JPH0713901B2 - Heat seal connector - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a liquid crystal display (L
CD), electroluminescence (EL), light emitting diode (LED), electrochromic display (ECD), plasma display (PDP) display terminal connection terminals, and a circuit board on which the drive part is mounted, or various electric circuit boards. The present invention relates to a heat seal connector used for connecting between connection terminals.

[0002]

2. Description of the Related Art Conventionally, heat seal connectors have been
It is used for connecting a display body such as CD, EL, LED, ECD, PDP and the like to a hard printed wiring board (PCB) or a flexible printed board (FPC), or a connection between PCB and FPC. The conventional heat seal connector has an anisotropic conductive property in which a desired pattern is formed on an insulating flexible base material with a conductive paste, and conductive fine particles are dispersed and mixed in the insulating adhesive. Those having an adhesive layer are known (Japanese Patent Publication No. 55-38073, Japanese Patent Publication No. 58).
-56996 etc.).

However, with the recent miniaturization and refinement of electric and electronic devices, the pitch of the connection terminals required for the heat seal connector has been reduced to 0.3 mm and 0.2 mm. In such a case, in the type in which the above conductive fine particles are dispersed and mixed in the insulating adhesive, the conductive fine particles easily cause a short circuit between the patterns. It has been proposed that a conductive paste is dispersed and mixed, and an insulating adhesive layer is provided on the conductive paste (Japanese Patent Laid-Open No. 62-500828, Japanese Patent Laid-Open No. 62-1).
54746 for example).

[0004]

SUMMARY OF THE INVENTION In the above conventional configuration,
In each case, as shown in FIG. 3, conductive fine particles 2 for electrically connecting the pattern made of the conductive paste 3 provided on the insulating flexible substrate 1 and the connection terminal 5 such as ITO.
The existence of a was essential. In the figure, 4 is an insulating adhesive. Conductive fine particles include precious metal fine particles such as Au, Ag and Pt, fine metal particles such as Ni, Al and Fe, and those having their surfaces plated with precious metals, carbon black, black powder and carbon fiber. Those having high hardness are used.

However, such conductive fine particles cannot easily follow the amount of deformation / flow displacement of the insulating flexible base material, conductive paste and insulating adhesive layer due to heating / pressurizing during heat sealing, Under various environments that are set after connection, microscopic movement of the conductive fine particles under the residual stress of the insulating flexible base material, the conductive paste and the insulating adhesive layer occurs, causing partial disconnection and high There is a risk that resistance may be changed and seriously adversely affect the reliability of electrical continuity.

In order to avoid the above danger, conductive fine particles having a low hardness insulating plastic elastic body as a core and plated with a precious metal on the surface have been proposed. During heating / pressurization, the hardness difference between the precious metal and the insulating plastic elastic body causes minute cracks on its surface, and during plating, the surface of the insulating plastic elastic body to which electrolytes and ions are attached is exposed. There is also a possibility that problems such as electrolytic corrosion due to ions may occur. Further, since the precious metal is used, the manufacturing cost is high and there is a problem in mass production.

The present invention solves the above-described conventional problems, and does not require the use of conductive fine particles for electrically connecting the connection terminal and the pattern to each other under various environments after heating / pressurizing connection. It is an object of the present invention to provide a heat-seal connector having high reliability and electrical conductivity at low cost.

[0008]

As a result of earnest studies on the means for solving the above-mentioned problems, the present inventor has found that the connection terminals, which have been indispensable up to now, in the electrical connection structure between various connection terminals and patterns. And without using separate conductive fine particles that form an electrical connection between the pattern and the conductive paste, the insulating fine particles are mixed in the conductive paste, and the coating of the conductive paste coating the insulating fine particles is projected to connect. The inventors have found that a higher reliability of electrical continuity after connection can be ensured by directly connecting the terminals to each other, and thus the present invention has been achieved. Pattern is formed of a conductive paste having a protruding coating that coats the insulating fine particles, and at least the connection terminal portion of the pattern is coated with an insulating adhesive layer. The gist of the over door seal connector.

In the heat-seal connector of the present invention, the pattern is lifted by the insulating fine particles which are dispersed and blended in the conductive paste forming the pattern, and the embedded fine particles are formed in the pattern, and the projecting portion is formed. It is intended that the protruding coating (conductive paste) of (3) directly contacts the opposing connection terminal for electrical connection. At this time, the compressive strength of the insulating fine particles buried in the pattern can be arbitrarily selected depending on the heating / pressurizing conditions at the time of connection, but at least has a strength range that does not break through the conductive paste film at the time of pressing the connection. Is essential, and more preferably, it has rubber elasticity. This is because the amount of deformation of the insulating fine particles during heating / pressurization is required to follow that of the conductive paste.

As the conductivity-imparting agent in the material constituting this conductive paste, granular, scaly, plate-shaped, dendritic, dice-shaped Ag, Ag-plated Cu, Cu, Au, Ni, Pd, and These alloys, resin powders plated with one or more of these metals, carbon black such as furnace black and channel black, and ones using one or more of graphite powders are mentioned. It is dispersed and compounded at a ratio of 10 to 90 wt% with respect to the organic binder.

A resin composition such as a thermoplastic or thermosetting resin is used as the insulating organic binder in which the conductivity-imparting agent is dispersed, but it is resistant to heat, particularly to heating / pressurizing at the time of connection. It is preferable to use a thermosetting resin in order to obtain it. If necessary, a curing accelerator, a leveling agent, a dispersion stabilizer, an antifoaming agent, a thixotropic agent, etc. may be appropriately added.

Further, when an inorganic substance such as glass, talc, silica, or ceramic is used as the main material for the insulating fine particles, the particles may be crushed at the time of connection by heating and pressurizing, and the crushing does not occur. Even when pressed in the vertical direction, if there is a risk of breaking through the film of the conductive paste due to the difference in hardness, the insulating fine particles include polymethylmethacrylate, polyamide, polystyrene, benzoguanamine, phenol, epoxy, aramid. An elastic resin composition such as a plastic elastic body such as acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), silicone rubber (SR) or an elastomer is preferably used alone or as a coating.

The insulating fine particles are appropriately selected from a particle shape, a plate shape, a dendritic shape, a dice shape and the like.
A granular material in which the load is easily dispersed on average is particularly preferable. Further, if it is made of a resin, it has an advantage that its shape and elasticity can be controlled by its polymerization method.

In order to obtain a stable connection by embedding and fixing such insulating fine particles in the conductive paste, the number of particles is 20 per 1 mm ² of the connection terminal portion of the pattern formed by the conductive paste. The number of particles or more, preferably 50 or more, may be set, but the particle size (r) at that time is
It is determined by the relationship between the line width T _C and the thickness of the pattern (t). That is, if r is too small with respect to t, it becomes difficult to form a convex portion, so r ≥ (2/3) t, preferably r ≥ t
If r is larger than Tc, it becomes difficult to form a pattern physically, so r <Tc, preferably r <(1 /
2) It should be Tc.

In order to prevent the insulating fine particles from breaking through the conductive paste film during heating and pressurization,
The difference between the SP value on the surface and the SP value of the organic binder in the conductive paste is preferably at least 2 and more preferably 1 or less. As a result, the surface of the insulating fine particles and the organic binder are well wetted and high adhesion can be obtained.

It is necessary to provide an insulating adhesive layer in order to firmly connect the desired pattern formed on the insulating flexible base material using these conductive paste and insulating fine particles to the opposing connection terminals. There is. The main component of this insulating adhesive is ethylene-vinyl acetate copolymer, carboxyl-modified ethylene-vinyl acetate copolymer, ethylene-acrylate copolymer, ethylene-ethyl acrylate copolymer, ethylene-isobutyl acrylate copolymer. Coalesce, polyamide, polyester, polymethylmethacrylate, polyvinyl ether, polyvinyl butyral, polyurethane, SBS copolymer, carboxyl modified SBS copolymer, styrene-isoprene-styrene (SIS) copolymer, styrene-ethylene-butylene-styrene ( SEB
S) copolymer, maleic acid modified SEBS copolymer, polybutadiene rubber, CR, carboxyl modified CR, styrene-butadiene rubber, isobutylene-isoprene copolymer, NBR, carboxyl modified NBR, epoxy resin,
It is obtained by one kind or a combination of two or more kinds selected from SR and the like.

As the tackifier, rosin,
Rosin derivative, terpene resin, terpene-phenol copolymer, petroleum resin, coumarone-indene resin, styrene resin, isoprene resin, alkylphenol resin,
Phenolic resin and the like are appropriately added as necessary as one kind or a combination of two or more kinds. Also, a reactive aid,
Phenolic resins as crosslinking agents, polyols, isocyanates, melamine resins, urea resins, urotrobins, amines, acid anhydrides, peroxides, metal oxides, organic acid metal salts such as trifluoroacetic acid chromium salt, titanium , Alkoxides such as zirconia and aluminum, organometallic compounds such as dibutyltin oxide, photoinitiators such as 2,2-diethoxyacetophenone and benzyl, and sensitizers such as amines, phosphorus compounds and chlorine compounds, if necessary. Is appropriately selected and used. Furthermore, these include hardeners,
Vulcanizing agents, control agents, deterioration inhibitors, heat resistance additives, thermal conductivity improvers, softeners, colorants, various coupling agents, metal deactivators and the like may be added as appropriate.

The insulating flexible base material of the heat seal connector of the present invention includes polyimide, polyethylene terephthalate, polyethylene naphthalate (PEN), polybutylene terephthalate, polycarbonate, polyphenylene sulfide, poly-1,4-cyclohexane dimethylene terephthalate. , A polyarylate, liquid crystal polymer, etc., using a polymer film having a heat resistance of 10 to 50 μm and having insulating fine particles dispersed and blended thereon, screen printing, gravure printing, etc. After forming a desired pattern by a known printing method, at least a connecting terminal portion of the pattern with an insulating adhesive,
The heat-sealing connector of the present invention can be obtained by coating using the known printing method, roll coating, bar coating, knife coating, spray coating, spin coating, or the like.

When a pattern is formed using a known printing method, screen printing is particularly preferable in order to obtain a target thickness with one coating without crushing the insulating fine particles. The screen material used for this is generally a plain weave or twill weave of an iron alloy such as stainless steel having a wire diameter of 10 to 40 μm, and an electroformed plate formed in a grid pattern by nickel plating etc. stretched on a rigid frame. Used to form a precise circuit pattern, thin the wire so that the opening of the mask material such as acrylic, that is, the opening approximately equal to the shape of the desired pattern is not blocked by the wire or the intersection of the wire. It will be necessary to have a thick (T _S )
Is inevitably thin, but the ratio of T _S to the aperture ratio (φ) is preferably 0.8 or more, more preferably 1.5 or more from the viewpoint of the permeability of the conductive paste. It is necessary to increase the strength of the wire rod and reduce the wire diameter without dropping, and φ is preferably 35% or more, and more preferably 60% or more.

The above equation will be described in more detail with respect to the thickness. In the case of T _C ≧ 0.3 mm, r ≧ 2/3 {(T _S + T _N ) × φ × V / 100}, preferably r It is preferable that ≧ (T _S + T _N ) × φ × V / 100. However, when T _N : emulsion thickness, V: volume solid content of conductive paste, and T _C <0.3 mm, the conductive paste laterally sags (spreads laterally) immediately after printing, so r ≧ 2/3 {( T _S + T _N ) × φ × V / 100} × 0.6 to r ≧ {(T _S + T _N ) × φ × V / 100} × 0.8 may be designed.

[0021]

The heat-sealing connector of the present invention is constructed as described above, and is dispersed and mixed in the conductive paste forming the pattern, and the embedded fine particles are embedded and fixed to form a protruding portion on the pattern, which is used when connecting. By conducting the heating / pressurizing operation, the electrically conductive paste in the protruding portion is brought into direct contact with the opposing connecting terminal so that electrical conduction is achieved. As described above, in the present invention, since the connecting terminals are directly contacted and electrically connected to each other, there is no possibility of a short circuit between the connecting terminals, and since the insulating fine particles are used, there is no possibility of causing electrolytic corrosion. Since the presence of the insulating adhesive layer firmly holds the adhesive structure between the connection terminals, the advantage that the reliability of electrical conduction can be improved in various environments is given.

[0022]

Embodiments of the present invention will be described below with reference to FIGS. Preparation of conductive paste containing insulating fine particles As an organic binder, 70 parts by weight of scale-like Ag powder and 3 parts by weight of amine curing accelerator to 100 parts by weight of thermosetting resin containing bisphenol A type epoxy resin as a main component. Department,
After dissolving 1 part by weight of each of the leveling agent, dispersion stabilizer, antifoaming agent and thixotropic agent in a mixed solvent of toluene: MEK = 7: 3, the compressive strength at 10% deformation was 3.9 kgf / mm ^2. Thirty parts by volume of vulcanized phenolic resin elastic fine particles (average particle diameter of about 20 μm) were added to prepare a conductive paste containing insulating fine particles. The compressive strength of this conductive paste at 10% deformation is 5.0k.
It was gf / mm ² .

Preparation of Insulating Adhesive Solution For each 100 parts by weight of carboxyl-modified NBR, 40 parts by weight of an alkylphenol-based tackifier, 1 part by weight of a deterioration inhibitor, a heat-resistant additive, and 1 part by weight of an amine-based silane coupling agent were added, and petroleum oil It was dissolved in a mixed solvent of naphtha: butyl carbidol = 1: 1 to prepare a 35% by weight insulating adhesive solution.

Next, as shown in FIG. 1, a P layer having a thickness of 25 μm is used.
On the insulating flexible substrate 1 made of an EN film, the conductive paste 3 containing the insulating fine particles 2b prepared above was used, and the thickness after drying was 0.3 mm so that the thickness after drying was 25 μm. Pitch pattern 3 was formed by screen printing. Then, the insulating adhesive prepared above was applied to the entire surface so that the thickness after removal of the solvent would be 10 μm.
It was applied with a bar coater and dried to form an insulating adhesive layer 4, which was cut into desired dimensions to obtain a heat seal connector of the present invention.

[0025]

[Comparative example] Instead of the vulcanized phenolic resin elastic fine particles 2 in the conductive paste 3 prepared above, the compressive strength at 10% deformation is 16.3 kgf / mm ² , and the average particle size is about 20 μm.
A heat-sealed connector was obtained in the same configuration as in Example except that the Ni-plated Ni particles were used.

The heat-sealed connector thus obtained is
As shown in FIGS. 2A, 2B, and 2C, the sheet resistivity is
30Ω transparent conductive oxide film substrate (ITO) connection terminal 5,
Heat seal under conditions of 140 ℃, 30kg / cm ² , 12scc, and heat shock test (85 ℃, 30min and -30 ℃, 30min alternately 10
(Repeat 00 times) and the change in the resistance value between both connection terminals, and the relationship between the time the product was left in an environment of 60 ° C and 95% RH and the change in resistance value between both connection terminals The results are shown in Table 1 and Table 2, respectively. When conductive fine particles are used instead of insulating fine particles, the high resistance value from the initial stage of connection is considered to be because the contact resistance between the conductive fine particles and the organic binder contributes more, and the resistance value changes with time. The larger rise is considered to be due to electrolytic corrosion due to contact with the connection terminal.

[0027]

[Table 1]

[0028]

[Table 2]

[0029]

As described above, when the heat seal connector of the present invention is used, there is no risk of short-circuiting even in connection terminals of fine electric / electronic circuits, etc., and the conductive paste contains insulating fine particles. By the heating / pressurizing operation, the protruding portions can be reliably connected to the opposing connection terminals, and the reliability of electrical continuity can be improved even in the severe conditions such as outdoors in the summer, inside the vehicle, and underwater. In addition, since no precious metal or conductive fine particles plated with precious metal is used, it is chemically stable without residual deposits of electrolytes and ions, and no special equipment or jigs are required during manufacturing. So
It is possible to provide an inexpensive heat seal connector.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a heat seal connector of the present invention.

FIG. 2A is a connection explanatory view of a heat seal connector of the present invention and a pattern ITO glass connection terminal, FIG. 2B is a vertical sectional view taken along line XX of FIG. 2A, and FIG. ) Y
-A vertical cross-sectional view taken along the line Y.

FIG. 3 is a connection explanatory view of a conventional heat seal.

[Explanation of Codes] 1 ... Insulating flexible base material 2a ... Conductive fine particles 2b ... Insulating fine particles 3 ... Conductive paste 4 ... Insulating adhesive layer 5 ... ITO connection Terminal

Claims (1)

[Claims] 1. A desired pattern is formed on an insulating flexible substrate with a conductive paste having a protruding coating for covering insulating fine particles, and at least a connecting terminal portion of the pattern is covered with an insulating adhesive layer. Heat seal connector that is characterized by being.