JP3411023B2 - Board assembly equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for assembling substrates to be bonded in a vacuum chamber while holding and opposing the substrates to be bonded to each other and narrowing the gap in a vacuum. . 2. Description of the Related Art In the manufacture of a liquid crystal display panel, an adhesive (hereinafter, referred to as a glass substrate) having two glass substrates provided with a transparent electrode and a thin film transistor array at an extremely close interval of about several μm.
There is a step of bonding together (hereinafter, the substrate after bonding is called a cell) by sealing with a liquid crystal in a space formed by the bonding. In order to seal the liquid crystal, the liquid crystal is dropped on one of the substrates in which a sealing agent is drawn in a closed pattern so that no injection port is provided, and the other substrate is disposed on the one of the substrates. A method proposed in Japanese Patent Application Laid-Open No. 62-165622, in which the upper and lower substrates are brought close together in a vacuum,
There is a method proposed in Japanese Patent Application Laid-Open No. Hei 10-26763 in which a pattern is drawn on a sealant so as to provide an injection port on one of the substrates, and the substrates are bonded in a vacuum and then injected from the injection port of the sealant. [0004] In the above-mentioned prior art, both substrates are bonded in a vacuum regardless of before and after the pattern drawing of the sealant. In a vacuum, the substrate cannot be suction-adsorbed due to a pressure difference from the atmosphere as in the atmospheric state. When the edge of a substrate located above (hereinafter referred to as an upper substrate) is mechanically held, the central portion of the substrate bends, and the deflection increases with the recent tendency of the substrate to become larger and thinner. ing. Since the positioning is performed by using the alignment marks provided on the peripheral edges of the upper and lower substrates, the larger the deflection, the wider the distance between the ends of the two substrates and the more the alignment becomes impossible. Further, the lower substrate (hereinafter, referred to as the lower substrate) has a central portion of the upper substrate which is bent before the peripheral portion due to the deflection of the upper substrate.
Therefore, the spacers scattered between the substrates move in order to keep the distance between the substrates constant, thereby damaging the alignment film and the like formed on the substrates. Actually, since the upper and lower substrates to be bonded are the same size, the holding margin is hardly removed. SUMMARY OF THE INVENTION An object of the present invention is to provide a substrate assembling apparatus capable of bonding substrates of the same degree with high precision in a vacuum even if the substrate size is increased and thinned. [0010] In order to achieve the above object, the present invention provides a method for holding one substrate to be bonded to the lower surface of a pressure plate located above in a vacuum chamber, and for holding the other substrate to be bonded. Assembling the substrates by holding the substrates on a table located in the lower part of the vacuum chamber so that the two substrates face each other, and using an adhesive provided on one of the substrates to reduce the distance between the two substrates in a vacuum and bond the substrates together In the apparatus, there is provided a moving mechanism for horizontally moving the table between inside and outside of the vacuum chamber, and means for drawing an adhesive on the other substrate held on the table located outside the vacuum chamber in a closed pattern. And means for dropping liquid crystal in the closed pattern of the adhesive on the other substrate, and means for holding the one substrate by suction attraction to the pressure plate;
A means for holding the substrate by electrostatic attraction force, and receiving one of the substrates falling from the pressure plate at a position slightly away from the pressure plate while the suction attraction does not work in the process of reducing the pressure in the vacuum chamber. Receiving means, and means for moving the receiving means to the pressure plate side, and when one of the substrates is present in the receiving means, an electrostatic attraction force is applied to hold the one substrate on the pressure plate. And means for causing it to be provided. An embodiment of the present invention will be described below with reference to the drawings. 1 to 3, the substrate assembling apparatus of the present invention comprises a liquid crystal dropping portion S1 and a substrate bonding portion S2, and both portions are disposed adjacent to each other on the gantry 2. Above the gantry 2, there is a frame 3 that supports the substrate bonding portion S2. An XYθ stage T1 is provided on the upper surface of the gantry 2. The X stage 4a is driven by the drive motor 5 in the left and right X-axis directions on the drawing, that is, the liquid crystal dropping portion S1.
And the substrate bonding portion S2. Y
The stage 4b is on the X stage 4a, and can be moved by the drive motor 6 in the Y-axis direction orthogonal to the X stage. θ stage 4c is on Y stage 4b,
A table 9 on which a substrate is mounted is fixed on the θ stage 4c so as to be rotatable horizontally with respect to the Y stage 4b by a drive motor 8 via a rotary bearing 7. The lower chamber 10 is fixed to the Y stage 4b by a plate 13. stage 4c is connected to the lower chamber 10 via a rotary bearing 11 and a vacuum seal
Can be freely rotated about the center of rotation, and the θ stage 4
Even if c rotates, the lower chamber 10 is suspended and does not rotate. The liquid crystal dropping unit S1 is provided with a dispenser 17 supported by a bracket 14 protruding from the frame 3 for dropping a desired amount of liquid crystal agent onto the lower substrate 1a held on the table 9, and for moving the dispenser 17 up and down. Z axis stage 1
5 and a motor 16 for driving the same. Lower substrate 1
XYθ stage T1 holding a mounted on table 9
Moves in the X and Y directions with respect to the nozzle 18 of the dispenser 17 for dropping the liquid crystal agent. Thereby, the lower substrate 1
A desired amount of liquid crystal agent is dropped at an arbitrary position on a. X holding and holding the lower substrate 1a after dropping the liquid crystal
The Yθ stage T1 is moved by the drive motor 5 below the substrate bonding portion S2. The substrate bonding portion S2 has a structure in which the upper chamber 21 and the electrostatic attraction plate 28 therein can be independently moved up and down. That is, the upper chamber 21 has a housing 30 containing a linear bush and a vacuum seal, and is moved in the vertical Z-axis direction by a cylinder 22 fixed to the frame 2 using the shaft 29 as a guide. When the XYθ stage T1 is moved to the substrate bonding portion S2 and the upper chamber 21 is lowered, the lower chamber 1
O-ring 44 disposed around the upper chamber 21
Are brought into contact with each other and become integral with each other, and at this time, a state of functioning as a vacuum chamber is established. The amount of collapse of the O-ring 44 depends on the upper chamber 2
The lowering stop position is adjusted so that the inside of the vacuum chamber can be kept at a vacuum and the maximum elasticity can be obtained. The housing 30 has a built-in vacuum seal that can move up and down without causing a vacuum leak to the shaft 29 even if the upper chamber 21 is deformed by forming the vacuum chamber with the lower chamber 10. The deformation of the chamber can absorb the force applied to the shaft 29, and the deformation of the pressure plate 27 fixed to the shaft 29 and holding the electrostatic attraction plate 28 can be substantially prevented, and can be held at the electrostatic attraction plate 28 as described later. The bonded upper substrate 1b and the lower substrate 1a held on the table 9 can be bonded while maintaining the parallelism. Reference numeral 23 denotes a vacuum valve, and reference numeral 24 denotes a piping hose connected to a vacuum source (not shown), and these are used when the vacuum chamber is decompressed and evacuated. Reference numeral 25 denotes a gas purge valve, and reference numeral 26 denotes a gas tube, which is connected to a pressure source such as N2 or clean dry air. These are used when returning the vacuum chamber to atmospheric pressure. The upper substrate 1b is held in close contact with the lower surface of the electrostatic attraction plate 28, but the upper substrate 1b is held by the electrostatic attraction plate 28 by suction at atmospheric pressure. That is,
Reference numeral 41 denotes a suction / suction joint, and reference numeral 42 denotes a suction tube, which is connected to a vacuum source (not shown). The surface of the electrostatic suction plate 28 has a plurality of suction holes connected thereto. When the surrounding area is the atmosphere, electrostatic attraction may be used together, or when the electrostatic attraction force is large, suction attraction may be unnecessary. The electrostatic attraction plate 28 is attached to a pressure plate 27 supported by a shaft 29, and the shaft 29 is fixed to housings 31, 32. The housing 31 is attached to the frame 2 by a linear guide 34, and the electrostatic attraction plate 28 has a structure capable of moving up and down. The vertical drive is performed by a motor 40 fixed to a bracket 38 on a frame 35 connected to the frame 2. The transmission of the drive is executed by the ball screw 36 and the nut housing 37. The nut housing 37 is connected to the housing 32 via a load meter 33, and operates integrally with the electrostatic suction plate 28 below the nut 32. Therefore, the shaft 29 is driven by the motor 40.
Is lowered, the electrostatic attraction plate 28 holding the upper substrate 1b is lowered, and the upper substrate 1b is brought into close contact with the lower substrate 1a on the table 9 to apply a pressing force. In this case, the load meter 33 functions as a pressing force sensor, and by sequentially controlling the motor 40 based on a signal fed back, a desired pressing force can be applied to the upper and lower substrates 1a and 1b. Since the lower substrate 1a is mounted in the direction of gravity, FIG.
As shown in the figure, it is sufficient to fix the positioning by pressing the positioning member 81 provided on the table 9 in the horizontal direction by the pressing roller 82, but at the time of the minute positioning immediately before bonding, the upper substrate 1b is placed on the lower substrate 1a. There is a possibility that the lower substrate 1a may shift or lift due to the contact with the sealing agent or the liquid crystal agent, and the air that has entered between the lower substrate 1a and the table 9 in the process of reducing the pressure in the vacuum chamber and evacuating may be reduced. Since there is a possibility that the lower substrate 1a may escape and fluctuate, the table 9 may be provided with a function of electrostatic attraction. If the table 9 is provided with pins that can move in the vertical Z-axis direction and is grounded, it is possible to easily prevent the cells from being charged after the substrates are bonded and remove the cells from the table 9 easily. In FIG. 2, reference numeral 60 denotes a position slightly below the electrostatic attraction plate 28 when the upper substrate 1b is dropped when the vacuum suction chamber 28 is depressurized and the suction attraction force disappears and the upper substrate 1b falls. The receiving claw is received at the position, and is supported by the shaft 59 extending downward at two diagonal positions of the upper substrate 1b. More specifically, as shown in FIG. 3, the shaft 59 is vacuum-sealed through the housing 58 of the upper chamber 21 so that it can rotate and move up and down. That is, the shaft 59 is provided with a lifting actuator 62 fixed to a bracket 63 provided on the shaft 29.
As a result, not only can the shaft 29 be moved up and down independently of the up and down movement, but also the shaft 29 can be rotated by the rotary actuator 61. Next, the electrostatic attraction plate 28 for attracting a substrate will be described. The electrostatic attraction plate 28 is an insulating plate and has two rectangular concave portions. The flat electrode built in each concave portion is covered with a dielectric, and the main surface of the dielectric is electrostatic. It is flush with the lower surface of the suction plate 28. Each buried plate electrode is connected to a positive / negative DC power supply via an appropriate switch. Therefore, when a positive or negative voltage is applied to each plate electrode, a negative or positive charge is induced on the main surface of the dielectric which is flush with the lower surface of the electrostatic chucking plate 28, and The upper substrate 1b is electrostatically attracted by a Coulomb force generated between the upper substrate 1b and the transparent electrode film due to the electric charge.
The voltage applied to each plate electrode may be the same polarity or different bipolar electrodes. Next, a description will be given of a step of bonding substrates by the present substrate assembling apparatus. First, the jig holding the upper substrate 1b is mounted on the table 9, and the XYθ stage T1 is moved by the drive motor 5 to the substrate bonding section S2. Then, the pressure plate 27 and the electrostatic attraction plate 28 are lowered by the motor 40 via the shaft 29, and the upper substrate 1b on the table 9 is sucked and adsorbed. Then, the upper substrate 1b is raised by the motor 40 to bring the upper substrate 1b into a standby state. I do. The XYθ stage T1 returns to the liquid crystal dropping unit S1 and the empty jig is removed, and the lower substrate 1 is placed on the table 9.
a is mounted and fixedly held at a desired position as shown in FIG. Although not shown in FIG. 1, there is a dispenser for discharging the sealant on the frame 3, and the sealant is discharged while moving the lower substrate 1a in the XY-axis directions by the motors 5 and 6 of the XYθ stage T1. Then, the sealant can be drawn on the lower substrate 1a in a closed (closed) pattern.
Thereafter, a liquid crystal agent is dropped from the dispenser 17 onto the lower substrate 1a. In this case, the sealing agent does not function as a dam, and the dropped liquid crystal agent does not flow away. Next, the XYθ stage T1 is connected to the substrate bonding portion S
2, the upper chamber 21 is lowered by the cylinder 22, and the flange portion 21a is brought into contact with the O-ring 44 to form the lower chamber 10 and the vacuum chamber. And
The vacuum valve 23 is opened to reduce the pressure inside the vacuum chamber. At this time, since the upper substrate 1b is in a state of being suction-adsorbed by the electrostatic attraction plate 28, as the decompression proceeds and the vacuum is applied, the suction-adsorbing force acting on the upper substrate 1b disappears,
The upper substrate 1b falls under its own weight. This is received by the receiving claw 60 as shown in FIG. 2 and is held at a position slightly below the electrostatic attraction plate 28 as shown in FIG. When the inside of the vacuum chamber is sufficiently evacuated, a voltage is applied to the electrostatic attraction plate 28 to hold the upper substrate 1b on the receiving claw 60 on the electrostatic attraction plate 28 by Coulomb force. In this case, since the vacuum has already been established, no air remains between the electrostatic attraction plate 28 and the upper substrate 1b, and the upper substrate 1b does not dance when the air escapes. More importantly, the upper substrate 1b is in close contact with the electrostatic attraction plate 28 without air. Therefore, no discharge is generated by the induced charge. When a discharge is generated while leaving air, the air expands, and the upper substrate 1b may be peeled off from the electrostatic attraction plate 28 or the upper substrate 1b made of thin glass may be destroyed. Since no air is present, such abnormal accidents do not occur. After that, the shaft 59 is lowered by the lifting / lowering actuator 62, and then the shaft 59 is rotated by the rotating actuator 61 so that the receiving claw 60 does not hinder the bonding of the upper and lower substrates. The pressure plate 27 is lowered at 40 and the motor 40 is controlled while measuring the pressing force with the load meter 33 to bond the upper and lower substrates 1a and 1b at a desired interval. In this case, since the upper substrate 1b is in close contact with the electrostatic attraction plate 28 and its central portion does not hang down, it adversely affects the spacers in the liquid crystal agent and makes it impossible to align the substrates. Never be. Incidentally, the alignment is performed by reading the alignment marks provided on the upper and lower substrates 1a and 1b with an image recognition camera from a viewing window provided in the upper chamber 21 (not shown), and measuring the position by image processing, and the XYθ stage T1 Each of the stages 4a to 4c is slightly moved to perform high-accuracy positioning. When the bonding is completed, the vacuum valve 23
To open the gas purge valve 25, supply N2 and clean dry air into the vacuum chamber, return to atmospheric pressure, close the gas purge valve 25, raise the upper chamber 21 with the cylinder 22, and move the XYθ stage T1 to the liquid crystal. Returning to the dropping portion S1, the cell is removed from the table 9 to prepare for the next bonding. Here, since the cell after bonding may be charged, it is preferable to remove the cell from the table 9 after performing a charge removal treatment such as contacting with a grounded charge removal bar or blowing ion wind. The sealing agent is hardened in the cell removed from the table 9 by a UV light irradiation device or a heating device on the downstream side. In the above embodiment, since the sealing agent is discharged, the liquid crystal is dropped, and the process immediately proceeds to the bonding, the production yield can be improved since the substrate is less likely to receive dust. Also, XY
The θ stage T1 can be used to transfer the upper substrate 1b into the vacuum chamber, and the size of the apparatus is reduced. The present invention is not limited to the embodiment described above.
You may implement as follows. (1) To supply the upper substrate 1b to the electrostatic attraction plate 28, a plurality of receiving claws (equivalent to the receiving claws 60 in FIG. 2) which can expand and contract in the vertical direction are provided on the XYθ stage T1. Here, when the XYθ stage T1 is at the liquid crystal dropping portion S1, the upper substrate 1b may be placed on the plurality of receiving claws, and the XYθ stage T1 may be moved to the substrate bonding portion S2. (2) Further, the suction may be directly performed on the electrostatic suction plate 28 from the robot hand. (3) The receiving claw provided on the XYθ stage T1 described in the above (1) may receive the upper substrate 1b which falls as the decompression proceeds. (4) Further, the receiving claw 60 shown in FIG. 2 or the receiving claw provided on the XYθ stage T1 described in the above (1) is used to hold the upper substrate 1b before the upper substrate 1b falls. Alternatively, the pressure may be switched to the electrostatic attraction by advancing the pressure reduction from the state of being attracted and attracted to the electrostatic attraction plate 28 after being pressed against the electrostatic attraction plate 28. In this case, by preventing the upper substrate 1b from being physically in close contact with the electrostatic attraction plate 28,
The air between the upper substrate 1b and the electrostatic attraction plate 28 can be evacuated and reduced in pressure. (5) Further, the upper substrate 1b is slightly separated from the electrostatic attraction plate 28 by the receiving claw 60 of FIG. 2 or the receiving claw provided on the XYθ stage T1 described in the above (1). And the electrostatic attraction may be performed during the decompression without suction and attraction. (6) In FIG. 2, two corners (two corners forming a diagonal) of the upper substrate 1b are held by the receiving claws 60, but four corners of the upper substrate 1b are held. (Four corners) may be held, or four sides, two sides in the longitudinal direction, or two sides in the width direction of the upper substrate 1b may be held by appropriate means. As described above, according to the present invention, even if the size of the substrate is increased and the thickness of the substrate is reduced, it is possible to precisely bond substrates of the same size in a vacuum.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of a substrate assembling apparatus showing one embodiment of the present invention. FIG. 2 is a perspective view showing a situation when upper and lower substrates are bonded together. FIG. 3 is a cross-sectional view of a main part showing a state immediately before the upper and lower substrates are bonded by applying an electrostatic attraction force to an upper substrate. [Explanation of References] S2 Substrate bonding portion 1a Lower substrate 1b Upper substrate 9 Table 10 Lower chamber 21 Upper chamber 23 Vacuum valve 27 Pressurizing plate 28 Electrostatic suction plate 59 Shaft 61 Rotating actuator 62 Elevating actuator

Continued on the front page (72) Inventor Masayuki Saito 5-2-2 Koyodai, Ryugasaki, Ibaraki Pref. Hitachi Techno Engineering Co., Ltd. (72) Inventor Yukihiro Kawasumi 5-2-2 Koyodai, Ryugasaki-shi, Ibaraki Hitachi Techno Engineering Co., Ltd. Development Laboratory (72) Inventor Haruo Sankai 5-2-2 Koyodai, Ryugasaki City, Ibaraki Prefecture Hitachi Techno Engineering Co., Ltd. Development Laboratory (72) Inventor Akira Hirai 5-2-2 Koyodai, Ryugasaki City, Ibaraki Prefecture Development of Hitachi Techno Engineering Co., Ltd. In the laboratory (56) References JP-A-11-281988 (JP, A) JP-A-2000-66163 (JP, A) JP-A-6-123924 (JP, A) JP-A-7-106303 (JP, A) (58) Field surveyed (Int.Cl. ⁷ , DB name) G02F 1/13-1/141 G09F 9/30 C03B 23/00-35/26

Claims (1)

(57) [Claim 1] Holding one substrate to be bonded to the lower surface of a pressure plate located above in a vacuum chamber, and positioning the other substrate to be bonded below in a vacuum chamber. In a board assembling apparatus where both substrates are opposed to each other while holding them on a table, and the gap between the two substrates is reduced in vacuum with an adhesive provided on one of the substrates, the table is placed between the inside and outside of the vacuum chamber. Means for drawing the adhesive in a closed pattern on the other substrate held on a table located outside the vacuum chamber, and a means for horizontally moving the adhesive on the other substrate; Means for dropping liquid crystal in the closed pattern of the above, wherein means for holding one of the substrates by suction attraction force and means for holding one substrate by electrostatic attraction force are provided on the pressure plate; Receiving means for receiving one of the substrates falling from the pressure plate at a position slightly away from the pressure plate while the suction force does not work in the process of increasing the pressure in the chamber, and moving the reception means to the pressure plate side. Means for moving, when the receiving means has one substrate, means for applying an electrostatic attraction force to hold the one substrate on the pressing plate, and Assembly equipment.