: (D) A conductive composition containing an aromatic compound having at least one substituted or unsubstituted amino group or alkylamino group and a substituted or unsubstituted hydroxyl group or hydroxymethyl group in one molecule.