JPH11345517A - Anisotropic conductive adhesive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermosetting pasted anisotropic conductive adhesive solving the problem of decrease in insulation between adjacent circuits when making an anisotropic electrical connection between electronic parts. SOLUTION: A thermosetting anisotropic adhesive mixed with conductive fillers and nonconductive fillers contains the nonconductive fillers by 30% or more of the nonconductive fillers in number, the average particle diameter of the nonconductive fillers being greater than that of the conductive fillers. The elastic modulus of the nonconductive fillers such as polybutadiene particles, at adhesive curing temperature, is smaller than the elastic modulus of the conductive fillers such as nickel particles at the adhesive curing temperature.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermosetting type electrically conductive adhesive which is used in the form of a paste.
The present invention relates to an anisotropic conductive adhesive suitable for application to anisotropic electrical connection between C and a circuit board.

[0002]

2. Description of the Related Art By bonding an electronic component to a predetermined portion of an electronic component by pressure bonding, a large number of anisotropic conductive materials are used as an adhesive to make a single electrical connection between a plurality of electrodes of the electronic component and corresponding electrodes of the electronic component. Adhesives have been proposed.

A conventional anisotropic conductive adhesive contains a conductive filler dispersed in a paste-like thermosetting insulating resin. However, with the recent increase in the density of circuits, electrical connection has been made. It has become difficult to ensure insulation between adjacent circuits that must not be achieved.

[0004]

That is, in the case of conventional circuit-to-circuit bonding using an anisotropic conductive adhesive, there is a problem that conductive fillers contained in the adhesive are stochastically connected to lower insulation between adjacent circuits. was there. For this reason, proposals have been made to cover the surface of the conductive filler with a resin or an inorganic film so as not to easily cause a short circuit even if a mere particle contact occurs.

The present invention has been made in view of the above-mentioned problems in the anisotropic electrical connection of electronic components, and provides a thermosetting paste-like anisotropic conductive adhesive capable of solving the problem of insulation deterioration between adjacent circuits. Is what you do.

[0006]

The paste-like anisotropic conductive adhesive according to the present invention is characterized by containing a conductive filler and a non-conductive filler having a specific particle size, material and compounding amount.

That is, the present invention relates to a thermosetting anisotropic conductive adhesive in which a conductive filler and a nonconductive filler are mixed and mixed, wherein the average particle size of the nonconductive filler is the average particle size of the conductive filler. And the non-conductive filler contains 30% or more of the conductive filler in number, and the elastic modulus of the non-conductive filler at the adhesive curing temperature is smaller than the elastic modulus of the conductive filler at the adhesive curing temperature. It is an anisotropic conductive adhesive characterized by being.

Hereinafter, the present invention will be described in detail.

The non-conductive filler contained in the anisotropic conductive adhesive of the present invention has an average particle size larger than the average particle size of the conductive filler. % Is preferable. When the average particle size of the non-conductive filler is less than the average particle size of the conductive filler, or when the amount of the non-conductive filler is less than 30%, the effect of preventing the decrease in insulation due to aggregation of the conductive particles is insufficient. is there. At the curing temperature of the adhesive, the elastic modulus of the non-conductive filler needs to be smaller than the elastic modulus of the conductive filler. If the elastic modulus of the non-conductive filler is smaller than the elastic modulus of the conductive filler, the contact of the conductive filler is maintained by pressure welding, and if the elastic modulus of the conductive filler is larger than the elasticity of the conductive filler, insufficient conduction occurs in electrode bonding. Could be. Preferred examples of the material of the non-conductive filler include particles of an elastic material such as polybutadiene particles, silicone rubber particles, and cross-linked urethane particles or particles of a synthetic resin.

As the conductive filler contained in the anisotropic conductive adhesive of the present invention, those which have been conventionally used for conductive pastes can be widely used. In particular, for example, silver powder, copper powder, nickel powder, etc. These metal powders are suitable, and these can be used alone or in combination of two or more.

The proportion of the non-conductive filler in terms of the number of non-conductive fillers can be estimated by converting the specific gravity, the average particle size and the weight of the non-conductive filler and the conductive filler. As the resin component having an epoxy group used in the present invention, a generally used epoxy resin can be used as long as it is a polyvalent epoxy resin having two or more epoxy groups in one molecule. Specific examples include novolak resins such as phenol novolak and cresol novolak, polyphenols such as bisphenol A, bisphenol F, resorcin, bishydroxydiphenyl ether, ethylene glycol, neopentyl glycol, glycerin, trimethylolpropane, and polypropylene glycol. Polyhydric alcohols such as, ethylenediamine, triethylenetetramine, polyamino compounds such as aniline, adipic acid, phthalic acid, glycidyl type obtained by reacting a polyvalent carboxy compound such as isophthalic acid and epichlorohydrin or 2-methyl epichlorohydrin Epoxy resin, dicyclopentadiene epoxide,
Examples thereof include aliphatic and alicyclic epoxy resins such as butadiene dimer epoxide, and these can be used alone or in combination of two or more.

The curing component used in the present invention can be used without any particular limitation as long as it has two or more active hydrogens in one molecule. Specific examples, for example, diethylene triamine, triethylene tetramine, metaphenylenediamine, dicyandiamide, polyamino compounds such as polyamidoamine, phthalic anhydride,
Examples include organic acid anhydrides such as methylnadic anhydride, hexahydrophthalic anhydride, and pyromellitic anhydride, and novolak resins such as phenol novolak and cresol novolak, which can be used alone or in combination of two or more. .

[0013]

According to the paste-like anisotropic conductive adhesive of the present invention, the average particle size is larger than the particle size of the conductive filler.
In addition, the non-conductive filler, whose elastic modulus is smaller than the conductive filler at the curing temperature of the adhesive, contains 30% or more of the conductive filler in number. Requirements to be performed without the danger of a short circuit.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments.

EXAMPLE 5 100 parts by weight of a thermosetting resin obtained by mixing a bisphenol A type epoxy resin, a phthalic anhydride and an imidazole modified product, contained 10 parts by weight of 5 μm nickel particles (specific gravity 8.845), 3 parts by weight of 7 μm polybutadiene particles (specific gravity: 1.25) were added to obtain a paste-like anisotropic conductive adhesive. The reduced particle number ratio is 10: 7.7 (conductive filler: non-conductive filler).

This adhesive is applied to an electrode having a width of 80 μm and an electrode interval of 60 μm.
applied to a flexible substrate patterned with μm
Another flexible substrate formed in the same pattern was stacked and pressed at 150 ° C. for 100 seconds at 45 kg / cm ² , and then the conduction resistance between the opposing electrodes and the insulation resistance between adjacent electrodes were measured.

Comparative Example 1 To 100 parts by weight of the thermosetting resin used in the examples, 10 parts by weight of 5 μm nickel particles (specific gravity: 8.845) and 0.5 part by weight of 7 μm polybutadiene particles (specific gravity: 1.25) were added. Thus, a paste-like anisotropic conductive adhesive was obtained. The converted particle ratio is 10:
1.3 (conductive filler: non-conductive filler).

This adhesive was applied to an electrode having a width of 80 μm as in the embodiment.
m, coated on a flexible substrate patterned with an electrode spacing of 60 μm, and another flexible substrate made with the same pattern is overlaid at 150 ° C., 100 seconds, 45 kg / cm
After pressure bonding in step ² , the conduction resistance between the opposing electrodes and the insulation resistance between adjacent electrodes were measured.

Comparative Example 2 10 parts by weight of 5 μm nickel particles (specific gravity 8.845) and 10 parts by weight of 7 μm glass particles (specific gravity 3.3) were added to 100 parts by weight of the thermosetting resin used in the examples. Thus, a paste-like anisotropic conductive adhesive was obtained. The reduced particle number ratio is 10: 7.9 (conductive filler: non-conductive filler).

This adhesive was applied to an electrode having an electrode width of 80 μm as in the embodiment.
m, coated on a flexible substrate patterned with an electrode spacing of 60 μm, and another flexible substrate made with the same pattern is overlaid at 150 ° C., 100 seconds, 45 kg / cm
After pressure bonding in step ² , the conduction resistance between the opposing electrodes and the insulation resistance between adjacent electrodes were measured.

Table 1 shows the measurement results of the conduction resistance between the counter electrodes and the insulation resistance between the adjacent electrodes in Examples and Comparative Examples 1 and 2.
However, it was confirmed that the results of the present invention were excellent.

[0022]

[Table 1]

[0023]

As is apparent from the above description and Table 1, the anisotropic conductive adhesive of the present invention satisfies the values of the connection resistance and the insulation resistance.
The circuit connection of the fine electrode pattern can be performed without danger of a short circuit between adjacent electrodes, and it can be adapted to a high-density circuit.

Claims (2)

[Claims] 1. A thermosetting anisotropic conductive adhesive in which a conductive filler and a non-conductive filler are mixed and mixed,
The average particle size of the non-conductive filler is larger than the average particle size of the conductive filler, and the non-conductive filler contains at least 30% of the conductive filler in number, and the elasticity of the non-conductive filler at the adhesive curing temperature. An anisotropic conductive adhesive, wherein the modulus is lower than the elastic modulus of the conductive filler at the temperature at which the adhesive is cured. 2. The anisotropic conductive adhesive according to claim 1, wherein the conductive filler is metal particles and the non-conductive filler is an elastic or synthetic resin particle.