JPH0685337B2 - Heat seal connector - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat seal connector used for connecting circuit boards and between the circuit board and input / output terminals of a display such as LCD (liquid crystal display) and PDP (plasma display).

[0002]

2. Description of the Related Art A conventional heat seal connector is shown in FIG.
As shown in Fig. 4, after the conductive pattern b is screen-printed on the flexible film a together with the anisotropic conductive adhesive, the insulating synthetic resin is dissolved and foamed as an insulating resist layer c on the flexible film a. Screen printing of the product with the agent d added, evaporation of the solvent in a drying oven, etc. and foaming of the foaming agent to increase the thickness of the insulating layer to maintain high insulation and prevent migration. Was there.

[0003]

However, in the case where the thickness of the insulating layer is increased by this method, the unevenness of the foaming agent causes an LCD failure.
The slidability with respect to a workbench or a printed circuit board (hereinafter referred to as PCB) is poor, and the workability of aligning the heat seal connector with the terminal electrodes of the glass or PCB is very poor. Therefore, it is an object of the present invention to provide a heat seal connector having improved slidability with respect to an LCD, a PCB or a workbench and an insulation resistance improved by increasing the thickness of an insulating layer.

[0004]

The present invention provides a heat seal connector having a conductive pattern, an anisotropic conductive adhesive portion, and an insulating resist layer (hereinafter referred to as a lower layer resist) on at least one side of a flexible film. An insulating resist layer having a high slidability on the insulating resist layer with respect to a workbench and a printed circuit board (hereinafter referred to as an upper resist layer)
Is formed.

[0005]

In the heat seal connector of the present invention, the insulating resist layers are composed of the upper and lower two layers, and the slidability with respect to the upper workbench and the printed circuit board is improved, so that glass or P
By improving the workability of aligning with the terminal electrode of the CB and increasing the thickness of the insulating layer accordingly, it is possible to improve the surface insulating property and heat resistance in the upper layer and prevent the formation of pinholes in the lower layer. it can.

1 to 3 illustrating the details of the present invention.
Will be described in more detail based on. 1 is a front view showing an embodiment of a heat seal connector of the present invention, FIG. 2 is a partially enlarged vertical sectional view in a direction orthogonal to the conductive line in FIG. 1, and FIG. 3 is a partially enlarged vertical sectional view in another embodiment. It is a figure. In the figure, 1 is a conductive pattern, 2 is an anisotropic conductive adhesive layer, 3 is an upper layer resist, 4 is a lower layer resist, 5 is a flexible film as a base material, 6 is a foaming agent, and 7 is glass beads. . As shown in the figure, the heat seal connector of the present invention comprises a flexible film 5, a conductive pattern 1, an anisotropic conductive adhesive layer 2, a lower layer resist 4 and an upper layer resist 3.

As the flexible film 5 used here, for example, polyimide, polyethylene terephthalate,
Polycarbonate, polyphenylene sulfide, polybutylene terephthalate, polyethylene naphthalate,
Examples thereof include poly-1,4-cyclohexanedimethylene terephthalate, polyarylate, liquid crystal polymer, etc., which are appropriately selected from a film having a thickness of 10 to 50 μm in consideration of flexibility.

The conductive pattern 1 provided on the flexible film is usually formed by forming a paste of a polymer binder and conductive fine powder with an organic solvent, screen-printing this, and then drying the organic solvent. It is what is done. Examples of the polymer binder include vinyl chloride resin, vinyl acetate resin, copolymers thereof, acrylic resin, thermoplastic polyester resin, thermoplastic polyurethane resin, polybutadiene resin, polyimide resin, epoxy resin, alkyd resin, phenol resin. Etc., but if necessary, isocyanates, amines,
You may use together with hardening agents, such as an acid anhydride. As the conductive fine powder, an outer diameter of 0.1 to 100 μm granular, scale-like, plate-like,
Dendritic, dice-shaped silver, silver-plated copper, copper, gold, nickel, and alloys thereof, resin powder plated with one or more of these metals, furnace black,
One kind or two or more kinds of carbon black such as channel black or graphite powder is used, 10 to 90% by weight of the polymer binder is mixed and dispersed, and if necessary, a suitable curing accelerator, a leveling agent, a dispersion stabilizer, Antifoaming agents, thixotropic agents, metal deactivators, etc. are added.

Examples of the solvent for dissolving these include ester-based, ketone-based, ether ester-based, chlorine-based, ether-based, alcohol-based, and hydrocarbon-based solvents such as methyl acetate, ethyl acetate, acetic acid. Isopropyl, isobutyl acetate, butyl acetate, amyl acetate, methyl ethyl ketone, methyl isobutyl ketone, methyl isoamyl ketone, methyl amyl ketone, ethyl amyl ketone, isobutyl ketone, methoxymethylpentanone, cyclohexane, diacetone alcohol, methyl cellosolve acetate, ethyl cellosolve acetate , Butyl cellosolve acetate, methoxybutyl acetate, methyl carbitol acetate, ethyl carbitol acetate, dibutyl carbitol acetate, dibutyl carbitol, trichloroethane, trichloroethylene, n-butyl acetate Le, diisoamyl ether,
n-butyl phenyl ether, propylene oxide,
Furfural, isopropyl alcohol, isobutyl alcohol, amyl alcohol, cyclohexanol, benzene, toluene, xylene, isobrovylbenzene,
Examples include petroleum spirit and petroleum naphtha. Among these, ester-based, ketone-based, and ether ester-based are frequently used. The prepared conductive paste has a viscosity of 50-
1,000 voise, shaking degree (viscosity 20 rotations / 200 rotations) 2-15
It is preferable to adjust The ratio of the solvent component in the conductive paste is 80% by weight or less, preferably 50% by weight or less in consideration of the ability of the member to absorb it, such as thickness and molecular weight.

In the heat seal connector of the present invention, the anisotropic conductive adhesive layer 2 is insulated at the connecting portion on the conductive pattern 1 thus formed, and the conductive pattern 1 is insulated at the remaining portion so as not to be exposed. The resist layers 3 and 4 are formed by screen printing, respectively. The anisotropic conductive adhesive used here is composed of an insulating resin, conductive particles and a solvent. The insulating resin may be thermoplastic or thermosetting as long as it exhibits adhesiveness by heating, and examples of the thermoplastic resin include polyamide-based, polyester-based, ionomer-based, ethylene-vinyl acetate copolymer (EVA), Examples include polyolefin-based materials such as ethylene-methacrylic acid copolymer (EMA) and ethylene-ethyl acrylate copolymer (EEA), various synthetic rubber-based materials, and modified products and composites of these. Examples include synthetic rubbers such as resin-based, urethane-based, acrylic-based, silicone-based, chloroprene-based, nitrile-based and the like, or a mixture thereof, but any of these may be a curing agent, a vulcanizing agent, a control agent, if necessary. , Deterioration inhibitor, heat resistance additive, thermal conductivity improver, tackifier, softening agent, coloring agent, etc. .

As the conductive particles, gold, silver, silver-plated copper,
Metal particles of copper, nickel, palladium, stainless steel, brass, solder, etc., ceramic particles of tungsten carbide, silica carbide, etc., carbon particles, plastic particles whose surface is coated with metal, etc. are used. This particle size is determined in consideration of the application thickness of the insulating resin, the connection pitch of the conductive lines, etc. described above, in consideration of the stability and reliability of connection, the allowable limit of peel strength, etc. Approximately 150 μm is used, and the shape is also spherical, needle-like, scale-like, plate-like, dendritic, dice-like, protruding sphere, irregular shape, etc., considering the stability and reliability of connection. The optimum one is selected. As the solvent that dissolves the insulating resin and the conductive particles, the same solvent as that used in the preparation of the conductive paste for forming the conductive pattern described above is used.

On the other hand, the insulating resist layer is composed of a lower layer resist 4 and an upper layer resist 3. The lower layer resist 4 is made of an insulating resin, a solvent and a foaming agent, and the upper layer resist 3 is made of an insulating resin and a solvent. The insulating resin and solvent used here can be appropriately selected and used for both the upper and lower resists from those used for forming the anisotropic conductive adhesive layer 2 described above. It is preferable that the resist does not exhibit tackiness to some extent, and it is desirable to use the same kind or similar kind for both resists in order to improve the adhesion between the upper and lower resists.
As the foaming agent used for the lower layer resist, a foaming agent that expands to about 20 to 40 μm when heated to 100 to 180 ° C. during solvent drying is used. For example, a copolymer of vinylidene chloride and acrylonitrile is used. As a shell,
Examples of the swelling agent include those encapsulating by encapsulating isobutane.

As described above, in the heat seal connector of the present invention, the upper layer resist is required to have high slidability with respect to the workbench and the printed circuit board. This slidability has a friction coefficient specified by JIS K-7125 in order to improve the alignment work during heat sealing.
It is necessary to set it to 0.5 or less, and in order to satisfy this, the insulating resin is not particularly limited, but it is a polyamide type, polyester type, etc. and has a high glass transition temperature (T _g ). It is desirable to select a material having a high hardness at room temperature. Further, a fluorine resin may be added to this, or particles having good slidability, such as glass beads, may be added thereto. When these resins are made into a solution, if the concentration is too low, a sufficient thickness cannot be obtained, and if too high, warpage occurs due to shrinkage during drying, so the concentration of the solution is adjusted to 5 to 50%. It On the other hand, since these resins have low viscosity and poor printability when made into a solution, it is possible to improve the printability by adding 0.1 to 10% by weight of synthetic rubber such as NBR, CR and SBR. If the amount added is less than 0.1% by weight, the printability is not improved, and if it exceeds 10% by weight, the slidability is deteriorated. The coating thickness of the upper layer resist is preferably formed so as to cover the irregularities of the foaming agent in the lower layer resist.

[0014]

EXAMPLES Specific embodiments of the present invention will be described below with reference to Examples and Comparative Examples. Example 1 A 25 μm thick polyester film, Lumirror (trade name, manufactured by Toray Industries, Inc.) was used as a flexible film, and silver / carbon paste XA-256C was used as a conductive paste on one surface of the film.
(Fujikura Kasei Co., Ltd., trade name) was used to form a conductive pattern by a screen printing method. Next, phenol resin is used as an electrically conductive particle that contributes to the electromechanical connection between the SBR synthetic rubber and the input / output terminals of the other substrate at the electromechanical connection portion of the upper surface of the other substrate with the input / output terminals. An anisotropic conductive adhesive consisting of a gold-plated product and titanium white as an extender pigment was screen-printed to form an anisotropic conductive adhesive layer. To the remaining portion, a polyester resin to which a foaming agent capable of foaming by heating was added was similarly screen-printed to form a lower layer resist. On top of it, the average particle size of 17 μ
The glass beads to which m 2 was added were similarly screen-printed to form an upper layer resist to obtain a heat seal connector of the present invention.

Example 2 The same processes as in Example 1 were carried out until formation of the lower layer resist, and then
Insulating resist of polyester resin, DOTITE XB-10
1 G (Fujikura Kasei Co., Ltd., trade name) was screen-printed to form an upper layer resist, and a heat seal connector of the present invention was obtained.

Comparative Example A heat seal connector was obtained in the same manner as in Example 1 except that the upper layer resist was not formed.

For each of the obtained heat-sealed connectors, the coefficient of friction specified by JIS K-7125, workability, and resist surface insulation by the following measuring method were measured,
The results are shown in Tables 1 and 2. From this, the heat seal connector of the present invention was excellent in slidability and surface insulation.・ Measurement method of resist surface insulation: Heat seal one side of the heat seal connector to PCB, put a metal electrode with a weight of 500g on the insulation resist, and insulate by applying voltage for 10 seconds between metal electrode and PCB. It is expressed by the voltage when the breakdown occurs.

[0018]

[Table 1]

[0019]

[Table 2]

[0020]

According to the heat-seal connector of the present invention, since the insulating resist is composed of the upper and lower layers, the lowering of the slidability of the lower layer resist can be prevented, and the heat-sealing cycle time can be shortened. Cost reduction can be realized. In addition, since the thickness of the insulating resist layer can be increased, surface insulation is improved, moisture ingress can be suppressed, migration resistance is improved, and the same type of resin is used for both upper and lower insulating resist layers. This improves the adhesion between the upper and lower insulating resists.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of a heat seal connector of the present invention.

FIG. 2 is a partially enlarged vertical sectional view of the heat seal connector shown in FIG. 1 in a direction orthogonal to a conductive line.

FIG. 3 is a partially enlarged vertical sectional view showing another embodiment of the heat seal connector of the present invention.

FIG. 4 is a partially enlarged vertical sectional view of a conventional heat seal connector.

[Explanation of symbols]

1 ... Conductive pattern, 2 ... Anisotropic conductive adhesive layer, 3 ... Insulating resist layer (upper layer resist), 4 ...
Insulating resist layer (lower resist), 5 ... Flexible film, 6 ... Foaming agent, 7 ... Glass beads.

Claims (1)

[Claims] 1. A heat seal connector having a conductive pattern, an anisotropic conductive adhesive layer, and an insulating resist layer on at least one side of a flexible film, which is highly slidable on a work table and a printed circuit board on the insulating resist layer. A heat-seal connector, wherein an insulating resist layer having mobility is formed.