JPH07169522A - Flat panel display - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a flat panel display device provided with means for easily connecting terminals of a flat panel and terminals of a circuit for supplying a signal to the panel without misalignment or poor contact. To do. A flexible printed board having a scanning electrode (or signal electrode) terminal portion 6 of a flat panel display element, a conductor electrode 15 to be connected to the terminal portion 6, a synthetic resin adhesive 16 and metal particles 17. Containing metal particles 17
Particle diameter d _M of the display element and the film thickness dt of the terminal portion 6 of the display element and the film thickness dc of the conductor 15 to be connected are formed so as to have the relationship of A flat panel display device comprising a polymer film 18 which is sandwiched between a terminal portion of an electrode and a conductor to be connected and which is subjected to heat and pressure to connect the terminal portion and the conductor. 0.905d _M ≤ dt + dc ≤ 1.04d _M

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a connection structure for a flat panel display device, and more particularly to a connection structure for a flat panel display device using a thermocompression bonding method for connecting terminals.

[0002]

2. Description of the Related Art In flat panel display devices such as liquid crystal display devices, fluorescent display devices, electroluminescence display devices, and plasma display devices, there is a tendency toward higher definition and larger capacity, and problems with the formation of electrodes are The connection of terminals has become a big problem, and various connection methods have been proposed.

One method is to use a pressure contact type connector utilizing rubber elasticity. This pressure contact type connector can be roughly classified into three types. First, a conductive rubber has conductivity and a spring function. Secondly, the conductive rubber is not used, but metal, carbon fiber, carbon paint or the like is used as the conductor, and the insulating rubber as the binder or the support material functions as the spring. The third is an anisotropic conductive rubber having a characteristic that an electric current flows only in the thickness direction and does not flow in a direction perpendicular to the thickness.

These pressure contact type connectors are used for small liquid crystal displays such as watches and calculators. However, the connection accuracy of this type of pressure contact type connector is as low as about 2 wires / mm at present, and it cannot be applied to a high definition and large capacity flat panel display device.

Therefore, a method of melting solder by infrared rays has been proposed as an effective connection method for a high-definition and large-capacity flat panel display device. The connection accuracy of this method is about 4 wires / mm.

However, in this method, since the solder is melted and connected by infrared rays, it is difficult to determine the connection conditions such as the amount of heat, the shape of the solder, and the elongation of the object to be connected.
There is a drawback that the electrode formation becomes complicated.

[0007]

From such a situation,
As a simple connection method for a high-definition and large-capacity flat panel display device, Japanese Patent Publication No. 58-56996, Japanese Patent Publication No. 59-2179, Japanese Patent Publication No. 51-20941, and Japanese Patent Publication No. 52-41648 are available. Publication, JP-A-51-11
No. 4439, No. 51-119732, No. 51-135938, No. 51-2119.
As described in Japanese Patent Publication No. 2, a heat seal connector, that is, a connector utilizing a thermocompression-bonding type connector for applying heat and pressure to a polymer film in which a conductive substance is dispersed in an adhesive layer to connect the polymer film is proposed. ing.

A characteristic of the connection structure using the heat seal connector is a conductive substance dispersed in the adhesive layer. Cu, solder, Ni, carbon, etc. are used as the conductive material. A major factor that determines the connection accuracy of the connection method using the heat seal connector is the shape and size of the conductive material.

According to the connecting method using the heat-sealing connector, the electrodes are pressed against each other via the conductive substance, so that the electrode material is not limited and the electrodes can be easily formed.

However, in the connection method using the heat-seal connector, several tens of kg per unit area under heat is applied.
Since the pressure is applied, a contact failure such as a short circuit or a positional shift between the adjacent terminals, which electrically connects the adjacent terminals, easily occurs. Further, there is a problem in that the contact resistance varies depending on the connection conditions and the flatness of the thermocompression bonding device.

An object of the present invention is to provide a flat panel display device having means for easily connecting terminals of a flat panel and terminals of a circuit for supplying a signal to the flat panel without causing misalignment or poor connection. Is to provide.

[0012]

In order to achieve the above object, the present invention has a plurality of scanning electrodes and a plurality of signal electrodes, and displays image information according to an electric signal applied to the scanning electrodes and the signal electrodes. A flat panel display element, a flexible printed board having a conductor to be connected to a terminal portion supplying an electric signal to a scanning electrode or a signal electrode of the flat panel display element, a metal particle containing a synthetic resin adhesive and metal particles Particle size d _M and the film thickness d of the terminal portion of the display element
t and the film thickness dc of the conductor to be connected are formed so as to have the following relationship, and have conductivity in a directionality, and are sandwiched between the terminal portion of the scan electrode or the signal electrode and the conductor to be connected to generate heat. The present invention proposes a flat panel display device comprising 0.905 d _M ≤dt + dc ≤1.04 d _M and a polymer film which is pressed to connect a terminal portion and a conductor.

In the present invention, in order to achieve the above object, the particle diameter d _M of the metal particles and the film thickness d of the terminal portion of the display element.
In addition to the relationship between t and the film thickness dc of the conductor to be connected,
Terminal pitch Lp of terminals of the display element and terminal gap L
It proposes a flat panel display device formed so that q has the following relationship.

0.5 Lp≤Lg≤0.6 Lp

[0015]

In the present invention, the particle diameter d _M of the metal particles, the film thickness dt of the terminal portion of the display element, and the conductor film thickness d to be connected.
Since c and C have the following relationship, the original particle diameter can be maintained without crushing the metal particles dispersed between adjacent terminals during thermocompression bonding. Therefore, a so-called short circuit between adjacent terminals in which the metal particles dispersed between the adjacent terminals electrically connect the adjacent terminals does not occur.

0.905d _M ≤ dt + dc ≤ 1.04d _{M In} addition to the relationship between the particle diameter d _{M of the} metal particles and the film thickness dt of the terminal portion of the display element and the conductor film thickness dc to be connected, Terminal pitch Lp and terminal gap L
Since q is configured to satisfy the following equation, even in a flat panel display device such as a thermal writing liquid crystal display device that conducts a relatively large current, it is dispersed between adjacent terminals during thermocompression bonding. The original particle size can be maintained without the metal particles being crushed. Therefore, a so-called short circuit between adjacent terminals in which the metal particles dispersed between the adjacent terminals electrically connect the adjacent terminals does not occur.

0.5 Lp≤Lg≤0.6 Lp

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the flat panel display connection structure according to the present invention will be described with reference to FIGS.

FIG. 4 is a micrograph showing the dispersion state of metal particles in a polymer film as an anisotropic conductive film according to the present invention, and FIG. 5 shows a connection method using the polymer film according to the present invention. It is a figure which shows typically.

In FIGS. 4 and 5, the polymer film 1 which is an anisotropic conductive film is composed of a mixture of a polyolefin rubber and a synthetic resin having an adhesive function, and a molten metal 2 having an electrically conductive function. . The film thickness of the polymer film 1 which is an anisotropic conductive film is about 30 microns, and the particle diameter of the molten metal 2 is about 20 microns. Also, the polymer film 1
Has a curing temperature of 170 ° C., and the melting point of the molten metal 2 is
It is 190 ° C. In the present example, the reason for using the molten metal 2 as the conductive material of the polymer film 1 is that the contact area can be increased and the contact resistance at the time of connection can be reduced, and that a relatively large current can be applied to the connection portion.

Although the molten metal 2 is used in this embodiment, when the present invention is carried out, the electric resistance of carbon, carbon fiber, nickel particles, copper particles, solder particles and the like is low and the particle diameter is small. Any material can be used as a conductive material in the polymer film 1.

The polymer film 1 shown in FIG. 4 has a diameter of 2 as metal particles in a synthetic resin adhesive having a thickness of about 30 μm.
The solder particles 2 of about 0 micron are dispersed.

More specifically, FIG. 5 schematically shows a connection method in which the present invention is applied to a thermowriting liquid crystal display device utilizing the thermo-electro-optical effect of smectic A-phase liquid crystal which is a relatively severe condition for terminal connection. FIG. here,
The polymer film 1 shown in FIG. 4 is sandwiched between the connection terminal of the liquid crystal display element 3 and the FPC, that is, the flexible printed circuit 4, and heat and pressure are simultaneously applied to the connection terminal of the liquid crystal display element 3 and the FPC 4. Connect with the connection terminal.

FIG. 1 is a diagram showing a schematic structure of a liquid crystal display device to be connected according to the present invention together with a polymer film according to the present invention. In the electrode of the thermal writing display element utilizing the thermo-electro-optical effect of the smectic A-phase liquid crystal, the scanning electrode 6 is composed of a resistor and the signal electrode 7 is composed of a transparent conductor in order to heat the liquid crystal layer. There is. Scan electrode 6 is 85% A
1-10% Si-5% Cu alloy with a film thickness of 1 μm,
Sheet resistance is 0.17Ω / sq ・, diffuse reflectance is 68%
(λ = 400 nm). On the other hand, the signal electrode 7 is indium oxide, has a film thickness of 1000Å and a sheet resistance of 30Ω.
/ Sq., The transmittance is 90%.

A liquid crystal 8 is formed on the scanning electrodes 6 and the signal electrodes 7.
Alignment films 9 for controlling the arrangement state are formed respectively, and the liquid crystal 8 is sandwiched between the scanning electrode substrate 10 and the signal electrode substrate 11. The support material 13 is dispersed in the sealant 12, and the support material 13 is also dispersed in a portion corresponding to the display surface to control the thickness of the liquid crystal layer 8.
It is uniform.

The liquid crystal 8 of this embodiment is an acyloxy type liquid crystal and is a mixture of (1), (2) and (3) of the following structural formulas in a weight ratio of 1: 1.

[0027]

[Chemical 1]

The phase transition temperature Tcs of the liquid crystal 8 from the solid to the smectic A phase is 10 ° C., the phase transition temperature T _SN of the smectic A phase to the nematic phase is 45 ° C., and the nematic phase to the liquid phase. The transition temperature T _N1 is 47 ° C. Further, the relative permittivity ε _{1 in} the short axis direction of liquid crystal molecules at 25 ° C. is 6.59, and the relative permittivity ε ₁₁ in the long axis direction is
16.76, and the difference Δε between the relative permittivity ε ₁₁ in the major axis direction and the relative permittivity ε _{1 in the} minor axis direction is 10.17, and the relative permittivity ε ₁₁ in the major axis direction and the minor axis direction are Of the relative permittivity of ε ₁ to ε ₁₁
/ Ε ₁ is 2.54.

The alignment film 9 for controlling the alignment state of the liquid crystal 8 is
Shin-Etsu Chemical Model LP-8 Fluorine-based silane C ₈ F ₁₇ (CH ₂ )
It includes _{2 Si (OCH 3) 2 CH} 3 and Tokyo Ohka Kogyo Co., Ltd. silanol oligomer [Name Si film (model number 59000)] and mixtures, the mixing ratio thereof with respect to 100 parts polyetheramide, fluorine silane and Si The mixture of films is 1.8 parts.

The liquid crystal 8 and the alignment film 9 for carrying out the present invention are not limited to the above embodiments. That is, if the respective mixing ratios are changed according to the use environment, driving conditions, etc., it is possible to set the phase transfer temperature, relative permittivity, orientation regulating force, etc. to optimum values.

The liquid crystal 8 of this embodiment was mixed with a black dichroic dye in order to perform a positive display, and was used as a guest-host type liquid crystal. This black dichroic dye is LSR-310, LSY-108, LSB-31 manufactured by Mitsubishi Kasei.
8 and LSB-278 are mixed, and the mixing ratio is SLR-310: 40 parts, LSY-10.
8:80 parts, LSB318: 80 parts, LSB-278:
It is 100 copies. The liquid crystal 8 is 1.7 parts of the black dye with respect to 100 parts of the smectic A-phase liquid crystal.

For the scanning electrode substrate 10 and the signal electrode substrate 11, soda glass with a thickness of 1.1 mm was used, and the sealant 1
An epoxy type was used for 2, and a glass fiber having a diameter of 12 μm and a length of about 80 μm was used as the support material 13 dispersed in the sealant 12 and the support material dispersed in the display surface.

FIG. 2 is a diagram showing the states of terminals and electrodes of the liquid crystal display device for thermal writing connected by the polymer film of the present invention, and FIG. 3 is a perspective view showing the state before connection of FIG. Is. According to the embodiments shown in FIGS. 2 and 3, in the connection method using a polymer film for the liquid crystal display device for thermal writing, an electrical short circuit between adjacent terminals and a terminal of the display device and F can be performed.
It is possible to prevent the positional deviation from the terminals of the PC, reduce the contact resistance, and increase the current carrying capacity. The detailed reason will be described later with reference to FIGS.

In FIG. 3, the flexible printed circuit board 4 has electrodes 15 on the base film 14, and the circuit conductor 20 is exposed on the rigid substrate 19 on the liquid crystal display element 3 side. In order to connect the electrode 15 and the circuit conductor 20 to each other, the polymer film 18 is placed on the circuit conductor 20 and the flexible printed circuit board 4 is overlapped to connect the circuit conductor 20 and the electrode 15 in the same manner as described above with reference to FIG. Align and apply heat and pressure.

The structure shown in FIG. 2 has a FP and a terminal portion of the scanning electrode for supplying a relatively large current to heat the liquid crystal layer.
The structure is suitable for connection with C, and the pitch of the scanning electrodes is 2
The target specifications are 50 μm (definition: 4 lines / mm), energizing current: 1 A, contact resistance: 1 Ω or less. As described above, the adhesive 1 is provided between the scan electrode 6 formed on the scan electrode substrate 10 and the electrode 15 formed on the base film 14 of the FPC 4.
In order to optimally connect the polymer film 18 composed of 6 and the metal particles 17 by applying heat and pressure, the electrode 1 of the FPC 1
The relationship between the sum of the film thickness of 5 and the film thickness of the scanning electrode 6 and the size of the metal particles 17 dispersed in the polymer film is important. Furthermore, in order to prevent a short circuit between adjacent terminals, the scan electrode 6
The size of the gap between them is also an important factor.

FIG. 6 shows a state before connection of a defect example in which the particle diameter of the metal particles 17 of the polymer film 18 is larger than the thickness of the scanning electrode 6 and the conductor electrode 15 of the FPC 4 added. FIG. 7 is a diagram showing a state after connection of the defect example of FIG. When the size of the metal particles 17 of the polymer film 18 is larger than the total thickness of the scanning electrode 6 and the electrode 15 of the FPC 4, the metal particles 17 dispersed between the adjacent terminals are crushed. Contact failure occurs due to spread and short circuit between adjacent terminals.

In the state before connection in FIG. 6, the FPC including the base film 14 and the electrode conductor 15 and the glass substrate 10 are connected.
The adhesive 16 is provided between the scanning electrode substrate including the scanning electrode 6 and the scanning electrode 6.
The polymer film 18 including the metal particles 17 is sandwiched, and heat and pressure are applied to connect them.

In the state after connection in FIG. 7, the conductor 1 of the FPC is
Since the particle size of the metal particles 17 is larger than the sum of the film thickness of the scanning electrode 6 and the film thickness of the scanning electrode 6, the metal particles 17 dispersed between the adjacent terminals are crushed and spread, and the FPC conductor 15 is also spread.
The metal particles 17 that conduct between the scanning electrode 6 and the scanning electrode 6 are further strongly crushed and spread, and are melted and integrated with the crushed metal particles 17 between the adjacent conductors, resulting in a short circuit between the adjacent conductors. To do.

FIG. 8 is a diagram showing a state before connection in a preferred example in which the particle diameter of the metal particles of the polymer film is smaller than the thickness of the scanning electrode and the conductor electrode of the FPC. Yes,
FIG. 9 is a diagram showing a state after connection of the preferred example of FIG.

In the state before connection in FIG. 8, a polymer film composed of an adhesive 16 and metal particles 17 is provided between the FPC 4 composed of the base film 14 and the electrode conductor 15 and the rigid substrate composed of the glass substrate 10 and the scanning electrode 6. Sandwich 18
Connect by applying heat and pressure.

In the state after connection in FIG. 9, since the particle size of the metal particles 17 of the polymer film is smaller than the total thickness of the conductor 15 of the FPC 4 and the film thickness of the scanning electrode 6, the size of the metal particles 17 between adjacent terminals is small. The metal particles 17 dispersed in can be maintained in the original particle diameter without being crushed. Therefore, since the particle size of the metal particles 17 is originally smaller than the gap between adjacent terminals, so-called short circuit between adjacent terminals that electrically connects adjacent terminals does not occur.

As described above, in the connection method using the heat-seal connector, the film thickness of the electrode to be connected is determined by the relationship between the particle diameter of the conductive material of the heat-seal connector and the film thickness of the electrode to be connected. It should be larger than the particle size of the conductive material of the seal connector.

However, if the film thickness of the electrode to be connected is simply made larger than the particle diameter of the conductive material of the heat seal connector, the adhesive force will be reduced, and good connection cannot be achieved. In order to obtain a good connection state, it is necessary to consider the relationship between the film thickness of the electrode to be connected and the particle size of the conductive material of the heat seal connector.

The heat writing liquid crystal display element has an electrode pitch of 2
The display screen has a size of A5 size, with 50 μm, 500 scanning electrodes and 720 signal electrodes. Since the signal electrode has a structure in which the terminals are drawn out on both sides, the electrode pitch of the connecting terminal portion is 500 μm (definition: 2 / mm), which is relatively small.

However, the scanning electrodes have an electrode pitch of 250 μm (definition: 4 / mm) for passing a current, and the number of connection terminals is 500, which is a severe connection pitch. Further, the specifications required for connection are strict conditions such that the current capacity that can be conducted is 1 A and the contact resistance of the connection portion is 1 Ω or less.

When the optimum relationship between the terminal width of the scanning electrode and the terminal gap was obtained using such a thermowriting liquid crystal display element, the relationship shown in FIG. 10 was obtained. Figure 10
It is a figure which shows the relationship between a terminal gap and a short circuit occurrence frequency when terminal pitch is 250 micrometers. As shown in FIG. 10, it was revealed that when the gap between the terminals was set to 150 μm or more, no short circuit occurred between the adjacent terminals. However, the film thickness of the scanning electrode 6 of this embodiment is 1 μm, the film thickness of the conductor electrode 15 of the FPC 4 is 18 μm, and the film thickness of the polymer film 18 is 30 μm.
m, the particle diameter of the solder particles 17 of the polymer film 18 is 20 μm
Is. The heat and pressure were set to the optimum conditions for the polymer film 18.

From this result, the pitch 250 of the scanning electrodes 6 is
The terminal width is 100 μm and the gap between terminals is 150 μm
μm. The pitch of the conductor electrodes 15 of the FPC 4, the terminal width, and the gap between the terminals were the same as those of the scanning electrodes 6.

The film thickness of the conductor electrode 15 of the FPC 4 is 18 μm.
It was decided to be based on the constraint that 500 electrodes should be formed with a definition of 4 electrodes / mm. It has also been revealed that as the electrode becomes finer, a good electrode cannot be formed unless the film thickness of the conductor electrode 15 of the FPC 4 is reduced.

FIG. 11 is a diagram showing the relationship between the film thickness of the terminal electrode and the terminal contact resistance. From the results shown in FIG. 10, with the electrode configuration having a terminal width of 100 μm and a terminal gap of 150 μm,
The relationship of the contact resistance when the film thickness of the conductor electrode 15 of the FPC 4 was changed to 18 μm and the film thickness of the electrode of the terminal portion of the scanning electrode 6 was changed was examined. From the characteristics of FIG. 11, the scanning electrode 6
It was found that the contact resistance was decreased by increasing the film thickness of the terminal portion. Since an aluminum electrode is used as the scanning electrode 6, it is considered that if the terminal portion has a small film thickness, the aluminum electrode is oxidized when the connection is made by applying heat and pressure, and the contact resistance rapidly increases. To be

From this result, the conductor film thickness of the FPC is 18 μm.
Since the thickness is m, the film thickness of the terminal portion of the scan electrode 6 is 1.4.
It was clarified that the contact resistance becomes smaller at μm or more. That is, the film thickness of the conductor 15 of the FPC 4 and the scanning electrode 6
In the region where the thickness including the film thickness of the terminal portion of 1) is 19.4 μm or more, the contact resistance of 1Ω or less as the target specification could be satisfied.

FIG. 12 is a diagram showing the relationship between the film thickness of the terminal portion of the scanning electrode 6 and the adhesive strength of the connecting portion. In the figure, it was found that the adhesive strength was the largest when the film thickness of the terminal portion was in the range of 1.4 μm to 2.5 μm.

FIG. 13 is a diagram showing the relationship between the film thickness of the terminal portion of the scanning electrode 6 and the film thickness of the conductor electrode 15 of the FPC 4, the contact resistance and the adhesive strength. As a method of connecting the terminal portions, both characteristics of contact resistance and adhesive strength must be satisfied at the same time. From the results of FIG. 11 and FIG. 12, the specifications of the connection portion in the thermal writing liquid crystal display device in which a relatively large current is applied become strict as the contact resistance is 1 Ω or less and the adhesive strength is 500 g / cm ² or more. The range of the portion A can satisfy the specifications, and the film thickness dt of the terminal portion at that time is in the range of 1.4 μm to 2.5 μm.

When the heat seal connector method is applied to a display device having a definition of 4 lines / mm or more and a large current is passed through a large screen, the particle size of the metal particles 17 used for the heat seal connector is , About 20 μm is close to the minimum grain size in terms of manufacturing technology, and the thickness dc of the conductor 15 of the FPC 4 is
Since the maximum thickness is about 18 μm due to the restriction on the conductor formation of the FPC 4, the total film thickness of the thickness dc of the conductor 15 and the film thickness dt of the terminal portion is 18 μm, and the total film thickness is 1.4 to 2.5 μm.
The optimum value is dc + dt = 19.4 to 20.5 μm, and the relationship with the particle diameter d _M of the metal particles 17 is expressed by the following equation.

0.97d _M ≤ dc + dt ≤ 1.025d _{M In} the special case where a relatively large current is applied to the connection, the relation expressed by the above equation should be satisfied, but in general, the electric field In effect type liquid crystal displays, fluorescent displays, electroluminescence displays, plasma displays, etc.,
Do not apply high current to the connection. Therefore, it is not necessary to apply a large current unlike the thermal writing liquid crystal display device, so that there is no problem if the contact resistance is about 100Ω or less.
In addition, since the adhesive strength is low in heat generation at the terminals,
If it is 00 g / cm ² or more, there is no practical problem.

From this, when it is applied to a general flat panel display device, it can be used within the range of the portion B shown in FIG. 13, and the film thickness dt of the terminal portion of the scanning electrode 6 at that time. , Dt = 0.5 to 2.8 μm, and F
The thickness d of the conductor electrode 15 of PC4 added with dc = 18 μm
The optimum range is c + dt = 18.5 to 20.8 μm. Therefore, the relationship with the particle diameter d _M of the metal particles of the heat seal connector is expressed by the following equation.

0.925d _M ≦ dc + dt ≦ 1.04d _M As described above, when the definition is 4 lines / mm or less and a large current is passed with a large capacity, the film of the terminal portion of the scanning electrode 6 is formed. The relationship between the thickness dt and the thickness dc of the conductor electrode 15 of the FPC 4 is dc + dt = 19.4 to 20.5 μm. In the present embodiment, dc = 18.0 μm was set, but when the value of dc is changed, naturally, dc + dt = 19.4 to 2
The film thickness dt of the terminal portion may be changed so as to be in the range of 0.5 μm.

[0057] In the case of the display device is not necessary to flow a large current, selecting 400 g / cm ² or more as a practical range of the bonding strength, from 13, the relationship _{0.905d M ≦ dc + dt ≦ 1.04d} M Is obtained.

FIG. 14 is a diagram showing the relationship between the terminal width, the maximum energizing current, and the frequency of occurrence of short circuits. Needless to say, when the film thickness of the terminal portion is changed, the terminal portion film thickness dt is changed so as to be within the optimum value range when applied to a general display device.

The characteristics shown in FIG. 14 can be obtained by rewriting the relationship between the terminal pitch Lp of the terminals of the display element shown in FIG. 10 and the inter-terminal gap Lg into the relationship between the terminal width and the location where the short circuit occurs. FIG. 14 shows the relationship between the terminal width when the terminal portion film thickness is 5000 Å and the maximum energizing current when the pulse width is 10 ms.

From FIG. 14, the terminal width Lp of the thermal writing liquid crystal display device which conducts a relatively large current has a specification for the energizing current value of 1 A or more and does not cause a short circuit between adjacent terminals.
Is only in the shaded area, and Lp = 100 to 125 μ
The range is m. Therefore, the optimum range of the inter-terminal gap is Lg = 125 to 150 μm, and the optimum relationship between the terminal pitch Lp at the end and the inter-terminal gap Lg is expressed by the following equation.

0.5Lp ≦ Lg ≦ 0.6Lp The film thickness dt of the terminal portion of the scanning electrode 6, the thickness dc of the conductor electrode 15 of the FPC 4 and the particle diameter d _{M of the} metal particles dispersed in the heat seal connector. The relationship between the terminal pitch Lp and the inter-terminal gap Lg has been described. However, when the present embodiment is applied to a display device or a connection in which a larger current flows, the film thickness dt of the terminal portion of the scanning electrode 6 is increased. do it.

When the inter-terminal gap Lg is smaller than the above range, a short circuit occurs between the adjacent terminals. However, when a pulse current is applied to the short circuit portion, the short circuit occurs without damaging the terminal portion. We have established a method that can melt down only the part and eliminate the short circuit condition. If used together with this short circuit correction method, it can be used even if it is slightly deviated from the optimum relationship between the terminal gap Lg and the terminal pitch Lp. it can.

The heat and pressure applied to the heat seal connector using the polymer film 18 in this embodiment was not described in detail. The optimum value for heat is determined from the characteristics of the adhesive 16 used for the polymer film 18, and the optimum value for pressure is determined from the terminal pitch, the terminal width, and the film thickness of the polymer film.

Further, from the results of this example, in the connection method in which heat and pressure are applied to the polymer film to connect, when the relatively large current is applied to the connection portion, the resistance is smaller than the specific resistance of the metal particles of the polymer film. It became clear that it is an important condition to select a terminal electrode material having a specific resistance or sheet resistance.

FIG. 15 is a micrograph showing the state of metal particles in the connection structure of the flat panel display device connected according to the present invention. It is understood from FIG. 15 that the solder particles 17 on the scanning electrodes 6 are crushed and spread well, and the contact area between the scanning electrodes 6 and the electrodes 15 is expanded.

On the other hand, the solder particles 17 in the gaps other than between the scanning electrodes 6 and 15 are not crushed and maintain the substantially original particle diameter, and the adjacent scanning electrodes 6 are electrically connected. At first glance, it is clear that no so-called short circuit between the connected scan electrodes occurs.

In this way, the scan electrodes 6 to be connected are
When the thickness of the electrode 15 and the thickness of the electrode 15 is equal to or larger than the particle diameter of the solder particles 17, the adhesive strength is not reduced, the contact resistance is small, and a relatively large current is applied. It became clear that it could be done.

By the way, when the gap between the terminals is reduced, a short circuit state occurs, but the inventors have also established a method of eliminating the short circuit state by causing a pulsed current to flow therethrough. .

In the above embodiments, the connection structure between the scanning electrodes on the display element side and the conductor electrodes on the printed board side has been described. However, the present invention is applied to the signal electrodes on the display element side and the conductors on the printed board side. It will be apparent that it can also be applied to a connection structure with electrodes.

[0070]

According to the present invention, a flat panel display having means for easily connecting terminals of a flat panel and terminals of a circuit for supplying a signal to the flat panel without causing displacement or contact failure. The device is obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic structure of a liquid crystal display device to be connected according to the present invention together with a polymer film according to the present invention.

FIG. 2 is a diagram showing a state of terminals and electrodes connected by a polymer film of the present invention.

3 is a perspective view showing a state before connection of the electrodes of FIG. 2. FIG.

FIG. 4 is a micrograph showing a dispersion state of metal particles in a polymer film as an anisotropic conductive film according to the present invention.

FIG. 5 is a diagram schematically showing a connection method using a polymer film according to the present invention.

FIG. 6 is a diagram showing a state before connection of a defect example in which the particle diameter of the metal particles of the polymer film is larger than the sum of the thickness of the scanning electrode and the thickness of the conductor electrode of the FPC.

FIG. 7 is a diagram showing a state after connection of the defect example of FIG. 6;

FIG. 8 is a diagram showing a state before connection of a suitable example in which the particle size of metal particles of a polymer film is smaller than the thickness of the scanning electrode and the conductor electrode of the FPC.

FIG. 9 is a diagram showing a state after connection of the preferred example of FIG.

FIG. 10 is a diagram showing the relationship between the terminal gap and the frequency of occurrence of short circuits when the terminal pitch is 250 μm.

FIG. 11 is a diagram showing a relationship between a film thickness of a terminal electrode and a terminal contact resistance.

FIG. 12 is a diagram showing a relationship between a film thickness of a terminal electrode and an adhesive strength of a connecting portion.

FIG. 13 is a graph showing the relationship between the film thickness of a terminal electrode and the film thickness of an FPC conductor, and contact resistance and adhesive strength.

FIG. 14 is a diagram showing a relationship between a terminal width, a maximum energizing current, and a short circuit occurrence frequency.

FIG. 15 is a micrograph showing a state of metal particles in a connection structure of a flat panel display device connected according to the present invention.

[Explanation of symbols]

 1 Polymer Film 2 Molten Metal 3 Liquid Crystal Display Element 4 Flexible Printed Circuit Board (FPC) 6 Scanning Electrode 7 Signal Electrode 8 Liquid Crystal 9 Alignment Film 10 Scanning Electrode Substrate 11 Signal Electrode Substrate 12 Sealant 13 Supporting Material 14 Base Film 15 Electrode 16 Adhesion Agent 17 Metal particles 18 Polymer film 19 Rigid substrate 20 Circuit conductor

Claims (2)

[Claims] 1. A flat panel display element having a plurality of scanning electrodes and a plurality of signal electrodes for displaying image information according to an electric signal applied to the scanning electrodes and the signal electrodes; A flexible printed board having a conductor to be connected to a terminal portion for supplying an electric signal to a scanning electrode or a signal electrode; a particle diameter d _{M of the} metal particle including a synthetic resin adhesive and metal particles and a terminal of the display element The film thickness dt of the part and the film thickness dc of the conductor to be connected are formed so as to have the following equation, and the conductivity has directionality, and the terminal part of the scan electrode or the signal electrode and the conductor to be connected A flat panel display device comprising: a polymer film sandwiched between and to which heat and pressure are applied to connect the terminal portion to the conductor; and 0.905 d _M ≤dt + dc ≤1.04 d _M. 2. The flat panel display device according to claim 1, wherein the terminal pitch Lp of the terminal portion of the display element and the inter-terminal gap Lq are formed so as to satisfy the following equation. Panel display device. 0.5Lp ≦ Lg ≦ 0.6Lp