Patent Application
20100003110
The present invention relates to a suction holding apparatus and a suction holding method for suction-holding a substrate, in order to bond, for instance, flat plate-like substrates such as glass substrates.
Liquid crystal panels, organic EL panels and the like are manufactured by, for instance, bonding together glass substrates. Glass substrates, therefore, must be held in the bonding device. Ordinary methods for holding a substrate include, for instance, vacuum suction, as well as holding by way of mechanical chucks, electrostatic chucks and the like.
With a view to, for instance, eliminating air bubbles, vacuum bonding is used in the manufacturing process of liquid crystal panels and the like. The holding apparatus need to hold a substrate from above it in the vacuum area. To this end, Mechanical or electrostatic chucks are often used as well, since the holding force of vacuum suction cannot be maintained.
Patent document 1: Japanese Patent Application Laid-open No. 2003-330031
Patent document 2: Japanese Patent Application Laid-open No. 2002-154647
However, holding of a substrate by way of a mechanical chuck requires a gripping part. As a result, bonding to another substrate of identical size is hampered by the gripped portion, so that the substrate held by the chuck cannot be brought into close contact, in that state, against the other substrate. Meanwhile, the suction force of electrostatic chucks varies greatly depending, for instance, on whether or not a conductive film is formed on the substrate. A further concern is that application of high voltages, of several kV or higher, may damage circuits on the substrate.
To address the above shortcomings, Patent document 1 discloses a technique that involves supplying water onto a substrate, lowering a holding plate to bring the latter into contact with the substrate, and suctioning the substrate against the holding plate, by way of the surface tension of the water interposed between the holding plate and the substrate. Patent document 2 discloses a technique of supplying silicone oil via a plurality of small holes formed on a suction plate that is brought into contact with a substrate, so that the substrate is suctioned on account of the surface tension of the silicone oil interposed between the suction plate and the substrate.
In the above techniques, however, a liquid must be actively supplied onto the substrate. The liquid, therefore, must be prepared beforehand, and there must be provided a device for supplying the liquid, all of which result in a complex and costly apparatus structure that is awkward to control. Moreover, such techniques are inappropriate for products in which large amounts of residual liquid are to be avoided.
An object of the present invention, which is proposed with a view to solving the above problems of conventional art, is to provide a suction holding apparatus and a suction holding method that allow suction-holding a substrate reliably irrespective of substrate type, with a simple and inexpensive structure.
To achieve the above goal, the present invention is a suction holding apparatus for suction-holding a substrate, comprising: suction means having a suction surface; driving means for changing the relative position of the substrate and the suction means; temperature changing means for changing the temperature of the suction surface; and control means for controlling the temperature changing means so as to cause dew condensation on the suction surface when the substrate is suctioned onto the suction surface.
An embodiment of the method of the present invention is a suction holding method for suction-holding a substrate, comprising the steps of causing dew condensation on a suction surface of suction means, by changing the temperature of the suction surface; and pressure-bonding the substrate against the suction surface.
In such an invention, moisture in the atmosphere is condensed on the suction surface of the suction means by changing the temperature of the suction surface. When the substrate is affixed to the suction surface, water spreads very thinly therebetween, and the substrate becomes suctioned strongly onto the suction surface on account of surface tension. The substrate can thus be suctioned onto the suction means by way of a simple temperature control.
In another embodiment, the control means is provided with dew point detection means for detecting a dew point.
In such an embodiment, there is detected the dew point in a changeable atmosphere, so that a desired dew condensation can be achieved at all times by controlling the apparatus on the basis of the detected dew point.
In another embodiment, the temperature changing means has a Peltier element.
Such an embodiment resorts to a Peltier element, having no movable parts or the like, for changing the temperature. Both the structure and the control of the apparatus can be made easier as a result.
In another embodiment, the suction means is provided in a vacuum chamber in which vacuum can be formed, the vacuum chamber being connected to a vacuum source.
In such an embodiment, condensed water ensures reliable suction while averting the influence of air, for instance, during bonding, thanks to the vacuum that is formed.
As explained above, therefore, the present invention succeeds in providing a suction holding apparatus and a suction holding method that allow suction-holding a substrate reliably irrespective of substrate type, with a simple and inexpensive structure.
Embodiments of the present invention (referred to hereinafter as embodiments) are explained in detail below with reference to accompanying drawings.
The constitution of a suction holding apparatus of the present embodiment (hereinafter, the present apparatus) will be explained first with reference to
Specifically, the present apparatus comprises, for instance, a vacuum chamber 1, a suction plate 2, a handling device 3, a lower plate 4, a temperature changing section 5, a control device 100, a dew point detecting section 6 and an input section 7, as illustrated in
The suction plate (suction means) 2 is a plate having, on the underside thereof, a suction surface 21 for suctioning a glass substrate P1. As the suction surface 21 there may be used, for instance, glass, a mirror-surface finished material or a polyimide. Preferably, the surface roughness Rmax is no greater than 0.1 μm. The present invention, however, is not limited to such materials or surface roughness.
The suction plate 2 is provided in such a manner that it can be raised and lowered within the vacuum chamber 1 by way of the lifting mechanism (driving means) not shown. The suction plate 2 has formed therein through-holes 22 through which there move below-described suction arms 31. A temperature changing section 5 (see
The handling device 3 comprises a plurality of suction arms 31 and vacuum pads 32. The suction arms 31 are provided so as to be capable of being raised and lowered by the lifting mechanism not shown. The vacuum pads 32 are provided at respective tips of the suction arms 31, and are connected to the vacuum source not shown. As a result, the glass substrate P1 is sucked onto the vacuum pads 32 when the suction arms 31 are lowered and pressure is reduced by the vacuum source. The lower plate 4 is provided in the lower container 12. The top face of the lower plate 4 constitutes a base section 41 on which there is placed a counter substrate P2 of identical size to that of the glass substrate P1.
The control device 100 is means for controlling, among others, the operation of the above-described vacuum source and lifting mechanism, as well as the temperature of the temperature changing section 5. As illustrated in
In the control device 100 there are set a determining unit 120 for dew point determination on the basis of the values detected by the dew point detecting section 6; a setting unit 110 for, by way of the input section 7, setting a predetermined temperature such that the temperature of the suction surface 21 is not higher than the dew point; and an instructing unit 130 four outputting an instruction signal to the temperature changing section 5 on the basis of determination by the determining unit 120 and the settings of the setting unit 110. Although not limited thereto, the set predetermined temperature can be set, for instance, to a temperature 10 to 20° C. below the dew point.
Such a control device 100 can be realized in, for instance, a dedicated electronic circuit or in a computer running a predetermined program. Therefore, a computer program for controlling the operation of the present device in accordance with the explanation below, and the recording medium in which the computer program is stored, constitute both an aspect of the present invention.
The suction and bonding procedure of a glass substrate in the present embodiment will be explained with reference to
The temperature changing section 5 sets the suction surface 21 to be cooled to a given temperature that is lower than the dew point temperature detected by the dew point detecting section 6, as described above, so that water vapor in the atmosphere condenses as a result on the suction surface 21. The glass substrate P1 is then conveyed into the vacuum chamber 1 that is open to the atmosphere. The top face of the glass substrate P1 is held, through vacuum suction, by the vacuum pads 32 of the suction arms 31 (step 302). The counter substrate P2, coated beforehand, by way of a dispenser, with a sealing agent and a liquid crystal, is placed meanwhile on the base section 41 of the lower plate 4.
Next, as illustrated in
As these members, having an extremely small surface roughness, are brought together into close contact, sandwiching a small amount of liquid therebetween, the liquid spreads very thinly between the members, whereupon the surface tension of the liquid gives rises to a strong suction force. The amount of liquid may be so small as to be undetectable to the naked eye.
As illustrated in
In this state, the suction plate 2 and the suction arms 31 are lowered to press and bond thereby the glass substrate P1 against the counter substrate P2, as illustrated in
The present embodiment, thus, requires no gripping part such as a mechanical chuck, and thus the counter substrate P2 and the glass substrate P1 of identical size can be bonded together. Also, no voltage needs to he applied to the glass substrate P1, and hence bonding can be carried out safely and reliably, regardless of substrate type and of the presence or absence of conductive films, circuits and the like.
The apparatus uses simply water condensed out of the atmosphere, by lowering the temperature, without any liquid being supplied to the suction surface 21. As a result, management of the apparatus is straightforward, while the cost of the apparatus can be reduced thanks to its simple structure. In particular, the water used for suction can be controlled by temperature management alone, while the cooling means used is a Peltier element. This makes for a simple and inexpensive system, little prone to malfunction, and easy to service.
Also, the apparatus utilizes small amounts water condensed on the suction surface 21. Homogeneous suction can thus be achieved naturally as a result even in case of large substrates. The apparatus can also be employed for products in which a substantial amount of residual liquid is best avoided.
The present invention is not limited to the above-described embodiment. The cooling temperature need only be such a temperature (for instance, a temperature not higher than the dew point) as to allow condensation on the suction surface. Accordingly, the cooling temperature is not limited to the temperature exemplified in the above embodiment. Detection of the dew point is not mandatory, and there may be set, as a default, a given temperature that should foreseeably make condensation possible.
When the atmosphere dew point is controlled to be substantially constant, for instance in a factory, a desired level of condensation can be confidently achieved when the apparatus is cooled down to a given temperature, even without detecting the dew point. Condensing water can also be controlled in concert with temperature control, by supplying a gas of desired humidity.
Bonding may be carried out in the atmosphere, or in an inert gas such as N2. Various techniques may be employed for releasing the suctioned substrate. The substrate may be released, for instance, by air blowing. The substrate may also be rendered easier to release through heating by the temperature changing means.
The substrates for which the present invention can be used can be freely selected in terms of size, shape, material, as well as presence or absence of conductive films or circuits. The pair of substrates to be bonded need not necessarily be of identical size. The invention is not limited to known standards such as those of liquid crystal panels, plasma display panels and organic EL panels, but can also be suitably employed for any standards that come into use in the future. The present invention, moreover, can be used not only for the above-described panels, but also for any kind of substrate that needs to be suction-held during a manufacturing operation.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-163938 | Jun 2006 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2007/000621 | 6/12/2007 | WO | 00 | 4/29/2009 |
