JPH08255958A - Flexible board, and structure and method for its connection - Google Patents

Abstract

PURPOSE: To obtain a flexible board in which the state of a pressurization can be grasped visually and in which a connection state is controlled easily by a method wherein at least two kinds of coloring members are used in an adhesive conductive member. CONSTITUTION: When a flexible board and an LCD panel are connected, conductive elements 7 as will as first pigment balls 1' and second pigment balls 1" are scattered in an adhesive conductive member 10 for a heat seal. The strength of the conductive elements is sufficient as compared with that of the pigment balls, and the continuity elements are not destroyed by a pressurization operation when the heat seal is connected. The diameter of the pigment balls 1' is a little larger than, or equal to, the size of a desired gap 6, and every first pigment is sealed inside a ball shell. On the other hand, the second pigment balls 1" are pigment balls whose diameter is smaller than the size of the desired gap 6, and every second pigment is sealed inside a ball shell. When a pressurization in their connection is proper and the gap 6 is a desired size, only the pigment balls 1' which are larger are destroyed, and the adhesive conductive member looks like the color of the first pigment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible substrate, a connecting structure therefor, and a connecting method therefor, and is particularly suitable for a flexible substrate connected to a liquid crystal display device.

[0002]

2. Description of the Related Art The structure of a flexible substrate will be described below by taking a connection structure between a flexible substrate and a liquid crystal display element (hereinafter referred to as an LCD panel) as an example.

FIG. 3 shows a conventional flexible substrate connection structure, 4 is a flexible tape, which is made of a flexible base material (thickness of about 30 μm) made of a resin such as polyester, and 8 is conductive of the flexible tape. It is a pattern and is formed by printing fine particles of silver or graphite. Reference numeral 5 is an LCD panel made of glass or the like, and 9 is a transparent electrode of the LCD panel, which is formed on the surface of the LCD panel by an ITO film or the like (several microns in thickness). Reference numeral 10 denotes an adhesive conductive member, and conductive elements 7 (hereinafter referred to as resin balls) are scattered on the adhesive conductive member. Resin ball 7 has a diameter of 10
About micron, solid is made of resin and metal such as gold is plated on the surface. The conductive pattern 8 of the flexible tape and the transparent electrode 9 of the LCD panel are adhered by the adhesive conductive member, and the resin balls are scattered to establish the conduction. Generally, the structure of the flexible substrate exists in a state where the adhesive conductive member 10 is applied to the conductive pattern of the flexible substrate. In particular, the flexible substrate with the adhesive conductive member applied is called a heat seal connector.

Next, a method of connecting a heat seal connector (hereinafter referred to as heat seal), that is, heat seal and LCD
The method of connecting the electrodes to the panel will be described. The heat-sealing connection is one of the methods of collectively connecting a large number of electrodes having, for example, about 200 terminals, and is mainly used for obtaining conduction between an LCD panel and a driver IC that drives the LCD panel. For heat seal connection, the transparent electrode 9 on the LCD panel 5 is brought into contact with the adhesive surface of the heat seal 4 and heated from above using a pressure bonding jig (hard rubber or the like, not shown) heated to, for example, 200 ° C. When pressure is applied, the adhesive conductive member 10 is melted by heat, and is removed in the depth direction of the drawing by the pressure so that the resin ball 7 comes into contact with the transparent electrode 9 of the LCD panel 5. Here, when the crimping jig is removed and heating and pressurization are stopped, the adhesive conductive member 10 is cooled and hardened so that the resin ball 7 becomes the LCD panel 5.
This is a connection method for ensuring electrical continuity by holding the pressed state between the transparent electrode 9 and the conductive pattern 8 of the heat seal 4. At this time, the gap 6 is filled with the adhesive conductive member 10, and the size thereof is ideally smaller than the diameter of the resin ball 7.

In the heat-sealing connection, a large number (for example, 200) of terminals as shown in the figure are arranged in a row in the lateral direction, and it is important that the terminals are simultaneously connected by appropriate and uniform pressure.

[0006]

However, if the applied pressure is weak, the contact pressure between the resin ball 7 and each conductive pattern 8 and the transparent electrode 9 becomes insufficient, so that electrical continuity cannot be obtained or the connection reliability is insufficient. There were cases where it became a connection. Especially in the conventional flexible board connecting method, there may be a deviation in the parallelism between the surface of the crimping jig and the connecting surface, or the pressing force may become uneven due to one-sided slippage due to wear of the crimping jig, Partially poor connection was sometimes obtained. However, in the conventional flexible substrate structure and the connection structure using the same, it is not possible to easily determine the connection quality.

Further, a pressure measuring sheet called pressure sensitive paper has been used for measuring the pressure applied to the connection of the conventional flexible substrate. This pressure-sensitive paper is a set of two pressure measuring sheets in which one sheet is coated with a coloring reagent and the other sheet is coated with a reactive agent. In the large area, the two sheets are strongly compressed so that a color reaction occurs and a color appears, and in the small area the color does not develop so that the pressure distribution can be confirmed and measured by color. Since the use of pressure-sensitive paper causes a sheet (that is, a foreign substance) to intervene on the pressing surface, it was necessary to stop the process for measuring the pressing force. In other words, although the absolute value and distribution of the pressing force are very important factors in the connection of flexible boards, foreign matter must be present on the joint surface in order to measure and manage them, so the processing step The pressure could not be measured easily.

Therefore, the present invention solves such a problem, and an object of the present invention is to provide a flexible substrate connection structure and its connection that can easily determine that the flexible substrates have been securely connected. To provide a method.

It is another object of the present invention to provide a flexible board connection structure and a connection method thereof, in which the connection inspection can be performed easily.

[0010]

[Means for Solving the Problems]

(Means 1) A flexible substrate having a flexible base material, a conductive pattern provided on the base material, and an adhesive conductive member covered with the conductive pattern, wherein the adhesive conductive member is , A conductive element capable of electrical conduction, and a coloring member that develops a color when pressed.

(Means 2) In addition to the characteristics of the means 1, the flexible substrate is characterized in that the coloring members scattered on the adhesive conductive member have at least two kinds of coloring members.

(Means 3) In addition to the characteristics of the means 2, the flexible substrate further includes a first coloring member in which the coloring members scattered on the adhesive conductive member have a diameter larger than that of the conductive element. And a second coloring member having a diameter smaller than that of the conducting element.

(Means 4) Further, the connection structure of the flexible substrate has a flexible substrate having a conductive pattern, a liquid crystal display element having a transparent electrode, and a coloring member that develops color by an external pressure, and the conductive pattern and the transparent electrode. And an adhesive conductive member that is interposed between the transparent electrode and the conductive pattern of the flexible substrate to connect the conductive pattern with an electrically conductive element, and the transparent electrode and the conductive pattern of the flexible substrate are colored members. Are connected by the adhesive conductive member in the colored state.

(Means 5) In addition to the characteristics of the means 4, the flexible substrate connection structure is characterized in that an uncolored coloring member is present in the adhesive conductive member.

(Means 6) Further, the flexible substrate connection structure has a flexible substrate having a conductive pattern, a liquid crystal display element having a transparent electrode, and a coloring member that develops color by an external pressure, and the conductive pattern and the transparent electrode. An adhesive conductive member that is interposed between the transparent electrode and the conductive pattern of the flexible substrate and is connected by a conductive element capable of electrical conduction, and the coloring member is the adhesive conductive member in a non-colored state. The transparent electrode and the conductive pattern of the flexible substrate are connected to each other.

(Means 7) Further, the method of connecting the flexible substrate is such that the conductive pattern of the flexible substrate and the transparent electrode of the liquid crystal display element are connected by an adhesive conductive member containing a conductive element capable of electrically conducting. In the connection method, the adhesive conductive member includes a coloring member that develops a color when pressed, and a state of the coloring member indicates a connection state between the conductive pattern and the transparent electrode.

[0017]

Therefore, according to the flexible substrate described in the means 1, since the flexible substrate has the coloring member that develops color by pressurization, if the proper pressurization is applied, it can be easily connected depending on the state of the coloring member. Can judge.

In addition to this, according to the flexible substrate described in the means 2, it becomes easy to grasp the state of the pressing force by using at least two kinds of coloring members. Also, the control of the connection state becomes easy.

Further, according to the flexible substrate described in the means 3, the color-developing member having a diameter at least larger than the diameter of the conductive element is colored when the conductive is surely established. Therefore, depending on the state of the color-developing member, it is easy to determine whether the state is the optimum pressurization state or the optimum connection state.

According to the flexible substrate connection structure according to any one of the means 4 to 6, it is possible to judge whether the connection is good or bad depending on the state of the adhesive conductive member, and moreover, it is possible to visually check without using a special device. It is also possible to judge by.

According to the flexible board connecting method described in the means 7, it is possible to judge the quality of the connection based on the coloring state of the adhesive conductive member.

[0022]

EXAMPLE FIG. 1 shows an example of a coloring member dispersed in the adhesive conductive member used in the present invention. In this embodiment, a case where the outer shape is a sphere will be described as an example. FIG. 1A shows a coloring member 1 made of a sphere, and a spherical shell 2 is made of a material that is hard and easily broken, such as a resin, and a pigment 3 is encapsulated therein in a state where it easily diffuses. The hard and fragile material is, for example, a hard plastic such as polycarbonate, which is a material that is destroyed without being deformed by a pressure applied when a flexible substrate (hereinafter referred to as heat seal) is connected. In addition, the state of being easily divergent means a state of diverging without a container such as gas, liquid or powder. The coloring member 1 (hereinafter referred to as a dye sphere) releases the material of the liquid spherical shell 2 into a spherical shape in a liquid curing agent, injects the dye 3 as the content into the inside, and then hardens the spherical shell. It can be formed. By defining the amount of each material at this time, the diameter of the pigment sphere and the thickness of the spherical shell 2 can be controlled to desired dimensions. In this example, a spherical body is described as an example, but any shape may be used as long as the dye 3 is encapsulated.

FIG. 1B shows a state before the heat seal and the LCD panel are connected to each other, showing an embodiment of the heat seal structure of the present invention. 5 is L made of glass or the like
CD panel, 9 is a transparent electrode of LCD panel, LC
An ITO film or the like (thickness of several microns) is formed on the surface of the D panel. 4 is a flexible tape, which is made of a flexible base material (thickness: about 30 microns) made of a resin such as polyester. 8 is a conductive pattern of a flexible tape, which is formed by printing fine particles such as silver or graphite. Reference numeral 10 denotes an adhesive conductive member, on which conductive elements 7 (hereinafter referred to as resin balls) and first and second dye spheres 1 ′ and 1 ″ which are coloring members are scattered. The ball has a diameter of about 10 microns, the solid is a resin sphere, and the surface is plated with metal such as gold.The resin ball has sufficient strength compared to the dye sphere described later, and pressure etc. at the time of heat seal connection It has such a strength that it will not be destroyed by the external pressure of 1. The dye spheres 1 of this embodiment have different diameters of two kinds of dyes. 1'is slightly larger than or equal to the desired 6 dimensions. A pigment sphere having a diameter, which is generally slightly larger than or equal to the diameter of the conducting element, and the first pigment (for example, yellow) is enclosed in the spherical shell 2. There is.
On the other hand, 1 ″ is a pigment sphere having a diameter smaller than the desired size of 6 dimensions, and generally has a diameter smaller than that of the conducting element, and the second pigment (for example, red) is contained in the spherical shell 2. Further, the above-mentioned desired clearance 6 dimension is a dimension slightly smaller than the diameter of the resin ball 7, and when the distance between each conductive pattern 8 and the transparent electrode 9 is in this range, good heat sealing is achieved. The heat-sealing structure exists in a state where the conductive pattern 8 of the flexible tape 4 is coated with the adhesive conductive member 10 containing resin balls and pigment balls. In the example, the conductive pattern 1 of the flexible tape 4
An example in which the adhesive conductive member 10 is applied to one of the two is shown, but it is preferable to apply the adhesive conductive member 10 to all of the conductive patterns that are continuously arranged from the viewpoint of simplification of application.

Next, an LCD using the heat seal of this structure
A method for connecting to a panel, that is, a method for connecting a heat-seal conductive pattern and a transparent electrode to an LCD panel will be described. The heat seal connection is one of the methods of collectively connecting a large number of electrodes, for example, about 200 terminals.
It is used to obtain conduction between the CD panel and the driver IC that drives the CD panel. Heat seal connection is LC
The adhesive surface of the heat seal 4 is brought into contact with the transparent electrode 9 on the D panel 5, and pressure and heat are applied from above with a pressure bonding jig (hard rubber or the like, not shown) heated to, for example, 200 ° C. The agent layer 10 is melted by heat and is removed by pressure in the depth direction of the drawing, so that the resin ball 7 comes into contact with the transparent electrode 9 of the LCD panel 5. When the pressure-bonding jig was removed and heating and pressurization were stopped, the adhesive layer 10 was cooled and hardened, and the resin ball 7 was pressed between the transparent electrode 9 of the LCD panel 5 and the conductive pattern 8 of the heat seal 4. This is a connection method for maintaining electrical continuity by maintaining the state. At this time, the gap 6 is filled with the adhesive 10, and its size is ideally slightly smaller than the diameter of the resin ball 7.

In the heat-sealing connection, a large number (for example, 200) of terminals as shown in the figure are continuously arranged in the lateral direction, and it is important that the terminals are simultaneously connected by appropriate and uniform pressure.

When the above-described connection structure and method are used here, since the conductive elements 7 are scattered in the adhesive conductive member 10, a pressure bonding jig (not shown) and The heat seal 4 is bent, and the gap 6 between each conductive pattern 8 and the transparent electrode 9 may be appropriate or inappropriate depending on the magnitude of the pressing force, resulting in the following state. FIG. 2 shows an explanatory diagram thereof.

(1) When the gap is appropriate FIG. 2A shows an embodiment of the present invention when the gap is appropriate. When the pressing force is appropriate and the gap 6 between the LCD panel 5 and the heat seal 4 (that is, the thickness of the adhesive layer 10) has a desired size, only the larger dye sphere 1'is destroyed and the yellow dye is removed. Since the particles are scattered, the adhesive conductive member 10 looks yellow.

(2) Inappropriate gap The inadequate gap occurs when the pressure is insufficient or excessive. FIG. 2B shows an explanatory view when the applied pressure is insufficient. In this case, the gap 6 '
Is greater than or equal to the diameter of the dye sphere 1 ′, the dye sphere 1 ′ is not destroyed, and therefore the color of the adhesive conductive member 10 does not change.

On the other hand, FIG. 2 (c) shows an explanatory view when the applied pressure is excessive. In this case, since the pressing force is excessive, the crimping jig and the heat seal 4 are bent and have a shape following the resin ball 7 which is hard to break. At this time, since the gap 6 "is smaller than the diameter of the dye sphere 1", the dye spheres 1'and 1 "are destroyed and the yellow and red dyes are scattered, respectively. Therefore, the adhesive conductive member 10 is yellow and red. It looks like a mixed color (around orange).

Therefore, by observing the color of the adhesive conductive member 10, it is possible to know whether the gap between the LCD panel 5 and the heat seal 4 is within a certain range, and as a result, whether the pressure applied in the heat seal connection is appropriate. I can know how.

Although the above description has explained dye spheres in which a dye is enclosed, the contents are not limited to dyes, and dye spheres in which a chromogenic reagent is encapsulated are contained in an adhesive layer containing a reaction agent. It may be used in conversely or vice versa.
At this time, since the presence or absence of color becomes clearer, it is more effective to confirm the applied pressure by color.

Further, although the above description has explained the case of using two types of dye spheres, the type of dye sphere is not limited to this. It is also possible to compare the magnitude of the pressing force by using one type of dye sphere, and if a heat seal using multiple types of dye spheres is used after calibrating the relationship between color and pressure in advance, it will be more precise. Connection is possible.

In addition, the embodiment of the present invention can be applied to the conventionally used heat seal to judge whether the connection is good or not at the same time as the use of the heat seal. It can be removed, and inspection can be done easily. Further, since no foreign matter is present on the joint surface, there is no need to remove it later, and it can be used at all times without stopping the work during the process.

[0034]

Since the present invention is constructed as described above, it has the following effects.

According to the flexible substrate of the means 1, since the flexible substrate has a coloring member that develops color by applying pressure, it is possible to easily determine whether or not the connection is surely made, depending on the state of the coloring member, if proper pressure is applied. it can. Therefore, the quality and connection reliability of the heat seal connection are improved.

In addition to this, according to the flexible substrate described in the means 2, by using at least two kinds of coloring members, it becomes easy to grasp the state of the pressing force. Also, the control of the connection state becomes easy.

Further, according to the flexible substrate described in the means 3, the first coloring member whose coloring member has a diameter larger than the diameter of the conducting element and the second coloring member having a diameter smaller than that of the conducting element. Therefore, if the conduction is surely established, at least the coloring member having a diameter larger than the diameter of the conducting element will be colored, and the state of the coloring member is in the state of the optimum pressurization or the state of the optimum connection. It will be easier to determine if there is one.

According to the flexible board connection structure according to any one of the means 4 to 6, it is possible to judge whether the connection is good or bad depending on the state of the adhesive conductive member, and moreover, it is possible to visually check without using a special device. It is also possible to judge whether the connection state is good or bad.

According to the flexible board connecting method described in the means 7, it is possible to judge the quality of the connection based on the coloring state of the adhesive conductive member.

Further, by adopting the constitution of the present invention, the state of pressure (absolute value, distribution, etc.) can be confirmed and measured easily and surely.

Further, since the pressure measuring surface can be used in the same manner as the conventional heat sealing without interposing any foreign matter, it is not necessary to remove the pressure measuring sheet,
Constant pressure measurement (in-process) is possible in the heat seal crimping process. Therefore, in the heat seal connection process, the connection and the pressure measurement can be performed at the same time, and the processing man-hour and the processing time can be rationalized. Therefore, it is possible to improve reliability in an electronic device (for example, a portable personal computer or the like) using the heat seal connection and to reduce the cost.

Further, according to the present invention, regarding the heat seal connection, the absolute value and distribution of the pressing force, which is an important factor for determining the connection reliability, can be easily and surely grasped by checking the color of the connection portion. . Further, it is possible to manage the non-uniformity of the pressing force due to various factors in the mass production process, that is, in-process (that is, in-process without stopping the process for measurement).

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of a coloring member of the present invention.
FIG. 1A is a side view and a sectional view showing the structure of the color forming member of the present invention. FIG. 1B is a cross-sectional view in which a heat seal using the coloring member of the present invention is connected.

FIG. 2 is a cross-sectional view showing an example of a connected state of a heat seal using the coloring member of the present invention. FIG. 2A is a cross-sectional view of the case where the heat seal of the present invention is used and the connection is performed at an appropriate pressure. FIG. 2 (b) is a cross-sectional view of the case where the heat seal of the present invention is used for connection with an excessive pressure. FIG. 2C is a cross-sectional view of the case where the heat seal of the present invention is used for connection with excessive pressure.

FIG. 3 is a cross-sectional view showing a case where connection is performed using a conventional heat seal.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Coloring member 1 ', 1 "... Dye sphere 2 ... Spherical shell 3 ... Dye 4 ... Flexible tape 5 ... LCD panel 6 ... Gap 7 ... Resin ball 8 ... Heat seal conductive pattern 9 ... LCD panel transparent electrode 10. Adhesive conductive member

Claims (7)

[Claims] 1. A flexible substrate having a flexible base material, a conductive pattern provided on the base material, and an adhesive conductive member covered with the conductive pattern, wherein the adhesive conductive member is a flexible substrate. Is a conductive element capable of electrical conduction,
A flexible substrate having a coloring member that develops color when pressed. 2. The flexible substrate according to claim 1, wherein the coloring member scattered on the adhesive conductive member has at least two kinds of coloring members. 3. The color-developing members scattered on the adhesive conductive member include a first color-developing member having a diameter larger than the diameter of the conductive element and a second color-developing member having a diameter smaller than the diameter of the conductive element. The flexible substrate according to claim 2, wherein the flexible substrate is formed of 4. A flexible substrate having a conductive pattern, a liquid crystal display element having a transparent electrode, and a coloring member that develops color by an external pressure. The transparent substrate is interposed between the conductive pattern and the transparent electrode. An adhesive conductive member that connects a conductive pattern of a flexible substrate with a conductive element capable of electrical conduction, wherein the transparent electrode and the conductive pattern of the flexible substrate are in a colored state of a coloring member. A flexible substrate connection structure characterized by being connected by means of. 5. The connection structure using a flexible substrate according to claim 4, wherein an uncolored coloring member is present in the adhesive conductive member. 6. A flexible substrate having a conductive pattern, a liquid crystal display element having a transparent electrode, and a coloring member that develops color by an external pressure. The transparent substrate is interposed between the conductive pattern and the transparent electrode. The transparent conductive electrode and the conductive pattern of the flexible substrate are composed of an adhesive conductive member that connects the conductive pattern of the flexible substrate with a conductive element capable of electrically conducting, and the coloring conductive member is the adhesive conductive member in the uncolored state. A flexible substrate connection structure characterized by being connected to each other. 7. A method of connecting a flexible substrate, wherein the conductive pattern of the flexible substrate and the transparent electrode of the liquid crystal display element are connected by an adhesive conductive member containing a conductive element capable of electrically conducting. The method for connecting a flexible substrate according to claim 1, wherein the flexible substrate includes a color-developing member that develops color when pressed, and a state of the color-developing member indicates a connection state between the conductive pattern and the transparent electrode.