JP2008041165A - Stamper inspecting adhesive sheet and stamper inspecting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical disk capable of efficiently recording a visible image having high contrast by the use of laser light. <P>SOLUTION: In a stamper inspecting adhesive sheet, where an adhesive layer containing an adhesive agent is formed on an optical film, the adhesive agent has 3 (N/25 mm) or smaller for the adhesive force. In a stamper inspecting method, with which a stamper is irradiated with laser light, to perform inspection by using its reflected light, the stamper surface to be inspected to which the stamper inspecting adhesive sheet is stuck is irradiated with the laser light. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a stamper inspection method for optical discs and an adhesive sheet for stamper inspection.

  Blu-ray discs perform recording and reproduction by forming a cover layer having a thickness of 0.1 mm on a substrate and focusing the recording surface. In general, in order to focus on the stamper surface when inspecting a groove signal or the like of the stamper, it is necessary to provide a cover layer having a thickness of 0.1 mm on the stamper surface or to manufacture a dedicated pickup.

  Designing a special pickup for a blue laser is expensive and impractical, and a commercially available stamper inspection machine is also equipped with the same pickup as a recording / reproducing machine for a disc.

  As a method of providing a cover layer on a disk, there are a method of bonding a sheet provided with an adhesive layer in advance, a method of bonding a sheet with an adhesive, and a method of applying 0.1 mm only with a UV curable resin. In view of the fact that a large-scale apparatus such as a spin coater or a UV irradiation apparatus is not required, it is considered that a method of providing a cover layer (adhesive sheet) on a stamper is simple and effective.

Various methods are known as stamper inspection methods (see, for example, Patent Document 1). Under such circumstances, in the case of a Blu-ray disc, in consideration of providing a cover layer, it is considered to perform an inspection by providing an adhesive sheet having the same thickness as the cover layer. However, in the case of disc stamper inspection, it is necessary to remove the cover layer and mold the substrate after the inspection is completed. However, with an ordinary disc adhesive sheet, the adhesive component tends to remain on the stamper surface, causing dust and dirt. It caused dust to adhere.
JP-A-6-259817

  The present invention aims to solve the above problems. That is, an object of the present invention is to provide a stamper inspection pressure-sensitive adhesive sheet and a stamper inspection method that can maintain a clean surface even after inspection and reduce signal fluctuations of a molded substrate.

  As a result of intensive studies to solve the above problems, the present inventor has conceived the following present invention and found that the problems can be solved.

  That is, the present invention is an adhesive sheet for stamper inspection in which an adhesive layer containing an adhesive is formed on an optical film, and the adhesive strength of the adhesive is 3 (N / 25 mm) or less. This is a pressure-sensitive adhesive sheet for stamper inspection.

  Further, the present invention is a stamper inspection method for irradiating a stamper with laser light and inspecting with the reflected light. The stamper inspection adhesive sheet according to claim 1 is bonded to a surface to be inspected of the stamper. The stamper inspection method is characterized by irradiating the laser beam. In the said inspection method, it is preferable to use a roller for pasting together the said stamper test | inspection adhesive sheet, and to make the pressing pressure of the said roller into actual pressure 100kPa-4MPa. Here, “actual pressure” refers to an average pressure when the pressure applied to the roller (cylinder pressure) is uniformly received with a deformation width of 1 mm due to the elasticity of the roller.

  According to the present invention, it is possible to provide a stamper inspection pressure-sensitive adhesive sheet and a stamper inspection method that can maintain a clean surface even after inspection and reduce signal fluctuations of a molded substrate.

[Pressure-sensitive adhesive sheet for stamper inspection]
In the pressure-sensitive adhesive sheet for stamper inspection of the present invention, an adhesive layer containing an adhesive is formed on an optical film. And the adhesive force of an adhesive is 3 (N / 25mm) or less.

  The stamper inspection pressure-sensitive adhesive sheet is used when a stamper is inspected by a known stamper inspection machine. For example, the present invention can be applied to a stamper that cannot be directly converted by a conventional apparatus, such as a stamper for forming a substrate of a Blu-ray disc.

  Simply attaching the adhesive sheet to the surface to be inspected of the stamper creates a gap in the groove of the stamper. On the other hand, if an adhesive sheet coated with a highly adhesive adhesive is attached to a stamper, a part of the adhesive remains on the stamper when the adhesive sheet is peeled off after inspection, causing dirt and defects. turn into.

  In view of the above, in the present invention, the adhesive strength of the adhesive is 3 (N / 25 mm) or less. That is, when the adhesive strength exceeds 3 (N / 25 mm), the adhesive remains in the stamper groove. The adhesive force is preferably 0 to 1 (N / 25 mm). Here, “adhesive strength” is measured as follows. First, as shown in FIG. 1, a stamper inspection pressure-sensitive adhesive sheet 4 cut to a width of 25 mm × 200 mm is attached to the same plate 2 as the stamper material (for example, Ni). At this time, the stamper inspection pressure-sensitive adhesive sheet 4 and the plate 2 are brought into close contact with each other by rubbing at a pressure higher than that actually applied by the stamper. Leave at room temperature (23 ° C., 50%) for 24 hours, then peel off 50 mm from the edge, turn back 180 °, pull the edge with a tensile tester 6 at a speed of 10 mm / min, and peel off the adhesive sheet from the Ni plate Measure the load necessary to measure the adhesive strength.

  As the pressure-sensitive adhesive, those having an adhesive strength of 3 N / 25 mm or less are used. As an example thereof, an acrylic pressure-sensitive adhesive is used, the main component is a copolymer of acrylic acid ester, and the constituent monomer is ethyl acrylate, n-Butyl acrylate, methyl acrylate, methyl methacrylate, vinyl acetate, acrylic acid, methacrylic acid, etc. Is mentioned. The adhesive strength can be controlled by the molecular weight of the main component, the type and ratio of the copolymer, and the curing agent. Further, the adhesive force can be controlled by adding an acrylic component having a lower molecular weight than that of the main copolymer as a plasticizer.

  As the optical film, a polycarbonate film, triacetate cellulose, a cyclic polyolefin film, or the like can be used. The thickness of the pressure-sensitive adhesive layer made of the pressure-sensitive adhesive is preferably 5 to 50 μm. The thickness of the optical film is preferably 50 to 95 μm.

[Stamper inspection method]
The stamper inspection method of the present invention is a method in which a laser beam is irradiated onto a stamper and the reflected light is used for inspection, and the above-mentioned stamper inspection pressure-sensitive adhesive sheet of the present invention is bonded to the surface to be inspected of the stamper. Is performed.

  The stamper inspection method can be performed using a known optical disc stamper inspection machine. A method for inspecting reproduction characteristics such as an HF signal of a pit formed on an optical disc stamper and a tracking error signal of a groove will be described with reference to FIG. Note that FIG. 2 is exaggerated for easy understanding.

  The optical disk stamper 10 to be measured is attached to the rotary table 12, and while being rotated by the spindle motor 14, the optical head 16 irradiates the optical disk stamper 10 with a laser beam through the stamper inspection adhesive sheet 30, and detects the amount of reflected light. To do. In the optical head 16, diffused light is emitted from the semiconductor laser 18, converted into parallel light by the collimator lens 20, transmitted through the beam splitter 22, condensed by the objective lens 24, and reaches the signal surface of the optical disc stamper 10.

  The stamper inspection pressure-sensitive adhesive sheet 30 is the pressure-sensitive adhesive sheet of the present invention described above, and by providing the pressure-sensitive adhesive sheet, it is possible to perform inspection assuming the formation of a substrate for a Blu-ray disc. As a result, a clean surface can be maintained even after inspection, and signal fluctuations of the molded substrate can be reduced.

  The laser spot irradiated on the signal surface of the optical disc stamper 10 is reflected while being modulated by the shape of the pits or grooves, is again transmitted through the stamper inspection adhesive sheet 30 and the objective lens 24, is reflected by the beam splitter 22, and is a photodiode. At 28, the amount of light is detected. The incident surface of the photodiode 28 is divided into two regions, and each channel performs independent current-voltage conversion and amplification to form two channels.

  The HF signal is obtained by adding the output signals of the respective channels while preserving the high band. The tracking error signal is obtained by subtracting the output signals of these two channels. As the objective lens 24 used here, one having a design specification equivalent to that mounted on the optical disk drive can be used.

  Here, examples of the bonding of the stamper inspection pressure-sensitive adhesive sheet include vacuum processing and processing using a roller. In consideration of productivity such as simplicity of the apparatus and cycle time, it is preferable to use a roller and set the pressing pressure of the roller to an actual pressure of 100 kPa to 4 MPa.

  By setting the pressing pressure of the roller to an actual pressure of 100 kPa to 4 MPa, mixing of bubbles can be eliminated and generation of wrinkles can be prevented. The pressing pressure of the roller is more preferably 200 kPa to 2 MPa.

(Example 1)
A stamper having a spiral groove with a track pitch of 320 nm and a depth of 45 nm was placed. The pressure-sensitive adhesive layer of the stamper inspection pressure-sensitive adhesive sheet was bonded to the surface of the stamper on which the groove was formed, using a roller. The roller pressing pressure was 500 KPa. The pressure-sensitive adhesive that constitutes the pressure-sensitive adhesive layer is butyl methacrylate / tolylene diisocyanate, and low-molecular (Mn = 3000) acrylic is added to reduce the adhesive strength to 0 (N / 25 mm). there were.

  The stamper after pasting the sheets was attached to a stamper inspection machine (laser wavelength 405 nm, NA 0.85 lens pickup mounted) manufactured by Pulstec Corporation, and the stamper was inspected. Specifically, the stamper surface was irradiated with a laser, and a signal variation due to the reflected light was detected to inspect the defect. Further, after the inspection, the cover sheet was peeled off, and the presence or absence of a visible deposit (visible residue) after peeling of the adhesive sheet was confirmed. Using the stamper, a 1.1 mm substrate for Blu-ray was injection molded (manufactured by Teijin Kasei's polycarbonate brand name Panlite AD5503. Further, Ag was sputtered to form a reflective layer having a thickness of 100 nm, and then The above cover sheet was laminated, and the signal fluctuation of the molded substrate was measured, and the results are shown in Table 1 below.

(Examples 2-5 and Comparative Examples 1-3)
As shown in Table 1 below, the pressure applied by the roller or the main monomer component of the adhesive layer is changed (2-ethylhexyl acrylate / tolylene diisocyanate type, low molecular acrylic component added amount ↓). The stamper was inspected and evaluated in the same manner as in Example 1 except that the force was changed. The results are shown in Table 1 below.

  From Table 1 above, in Examples 4 and 5, there are some problems in the items that can be inspected, but there is no problem in practical use. Moreover, in the Example, it was confirmed that the clean surface was maintained even after the inspection, and the signal fluctuation of the molded substrate was good at 4% or less.

It is explanatory drawing explaining the measuring method of the adhesive force of the adhesive sheet for stamper inspection. It is principal part explanatory drawing for demonstrating a stamper inspection machine.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Optical disk stamper 12 ... Rotary table 14 ... Spindle motor 16 ... Optical head 18 ... Semiconductor laser 20 ... Collimating lens 22 ... Beam splitter 24 ... Objective lens 28 ... Photodiode 30 ... Stamp inspection adhesive sheet

Claims (3)

An adhesive sheet for stamper inspection in which an adhesive layer containing an adhesive is formed on an optical film,
A pressure-sensitive adhesive sheet for stamper inspection, wherein the pressure-sensitive adhesive has an adhesive strength of 3 (N / 25 mm) or less. A stamper inspection method for irradiating a stamper with laser light and inspecting with the reflected light,
A stamper inspection method, wherein the stamper inspection adhesive sheet according to claim 1 is bonded to a surface to be inspected of the stamper, and the laser light is irradiated. The stamper inspection method according to claim 2, wherein a roller is used for bonding the stamper inspection pressure-sensitive adhesive sheet, and the pressing pressure of the roller is set to an actual pressure of 100 kPa to 4 MPa.

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