US20050147743A1 - Fabrication of functional device mounting board making use of inkjet technique - Google Patents

Fabrication of functional device mounting board making use of inkjet technique Download PDF

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US20050147743A1
US20050147743A1 US11/063,897 US6389705A US2005147743A1 US 20050147743 A1 US20050147743 A1 US 20050147743A1 US 6389705 A US6389705 A US 6389705A US 2005147743 A1 US2005147743 A1 US 2005147743A1
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Prior art keywords
substrate
functional device
mounting board
functional
device mounting
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Abandoned
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US11/063,897
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Takuro Sekiya
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Takuro Sekiya
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Priority to JP2002-068033 priority Critical
Priority to JP2002068033 priority
Priority to JP2002-316419 priority
Priority to JP2002316419A priority patent/JP3838964B2/en
Priority to US10/386,056 priority patent/US6918666B2/en
Application filed by Takuro Sekiya filed Critical Takuro Sekiya
Priority to US11/063,897 priority patent/US20050147743A1/en
Publication of US20050147743A1 publication Critical patent/US20050147743A1/en
Application status is Abandoned legal-status Critical

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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B41PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41JTYPEWRITERS; SELECTIVE PRINTING MECHANISMS, e.g. INK-JET PRINTERS, THERMAL PRINTERS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/005Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
    • B41J2/01Ink jet
    • B41J2/135Nozzles
    • B41J2/14Structure thereof only for on-demand ink jet heads
    • B41J2/14016Structure of bubble jet print heads
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS, OR APPARATUS
    • G02B5/00Optical elements other than lenses
    • G02B5/20Filters
    • G02B5/201Filters in the form of arrays
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H01L51/00Solid state devices using organic materials as the active part, or using a combination of organic materials with other materials as the active part; Processes or apparatus specially adapted for the manufacture or treatment of such devices, or of parts thereof
    • H01L51/50Solid state devices using organic materials as the active part, or using a combination of organic materials with other materials as the active part; Processes or apparatus specially adapted for the manufacture or treatment of such devices, or of parts thereof specially adapted for light emission, e.g. organic light emitting diodes [OLED] or polymer light emitting devices [PLED];
    • H01L51/52Details of devices
    • H01L51/5237Passivation; Containers; Encapsulation, e.g. against humidity
    • H01L51/524Sealing arrangements having a self-supporting structure, e.g. containers
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B41PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41JTYPEWRITERS; SELECTIVE PRINTING MECHANISMS, e.g. INK-JET PRINTERS, THERMAL PRINTERS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2202/00Embodiments of or processes related to ink-jet or thermal heads
    • B41J2202/01Embodiments of or processes related to ink-jet heads
    • B41J2202/09Ink jet technology used for manufacturing optical filters
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B41PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41JTYPEWRITERS; SELECTIVE PRINTING MECHANISMS, e.g. INK-JET PRINTERS, THERMAL PRINTERS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2202/00Embodiments of or processes related to ink-jet or thermal heads
    • B41J2202/01Embodiments of or processes related to ink-jet heads
    • B41J2202/20Modules
    • HELECTRICITY
    • H05ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05KPRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K3/00Apparatus or processes for manufacturing printed circuits
    • H05K3/10Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern
    • H05K3/12Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern using thick film techniques, e.g. printing techniques to apply the conductive material or similar techniques for applying conductive paste or ink patterns
    • H05K3/1241Apparatus or processes for manufacturing printed circuits in which conductive material is applied to the insulating support in such a manner as to form the desired conductive pattern using thick film techniques, e.g. printing techniques to apply the conductive material or similar techniques for applying conductive paste or ink patterns by ink-jet printing or drawing by dispensing

Abstract

An apparatus for fabricating a functional device mounting board comprises a holder for holding a substrate on which functional devices are to be formed, a jet head for ejecting a droplet containing a functional material onto the substrate, and a data input unit for supplying droplet ejection information to the jet head. The jet head ejects the droplets onto the substrate based on the droplet ejection information so as to form the functional device in the functional device forming area. The functional device is formed by allowing a volatile ingredient of the droplet, while allowing a solid component of the droplet to remain on the substrate.

Description

    BACKGROUND OF THE INVENTION
  • 1. Field of the Invention
  • The present invention generally relates to fabrication of a functional device mounting board, using an ejector to form a functional device on a substrate. More particularly, the present invention relates to an apparatus and a system for fabricating the functional device mounting board, as well as a functional device mounting board itself fabricated using the apparatus or the system.
  • 2. Description of the Related Art
  • In recent years, luminescent devices (or light-emitting devices) using organic materials have been developed for use in a spontaneous luminescent display, which has been spreading in place of a liquid crystal display. In general, the luminescent device is formed using a photolithography technique to pattern a layer of a functional material into a predetermined shape. For example, it is known that an organic electroluminescent (hereinafter, referred to as “organic EL”) device is fabricated by forming a layer of a low molecular-weight material by vapor deposition (or vacuum evaporation)., and then patterning the layer by photolithography. See “Organic Electroluminescent Diodes”, C. W. Tang and S. A. VanSlyke, Appl. Phys. Lett. 51, 913 (1987). To fabricate a color organic EL device, different luminescent materials are formed on prescribed pixels by vapor deposition. However, since vacuum evaporation and photolithography are high-cost processes requiring a number of steps, it is disadvantageous to employ these techniques to fabricate luminescent devices over a wide area.
  • To overcome this problem, the applicant has come across an idea that inkjet droplet ejection means can be used to place a functional material at a desired position, without employing high-cost processes, such as vacuum evaporation and photolithography. Inkjet droplet ejection means are disclosed in U.S. Pat. Nos. 3,060,429, 3,298,030, 3,596,275, 3,416,153, 3,747,120, and 5,729,257. It is expected that a technique of inkjet droplet ejection can be replaced for photolithography, and that the inkjet technique can realize more stable formation of a functional device at low cost and a high yield rate.
  • For example, when fabricating an organic EL device as an example of the functional device, a pattern of a hole-transporting layer and a light-emissive layer can be formed on a transparent electrode substrate by ejecting a solution, in which a hole-transporting material and a luminescent material are dissolve or dispersed in a solvent, from the inkjet head.
  • The same idea is disclosed in JPA2000-323276 and JAP2001-60493. However, these publications only discuss the materials for organic EL devices suitable to the inkjet method, and do not sufficiently refer to either an apparatus for forming such a functional device on a substrate using an inkjet technique, or a functional device mounting board fabricated using the inkjet technique.
  • Applying the inkjet technique to fabrication of functional devices is not easy because the conventional inkjet technique is limited to ejecting ink onto paper. There are still many unsolved factors concerning how to eject a solution containing a functional material onto a substrate in a stable manner. Especially, a great deal of work is required to realize a group of functional devices formed on a substrate at highly precise patterns efficiently.
  • SUMMARY OF THE INVENTION
  • Therefore, it is an object of the present invention to provide a novel apparatus for fabricating a group of functional devices on a substrate at low cost using a simple technique. This apparatus is capable of fabricating the functional devices at high precision, and accordingly, it can produce a high-quality functional device mounting board.
  • It is another object of the invention to guarantee safe operation even if a solution containing the functional material leaks out due to an unexpected accident.
  • It is still another object of the invention to prevent undesirable clog in the jet head in order to guarantee reliable ejecting operation.
  • It is yet another object of the invention to provide a system for fabricating a functional device mounting board.
  • It is yet another object of the invention to provide a functional device mounting board with a precise pattern of functional device array.
  • It is yet another object of the invention to provide an image display apparatus using the functional device mounting board.
  • To achieve the objects, in one aspect of the invention, an apparatus for fabricating a functional device mounting board is provided. The apparatus comprises (a) a holder for holding a substrate on which a functional device is to be formed, (b) a jet head for ejecting a droplet containing a functional material onto the substrate so as to form the functional device in a functional device forming area of the substrate by allowing the volatile ingredient of the droplet to vaporize, while allowing the solid component to remain on the substrate, and (c) a data input unit for supplying droplet ejection information to the jet head. The jet head ejects the droplet onto the substrate based on the droplet ejection information so as to form the functional device in the functional device forming area.
  • With this apparatus, functional device mounting boards can be fabricated at high precision using a simple structure.
  • The apparatus further has a driving unit that moves at least one of the jet head and the holder relatively to the other so as to define a droplet ejecting area of the jet head broader than the functional device forming area of the substrate. tion.
  • Preferably, the jet head ejects the droplet using a mechanical displacement force so that the droplet becomes spherical immediately before the droplet reaches the substrate.
  • Alternatively, the jet head ejects the droplet using a mechanical displacement force so that the droplet has an elongated shape along the ejecting direction without a trailing droplet, and so that the length of the elongated droplet does not exceed three times the diameter of the droplet.
  • These arrangements allow the apparatus to form a prescribed pattern of the functional device at a desired position on the substrate precisely.
  • The apparatus further comprises a reservoir positioned under the substrate for containing a solution of the functional material, and a flexible tube connecting the reservoir to the jet head.
  • This arrangement is advantageous as a safeguard preparing for unexpected leakage of the solution.
  • The apparatus further comprises maintenance equipment positioned outside the holder. The maintenance equipment caps the droplet ejecting face of the jet head, and evacuates the solution containing the functional material from the jet head.
  • This arrangement effectively prevents the solution containing the functional material from blocking in the jet head.
  • The jet head may be comprised of a set of multi-nozzle jet heads arranged apart from each other. In this case, each of the multi-nozzle jet heads has a row of nozzles, and is capable of ejecting a droplet of a different type of solution of the functional material. The jet head is mounted on a carriage driven by the driving unit, so that the row of nozzles of each of the multi-nozzle jet heads is not parallel to a carriage moving direction.
  • For example, each of the multi-nozzle jet heads ejects a different type of solution containing an organic electroluminescent material that emits light of a different color.
  • Preferably, droplet ejection speed is faster than the relative moving speed between the jet head and the substrate.
  • In another aspect of the invention, a system for fabricating functional device mounting boards is provided. The system comprises (a) a fabrication apparatus that fabricates a functional device mounting board by ejecting a droplet of a solution containing a functional material from a jet head toward a substrate held on a holder, while moving the jet head relatively to the substrate, based on droplet ejection information supplied to the jet head; and (b) a clean air supply unit that supplies clean air to the droplet ejection area on the substrate.
  • In still another aspect of the invention, a functional device mounting board, which is fabricated by the above-described apparatus or system, is provided. The functional device mounting board comprises (a) a substrate having a top face and a rear face, (b) a group of functional devices arranged in a matrix in a functional device forming area defined on the top face of the substrate, and (c) an information pattern formed outside the functional device forming area on the top face of the substrate. Each of the functional devices is formed as a dot image formed by one or more droplets of a solution containing a functional material.
  • The information pattern is also formed as a dot image, and includes, for example, an identification pattern of the functional device mounting board, or a performance check pattern.
  • Each of the functional devices is formed of a different type of the solution containing an organic electroluminescent material that emits light of a different color.
  • In yet another aspect of the invention, a functional device mounting board comprises (a) a substrate having a top face and a rear face, and (b) a group of functional device arranged in a matrix in a functional device forming area defined on the top face. The roughness of the top face is at or below 0.5 s. Each of the functional devices is formed as a dot image formed by one or more droplets of a solution containing a functional material.
  • Preferably, the roughness of the rear face of the substrate is greater than that of the top face.
  • A groove or a ridge may be formed on the rear face of the substrate.
  • These arrangements prevent the substrate from being stuck on the substrate holder of a fabrication apparatus.
  • At least one of the corners of the substrate are chamfered or rounded. Alternatively, the edges of the substrates are chamfered. This arrangement allows easy and safe handling of the substrate.
  • In yet another aspect of the invention, an image display apparatus using the functional device mounting board is provided. The image display apparatus comprises (a) a functional device mounting board having a group of functional devices arranged in a functional device forming area on a first face of a substrate, and (b) a cover plate facing the functional device mounting board. Each of the functional devices and the information pattern are formed as a dot image formed by one or more droplets of a solution containing a functional material.
  • Preferably, the thickness of the cover plate is greater than that of the functional device mounting board.
  • The cover plate is made of, for example, reinforced glass.
  • In yet another aspect of the invention, an image display apparatus comprises (a) a functional device mounting board having a group of functional devices arranged in a functional device forming area on the first face of the substrate, and (b) a holder having a curved groove. Each of the functional devices is formed as a dot imaged formed by one o more droplets of a solution containing a functional material. The holder holds the functional device mounting board in the curved groove so that the first face of the functional device mounting board is bent with respect to a viewer.
  • BRIEF DESCRIPTION OF THE DRAWINGS
  • Other objects, features, and advantages of the present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings, in which:
  • FIG. 1 schematically illustrates, in a perspective view, ejection of the solution containing a functional material onto an ITO transparent electrode on the glass substrate;
  • FIG. 2 illustrates the overall structure of a fabrication apparatus for a functional device mounting board according to an embodiment of the invention;
  • FIG. 3, illustrates a droplet ejecting apparatus used to form a functional device on a substrate according to an embodiment of the invention;
  • FIG. 4A and FIG. 4B illustrate the jet head unit used in the droplet ejecting apparatus shown in FIG. 3;
  • FIGS. 5A and 5B illustrate an example of the substrate on which functional devices are formed, the substrate having a U-shaped groove on the rear face of the substrate;
  • FIG. 6A and FIG. 6B illustrate another example of the substrate having a V-shaped groove on the rear face of the substrate;
  • FIG. 7A and FIG. 7B illustrate still another example of the substrate having a ridge on the rear face of the substrate;
  • FIG. 8A illustrates an examples of the rectangular substrate having chamfered corners, and FIG. 8B illustrates another example of the rectangular substrate having rounded corners;
  • FIG. 9 illustrates still another example of the rectangular substrate having a chamfered corner and three rounded corners;
  • FIG. 10 illustrates yet another example of the rectangular substrate having chamfered corners and an indentation on a side of the rectangle;
  • FIG. 11A and FIG. 11B illustrate yet another example of the rectangular substrate with chamfered edge lines;
  • FIG. 12 illustrates the corner of the substrate having the chamfered edge lines;
  • FIG. 13A and FIG. 13B illustrates yet other examples of the substrates having a chamfered corner formed on the chamfered edge lines;
  • FIG. 14 illustrates the positional relation between the jet head of the droplet ejecting apparatus and the substrate on which functional devices are to be formed;
  • FIG. 15 is a plan view of the substrate placed on the substrate holder;
  • FIG. 16 illustrates a shape of the droplet ejected from the jet head of the droplet ejecting apparatus according to the invention;
  • FIG. 17 illustrates another shape of the droplet ejected from the jet head of the droplet ejecting apparatus according to the invention;
  • FIG. 18 illustrates still another shape of the droplet ejected from the jet head of the droplet ejecting apparatus by making use of the bubbles;
  • FIG. 19 illustrates an example of the functional device having a functional material formed by one droplet between the electrodes;
  • FIG. 20 illustrates another example of the functional device having a functional material formed by several droplets between the electrodes;
  • FIG. 21 illustrates still another example of the functional device having a functional material formed in two lines between the electrodes, each line consisting of several droplets;
  • FIG. 22A through FIG. 22C illustrate examples of thermal-type jet head suitably applied to the droplet ejecting apparatus of the present invention;
  • FIG. 23 is a front view of a multi-nozzle type jet head;
  • FIG. 24 is a front view of a jet head unit in which several multi-nozzle jet heads are stacked, each multi-nozzle jet head being used for a different type of solution;
  • FIG. 25 is a perspective view of the jet head unit shown in FIG. 23;
  • FIG. 26 illustrates still another example of the multi-nozzle jet head unit having a common nozzle plate;
  • FIG. 27 illustrates yet another example of the multi-nozzle jet head unit having several multi-nozzle jet heads arranged apart from each other;
  • FIG. 28 illustrates the relation between the carriage moving direction and the nozzle arrangement of the jet head when the multi-nozzle jet head unit moves along with the motion of the carriage, while ejecting a solution containing a functional material;
  • FIG. 29 illustrates another example of the nozzle arrangement, in which the direction of multi-nozzle arrangement is parallel to the carriage moving direction;
  • FIG. 30 illustrates still another example of the nozzle arrangement, in which the direction of multi-nozzle arrangement in the stacked jet head unit is parallel to the carriage moving direction;
  • FIG. 31A is a plan view of the functional device mounting board having a group of functional devices in the functional device forming area, while some figures are formed outside the functional device forming area. An example of the functional device is shown in FIG. 31B formed by the jet head shown in FIG. 31C;
  • FIG. 32 is a plan view of another example of the functional device mounting board having a group of functional devices in the functional device forming area, while a performance check pattern is formed outside the functional device forming area;
  • FIG. 33 is a plan view of still another example of the functional device mounting board having a group of functional devices in the functional device forming area, while a second group of functional devices is formed outside the functional device forming area;
  • FIG. 34 is a side view of the fabrication apparatus for a functional device mounting board, having a reliable solution supply system according to an embodiment of the invention, showing the positional relation of the major units;
  • FIG. 35 illustrates an example of solution supply cartridge according to an embodiment of the invention;
  • FIG. 36 illustrates how the solution supply cartridge is used in the fabrication apparatus;
  • FIG. 37 illustrates the solution supply cartridge fit into the fabrication apparatus;
  • FIG. 38 is a side view of another type of fabrication apparatus having a solution supply system, showing another arrangement of the major units;
  • FIG. 39 illustrates an example of the ejection system according to an embodiment of the invention;
  • FIG. 40 illustrates another example of the ejection system;
  • FIG. 41A and FIG. 41B illustrate how the droplet is ejected from the nozzle;
  • FIG. 42 is a cross-sectional view of the jet head having a filter according to an embodiment of the invention;
  • FIG. 43 illustrates a fabrication apparatus for a functional device mounting board, having ejector maintenance equipment according to an embodiment of the invention;
  • FIG. 44A and FIG. 44B illustrate an example of the ejector maintenance equipment;
  • FIG. 45 illustrates an example of the nozzle suction unit provided to the ejector maintenance equipment;
  • FIG. 46A and FIG. 46B illustrate the nozzle of the jet head, which is fit into the suction hole of the ejector maintenance equipment;
  • FIG. 47 illustrates how the solution is evacuated from the nozzle by the nozzle suction unit shown in FIG. 45;
  • FIG. 48A and FIG. 48B illustrate another example of the fabrication apparatus having ejector maintenance equipment that functions inside the droplet ejection area;
  • FIG. 49 illustrates an example of the system for fabricating a functional device mounting board, the system including the fabrication apparatus;
  • FIG. 50 illustrates an example of the jet head having a clean air supply unit
  • FIG. 51 illustrates an example of the organic EL display board fabricated by the fabrication apparatus according to the invention, which is used in a flat state;
  • FIG. 52 illustrates an example of the organic EL display board, which is bent in a convex state toward the viewer;
  • FIG. 53 illustrates an example of the organic EL display board, which is bent in a concave state with respect to the viewer;
  • FIG. 54A and FIG. 54B illustrate how the organic EL display board is held by a guide having a curved guide groove; and
  • FIG. 55A and FIG. 55B illustrate examples of the combination of the organic EL display board and the cover plate.
  • DETAILED DESCRIPTION OF THE EMBODIMENTS
  • The details of the present invention will now be described with reference to the attached drawings.
  • FIG. 1 illustrates fabrication of organic EL devices as an example of the functional devices. In this example, solution 2, in which organic EL material that emits light of red, green, or blue is dissolved, is ejected from a nozzle 1 onto an ITO (indium tin oxide) transparent electrode patterns 4 formed on glass substrate 5. The glass substrate 5 has a barrier wall 3 that defines an array of the transparent electrode pattern 4, and the organic EL devices of the corresponding colors of red, green, and blue are arranged as a mosaic pattern. The composition of the solution 2 is as given below:
    • Solvent: dodecylbenzene/dichlorobenzene (1/1, volume ratio)
    • Red: polyfluorene/perylene dye (98/2, weight ratio)
    • Green: polyfluorene/coumarin dye (98.5/1.5, weight ratio)
    • Blue: polyfluorene
  • The ratio of the solid material to solvent is given as 0.4% (weight/volume). The substrate on which such solution has been applied is heated at, for example, 100° C. to remove the solvent. Then, an appropriate metallic mask is formed on the substrate, and an aluminum layer is formed by vapor deposition up to the thickness of 200 nm (not shown in the drawings). Lead wires are extended out from ITO and aluminum, whereby a device having an ITO anode electrode and an aluminum cathode is completed. Under the application of voltage of approximately 15 volts, the device emits light of red, green or blue.
  • The electrodes may be formed on the substrate in advance, prior to ejecting droplets of the solution. The functional device is formed by letting the volatile ingredient of the solution vaporize such that solid ingredients remain on the substrate.
  • By placing a transparent cover plate made of glass or plastic over the substrate opposing the functional devices, and then enclosing (packaging) it, an image display device, such as a spontaneous luminous organic EL display, can be provided.
  • The functional device is not limited to an organic EL device. For example, an organic transistor or the like may also be suitably fabricated as the functional device by applying the techniques of the present invention. Resist can also be used as the solution containing a functional material applied onto the substrate in forming the barrier wall 3 of the above-described example.
  • In the present invention, inkjet techniques are applied as means for applying the solution containing a functional material. Specific examples of application of the inkjet techniques will be described below.
  • FIG. 2 is a diagram for describing an embodiment of the fabrication apparatus for the functional device mounting board of the present invention. In this diagram, reference numeral 11 denotes a jet head unit (jet head); 12 denotes a carriage; 13 denotes a substrate support bench (or a substrate holder); 14 denotes a substrate on which a functional device is to be formed; 15 denotes a supply tube for the solution that includes functional material; 16 denotes a signal supply cable; 17 denotes a jet head control box; 18 denotes an X-direction scanning motor for the carriage 12; 19 denotes a Y-direction scanning motor for the carriage 12; 20 denotes a computer; 21 denotes a control box; and 22 (22X1, 22Y1, 22X2, 22Y2) denotes substrate positioning/holding means.
  • FIG. 3 is a schematic diagram illustrating the configuration of a droplet applicator used to fabricate the functional device mounting board of the present invention; and FIG. 4 is a schematic diagram of the principle parts of the droplet applicator jet head unit in FIG. 3. The configuration in FIG. 3 differs from that in FIG. 2, where a functional device group is formed on the substrate by making the substrate 14 side move. In FIG. 3 and FIG. 4, a jet head unit 31 is a head alignment control mechanism, 32 is a detection optical system, 33 is an inkjet head, 34 is a fine head alignment mechanism, 35 is a control computer, 36 is an image identification mechanism, 37 is an XY direction scan mechanism, 38 is a position detection mechanism, 39 is a positional correction control mechanism, 40 is an inkjet head drive/control mechanism, 41 is an optical axis, 42 are device electrodes, 43 is a droplet, and 44 is a location for droplet impact. Any appropriate mechanism may be used as the droplet applicator (inkjet head 33) in the jet head unit 11 as long as it can eject fixed quantities of arbitrary droplets, however, a mechanism based on inkjet techniques that is capable of forming droplets ranging from several to several hundreds pl is especially preferable.
  • There are many inkjet methods. For example, an electrical signal is applied to a piezoelectric vibrator so as to convert the electrical signal into mechanical vibration of a piezoelectric vibrator, which causes a droplet to be ejected from a minute nozzle. This method is disclosed in U.S. Pat. No. 3,683,212 (Zoltan method), U.S. Pat. No. 3,747,120 (Stemme method), and U.S. Pat. No. 3,946,398 (Kyser method). This is generally known as a drop-on-demand method.
  • Another method (the Sweet method) is disclosed in, for example, U.S. Pat. Nos. 3,596,275 and 3,298,030. In this method, a droplet of a recording fluid containing a controlled amount of electrostatic charge is produced using a continuous vibration generating technique. The produced droplet of the recording fluid flies between polarizing electrodes under the application of a uniform electric field, so as to reproduce images on a recording member. This is generally called the continuous flow method, or charge control method.
  • Yet another method is disclosed in Japanese Patent Publication after Examination (Koukoku) No. 56-9429. In this method, air bubbles are generated in the fluid, and the bubbles act on the fluid so as to cause a droplet to be ejected from a minute nozzle. This technique is generally called the thermal inkjet method or bubble inkjet method.
  • Among these methods, including the drop-on-demand, the continuous flow method, and the thermal inkjet method, any appropriate method can be chosen in accordance with needs. According to the present invention, an apparatus for fabricating a functional device mounting board (FIG. 2) is used. The holding position of the substrate 14 is fixed by the substrate positioning/holding means 22 for adjusting and determining the substrate holding position. As shown simplified in FIG. 2, the substrate positioning/holding means 22 makes contact with each side of the substrate 14, and is capable of making fine adjustments on the order of microns in the X-direction and the Y-direction. The substrate positioning/holding means 22 is connected to a jet head control box 17, computer 20, and control box 21, thereby allowing for constant feedback of the substrate positioning information, as well as fine adjustment displacement information, droplet positioning information, and ejection timing.
  • Moreover, in addition to the X/Y direction position adjustment mechanism, the fabrication apparatus for the functional device mounting board has a rotational position adjustment mechanism although it is not shown in the drawings (because it is positioned beneath the substrate 14). In connection with this, the shape of the functional device mounting board and array of the functional device group will be described first.
  • Any of silica glass, glass with a reduced impurity content of Na or the like, blue plate glass, a glass substrate with a SiO2 layer, or a ceramics substrate of alumina may be used as the substrate of the functional device mounting board of the present invention. Furthermore, various types of plastic substrates including PET may also be suitably used for the purpose of reducing the weight and increasing flexibility. In any case, the substrate is rectangular, unlike silicon wafers, in view of economical production and supply, and of practical use of the final product (that is, functional device mounting board). Accordingly, the substrate has two vertical sides parallel to each other and two horizontal sides parallel to each other, which configure a rectangular shape. A vertical side and a horizontal side make a right angle.
  • A group of functional devices are arranged in a matrix on the rectangular substrate so that the two mutually orthogonal directions of this matrix are parallel to the directions of the vertical sides and the horizontal sides of this substrate, respectively (see FIG. 31 through FIG. 33). The reasons for this arrangement (i.e., arraying the functional devices in a matrix and making the vertical and horizontal sides of the substrate parallel with the two orthogonal directions of that matrix) will be explained below.
  • As illustrated in FIG. 2 or FIG. 3, once the position of the solution ejecting surface of the jet head unit 11 with respect to the substrate 14 is determined, no particular positional control is required. The jet head unit 11 ejects the solution (for example, photoresist material, a solution of dissolved organic EL material, or conductive material), while moving in the X and Y directions relative to the substrate so as to keep parallel to the functional device forming surface with a fixed distance from the substrate 14. Basically, the X-direction and Y-direction are two mutually orthogonal directions. By setting the vertical side or the horizontal side of the substrate parallel to the Y-direction or X-direction during the positioning, a group of functional devices can be formed precisely using a mechanism of ejecting the solution and a mechanism of causing relative displacement, because the two directions of the matrix array of the functional device are also parallel to the sides of the substrate. In other words, using a rectangular substrate and the relative displacement mechanism in the X and Y directions, and setting the array of the functional devices so that the sides of the array are parallel to the sides of the substrate, allow a matrix of functional devices to be formed at high precision by accurately positioning the substrate prior to ejecting droplets onto the substrate.
  • The rotational position adjustment mechanism mentioned earlier is now described. As previously mentioned, the present invention aims to provide a highly-precise functional device matrix array by accurately positioning the substrate before the ejection of droplets onto the substrate, and by causing relative displacement in the X and Y directions without executing additional control operations. When carrying out initial positioning of the substrate, there may be an offset (or positional shift) existing in the rotational direction about the Z-axis perpendicular to the plane defined by the X and Y directions. In order to compensate for this rotational offset, a rotational position adjustment mechanism (not shown in the drawings since it is positioned beneath the substrate 14) is provided to the fabrication apparatus. By compensating the rotational deviation and by correctly positioning the substrate, a highly precise matrix array of functional devices can be obtained simply by the relative displacement in the X and Y directions.
  • In the above-described example, the rotational position adjustment mechanism has been described as a separate mechanism from the substrate positioning/holding means 22 (22X1, 22Y1, 22X2, 22Y2) of FIG. 2 (not visible since positioned beneath the substrate 14). However, the substrate positioning/holding means 22 may include the rotational position adjustment mechanism. For example, the substrate positioning/holding means 22 makes contact with the sides of the substrate 14, and the whole substrate positioning/holding means 22 is made capable of adjusting the position in the X-direction and Y-direction. In this case, angle adjustment can be conducted by providing two screws positioned apart from each other and movable independently of each other to each of the substrate positioning/holding means 22 that receive one of the sides of the substrate 14. The rotational position control information is supplied to the jet head control box 17, computer 20, and control box 21, together with the X, Y direction positioning information and fine adjustment displacement information. This arrangement allows for constant feedback of droplet positioning information and ejection timing information to the substrate positioning mechanism.
  • Next, another configuration of the positioning means will be described. The substrate positioning/holding means 22 of the above description makes contact with the sides of the substrate 14, and the entirety of the substrate positioning/holding means 22 is capable of adjusting the position of the substrate in the X-direction and Y-direction. Instead of making use of the sides of the substrate, strip-shaped patterns extending in two perpendicular directions may be formed on the substrate 14. As previously mentioned, the functional device array is formed as a matrix. Accordingly, the strip-shaped patterns extending in two perpendicular directions are set parallel to the two mutually orthogonal sides of the matrix. Such patterns can be easily formed on the substrate using a photofabrication technique.
  • Instead of forming the strip-shaped patterns separately only for the purpose of positioning, device electrodes 42 (FIG. 4) or the wiring patterns extending in the X-direction and Y direction may be used as the positioning strip patterns. Such strip-shaped patterns can be detected by a detection optical system 32 using a CCD camera and lens, which will be described with reference to FIG. 4 below, and the detected information can be fed back to the positional adjustment.
  • Concerning the Z direction perpendicular to the X-Y plane, the positional control is not particularly necessary in the Z direction once the positional relationship between the solution ejecting face of the jet head unit 11 and the substrate 14 is initially determined. Namely, the jet head unit 11 ejects the solution containing a functional material, while it moves relative to the substrate 14 in the X and Y directions maintaining a fixed distance from the substrate 14. Positional control of the jet head unit 11 in the Z direction is not performed during the ejection to prevent the associated mechanisms and the control system from becoming complex. In addition, if positional adjustment is carried out in the Z direction during the ejection, it takes a longer time to form the functional device on the substrate through application of droplets, resulting in reduced productivity.
  • Instead of performing positional control in the Z direction during the ejection, the levelness of the substrate 14 and the substrate support means is improved, as well as improving the precision of a carriage mechanism that drives the jet head unit 11 relative to the substrate 14 in the X, Y directions. The productivity is enhanced by increasing the rate of the relative displacement between the jet head unit 11 and substrate 14 in the X, Y directions, even without performing positional control in the Z direction during ejection. To give an example, fluctuation in distance between the substrate 14 and the solution ejecting surface of the jet head unit 11 during the ejection of the droplets is kept within 5 mm (in the case where the size of the substrate 14 is at least 200 mm×200 mm and smaller than 4000 mm×4000 mm).
  • A plane defined by the X and Y directions is generally held horizontal. However, if the substrate 14 is small (for example, when smaller than 500 mm×500 mm), the X-Y plane is not necessarily held horizontal, but should be set so that the positional relationship makes the substrate 14 be located most efficiently for that device.
  • FIG. 3 illustrates another example of the present invention. The present invention is not limited to this example. Unlike in FIG. 2, the substrate 14 is driven relative to the fixed jet head unit 31 when fabricating a functional device mounting board. FIG. 4 is an enlarged diagram of the jet head unit 11 shown in FIG. 3. To begin with, in FIG. 3, reference numeral 37 denotes the XY direction scan mechanism upon which the functional device mounting board 14 is placed and held. The functional device formed on the substrate 14 has the same configuration as that shown in FIG. 1. Each functional device is configured by the glass substrate 5 (equivalent to the substrate 14), the barrier wall 3, and the ITO transparent electrodes 4, as in FIG. 1. The jet head unit 11 for ejecting droplets is positioned above the substrate (or functional device mounting board) 14. In this example, the jet head unit 11 is fixed. By moving the functional device mounting board 14 to an arbitrary position by the XY direction scan mechanism, relative displacement between the jet head unit 11 and functional device mounting board 14 is implemented.
  • FIG. 4 illustrates the configuration of the jet head unit 11. In FIG. 4, reference numeral 32 denotes the detection optical system that takes in the image information of the top face of the substrate 14. The detection optical system 32 is adjacent to the inkjet head 33 that ejects the droplet 43, and is arranged so that the optical axis 41 and focal point of the detection optical system 32 coincides with the location of impact 44 of the droplet 43 through the inkjet head 33. In this case, the positional relationship between the detection optical system 32 and inkjet head 33 illustrated in FIG. 3 can be precisely adjusted via the fine head alignment mechanism 34 and head alignment control mechanism 31. Furthermore, a CCD camera and lens are used for the detection optical system 32.
  • In FIG. 3, the reference numeral 36 denotes the image identification mechanism, which identifies the image information detected by the detection optical system 32. The image identification mechanism 36 converts image contrast into binary data, and calculates the center of balance of a specific portion of the binary contrast. Specifically, the high-resolution image recognition device VX-4210 manufactured by Keyence Corporation may be used. A position detection mechanism 14 provides the position information existing on the substrate 14 to the image information obtained by the image identification mechanism. Length measuring equipment, such as a linear encoder, furnished in the XY direction scan mechanism 37 may be utilized here. The positional correction control mechanism 39 performs positional correction based upon the positional information on the functional device mounting board 14 and image information, whereby movement of the XY direction scan mechanism 37 is corrected. The inkjet head 33 is driven by the inkjet head control/drive mechanism 40, whereby the droplet is applied onto the functional device mounting board 14. Each of the control mechanisms mentioned thus far are centrally controlled by the control computer 35.
  • In this example, the jet head unit 11 is fixed, while relative displacement between the jet head unit 11 and functional device mounting board 14 is implemented through the motion of the functional device mounting board 14 to an arbitrary position by means of the XY direction scan mechanism. Needless to say, however, as illustrated in FIG. 2, the functional device mounting board 14 may be fixed, while driving the jet head unit 11 in the X and Y directions. Particularly in cases of applying in manufacture of midsize substrates 200 mm×200 mm to large size substrates of 2000 mm×2000 mm or larger, the latter structure is preferable, where the functional device mounting board 14 is fixed, while driving the jet head unit 11 scans in the two orthogonal X and Y directions. In this case, droplets of the solution are also ejected along the X direction and Y direction.
  • In contrast, if a light plastic substrate is utilized, or if the size of the substrate is relatively small (100 mm×100 mm through 800 mm×800 mm), paper feeding for a inkjet printer may be used. In this case, the jet head unit 11 mounted on the carriage 12 s