JP2005274882A - Inspection method for photosensitive coating layer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inspection method for a pinhole defect in a photosensitive resin layer to be used for a subtractive method. <P>SOLUTION: The method includes a first step of exposing a photosensitive coating layer without using a photomask after the photosensitive coating layer is laid on the surface of a substrate, and a second step of developing the exposed photosensitive coating layer. The photosensitive coating layer comprises a first film, a photosensitive resin and a second film. After the second step, a pinhole defect in the photosensitive coating layer is inspected. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for inspecting a photosensitive coating layer.

  With the recent increase in the density of electronic devices, the density and miniaturization of circuit boards such as flexible wiring boards used in the electronic equipment have been advanced.

  In order to satisfy these requirements in the subtractive method, there are processing techniques and materials. In the materials, processing accuracy and capability have been improved by thinning, and a photosensitive coating layer (hereinafter referred to as DFR) is also used. It corresponds to.

However, due to the thinning of the DFR, the adhesion to the substrate and the embedding property contribute to the product yield, and the DFR having a stable quality is essential. (For example, Patent Document 1)
Japanese Patent Laid-Open No. 07-074474

  An object of the present invention is to provide an inspection method for DFR used in a subtractive method.

Such an object is achieved by the present invention described in the following (1) to (4).
(1) A first step of laminating a photosensitive coating layer on the surface of a substrate and then exposing the photosensitive coating layer without using a photomask; and a second step of developing the exposed photosensitive coating layer A method for inspecting a photosensitive coating layer.
(2) The method for inspecting a photosensitive coating layer according to (1), wherein the photosensitive coating layer includes a first film, a photosensitive resin, and a second film.
(3) The method for inspecting a photosensitive coating layer according to (1) or (2), wherein the second film is peeled off when the photosensitive coating layer is laminated on a surface of a substrate.
(4) The method for inspecting a photosensitive coating layer according to any one of (1) to (3), wherein after the second step, the needle hole-like defect of the photosensitive coating layer is inspected.

  According to the present invention, it is possible to easily detect the air void generation rate of the DFR used in the subtractive method.

  Hereinafter, the DFR inspection method of the present invention will be described in detail based on preferred embodiments.

  FIG. 1 is a schematic view showing a cross section showing foreign matter in the second film and showing a concave dent in the photosensitive resin. FIG. 2 is a schematic view showing a cross section in which a photosensitive resin layer having a concave dent is laminated on a base material and an air pool in the concave portion is shown. FIG. 3 is a schematic view showing a cross section showing a state in which the photosensitive resin layer is exposed. FIG. 4 is a schematic view showing a cross-section showing a state in which the second film is removed after the exposure and development, and the concave portion becomes a needle hole-like defect after the exposure.

  As shown in FIG. 1, for example, a flexible copper-clad plate in which a copper foil is formed on one side or both sides of a substrate is used, and a pretreatment is performed for the purpose of improving the adhesion of the photosensitive coating layer and cleaning the copper foil surface. .

  The pretreatment is not particularly limited, and examples thereof include mechanical polishing and chemical polishing. A chemical polishing method that can uniformly treat the surface of the copper foil is desirable for the inspection of the fine portions.

  Although the copper foil thickness of a base material is not specifically limited, The thing of the thickness generally used should just be used. For example, there is no particular limitation such as an electrolytic copper foil of 8 to 35 μm or a rolled copper foil. Also, if you want to inspect needle hole-like defects, laminate a photosensitive coating layer on the surface of the substrate using an epoxy resin laminate, phenol resin laminate, polyester film, polyimide film, etc. instead of with copper foil. May be.

  Next, DFR is laminated on the surface of the base copper foil. Although it does not specifically limit as a lamination method, It is preferable to affix by the lamination method. When pasting on the copper foil surface, the second film is peeled off and the photosensitive resin is laminated on the copper foil surface.

  Lamination conditions are not particularly limited, but it is preferable to perform pressure bonding at a temperature of 90 to 120 ° C., a pressure of 0.2 to 0.4 MPa, and a speed of 1.0 to 3.0 m / min. The thickness of the DFR is preferably 5 to 60 μm used in the subtractive method, more preferably 5 to 40 μm, and further preferably 5 to 15 μm used for the purpose of forming a fine pattern.

Next, exposure is performed on the entire surface of the DFR, but since it is an evaluation of the DFR alone, it is preferable that no photomask or the like be interposed between the exposure light source and the DFR. Although exposure conditions are not particularly limited, it is preferable to expose with an integrated light quantity of 50 to 150 mJ / _cm ² .

  Examples of the exposure means include an exposure apparatus (contact type, projection type, etc.), an ultraviolet irradiation apparatus, etc., but an exposure apparatus that is a DFR target and is used in a process using a subtractive method is preferable.

  Next, development processing is performed to inspect the surface state of the DFR.

  The development conditions are not particularly limited, but a 0.9 to 1.1% sodium carbonate aqueous solution, a temperature of 28 to 30 ° C., and a processing time of 10 to 50 seconds are preferable. In addition, the surface state inspection is preferably 10 to 40 times microscope observation for the purpose of observing fine DFR air voids.

Hereinafter, although it demonstrates in detail based on the Example and comparative example of this invention, this invention is not limited to this.
(Example 1)
DFR used for forming products with a disconnection system (disconnection, chipping) defect rate of 34% influenced by DFR quality was inspected for DFR after passing through substrate pretreatment, DFR lamination, exposure, and development processes. As a result, 32 DFR deficiencies of 30-50 μm were observed in the 50 × 50 mm range.

As a result of observing the polyethylene film which is a protective film of the DFR, 27 gels (fish eyes) of 30 to 50 μm were observed in a range of 50 × 50 mm, and the quality abnormality of the polyethylene film was found.
(Comparative Example 1)
The same procedure as in Example 1 was performed except for the quality of the polyethylene film, which is a DFR protective film.

  As a result of examining the state of the obtained DFR, no lack of DFR was observed in the range of 50 × 50 mm.

  As a result of forming a product using the DFR, the disconnection system (disconnection, chipping) defect rate influenced by the DFR quality was improved to less than 1%.

  From the above results, it was clear that the quality of the polyethylene film as a protective film contributes to fine air voids particularly in the thin type DFR, and the quality standards in DFR production were clarified and the DFR quality was improved.

The outline which shows the section which had a foreign object in the 2nd film and showed the concave dent in photosensitive resin. Schematic which shows the cross section which laminated | stacked the photosensitive resin layer which has a concave dent on a base material, and showed the air pocket of the recessed part. Schematic which shows the cross section which showed the state which exposed the photosensitive resin layer. Schematic which shows the cross section which showed the state by which the 2nd film was removed after exposure and the recessed part became a needle hole shape defect | deletion after image development.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st film 2 Photosensitive resin 3 2nd film 4 Gel (fish eye)
10 Photosensitive resin layer (DFR)
5 Copper foil 6 Base material 20 Flexible copper-clad plate 7 Air void 8 Needle hole-like defect

Claims (4)

  After laminating the photosensitive coating layer on the surface of the substrate, the method includes a first step of exposing the photosensitive coating layer without using a photomask, and a second step of developing the exposed photosensitive coating layer. Inspection method of photosensitive coating layer.   The method for inspecting a photosensitive coating layer according to claim 1, wherein the photosensitive coating layer comprises a first film, a photosensitive resin, and a second film.   The method for inspecting a photosensitive coating layer according to claim 2, wherein the second film is peeled off when the photosensitive coating layer is laminated on a surface of a substrate.   The method for inspecting a photosensitive coating layer according to any one of claims 1 to 3, wherein after the second step, a needle-hole-like defect in the photosensitive coating layer is inspected.

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