JPH07297541A - Method for mounting circuit on board - Google Patents

Abstract

PURPOSE:To improve the reliability of the electrical connections of comb-tooth-like peripheral edge electrodes of a first board with the electrodes of a second glass board which are opposed to the electrodes of the first board respectively, without the wrong effects of the heatings applied to both the boards, by contacting the electrodes of the first board with the opposite solder bumps set on the electrodes of the second glass board, and by crushing the top parts of the solder bumps through crimping forces, and further, by connecting the respective opposite electrodes of both the boards with each other electrically, and thereafter, by fixing the second glass board on the first board through a curing agent. CONSTITUTION:A slender plate-like glass board 11 is set on a board 20 along its lateral or longitudinal periphery and it has the same thermal expansion coefficient as the board 20. A circuit pattern is formed on this glass board 11. This circuit pattern has comb-tooth- teeth-like connective electrodes 12 whose teeth pitch intervals are the same as comb-tooth-like peripheral edge electrodes 23 of the board 20. Subsequently, on each of the comb-tooth-like connective electrodes 12 of the glass board 11, a solder bump 15 is formed. Then, each of the comb-teeth-like electrodes 23 of the board 20 is contacted with the solder bump 15, and crimping forces P are applied to them from above the bump 15 and from under the electrode 23, and as a result, by the crushing of the top part of the solder bump 15, both the electrodes 12, 23 are connected with each other. Thereafter, the glass board 11 is fixed on the board 20 by a curing agent filled into the space between both the boards 11, 20, and thereby, the reliabilities of their electrical connections are improved without the wrong effects brought by their heatings.

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 driving circuit or the like on a substrate used for various flat panel displays, liquid crystal sensors, liquid crystal shutters, etc., and other high density mounting.

[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 that form a large number of display dots (pixels) normally arranged in a matrix on a transparent glass substrate are patterned with high precision, and the comb-teeth-shaped electrodes on the periphery of the substrate are formed. A drive circuit or the like is connected to.

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 on 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 is connected to an electrode portion around the display substrate by soldering or thermocompression bonding, or a bare circuit element (bare chip) is used. A COG (Chip On Glass) method or the like, which is directly mounted on the peripheral edge of the display substrate, has been 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 chip interval in a wide area. Connection becomes difficult, and a malfunction occurs after connection, and the pitch is about 100 μm. Further, in the COG method, since the element is directly mounted on the glass substrate for display, it becomes difficult to inspect, replace or repair (repair) the defective integrated circuit.
In addition, it is necessary to change the circuit pattern on the glass substrate side for display in accordance with the design of the integrated circuit, and a part of the glass substrate having a large area becomes defective, resulting in poor yield and poor cost. There was a problem that it became difficult to make it.

In contrast, US Pat. No. 5,084,9
In No. 61, a circuit pattern having comb-teeth connecting electrodes having the same pitch interval as the comb-teeth peripheral electrodes of the substrate was formed on an elongated glass substrate having the same coefficient of thermal expansion as that of the substrate, and the necessary circuits were directly mounted. After that, an anisotropic conductive adhesive containing metal particles and the like is applied between the comb-teeth peripheral electrode of the substrate and the corresponding comb-teeth connection electrode of the circuit board. A technique relating to a circuit mounting method of substrates to be electrically 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.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a circuit mounting method for a substrate, which can improve the reliability of electrical connection without adversely affecting the substrate by heat.

[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. A circuit pattern having comb-teeth connection electrodes with the same pitch interval as the comb-teeth peripheral electrode of the substrate is formed on a glass substrate having a long and narrow plate shape having the same coefficient of thermal expansion along the horizontal direction or the longitudinal direction around the substrate. The step of forming solder bumps on each of the comb-shaped connecting electrodes of the glass substrate, the comb-shaped peripheral electrodes of the substrate and the solder bumps formed on the corresponding comb-shaped connecting electrodes of the glass substrate. And a step of applying a pressing force between the two substrates to crush the top of the solder bump to connect the two electrodes, and a curing agent between the substrate and the glass substrate after the connecting step. Those comprising the step of constant.

It is preferable that a plurality of the solder bumps be formed along the comb-teeth-shaped connection electrode. Further, it is preferable that the solder bumps are formed in a comb shape so as not to overlap with the adjacent comb-teeth connection electrodes along the comb-teeth connection electrodes.

[0010]

In the present invention, solder 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 and the corresponding solder bumps of the glass substrate are brought into contact with each other, and a crimping force is applied. The top of the solder bump is crushed, the corresponding electrodes are electrically connected, and then the substrate and glass substrate are fixed with a curing agent, so that the substrate is not adversely affected by heat and the electrical connection is maintained. Reliability is increased.

By forming a plurality of the solder bumps along the comb-teeth connection electrodes, the connection is further ensured. Further, the solder bumps are connected to the comb-teeth connection electrodes adjacent to each other along the comb-teeth connection electrodes. By forming the chips so that they do not overlap each other, there is no risk of electrical conduction between adjacent electrodes.

[0012]

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 a board for mounting a drive circuit of a liquid crystal display panel, for example, and has the same coefficient of thermal expansion as that of the 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 comb-teeth connection electrodes 12 on the output side are formed with the same pitch as the scanning electrodes and the data electrodes, and on the other side, the comb-shaped connection electrodes 12 on the input side are connected along the longitudinal direction to, for example, a control circuit provided on a printed circuit board. A comb-shaped connection electrode 13 is formed.

FIG. 3 is a diagram for explaining the manufacturing process of the glass circuit board of the embodiment of the present invention.

As shown in FIG. 1A, a glass substrate 30 having a large area having the same coefficient of thermal expansion as that of the liquid crystal panel is provided on the glass substrate 30.
A large number of circuit patterns as shown in FIG. 2 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), and the glass substrate 30 shown in FIG.
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, an insulating film 14 is formed by a known technique on the circuit pattern of the glass circuit board 10 formed as shown in FIG. Through holes are formed in corresponding portions of the semiconductor bare chip and the comb-shaped connection electrode 12 on the output side,
Protrusion-shaped solder bumps 15 for connection are formed by solder dams in the through holes. In the figure, the solder bumps for connection to the comb-teeth-shaped connection electrode 13 on the input side are not shown.

Next, as shown in FIG. 1B, the required number of semiconductor chips 16 for liquid crystal drive circuits are mounted on the glass circuit board 10. As a method of mounting the chip 16, for example, the protruding electrode 1 formed on the semiconductor chip 16 is used.
7 is brought into contact with the corresponding solder bump 15 and heat-bonded, and then the liquid sealing agent 18 is dropped to seal the semiconductor chip 16. Note that as another mounting method of the semiconductor chip 16, 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 2
Lower glass substrate 22 around the periphery of the liquid crystal panel 20
A region for mounting a drive circuit is formed on the comb-shaped peripheral electrode 23 of the lower glass substrate 22, and the comb-shaped connection electrode 12 on the output side of the glass substrate 11 is formed on the end of the comb-shaped peripheral electrode 23.
Align and contact the corresponding solder bumps 15,
Then, a pressing force P is applied from above and below by a predetermined pressing means using hydraulic pressure or the like to crush the top of the solder bump 15 and connect it to the comb-teeth peripheral electrode 23.

Next, as shown in FIG. 3D, the insulating film 14 of the glass substrate 11 around the crushed solder bumps 15 is formed.
A liquid ultraviolet curable adhesive 24 is poured between the lower glass substrate 22 and the lower glass substrate 22, and ultraviolet light 25 is irradiated from the transparent lower glass substrate 22 side to solidify the adhesive. The adhesive 24 may be applied in advance in the previous step, and the top of the solder bump 15 may be crushed later by a pressing means. Thereafter, if necessary, the liquid sealing agent 24 is dropped into the gap between the lower glass substrate 22 and the glass substrate 11 to seal the liquid.

FIGS. 4 to 6 are views for explaining specific examples of solder bumps formed on the electrodes of the present invention. FIG. 4 is a plan view of an electrode portion on which the solder bumps are formed, and FIG. 5 is an enlarged sectional view of the solder bump portion. 6 and 6 are views in which the height of the solder bump is measured. The parts corresponding to those in FIG. 1 are designated by the same reference numerals.

On the surface of the glass substrate 11 on which the comb-teeth-shaped connection electrode 12 on the input side is formed, an insulating film 14 made of, for example, polyimide, various resists, an oxide film or the like and having a thickness of about 1 μm is formed. In the insulating film 14 on the tooth-shaped connecting electrode 12, a plurality of circular through holes of about 40 μm are formed so as to be adjacent to each other between the comb-shaped tooth-shaped connecting electrodes 12 which are adjacent to each other at regular intervals. Soak. As a result, the solder bumps 15 are formed in the through holes so as to have a predetermined height (h) above the surface of the insulating film 14. Such an input-side comb-shaped connecting electrode 12
Is made of a material such as copper, nickel, or gold that adheres to solder. For example, the width is 60 μm and the pitch is 80 μm.
The Ni (nickel) film having a thickness of about 0.5 μm and the Au (gold) film having a thickness of about 0.05 μm are sequentially laminated. As the type of solder, for example, P
b (lead) 40% and Sn (tin) 60% are used. Solder bump 1 formed under the above conditions
The height of No. 5 was about 4 μm to 8 μm as shown in FIG. FIG. 6 shows the height of the solder bumps 15 formed along the input-side comb-teeth-shaped connection electrode 12 at intervals of approximately 150 μm (interval of peaks in the horizontal axis of FIG. 6) (peaks in the vertical axis of FIG. 6). Height) is actually measured. It was confirmed that the height of the solder bump is generally determined by the size (area) of the through hole, and becomes smaller as it becomes smaller. It should be noted that although solder bumps having a size corresponding to the width and pitch of the connection electrodes are used, it has been confirmed that the diameter can be 20 μm or less, and the width of the connection electrodes is 30 μm or less and the pitch is 50 μm or less. Can be applied to things.

According to the circuit mounting method of the board having the above structure,
A protrusion-shaped connection solder bump 15 is formed on the comb-shaped connection electrode 12 of the circuit pattern formed on the glass substrate 11,
The comb-teeth-shaped peripheral electrode 23 of the substrate 20 and the corresponding solder bump 15 of the glass substrate 11 are brought into contact with each other, and a pressing force is applied to crush the top of the solder bump 15 so that the corresponding electrode 12,
23 are connected to each other, and the adhesive is applied in advance or fixed by an adhesive 24 such as an ultraviolet curing type which is poured after crushing the top of the solder bump 15. Therefore, heating is not performed at all during the electrode connecting step, the thermal adverse effect on the substrate 20 is eliminated, and the top portion of the solder bump 15 is flattened to flatten the portion. The area in contact with the electrode 23 is increased, and electrical connection is ensured. Further, as shown in FIG. 4, when a plurality of solder bumps 15 are formed along the comb-teeth-shaped connection electrode 12 at regular intervals, an electrical connection failure is more likely to occur than when one solder bump 15 is formed. Less,
The connection reliability can also be improved. In this embodiment, by using the ultraviolet curing adhesive 24, the bonding work is simplified and the mechanical fixing is surely performed. The glass substrate 11
Has the same coefficient of thermal expansion as the liquid crystal panel 20, so that even if a large number of electrodes are connected at once in a large area, there is no problem due to thermal expansion as in the TAB method after the electrodes are connected, and high-accuracy and good connection is possible. The state can be maintained as in the past.

7 and 8 are views for explaining solder bumps of another embodiment of the present invention.

As shown in FIG. 7, a plurality of circular solder bumps 41 are alternately arranged on the input-side comb-teeth-shaped connecting electrode 12 at regular intervals so as not to overlap between adjacent electrodes 12 and 12. It is formed in the shape of a bird. In addition, as shown in FIG. 8, on the input-side comb-teeth-shaped connection electrode 12,
Elliptical solder bumps 51 that are long in the direction along the electrode 12 are formed in a striped shape.

Since the glass circuit board on which the solder bumps 41 and 51 are formed is formed in a striped shape, even if the tops of the solder bumps 41 and 51 are largely crushed, the solder bumps between the adjacent comb-teeth connecting electrodes 12 are formed. Four
There is no danger of short-circuiting between 1,51 comrades. Even when the solder bumps 41 and 51 are largely crushed and overlapped on the adjacent comb-teeth-shaped connection electrode 12, there is no possibility of conduction with each other because of the insulating film. Further, the elliptical solder bump 51 can increase the contact area to ensure the connection.

Although the solder bump has a circular shape or an elliptical shape in the above embodiment, the shape, size, position and number of the comb-shaped connecting electrode 12 can be arbitrarily set. The crimping force for crushing and connecting the solder bumps is
Depending on the total number and shape of these solder bumps,
It is sufficient that at least the top is flattened and flattened, and an appropriate value is experimentally determined.

The glass substrate 11 around the solder bumps
A liquid ultraviolet curable adhesive 24 is poured between the lower glass substrate 22 and the lower glass substrate 22 and is fixed by irradiating with ultraviolet light 25. However, before the top of the solder bump is crushed, the adhesive 2
4 may be applied and then pressure-bonding force may be applied by a pressing means to connect, and at least the glass circuit board 11 and the lower glass substrate 22 may be mechanically fixed to each other without applying heat. Instant adhesive etc. can be used.

Further, the glass circuit board 10 may be formed with any circuit pattern having comb-teeth peripheral electrodes such as output electrodes in a number corresponding to the number of scan electrodes and data electrodes of the liquid crystal panel. When the area of the display panel is large, the number of electrodes to be connected at one time is partially divided so that a plurality of glass circuit boards 10 are used. The repairability is improved by replacing only that portion of the glass substrate 11.

In the above embodiments, the liquid crystal display panel has been described as an example, but a flat panel such as a liquid crystal television or other plasma display, EL display, 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.

Although the electrodes are connected to each other in the present embodiment, the present invention can be applied to the connection technique of the semiconductor chip and the electrodes or the chip connection technique in high-density mounting.

[0033]

As described above, according to the present invention, the solder bumps are formed on the comb-shaped connecting electrodes of the circuit pattern formed on the glass substrate, and the comb-shaped peripheral electrodes of the substrate and the corresponding solder bumps of the glass substrate are applied. Contact and squeeze the top of the solder bumps by applying pressure to electrically connect the corresponding electrodes, and then fix the substrate and glass substrate with a curing agent, which adversely affects the substrate due to heat. There is an effect that the reliability of the electrical connection can be improved without the need.

[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 diagram illustrating a manufacturing process of the glass circuit board according to the embodiment of the present invention.

FIG. 4 is a plan view of an electrode portion having a solder bump according to an embodiment of the present invention.

FIG. 5 is an enlarged cross-sectional view of a solder bump portion of the embodiment of the present invention.

FIG. 6 is a diagram showing a result of measuring the height of a solder bump according to an example of the present invention.

FIG. 7 is a diagram illustrating a circular solder bump according to another embodiment of the present invention.

FIG. 8 is a diagram illustrating an elliptical solder bump according to another embodiment of the present invention.

[Explanation of symbols]

 10 Glass Circuit Board 11 Glass Substrate 12, 13 Comb-Shaped Connection Electrode 14 Insulating Film 15 Solder Bump 16 Semiconductor Chip 17 Projection Electrode 18 Liquid Sealant 20 Liquid Crystal Panel 21 Upper Glass Substrate 22 Lower Glass Substrate 23 Comb-shaped Perimeter Electrode 24 Adhesion Agent 25 ultraviolet light 26 liquid encapsulant 30 glass substrate 41,51 solder bump

Claims (3)

[Claims] 1. A method of mounting a circuit around a substrate on which an electrode pattern having a comb-teeth peripheral electrode is formed, wherein the substrate has an elongated plate shape along the horizontal direction or the vertical direction and has the same coefficient of thermal expansion. A step of forming a circuit pattern on a glass substrate having a comb-shaped connecting electrode having the same pitch interval as the comb-shaped peripheral electrode of the substrate; and a step of forming solder bumps on the comb-shaped connecting electrodes of the glass substrate, respectively. , The comb-shaped peripheral electrodes of the substrate and the solder bumps formed on the corresponding comb-shaped connecting electrodes of the glass substrate are brought into contact with each other, and a crimping force is applied between the substrates to crush the tops of the solder bumps so that the distance between the electrodes is reduced. A circuit mounting method for a substrate, comprising a step of connecting and a step of fixing the substrate and the glass substrate with a curing agent after the step of connecting. 2. The circuit mounting method for a substrate according to claim 1, wherein a plurality of the solder bumps are formed along the comb-teeth-shaped connection electrode. 3. The circuit mounting method for a substrate according to claim 1, wherein the solder bumps are formed in a crimp shape so as not to overlap with the adjacent comb-teeth connecting electrodes along the comb-teeth connecting electrodes.