JP2004125833A - Liquid crystal display element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To satisfy a minimum essential overlap width between a panel side lead electrode and a substrate side connection electrode opposite to each other as well as a minimum essential spacing between the panel side lead electrode and the substrate side connection electrode adjacent to each other in a liquid crystal display element using fine-pitch electrodes. <P>SOLUTION: In the liquid crystal display element constructed by electrically and mechanically connecting the panel side lead electrodes 13 formed on the terminal part 11a of a liquid crystal panel and the substrate side connection electrodes 21 formed on the electrode connection part 20a of a flexible substrate via a specified sticking means, the liquid crystal display element is characterized by specifying the optimized width wO of the panel side lead electrode 13 with a formula (1), p+us-gs-t, provided that an electrode width of the substrate side connection electrode 21, a pitch of the panel side lead electrodes 13 and the substrate side connection electrodes 21, the minimum essential overlap width between the panel side lead electrode 13 and the substrate side connection electrode 21 opposite to each other to ensure specified conductive quality, and the minimum essential spacing between the panel side lead electrode 13 and the substrate side connection electrode 21 adjacent to each other to ensure specified insulation quality are represented by t, p, us and gs respectively. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a liquid crystal display device in which a flexible substrate such as a TCP is connected to a liquid crystal panel. More specifically, the present invention reduces a connection failure due to a displacement between a panel-side lead electrode and a substrate-side connection electrode, The present invention relates to a technology that allows the amount of deviation to be easily determined visually.
[0002]
[Prior art]
One of the steps of assembling a liquid crystal display element (liquid crystal module) includes a step of connecting a liquid crystal driving circuit board to a liquid crystal panel. An example of the connection process will be described with reference to FIGS.
[0003]
The liquid crystal panel 10 is formed by pressure-bonding a pair of transparent electrode substrates 11 and 12 via a peripheral sealing material (not shown), and at least one of the transparent electrode substrates 11 has a terminal portion 11a that projects the substrate 11 to the side. Is provided. As shown in FIG. 8, a large number of lead electrodes 13 connected to the transparent electrodes in the panel are formed in a stripe shape (strip shape) on the panel side terminal portion 11a.
[0004]
For example, a TCP (tape carrier package) 20 as a liquid crystal drive circuit board is connected to the panel side terminal portion 11a. The TCP 20 has a liquid crystal driving IC (or LSI) chip 22 mounted on a flexible substrate on which a wiring pattern is formed.
[0005]
On both sides of the IC chip mounting portion (both ends of the substrate), electrode connection portions for signal output and signal input are provided. In FIG. 8, the electrode connection portions are connected to the panel side terminal portion 11a. 1 shows only the electrode connection portion 20a on the signal output side. A large number of connection electrodes 21 are formed in a stripe shape (strip shape) on the electrode connection portion 20a, similarly to the panel side terminal portion 11a.
[0006]
For connection of the TCP 20 to the panel side terminal portion 11a, a thermosetting anisotropic conductive resin or an ultraviolet-curing anisotropic conductive resin is used in many cases. Here, an anisotropic conductive film (ACF) is used. 31 shows an example in which 31 is used.
[0007]
The anisotropic conductive film 31 is a film in which conductive particles are dispersed in, for example, a thermosetting resin film. As shown in FIG. By pressing, the conductive material exhibits a unidirectional conductivity and establishes conduction between the lead electrode 13 and the connection electrode 21.
[0008]
When the lead electrode 13 and the connection electrode 21 are connected, a displacement often occurs between the lead electrode 13 and the connection electrode 21 due to the positioning accuracy of the positioning device, the dimensional tolerance of the liquid crystal panel 10 and the TCP 20, and the like. . FIG. 9 shows a state in which the deviation has occurred.
[0009]
Here, assuming that the lead electrode 13a and the connection electrode 21a are opposing electrodes and the adjacent lead electrode 13b and the connection electrode 21b are opposing electrodes, in order to obtain a good electrical connection state, the following two conditions are required. Is a necessary condition.
{Circle around (1)} The overlapping width us of each of the counter electrodes 13 and 21 is equal to or larger than the width required to secure a predetermined conduction quality.
(2) The separation distance gs between the adjacent board-side connection electrode 21a and the panel-side lead electrode 13b is equal to or longer than the distance required to ensure a predetermined insulation quality.
[0010]
In the actual assembling process, this deviation management must be performed easily and in a short time. Therefore, as a general method, for example, the panel-side lead is visually observed through a microscope instead of the absolute value management of the shift amount (measurement of the core-to-core distance x between the panel-side lead electrode 13 and the board-side connection electrode 21). The protrusion amount a of the substrate-side connection electrode 21 is observed with reference to the electrode 13, and relative value management is performed so that the ratio of the protrusion amount a to the width of the substrate-side connection electrode 21 is, for example, 1/3. I have.
[0011]
[Problems to be solved by the invention]
However, with the recent trend toward finer electrode pitches, the following problems have newly arisen. First, depending on the relationship between the width of the panel-side lead electrode 13 and the width of the substrate-side connection electrode 21, even with a slight deviation, the overlapping width us of the above item (1) and the separation gs of the above item (2) can be obtained. Incompatibilities may result in poor connections.
[0012]
Second, since both the electrode width and the electrode interval become narrower with the fine pitch, one electrode (for example, the panel-side lead electrode 13) and the other electrode are visually observed through a microscope as described above. It becomes difficult to determine the quality by observing the protruding ratio of the (for example, the substrate-side connection electrode 21).
[0013]
Therefore, the first problem of the present invention is that even if a displacement occurs due to the positioning accuracy capability of the positioning device, the dimensional tolerance of the liquid crystal panel and the flexible substrate, etc., the overlapping width us of (1) and the above (1) The object of the present invention is to make it possible to satisfy both the separation interval gs of 2).
Further, a second object of the present invention is to make it possible to judge the quality of a shift between a panel-side lead electrode and a board-side connection electrode by visual observation through a microscope without reducing productivity even at a fine pitch. Is to do.
[0014]
[Means for Solving the Problems]
In order to solve the first problem, the present invention is directed to a liquid crystal panel having a plurality of lead electrodes having terminal portions formed in parallel with each other at a constant pitch, and forming the lead electrodes at the same pitch as the lead electrodes. A liquid crystal display device comprising: a flexible substrate having a plurality of connection electrodes, wherein the panel-side lead electrode and the substrate-side connection electrode face each other and are electrically and mechanically connected via a predetermined bonding means. , The electrode width of the substrate-side connection electrode is t, the pitch of the panel-side lead electrode and the substrate-side connection electrode is p, and a predetermined conduction quality between the opposing panel-side lead electrode and the substrate-side connection electrode. In order to ensure a predetermined insulation quality between the adjacent panel-side lead electrode and the substrate-side connection electrode, the minimum required overlap width is us. The separation interval as gs, the optimum width wO of the panel-side lead electrode, the following equation (1)
wO = p + us-gs-t Equation (1)
It is characterized by the following.
[0015]
Further, in order to solve the second problem, the present invention provides an inspection for any inspection which has an electrical function with an interval of the pitch p on the outermost sides of the panel-side lead electrode and the substrate-side connection electrode. While the test pattern on the substrate side is formed to have the same width as the connection electrode on the substrate side, the electrode width wS of the test pattern on the panel side is expressed by the following equation (2).
wS = t + p-us-gs (2)
It is characterized by the following.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, the present invention will be described in more detail with reference to FIGS. The liquid crystal display element of the present invention is a liquid crystal display element in which, for example, a TCP 20 as a flexible substrate is connected to the terminal portion 11a of the liquid crystal panel 10, as in the conventional example described with reference to FIGS. Therefore, the same reference numerals are used for the components which may be regarded as the same as or the same as those of the conventional example described above.
[0017]
First, FIG. 1 shows a state in which the panel-side lead electrode 13 and the substrate-side connection electrode 21 are aligned in an ideal relationship with no displacement. In this example, the pitch p (the distance between the cores of the electrodes) between the panel-side lead electrodes 13 and the substrate-side connection electrodes 21 is 60 μm, the electrode width w of the panel-side lead electrodes 13 is 35 μm, and the electrode of the substrate-side connection electrodes 21. The width t is 27 μm. In the following description, suffixes a and b are added only when describing adjacent electrodes, and only the reference numerals 13 and 21 are used for the opposing electrodes.
[0018]
In the relationship between the electrode widths t = 27 μm, w = 35 μm, and the pitch p = 60 μm, it is necessary to obtain a predetermined conduction quality between the opposing panel-side lead electrode 13 and substrate-side connection electrode 21. The minimum width, that is, the overlap width us of (1) is 15 μm (us ≧ 15 μm).
[0019]
In addition, the minimum distance required to obtain a predetermined electrical insulation quality between the adjacent substrate-side connection electrode 21a and panel-side lead electrode 13b, that is, the separation distance gs of the above (2) is 20 μm. (Gs ≧ 20 μm). Assuming that the positioning accuracy of the positioning device is xm, xm is ± 8 μm in the current equipment.
[0020]
FIG. 2 shows a state in which the board-side electrode connection portion 20a is shifted to the right with respect to the panel-side terminal portion 11a, and the overlap width us of the opposing panel-side lead electrode 13 and board-side connection electrode 21 is 15 μm. Further, in FIG. 3, the board-side electrode connection portion 20a is shifted rightward with respect to the panel-side terminal portion 11a, and the separation interval gs between the adjacent board-side connection electrode 21a and the panel-side lead electrode 13b is set to 20 μm. Indicates the status.
[0021]
In FIG. 2, when the maximum displacement (distance between the electrode core and the core) between the panel-side lead electrode 13 and the substrate-side connection electrode 21 when the overlap width us of (1) is 15 μm is xu, xu Is given by the following equation (3). In this case, xu = 16 μm.
xu = t / 2 + w / 2-us (3)
[0022]
In FIG. 3, when the maximum displacement (distance between the electrode core and the core) between the panel-side lead electrode 13 and the substrate-side connection electrode 21 when the separation distance gs = 20 μm in (2) above is xg. , Xg are represented by the following equation (4). In this example, xg = 9 μm.
xg = pt / 2-w / 2-gs (4)
[0023]
In order to obtain good connection quality, it is necessary to satisfy both the above-mentioned (1), the overlap width us ≧ 15 μm, and the above-mentioned (2), the separation interval gs ≧ 20 μm. The maximum allowable shift amount xO that may be shifted from the electrode 21 is 9 μm (= xg).
[0024]
With respect to this maximum deviation allowable amount xO = 9 μm, the positioning accuracy capability xm of the positioning device is ± 8 μm in the current equipment as described above, and thus the deviation between the panel-side lead electrode 13 and the substrate-side connection electrode 21. It is extremely difficult to keep the amount within 9 μm, and the incidence of connection failure increases. Incidentally, in view of the positioning accuracy capability of the current positioning device, the maximum deviation allowable amount xO needs to be 1.33 times (10.6 μm) or more of xm.
[0025]
Further, as shown in FIG. 3, the protrusion amount a of the board-side connection electrode 21 is 5 μm with respect to the panel-side lead electrode 13 when the maximum allowable displacement xO, which is the maximum displacement xg, is 9 μm. Therefore, according to the above-described relative value management method, when the protruding amount a is t / 5 (= 5.4 μm) of the board-side connection electrode width t, it is a non-defective product when t / 4 (= 6.75 μm). However, it is extremely difficult to accurately determine the difference of 1.35 μm visually through a microscope, and the determination error rate increases.
[0026]
As can be seen from FIGS. 2 and 3, it is necessary to increase the maximum displacement xg between the panel-side lead electrode 13 and the board-side connection electrode 21 defined by the spacing gs in (2) above. In this case, on the other hand, the maximum displacement xu between the panel-side lead electrode 13 and the board-side connection electrode 21 defined by the overlap width us described in (1) is small. Become.
[0027]
Since the maximum deviation allowable amount xO is the smaller value of the maximum positional deviation amounts xg and xu, the maximum positional deviation amount xu that can satisfy the overlapping width us of the above (1) and the above (2) By determining the electrode width w of the panel-side lead electrode 13 so that the maximum positional deviation amount xg that can satisfy the separation interval gs of ▼ becomes equal, the maximum deviation allowable amount xO can be maximized.
[0028]
Therefore, assuming that the optimum width of the panel-side lead electrode 13 at that time is wO, the optimum width wO is obtained by the following equation (1) derived from the above equations (3) and (4).
xu = xg
t / 2 + w / 2-us = pt / 2-w / 2-gs
From wO = p + us-gs-t (1)
[0029]
In this example, since p = 60 μm, us = 15 μm, gs = 20 μm, and t = 27 μm, the optimum width wO of the panel-side lead electrode 13 is 28 μm. FIG. 4 shows a state where the electrode width of the panel-side lead electrode 13 is wO = 28 μm. The graph of FIG. 5 shows the relationship of the above equations (3) and (4) (the horizontal axis is the electrode width w of the panel-side lead electrode 13 and the vertical axis is the maximum displacement xu, xg).
[0030]
At this time, the maximum allowable displacement xO is 12.5 μm from xO = p−wO / 2−gs−t / 2. As described above, based on the positioning accuracy capability xm (± 8 μm) of the current positioning device, the maximum deviation allowable amount xO may be 10.6 μm (1.33 times xm) or more. xO = 12.5 μm is well compatible with current process capabilities.
[0031]
The present invention includes an inspection pattern DP for displacement inspection, as shown in FIG. 6, in addition to the panel-side lead electrode 13 and the substrate-side connection electrode 21 as counter electrodes. The inspection pattern DP for the displacement inspection is a neutral pattern having no electric function, and is provided at an end of the counter electrode group.
[0032]
Although the shift inspection test pattern DP shown in FIG. 6 is provided at the left end of the counter electrode group, the shift inspection test pattern DP preferably has the same configuration and is provided at both ends of the counter electrode group. 6A shows a state in which the substrate-side electrode connection portion 20a is shifted to the right with respect to the panel-side terminal portion 11a, and FIG. 6B shows a state in which the substrate-side electrode connection portion is shifted with respect to the panel-side terminal portion 11a. 20a shows a state shifted to the left side.
[0033]
The inspection pattern DP for displacement inspection includes a panel-side inspection pattern 14 formed on the terminal portion 11a side of the liquid crystal panel and a substrate-side inspection pattern 22 formed on the electrode connection portion 20a side of a flexible substrate (for example, TCP). And are included.
[0034]
In this case, the pitch between the panel-side inspection pattern 14 and the panel-side lead electrode 13 adjacent to the inside thereof and the pitch between the substrate-side inspection pattern 22 and the substrate-side connection electrode 21 adjacent to the inside thereof are both 60 μm. And the pitch p of the opposing electrodes 13 and 21 is the same.
[0035]
The width of the board-side inspection pattern 22 is 27 μm, which is the same as the electrode width t of the board-side connection electrode 21, but the width wS of the panel-side inspection pattern 14 is specified by the following equation (2). Assuming that the electrode width of the substrate-side connection electrode 21 is t and the maximum deviation allowable amount is xO,
wS = t + 2 × xO
Here, xO is the value of xu (or xg) when the electrode width of the panel-side lead electrode 13 is the optimum width wO, and xO = (p-gs-us) / 2.
wS = t + p-gs-us (2)
It becomes.
[0036]
In this example, since t = 27 μm, p = 60 μm, gs = 20 μm, and us = 15 μm, the width wS of the panel-side inspection pattern 14 is 52 μm. That is, the width wS of the panel-side inspection pattern 14 is a width obtained by adding the maximum allowable deviation xO to both sides of the electrode width t of the substrate-side connection electrode 21.
[0037]
Therefore, as shown in FIGS. 6A and 6B, if the board-side inspection pattern 22 is within the width wS of the panel-side inspection pattern 14, the connection between the panel-side lead electrode 13 and the board-side connection electrode 21 is made. It can be determined that the connection state is good, assuming that the overlap width us of (1) and the separation interval gs of (2) are both satisfied.
[0038]
On the other hand, when the board-side inspection pattern 22 protrudes from the width wS of the panel-side inspection pattern 14, at least one of the overlapping width us of (1) and the separation gs of (2) is satisfied. Since it is not in the state, it can be determined that the connection is poor. In this way, even if each electrode is finely pitched, it is possible to accurately and easily determine the deviation by visual observation through a microscope.
[0039]
In the state shown in FIG. 6B (the state in which the board-side electrode connection portion 20a is shifted to the left with respect to the panel-side terminal portion 11a), the distance B between the panel-side inspection pattern 14 and the adjacent board-side connection electrode 21a. However, even in the case where the separation interval gs in the above (2) occurs, there is no problem because the panel-side inspection pattern 14 is a pattern not involved in the electrical connection.
[0040]
Further, in the drawings of the above embodiment, the cross-sectional shape of the electrode is rectangular, but may be trapezoidal. In the case of this trapezoidal shape, the electrode width and the overlap width may be converted on the upper side of the trapezoid.
[0041]
【The invention's effect】
As described above, according to the present invention, a liquid crystal panel having a terminal portion in which a plurality of lead electrodes are formed in parallel with each other at a constant pitch, and a plurality of connections formed with the same pitch as the lead electrodes 2. A liquid crystal display device comprising: a flexible substrate having electrodes, wherein said panel-side lead electrode and said substrate-side connection electrode face each other and are electrically and mechanically connected via a predetermined bonding means. By specifying the optimum width wO of the panel-side lead electrode by the equation (1) described in (1), even if the displacement occurs due to the positioning accuracy capability of the positioning device, the dimensional tolerance of the liquid crystal panel and the flexible substrate, etc. It is possible to make the overlap width us of (1) and the separation interval gs of (2) compatible.
[0042]
Further, according to the second aspect of the present invention, an inspection pattern for any inspection having an electrical function with an interval of the pitch p is provided on the outermost side of the panel-side lead electrode and the substrate-side connection electrode, While the inspection pattern on the substrate side is formed to have the same width as the connection electrode on the substrate side, the electrode width wS of the inspection pattern on the panel side is set to the width specified by the equation (2), so that the fine pattern can be obtained. Also at the pitch, it is possible to accurately and easily determine the quality of the shift between the panel-side lead electrode and the board-side connection electrode by visual observation through a microscope.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of the present invention, and is a schematic cross-sectional view showing a state in which a panel-side lead electrode and a substrate-side connection electrode are aligned in an ideal relationship with no displacement.
FIG. 2 is an explanatory view of the present invention, and is a schematic cross-sectional view showing a state in which a board-side electrode connection portion is shifted to the right by a minimum required overlap width with respect to a panel-side terminal portion.
FIG. 3 is an explanatory view of the present invention, and is a schematic cross-sectional view showing a state in which a substrate-side electrode connection portion is shifted to the right by a minimum required separation interval with respect to a panel-side terminal portion.
FIG. 4 is an explanatory view of the present invention, and is a schematic cross-sectional view showing a state in which a panel-side lead electrode has an optimum width.
FIG. 5 is an explanatory diagram of the present invention and is a graph showing a relationship between maximum displacements xu and xg between a panel-side lead electrode and a board-side connection electrode.
FIG. 6 is an explanatory view of the present invention and is a schematic cross-sectional view showing an inspection pattern for a shift inspection.
FIG. 7 is a schematic side view illustrating a method of connecting a liquid crystal panel and a liquid crystal drive circuit board.
FIG. 8 is a schematic plan view showing the terminal portion of the liquid crystal panel and the electrode connection portion of the liquid crystal drive circuit board side by side.
FIG. 9 is a schematic cross-sectional view showing a state where the terminal portion and the electrode connection portion in FIG. 8 are shifted.
[Explanation of symbols]
Reference Signs List 10 liquid crystal panel 11a terminal portion 13 panel-side lead electrode 14 panel-side inspection pattern 20 TCP substrate (liquid crystal drive circuit substrate)
20a electrode connection part 21 board side connection electrode 22 board side inspection pattern DP misalignment inspection pattern

Claims (2)

Including a liquid crystal panel having a terminal portion in which a plurality of lead electrodes are formed in parallel with each other at a constant pitch, and a flexible substrate having a plurality of connection electrodes formed to have the same pitch as the lead electrodes, In a liquid crystal display element in which the panel-side lead electrode and the substrate-side connection electrode face each other and are electrically and mechanically connected via a predetermined bonding means,
The electrode width of the substrate side connection electrode is t,
The pitch between the panel-side lead electrode and the board-side connection electrode is p,
In order to ensure a predetermined conduction quality between the opposing panel-side lead electrode and the substrate-side connection electrode, the minimum required overlap width is us,
An optimal width wO of the panel-side lead electrode is expressed by the following equation, where gs is a minimum spacing required to secure a predetermined insulation quality between the adjacent panel-side lead electrode and the substrate-side connection electrode. (1)
wO = p + us-gs-t Equation (1)
A liquid crystal display device characterized by the following. On the outermost sides of the panel-side lead electrode and the substrate-side connection electrode, there is further provided an inspection pattern for any inspection having an electrical function with an interval of the pitch p, and the inspection pattern on the substrate side is the substrate. The electrode width wS of the test pattern on the panel side is defined by the following equation (2)
wS = t + p-us-gs (2)
The liquid crystal display element according to claim 1, wherein the liquid crystal display element is specified by:

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