JP3797742B2 - Manufacturing method of liquid crystal display panel - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a liquid crystal display panel. More specifically, the present invention relates to a manufacturing method for forming a metal electrode film for directly connecting a liquid crystal display panel and an external mother substrate on a side surface of the substrate on the liquid crystal display panel side.
[0002]
[Prior art]
A mother board (provided with circuits and electrodes for driving and controlling the liquid crystal display panel) equipped with a large number of display electrode terminal groups provided at the edge of the glass substrate of the liquid crystal display panel and an external circuit for supplying display information and power The connector structure is used almost without exception for the connection with the electrode group provided on the printed circuit board).
[0003]
Main examples of commonly used connector structures are: (1) zebra rubber (a prismatic structure in which a number of insulating and conductive rubbers are alternately stacked in the longitudinal direction) and the electrode terminal surface on the bottom surface of the liquid crystal display panel. A structure in which the electrodes are pressed together with the electrode group on the upper surface of the mother board, and the corresponding electrodes are connected by elastic contact of the conductive rubber part.
(2) One edge of a flexible sheet substrate (multiple lead wiring is formed between both ends on a thin and flexible substrate surface made of polyimide resin or polyester resin) is anisotropic. A structure in which a conductive sheet (ACF) is used as an intermediate to heat-press the electrode terminal surface of the liquid crystal display panel or apply a silver paste to solidify by heating, and connect the other edge to the electrode group of the mother substrate. Etc.
[0004]
These conventional techniques have the following problems. In the conventional example (1), the connector is flexible and easily deformed, and a metal plate or a resin frame-like member (requiring a molding die) is used to maintain the shape and the crimping force. Takes time. In the conventional example (2), the FPC or the like is punched with a mold, and the liquid crystal display panel must also be supported with another structure. That is, in any of the conventional examples, a connector and a frame part are required in addition to the display panel body, and a die is involved, which is expensive.
[0005]
In designing the entire liquid crystal display device, we are in charge of the design of the liquid crystal display panel and connectors, as well as the set manufacturer who is responsible for the design of the entire device including the motherboard, in consideration of the selection of connectors and the support method of the liquid crystal display panel. Consultation with LCD panel parts manufacturers is also necessary. Therefore, the design around the display is heavy in design and load (large time cost), high customizability for each set, and it is difficult to standardize the shape and specifications of parts, which is extremely desirable for parts manufacturers. It was difficult to reduce the cost because of the large number of points and inferior processing and assembly.
[0006]
Other electronic components are naturally mounted on the mother board, but they are usually SMD (surface mounted device) and can be easily automated using a robot and a solder reflow furnace. However, since the heat resistance of the liquid crystal panel is poor, in the conventional technique using a connector, such a method cannot be connected by individual soldering as a step ahead. The fact that the connection of the liquid crystal display panel cannot be mounted on the mother substrate at the same time as mounting of other elements or by a method according to other elements has hindered improvement in productivity and cost reduction of the display device.
[0007]
In addition, the liquid crystal display device includes functional elements having a close relationship with the liquid crystal display panel, such as a backlight element that illuminates a display that is an LED lamp element or an EL panel, or a detection element for a touch switch that is a touch panel or a touch sensor. In many cases, however, these functional elements cannot be directly connected to the liquid crystal display panel using solder, conductive adhesive or the like, mainly because the liquid crystal panel has poor heat resistance.
[0008]
Japanese Patent Laid-Open No. 3-282419 “Liquid Crystal Display” is a conventional example proposed. In this conventional example, as shown in FIG. 1, an EL backlight panel is disposed on the back surface of a liquid crystal display panel, and both edges thereof are inserted into concave grooves of a connector and held. As another conventional example, there is Japanese Patent Application No. 9-44903 filed by the present applicant and not yet published. This discloses a structure in which an electrical connection of a light emitting element for illumination to a mother substrate is made through a connector fixed to a liquid crystal display panel.
[0009]
In these conventional examples, there is an advance as a structure for holding and connecting a functional element attached to the liquid crystal display panel, and there is an advantage that other constituent members for holding and connecting can be omitted. Since this is done, a connector is essential, and the disadvantages associated with the cost and design cost of the connector cannot be overcome.
[0010]
[Problems to be solved by the invention]
An object of the present invention is to omit a connector structure associated with a liquid crystal display device, and to form a metal electrode film that can be directly connected to a mother substrate or a functional element by soldering or a thermosetting conductive adhesive on the liquid crystal display panel side. As a result, an object of the present invention is to obtain a liquid crystal display device capable of greatly reducing manufacturing costs and time costs with a configuration that is extremely simplified with a small number of parts.
[0011]
[Means for Solving the Problems]
(1) In the manufacturing process of the upper glass substrate or the lower glass substrate constituting the liquid crystal display panel, a step of forming an ITO electrode film on one surface of a large glass substrate, a step of drilling a large number of through holes in the terminal electrode portion, Screen-printing a conductive paste containing a metal material so as to cover a part of the ITO electrode film and the through hole, and vacuum suction from the other surface of the large glass substrate to coat the conductive paste inside the through-hole In the same way, printing the conductive paste on the other surface of the large glass substrate, firing the conductive paste on both sides, cutting the large glass substrate along the surface passing through the center of the through-hole, A step of separating the substrate.
(2) In (1), the metal material is silver palladium.
(3) The large glass substrate is cut on the surface passing through the center of the through hole in (1).
(4) In (1), including a step of fixing a heat-resistant polarizing plate to the upper surface or lower surface of the liquid crystal display panel.
(5) The through hole drilling, conductive paste printing, and firing steps of (1) are arranged between the electrode etching and alignment layer forming steps and the sealant printing and common electrode printing steps.
(6) Instead of forming electrodes in a large number of small hole through holes, a process of drilling long hole through holes, a process of transferring and printing a conductive paste in stripes on the inner wall surface, and a process of plating treatment were provided. .
[0012]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1A is a plan view of a completed liquid crystal display panel to which the manufacturing method of the present invention is applied, and FIG. 1B is a sectional view taken along the line AA. In the figure, 1 is an upper glass substrate of a liquid crystal display panel, and 2 is a lower glass substrate, and a liquid crystal material (not shown) is held in the gap. Reference numeral 3 denotes a lower ITO electrode (transparent conductive film) formed on the upper surface of the lower glass substrate 2. Reference numeral 4 denotes a through-hole which is opened and cut in the lower glass substrate before being cut. Reference numeral 5 denotes a silver palladium electrode, which partially overlaps the lower ITO electrode and overlaps the inner wall of the through-hole 4. A large number of them are formed at a predetermined pitch in the vicinity of both end faces. Reference numeral 6 denotes an upper polarizing plate attached to the upper surface of the upper glass 1.
[0013]
The connection state of the liquid crystal display panel will be described below with reference to the cross-sectional view of (b). The mother board and the like are drawn with dotted lines (instead of imaginary lines). 7 is a mother substrate, and 8 is a mother substrate electrode formed on the upper surface thereof, which is a general copper foil pattern. The planar arrangement of the portion overlapping the liquid crystal display panel is the same pitch and coincides with the silver palladium electrode 5. Are arranged to be. Reference numeral 9 denotes solder, which connects one silver palladium electrode 5 and one mother substrate electrode 8 formed on the inner wall surface of the through hole 4 one by one.
[0014]
Of the elements constituting the liquid crystal display panel, the upper polarizing plate 6 and the lower polarizing plate (not shown) are usually low in heat resistance except for the liquid crystal material. In order to improve this, the base material of a polarizing plate can be made into the polyimide resin which is a material with high heat resistance. Although the translucency of the polyimide resin is slightly inferior, it can be solved by reducing the thickness to about several tens of μm.
[0015]
FIG. 2 is a main manufacturing process diagram of a glass substrate as an example of the embodiment of the present invention. 3 is a plan view of the large glass substrate that has been subjected to step 3, FIG. 4 is a plan view of the large glass substrate that has been subjected to step 4, and FIG. 5A is a state in which step 5 has been performed. (B) is sectional drawing of the through-hole part of the large glass substrate of the state which performed the process 6. FIG. The manufacturing process will be described below with reference to the drawings.
[0016]
A large number of upper and lower glass substrates are simultaneously formed on the surface of a large glass substrate having a size of 250 mm × 200 mm, for example, and finally separated individually. In FIGS. 3 and 4, the upper glass substrate and the lower glass substrate are drawn together in one large glass substrate, but this is for convenience of explanation. The yield will be better if only the glass substrate is made.
[0017]
In FIG. 2, step 1, ITO electrodes are deposited on the surface of the large glass substrate, and in step 2, they are etched into a required pattern. In step 3, an alignment layer for aligning liquid crystals is processed and formed. The state at the end of this step is shown in FIG. In FIG. 3, reference numeral 10 denotes a large glass substrate, in which the predetermined outlines of the upper glass substrate 1 and the lower glass substrate 2 to be finally cut and separated are indicated by thin solid lines. Reference numeral 3 denotes a patterned ITO electrode, but the portion related to display is not shown, and only the portion that becomes the lead line is shown by a thin solid line.
[0018]
In step 4 of FIG. 2, a number of through holes are drilled using a drill. The hole diameter is 0.3 mm or more, for example 0.5 mm. (In this case, the pitch of the hole rows, that is, the distance between the display lead terminals is 0.6 mm or more and 1.5 mm or less, for example, about 0.8-1 mm, although it depends on the hole diameter. This is enough for a display device that has a simple display pattern or LCD driver IC mounted on the liquid crystal display panel to reduce the number of input / output terminals to the liquid crystal display panel. This is shown in FIG.
[0019]
In step 5 of FIG. 2, a conductive paste containing silver palladium is applied around the through hole 4 on the upper surface of the large glass substrate by screen printing. At this time, vacuum suction is performed from the lower surface of the large glass substrate 10 so that the conductive paste covers the inner wall surface of the through hole. This state is shown in FIG. Since the conductive paste around the hole is partially overlapped with the upper ITO electrode 3, both of them are conducted, and the silver-palladium electrode 5 becomes a terminal of the display lead line after completion. Next, when the same operation is performed on the lower surface of the large glass substrate 10 in step 6, the conductive paste completely covers the inner wall surface of the through hole 4. This state is shown in FIG.
[0020]
In step 7 of FIG. 2, the applied conductive paste is baked to complete the silver palladium electrode 5. The firing temperature is about 500 ° C. which is lower than the transition temperature (Tg) of about 560 ° C. of the glass material for liquid crystal display panels. The firing temperature of silver palladium has been 700-750 ° C. in the past, but the recent development of materials for low temperature firing has also enabled the present invention.
[0021]
Since it is the same as the prior art, a brief description will be given below. In FIG. 2, step 8 is a sealant printing for creating a liquid crystal injection space, a step 9 is printing a common electrode, and a step 10 is bonding a large glass substrate (an upper glass substrate planned portion and a lower glass substrate on different large glass substrates) In step 11, liquid crystal is injected and sealed, in step 12, cut and separated into a single liquid crystal display panel is performed, and in step 13, upper and lower polarizing plates are pasted, A finished liquid crystal display panel is obtained.
[0022]
Cutting is performed using a slicer or the like, but the predetermined cutting line passes through the center of the through hole 4, so each through hole is divided into two parts, and the silver-palladium electrode formed on the inner wall surface is separated as shown in FIG. A terminal electrode group which is exposed on the side surface of the liquid crystal display panel and can be soldered according to the present invention is obtained. This is the end of the description of an example of the embodiment.
[0023]
Next, although not in the manufacturing process of the liquid crystal display panel, the soldering process between the completed liquid crystal display panel and the mother substrate will be described. Soldering is preferably performed by positioning the LCD panel on the mother board 9 and placing it through a solder reflow furnace if the entire LCD panel allows heat resistance, but if the heat resistance is still severe, use an air gun or the like by hand. You can also solder quickly. In order to prevent the glass from cracking or cracking, it may be preheated to a heat resistant temperature of the liquid crystal, for example, 100 to 120 ° C., or may be subjected to solder plating on the silver palladium electrode. Further, only the silver-palladium electrode turned to the lower surface of the lower glass substrate by controlling the amount of solder may be connected to the mother substrate electrode.
[0024]
Next, another embodiment of the present invention will be described. The metal electrode provided on the side surface by the through hole is used not only for connection to the mother substrate but also for mounting an element for illumination or touch detection on the liquid crystal display panel. When the functional element is mounted on the upper glass, the control signal is still supplied from the mother board, so the connection pattern is the mother board, the lower glass board through hole, the through hole provided in the upper glass board and the two-stage through It will be connected to this element via a hole. Providing a through hole in the upper glass substrate and forming a metal film can be performed at the same time as the process for the lower glass substrate already described.
[0025]
In addition, the material of the metal electrode film serving as the terminal electrode may be one other than silver palladium. In addition, as a method of manufacturing a terminal electrode group that can be soldered, a straight long hole is drilled instead of a through-hole array on the smooth side surface of the upper or lower glass substrate that has been cut in advance without using a small hole through-hole. A metal film may be formed on the smooth inner wall surface of the long hole of the large glass substrate in the state (through side). For example, the silver paste is transferred and printed on the smooth side surface of the glass substrate in stripes separated in the direction of the glass substrate surface, fired, and further plated with copper, nickel or the like, and then solder plated. In short, it is only necessary to form a metal film having the necessary heat resistance and strength near the side surface of the glass substrate.
[0026]
【The invention's effect】
In the present invention, since the manufacturing process of the liquid crystal display panel capable of directly connecting the liquid crystal display panel and the mother substrate is realized, the following effects can be obtained.
(1) The liquid crystal display panel can be supported and connected to the mother substrate without using a connector or a connection member, and the configuration and connection work of the display device are significantly simplified.
(2) As a result, a significant cost reduction of the display device can be achieved.
(3) Both the set maker and the parts maker reduce the design load and shorten the delivery time.
(4) Since there is no connector and no support frame for the liquid crystal display panel is required, an ultra-thin display body structure is possible.
(5) The technology of the present invention has a wide range of applications, and can be applied to a structure in which functional elements such as illumination elements and touch detection elements are directly mounted on a liquid crystal display panel, and in that case also a structure that is extremely simplified Can be realized.
[Brief description of the drawings]
1A is a plan view of an example of a liquid crystal display panel to which the present invention is applied, and FIG. 1B is a cross-sectional view taken along line AA in FIG.
FIG. 2 is a manufacturing process diagram of a liquid crystal display panel as an example of an embodiment of the invention.
FIG. 3 is a plan view of a large glass substrate after a third step in the manufacturing process.
FIG. 4 is a partial plan view of a large glass substrate after the fourth step in the manufacturing process.
5A is a cross-sectional view of a large glass substrate after the fifth step and FIG. 5B, after the sixth step, during the manufacturing process.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Upper glass substrate 2 Lower glass substrate 3 Lower ITO electrode 4 Through hole 5 Silver palladium electrode 6 Upper polarizing plate 7 Mother substrate 8 Mother substrate electrode 9 Solder 10 Large glass substrate

Claims (6)

In the manufacturing process of the upper glass substrate or the lower glass substrate constituting the liquid crystal display panel, the step of forming the ITO electrode film on one surface of the large glass substrate, the step of drilling a large number of through holes in the terminal electrode portion, and the metal material are included. A step of screen-printing a conductive paste so as to cover a part of the ITO electrode film and the through-hole, a step of covering the through-hole with the conductive paste by performing vacuum suction from the other surface of the large glass substrate , A process of printing and forming a conductive paste on the other side of the large glass substrate, a step of firing the conductive paste on both sides, and cutting the large glass substrate along a plane passing through the center of the through-hole. A method for producing a liquid crystal display panel, comprising a step of separating the substrate of the liquid crystal panel. The method for manufacturing a liquid crystal display panel according to claim 1, wherein the metal material is silver palladium. The method for manufacturing a liquid crystal display panel according to claim 1, wherein the glass substrate is cut along a plane passing through the center of the through hole. A step of laminating and bonding an upper glass substrate and a lower glass substrate of the substrate of the liquid crystal panel, a step of encapsulating a liquid crystal material in a gap between the substrates, and a step of fixing a heat-resistant polarizing plate to the surface The manufacturing method of the liquid crystal display panel of Claim 1 containing this. In the manufacturing process of an upper glass substrate or a lower glass substrate constituting a liquid crystal display panel, a process of forming an ITO electrode film on one surface of a large glass substrate, a process of etching the ITO electrode film, the etched ITO electrode film and etching Forming an alignment layer on the exposed large glass substrate surface, drilling a plurality of through-holes in the terminal electrode portion, conducting paste containing a metal material with a part of the ITO electrode film and the through-hole A step of screen printing so as to cover the hole, a step of vacuum suction from the other surface of the large glass substrate to coat the conductive paste inside the through hole, and a conductive page on the other surface of the large glass substrate in the same manner. The process of printing the strike, the process of firing the conductive paste on both sides, and the sealant for encapsulating the liquid crystal material is printed on the surface of the large glass substrate A step of printing a common electrode, a step of bonding two substrates, a step of injecting a liquid crystal material into a space formed by the bonding and sealing the injection hole, and the large glass substrate at the center of the through hole The liquid crystal display panel manufacturing method including the process of cut | disconnecting in the surface which passes along and isolate | separating into the board | substrate of each liquid crystal panel. In the manufacturing process of the upper glass substrate or the lower glass substrate constituting the liquid crystal display panel, the step of forming the ITO electrode film on one surface of the large glass substrate, the step of drilling the long hole of the terminal electrode part, the metal material A step of transferring and printing a conductive paste containing a large number of stripes on the surface of the large glass substrate and an inner wall surface of the elongated hole, a step of firing the conductive paste, a step of further plating the fired conductive paste surface, A method for manufacturing a liquid crystal display panel, comprising a step of cutting a large glass substrate along a plane passing through the center of the elongated hole through hole and separating the large glass substrate into individual liquid crystal panel substrates.

Images