JPS6150231A - Optical discs and their adhesive methods - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an optical disk for laser recording and a method of adhering the same.

Conventional configuration and its problems Laser recording disc (hereinafter referred to as optical disc)
is a large-capacity memory medium that can store more than 10,000 A4 documents on a disk with a diameter of less than 30c1n.
One bit corresponds to a small pit with a length of only about 1 μm. In addition, when writing and reading information, a laser beam narrowed to a diameter of around 1 μm is focused on a disk rotating at a high speed of 1,000 revolutions per minute or more, and the position is detected and the focus is adjusted. (It is executed), there is a very small amount of board glue, and there is a discrepancy in parallelism.

Deformations, scratches, foreign objects, etc. can also lead to signal errors. For this reason, the production of optical discs requires as much care as the production of semiconductors. As shown in Figure 2, optical discs have conventionally been used for the purpose of increasing reliability.
It has a structure in which a thin film 3 for laser recording is sandwiched between two transparent substrates 1.2. (However, Fig. 1 is a perspective view of an optical disc cut away, and below, part A of the cross section will be enlarged to explain the stacked state. Fig. 2 shows an example of a single-sided recording optical disc.) Therefore, the bonding process of bonding these two transparent substrates 1 and 2 together via the adhesive layer 4 is important, and this process often affects the yield and the reliability of the optical disc.

Traditionally, hot melt adhesives have been known as this bonding method, but since heat and pressure are applied at the same time, this method tends to cause warping, distortion, and bubbles on the board. Depending on the recording film, deterioration due to the influence of heat may occur, and in addition, peeling may occur due to a decrease in adhesive strength under high humidity.

Purpose of the Invention The present invention solves the above-mentioned drawbacks of the conventional bonding method, and enables the process of bonding optical discs, which requires high performance, to be carried out efficiently in a short time, and at the same time, does not require high temperatures in the process. Therefore, the object of the present invention is to provide an excellent adhesion method for optical discs that does not affect the recording film and provides strong adhesion so that peeling does not occur even when left under high humidity for a long time.

Structure of the Invention The round disk adhesion method of the present invention is based on the method of adhering two substrates to each other on the surface of each of the substrates to be bonded. The two components are applied separately, the adhesive-coated surfaces are overlapped, and then cured, thereby achieving the above-mentioned purpose.

DESCRIPTION OF EMBODIMENTS Before describing specific examples, the gist of the present invention will be explained with reference to the drawings. FIG. 3 shows a part of the cross section of the optical disk before it is bonded. That is, a layer 8 coated with one component of a two-component non-mixable adhesive is provided on a transparent substrate 5 on which a laser recording film 7 has been formed in advance, and on the other hand,
A layer 9 coated with one component of a two-component non-mixable adhesive is placed on the transparent substrate e that will be stored, and these two transparent substrates are bonded together and heated at room temperature or at about 700 to 80'Q for a short period of time. Allow time to cure. At this time, the two-component non-mixable adhesive refers to so-called second generation acrylic spreading adhesive, but is not limited to this, and after mixing, it cures quickly at room temperature or 70° to 80°C. Epoxy-based or silicon-based materials can also be applied to the present invention. The adhesive layers 8 and 9 can be applied by screen printing, spin coating (spin code), roll coating, spraying, kiss coating fx
An appropriate method may be adopted depending on the properties of the 8M agent.

In order to eliminate damage to the recording film when applying the adhesive, a thin protective film may be formed between the recording film 7 and the adhesive layer 8. In this case, spin coating is suitable for forming the protective film. There is. The optical disc is manufactured by inserting the transparent substrate from the side on which the recording film is not formed.
The recording film is changed using a focused laser beam, and reading is performed based on the difference in reflectance of the laser beam between the changed area and the unchanged area, so air bubbles may form in the adhesive near the recording film. If present, the reflectance may change and reading errors may occur. In order to prevent air bubbles from entering the adhesive, it is appropriate to carry out the bonding process under reduced pressure.

FIG. 4 shows a state diagram of the vacuum bonding process.

That is, in the vacuum container 1o, there is a shaft 13°1 that moves up and down.
A stand 11.12 connected to 4 is provided, on which a transparent substrate 11.12 already coated with adhesives 8 and 9 is attached,
The inside of the vacuum volume 1510 is reduced in pressure by the pump 15, and in this state the shafts 13 and 14 are moved to bond them together. The adhesive may be cured under reduced pressure or may be cured under normal pressure. By this method, a highly reliable adhesive state free of bubbles was obtained. Note that the degree of pressure reduction at this time is suitably about 20 Torr or less, and if it is more than this, bubbles may be mixed in.

(Example 1) 8I! Fig. 3 e (When manufacturing an optical disk with the cross-sectional state shown in Fig. 10 μ+ of one component of
On the other hand, on the transparent acrylic substrate c, a two-component non-mixable acrylic adhesive layer 9 was formed with a thickness of 1 μf using the spin cord method ζ.
The fl thickness is formed. These substrates 5 and 6 are placed parallel to each other with their central axes aligned, and the optical disk formed by the manufacturing method of the present invention has a small amount of initial glue and has the performance of not peeling off even if it is exposed to humidity for a long time. Indicated.

Effects of the Invention As described above, the present invention relates to a method for adhering optical discs that is highly reliable and has strong adhesive strength, and has the excellent feature that it can be bonded together in a short time using a relatively simple device.

[Brief explanation of the drawing]

Figure 1 is a cutaway perspective view of a completed optical disc, Figures 2, 3, and 6 are enlarged views of a portion of the cut surface, Figure 4 is a diagram showing the cross-sectional structure of the vacuum bonding device, and Figure 5. shows a cross-sectional view illustrating warpage of the disk. 1.2,5,6,17.18...Transparent substrate, 3
゜7.19...Optical recording film, 4, 8, 9, 21.2
2...Adhesive layer, 1o...Vacuum chamber, 1
1... lower pedestal, 12... upper pedestal,
13.14... Vertical axis, 16... Vacuum line, 16... Bonded disk, 20...
...Retention membrane. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3

Claims (3)

[Claims] (1) An optical disc having a cross-sectional structure in which a transparent substrate on which an optical recording film is formed and another transparent substrate are bonded together using a two-component non-mixable adhesive. (2) Apply the two components of the two-component non-mixable adhesive separately before mixing on the surface of each substrate of the optical disk board configured to bond two substrates together, and apply the adhesive. A method of adhering optical discs by overlapping their surfaces and then curing them. (3) A method for bonding optical disks according to claim 2, wherein two substrates coated with an adhesive are bonded under reduced pressure.