JPH10298518A - Insulating adhesive composition and heat seal connector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an insulating adhesive composition excellent in initial adhesion and retention of the adhesion, and further to obtain a heat seal connector capable of precisely keeping the electric connection in high reliability even at a high temperature and even after subjecting the connector to a heat shock. SOLUTION: This heat seal connector has an anisotropic and conductive adhesive layer 16 formed out of an insulating adhesive 15 including conductive particles 14 formulated therewith at the connecting part of a conductive line 13 on the surface of a flexible substrate 12. The insulating adhesive 15 is constituted of a composition comprising 100 pts.wt. elastomer component such as NBR, SBS, SEBS and SIS 20-150 pts.wt. solid or semisolid bisphenol A type epoxy resin having 200-5,000 epoxy equivalent, 20-200 pts.wt. component containing phenolic hydroxyl group having 300-7,000 molecular weight such as t-butylphenol, 0.1-10 pts.wt. cross-linking agent of the elastomer component, and 1-50 pts.wt. metal oxide such as zinc oxide.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an insulating adhesive composition and a heat seal connector, and more particularly, to a liquid crystal display (LCD) or a plasma display panel (PDP) and a circuit board on which a driving circuit is mounted. The present invention relates to a heat seal connector used for electrical connection between the members and the like, and an insulating adhesive composition suitable for this type of heat seal connector.

[0002]

2. Description of the Related Art Conventionally, a heat seal connector has been known as an L connector.
Display body such as CD or DPD and printed circuit board (PC
B), connection with a flexible printed circuit (FPC),
Alternatively, it is used for connection between a PCB and an FCP, and the one shown in FIGS. 1 and 2 and the one shown in FIG. 3 are known (see Japanese Patent Application Laid-Open No. 8-335472). As shown in FIG. 1, the former heat seal connector is formed by screen-printing a desired conductive line 13 on one surface of a flexible base material 12 using a conductive paste or the like, and connecting an end of the conductive line 13. An anisotropic conductive adhesive layer 16 formed by dispersing conductive particles 14 in a heat-bonding insulating adhesive 15 is provided on the portion, and an insulating resist layer is provided on other portions not involved in the connection of the conductive line 13. 17 is provided.

[0003] Such a heat seal connector is shown in FIG.
As shown in FIG. 2, the conductive line 13 is connected to another ITO (individual).
In the case of connecting to the transparent electrode 21 of the um tin oxide) substrate, the anisotropic conductive adhesive layer 16 is brought into contact with the transparent electrode 21, and in this state, the adhesive layer 16 is thermally fused and bonded by heating. The conductive particles 14 are composed of the conductive line 13 and the transparent electrode 21
To electrically connect the conductive line 13 and the transparent electrode 21 to each other.

In the latter heat seal connector, as shown in FIG. 3, a conductive line 13 is formed of a conductive paste in which conductive particles 14 are dispersed and compounded, and an insulating adhesive for covering a connecting portion of the conductive line 13 is used. It is constituted by providing a layer 15 '. Also in this heat seal connector, the insulating adhesive layer 15 ′ is bonded by heat fusion, and the conductive particles 14 protruding from the conductive line 13 are brought into contact with the transparent electrode 21 to obtain electrical conduction.

[0005] By the way, this heat seal connector,
Since an insulating adhesive (layer) is usually provided on a conductive line by a method such as printing or coating, it is desired that the insulating adhesive (layer) be easily dissolved in a general-purpose solvent. Therefore, the insulating adhesive has, as a main component, a thermoplastic resin such as styrene-based elastomer, thermoplastic polyester, thermoplastic polyurethane, chloroprene, and acrylonitrile butadiene rubber in terms of adhesive strength, adhesive strength, and ease of processing. Things are heavily used.

[0006]

However, since the above-mentioned heat seal connector uses a thermoplastic resin for the insulating adhesive, it has poor heat resistance and poor electrical connection reliability at high temperatures. Was. That is, in such a heat seal connector, since the reliability of the electrical connection greatly depends on the characteristics of the insulating adhesive, the electrical connection becomes unstable when the adhesive strength of the adhesive decreases. In particular, in recent years, the use of heat seal connectors has also expanded, and they have been used in thermally harsh environments, for example, in high-temperature environments such as the interior of automobiles in the summer season. The connection terminal pitch required for the seal connector is 0.2
Since the fineness is reduced to about the mm pitch, the particle size of the conductive particles tends to be small, and the thickness of the adhesive applied tends to be small, the above-mentioned problem has been remarkable.

On the other hand, many attempts have been made to use a thermosetting resin instead of a thermoplastic resin for the insulating adhesive as a measure against the above-mentioned problem. However, the thermosetting resin is flexible due to its molecular structure. Poor properties, its shear adhesive strength is strong, but peel adhesive strength is weak, and curing progresses from being applied as an adhesive to thermocompression bonding, time limit until thermocompression bonding becomes impossible, So-called pot life is short, storage at low temperature is indispensable, and furthermore, it has the drawback that the adhesive interface is easily peeled off by the impact of a thermal cycle. The present invention has been made in view of the above problems, a composition of an insulating adhesive excellent in initial adhesive strength, adhesive holding power,
It is another object of the present invention to provide a heat seal connector that can maintain electrical connection reliably and highly reliably even at high temperatures and thermal shock.

[0008]

In order to achieve the above object, the insulating adhesive composition according to the first aspect of the present invention comprises one or more types of elastomers selected from diene rubbers and styrene elastomers. 100 parts by weight of a component, 20 to 150 parts by weight of a solid or semi-solid epoxy resin having an epoxy equivalent of 200 to 5000, and a molecular weight of 300
20 to 200 parts by weight of one or more kinds of phenolic hydroxyl group-containing components which are 7000 to 7000, 0.1 to 10 parts by weight of a crosslinking agent for crosslinking the elastomer component, and 1 to 50 parts by weight of metal oxide. It is comprised including.

According to a second aspect of the present invention, a flexible substrate has a conductive line on at least one surface thereof, and an insulating adhesive and conductive particles are included in at least a portion of the conductive line involved in connection. In a heat seal connector provided with one side conductive means, the composition constituting the insulating adhesive is selected from diene rubber or styrene elastomer.
100 parts by weight of one or more kinds of elastomer components and epoxy resin 20 to 15 having an epoxy equivalent of 200 to 5000
0 parts by weight, one or more phenolic hydroxyl group-containing components having a molecular weight of 300 to 7000, 20 to 200 parts by weight, and a crosslinking agent 0.1 to crosslinking the elastomer component.
10 parts by weight and 1 to 50 parts by weight of a metal oxide.

The insulating adhesive composition and the heat seal connector according to the present invention are characterized in that the phenolic hydroxyl group-containing component comprises t-butylphenol, poly-
An embodiment (claim 3) using at least one selected from p-vinylphenol and terpene phenol can be provided.

That is, the present inventor has conducted various studies on methods for solving the above-mentioned problems. As a result, this insulating adhesive has an elastomer component, an epoxy resin, and a phenolic hydroxyl group acting as a curing agent for the epoxy resin. By blending a cross-linking agent, a cross-linking aid and a metal oxide as a heat-resistant filler in order to cross-link the elastomer component, the insulating adhesive component gradually increases in a high-temperature environment for a long time. And gained the knowledge of increasing the adhesive force by gradually curing,
Based on this finding, the research on the reliability of the electrical connection was advanced, and the present invention was completed.

As the elastomer component, NBR (acrylonitrile butadiene copolymer rubber), SBS (styrene-butadiene-styrene block copolymer), SEBS
(Hydrogenated SBS) and SIS (styrene-isoprene-styrene block copolymer), which include an organic anhydride group such as a dicarboxylic anhydride group or a carboxylic acid group in the molecular structure thereof. And a commercially available product may be used, and one or more types may be used. As the elastomer component, NBR is preferable from the viewpoint of heat resistance, and particularly, NBR containing a carboxylic acid group capable of reacting with an epoxy resin is preferable because it has a large effect of improving flexibility.

As the epoxy resin, a commercially available epoxy resin can be appropriately used, and its epoxy equivalent is 200 to 5000.
Semi-solid or solid, especially ITO or FPC
A bisphenol A type epoxy resin having excellent adhesion to the surface is preferred. When this epoxy resin is liquid,
When used as an insulating adhesive, epoxy molecules move easily,
A semi-solid or solid material is selected because the potable life (pot life) from application of the insulating adhesive to the heat seal connector to pressure bonding is reduced.
When the epoxy equivalent is less than 200, the epoxy resin tends to be in a liquid state. When the epoxy equivalent is more than 5,000, the melting temperature becomes too high than the crimping temperature of the heat seal connector, so that the adhesiveness cannot be obtained. The range is 200-5000, preferably 200-30.
00 is set.

The phenolic hydroxyl group-containing component functions as an epoxy resin curing agent and / or tackifier. The phenolic hydroxyl group-containing component includes t-butylphenol and terpenephenol which are excellent in tackiness, and poly-p-vinylphenol which is an excellent curing agent.
enol) and the like, and commercially available ones can be used. However, from the viewpoint of heat resistance, t-butylphenol and poly-p-vinylphenol are preferable. In particular, poly-p which has a simple molecular structure and is easy to mix and design can be used. -Vinyl phenol is more preferred. This phenolic hydroxyl group-containing component has a molecular weight of 30.
If it is less than 0, the resin has a low softening point and low heat resistance, and if it is more than 7000, its melting temperature becomes too high than the crimping temperature of the heat seal connector, and it becomes impossible to obtain adhesiveness. ~ 7000.

The amount of the epoxy resin is preferably 20 to 150 parts by weight based on 100 parts by weight of the elastomer component. If the amount is less than 20 parts by weight, not only the adhesive strength as an insulating adhesive is reduced but also the heat resistance is reduced. The properties are not satisfactory, and if the amount is more than 150 parts by weight, flexibility is lost and peel strength is reduced. Further, the compounding amount of the phenolic hydroxyl group-containing component is preferably 20 to 200 parts by weight with respect to 100 parts by weight of the elastomer component. When the amount is less than 20 parts by weight, the initial adhesive strength is small. This may lead to a decrease in flexibility and a deterioration in moisture resistance.

Further, as a crosslinking agent, sulfur, ethylene thiourea, diethyl thiourea, N-cyclohexyl-2
-Benzothiazole (N-cyclohexyl-2-benzothiazol
e), tetramethylthiuram disulfide (tetramethyl
thiuram disulfide), 2-benzothiazolyl disulfide (2-benzothiazolyl disulfide), etc., but those other than sulfur are preferable in consideration of scorch property and bleeding to the surface. The amount of the crosslinking agent is preferably 0.1 to 10 parts by weight with respect to 100 parts by weight of the elastomer component. If the amount is less than 0.1 part by weight, the crosslinking may not proceed sufficiently. If the amount is larger than the weight part, scorch tends to occur, which is not desirable.

The metal oxide serves as a crosslinking aid between the elastomer component and the crosslinking agent, and improves the heat resistance of the insulating adhesive, which is an organic compound as an inorganic compound. This is selected from one or more metal oxides selected from zinc oxide (ZnO), magnesium oxide (MgO), calcium peroxide (CaO ₂ ), titanium dioxide (TiO ₂ ), etc. 1 to 50 parts by weight is desirable. If the amount of the metal oxide is less than 1 part by weight, the above-mentioned effects are not sufficiently exhibited. If the amount is more than 50 parts by weight, the adhesive strength and the base material strength of the insulating adhesive are reduced. In particular, this metal oxide is preferred because magnesium oxide has an effect of improving heat resistance when t-butylphenol is used as the phenolic hydroxyl group-containing component, and zinc oxide is also a crosslinking aid for the elastomer component. In addition, titanium dioxide having an ultraviolet absorbing effect is preferably used for those used in an environment where light resistance is desired.

To the insulating adhesive composition of the present invention, in addition to the above-mentioned materials, a tackifier, various coupling agents, an antioxidant, a coloring agent, an ultraviolet absorber and the like can be appropriately added. In particular, when used as an anisotropic conductive means in a heat seal connector (corresponding to FIGS. 1 and 2 described above), conductive particles are dispersed. As the conductive particles, for example, gold,
Examples thereof include metal particles such as silver, copper, nickel, palladium, stainless steel, brass, and solder, ceramic particles such as tungsten carbide and silica carbide, carbon particles, and plastic particles having a metal-coated surface. If the amount of the conductive particles is too small, poor conduction tends to occur,
If the amount is too large, insulation failure is likely to occur. Therefore, the amount is preferably 0.01 to 50 parts by volume, preferably 1 to 10 parts by volume with respect to 100 parts by volume of the insulating adhesive composition.

The insulating adhesive composition may be used for a heat seal connector having conductive lines containing conductive particles as shown in FIG. 3 to constitute anisotropic conductive means.
In this embodiment, the conductive particles may be the same as those used for the anisotropic conductive adhesive described above. However, if the amount is too small, poor conduction is likely to occur. Since it becomes difficult, the conductive line 10
0.01 to 50 parts by weight, preferably 0 parts by volume,
The amount may be 1 to 10 parts by weight.

When the insulating adhesive composition is used, it is dissolved in a solvent to form a solution, which is applied to a desired position of the heat seal connector by an appropriate coating method or printing method, and is adhered. Form an agent layer. This solvent is usually an ester, ketone, ether ester, ether, alcohol, or hydrocarbon solvent such as methyl acetate, methyl ethyl ketone, butyl cellosolve acetate, ethyl carbitol acetate, diisoamyl ether, and cyclohexanol. , Petroleum spirit, toluene and the like are used.

The heat seal connector using the insulating adhesive composition thus produced is described in FIG.
2, or as shown in FIG. And
Referring to FIG. 1, a sheet made of a known material such as polyester or polyimide is used for the flexible base material 12, and the sheet having a thickness of 10 to 100 μm is selected. The conductive lines 13 are formed by screen printing or the like of a conductive paste obtained by mixing an organic binder with a conductive agent such as silver powder having a particle size of about 0.01 to 10 μm, copper powder, carbon black, and graphite. This may also be a known one. Conductive line 13
Is usually formed only on one side of the flexible base material 12, but it is also possible to form the conductive base material on both sides of the flexible base material 12 by conducting through through holes, for example.

As the insulating resist 17, a hardening agent, a vulcanizing agent, various deterioration preventing agents and the like are used as needed based on a synthetic resin such as polyamide or polyester, various synthetic rubbers, or a mixture thereof. Dissolved in the solvent as described above with the addition of additives, and those formed by screen printing, etc., polyester, vinyl chloride and other films coated with an adhesive such as acrylic resin and stuck However, it is selected in consideration of required insulating properties, surface protection properties, costs, and the like.

[0023]

In the insulating adhesive composition according to the present invention, the elastomer component improves the flexibility of the epoxy resin to improve the peel strength and the thermal shock resistance, and the elastomer component is also cross-linked by a cross-linking agent and a metal oxide. To form an elastomer having excellent heat resistance. In addition, the epoxy resin reacts with the phenolic hydroxyl group-containing component and cures, but the epoxy resin is solid or semi-solid and has low reactivity, so that not only long pot life can be obtained but also excellent high-temperature durability can be obtained. Further, the phenolic hydroxyl group-containing component improves the initial adhesive force by the action of the hydroxyl group in the molecule,
Even after the reaction, a hydroxyl group is generated, and a decrease in adhesive strength can be prevented.

[0024]

Examples of the present invention will be described below. 1. Preparation of insulating adhesive solution 100 parts by weight of NBR, 50 parts by weight of bisphenol A type epoxy resin having an epoxy equivalent of 300 to 5000, molecular weight 7
To 100 parts by weight of t-butylphenol, 1 part by weight of ethylene thiourea, and 5 parts by weight of ZnO, 300 parts by weight of cyclohexane was added and dissolved.

2. Production of anisotropic conductive adhesive Anisotropic conductive adhesive was prepared by adding 10 parts by volume of gold-plated acrylic resin particles having a particle diameter of 10 μm to 100 parts by volume of solid content of the insulating adhesive solution prepared above. .

3. Production of heat seal connector A commercially available silver paste (DW-250H-5 manufactured by Toyobo Co., Ltd.) is printed on a flexible base material made of a PET film having a thickness of 25 μm by screen printing, and a conductive line of 0.2 mm pitch is formed. Is formed and then 5 minutes in an oven at 130 ° C.
Dry for a time and cure. Next, the anisotropic conductive adhesive prepared above was applied to the connection terminal portion by screen printing so that the thickness after removing the solvent was 9 μm to form an anisotropic conductive adhesive layer. Was provided, and this was cut into desired dimensions to obtain a heat seal connector.

Next, the heat-seal connector thus obtained was placed between a connection terminal of a transparent conductive oxide film substrate (ITO) having an area resistivity of 50 Ω / □ and an FPC at 160 ° C. and 40 ° C.
The thermocompression bonding was performed under the conditions of kg and 12 seconds, and an environmental test at a high temperature of 110 ° C. to a low temperature of −20 ° C. was performed to measure a resistance value between both connection terminals and a 90 ° peel strength. As shown in Table 1, Was obtained.

[0028]

[Table 1]

[0029]

As described above, the insulating adhesive composition according to the present invention comprises an elastomer component, an epoxy resin, and a phenolic hydroxyl group-containing component as main components, and the elastomer component is an epoxy resin. While improving flexibility and thermal shock resistance, the elastomer component is also cross-linked by a cross-linking agent and a metal oxide to become an elastomer having excellent heat resistance. Further, the epoxy resin reacts with the phenolic hydroxyl group-containing component and cures. However, since the hydroxyl group-containing component is not liquid, its reactivity is low, and it has a long pot life and excellent high-temperature durability.
Furthermore, the phenolic hydroxyl group-containing component functions to improve the initial adhesive force by the hydroxyl group in the molecule, and furthermore, the hydroxyl group is generated even after reacting with the epoxy resin, so that the adhesive force does not decrease and is excellent. The resulting adhesive properties are obtained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a heat seal connector to which an insulating adhesive composition for a heat seal connector according to one embodiment of the present invention is applied.

FIG. 2 is a longitudinal sectional view of the heat seal connector.

FIG. 3 is a longitudinal sectional view of a heat seal connector according to another embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 12 Flexible base material 13 Conductive line 14 Conductive particle 15 Insulating adhesive 17 Insulating resist 15 'Insulating adhesive layer 16 Anisotropic conductive adhesive layer 21 Transparent electrode of ITO substrate

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI H01B 3/28 H01B 3/28 H01R 11/01 H01R 11/01 A // H05K 3/36 H05K 3/36 A

Claims (3)

[Claims] 1. 100 parts by weight of one or more kinds of elastomer components selected from a diene rubber or a styrene-based elastomer, 20 to 150 parts by weight of a solid or semi-solid epoxy resin having an epoxy equivalent of 200 to 5,000, and a molecular weight of 300 20 to 200 parts by weight of one or more kinds of phenolic hydroxyl group-containing components which are 7000 to 7000, 0.1 to 10 parts by weight of a crosslinking agent for crosslinking the elastomer component, and 1 to 50 parts by weight of metal oxide. An insulating adhesive composition comprising: 2. A heat seal connector having a conductive line on at least one surface of a flexible base material and an anisotropic conductive means containing an insulating adhesive and conductive particles provided on at least a portion of the conductive line involved in connection. The composition which constitutes the insulating adhesive comprises 100 parts by weight of one or more kinds of elastomer components selected from diene rubber or styrene elastomer, and epoxy resin 20 to 1 having an epoxy equivalent of 200 to 5000.
50 parts by weight, 20 to 200 parts by weight of one or more phenolic hydroxyl group-containing components having a molecular weight of 300 to 7000, 0.1 to 10 parts by weight of a crosslinking agent for crosslinking the elastomer component, and metal oxide 1 And 50 to 50 parts by weight. 3. The phenolic hydroxyl group-containing component is t-
The insulating adhesive composition according to claim 1, which is at least one selected from butylphenol, poly-p-vinylphenol, and terpene phenol, or the heat seal connector according to claim 2.