JP2882953B2 - Drift film resist - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dry photoresist, and more particularly, to a dry photoresist which is easy to manufacture and handle and is particularly useful for manufacturing a printed wiring board.

[0002]

2. Description of the Related Art Printed wiring boards, one of the main components in the electronics industry, are made of dry photoresist (DFR).
Is often manufactured by a method of forming a circuit on a substrate by a photographic method. This DFR conventionally has a thickness of 1
A photoresist layer 3 of 5 to 50 μm is sandwiched between a biaxially stretched polyethylene terephthalate film of 16 to 25 μm as a base film 1 and a polyethylene film of 30 to 40 μm as a protective film 2 (FIG. 2). ), Usually 1m or more in width,
Those having a length of 120 to 150 m are wound in a roll shape and are traded.

[0003] In the production of a printed wiring board, the DFR is used to thermally compress the photoresist layer side to a copper foil substrate using a laminator device while peeling off a protective film. After that, it is common practice to expose a base film by placing a pattern mask thereon, and then peel off the base film and develop. Since ultraviolet light (UV light) is usually used for exposure, a biaxially stretched polyethylene terephthalate film having excellent UV transmittance, high transparency and a flat surface is used for a base film, and an inflation stretching method is used for a protective film. A formed medium-density polyethylene film is used. This protective film not only protects the photoresist layer (photocurable resin layer), but also has a function of preventing the back surface of the base film from sticking to the photoresist layer when the DFR is wound into a roll.

[0004] In manufacturing a printed wiring board, the DFR is slit with a protective film provided in accordance with the standard of a copper foil substrate. For this reason, the peeled protective film or base film cannot be reused repeatedly. The thickness of the protective film is generally thicker than that of the base film, and there is a problem that the volume discarded as waste becomes larger than that of the base film.

[0005] From such a point, it is ideal that the DFR is to reduce the thickness of the transparent base film as much as possible to enhance the UV exposure efficiency, and also to make the protective film thinner to make the roll-shaped winding compact. The width of rolls is increasing, and the thickness of the base film is required to be 20 to 25 μm in order to stably produce high-quality DFR in a width of 1.6 m or more, and the total thickness of the base film and the protective film is about 50 μm. The configuration is taken.

[0006]

DISCLOSURE OF THE INVENTION The present invention has intensively studied to produce a dry film resist (DFR) which eliminates the step of providing a protective film on a photoresist layer and contributes to reduction of industrial waste. As a result, the present invention has been achieved.

[0007]

That is, the present invention provides a method for forming a photoresist layer on one surface of a transparent base film.
And a composite film in which a release layer 2 of an olefin-based resin is laminated on the other surface of the base film with respect to the photoresist layer, and the composite film is wound into a roll. A dry film resist characterized in that the photoresist layer is protected by a release layer. FIG. 1 shows the structure of the composite film.

As the transparent base film in the present invention, a biaxially stretched polyester film, particularly a biaxially stretched polyethylene terephthalate film is preferably used.
The thickness of this film is preferably 15 to 30 μm, more preferably 20 to 25 μm.

In the present invention, as a photoresist layer applied on one surface of the transparent base film, a conventionally used photoresist layer can be applied. For example, a negative-type alkaline developing photoresist is composed of, as a basic composition, 50% or more of a binder polymer, a photopolymerizable monomer, a photopolymerization initiator, and other additives (a dye, a thermal polymerization inhibitor, and the like). .

The binder polymer contains an acid group (carboxyl group) in the polymer in order to impart alkali developability.
It is preferable to specifically include a copolymer containing methyl methacrylate as a main component and copolymerizing at least one of copolymer components such as various (meth) acrylates, styrene, acrylonitrile, and (meth) acrylic acid. Is done. The binder polymer has the function of giving the photoresist a film forming ability and imparting tackiness to the resist surface. This tackiness imparts appropriate adhesion to the release layer, and has an effect of keeping the peeling force (180 °, low-speed peeling) at 20 to 30 g / inch, for example.

The photopolymerizable monomer is not particularly limited as long as it is entangled with the binder polymer and undergoes photopolymerization (crosslinking and curing) and becomes insoluble in a developer, but a (meth) acryloyl group-containing polyfunctional monomer is preferred. Can be
This photopolymerizable monomer does not contribute to tackiness.

Examples of the photopolymerization initiator include benzoin, diazonium compounds, halogen compounds and the like.

In the present invention, the application of the photoresist layer can be carried out by a conventionally employed method.

In the present invention, the release layer to be laminated on the other surface of the transparent base film is preferably laminated on the surface of the transparent base film on which a photoresist layer has not yet been applied. As a result, the steps after the application of the photoresist layer can be greatly rationalized.

This release layer preferably has the following characteristics. (1) It has releasability from the photoresist layer (photo-curable resin layer) and has a peeling force (180 °, low-speed peeling) of 20 to 3
In the range of 0 g / inch. (2) The generation of static electricity at the time of peeling is small, and dust and foreign matter are not attached. (3) It has heat resistance and solvent resistance enough to withstand the drying treatment after the application of the photoresist layer. As the heat resistance, for example, it is preferable to withstand drying treatment at 120 ° C. for 1 minute. (4) It is preferable to have transparency that transmits ultraviolet light (UV light) at the same level as a base film. (5) It is preferable to have air bubble elimination property, for example, it is preferable that the surface of the release layer has irregularities of about 0.1 to 10 μm.

The lamination of the release layer is different between the mode in which the release layer and the base film are integrated at the time of exposure and the mode in which the release layer is separated from the base film. It is preferable to laminate by a co-extrusion method, and in the latter case, it is preferable to laminate by an extrusion lamination method. Among these, it is particularly preferable to laminate by an extrusion lamination method.

As the coating agent used in the coating method, a coating agent having a release level comparable to that of a medium-density polyethylene film currently used as a protective film for DFR is preferred. Particularly preferred are release agents and olefin-based resins modified with. Specific examples of the former include those obtained by modifying a functional group of PVA (polyvinyl alcohol) or polyethyleneimine with a higher fatty acid such as stearic acid, and these are preferable not only from the viewpoint of releasability but also from the viewpoint of transparency. These can be used to prepare a coating solution using an organic solvent such as toluene, tetrahydrofuran, cyclohexanone, or the like. A specific example of the latter is low-density polyethylene. This can be dispersed in an aqueous medium in the form of fine particles to prepare a coating liquid. As the aqueous dispersion, Chemipearl-M200 (manufactured by Mitsui Petrochemical Co., Ltd.) can be used. Further, the coating solution can be prepared by dissolving in an organic solvent such as tetrahydrofuran or cyclohexanone.

However, a silicone-based release agent widely known as a release agent deteriorates the properties of the photoresist layer, and thus is not preferably used as the release agent of the present invention.

The thickness of the release layer formed by the coating method is preferably 0.05 μm or more, and is preferably 1 μm or less, depending on the transparency of the release layer. In addition, in order to enhance the adhesion between the release layer and the base film during coating, it is preferable that the base film is subjected to an easy-adhesion primer treatment. It is preferable to use

The release resin used in the coextrusion method includes:
Olefin resins, especially polypropylene and medium density polyethylene are preferred. Coextrusion can be performed by a conventionally known method.

The release layer formed by the co-extrusion method is stretched by stretching the base film, particularly by biaxial stretching, to form a thin stretched film layer. This film layer is strongly adhered to the base film by the stretching treatment, and cannot be substantially removed again. Therefore, it is preferable that the thickness of the release layer be the same as that of the coating method. If the thickness is too large, the transparency is lowered and the UV light transmittance is lowered, which is not preferable.

The release resin used in the extrusion laminating method may be the same as the release resin used in the coextrusion method. Extrusion laminates are conventionally known.

The release layer formed by the extrusion lamination method includes:
This is a non-stretched film layer which is not usually subjected to a stretching treatment. This film layer has a weak adhesion to the base film, and has a peeling force (180 °, low-speed peeling) for a biaxially stretched polyethylene terephthalate film, for example, in the range of 5 to 20 g / inch. This peeling force does not cause the release layer to peel off from the base film in normal handling, for example, applying a photoresist layer on the surface of the base film,
There is no peeling during the process of winding the DFR into a roll.
This peeling force can be adjusted by adjusting the melt extrusion temperature of the release resin, and when this temperature is lowered, the peeling force is reduced, and when it is increased, the peeling force is increased.
This peeling force can also be adjusted by subjecting the surface of the base film to a primer release treatment.

The thickness of the release layer formed by the extrusion lamination method is smaller than that of the base film. In particular, it is preferable that the total thickness of the base film and the release layer is 50 μm or less, and the thickness of the release layer is less than １ ／ of the total thickness. Preferably, the thickness is 10 μm or more.

Since the adhesion between the base film and the release layer is generally smaller than the adhesion between the photoresist layer and the release layer, as described above, the DF is not used.
When the R is unwound, it can be unwound while separating between the base film and the release layer, and can be unwound while separating between the photoresist layer and the release layer. In the former case, the delivered DFR has the same three-layer structure as the current product, and has the advantage that the photoresist layer is protected by the release layer from which the photoresist layer has been peeled off. This has the advantage that foreign matter and the like do not adhere. Even in this case, since the release layer is thinner than the conventional protective film, the effect of reducing the amount and volume of the waste film can be achieved.

In the present invention, a composite film in which a photoresist layer is coated on one surface of a transparent base film and a release layer is laminated on the other surface of the base film is wound into a roll to separate the photoresist layer. Although it is necessary to protect the mold layer by closely contacting it, it is preferable that air bubbles are not trapped between the photoresist layer and the release layer. In particular, since the release layer formed by a coating method or a co-extrusion method has a small thickness and has a smooth surface, it is difficult to remove trapped air bubbles. Therefore, it is preferable that air bubbles are not trapped. On the other hand, since the release layer formed by the extrusion lamination method has a large thickness and a rough surface, it is relatively easy to remove trapped air bubbles. This is because the gas barrier property of olefin resin, especially polyethylene is low and air is easy to escape, and air bubbles are removed from the roll edge through the interface between the photoresist layer and the release layer due to the fine irregularities on the surface. It depends. As means for forming fine irregularities on the release layer, embossing is preferably mentioned.
The thickness is preferably 1 to 10 μm. This embossing can be performed by cooling the extruded and laminated resin with an embossing roll. By changing the emboss pattern, the roughness of the surface irregularities can be adjusted.

The release layer is preferably laminated by an extrusion lamination method from the above-mentioned exclusion of air bubbles.

When the release layer is peeled off from the composite film of the present invention, dust in the air may adhere to the transparent base film due to static electricity. For the purpose of preventing this adhesion, antistatic treatment is applied to the transparent base film. It is preferable to apply. A conventionally known processing method can be applied to this processing.

[0029]

EXAMPLES The present invention will be further described below with reference to examples.

[0030]

Example 1 Using a transparent biaxially stretched polyethylene terephthalate film having a thickness of 25 μm, a medium-density polyethylene having a thickness of 15 μm was laminated on one surface of the film by extrusion lamination. During the cooling of the polyethylene, the polyethylene was applied to an embossing roll to give a 0.4 μm satin-like emboss on the surface of the release layer. Next, a photoresist layer having a thickness of 20 μm was applied on the other surface of the polyethylene terephthalate film. The obtained composite film was roll-wound so that the release layer and the photoresist layer were in close contact with each other.

In this roll winding, the peeling force between the release layer and the photoresist layer was about 20 g / inch, and the unwinding was good. The removal of air bubbles between the photoresist layer and the release layer was good.

[0032]

Example 2 A transparent biaxially stretched polyethylene terephthalate film having a thickness of 25 μm was used, and a polyethyleneimine alkyl modified product (RP manufactured by Nippon Shokubai Chemical Co., Ltd.)
-10) was dissolved in a mixed solvent of methyl ethyl ketone / toluene, and a release agent coating liquid having a solid concentration of 1% was applied at 10 g / m ^2.
Coated and dried. The release layer thickness is 0.1 μm. Next, in the same manner as in Example 1, a photoresist layer having a thickness of 20 μm was applied to the other surface of the polyethylene terephthalate film. The obtained composite film was roll-wound so that the release layer and the photoresist layer were in close contact with each other.

In this roll winding, the peeling force between the release layer and the photoresist layer was about 20 g / inch, and the unwinding was good.

[0034]

According to the present invention, it is possible to omit the step of providing a protective film on a photoresist layer and to provide a dry film resist which contributes to reduction of industrial waste.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing the configuration of a dry film resist of the present invention.

FIG. 2 is a schematic sectional view showing a configuration of a conventional dry film resist.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Transparent base film 2 Release layer 3 Photoresist layer

Claims (6)

(57) [Claims] 1. An olefin which is provided with a photoresist layer on one surface of a transparent base film and has a mold release property with respect to the photoresist layer on another surface of the base film.
A dry film resist comprising a composite film in which a release layer of a resin-based resin is laminated, wherein the composite film is wound into a roll so that the photoresist layer is protected by the release layer. 2. The dry film resist according to claim 1, wherein the transparent base film is a biaxially stretched polyethylene terephthalate film. 3. A dry photoresist release layer of the olefin resin is extrusion lamination or laminated claim 1 wherein a co-extrusion method. 4. The release layer of the olefin resin is a dry photoresist of claim 1 or 3, wherein with the 0.1~10μm of irregularities on the surface thereof. 5. A dry photoresist of claim 1, 3 or 4, wherein the olefin resin is polypropylene or medium density polyethylene. 6. A is not less 50μm or less total thickness of the transparent base film and the release layer, and the thickness of the release layer is dry photoresist of claim 1 Symbol placement is less than 1/2 of the total thickness.