JPH06291458A - Circuit mounting method of board - Google Patents

Abstract

PURPOSE:To provide the circuit mounting method of a board which can reduce a bad influence due to heat on the board as much as possible and in which the reliability of an electrical connection can be increased. CONSTITUTION:In a method in which a circuit is mounted along a board on which an electrode pattern having comb tooth-shaped peripheral-edge electrodes has been formed, a circuit pattern having comb tooth-shaped connecting electrodes whose pitch interval is the same as that of the comb tooth-shaped electrodes 23 on the board is formed on a slender sheetlike glass board 11 along the transverse direction or the longitudinal direction around the board. The method is provided with a process in which bumps 15 are formed respectively in the comb tooth-shaped electrodes 12 of the circuit pattern, with a process in which the required number of circuits 16 is mounted directly on the circuit pattern, with a process in which the comb tooth-shaped electrodes 23 on the board are brought into contact with the corresponding bumbs 15 on the glass board 11 and in which the bumps 15 are irradiated with heat radiation and melted and with a process in which the board and the glass board 11 are fixed by an adhesive after the processes.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of mounting a drive circuit or the like on a substrate used for various flat displays, liquid crystal sensors, liquid crystal shutters and the like.

[0002]

2. Description of the Related Art Conventionally, liquid crystal displays have been used as various display devices.
Flat panel displays such as plasma display, electroluminescence (EL) display, and light emitting diode (LED) display are known. In these display panels, transparent electrodes, which form a large number of display dots (pixels) arranged in a matrix on a transparent glass substrate, are usually formed with high precision, and a comb-like shape is formed around the substrate. A drive circuit or the like is connected to the electrodes.

In recent years, as a method of mounting a drive circuit or the like on a display substrate of a display panel, for example, a semiconductor integrated with a tape obtained by laminating copper on a film carrier made of a material such as polyimide or polyester and patterning electrodes. A TAB (Tape Automated Bonding) method in which a driving element (chip) such as a circuit (IC) is bonded and connected to an electrode portion on the periphery of the display substrate by soldering or thermocompression bonding, or a bare circuit element (bare chip) is used. A COG (Chip On Glass) system or the like, which is directly mounted on the peripheral edge of the display substrate, is used.

However, in the TAB method, since a resin film such as polyimide or polyester is used for the tape, a difference in the coefficient of thermal expansion between the tape and the display substrate causes a difference in the Pucci interval in a large area. The connection becomes difficult, and a malfunction occurs after the connection, so that the pitch is about 100 μm. Further, in the COG method, since the elements are directly mounted on the display glass substrate, it becomes difficult to inspect, replace or repair (repair) the defective integrated circuit, and the display glass substrate side depending on the design of the integrated circuit. Since it is necessary to change the circuit pattern in various ways, a defect of a part of a glass substrate having a large area becomes a defect of the whole, resulting in poor yield, high cost, and difficulty in commercialization.

In contrast, US Pat. No. 5,084,96
In No. 1, a circuit pattern having comb-shaped connecting electrodes with the same pitch interval as the comb-shaped peripheral electrodes of the substrate was formed on an elongated glass substrate having the same coefficient of thermal expansion as the substrate, and the necessary circuits were mounted directly. After that, an anisotropic conductive adhesive containing metal particles and the like is applied between the comb-teeth electrode of the substrate and the corresponding comb-teeth electrode of the circuit board, and pressure bonding and heat treatment are performed to electrically connect the two. A technique related to a circuit mounting method of a substrate to be connected is disclosed.

[0006]

However, in the circuit mounting method using the elongated glass substrate on which the circuit pattern having the comb-teeth-shaped connection electrodes is formed, heating for a long time is required to connect the corresponding electrodes on the substrate and the glass substrate. Since the treatment is required, there is a drawback that the substrate is adversely affected. Further, in the method of connecting electrodes using an anisotropic conductive adhesive, a large number of electrodes are electrically connected at the same time by pressure-bonding metal particles, which may cause connection failure.

[0007] Therefore, an object of the present invention is to provide a circuit mounting method for a substrate which can minimize adverse effects of heat on the substrate and can improve reliability of electrical connection.

[0008]

In order to achieve the above object, a circuit mounting method for a substrate of the present invention is a method for mounting a circuit around a substrate on which an electrode pattern having a comb-shaped peripheral electrode is formed. On the elongated plate-shaped glass substrate along the lateral direction or the sub-direction around the substrate, a circuit pattern having comb-teeth connection electrodes having the same pitch interval as the comb-teeth peripheral electrode of the substrate is formed, and the circuit pattern of the circuit pattern is formed. Steps of forming bumps on the comb-teeth connecting electrodes, directly mounting a required number of circuits on the circuit pattern, and bringing the comb-teeth peripheral electrodes of the substrate into contact with corresponding bumps of the glass substrate. And a step of irradiating the bumps with a heat ray to melt the bumps, and a step of fixing the substrate and the glass substrate with an adhesive after the step.

[0009]

According to the present invention, bumps are formed on the comb-teeth connecting electrodes of the circuit pattern formed on the glass substrate, and the comb-teeth peripheral electrodes of the substrate are brought into contact with the bumps of the corresponding circuit substrate of the glass substrate. Since the bumps are irradiated with spot-shaped or linear heat rays to be melted, heating is performed in a short time, the adverse effect of heat on the substrate is reduced, and the electrical connection of the electrodes on both substrates is also melted. It will be done because it is done.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to an embodiment shown in the drawings. FIG. 2 is a perspective view of the glass circuit board according to the embodiment of the present invention.

In FIG. 1, a glass circuit board 10 of the embodiment of the present invention is, for example, a board for mounting a drive circuit of a liquid crystal display panel and has the same coefficient of thermal expansion as this liquid crystal display panel. It is formed on the surface of a transparent glass substrate 11 formed in an elongated plate shape (stick shape) having a length approximately equal to the longitudinal or lateral direction of the peripheral edge. That is, a circuit pattern for directly mounting a semiconductor bare chip for driving a liquid crystal is formed on the surface of the glass substrate 11, and is formed on one side of the surface along the longitudinal direction at the periphery of the liquid crystal display panel. The same tooth-shaped output side electrodes 12 are formed at the same pitch as the scanning electrodes and the data electrodes, and the other end side is, for example, a comb tooth-shaped input side connected to a control circuit or the like provided on a printed circuit board. The electrode 13 is formed. The circuit pattern forming such an electrode is made of a transparent conductor and has a thickness of, for example, about 0.2 μm.
TO (indium tin oxide) film, Ni (nickel) film having a thickness of about 1 μm, and thickness of 0.1 to 0.2 μm
It is formed by sequentially stacking Au (gold) films of a certain degree.

FIG. 3 is a perspective view showing a manufacturing process of the glass circuit board of the embodiment of the present invention.

As shown in FIG. 1A, on a glass substrate 30 having a large area having the same coefficient of thermal expansion as that of the liquid crystal panel,
A large number of circuit patterns for the glass circuit board 10 are continuously formed.

Next, as shown in FIG. 2B, the glass substrate 30 is cut into an elongated plate shape (stick shape) to form a plurality of glass circuit boards 10 as shown in FIG.

FIG. 1 is a process diagram showing a circuit mounting method according to an embodiment of the present invention. The parts corresponding to those in FIG. 2 are designated by the same reference numerals.

First, as shown in FIG. 1A, a resin-based insulating film such as polyimide or epoxy is formed on the circuit pattern of the glass circuit board 10 formed as shown in FIG. 2 by a known technique. Etc. or an insulating film 14 of silicon oxide or the like is formed, and through holes are formed in corresponding portions of the mounted semiconductor bare chip for driving liquid crystal, the comb-teeth-shaped output side electrode 12, etc., and the solder dam is formed in the through holes. Thus, the bump 15 for the connection electrode having a projection shape is formed. In the figure, the bumps for connection to the input side electrodes 13 are omitted.

Next, as shown in FIG. 1B, the required number of semiconductor chips 1 for liquid crystal drive circuits are mounted on the glass circuit board 10.
6 is mounted. As the mounting method of this chip 16, for example, the protruding electrode 17 formed on the semiconductor chip 16 is
After contacting the corresponding bumps 15 and heating and bonding, the liquid encapsulant 18 is dropped to encapsulate the semiconductor chips 16. As another mounting method of the semiconductor chip 16, for example, there is a method such as wire bonding.

Next, as shown in FIG. 1C, the side of the glass circuit board 10 on which the semiconductor chip 16 is mounted is turned downward. Then, the upper glass substrate 21 and the lower glass substrate 22
A region for mounting a drive circuit is formed on the lower glass substrate 22 at the periphery of the liquid crystal panel 20 composed of and, and the output electrode 12 of the glass substrate 11 is provided on the end portion of the comb-shaped peripheral electrode 23 of the lower glass substrate 22. Corresponding bump 15 formed on
Are aligned and brought into contact with each other, and then the heat ray 25 is passed from the heat ray generation source 24 through the lower glass substrate 22 to the bump 15
And heat it. Such a heating wire 25 is, for example,
Infrared light or laser light converged in a spot shape or a linear shape is used. In the case of a spot type heat ray, the bumps 15 in the longitudinal direction are scanned so as to be sequentially irradiated, and in the case of a linear heat ray. , Multiple bumps 1 in the longitudinal direction
Irradiate 5 at a time. By the irradiation of the heat ray 25, the bump 15 instantly rises to a temperature of around 250 to 300 ° C. and melts.

Next, as shown in FIG.
The bumps 15 irradiated with are melted to melt the lower glass substrate 2
A contact portion having a large contact area with the second peripheral electrode 23 is formed. Then, a liquid ultraviolet curable adhesive 26 is poured between the insulating film 14 of the glass substrate 11 around the melted bumps 15 and the lower glass substrate 22, and ultraviolet light 27 is irradiated from the transparent lower glass substrate 22 side. Adhesive 26
Adhesively fix. Then, if necessary, the lower glass substrate 2
The liquid encapsulant 28 is dropped into the gap between the glass substrate 11 and the glass substrate 11 for sealing. Other instant adhesives can also be used.

According to the circuit mounting method of the board having the above structure,
Bumps 15 for connection are formed on the comb-shaped connection electrodes 12 of the circuit pattern formed on the glass substrate 11, and the comb-shaped peripheral electrodes 23 of the substrate 20 and the corresponding bumps 15 of the glass substrate 11 are brought into contact with each other. By irradiating 15 with a spot-like heat ray to melt it and electrically connecting the corresponding electrodes 12 and 23, the spot-like heat ray 25 in the circuit mounting step allows the substrate 20 to be heated for a short time. Has a small adverse effect, and the bump 15 is melted to form a contact portion having a large contact area with the peripheral electrode 23. Therefore, the electrodes of both substrates are reliably electrically connected through the bump 15, and the connection is reliable. The property is also improved. Further, in this embodiment, by using the ultraviolet curing adhesive 26 or the instant adhesive, the bonding work is simplified and the mechanical fixation is surely performed. Since the glass substrate 11 has the same coefficient of thermal expansion as that of the liquid crystal panel 20, even if a large number of electrodes facing each other are connected at once, there is no problem due to thermal expansion as in the TAB method after the electrodes are bonded, and high accuracy is achieved. The good connection state can be maintained with the same as in the past.

In the above embodiment, the heating wire 25 is
Although the example of using the infrared light or the laser light converged in a spot shape or a linear shape has been described, it is not limited to the embodiment as long as it is a heat ray that melts the bump 15 portion.

Further, a liquid ultraviolet curable adhesive 26 is poured between the glass substrate 11 and the lower glass substrate 22 around the melted bump 15 and is irradiated with ultraviolet light 27 to fix the adhesive. At least, any instant adhesive or the like that can mechanically fix the glass circuit board 11 and the lower glass substrate 22 can be used.

Further, the glass substrate 11 may be provided with an arbitrary circuit pattern having comb-teeth-shaped electrodes such as output electrodes corresponding to the number of scan electrodes and data electrodes of the liquid crystal panel. When the area of the panel for use is large, the number of electrodes to be connected at a time is partially divided so that a plurality of glass substrates 11 are used. The repairability is improved by replacing only the glass substrate 11 in that portion.

In the above embodiments, the liquid crystal display panel has been described as an example, but a liquid crystal television or other flat panel such as a plasma display, an EL display, an LED display, etc., and a liquid crystal sensor or a liquid crystal shutter other than the display panel. Etc. can be applied to those connecting a large number of comb-shaped electrodes.

Further, if the comb-shaped peripheral electrode 23 on the lower glass substrate 22 side is subjected to a metal coating process for solder bonding,
The bumps may be electrically connected by melting, and in that state, they may be fixed with an instant adhesive.

[0026]

As described above, according to the present invention, bumps are formed on the comb-shaped connection electrodes of the circuit pattern formed on the glass substrate, and the comb-shaped peripheral electrodes of the substrate and the corresponding bumps of the glass substrate are formed. By bringing them into contact and irradiating them with spot-shaped or line-shaped heat rays to melt them and electrically connecting the corresponding electrodes, there is little adverse effect on the board due to heat during circuit mounting, and The electrical connection of the electrodes on the substrate is also surely made through the bumps, which has the effect of improving reliability.

[Brief description of drawings]

FIG. 1 is a process diagram showing a circuit mounting method according to an embodiment of the present invention.

FIG. 2 is a perspective view of a glass circuit board according to an embodiment of the present invention.

FIG. 3 is a perspective view showing a manufacturing process of the glass circuit board according to the embodiment of the present invention.

[Explanation of symbols]

 10 Glass Circuit Board 11 Glass Substrate 12 Output Electrode 13 Input Electrode 14 Insulating Film 15 Bump 16 Semiconductor Chip 17 Projection Electrode 18 Liquid Sealant 20 Liquid Crystal Panel 21 Upper Glass Substrate 22 Lower Glass Substrate 23 Electrode 24 Heat Ray Source 25 Heat Ray 26 Adhesion Agent 27 ultraviolet light 28 liquid encapsulant 30 glass substrate

Claims (1)

[Claims] 1. A method for mounting a circuit around a substrate on which an electrode pattern having a comb-teeth peripheral electrode is formed, wherein the substrate is an elongated plate-shaped glass substrate extending in a lateral direction or a sub-direction around the substrate. Forming a circuit pattern having a comb-teeth connecting electrode having the same pitch interval as the comb-teeth peripheral electrode, forming bumps on each of the comb-teeth connecting electrodes of the circuit pattern; A step of directly mounting the circuit, a step of bringing the comb-shaped peripheral electrodes of the substrate into contact with corresponding bumps of the glass substrate, irradiating the bumps with heat rays to melt, and the substrate and the glass substrate after the step And a circuit mounting method for a substrate, the method comprising: