JPH11305181A - Method for setting cutting condition of liquid crystal display panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To rapidly determine cutting conditions by analyzing deformations of a liquid crystal display panel by using an infinite element method, predicting cutting performance of the liquid crystal panel from stress intensity factors of scribe tips derived from node displacement on the scribed surface, and programming a scriber, etc. SOLUTION: A finite element model of a LCD panel is prepared. A material constant, namely, a coefficient of elasticity as a mechanical-property value of a composition material, Poisson's ratio, is inputted. Deformation of the LCD panel due to a breaking load is analyzed by using the prepared finite element model and a finite element method, and a node displacement of a scribed surface is calculated. Stress intensity factors K1, K2 at the tips of the scribes (depths of cut 4a, 4b) are calculated from the node displacement. In the case of scribe- breaking process of the LCD panel, out-of-plane shear deformation is negligible, therefore, cutting directions of stress indices (K1, K2) of aperture type and in-plane shear deformations are predicted. If cutting is possible, process conditions are set, and a scriber, etc., are programmed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cutting condition setting method for cutting a liquid crystal display panel by a scribe-break method.

[0002]

2. Description of the Related Art In a manufacturing process of a liquid crystal display panel (hereinafter, referred to as an LCD panel), there is a step of cutting only one side of two bonded glass substrates. A break method is used. In the drawing, 1 is a cutter made of carbide or diamond, 2a and 2b are glass substrates constituting a display driving substrate or a counter substrate or the like bonded together by a sealing material 3, 4 is a cut formed by the cutter 1,
Reference numeral 5 denotes a squeegee for applying a load from the glass substrate 2b opposite to the glass substrate 2a in which the cuts 4 are formed. Generally, the scribe-break method firstly uses the method shown in FIG.
As shown in FIG. 5A, scribing is performed by the cutter 1 of the scribing device, and a cut 4 is made along a cutting line on the glass substrate 2a. Next, as shown in FIG. 15 (b), the cut 4 is placed on a table of a breaking device with the cut 4 down, and a squeegee is dropped on the cut 4 from the glass substrate 2b on the opposite side to apply an impact load. As a result, the crack propagates from the notch 4 as a starting point, the glass substrate 2a is divided (breaked), and only one surface can be cut. There have been many reports on experimentally examining the conditions for cutting the LCD panel by the scribe-break method. For example, Japanese Patent Application Laid-Open No. Hei 6-102480 describes a method for automatically adjusting a cutter used for scribing.

FIG. 16 is a cross-sectional view showing a center cut portion in the case where four or two LCD panels are formed in a conventional LCD panel manufacturing process. In the figure, 3
a is a main seal material, 3b is a dummy seal which is finally discarded, 4a is a cut which is cut first, 4b, 4c and 4d are cuts which are cut second, third and fourth respectively. , 6 are the parts to be discarded after cutting,
Reference numeral 7 denotes a spacer, and reference numeral 8 denotes a break load. In this case, parameters that affect the cutting performance include a cutting depth, a cutting position, a seal position, a break position, and a break load. Conventionally, by repeating trial and error with changing these parameters,
The conditions are set empirically and the cuts 4a, 4b, 4c, 4
Cutting was performed in the order of d.

[0004]

However, due to the recent trend of larger LCD panels, the notches 4a
When the notch 4a is cut, the gap between the notch 4a and the notch 4a becomes narrow, and cracks do not grow at the notch 4a, and cracks in an abnormal direction grow at the notch 4b. In the case of the process conditions shown in FIG. 16, there was a problem that about 3% of defects occurred. However, with the conventional method of determining process conditions by trial and error through experiments, the optimal conditions and limit conditions are not clear, and a large number of experiments are required when evaluating cutability based on the defect rate, which is important in the process. Therefore, it was impossible to determine the optimum conditions by experiment.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has been made by constructing a numerical analysis model capable of simulating cutting conditions by a scribe-break method in a manufacturing process of a liquid crystal display panel. ,
An object of the present invention is to quickly and inexpensively determine cutting conditions and clarify optimum conditions and limit conditions.

[0006]

According to a method of setting cutting conditions for a liquid crystal display panel according to the present invention, a sealing material is formed on an outer edge portion between a display driving substrate and a counter substrate, and the sealing material is formed by the two substrates and the sealing material. In a manufacturing process of a liquid crystal display panel in which a spacer and a liquid crystal are arranged in a space to be formed, a cutting condition setting method for cutting only one side of any two bonded substrates by a scribe-break method, Create a finite element model of the LCD panel,
The process of inputting the mechanical properties, boundary conditions, and load conditions of the glass substrate, spacer, seal material, etc., which are the constituent materials of the liquid crystal display panel, and using a finite element model to finitely deform the liquid crystal display panel due to the break load Analyzing using the element method to calculate the nodal displacement of the scribe surface;
The cutting property of the liquid crystal display panel is set by predicting the cutting property of the liquid crystal display panel from the stress intensity factor of the scribe tip derived from the nodal displacement and performing the programming of the scribe device and the breaking device.

Further, as a method of creating a finite element model,
The glass substrate and the sealing material are modeled by two-dimensional plane distortion elements, and the spacers are modeled by one-dimensional rod elements. Also,
The elastic modulus and the Poisson's ratio are used as the mechanical characteristic values of the constituent materials. Further, the stress intensity factor is derived using the direct displacement method.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a flowchart showing a method of setting cutting conditions for an LCD panel according to the first embodiment of the present invention, and FIG. 2 is a cross-sectional view showing a central cutting portion when the LCD panel is trimmed in four or two. In the figure, reference numeral 2 denotes a glass substrate constituting a display drive substrate or a counter substrate, etc., 3a a main seal material, 3b a dummy seal which is a seal material finally discarded, 4a a cut which is cut first, 4b, Reference numerals 4c and 4d denote cuts which are cut second, third and fourth, respectively, 6 denotes a portion to be discarded after cutting, and 7 denotes a spacer. In the LCD panel, a sealing material is formed at an outer edge between a display driving substrate and a counter substrate, and a spacer 7 and a liquid crystal (not shown) are formed in a space formed by the two glass substrates 2 and the sealing material.
In the present embodiment, the cutting conditions for cutting only one side of the two bonded glass substrates 2 by the scribe-break method are determined quickly and at low cost by numerical analysis. And clarify the optimum conditions and the limit conditions. In this embodiment, the interval between the cuts 4a and 4b is 3 mm, 4 mm, and 5 m.
The result of evaluating the cutting property when changing to m is shown.

Hereinafter, a method of setting cutting conditions for an LCD panel according to the present embodiment will be described with reference to FIG. First, in step S2, a finite element model of the LCD panel is created. FIG. 3 is a diagram showing the concept of a model based on the finite element method in the present embodiment. In the figure, reference numeral 9 denotes an analysis area, 10 denotes a finite element, and 11 denotes a node. The finite element method approximates an object with infinite degrees of freedom to deformation as a set of elements (finite elements) with finite degrees of freedom,
This is a method for solving a system of linear equations that is established as a set of these elements. The finite element method includes structural mechanics,
The present invention is also applicable to phenomena described by partial differential equations, such as fluid dynamics, heat conduction, and electromagnetism. Elements vary from one-dimensional elements to three-dimensional elements. The glass substrate 2 and the sealing materials 3a and 3b can be modeled by, for example, a two-dimensional plane distortion element, and the spacer 7 can be modeled by, for example, a one-dimensional bar element. FIG. 4A is a diagram illustrating an example of the finite element model according to the present embodiment, and FIG. 4B is an enlarged view of a portion A in the figure. The notch tips 4a and 4b show a remarkable stress concentration, and therefore have a detailed element division degree.
The surfaces of the cuts 4a and 4b are double nodes.

[0010] Beads are present as spacers 7 between the two glass substrates 2 in order to keep the gap constant. L
In the cutting process of the CD panel, the glass substrate 2
Is transmitted to the lower glass substrate 2 by the spacer 7 and the sealing materials 3a and 3b, the beads for the spacer 7 also need to be modeled. Spherical beads can be modeled, for example, with rod elements capable of transmitting axial axial and shear forces. When using a bar element having a square cross section, its cross-sectional area is defined to be equal to the sum of the projected areas of the beads. If the radius of the bead and r, as shown in FIG. 5, the projected area S is expressed by ^{S = 4πr 3/3 ··· (} 1). In FIG. 5, 12 is a spherical bead for the spacer 7, and 13 is a rod element. This is the cross-sectional area of the rod element a
^Since a is equal to ² , a is as follows: a = 2r (πr / 3) ^1/2 (2) Assuming that the abundance ratio of the beads is F and the substrate length of the LCD to be cut is L, the beads are arranged in the LF. Therefore, the bar element cross-sectional area in the width direction in the case of the plane strain model is aLF. When this is replaced with a square, the final side length h of the bar element is h = [2rLF (πr / 3) ^1/2 ] ^1/2 ... (3)

Next, in step S3, first, an elastic modulus and a Poisson's ratio are input as material constants, that is, mechanical property values of constituent materials. The values of the spacer bead material are used for the elastic modulus and Poisson's ratio of the spacer. Since beads having a higher elastic modulus than the sealing material are mixed in the sealing material at a ratio of F, it is necessary to consider the presence of the beads also in the mechanical characteristics of the sealing material. Therefore, the equivalent elastic modulus E ′ obtained by applying the compound rule is defined as the elastic modulus of the sealing material. The compound rule is expressed as follows: E ′ = E _seal × (1-F) + E _beads × F (4) where the elastic modulus of the sealing material and the elastic modulus of the beads are E _seal and E _beads , respectively. . The Poisson's ratio uses the value of the sealing material. For the glass substrate 2, the elastic modulus and Poisson's ratio of the glass are input. The boundary condition restricts the displacement in the Z direction at both ends of the model in the case of the central portion of the substrate. Also, as the load condition,
The load applied by the breaking device is applied to a node corresponding to the break position.

Subsequently, in step S4, using the finite element model created in the above step, the deformation of the LCD panel due to the break load is analyzed using the finite element method.
Calculate the nodal displacement of the scribe surface. The analysis is, for example, M
It can be executed using a general-purpose structural analysis program such as SC / NASTRAN, and the calculated nodal displacement is used for deriving the stress intensity factor in the next step. FIG. 6A is a diagram illustrating an example of the result of the finite element analysis in the present embodiment, and FIG. 6B is an enlarged view of a portion B in the diagram. Bending deformation occurs in the two glass substrates, and the cut surfaces are open.

Next, in step S5, the above step S
From the nodal displacement obtained in step 4, scribe (cut 4a,
4b) Deriving the stress intensity factors K ₁ and K ₂ at the tip. As shown in FIG. 7, the deformation modes of the cracks in the cuts 4a and 4b are an opening type (mode 1), an in-plane shear type (mode 2),
It can be classified as an out-of-plane shear type (mode 3), and the stress intensity factors K ₁ , K ₂ , and K ₃ for each mode can be derived from the results of the finite element method analysis using, for example, the direct displacement method. In the case of the direct displacement method, the relationship between the relative displacement of the nodes on the crack surface and the stress intensity factor is expressed by the following equation. Here, d: distance from crack tip, u, v: displacement in x and y directions on crack surface, G: transverse shear modulus, p: Poisson's ratio, k: 3-4p. K ₁ = [2G (2π) ^1/2 / (k + 1) d ^1/2 ] v (5) K ₂ = [2G (2π) ^1/2 / (k + 1) d ^1/2 ] u ··· (6) In the scribe-break process of the LCD panel, since out-of-plane shear deformation (mode 3) can be neglected, attention is paid to the stress intensity factors K ₁ and K ₂ of mode 1 and mode 2, and the cutting direction and cutting Presence or absence is predicted and evaluated (step S6).
Further, in the cutting step of the LCD panel, because the cracks progress and the glass substrate is divided by the deformation mode type 1, whether the cut is evaluated by K _1, as mode type 2 variant is small, i.e., K ₂ is The smaller the crack, the more the crack grows straight in the glass thickness direction, so that a good cut can be obtained. If cutting is possible, the process conditions are set in step S7, and the scribe device and the break device are programmed in step S8.

FIG. 8 is a diagram showing the relationship between the intervals between the cuts 4a and 4b and K ₁ and K ₂ obtained in the present embodiment. If the cut interval is short, because high is K ₁ towards the 4b side cuts, it develops cracks due to mode 1 (i.e. glass is divided) likely is given,
The cut 4b is predicted. The K ₂ of the cut 4a is almost 0, but the K ₂ of the cut 4b shows a higher value as the cut interval is shorter.
On the b side, the propagation behavior of a crack in which mode 1 and mode 2 are mixed is predicted. From the above, the cut interval is 2 mm,
The condition of 3 mm indicates that crack growth (glass division) occurs in an abnormal direction on the side of the cut 4b, and it can be predicted that good glass division is impossible. Also,
It can also be expected that the critical cutting interval under this condition is about 3.5 mm. Note that the above change in the cutting property is consistent with the experimental result, and the validity of the prediction of the cutting property of the LCD panel in the present embodiment was confirmed.

Embodiment 2 FIG. 9 is a cross-sectional view showing a center cut portion in a case where four or two LCD panels are chamfered in the second embodiment of the present invention. In the figure, 8 indicates a break load, 14 indicates the interval between the cuts 4a and 4b, and 15 indicates the distance of the break position from the center 33 of the sealing members 3a and 3b. In the drawings, the same or corresponding parts have the same reference characters allotted, and description thereof will not be repeated. In the present embodiment, an example in which the cutting conditions are improved using the method for setting the cutting conditions of the LCD panel according to the first embodiment will be described. Figure 10 is a diagram illustrating the present embodiment, the distance 15, notches 4a from the center 33 of the break location, in the case of changing the spacing 14 of 4b, cuts 4a, the mode 1 stress intensity factor K ₁ of the 4b portion It is. From FIG.
The greater the distance 15 from the break position of the center 33, the smaller the K ₁ cut 4b side, the difference between K ₁ cuts 4a side is smaller. Therefore,
When the position of the break load 8 is set on the side of the seal material 3a, it can be predicted that the cut 4a is cut more favorably.

Embodiment 3 FIG. 11 is a cross-sectional view showing a center cut portion in the case where LCD panels are chamfered in four or two in Embodiment 3 of the present invention. In the figure, reference numeral 16 denotes the distance of the cut 4a from the center 33 of the sealing materials 3a, 3b. In the drawings, the same or corresponding parts have the same reference characters allotted, and description thereof will not be repeated. In the present embodiment, an example in which the cutting conditions are improved using the method for setting the cutting conditions of the LCD panel according to the first embodiment will be described. FIG. 12 shows the cut 4 when the distance 15 from the center 33 of the break position and the distance 16 from the center 33 of the cut 4a are changed in the present embodiment.
a, illustrates a mode 1 the stress intensity factor K ₁ of the 4b portion. From FIG. 12, as the distance 15 from the center 33 of the break position increases and the distance 16 of the cut 4a from the center 33 increases, the difference between K ₁ on the cut 4b side and K ₁ on the cut 4a side decreases. ing. Therefore, the position of the break load 8 is changed to the seal material 3a.
If the cut 4a is set to the side and the cut 4a is set to the sealing material 3a side, it can be predicted that the cut of the cut 4a is good.

Embodiment 4 FIG. 13 is a cross-sectional view showing a center cut portion in a case where four or two LCD panels are chamfered in the fourth embodiment of the present invention. In the figure, reference numeral 17 denotes the distance of the sealing material 3b from the center 33 of the sealing materials 3a and 3b. In the drawings, the same or corresponding parts have the same reference characters allotted, and description thereof will not be repeated. In the present embodiment, an example in which the cutting conditions are improved using the method for setting the cutting conditions of the LCD panel according to the first embodiment will be described. FIG. 14 shows a cut 4 when the distance 15 from the center 33 of the break position and the distance 17 from the center 33 of the sealing material 3b are changed in the present embodiment.
a, illustrates a mode 1 the stress intensity factor K ₁ of the 4b portion. From Figure 14, the sealing member 3b greater the distance 17 from the center 33, i.e. enough to move the sealing member 3b notches 4b side, the higher the better cuts 4a side of K _1, that excellent cutting can be obtained Can be predicted.

[0018]

As described above, according to the present invention, a finite element model of a liquid crystal display panel is created, and deformation of the liquid crystal display panel due to a break load is analyzed using a finite element method.
Predicts the cutability of the LCD panel from the stress intensity factor at the scribe tip derived from the nodal displacement of the scribe surface,
Since the scribing device and the breaking device are programmed, the cutting condition can be determined quickly and at low cost, and the optimum condition and the limit condition can be clarified.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating a method for setting an LCD panel cutting condition according to a first embodiment of the present invention;

FIG. 2 is a cross-sectional view showing a center cut portion in the case where four or two LCD panels are chamfered in the first embodiment of the present invention.

FIG. 3 is a diagram illustrating a concept of a model based on a finite element method according to the first embodiment of the present invention.

FIG. 4 is a diagram showing an example of a finite element model of an LCD panel according to Embodiment 1 of the present invention.

FIG. 5 is a diagram showing a concept of modeling a spherical bead with a rod element according to the first embodiment of the present invention.

FIG. 6 is a diagram showing an example of a finite element method analysis result according to the first embodiment of the present invention.

FIG. 7 is a view showing three deformation modes of a crack in the first embodiment of the present invention.

FIG. 8 is a diagram illustrating a relationship between a mode 1 and mode 2 stress intensity factor and a cut interval according to the first embodiment of the present invention.

FIG. 9 is a cross-sectional view showing a center cut portion in a case where four or two LCD panels are chamfered in the second embodiment of the present invention.

FIG. 10 is a diagram showing a relationship between a mode 1 stress intensity factor, a distance between cuts 4a and 4b, and a distance from a center of a break position according to the second embodiment of the present invention.

FIG. 11 is a cross-sectional view showing a center cut portion in a case where four or two LCD panels are chamfered in the third embodiment of the present invention.

FIG. 12 is a diagram showing a relationship between a mode 1 stress intensity factor and a distance from a center of a notch 4a and a break position according to the third embodiment of the present invention.

FIG. 13 is a cross-sectional view showing a center cut portion when LCD panels are chamfered in four or two in Embodiment 4 of the present invention.

FIG. 14 is a diagram illustrating a relationship between a mode 1 stress intensity factor and a distance from a center of a sealing material 3b and a break position according to the fourth embodiment of the present invention.

FIG. 15 is a schematic view showing a state of cutting a glass substrate by a scribe-break method.

FIG. 16 shows a conventional LCD panel manufacturing process.
It is sectional drawing which shows the center cutting part at the time of four or two LCD panel trimming.

[Explanation of symbols]

1 cutter, 2 glass substrate, 3 sealing material, 3a
Main seal material, 3b dummy seal, 4 cuts,
5 squeegee, 7 spacer, 8 break load, 9
Analysis area, 10 finite elements, 11 nodes, 12 beads for spacer, 13 rod elements.

Claims (4)

[Claims] 2. A liquid crystal display panel comprising: a sealing material formed at an outer edge between a display driving substrate and a counter substrate; and a spacer and a liquid crystal arranged in a space formed by the two substrates and the sealing material. In the step, there is provided a cutting condition setting method for cutting only one side of the two bonded substrates by a scribe-break method, wherein a finite element model of the liquid crystal display panel is created, A step of inputting mechanical property values, boundary conditions, and load conditions of glass substrates, spacers, sealing materials, and the like, which are constituent materials, and using the finite element model to deform the liquid crystal display panel due to a break load using a finite element method. Analyzing and calculating the nodal displacement of the scribe surface, the above liquid crystal display from the stress intensity factor at the scribe tip derived from the nodal displacement A method for setting a cutting condition of a liquid crystal display panel, comprising a step of predicting a cutting property of a panel and programming a scribing device and a breaking device. 2. The liquid crystal display panel according to claim 1, wherein the finite element model is created by modeling the glass substrate and the sealing material with a two-dimensional plane strain element and the spacer with a one-dimensional rod element. How to set cutting conditions. 3. The method for setting cutting conditions for a liquid crystal display panel according to claim 1, wherein an elastic modulus and a Poisson's ratio are used as the mechanical property values of the constituent material. 4. The method according to claim 1, wherein the stress intensity factor is derived by using a direct displacement method.