JP4144387B2 - Electro-optical device and electronic apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electro-optical device such as a liquid crystal device, and more particularly to an electro-optical device and an electronic apparatus in which circuit elements are mounted on a substrate.
[0002]
[Prior art]
In general, a substrate included in an electro-optical device is provided with a driver IC (integrated circuit) that holds an electro-optical material such as liquid crystal and drives the electro-optical material, and is driven from the driver IC to the electro-optical material. Various signals are displayed by supplying signals. In this type of electro-optical device, a technique using an ACF (anisotropic conductive film), which is a kind of anisotropic conductive adhesive member, is known as one technique for mounting a driver IC on a substrate. Here, the ACF is a film in which conductive fine particles are mixed in a base material such as a thermosetting resin, for example, and when compressed in the thickness direction, it is a material that exhibits conductivity in that direction.
[0003]
FIG. 6 is a diagram showing a peripheral configuration of a region where a driver IC is mounted on a substrate in a conventional electro-optical device. As shown in this figure, on the substrate 810, various signals such as a drive signal output from the driver IC 820 are transmitted together with an input wiring 812 that transmits a control signal and drive power supplied from an external device to the driver IC 820. The output wiring 814 is patterned. The land of each of these wirings 812 and 814 is provided in a region where the driver IC 820 is mounted (hereinafter referred to as “mounting region”), and the driver IC 820 sandwiches the ACF 830 having a slightly larger planar shape than the mounting region. , Mounted on the substrate 810. As a result, the terminal of the driver IC 820 is electrically connected to the land of each of the wirings 812 and 814 via the ACF 830 (see, for example, Patent Document 1).
[0004]
[Patent Document 1]
JP 2001-242799 A (FIG. 9)
[0005]
[Problems to be solved by the invention]
By the way, the lands of the wirings 812 and 814 formed on the substrate 810 are concentrated in the mounting area. Therefore, in the vicinity of the edge of the ACF 830, the adjacent wirings 812 and 814 are close to each other, for example, to about 50 μm. Also, among the plurality of input wirings 812, the input wiring 812p provided on one side thereof is a power line for supplying driving power for driving the electro-optical material, and is a high-level DC voltage of about 10V, for example. Is applied. On the other hand, the output wiring 814p adjacent to the input wiring 812p among the output wirings 814 functions as a signal line, and a signal having a low voltage level is transmitted. Therefore, a potential difference of about 10 V is generated between the input wiring 812p and the output wiring 814p. When a potential difference is generated between the input wiring 812p and the output wiring 814p as described above, a strong electric field is generated in a portion where the distance between them is narrow, that is, in a portion where the edge of the ACF 830 crosses both the wirings 812p and 814p.
[0006]
However, the water adhering to the substrate 810 and the water in the atmosphere tend to aggregate at the edge of the ACF 830. Therefore, when a strong electric field is generated by the wirings 812p and 814p, ion exchange occurs in the moisture attached to the edge of the ACF 170 located in the vicinity thereof, and peripheral impurities are aggregated in the wiring through the moisture. As a result, corrosion (corrosion) occurs in the input wiring 812p and the output wiring 814p due to impurities.
[0007]
SUMMARY An advantage of some aspects of the invention is that it provides an electro-optical device and an electronic apparatus in which no corrosion occurs in a wiring patterned on a substrate.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, an electro-optical device according to the present invention includes a circuit element having a plurality of terminals, a substrate having a mounting region on which the circuit element is mounted , A plurality of wirings that are formed on the substrate and transmit signals for driving the electro-optic material; and the plurality of terminals that are interposed between the plurality of terminals and the plurality of wirings of the circuit element; anda anisotropic conductive adhesive member electrically connecting the plurality of wires, said plurality of wires, a power line for transmitting a direct current supplied from the power supply unit of the external device to the circuit elements, an output line for transmitting a driving signal generated by the circuit element includes an input wiring for transmitting control signals to the circuit elements supplied from the control unit of the external device, at least one of said output lines Is connected to the circuit element on the same side as the side to which the power line of the circuit element is connected, and the input wiring is one of the sides adjacent to the side to which the power line of the circuit element is connected. The wiring connected to the circuit element on the same side as the side to which the power line of the circuit element is connected is connected to the circuit element on the side, and is close to the power line in the vicinity of the boundary of the mounting region. And a second portion that is farther from the power line than the first portion at a point that is farther from the mounting area than a point where the power line is bent. anisotropic conductive adhesive member, so as to cross the second portion of the edge is connected to the circuit elements on the same side as the side where the power lines are connected to the circuit elements of said output wiring lines It characterized disposed on the substrate.
According to such an electro-optical device, since the edge of the anisotropic conductive adhesive member is located in the second portion where the wirings are separated from each other, the level of the electric field acting in the vicinity of the edge can be reduced. Thereby, the ion exchange which arises in the edge of an anisotropic conductive adhesive member is reduced, and generation | occurrence | production of corrosion can be prevented.
[0009]
Here, the substrate preferably holds an electro-optical material. According to this configuration, the electro-optical material and the circuit element can be provided on the same substrate.
[0010]
In a preferred aspect, among the wirings, the first portions are substantially parallel to each other.
Also, the electro-optical device according to the present invention, with a display means in electronic devices such as mobile phones, can be used as a means of modulating the light such as the light valve included in the liquid crystal projector.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. In the following description, a passive matrix liquid crystal device will be described as an example of the electro-optical device according to the present embodiment. The liquid crystal device is mounted on an electronic device such as a mobile phone, and displays various types of information under the control of a main control unit included in the electronic device.
[0012]
FIG. 1 is a cross-sectional view of the liquid crystal device according to the present embodiment. As shown in this figure, the liquid crystal device 100 includes a liquid crystal panel 102 and a backlight unit 104 located on the back side of the liquid crystal panel 102.
Among these, the light source 105 included in the backlight unit 104 is, for example, an LED or the like, and irradiates the side end surface of the plate-shaped light guide plate 106 with light. On the other hand, the light guide plate 106 is a light-transmitting plate member such as a synthetic resin, and uniformly emits light from the light source 105 incident from the side end surface thereof toward the liquid crystal panel 102. The reflection plate 107 provided on the back side of the light guide plate 106 plays a role of reflecting light emitted from the light guide plate 106 to the back side to the observation side. In this embodiment, a transmissive liquid crystal device 100 having a backlight unit 104 will be described as an example of the liquid crystal device 100, but the liquid crystal device 100 is not limited to the backlight unit 104, A so-called reflective structure having a reflective layer that reflects external light such as room illumination light may be used.
[0013]
On the other hand, the liquid crystal panel 102 includes a second substrate 120 and a first substrate 110 having a longer length in the longitudinal direction (Y direction in the drawing) than the second substrate 120. Each of the first substrate 110 and the second substrate 120 is a plate-like member having light transmissivity such as glass, and the both substrates are in a state of being opposed to each other so that one end in the longitudinal direction is aligned. 130 is fixed. For this reason, a part of the first substrate 110 protrudes from the second substrate 120. The sealing material 130 has conductive spacers dispersed therein, and fixes both the substrates 110 and 120 with a substantially constant interval. A liquid crystal 140 is sealed in a space sealed by the sealing material 130.
[0014]
In the first substrate 110, a plurality of strip-shaped segment electrodes 111 are formed on the surface of the liquid crystal 140 side. Each of these segment electrodes 111 extends in the Y direction in the drawing, and is formed of a light-transmitting conductive material such as ITO (Indium Tin Oxide). A portion of the segment electrode 111 that faces the second substrate 120 functions as an electrode, but a portion that does not face the second substrate 120, that is, a portion 112 provided in an overhanging region of the first substrate 110 is a driver IC 150 described later. Functions as wiring for transmitting the data signal output from the electrode portion to the electrode portion. Hereinafter, the portion 112 functioning as a wiring in the segment electrode 111 is referred to as an “output wiring”. An alignment film 118 that defines the alignment state of the liquid crystal 140 is provided on the liquid crystal side surface of the first substrate 110 so as to cover the segment electrode 111. On the other hand, a polarizing plate 119 for polarizing incident light is provided on the back surface of the first substrate 110.
[0015]
A plurality of strip-like common electrodes 121 are formed on the surface of the second substrate 120 on the liquid crystal 140 side. These common electrodes 121 are light-transmitting conductors such as ITO, like the segment electrodes 111, but in a direction intersecting with the direction in which each segment electrode 111 extends (for example, a direction perpendicular to the paper surface of FIG. 1). It is provided so that it may extend. An alignment film 128 is provided on the surface of the second substrate 120 on the liquid crystal 140 side so as to cover the common electrode 121, while a polarizing plate 129 is provided on the surface on the observation side.
[0016]
Under such a configuration, the liquid crystal 140 sandwiched between the first substrate 110 and the second substrate 120 causes a potential difference generated between the segment electrode 111 on the first substrate 110 and the common electrode 121 on the second substrate 120. The orientation state changes in accordance with. In the liquid crystal panel 102, the regions where the segment electrodes 111 and the common electrodes 121 face each other are arranged in a matrix, and the minimum unit of the region in which the orientation change of the liquid crystal 140 occurs substantially corresponds to each region arranged in the matrix. is doing.
[0017]
FIG. 2 is an exploded perspective view showing a part of the liquid crystal panel 102. FIG. 3 is a view showing a protruding portion of the first substrate 110. 1 corresponds to a cross-sectional view taken along line AA ′ in FIG.
As shown in these drawings, a flexible wiring substrate 160 is mounted near one end in the longitudinal direction of the first substrate 110. The flexible wiring board 160 transmits various signals supplied from the main control unit of the electronic device on which the liquid crystal device 100 is mounted and power supplied from the power supply unit of the electronic device to the liquid crystal panel 102. Each of the signal line and the power line included in the flexible wiring board 160 is electrically connected to the input wiring 114 formed on the first board 110.
[0018]
The input wiring 114 is formed by patterning, for example, copper, and an area 150R (hereinafter referred to as “mounting area”) in which the driver IC 150 is mounted in order to transmit various signals and power supplied from the flexible wiring board 160 to the driver IC 150. "). Here, the input wiring 114p provided on one side of the input wiring 114 is a power line, and a voltage of, for example, 10V is applied.
[0019]
The capacitor 180 performs step-up / step-down for driving the liquid crystal 140, and is electrically connected to the step-up / down wiring 116 formed on the first substrate 110. Each of the step-up / down wirings 116 has one end connected to the capacitor 180 and the other end routed to the mounting region 150R of the driver IC 150. A voltage (for example, 10 V) boosted by the capacitor 180 is applied to the step-up / step-down wiring 116 p provided on one side of the step-up / step-down wiring 116.
[0020]
In FIG. 2, a driver IC 150 is a kind of circuit element, and receives a control signal and power from an external device via an input wiring 114, and also receives power from a capacitor 180 via a step-up / down wiring 116, A data signal and a scanning signal for driving the liquid crystal are generated. The driver IC 150 outputs the generated data signal to the output wiring 112, while outputting the scanning signal to the output wiring 113. As shown in FIG. 1, a terminal 152 is provided on one surface of the driver IC 150 casing. The driver IC 150 is mounted on the first substrate 110 so that the surface on which the terminal 152 is provided and the mounting region 150R face each other, which will be described in detail later.
[0021]
The output wirings 112 and 113 have their lands provided in the mounting region 150 </ b> R, and transmit the drive signal output from the driver IC 150 to the segment electrode 111 and the common electrode 121. More specifically, as shown in FIG. 2, of the output wirings 112 and 113, the output wiring 112 led out from the mounting region 150R in the Y direction is integrally formed with the segment electrode 111 as described above (FIG. 2). 1), the data signal output from the driver IC 150 is transmitted to the segment electrode 111.
[0022]
On the other hand, the output wiring 113 led out from the mounting region 150R in the X direction transmits the scanning signal output from the driver IC 150 to the common electrode 121 formed on the second substrate 120. Note that each of the output wiring 113 and the common electrode 121 is electrically connected in a one-to-one correspondence relationship through conductive spacers dispersed in the sealing material 130.
[0023]
As shown in the enlarged view on the right side in FIG. 3, among the output wirings 113, the output wiring 113p provided on the flexible wiring board 160 side is an input wiring 114p that functions as a power line in the vicinity of the boundary of the mounting region 150R. Although it is close to 50 μm, it is separated from the input wiring 114p as it is away from the mounting region 150R. Specifically, each of the output wiring 113p and the input wiring 114p extends in the X direction while being substantially parallel to each other in the vicinity of the boundary of the mounting region 150R, but is an input that is one of the wirings 113p and 114p. The wiring 114p is bent in the Y direction at a point slightly away from the boundary of the mounting region 150R. Therefore, the distance between the output wiring 113p and the input wiring 114p increases as the distance from the bent point of the input wiring 114p increases.
[0024]
On the other hand, as shown in the enlarged view on the left side in FIG. 3, among the output wirings 113, the output wiring 113r provided on the capacitor 180 side has a boosted voltage to which a boosted voltage is applied in the vicinity of the boundary of the mounting region 150R. The wiring 116r is close to 50 μm, but is separated from the step-up / step-down wiring 116r as the distance from the mounting region 150R increases.
[0025]
A driver IC 150 is attached by an ACF 170 to the mounting region 150R where the lands of the input wiring 114, the step-up / step-down wiring 116 and the output wirings 112 and 113 are provided. The ACF 170 is an anisotropic conductive adhesive member in which conductive fine particles such as gold and nickel are dispersed in a base material having thermosetting properties, for example. When compressed in the thickness direction, the ACF 170 is formed on the first substrate 110. The land and the terminal 152 of the driver IC 150 are electrically connected via one particle.
[0026]
Incidentally, a DC voltage of 10V is applied to the input wiring 114p, but a scanning signal having a low voltage (for example, 1V or less) is applied to the output wiring 113p adjacent thereto. Therefore, a high level potential difference is generated between the wirings 113p and 114p. Further, in the vicinity of the boundary of the mounting area 150R of the driver IC 150, the output wiring 113p and the input wiring 114p are close to each other up to 50 μm. As a result, a strong electric field is generated near the portion of the mounting region 150R that crosses the output wiring 113p and the input wiring 114p. Similarly, a strong electric field is also generated in the vicinity of the portion of the boundary of the mounting region 150R that crosses the step-up / down wiring 116r and the output wiring 113r.
Therefore, if the ACF 170 having such a shape that the edge of the ACF 170 crosses the portion where the electric field of these strengths is provided, ion exchange occurs in the moisture adhering to the edge of the ACF 170, causing corrosion in nearby wiring. End up. In particular, as in this embodiment, when a DC voltage is applied to the input wiring 114p and one of the input wiring 114p and the output wiring 113p is always at a higher potential than the other, it acts on the edge of the ACF 170. The direction of the electric field becomes substantially constant, and the problem becomes more prominent.
[0027]
Therefore, in the present embodiment, the planar shape of the ACF 170 is selected so that the edge of the ACF 170 is not located at a portion where an electric field of high strength is generated. More specifically, the ACF 170 is configured such that the edge of the output wiring 113p and the input wiring 114p crosses a portion where both wirings are separated (a portion where the pitch between the wirings is larger than 50 μm). Specifically, the edge of the ACF 170 crosses each of the output wiring 113p and the input wiring 114p at a point where the extending direction of the input wiring 114p is far from the mounting region 150R than the point where the extending direction of the input wiring 114p is bent from the X direction to the Y direction. Yes. Further, the ACF 170 is configured such that the edge of the step-up / step-down wiring 116r and the output wiring 113r crosses a portion where both wirings are separated from each other (a portion where the pitch between the wirings is larger than 50 μm). By selecting the planar shape of the ACF 170 so that the edge of the ACF 170 crosses a portion of the wiring set that is spaced apart from each other for a set of wirings that can cause a high-level potential difference in this manner, The applied electric field becomes a low level. Thereby, ion exchange in the vicinity of the edge of ACF 170 is reduced, and corrosion of the wiring can be prevented.
[0028]
When the ACF 170 having such a shape is sandwiched between the first substrate 110 and the driver IC 170 and is pressed in the thickness direction of the ACF 170 while being heated, as shown in FIG. The terminal 152 of the driver IC 150 and the lands of the output wiring 113, the input wiring 114, and the step-up / down wiring 116 are fixed to the substrate 110.
[0029]
As described above, according to the liquid crystal device 100, the strength of the electric field generated at the edge of the ACF 170 is reduced, so that corrosion of wiring can be prevented.
[0030]
Note that the electro-optical device of the present invention is not limited to the above-described illustrated examples, and various modifications can be made without departing from the scope of the present invention. For example, the liquid crystal panel 102 shown in each of the above embodiments basically has a simple matrix structure, but an active matrix system using an active element (active element) such as a TFT (thin film transistor) or a TFD (thin film diode). It can also be applied to the liquid crystal device.
In the above-described embodiment, an example in which the present invention is applied to a structure in which the driver IC 150 is directly mounted on the liquid crystal panel 102 (so-called COG (Chip On Glass) structure) has been described. Even if the present invention is applied to a structure in which the driver IC 150 is mounted on the wiring board 160 (so-called COF (Chip On Film) structure), or a structure in which the driver IC 150 is mounted on a rigid wiring board (so-called COB (Chip On Board) structure). I do not care. That is, the substrate to which the present invention can be applied is not limited to a substrate for holding an electro-optical material such as liquid crystal, and the present invention is arbitrarily applied as long as it is a substrate on which wiring is provided and a circuit element is mounted. be able to.
[0031]
In the above-described embodiment, the liquid crystal device 100 including the liquid crystal panel 102 is described as an example of the electro-optical device according to the present invention. However, the present invention is not limited to this, and instead of the liquid crystal panel 102. In addition, it can be applied to various electro-optical devices including an electroluminescence panel, in particular, an organic electroluminescence panel, an inorganic electroluminescence panel, a plasma display panel, an FED (field emission display) panel, an electrophoretic display panel, and the like. . The present invention can also be applied to various electro-optical devices such as LED (light emitting diode) display devices, thin cathode ray tubes, small televisions using liquid crystal shutters, and devices using digital micromirror devices (DMD). it can. That is, when the circuit element is mounted on the substrate using the ACF 170 (anisotropic positively conductive adhesive member), the edge of the ACF 170 crosses the portion where the two wires are separated from each other out of the two wires that may cause a potential difference. By providing the ACF 170, wiring corrosion can be prevented.
[0032]
Finally, an electronic apparatus equipped with the liquid crystal device 100 described above will be described.
For example, FIG. 5 is an external view of a mobile phone 300 having the liquid crystal device 100 described above as a display unit. In this figure, a mobile phone 300 includes the liquid crystal device 100 as a display unit for displaying various information such as a telephone number, in addition to a plurality of operation buttons 310, as well as an earpiece 320 and a mouthpiece 330.
In addition to the mobile phone 300, the liquid crystal device 100 (electro-optical device) is used as a display unit of various electronic devices such as a computer, a projector, a digital camera, a movie camera, an in-vehicle device, a copying machine, and an audio device. it can.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a liquid crystal device according to an embodiment of the present invention.
FIG. 2 is an exploded perspective view of a liquid crystal panel included in the liquid crystal device.
FIG. 3 is a plan view showing a peripheral configuration of a driver IC mounting region in the liquid crystal panel. FIG. 4 is a perspective view showing a peripheral configuration of the driver IC in the liquid crystal panel.
FIG. 5 is a diagram showing a mobile phone equipped with the liquid crystal device.
FIG. 6 is a perspective view showing a peripheral configuration of a driver IC in a conventional liquid crystal panel.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 100 Liquid crystal device, 102 Liquid crystal panel, 110 1st board | substrate, 112,113,113p, 113r Output wiring, 114,114p Input wiring, 116,116r Buck-boost wiring, 120 2nd board | substrate, 150 Driver IC, 152 terminal, 170 ACF 180 capacitors.

Claims (4)

In an electro-optical device having an electro-optical material,
A circuit element having a plurality of terminals;
A substrate having a mounting area on which the circuit element is mounted ;
A plurality of wirings that are formed on the substrate and transmit signals for driving the electro-optic material;
An anisotropic conductive adhesive member interposed between the plurality of terminals of the circuit element and the plurality of wirings to electrically connect the plurality of terminals and the plurality of wirings ;
Wherein the plurality of wires, a power line for transmitting a direct current supplied from the power supply unit of the external device to the circuit elements, and an output line for transmitting a driving signal generated by the circuit elements, the control unit of the external device An input wiring for transmitting a supplied control signal to the circuit element ,
At least a part of the output wiring is connected to the circuit element on the same side as the side to which the power line of the circuit element is connected, and the input wiring is a side on the side to which the power line of the circuit element is connected. Is connected to the circuit element on one side of the sides adjacent to each other,
The wiring connected to the circuit element on the same side of the output wiring as the side to which the power line of the circuit element is connected includes a first portion adjacent to the power line in the vicinity of the boundary of the mounting region, and the power line. A second portion that is further away from the power line than the first portion at a point that is farther from the mounting area than a point where the
The anisotropic conductive adhesive member has an edge crossing the second portion of the wiring connected to the circuit element on the same side as the side of the output wiring to which the power line of the circuit element is connected . An electro-optical device arranged on the substrate. The electro-optical device according to claim 1, wherein the substrate holds an electro-optical material. The electro-optical device according to claim 1, wherein the first portions of the wirings are substantially parallel to each other. An electronic apparatus comprising the electro-optical device according to any one of claims 1 to 3.

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