Device for drying substrates

Details Device for drying substrates Device for drying substrates

1999-11-23

2001-01-09

Gravini, Stephen (Department: 3749)

Drying and gas or vapor contact with solids

Material treated by electromagnetic energy

Ultraviolet energy

C034S278000, C034S066000, C034S189000, C034S195000

Reexamination Certificate

active

06170169

ABSTRACT:

BACKGROUND OF THE INVENTION
The invention relates to a device for drying substrate disks by irradiation with ultraviolet light, wherein during the irradiation process a glass plate rests on the substrate disk.
Such drying devices are especially employed for the manufacture of compact disks or CDs, mini-disks, magneto-optical disks, CD-ROMs, CD-Rs, photo-CDs and/or video disks, and/or digital video disks (DVDs). Especially for the manufacture of substrate disks which are comprised of two partial substrates to be glued together, the glass plates are placed during the drying process onto the substrate disks in order to prevent that the substrate during the drying process will buckle or lose its planar shape. The term drying is to include also the curing of adhesives with which, for example, two substrates are glued to form a substrate disk. The substrate disks to be dried are conventionally positioned on a turntable which rotates in a cycled manner and transports the substrate disks into the drying area of the drying device. Before the substrate disks enter the drying area, the glass plates are placed by a glass plate handling device onto the substrate disks and are removed therefrom after the drying process when the substrate disks have been rotated out of the drying device. By placing the glass plates onto the substrate disks with the aid of a glass plate handling device, it cannot be prevented that non-uniform pressure is applied to the substrate disks. This changes the layer of adhesive positioned between the substrates to be glued which can be changed by pressure in the not yet dried or not yet cured state with respect to its layer thickness. It was found that this causes high reject rates and also considerably impairs the quality of the finished substrate disks.
SUMMARY OF THE INVENTION
The invention has the object to provide a drying device of the aforementioned kind which with simple technical means and simple manipulation of the device provides for reduced reject rates and an improved quality of the finished substrate disks.
This object is inventively solved by a liftable and lowerable upper part which lowers the glass plate onto the substrate disk positioned on a lower part. The placement of the glass plate is performed inventively in the drying device itself so that the time period between placement of the glass plate and start of the drying process is very short. This is very important in regard to the reject rate and the quality of the substrate disk to be manufactured because the adhesive that has been applied uniformly between the two substrates to be glued with high device-technological expenditure will lose its uniform distribution causing variations in the adhesive layer thickness between the substrates to be glued. This results in rejects and reduced quality of the substrate disks. For the uniform application of adhesive layers before the drying process, high expenditures are required. In order not to lose the advantages that can be achieved with a uniform adhesive layer, the inventive device allows to achieve a very short time period between placement of the glass plate and the beginning of the drying process.
According to a further very advantageous embodiment of the invention, the upper part has a glass plate holding device which, upon lowering of the upper part for placement of the glass plate onto the substrate, will drop below it. In this manner the glass plate will be placed onto the substrate disk without additional or non-uniform pressure application so that the pressure of the glass plate across the entire substrate disk surface is very uniform because only the own weight of the glass plate will effect the pressure application. In this manner the aforementioned uniform adhesive layer will be maintained substantially over the entire substrate disk surface area.
Preferably, the glass plate holding device has securing brackets on which edge portions of the glass plate will rest in the lifted state of the upper part. The apparatus configuration for placement of the glass plate onto the substrate disk is thus very simple and realized with especially simple means because the position of the securing brackets and thus the securing and lowering of the glass plate can be adjusted with simple means.
The securing brackets are preferably reflective surfaces, for example, by being polished to high luster. Accordingly, they reflect the ultraviolet radiation especially in the area of the substrate disk to be dried in a suitable manner so that the critical edge drying process is thus improved and accelerated. Since the securing brackets after placement of the glass plate onto the substrate disk are positioned below the substrate disk, the positioning of these securing brackets below the substrate disk makes it possible that the ultraviolet light impinging from above can also be directed onto the lower edge portion of the substrate disk.
According to a further very advantageous embodiment of the invention, the glass plate delimits an irradiation chamber for the substrate disk in the upward direction. The glass plate thus forms a closure wall for the irradiation chamber which is especially advantageous when the drying device, according to a further embodiment, has a gas inlet device for introducing a gas to displace the air in the treatment chamber, for example, for introducing nitrogen. The displacement of the air contained in the treatment chamber prevents the oxygen contained therein from reacting to oxygen peroxide by exposure to the intensive UV radiation. Oxygen peroxide strongly absorbs UV radiation and will hinder and delay the drying process. With the inventive liftable and lowerable upper part of the drying device it is possible to place the glass plate not only onto the substrate disk but, alternatively, also at a desired spacing from the substrate disk so that between glass disk and glass plate the air contained therebetween can be displaced by the introduced gas. The drying process can thus be improved or accelerated over the entire surface area of the substrate disk. It is also possible with the inventive device to change quickly and without additional expenditure the type of drying process for the substrate disk, i.e., to place the glass plate completely onto the substrate disk or to maintain the glass plate at a selected spacing above the substrate disk during the drying process.
According to a further advantageous embodiment of the invention spacers are provided between the glass plate and the substrate. The spacer can be provided on the glass plate holding device so that the glass plate cannot be placed onto the substrate disk. Because of the spacer which has a desired thickness corresponding to the desired spacing between glass plate and substrate disk, it is thus also possible, simply by placing the spacers onto the glass plate holding device, to change the inventive device from the operational mode with contacting glass plate to the operational mode with intermediate space between the glass plate and the substrate disk.
According to an advantageous embodiment of the invention, a rotating device is provided which rotates or pivots the upper part in its lifted position into and out of the irradiation chamber. The rotation device is preferably integrated into a lifting device for lifting and lowering the upper part or is combined with a lifting device so that the drive device for the glass plate handling device is compact and of a simple configuration.
Preferably, the rotation device has a turntable with multiple upper parts. It is thus possible to transport the glass plates heated during the previous drying process into a cooling station provided according to a further embodiment of the invention. The cooling station thus cools the glass plates not positioned within the irradiation chamber for the drying process so that they will reach a similar temperature as that of the substrate disk for placement onto a substrate disk for a further drying process. When the temperature difference between the deposited glass plate and the substrate disk is substan

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