Method of and apparatus for laminating disc-shaped substrates

Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor

Reexamination Certificate

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Details

C156S238000, C156S540000, C156S541000

Reexamination Certificate

active

06200402

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of and an apparatus for laminating disc-shaped substrates, particularly to a method of integrally laminating two disc-shaped substrates using an adhesive sheet and an apparatus for carrying out the method, namely, an apparatus for bonding the adhesive sheet body onto two disc-shaped substrates.
2. Prior Art
Computers, especially personal computers have recently become popular, and the types of storage media for use therewith have increased. These types include magnetic discs, optical discs (e.g., CD-ROM), optical magnetic discs (e.g., MO), etc. The demand for optical discs has increases recently.
A DVD is one type of optical disc, and a disc-shaped substrate that is a single plate constituting the DVD is standardized to have a thickness of 0.6 mm, an outer diameter of 120 mm, an inner diameter of its central hole of 15 mm. Since such a thin disc-shaped substrate formed of a single plate is low in mechanical strength and is easily deformable, and in view of storage capacity, two disc-shaped substrates each having the same thickness (0.6 mm) are bonded onto each other to form an integrated substrate in a practical use thereof.
Such a high density storage disc (i.e. a DVD) is generally used as a laminated structure as set forth above, but is not used as a single plate. In such a case, it is necessary that both the upper and lower disc-shaped substrates be bonded onto each other.
A series of steps have been taken to manufacture an integrated storage disc (e.g. an optical disc) by bonding two disc-shaped substrates (see FIG.
22
), as in the following.
(1) a step of placing a lower disc-shaped substrate D
1
on a holding table
2
A;
(2) a step of coating an adhesive agent R made of UV cured resin to the lower disc-shaped substrate D
1
;
(3) a step of placing an upper disc-shaped substrate D
2
on the lower disc-shaped substrate D
1
to overlay the former on the latter;
(4) a step of rotating the holding table
2
A to develop the adhesive agent R interposed between the disc-shaped substrates D
1
and D
2
on the entire surfaces thereof; and
(5) a step of irradiating the developed adhesive agent made of UV cured resin with UV to cure the adhesive agent.
The storage disc is manufactured by the aforementioned steps, namely, the two disc-shaped substrates D
1
and D
2
are bonded onto each other to form a single integrated optical disc.
However in such a bonding method, since the adhesive agent is developed in a wider range by rotating the holding table, the adhesive agent is scattered outwardly due to centrifugal force. The periphery of the storage disc is made dirty or contaminated by the spray of the adhesive agent, or the adhesive agent is scattered and lost and hence the using efficiency of the adhesive agent is lowered.
Further, there is a problem that the thickness of the adhesive layer is not at all uniform. Still further, there is another problem that the number of manufacturing steps increases to increase the manufacturing cost because of the necessity of the step of irradiating adhesive agent with UV to cure the adhesive agent.
Accordingly, a method of bonding two disc-shaped substrates using an adhesive agent without requiring the developing step of the adhesive agent as set forth above has been studied. In the bonding method using an adhesive agent, the adhesive agent is bonded onto one of two disc-shaped substrates to be bonded, thereafter the other disc-shaped substrate is overlaid on the disc-shaped substrate onto which the adhesive agent is bonded.
An adhesive agent is generally used in a state where it is bonded onto a sheeting, i.e. an adhesive sheet body forming a base member, that is, a plurality of adhesive sheets or the adhesive agents are adhered to the adhesive sheet body. Accordingly, it is very ineffective to peel off the adhesive agent adhered to the adhesive sheet body one by one manually to bond or transfer it onto the lower disc-shaped substrate when two disc-shaped substrates are bonded onto each other. Further, fine air bubbles are liable to enter between the adhesive and the lower disc-shaped substrate when manually peeling off the adhesive agent. Still further, the bonding operation of an adhesive agent needs to be automated to incorporate the bonding operation of the adhesive agent to the disc-shaped substrates into the laminating lines of the disc-shaped substrates so as to produce a series of laminating lines which are sequentially controlled as a whole. That is, it is necessary to automatically bond the adhesive agent to the disc-shaped substrate to produce continuous laminating lines.
SUMMARY OF THE INVENTION
The present invention has been developed to solve the aforementioned problems. That is, it is an object of the invention to provide a method of laminating disc-shaped substrates capable of automatically bonding an adhesive agent to the disc-shaped substrate very effectively and continuously, and an apparatus for carrying out this method.
It is another object of the invention to provide a method of laminating disc-shaped substrates capable of preventing air from entering between the adhesive and one substrate when bonding the disc-shaped substrates by the adhesive agent, and an apparatus for carrying out this method.
The inventors of the present application endeavored themselves to study the aforementioned problems and have found that release paper can be peeled off from an adhesive agent bonded onto an adhesive sheet body, and the exposed adhesive agent can be bonded onto the lower disc-shaped substrate so as to sequentially bond the adhesive agent to the lower disc-shaped substrate, and thereafter has completed the invention.
A first aspect of the invention resides in a method of laminating disc-shaped substrates comprising preparing an adhesive sheet body S comprising a plurality of adhesive agents S
2
each covered with a release paper S
3
, peeling off the release paper S
3
from the adhesive sheet body S, positioning the adhesive sheet body S from which the release paper S
3
is peeled off over a lower disc-shaped substrate D
1
, pressing the adhesive sheet body S to allow the adhesive agent S
2
adhered to the lower surface of the adhesive sheet body S to bond or transfer onto a surface of the lower disc-shaped substrate D
1
, peeling off the adhesive sheet body S from the adhesive agent S
2
bonded onto the surface of the lower disc-shaped substrate D
1
, placing an upper disc-shaped substrate D
2
on the lower disc-shaped substrate D
1
, pressing the upper disc-shaped substrate D
2
against the lower disc-shaped substrate D
1
, thereby bonding the lower disc-shaped substrate D
1
and the upper disc-shaped substrate D
2
.
A second aspect of the invention resides in the method of laminating disc-shaped substrates comprising the steps of:
(1) preparing an adhesive sheet body S comprising a plurality of adhesive agents S
2
each covered with a release paper S
3
;
(2) peeling off the release paper S
3
from the adhesive sheet body S;
(3) positioning each adhesive agent S
2
of the adhesive sheet body S over a lower disc-shaped substrate D
1
using a positioning member;
(4) pressing the adhesive sheet body S from which the release paper S
3
is peeled off against the lower disc-shaped substrate D
1
to allow the adhesive agent S
2
adhered to the lower surface of the adhesive sheet body S to bond onto a surface of the lower substrate D
1
by moving a laminating member from one end of the lower disc-shaped substrate D
1
to the other end thereof;
(5) peeling off the adhesive sheet body S from the adhesive agent S
2
bonded onto the lower disc-shaped substrate D
1
using a peeling member;
(6) placing an upper disc-shaped substrate D
2
on the lower disc-shaped substrate D
1
; and
(7) pressing the upper disc-shaped substrate D
2
against the lower disc-shaped substrate D
1
to integrally laminate the disc-shaped substrates D
1
and D
2
.
A third aspect of the invention resides in the method of further including a step of collecting the release pape

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