Source: http://www.google.com/patents/US6781109?dq=7,346,545
Timestamp: 2017-10-23 08:15:18
Document Index: 711040441

Matched Legal Cases: ['art 13', 'art 13', 'arts 13', 'arts 13', 'art 13', 'art 13', 'art 13', 'art 13', 'art 13']

Patent US6781109 - Active matrix substrate having transparent connecting terminals - Google Patents
An active-matrix substrate is provided with electrode wires disposed in a lattice form, a plurality of switching elements disposed respectively at intersections of the electrode wires, and connecting terminals for connecting the electrode wires to the outside, the electrode wires include metal electrodes,...http://www.google.com/patents/US6781109?utm_source=gb-gplus-sharePatent US6781109 - Active matrix substrate having transparent connecting terminals
Publication number US6781109 B2
Application number US 10/265,408
Also published as US6518557, US20030102424
Publication number 10265408, 265408, US 6781109 B2, US 6781109B2, US-B2-6781109, US6781109 B2, US6781109B2
Inventors Yoshihiro Izumi, Osamu Teranuma
Patent Citations (9), Non-Patent Citations (3), Referenced by (15), Classifications (26), Legal Events (3)
Active matrix substrate having transparent connecting terminals
US 6781109 B2
electrode wires made of metal disposed in a lattice form,
a plurality of switching elements in communication with said metal electrode wires,
connecting terminals for connecting said metal electrode wires to an outside,
wherein at least parts of said connecting terminals have a property of transmitting light, and wherein said metal electrode wires are substantially non-light-transmitting; and
wherein at least one of said connecting terminals includes a non-transmissive portion for shielding or blocking light, and said non-transmissive portion comprises a structure in which a transparent conductive film is stacked on a metallic film.
2. The active-matrix substrate as defined in claim 1, wherein said connecting terminal is made of a material having a property of transmitting light.
wherein at least one of said connecting terminals includes a metal terminal pail and openings penetrating the metal terminal part in a thickness direction.
4. The active-matrix substrate as defined in claim 3, wherein a metal part of said metal terminal part has a width between 2 μm and 50 μm.
5. A The active-matrix substrate as defined in claim 3, wherein said openings are formed in a lattice form.
6. The active-matrix substrate as defined in claim 3, wherein said connecting terminal has a laminated structure consisting of a metal and a transparent conductive oxide film.
This application is a continuation of application Ser. No. 09/477,338, filed Jan. 4, 2000, now U.S. Pat. No. 6,518,557 the entire content of which is hereby incorporated by reference in this application.
As shown in FIGS. 6 and 8, the two-dimensional image detector for radiation is provided with an active-matrix substrate 51 having electrode wires (gate electrode group 52 consisting of a plurality of gate electrodes G1, G2, G3, . . . , and Gn and source electrode group 53 consisting of a plurality of source electrodes S1, S2, S3, . . . , and Sn) in an XY matrix form, a TFT (thin film transistor) 54 and a storage capacitor (Cs) 55, on a glass substrate. Moreover, input/output terminals are disposed on ends (not shown) of the active-matrix substrate 51. Furthermore, a photoconductive film 56, a dielectric layer 57, and an upper electrode 58 are formed on virtually the entire surface of the active-matrix substrate 51.
For the photoconductive film 56 (amorphous semiconductor layer), a semiconductive material is used to generate electric charge (electron-hole pair) by exposure to radiation such as an X-ray. According to the aforementioned literatures, amorphous selenium (a-Se) is used as a semiconductor material, which has high dark resistance and favorable photoconductivity and can form a large film by evaporation. The photoconductive film (a-Se) 56 is formed with a thickness of 300-600 μm by using a vacuum evaporation method.
Further, an active-matrix substrate, which is formed in a manufacturing process of a liquid crystal display device, can be applied to the aforementioned active-matrix substrate 51. For example, the active-matrix substrate used for an active matrix liquid crystal display device (AMLCD: Active Matrix LCD) is provided with the TFT made of amorphous silicon (a-Si) or polysilicon (p-Si), an XY matrix electrode, and a storage capacitor. Therefore, only if a few changes are made in arrangement, the active-matrix substrate can be used for the two-dimensional image detector for radiation.
Electric charge (electron-hole pair) is generated in the photoconductive film 56 when the photoconductive film 56 such as an a-Se film is exposed to radiation. As shown FIGS. 6 through 8, the photoconductive film 56 and the storage capacitors (Cs) 55 are electrically connected in series with each other; thus, when voltage is applied between the upper electrode 58 and the Cs electrode 59, electric charge (electron-hole pair) generated in the photoconductive film 56 moves to a positive electrode side and a negative electrode side. As a result, the storage capacitors (Cs) 55 stores electric charge. Further, an electron blocking layer 62 made of a thin insulating layer is formed between the photoconductive film 56 and the storage capacitor (Cs) 55. The electron blocking layer 62 acts as a blocking photodiode for preventing electric charge from being injected from one side.
With the above-mentioned effect, the thin-film transistor (TFT) 54 is turned on in response to input signals of gate electrodes G1, G2, G3, . . . , and Gn so that the electric charge stored in the storage capacitors (Cs) 55 can be applied to the outside from source electrodes S1, S2, S3, . . . , and Sn. The gate electrode group 52 and the source electrode group 53, the TFT 54, the storage capacitors 55, and the like are made in a matrix form; therefore, it is possible to obtain two-dimensional image information of an X-ray by on lines sequentially scanning signals inputted to gate electrodes G1, G2, G3, . . . , and Gn.
ANISOTROPIC CONDUCTIVE BONDING
ADHESIVE KIND OF BINDER TEMPERATURE (° C.) TIME (SECOND)
ANISOTROPIC CONDUCTIVE FILM THERMOSETTING 170 ± 10 20
Hitachi Chemical Co., Ltd. RESIN
ANISOTROPIC CONDUCTIVE FILM THERMOSETTING 220 ± 10 5≦
SONY CHEMICALS CORP. RESIN
According to Table 1, when a conventional thermosetting resin and thermoplastic resin are used for the anisotropic conductive adhesive, a heating operation of (150° C. or more)×(5-30 seconds) is normally necessary in order to obtain adhesion and conductivity by using a thermosetting reaction or a thermoplastic operation of the above resins while pressurizing.
Generally, the a-Se film is formed by evaporation at 60-80° C. or more so as to be amorphous with high dark resistance of about 1012 Ωcm; thus, the a-Se film has proper characteristics for the two-dimensional image detector. However, when a heating operation is performed after the film is formed, the dark resistance decreases to a maximum of about 105 Ωcm. This is because the crystallization of the amorphous a-Se film is developed by heat. Moreover, it has been known that the crystallization of the a-Se film is developed at a relatively low temperature of 60-80° C. as well as at a high temperature.
In the present invention, the anisotropic conductive adhesive, has photo-reactivity (the photoreactive anisotropic conductive adhesive) includes an adhesive (photo-curing adhesive) in which a curing reaction is developed by irradiation of light such as an ultraviolet ray and a visible ray, and an adhesive (photo-assist thermosetting adhesive) in which activation is improved by irradiation of light such as an ultraviolet ray and a visible ray and a curing reaction is developed by a heating operation at a relatively low temperature.
FIG. 11 is an enlarged view showing still another example of the input/output terminals disposed on ends of the active-matrix substrate of the two-dimensional image detector in accordance with one embodiment of the present invention.
Here, the a-Se film 6 is an amorphous semiconductor layer, in which selenium is a main component with a ratio of 50 percents or more by weight. Additionally, as described above, the a-Se film 6 is crystallized in a heating operation at a relatively low temperature of 60-80° C., usually at 70° C. The crystallization is accelerated at the above temperature or more (60-80° C. or more).
As described above, the anisotropic conductive adhesive containing the photo-curing resin is adopted as the bonding part 13 so as to connect the input/output terminals 14 disposed on the active-matrix substrate 1 and the connecting terminals of the TCP substrate 17; hence, it is not necessary to cure the anisotropic conductive adhesive and to increase adhesion by a heating operation. Therefore, unlike the conventional art, the need for a heating operation of (150° C. or more)×(5-30 seconds) can be eliminated. Therefore, when the TCP substrates 17 are connected to the active-matrix substrate 1, on which the a-Se film has been previously formed, it is possible to prevent degradation in a characteristic such as crystallization of the a-Se film 6, namely, high dark resistance, without conducting heat to the a-Se film 6.
When the members are mounted by using a conventional thermosetting anisotropic conductive adhesive containing a thermosetting resin, in a TCP method, a phenomenon is confirmed in which a temperature of the a-Se film rises to 80-100° C. around the image pick-up area, and accordingly, a reduction in dark resistance of the a-Se film is confirmed. However, as described in the present embodiment, when an anisotropic conductive adhesive containing a photo-curing resin is adopted as the bonding part 13, a temperature of the a-Se film does not rise at all, causing no degradation of the above characteristic of the a-Se film.
As shown in FIG. 10, a curing rate of the photo-curing anisotropic conductive adhesive relative to a width L of the wire 42 is measured as follows: the substrate 43, which is provided with the wires 42 made of a material being unable to transmit an ultraviolet ray, is disposed such that a surface where the wires 42 are formed opposes the glass substrate 45 via the photo-curing anisotropic conductive adhesive 44; an ultraviolet ray is emitted to the side end 42 a of the wire 42 at a 45° angle from the back of the surface of the glass substrate 41 where the wire 42 is formed; and a degree of photo-reactivity is found at the evaluation point P based on an absorption spectrum, which is measured by using an FT-IR micro-system (Fourier Transform Infrared Spectrophotometer).
Further, an ultraviolet ray is emitted under the condition of 30 nW/cm2×10 seconds. Each of the glass substrates 41 and 45 is 1.1 mm in thickness. Moreover, as the photo-curing anisotropic conductive adhesive, an epoxy metamorphosed acrylic anisotropic conductive adhesive is adopted, in which 5 μm-diameter resin particles are dispersed. The substrate 43 and the glass substrate 45 are disposed so as to oppose each other at a bonding part such that a gap is 5 μm on a part where the wire 42 is formed; namely, a gap “g” is 5 μm between the glass substrate 45 and the wire 42 disposed on the glass substrate 41 of the substrate 43. Furthermore, an Al (aluminum) wire is used as the wire 42.
L (μm) 10 20 50 100 200
CURING RATE (%) 94 93 91 86 78
Hence, when an ultraviolet ray (light) is emitted from the back of the active-matrix substrate, at least a part of the input/output terminal disposed near the bonding part needs to transmit light in order to sufficiently develop a photo-reactivity (photo-curing reaction) of the anisotropic conductive adhesive. When an ultraviolet ray (light) is emitted from the back of the active-matrix substrate, it is desirable to sufficiently develop a photo-reactivity of the photo-curing (photoreactive) conductive adhesive in accordance with a diffraction effect of the ultraviolet ray (light) to the surface of the input/output terminal.
However, when the input/output terminal 14 is made of ITO, the glass substrate and the ITO obtain absorbing ends for absorbing an ultraviolet ray, at a wavelength of about 350 μm. Therefore, in this case, it is not possible to cure a photo-curing anisotropic conductive adhesive by using an ultraviolet ray having a wavelength shorter than the above absorbing end. Hence, in this case, as a photoreactive resin used for the anisotropic conductive adhesive, it is possible to adopt a resin which reacts to light having a wavelength longer than that of the absorbing end, and preferably a material which is frequently adopted for industrial use and is cured at a wavelength of 365 nm (i-ray ultraviolet ray), or a resin (material) which is cured with light (light such as blue light in a visible area) whose wavelength is longer than 365 nm.
In the same manner, when the input/output terminals 14 are made of a material being able to transmit light, as for the above photoreactive anisotropic conductive adhesive, it is possible to adopt a material being photoreactive to light whose wavelength is determined in accordance with absorption wavelengths of materials forming the input/output terminals 14 and the active-matrix substrate 1, which is disposed on a side where light is emitted.
As described above, when input/output terminals 14 include metal parts (metal terminal parts), adhesion is small between (a) the conductive particles contained in the photo-curing anisotropic conductive adhesive and (b) the metal parts of the input/output terminals 14, it is desirable to maximize areas of metal parts of the input/output terminals 14 around the bonding parts 13. However, in view of a curing property of the photo-curing anisotropic conductive adhesive, it is desirable to maximize opening areas of the openings 18 on the input/output terminals 14 around the bonding parts 13.
Additionally, the present embodiment does not particularly limits the L/S ratio of the openings 18 in each of the input/output terminals 14 and the number of the openings 18 formed in each of the input/output terminals 14. Any other condition can be adopted as long as the bonding part 13 is formed by a photo-curing process.
Furthermore, when the input/output terminals 14 are provided with metal terminal parts, the metal terminal parts can be formed by materials which are different from those of electrode wires such as the gate electrodes 2 and the source electrodes 3. For example, only parts to be the input/output terminals 14 are slated with materials having different resistance values, for example, metal materials having low resistance values, or slated with metal materials having superior adhesion with the conductive particles, or it is possible to adopt a laminated structure in which different metal films are stacked. With this arrangement, for example, it is possible to favorably maintain a bonding strength between the photo-curing anisotropic conductive adhesive and the input/output terminals 14.
As described above, in the case of the input/output terminals 14 being provided with the metal terminal parts, when directivity of light such as an ultraviolet ray is too high and the light is emitted from the back of the active-matrix substrate 1, the light hardly diffracts to the anisotropic conductive adhesive, which is photoreactive and is formed on the metal pattern. Therefore, when the input/output terminals 14 are provided with the metal terminal parts, as for light emitted to the anisotropic conductive adhesive having photo-reactivity (the photoreactive anisotropic conductive adhesive), it is desirable to adopt a light irradiating apparatus (for example, an irradiating apparatus for an ultraviolet ray), in which the directivity is low or irradiation components are large (large radiation angle) in a diagonal direction.
To be specific, firstly, the film-type photo-curing anisotropic conductive adhesive is transferred onto input/output terminals 14 formed on ends of the active-matrix substrate. The transfer requires a heating operation (about 100° C.×several seconds) and a pressurizing operation at 9.8 mPa (10 kgf/cm2). Next, connecting terminals of a TCP substrate 17 are aligned with the input/output terminals 14 formed on ends of the active-matrix substrate 1; namely, the positions of connecting parts are determined. Finally, the heating operation (about 100° C.×several seconds) is performed so as to soften the films constituting the anisotropic conductive adhesive while pressurizing the connecting part of the TCP substrate 17 at a pressure of 9.8 mPa to 29.4 mPa (10 to 30 kgf/cm2), and then, an ultraviolet ray is emitted (integral light amount: 3000 mJ/cm2) thereon so as to cure the anisotropic conductive adhesive.
When the active-matrix substrate 1 is connected to the TCP substrate 17 by using the above method, a heating operation (about 100° C.×several seconds) is necessary for softening the anisotropic conductive adhesive; however, unlike the conventional art, a heating operation of (150° C. or more)×(5 to 30 seconds) is not necessary.
Actually, in a process for softening the film-type anisotropic conductive adhesive serving as the bonding part 13, even when a heating operation of (about 100° C.)×(five minutes) is performed, the heat conducted to the a-Se film 6 is 50° C. or less, so that the above characteristic of the a-Se film 6 is not degraded.
As described in the present embodiment, when a film-type photo-curing anisotropic conductive adhesive is used as a bonding part, a heating operation of (about 100° C.×several seconds) is necessary. However, the bonding part of the present embodiment contains a photo-curing resin as described above, so that a heating operation is not necessary for thermosetting; consequently, it is possible to connect input/output terminals without degradation in a characteristic of an amorphous semiconductor layer.
Further, the usage of the active-matrix substrates described in Embodiments 1 through 3 is not limited to the above two-dimensional image detector but is applicable to an active-matrix substrate used for a liquid crystal display device. In recent years, there has been a growing need for a larger model, higher definition, and lower cost regarding a display device using the active-matrix substrate. Particularly, in order to realize high definition, upon connecting the input/output terminals of the active-matrix substrate (mainly input terminals in a display device) to the outside, high connecting accuracy is required. Hence, in order to lower a heating temperature upon connecting and to prevent thermal expansion of the substrate and the connecting members from causing degradation in positioning accuracy, it is desirable to use a photoreactive anisotropic conductive adhesive, which allows connection with a low-temperature operation.
Furthermore, a drain electrode 23 of the TFT 22 is connected with the pixel electrode 10 via a contact hole (not shown) or the like and is connected with one of electrodes of a storage capacitor (Cs) 24.
Meanwhile, as shown in FIGS. 14 and 15, In an opposing substrate 30, an opposing electrode (opposing common electrode)32 formed by a transparent electrode such as ITO is formed entirely on a transparent insulating substrate (light-transmitting substrate) 31 made of a material such as glass. Furthermore, on both substrates, namely, on the opposing surfaces of the active-matrix substrate 1 and the opposing substrate 30, alignment films (not shown), which are subjected to a uniaxial alignment such as a rubbing operation, are formed. The substrates are bonded to each other with a sealing agent 33. A liquid crystal layer 34 serving as a display (electro-optical medium) is sandwiched between the substrates.
As shown in FIG. 13, the liquid crystal display device with the above construction of the present embodiment is provided with a pixel alignment layer 11 on the active-matrix substrate 1, the pixel alignment layer 11 including the electrodes wires (gate electrodes 2 and source electrodes 3) formed into an XY matrix form (lattice form), the switching element (TFT 22) provided at each of the intersections of the electrode wires, namely, in each pixel, the storage capacitors 24, and the pixel electrodes 10. As described above, around the active-matrix substrate 1, a plurality of the input/output terminals 14, that are identical to the input/output terminals 14 shown in FIG. 3, FIG. 4, FIG. 11, FIG. 12(a) and FIG. 12(b) of Embodiment 1, are disposed so as to serve as connecting terminals connected to the outside, namely, to the external members including the electric member and the electric circuit (external circuit) such as the TCP substrate 17.
In FIG. 13, the driving ICs 15 are connected (mounted) to the input/output terminals 14 disposed on the active-matrix substrate 1, by using TCP method. As described above, the input/output terminals 14 are disposed on ends of the active-matrix substrate 1 to input and output an electron signal to the gate electrodes 2 and the source electrodes 3. With this arrangement, the input/output terminals 14 can input an image signal from the external electric circuit in response to a displayed image. Here, in FIG. 13, the number of the connected TCP substrates 17 is smaller than the actual number for convenience of understanding.
FIG. 14 shows an example of the arrangement (package) in which the bonding part 13 is formed between the active-matrix substrate 1 and the TCP substrate 17, which is described as an external member in Embodiment 1.
In the above arrangement, upon making a connection (TCP connection) between the TCP substrate 17 and the input/output terminals 14 which are disposed on the active-matrix substrate 1, namely, upon forming the bonding part 13, for example, a photo-assist anisotropic conductive adhesive is used as an anisotropic conductive adhesive having photo-reactivity (photoreactive anisotropic conductive adhesive). In the present embodiment as well, the anisotropic conductive adhesive connects the TCP substrates 17 and the input/output terminals 14 by using its adhesion, and the adhesive electrically connects the input/output terminals 14 to the outside by using its anisotropic conductivity.
At least a part for bonding the input/output terminals 14 and the TCP substrates 17 has the property of transmitting light; thus, from the back of the surface on which the input/output terminals 14 of the active-matrix substrate 1 are disposed (formed), it is possible to positively supply enough amount of light to develop the photo-reactivity of the anisotropic conductive adhesive, via the input/output terminals 14, without being interrupted by the input/output terminals 14. With this arrangement, the anisotropic conductive adhesive can be efficiently connected. In this case, when the photo-assist thermosetting adhesive is used as the anisotropic conductive adhesive as described above, a heating operation is performed at a relatively low temperature, for example, at about 100° C. after irradiation of light or simultaneously with irradiation of light, so that the anisotropic conductive adhesive including the photo-curing resin is cured; hence, the bonding part 13 is formed.
Additionally, in Embodiment 4, the photo-assist anisotropic conductive adhesive is used when the input/output terminals 14 disposed (formed) on the active-matrix substrate 1 are electrically connected to the external circuit (external member) such as the TCP substrates 17. If the anisotropic conductive adhesive is a photoreactive anisotropic conductive adhesive, the adhesive is not limited to the photo-assist type. As mentioned above, it is possible to adopt an adhesive (photo-curing adhesive) which is cured by irradiation of light such as an ultraviolet ray and a visible ray.
Namely, in the present invention, the photoreactive anisotropic conductive adhesive is an adhesive (photo-curing adhesive) whose curing reaction is developed by irradiating light such as an ultraviolet ray and a visible ray, and an adhesive (photo-assist thermosetting adhesive) in which activation is improved by irradiating light such as an ultraviolet ray and a visible ray, and the curing is developed by performing a heating operation at a relatively low temperature.
In contrast, in Embodiments 1 through 3, when the input/output terminals 14 disposed (formed) on the active-matrix substrate 1 are electrically connected to the electric circuits (external member) such as the TCP substrates 17, the photo-curing anisotropic conductive adhesive is used. However, if the anisotropic conductive adhesive is a photoreactive anisotropic conductive adhesive, the adhesive is not limited to an adhesive (photo-curing adhesive) whose curing reaction is developed by irradiation of light such as an ultraviolet ray and a visible ray. Thus, it is possible to adopt an adhesive (photo-assist thermosetting adhesive) in which activation is improved by irradiating light such as an ultraviolet ray and a visible ray, and the curing is developed by performing a heating operation at a relatively low temperature.
As described above, when the photo-assist anisotropic conductive adhesive is used, activation is improved by, for example, a radical appearing in the adhesive due to irradiation of light such as an ultraviolet ray and a visible ray. Hence, after the irradiation of light or simultaneously with the irradiation of light, a heating operation is performed at a relatively low temperature, for example, around 100° C., or more preferably, a heating operation is performed at a temperature (60° C. to less than 80° C.), where the crystallization of the amorphous semiconductor layer can be reduced or prevented. Thus, the curing can be improved.
In this case, the two-dimensional image detector and the display device include a bonding part for electrically connecting the input/output terminals to the outside, and the bonding part is made of an anisotropic conductive adhesive having photo-reactivity.
Namely, for instance, when the amorphous semiconductor layer has selenium as a main component, a film (a-Se film) made of amorphous selenium is a unique material which has a very low crystallizing temperature of 60° C. to 80° C., normally, at 70° C., and crystallization is developed at this temperature or more. Therefore, with this arrangement, as the amorphous semiconductor layer of the two-dimensional image detector, it is possible to use an amorphous semiconductor layer, in which crystallization is developed by a heating operation even at a relatively low temperature of 60° C. to 80° C., for example, an a-Se film having selenium as a main component.
To be specific, the active-matrix substrate of the present invention is provided with the electrode wires disposed in a lattice form, a plurality of the switching elements disposed respectively at the intersections of the electrode wires, and the input/output terminals for inputting and outputting an electronic signal from the outside to the electrode wires, wherein the electrode wires are formed by metal electrodes, plate-shaped electrodes, which are made of a material selected from ITO, SnO2, and ZnO with the property of transmitting light such as a visible ray and an ultraviolet ray, are used only for the input/output terminals disposed on ends of the electrode wires, and the openings penetrating the input/output terminals in a thickness direction are disposed so as to transmit light to the input/output terminals in a sufficient amount to develop a reaction caused by light (photo-reactivity) in the anisotropic conductive adhesive; thus, it is possible to achieve enough transparency to a visible ray and an ultraviolet ray and to maintain a resistance value of the electrode wires.
Here, the electrode wires and the input/output terminals can have a laminated structure in which a part made of a metal part (metal electrode) and a transparent conductive) oxide film (transparent electrode) are stacked.
JPH0541091U Title not available
JPH04317146A Title not available
JPH04362925A Title not available
JPH07302973A Title not available
JPH10213664A Title not available
1 Japanese Office Action dated May 6, 2003 (along with English Translation thereof).
2 Jeromin et al, "8.4: Application of a-Si Active-Matrix Technology in a X-Ray Detector Panel", SID 97 Digest, 1997, pp. 91-94.
3 Lee et a, "A New Digital Detector for Projection Radiography", SPIE, vol. 2432, Jul. 1995, pp. 237-249.
U.S. Classification 250/214.1, 348/E05.086
International Classification H01L27/146, H01L27/14, H01L31/09, G02F1/1345, H04N5/32, G09F9/00, H05K3/32, H05K3/36, G02F1/13
Cooperative Classification H05K2201/0108, H05K3/323, H01L27/14603, H05K3/361, H04N5/32, H01L27/1469, H01L27/14609, H01L27/14676, H01L27/3276, G02F1/13452
European Classification H01L27/32M2W, H01L27/146P5, H01L27/146A2, H01L27/146V8, H05K3/32B2