JPH11209715A - Electroconductive adhesive - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an elecroconductive adhesive that has both high adhesion and good repairing properties and shows high electroconductivity by containing a specific thermosetting resin, a phenoxy resin, a specific epoxy resin and an electroconductive filler. SOLUTION: The objective adhesive contains (A) a thermosetting resin as a mixture of (i) a phenolic resin such as a novolak type phenolic resin with, when necessary, (ii) an epoxy resin such as a bisphenol-A type epoxy resin, (B) a phenoxy resin, (C) a liquid epoxy compound that has a viscosity at 25 deg.C of preferably 1-200 cP, more preferably 1-100 cP, particularly 1-50 cP and bears at least one glycidyl group in one molecule, and (D) 65-90 wt.% of an electroconductive filler. In a preferred embodiment, the contents of the organic binders [the components A, B and C except the filler (the component D)] are 5-50 wt.%, 1-20 wt.% and 10-80 wt.%, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive adhesive used for assembling ICs, LSIs, other semiconductor elements, and various electric and electronic parts, or for bonding to a substrate.

[0002]

2. Description of the Related Art Conventionally, Sn-Pb eutectic solders have been widely used for assembling ICs, LSIs, other semiconductor elements and various electric and electronic parts or bonding them to substrates, because of their excellent conductivity and high reliability. It has been. On the other hand, in recent years, semiconductor devices such as LSIs have been reduced in size and increased in function as devices have become lighter and thinner, and a large number of connection terminals having a fine pitch in which the widths and intervals of connection terminals have been reduced have become necessary. However,
The solder has a risk of causing a bridging phenomenon at the time of soldering when the fine pitch of the connection terminal advances, and there is a limit in responding to the fine pitch. In addition, since the solder has a high reflow temperature, there are restrictions on the members that can be joined, and the fact that it contains lead has been a problem from the viewpoint of environmental protection. Therefore, a conductive adhesive such as an epoxy resin-silver type is used as a connection material instead of the solder.

However, recent conductive adhesives have not only the conductivity and adhesiveness of fine circuits, but also parts that are once bonded at the time of adhesive manufacturing are defective or have insufficient circuit conductivity. In such a case, there is a demand for a repair property which is such a property that the member at that portion can be peeled off using a known means, an inconvenient portion can be improved, and bonding can be performed again accurately. This is a property required when connecting a complicated circuit board.

A conductive adhesive using only a thermosetting resin as a binder, such as the epoxy resin-silver-based conductive adhesive, has high conductivity and strong adhesive strength, but the bonded member is defective. In such a case, the member cannot be removed (repaired). On the other hand, a conductive adhesive using only a thermoplastic resin as a binder is also used, but the conductive adhesive has an advantage that it can be easily repaired by heating or a solvent, but is based on a thermosetting resin. Adhesives with lower or higher adhesive strength than the adhesives used usually have a higher melting point, so that
A high temperature of 0 ° C. or higher is required, and there are problems such as deterioration of a member to be bonded.

[0005] Further, the conductive adhesive is required to have high conductivity and a small rate of change in volume resistivity. If the rate of change of the volume resistivity is large, the element may malfunction, so it is desired that the element be stable for a long period of time. The required value varies depending on the member to which the conductive adhesive is applied. For example, the required adhesive strength is 7 kgf (2 mm
Chip) or more, the volume resistivity is 1 × 10 ⁻³ Ωcm or less, and the heat cycle test (−25 ° C. to 125 ° C.,
It is required that the rate of change of the volume resistivity after 500 cycles at each 30 minutes) is within 20%. A conductive adhesive that satisfies such characteristics and that can be repaired is not known at present.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide both adhesiveness and repairability, which are contradictory properties in conventional conductive adhesives, high conductivity, and stable conductivity for a long period of time. It is to provide a conductive adhesive.

[0007]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, phenoxy resin, low molecular weight epoxy compound, phenol resin or phenol resin as an organic binder of a conductive adhesive. It can be repaired by using a mixture of resin and epoxy resin as an essential component, has sufficient adhesive strength and conductivity to withstand practical use, and finds that the conductivity is stable for a long period of time. Reached.

That is, the present invention provides (1) a conductive adhesive comprising a thermosetting resin, a phenoxy resin, a liquid epoxy compound having at least one glycidyl group in one molecule, and a conductive filler, (2) a conductive adhesive, wherein the thermosetting resin is a phenolic resin or a mixture of a phenolic resin and an epoxy resin;
The content of the phenoxy resin is 1 to 2 of the whole organic binder.
The conductive adhesive according to the above (1), wherein the viscosity of the liquid epoxy compound is 200 cP.
(1) The conductive adhesive according to (1) or (2), wherein the phenol resin is a novolak type phenol resin.
(2) The conductive adhesive according to (3), (5) the conductive resin according to (1), (2), (3) or (4), wherein the epoxy resin is a bisphenol A type epoxy resin. Glue.

Hereinafter, the present invention will be described in detail. The thermosetting resin used in the present invention is a phenol resin alone or a mixture of a phenol resin and an epoxy resin. When a mixture of a phenolic resin and an epoxy resin is used, the mixing ratio varies depending on the type of filler used, but in order to obtain sufficient conductivity, the phenolic resin is 1% by weight or more, preferably 5% by weight of the entire thermosetting resin. % Or more is required.
Especially when using easily oxidizable filler such as copper,
It is preferably at least 50% by weight.

In order to obtain sufficient strength, conductivity and stability of conductivity, a mixture of a phenol resin and an epoxy resin is preferred. When a filler that is easily oxidized such as copper is used, a phenol resin alone is preferable in order to exhibit sufficient conductivity. The thermosetting resin preferably accounts for 5 to 50% by weight of the entire organic binder. If it is less than 5% by weight, it is difficult to obtain a sufficient strength, and if it exceeds 50% by weight, the viscosity increases and the workability deteriorates. More preferably, 1
0 to 40% by weight. In the present invention, the organic binder refers to a resin component excluding a conductive filler contained in a conductive adhesive.

The phenolic resin of the present invention includes a novolak type phenol resin, a resol type phenol resin, an alkylphenol resol resin, a xylene resin modified resol type resin, a rosin modified phenol resin, and the like. In order to obtain a stable cured product, a novolak-type phenol resin is preferable because a volatile component is not generated at the time of curing.

Examples of the epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, (cresol) novolak type epoxy resin, halogenated bisphenol type, resorcinol type, tetrahydroxyphenolethane type, polyalcohol polyglycol type, Glycerin triether type, polyolefin type, epoxidized soybean oil, cyclopentadiene dioxide, vinylcyclohexene dioxide and the like can be mentioned. In order to obtain a cured product having high adhesive strength, a bisphenol A type epoxy resin is particularly preferable.

The liquid epoxy compound having one or more glycidyl groups in one molecule used in the present invention is generally used as a diluent for epoxy resins. By using such a liquid epoxy compound, it is possible to obtain a stable cured product without generation of voids during curing. The viscosity at 25 ° C. of the liquid epoxy compound of the present invention is 1
Those having a cP of 200 cP or less are preferable, more preferably 1 cP or more and 100 cP or less, and particularly preferably 1 cP or less.
It is not less than 50 cP. Viscosity at 25 ° C of 200
A liquid epoxy compound having a cP or less is preferable because a conductive adhesive having an appropriate viscosity can be obtained only by adding a small amount.

Examples of such compounds include phenoxyalkyl monoglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, glycerin diglycidyl ether, N, Examples thereof include N-diglycidylaniline, N, N-diglycidyltoluidine, trimethylolpropane triglycidyl ether, glycerin triglycidyl ether, and various liquid polysiloxane diglycidyl ethers. In order to provide stable conductivity, it is preferable to have two or more glycidyl groups. Neopentyl glycol diglycidyl ether, glycerin diglycidyl ether, and trimethylolpropane triglycidyl ether are preferred. Particularly, neopentyl glycol diglycidyl ether is preferable.

The content of such a liquid epoxy compound is preferably 10 to 80% by weight of the whole organic binder. If the content is less than 10% by weight, the viscosity is increased, the workability is deteriorated, and the conductivity tends to be unstable.
If it exceeds 80% by weight, it becomes difficult to obtain sufficient strength. More preferably, it is 20 to 70% by weight. The phenoxy resin used in the present invention includes bisphenol A type, F type, AD type and the like, like the epoxy resin. These are similar in structure to the epoxy resin, and act as a flexible material in a composition having a high crosslinking density, and impart high toughness, so that a composition having high strength and toughness can be obtained.

The phenoxy resin is one of the organic binders.
It is preferable to add 〜20% by weight. When the content of the phenoxy resin is less than 1% by weight, it is difficult to repair. On the other hand, if it exceeds 20% by weight, it is difficult to obtain a sufficient strength, the viscosity becomes high and the workability deteriorates. In addition, the conductivity and the stability of the conductivity are adversely affected. It is more preferably 1 to 15% by weight, particularly preferably 1 to 10% by weight.

In the present invention, the term “repair” refers to heating the adhesive, using a solvent, or using a solvent in a heated state to reduce the shear strength to 3 kgf or less, and to use a slight force such as pulling with tweezers. Applying force causes the adherend to be detached from the member, removing the conductive adhesive, attaching a new conductive adhesive, and re-adhering.

In order to satisfactorily repair by heating, the heating is performed at a temperature not higher than the temperature at which the adhesive member does not deteriorate, and at 150 ° C. or more, preferably 180 ° C. or more. Various solvents can be used for repairing with a solvent. Solvents such as methyl cellosolve acetate, butyl cellosolve, ethyl cellosolve, and methyl cellosolve can be used alone or in a mixture of a plurality of solvents.

A known curing agent can be used for the conductive adhesive of the present invention, if necessary. For example, aliphatic polyamines include triethylenetetramine and m-xylenediamine, and aromatic amines include m-phenylenediamine and diaminodiphenylsulfone. Tertiary amines include benzyldimethylamine and dimethylamino. Examples include methylphenol, acid anhydrides include phthalic anhydride and hexahydrophthalic anhydride, and boron trifluoride amine complex includes BF3-piperidine complex. Alternatively, a bisphenol compound such as bisphenol A may be used. Dicyandiamide, 2-ethyl-4
-Methylimidazole, tris (methylamino) silane and the like. These may be used alone or in combination of two or more. When the reactivity of these hardeners at room temperature is high, a liquid containing the hardener is mixed with a conductive adhesive immediately before use, or microcapsules in which the hardener is encapsulated in a capsule of about 100 μm gelatin or the like. And so on.

The conductive filler used in the present invention includes a conductive metal such as silver, gold, copper and nickel, alumina, and the like.
Examples thereof include those in which the surface of an inorganic insulator such as glass or an organic polymer such as polyethylene or polystyrene is coated with a conductive substance, carbon, graphite, and the like. These may be used alone or in combination of two or more. It is also possible to use a conductive filler having a gradient composition metal structure described in JP-A-4-268381. It is also possible to use a conductive filler coated with a low-melting-point metal described in JP-A-7-179832.

With respect to the shape of these conductive fillers, spherical, scaly or dendritic ones are used alone or in a mixture of two or more. A mixture of coarse powder and fine powder can be used. In particular, it is a preferred embodiment to use a mixed system of spherical powder and flaky powder. In the mixed system, the flaky powder forms a current-carrying path, and the spherical powder can balance conductivity and strength in order to strengthen the matrix of the resin layer, so that a preferable conductive adhesive is obtained. Guessed. Further, a mixture of a high melting point metal powder and a low melting point metal powder can be used.

The compounding ratio of the conductive filler can be selected in an appropriate range according to the use of the conductive adhesive.
When used as a normal conductive adhesive without a pressurizing process, the compounding ratio is preferably from 65% by weight to 90% by weight. If it is less than 65% by weight, it is difficult to obtain sufficient conductivity. If it exceeds 90% by weight, workability is poor. More preferably, it is 70% by weight to 90% by weight.

The conductive adhesive in the present invention can be used as an anisotropic conductive paste having a pressurizing process by reducing the content of a conductive filler. In this case, the compounding ratio of the conductive filler is 0.1% by weight to 6%.
A range of 5% by weight is preferred. If the amount is less than 0.1% by weight, open is likely to occur, and it is difficult to obtain sufficient conductivity.
If the amount exceeds 65% by weight, a short circuit may occur.
More preferably, it is 2% by weight to 65% by weight.

For the conductive paste of the present invention, an appropriate solvent or diluent can be used as long as the characteristics of the present invention are not impaired. This gives the paste sufficient viscosity and thixotropy. The solvent may be a known solvent, for example, dimethylformamide, dimethylacetamide, N-methyl-pyrrolidone, methyl cellosolve, methyl carbitol, carbitol, carbitol acetate, butyl cellosolve acetate, ethyl cellosolve acetate,
Solvents such as methyl cellosolve acetate, butyl cellosolve, ethyl cellosolve, and methyl cellosolve. These solvents may be used alone or in a mixture of a plurality of solvents in appropriate amounts. It is preferable from the viewpoint of workability that the viscosity of the obtained solution or paste is from 2000 to 400,000 cP, more preferably from 10,000 to 100,000 cP.

An antioxidant can be added to the conductive adhesive of the present invention, if necessary. Examples of the antioxidant include fatty acids and metal salts thereof, dicarboxylic acids, oxycarboxylic acids, phenols, metal chelating agents, higher aliphatic amines, organic titanate compounds, rosin, anthracene and derivatives thereof. Commercially available solder flux can also be used. Among them, fatty acids such as propionic acid, linoleic acid, stearic acid, lauric acid and pentadecylic acid and polyhydric phenol monomers such as resorcin, catechol and hydroquinone are particularly preferred. In general, the amount of the antioxidant to be added is preferably 0.1 to 20% by weight based on the amount of the conductive filler. However, if the amount is too small, the conductive filler is easily oxidized. The content is particularly preferably from 0.3 to 10% by weight because the properties and conductivity are lowered and the hygroscopicity of the paste is increased.

The conductive adhesive used in the present invention includes a curing accelerator, a flame retardant, a leveling agent, a thixotropic agent, an anti-settling agent, a coupling agent, a pigment, an antifoaming agent, a corrosion inhibitor, and a tackifier. Various physical properties can be improved by adding various additives. The conductive adhesive of the present invention can be obtained by kneading the above-mentioned various components using various kneading machines such as a ball mill, a roll mill, and a planetary mixer in a conventional manner, for example, for 10 to 60 minutes.

The kneaded conductive adhesive is applied to an insulating substrate or a lead frame by a method such as screen printing or dispenser application. The heating and curing conditions of the conductive adhesive of the present invention are not particularly limited as long as the resin is sufficiently cured and deterioration by heat is not a problem. As a general temperature range, 150 ° C. to 240 ° C.,
Preheating may be performed at a lower temperature for the purpose of melting the solid curing agent or preventing the formation of voids.

[0028]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described with reference to the following Examples and Comparative Examples. The evaluation was performed by the following method.・ Shear strength is determined by applying a conductive adhesive on a copper plate to a thickness of 70 to 10
Keep it at 0 µm, apply 2 mm wide and 2 mm long, apply 5 copper chips (2 mm x 2 mm x 1 mm) and cure at a predetermined temperature. Push the tip of the push-pull gauge into the prepared cured product to remove the chip. It was measured by reading the intensity. -The repairability of the cured product is determined by heating the cured product prepared above in an oven at 180 ° C for 10 minutes (heating repair) or heating the cured product to 100 ° C on a hot plate and applying N to the adhesive surface.
-Methyl-pyrrolidone (NMP) was added dropwise (solvent repair), and the copper chip was pulled with tweezers to evaluate whether the copper chip was easily dropped.・ Volume resistivity is measured by applying a conductive adhesive to FR4 substrate with a film thickness of 50 to 100 μm, applying a 1 cm width and 7 cm length, and curing it at a predetermined temperature. It was measured by using a multimeter and calculated by substituting numerical values into the following equation.

Volume resistivity = R × t × 10 ^-4 Ωcm
R: Resistance value t: Film pressure μm ・ Stability of volume resistivity is measured by a heat cycle tester (-2
(5 to 125 ° C., 30 minutes each), the sample for measuring the volume resistivity was placed, and the volume resistivity after 500 cycles was measured and evaluated. It should be noted that% in Examples and Comparative Examples
And parts mean parts by weight and parts by weight.

[0030]

Example 1 Phenoxy resin (PPHEN Co., Ltd. P
17.5 parts of a 10% solution of neopentyl glycol diglycidyl ether of KHC), 14.8 parts of a novolak type phenol resin (BRG555 manufactured by Showa Kogaku Co., Ltd.), 1500 NP manufactured by Kyoeisha Chemical Co., Ltd. ) 25.1 parts, and average particle size 3
μm spherical silver powder (DSP1100 manufactured by Daido Steel Co., Ltd.)
Novacure HX3, a microcapsule-type epoxy curing agent, was added to a paste obtained by kneading 614 parts with three rolls.
741 (manufactured by Asahi Kasei Corporation) was added and kneaded with a metal spatula for 5 minutes.

This conductive adhesive was cured at 180 ° C. for 1 hour and evaluated by the above method. The shear strength was 16 kgf and the volume resistivity was 2.0 × 10 ⁻⁴ Ωcm. Further, the volume resistivity after the heat cycle test is 2.2 × 10 ⁻⁴ Ω.
cm (+ 10%). When a repairability test was performed, both heating repair and solvent repair were possible. The measured shear strength at that time was about 2 kgf. further,
After removing the conductive adhesive, a new conductive adhesive was applied and re-adhered, and the same performance as the first one was obtained.

[0032]

Example 2 Phenoxy resin (P.P.
17.5 parts of a 10% solution of KHC) in neopentyl glycol diglycidyl ether, 12.4 parts of a novolak-type phenol resin (BRG555 manufactured by Showa Polymer Co., Ltd.), and a bisphenol A-type epoxy resin (AER2 manufactured by Asahi Ciba Co., Ltd.)
50) 2.4 parts, neopentyl glycol diglycidyl ether (1500 NP, manufactured by Kyoeisha Chemical Co., Ltd.) 25.1
And a paste obtained by kneading 614 parts of spherical silver powder (manufactured by Daido Steel Co., Ltd.) having an average particle size of 3 μm with a three-roll mill, and adding NOVACURE HX3741 as a microcapsule-type epoxy curing agent (Asahi Chemical Industry Co., Ltd.) Was added and kneaded with a metal spatula for 5 minutes.

This conductive adhesive was cured at 180 ° C. for 1 hour and evaluated by the above method. The shear strength was 18 kgf and the volume resistivity was 3.0 × 10 ⁻⁴ Ωcm. Further, the volume resistivity after the heat cycle test is 3.4 × 10 ⁻⁴ Ω.
cm (+ 13%). When the repairability was evaluated, both the heating repair and the solvent repair were possible.

[0034]

Example 3 2.8 parts of novolak type phenol resin,
A conductive adhesive was prepared and evaluated in the same manner as in Example 2 except that 12.0 parts by weight of bisphenol A type epoxy resin was added. The shear strength was 20 kgf and the volume resistivity was 3.8 × 10 ⁻⁴ Ωcm. Further, the volume resistivity after the heat cycle test was 4.4 × 10 ⁻⁴ Ωcm (+ 16%). When the repairability was evaluated, both heating repair and solvent repair were possible.

[0035]

Example 4 Spherical silver powder having an average particle diameter of 3 μm (DSP1100 manufactured by Daido Steel Co., Ltd.) 600 as a conductive filler
A conductive adhesive was prepared and evaluated in the same manner as in Example 1 except that a mixture of the above-mentioned parts and 14 parts of flaky silver powder (manufactured by Daido Steel Co., Ltd.) having an average major axis of 10 μm was used. Shear strength is 14 kgf, volume resistivity is 1.0 × 1
It was 0 ^-4 Ωcm. Further, the volume resistivity after the heat cycle test was 1.1 × 10 ⁻⁴ Ωcm (+10
%). When the repairability was evaluated, both heating repair and solvent repair were possible.

[0036]

Example 5 A conductive adhesive was prepared and evaluated in the same manner as in Example 1 except that glycerin diglycidyl ether was used instead of neopentyl glycol diglycidyl ether. Both heating repair and solvent repair are possible, shear strength is 18kgf, volume resistivity is 2.4 × 1
It was 0 ^-4 Ωcm. Further, the volume resistivity after the heat cycle test was 2.6 × 10 ⁻⁴ Ωcm (+10
%)

[0037]

Example 6 A conductive adhesive was prepared and evaluated in the same manner as in Example 1 except that trimethylolpropane triglycidyl ether was used instead of neopentyl glycol diglycidyl ether. 17k shear strength
gf and volume resistivity were 1.5 × 10 ⁻⁴ Ωcm.
Furthermore, the volume resistivity after the heat cycle test is 1.6 ×
10 ⁻⁴ Ωcm (+ 7%). When the repairability was evaluated, both heating repair and solvent repair were possible.

[0038]

Example 7 Phenoxy resin (PAPEN Co., Ltd. P
26 parts of a 10% solution of KHC) in neopentyl glycol diglycidyl ether and 1 part of neopentyl glycol
A conductive adhesive was prepared and evaluated in the same manner as in Example 1 except that the amount was 7.4 parts. Shear strength is 15kgf,
The volume resistivity was 3.2 × 10 ⁻⁴ Ωcm. Further, the volume resistivity after the heat cycle test is 3.6 × 10 ^−4.
Ωcm (+ 13%). When the repairability was evaluated, both heating repair and solvent repair were possible.

[0039]

Example 8: Phenoxy resin (P.P.
A conductive adhesive was prepared and evaluated in the same manner as in Example 1 except that 42 parts of a 10% solution of neopentyl glycol diglycidyl ether (KHC) and 3.0 parts of neopentyl glycol diglycidyl ether were used. . Shear strength is 14 kgf, volume resistivity is 4.0 × 10 ^-4 Ωcm
Met. Further, the volume resistivity after the heat cycle test was 4.6 × 10 ⁻⁴ Ωcm (+ 15%). When the repairability was evaluated, both heating repair and solvent repair were possible.

[0040]

Embodiment 9 Phenoxy resin (PPHEN manufactured by PAPHEN Co., Ltd.)
17.5 parts of a 10% solution of neopentyl glycol diglycidyl ether of KHC), 14.8 parts of a novolak type phenol resin (BRG555 manufactured by Showa Kogaku Co., Ltd.), 1500 NP manufactured by Kyoeisha Chemical Co., Ltd. ) 25.1 parts, hydroquinone 1
2.7 parts, 1.5 parts of stearic acid and 614 parts of dendritic copper powder (FCC-115 manufactured by Fukuda Metal Foil & Powder Co., Ltd.)
17.2 parts of NOVACURE HX3741 (manufactured by Asahi Kasei Kogyo Co., Ltd.), which is a microcapsule-type epoxy curing agent, was added to the paste obtained by kneading with this roll, and kneaded with a metal spatula for 5 minutes.

This conductive adhesive was cured at 180 ° C. for 1 hour and evaluated by the above method. The shear strength was 11 kgf and the volume resistivity was 7.2 × 10 ⁻⁴ Ωcm. Further, the volume resistivity after the heat cycle test is 8.4 × 10 ⁻⁴ Ω.
cm (+ 17%). When the repairability was evaluated, both heating repair and solvent repair were possible.

[0042]

Example 10 17.5 parts of a 10% solution of a phenoxy resin (PKHC's PKHC) in neopentyl glycol diglycidyl ether, 12.4 parts of a novolak-type phenol resin (BRG555 manufactured by Showa Polymer Co., Ltd.), bisphenol A type epoxy resin (AER manufactured by Asahi Ciba Co., Ltd.)
250) 2.4 parts, neopentyl glycol diglycidyl ether (1500 NP, manufactured by Kyoeisha Chemical Co., Ltd.)
1 part, hydroquinone 12.7 parts, stearic acid 1.5 parts and dendritic copper powder (FCC-1 manufactured by Fukuda Metal Foil Industry Co., Ltd.)
15) To a paste obtained by kneading 614 parts with three rolls, 17.2 parts of NOVACURE HX3741 (manufactured by Asahi Kasei Kogyo Co., Ltd.), which is a microcapsule type epoxy curing agent, was added, and kneaded with a metal spatula for 5 minutes.

This conductive adhesive was cured at 180 ° C. for 1 hour and evaluated by the above method. The shear strength was 13 kgf and the volume resistivity was 7.8 × 10 ⁻⁴ Ωcm. Further, the volume resistivity after the heat cycle test is 9.2 × 10 ⁻⁴ Ω.
cm (+ 18%). When the repairability was evaluated, both heating repair and solvent repair were possible.

[0044]

Example 11 (1) Preparation of Copper Alloy Powder Copper alloy powder was obtained by the following method. Copper powder (purity 99.9
%) 863 g and silver powder (purity 99.9%) 63 g were mixed, placed in a graphite crucible (with a boron nitride nozzle), and melted by high-frequency induction heating under an argon atmosphere to obtain 160 g.
Heated to 0 ° C. This melt was ejected from the nozzle under argon atmospheric pressure for 30 seconds. At the same time, 4.2 NTPm ³ of argon gas with a cylinder (cylinder pressure of 150 atm) was jetted from the surrounding nozzle toward the jetting melt. The obtained powder was scanned with a scanning electron microscope (S manufactured by Hitachi, Ltd.)
-900), the spherical shape (average particle size 19.6μ)
m). The silver concentration on the surface of this powder was determined by XPS (KRA
As a result of analysis using XSAM800 manufactured by Tos Corporation, A
g / (Ag + Cu) (atomic ratio) was 0.147.
When the particles were dissolved in concentrated nitric acid and the average silver concentration was measured by ICP (JY38P2 manufactured by Seiko Instruments Inc.), Ag / (Ag + Cu) (atomic ratio) was 0.042.
Met. The silver concentration on the powder surface was 3.5 times the average silver concentration.
It was twice. Of the obtained copper alloy powder, a powder having a diameter of 20 μm or less was classified and used for making a paste. (2) Preparation and evaluation of conductive adhesive A conductive adhesive was prepared in the same manner as in Example 9 except that the copper filler was changed to the copper alloy prepared in (1) above, and evaluated by the same method. Shear strength 16 kgf, the volume specific resistance was 5.0 × 10 ^-4 4Ωcm. Furthermore the volume resistivity after the heat cycle test 5.4 × 10 ^-4 4Ωcm
(+ 8%). When the repairability was evaluated, both heating repair and solvent repair were possible.

[0045]

Example 12 A conductive adhesive was prepared in the same manner as in Example 10 except that the copper filler was changed to the copper alloy prepared in (1) of Example 11, and evaluated by the same method. The shear strength was 18 kgf and the volume resistivity was 5.5 × 10 ⁻⁴ Ωcm. Further, the volume resistivity after the heat cycle test was 6.0 × 10 ⁻⁴ Ωcm (+ 10%). When the repairability was evaluated, both heating repair and solvent repair were possible.

[0046]

Example 13 19.9 parts of a 10% solution of a phenoxy resin (PKHC's PKHC) in neopentyl glycol diglycidyl ether and a hydroquinone-type novolak phenol resin (Asahi Organic Materials Co., Ltd. AC20) 31.0 parts
Parts, 32.2 parts of neopentyl glycol diglycidyl ether (1500 NP manufactured by Kyoeisha Chemical Co., Ltd.), and 614 parts of the copper alloy powder prepared in Example 11 (1) were kneaded with a three-roll mill to obtain a paste. 13.2 parts of NOVACURE HX3741 (manufactured by Asahi Kasei Kogyo Co., Ltd.), which is a microcapsule type epoxy curing agent, was added and kneaded with a metal spatula for 5 minutes.

The conductive adhesive was cured at 180 ° C. for 1 hour and evaluated by the above method. The shear strength was 10 kgf and the volume resistivity was 1.0 × 10 ⁻⁴ Ωcm. Further, the volume resistivity after the heat cycle test is 1.1 × 10 ⁻⁴ Ω.
cm (+ 10%). When the repairability was evaluated, both heating repair and solvent repair were possible.

[0048]

Example 14 (1) Preparation of Solder-Plated Copper Powder 100 g of atomized copper powder (SRC-CU-20 manufactured by Fukuda Metal Foil Industry Co., Ltd.) having an average particle diameter of 10 μm was mixed in a mixed solution of 50 ml of methanol and 400 ml of water. The mixture was dispersed by stirring at 25 ° C. for 10 minutes. 5 ml of sulfuric acid was dropped into the dispersion and stirred for 5 minutes. After filtration and washing with water, the mixture was filtered again. Solder plating bath (Substar SNL41-M 250 ml, Substar SN41P 80 g (both Okuno Pharmaceutical Co., Ltd.)
And water (700 ml) were stirred at 35 ° C. for 10 minutes to perform electroless plating. After filtration and washing with water, the mixture was filtered again. After washing with methanol, it was dried at 100 ° C. for 120 minutes. 99 g of solder-plated copper powder was obtained. (2) Preparation and evaluation of conductive adhesive The solder-plated copper powder obtained in (1) was used instead of copper powder.
Instead of using hydroquinone and stearic acid, flux (Nippon Alpha Metal Co., Ltd. RM615) 14.2
A conductive adhesive was prepared in the same manner as in Example 9 except that the parts were used, cured at 180 ° C. for 30 minutes and at 200 ° C. for 15 minutes, and evaluated in the same manner. Shear strength is 10kgf,
The volume resistivity was 1.0 × 10 ⁻³ Ωcm. Further, the volume resistivity after the heat cycle test is 1.1 × 10 ^−3.
Ωcm (+ 10%). When the repairability was evaluated, both heating repair and solvent repair were possible.

[0049]

Example 15 (1) Preparation of tin-plated copper Substar SN-5A 60 ml, S as a tin plating bath
Tin-plated copper powder 9 in the same manner as in Example 13 (1) except that a mixed solution of 500 ml of N-5B and 120 g of SN-5P (both manufactured by Okuno Pharmaceutical Co., Ltd.) and 400 ml of water was used.
6 g were obtained. (2) Preparation and evaluation of conductive adhesive The tin-plated copper powder obtained in (1) was used in place of resinous copper powder, and flux (Nippon Alpha Metal Co., Ltd. RM615) 14.2 instead of hydroquinone and stearic acid. A conductive adhesive was prepared in the same manner as in Example 9 except that a part was used, cured at 180 ° C. × 30 minutes and 240 ° C. × 10 minutes, and evaluated in the same manner. The shear strength was 10 kgf and the volume resistivity was 9.0 × 10 ⁻⁴ Ωcm. Further, the volume resistivity after the heat cycle test is 1.0 × 10 ⁻³ Ω.
cm (+ 10%). When the repairability was evaluated, both heating repair and solvent repair were possible.

[0050]

Example 16 17.5 parts of a 10% solution of a phenoxy resin (PKHC's PKHC) in neopentyl glycol diglycidyl ether, 12.4 parts of a novolak type phenol resin (BRG555 manufactured by Showa Polymer Co., Ltd.), bisphenol A type epoxy resin (AER manufactured by Asahi Ciba Co., Ltd.)
250) 2.4 parts, neopentyl glycol diglycidyl ether (1500 NP, manufactured by Kyoeisha Chemical Co., Ltd.)
1 part and a paste obtained by kneading 7.4 parts of the same copper alloy powder as in Example 11 (1) with three rolls were added to Novacur HX3741 which is a microcapsule type epoxy curing agent.
17.2 parts (manufactured by Asahi Chemical Industry Co., Ltd.) was added, and the mixture was kneaded with a metal spatula for 5 minutes.

The adhesive was printed on the connecting substrate conductor by screen printing at a thickness of about 20 μm with a width of 2 mm. Curing is 1
At 80 ° C. × 20 seconds, the connection between the chip and the connection substrate was performed under a pressure of 40 g / bump. The connection substrate is glass on which an ITO electrode is formed on the entire surface, and the connected chip is a gold bump (70 μ
(m pitch) LSI chip. JIS-
When evaluated by a 90 ° peel test according to Z0237, it was as good as 1 g / cm. The connection resistance value was measured by the four-terminal method, and was obtained as a value obtained by theoretically subtracting the resistance value of the circuit up to the connection portion. The connection resistance value was as good as 40 mΩ, and the change in conductivity during the heat cycle was 42 mΩ (5%). Met.

The insulation was determined to be 1 × 10 ¹² Ω or more, as determined by the insulation resistance when a voltage of 100 V was applied between the adjacent electrodes. When the testability of the test piece, which was once bonded by thermocompression bonding, was evaluated by whether it could be peeled off by heating to 180 ° C., the test piece was repaired well.

[0053]

Comparative Example 1 14.8 parts of a novolak type phenol resin (BRG555 manufactured by Showa Polymer Co., Ltd.) and neopentyl glycol diglycidyl ether (15 manufactured by Kyoeisha Chemical Co., Ltd.)
Novacure HX3741 (a microcapsule-type epoxy curing agent) was added to a paste obtained by kneading 42.1 parts of 00NP) and 614 parts of spherical silver powder (DSP1100 manufactured by Daido Steel Co., Ltd.) having an average particle size of 3 μm with three rolls. 17.2 parts of Asahi Kasei Kogyo Co., Ltd.) was added and kneaded with a metal spatula for 5 minutes. This conductive adhesive was cured at 180 ° C. for 1 hour and evaluated by the above method. The shear strength was 18 kgf. When the repairability was evaluated, neither heating repair nor solvent repair could be performed.

[0054]

[Comparative Example 2] Phenoxy resin (PAPHEN's P
KHC) Neopentyl glycol diglycidyl ether
17.5 parts of 10% solution and bisphenol A type epoxy
14.8 parts of resin (AER250 manufactured by Asahi Ciba Co., Ltd.), Neo
Pentyl glycol diglycidyl ether (Kyoeisha Chemical
25.1 parts and 1500 NP manufactured by Co., Ltd.
μm spherical silver powder (DSP1100 manufactured by Daido Steel Co., Ltd.)
614 parts of a paste obtained by kneading with a three-roll mill,
Novacure HX3, a black capsule type epoxy curing agent
741 (manufactured by Asahi Chemical Industry Co., Ltd.)
The mixture was kneaded with a spatula for 5 minutes. 180 ° C x
It was cured for 1 hour and evaluated by the above method. The volume resistivity is
5 × 10^-3Ωcm, by heat cycle test
2 × 10 ^-3Ωcm.

[0055]

Comparative Example 3 A conductive adhesive was prepared and evaluated in the same manner as in Example 1 except that polyvinyl alcohol (BM-2 manufactured by Sekisui Chemical Co., Ltd.) was used instead of the phenoxy resin. The shear strength was 5 kgf and the volume resistivity was 2 × 10 ⁻³ Ωcm. When the repairability was evaluated, neither heating repair nor solvent repair could be performed.

[0056]

[Comparative Example 4] Phenoxy resin (P.P.
17.5 parts of a 10% NMP solution of KHC) and a novolak type phenol resin (BRG555, manufactured by Showa Polymer Co., Ltd.)
4.8 parts, 25.1 parts of NMP and 614 parts of spherical silver powder (DSP1100 manufactured by Daido Steel Co., Ltd.) having an average particle size of 3 μm
17.2 parts of NOVACURE HX3741 (manufactured by Asahi Kasei Kogyo Co., Ltd.), which is a microcapsule-type epoxy curing agent, was added to the paste obtained by kneading with this roll, and kneaded with a metal spatula for 5 minutes. This conductive adhesive was cured at 180 ° C. for 1 hour and evaluated by the above method. The shear strength was 6 kgf and the volume resistivity was 9.0 × 10 ⁻⁴ Ωcm. Furthermore, the volume resistivity after the heat cycle test is 1.2 × 10 ⁻³ Ωcm.
(+ 33%).

[0057]

Industrial Applicability The conductive adhesive of the present invention is repairable, has sufficient adhesive strength and conductivity enough for practical use, and is stable in conductivity for a long period of time. Useful.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI C08L 63/00 C08L 63/00 A B

Claims (5)

[Claims] 1. A conductive adhesive comprising a thermosetting resin, a phenoxy resin, a liquid epoxy compound having at least one glycidyl group in one molecule, and a conductive filler, wherein the thermosetting resin is phenol. A conductive adhesive characterized by being a resin or a mixture of a phenol resin and an epoxy resin. 2. The conductive adhesive according to claim 1, wherein the content of the phenoxy resin is 1 to 20% by weight of the whole organic binder. 3. The liquid epoxy compound has a viscosity of 200 cP.
The conductive adhesive according to claim 1, wherein: 4. The conductive adhesive according to claim 1, wherein the phenol resin is a novolak type phenol resin. 5. The conductive adhesive according to claim 1, wherein the epoxy resin is a bisphenol A type epoxy resin.