JPH0625613A - Conductive adhesive composition - Google Patents

Abstract

PURPOSE:To obtain a conductive adhesive compsn. which can easily be produced and is excellent in storage stability by compounding an alpha-cyanoacrylate with a conductive material comprising an electrolytic silver powder obtd. by the electrolytic method. CONSTITUTION:This compsn. is obtd. by compounding an alpha-cyanoacrylate with an electrolytic silver powder produced by the electrolytic method. A usable alpha-cyanoacrylate is one which is widely used for preparing a so-called instant adhesive and represented by the formula (wherein R is 1-10C alkyl, alkenyl, alkoxyalkyl, tetrahydrofurfuryl, phenyl, cyclohexyl, etc.). The silver powder has a particle size of pref. 150mum or lower, still pref. 63mum or lower; a particle size larger than 150mum is not pref. since it causes the sedimentation and separation of the powder in the alpha-cyanoacrylate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive adhesive composition obtained by adding a conductive substance to α-cyanoacrylate.

[0002]

2. Description of the Related Art Generally, as an adhesive for adhering electronic parts to each other and giving conductivity between the adhered parts, α-
It is known that a conductive additive such as metal powder is added to cyanoacrylate. However, the adhesive containing the additive thus deteriorated significantly and was difficult to store for a long period of time.

Therefore, conventionally, as an additive to be added to such an adhesive, one using metal powder pretreated with an acidic substance (for example, Japanese Patent Publication No. 63-2894).
No. 7, Japanese Patent Application Laid-Open No. 60-1187776), those in which an acidic polymerization inhibiting substance is added together with metal powder (see, for example, Japanese Patent Application Laid-Open No. 62-89780), and the like.

[0004]

However, in the case of the above-mentioned conventional adhesive composition, the following disadvantages occur.

That is, in the case of using the metal powder pretreated with an acidic substance, since the metal powder is processed, the number of manufacturing steps increases, the cost increases, and the manufacturing process becomes long.

Further, in the case of adding an acidic polymerization inhibiting substance, it is necessary to strictly control the addition amount of the acidic polymerization inhibiting substance in the unit of ppm, resulting in a troublesome preparation.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a conductive adhesive composition which can be easily manufactured and has excellent storage stability.

[0008]

The electroconductive adhesive composition of the present invention comprises α-cyanoacrylate to which electrolytic silver powder produced by electrolysis is added as an electroconductive substance.

As the α-cyanoacrylate, those widely used as so-called instant adhesives can be used as shown in the following general chemical formula.

[0010]

[Chemical 1] In the chemical formula ₁ , R is a C ₁ -C ₁₆ alkyl group,
It represents an alkenyl group, an alkoxyalkyl group, a tetrahydrofurfuryl group, a phenyl group, a cyclohexyl group, or the like.

Further, the above α-cyanoacrylate includes
Stabilizers such as SO ₂ and hydroquinone are added to maintain stability before addition of electrolytic silver powder, and thickeners such as PMMA and PVAC are added to suppress sedimentation and separation after addition of electrolytic silver powder.

The electrolytic silver powder has a particle size of 150 μm or less, and particularly preferably 63 μm or less. If this particle size exceeds 150 μm, the electrolytic silver powder is not preferable because it precipitates and separates in α-cyanoacrylate. The amount of electrolytic silver powder added is 60 to 100 parts by weight, particularly preferably 70 to 90 parts by weight, based on 100 parts by weight of α-cyanoacrylate. If the addition amount is less than 60 parts by weight, poor conductivity will occur, and if it exceeds 100 parts by weight, the adhesive strength will be insufficient.

As a method for producing this electrolytic silver powder, first, a few amperes of electric current are passed through a few% Ag ₂ SO ₄ solution at room temperature to wash and neutralize the silver powder deposited on the silver plate electrode. After that, dehydrate. Then, the silver powder is crushed, classified, and then dried.

Since the electrolytic silver powder thus obtained is deposited in an acidic solution, a small amount of acid remains even after neutralization. Therefore, when washing and neutralizing the deposited silver powder, a desired acidity can be imparted to the electrolytic silver powder by adjusting the neutralization level to PH5 to 7 according to the purpose.

Further, as shown in FIGS. 1 to 3, the electrolytic silver powder obtained by the electrolysis method (see FIG. 1) is a copper powder obtained by the same electrolysis method (see FIG. 2) or the reduction method. Compared with the silver powder (see Fig. 3) obtained by the method, the unit surface area is dendritic, and the particle surface is smooth. Therefore, it is easy to remove the attached water on the particle surface by vacuum drying, and it is difficult for water to remain. Does not increase activity.

[0016]

The conductive adhesive composition of the present invention exhibits excellent storage stability by adding electrolytic silver powder produced by electrolysis as a conductive substance to α-cyanoacrylate.

[0017]

EXAMPLES Examples according to the present invention and comparative examples serving as comparative controls will be shown below to clarify the reason why the present invention is excellent.

[0018]

[Examples 1 to 13 and Comparative Examples 1 to 5] A predetermined amount of metal powder having various particle sizes was added to and mixed with 10 g of commercially available α-cyanoacrylate having various viscosities, and paper of set time, volume resistance, and copper wiring was used. The tensile shear strength between the phenol substrates was measured. Further, this composition was placed in 20 ml of polyvin and sealed, placed in a hot air circulation type constant temperature bath at 70 ° C., and the number of days until solidification was measured to test the storage stability.

The conditions of each composition are shown in Table 1, and the test results thereof are shown in Table 2.

[0020]

[Table 1]

[0021]

[Table 2] In the above Examples and Comparative Examples, α-cyanoacrylate used was Sekisui Aiko Co., Ltd.,
The metal powder used was made by Fukuda Metal Foil & Powder Co., Ltd.

Further, the amount of the metal powder blended is the weight part of the metal powder when 10 g of α-cyanoacrylate is 100.

Further, the set time and the tensile shear strength were measured according to JIS K 6861 (Testing method for cyanoacrylate adhesives). Further, the volume resistance was measured according to ASTM-D-2739.

[0024]

As described above, according to the present invention, α
-By adding electrolytic silver powder produced by electrolysis as a conductive substance to cyanoacrylate, a conductive adhesive having excellent storage stability can be easily obtained.

[Brief description of drawings]

FIG. 1 shows an electrolytic silver powder obtained by an electrolysis method 2.
It is a 00 times enlarged electron micrograph.

FIG. 2 shows electrolytic copper powder obtained by electrolysis method 2
It is a 000 times magnified electron micrograph.

FIG. 3 shows electrolytic copper powder obtained by electrolysis method 2
It is a 00 times enlarged electron micrograph.

FIG. 4 shows an electrolytic copper powder obtained by an electrolysis method 2
It is a 000 times magnified electron micrograph.

FIG. 5 is a 1000 × magnified electron micrograph showing silver powder obtained by the reduction method.

FIG. 6 is a 5000 × magnified electron micrograph showing silver powder obtained by the reduction method.

[Procedure amendment]

[Submission date] November 2, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a photograph of a grain structure, specifically, a 200 × magnified electron micrograph showing electrolytic silver powder obtained by an electrolysis method.

[Figure 2] This Figure is a photograph of the grain structure, in particular, a 2000 magnification electron micrograph showing an electrolytic silver powder obtained by the electrolysis method.

FIG. 3 is a photograph of a grain structure, specifically, a 200 × magnified electron microscope photograph showing electrolytic copper powder obtained by an electrolysis method.

FIG. 4 is a photograph of a particle structure, specifically, a 2000 × magnified electron microscope photograph showing electrolytic copper powder obtained by an electrolysis method.

FIG. 5 is a photograph of a grain structure, specifically, a 1000 × magnification electron microscope photograph showing silver powder obtained by the reduction method.

FIG. 6 is a photograph of a grain structure, specifically, a 5000 times magnified electron microscope photograph showing silver powder obtained by the reduction method.

Claims (1)

[Claims] 1. A conductive adhesive composition comprising α-cyanoacrylate to which electrolytic silver powder produced by an electrolysis method is added as a conductive substance.