JP6329499B2 - Etching protection resin composition and etching protection sheet - Google Patents

Description

  The present invention relates to a resin composition for etching protection and an etching protective sheet.

  A method of forming a circuit such as a printed wiring board is as follows. First, a resist film is formed on a pre-processed substrate, then the circuit pattern is exposed through a photomask and cured into a circuit pattern, and then a weak alkaline aqueous solution. The uncured portion is developed using an alkaline developer, and a resist pattern is formed on the substrate. Next, the exposed metal layer other than the resist image portion is etched away with an etching solution, and then the resist image is removed using a resist stripping solution that is a strong alkaline aqueous solution.

  Many of the printed wiring boards on which circuits are formed in this way have circuits formed on both sides or only one side of the substrate. However, in the production of a multilayer printed wiring board, a printed wiring board having a solid metal part in which a circuit is formed on one side (A side) of the substrate and a metal layer is left almost entirely on the other side (B side). May be required. In response to this requirement, a resist film is applied to the B surface, and the entire surface is exposed and cured to form a masking material that can withstand etching, and then an etching resist layer is formed on the A surface and then etched. A circuit is formed, and then, in a resist stripping step, a manufacturing method is performed in which the masking material on the B side is stripped together with the A-side etching resist layer.

  For example, when manufacturing a rigid-flex type printed wiring board, a coverlay is produced by screen printing on a flexible circuit board on which a circuit has been formed in advance, and the flexible circuit board and the interlayer adhesive sheet are laminated. A manufacturing method for forming a circuit in a rigid portion has been performed. When a circuit is formed again on the rigid portion, resist film formation, pattern exposure, alkali development, etching, and resist stripping steps are performed, so that the circuit portion on the flexible wiring board on which the circuit has already been formed is protected. A masking tape that is necessary and is not peeled off by the etching solution is applied to the area to be protected.

  In this way, there are many demands for protecting metal solid parts and circuit parts from corrosion caused by etching, in the field of forming circuits by etching metal parts such as printed wiring boards, lead frames, and shadow masks. Masking materials and masking tapes using hardened resist films are used.

  However, in the method using a cured resist film, there is a problem that a pinhole is generated due to partial curing failure at the time of exposure, a trouble of performing entire exposure, and a resist film that is affected by light or heat. There was a problem of handling. Further, in the method using the masking tape, there are problems that the adhesive remains on the substrate after the masking tape is peeled off, and troubles in physically peeling the masking tape.

  For such a problem, (A) a layer (metal layer) dissolved in an etching solution (A) on a layer (uncured resist film, acrylic resin) that is dissolved in the resist removal solution and has adhesiveness ( B) An etching protective sheet is disclosed in which any one of the layers (cured resist film) that dissolves in the resist removing solution and does not dissolve in the alkali developer is disclosed. For the production of a cured resist film, Full exposure is required, and there is also a problem in the handling of uncured resist films (see, for example, Patent Document 1).

JP 2004-60030 A

  The problem of the present invention is that it is possible to protect the metal solid part and the circuit part so as not to be corroded by etching, and it is not necessary to expose the entire surface, and it is not necessary to physically remove the resist by removing the resist. The present invention provides an etching protective sheet that does not take up any damage.

As a result of intensive studies to solve the above problems, it contains at least (A) an alkali-soluble resin containing a benzyl group, and (B) at least one compound selected from the group of the following general formulas (b1) and (b2) and Ri Na to, (a) an alkali-soluble resin of benzyl methacrylate / methacrylic acid weight ratio 85 / 15-90 / 10 in copolymerized was copolymerized resin der Ru etching protective resin composition and the containing benzyl An etching protective sheet having a layer containing a resin composition for etching protection was found.

（式中ｍは、平均付加モル数であり、１〜１０の数である）

(Where m is the average number of moles added and is a number from 1 to 10)

（式中ｎは、平均付加モル数であり、１〜１０の数である）

(Where n is the average number of moles added and is a number from 1 to 10)

  The resin composition for etching protection and the etching protective sheet of the present invention are metal solid parts that need to be protected from corrosion due to etching in the field of forming circuits by etching metal parts such as printed wiring boards, lead frames, and shadow masks. And a circuit part (hereinafter referred to as “protection part”). And while the steps of resist film formation, pattern exposure, alkali development, etching, etc. are performed, the protective part is not peeled off, the etchant does not penetrate, and the metal part of the protective part can be protected from the etchant. it can. Moreover, since it peels from a protection part with a resist peeling liquid in a resist peeling process, there exists an advantage that an adhesive substance does not remain like a masking tape. Furthermore, it is less affected by light and heat unlike a resist film, and is excellent in handling. In addition, since there is no need for a curing process such as full exposure, there is an advantage that it does not take time and effort.

  Hereinafter, the resin composition for etching protection and the etching protective sheet of the present invention will be described in detail.

  The resin composition for etching protection of the present invention contains at least (A) an alkali-soluble resin containing a benzyl group, and (B) at least one compound selected from the group of the general formulas (b1) and (b2). Become.

  (A) Examples of the alkali-soluble resin containing a benzyl group include acrylic resins containing a benzyl group and a carboxyl group. That is, an acrylic polymer obtained by copolymerizing at least an ethylenically unsaturated carboxylic acid and a (meth) acrylate having a benzyl group such as benzyl (meth) acrylate. Other monomers having a copolymerizable ethylenically unsaturated group may be copolymerized.

  (A) The content of the (meth) acrylate having a benzyl group with respect to the alkali-soluble resin containing a benzyl group is preferably 50 to 95% by mass, more preferably 80 to 95% by mass, and still more preferably. Is 85-90 mass%. If the content is less than 50% by mass, the alkaline developer may easily swell. Moreover, when this content exceeds 95 mass%, it may become difficult to remove with a resist stripping solution.

  Monocarboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid are preferably used as the ethylenically unsaturated carboxylic acid, and dicarboxylic acids such as maleic acid, fumaric acid, and itaconic acid, and anhydrides and half esters thereof. It can also be used. Among these, acrylic acid and methacrylic acid are particularly preferable.

  (A) The content of the ethylenically unsaturated carboxylic acid with respect to the alkali-soluble resin containing a benzyl group is preferably 5 to 35% by mass, more preferably 7 to 20% by mass, and still more preferably 10%. ˜15 mass%. If the content is less than 5% by mass, it may be difficult to remove with a resist stripping solution. Moreover, when this content exceeds 35 mass%, it may become easy to swell to an alkali developing solution.

  Examples of the monomer having a copolymerizable ethylenically unsaturated group include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl ( (Meth) acrylate, isobutyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, Glycidyl (meth) acrylate, lauryl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, 2- (dimethylamino) ethyl (meth) acrylate, 2- (diethylamino) ethyl (meth) acrylate, 2,2,2 Trifluoroethyl (meth) acrylate, 2,2,3,3-tetrafluoropropyl (meth) acrylate, styrene, α-methylstyrene, p-methylstyrene, p-ethylstyrene, p-methoxystyrene, p-ethoxystyrene , P-chlorostyrene, p-bromostyrene, (meth) acrylonitrile, (meth) acrylamide, diacetone acrylamide, vinyl toluene, vinyl acetate, vinyl n-butyl ether and the like.

  (A) The acid value of the alkali-soluble resin is preferably 30 to 150 mgKOH / g, and more preferably 50 to 120 mgKOH / g. When the acid value is less than 30 mgKOH / g, the stripping time in the resist stripping process may be long. On the other hand, when the acid value exceeds 150 mgKOH / g, the dimension of the resin composition for etching protection changes in the alkali development step, and the metal part of the protective part may be etched.

  The mass average molecular weight of the (A) alkali-soluble resin is preferably 10,000 to 200,000, and more preferably 50,000 to 150,000. If the mass average molecular weight is less than 10,000, it may be difficult to keep the etching protection resin composition in a film state, and the metal part of the protective part may be etched. On the other hand, when the mass average molecular weight exceeds 200,000, the solubility in the resist stripping solution may deteriorate.

  The resin composition for etching protection of the present invention contains at least one compound selected from the group consisting of general formulas (b1) and (b2). m and n are average addition mole numbers, are 1-10, More preferably, it is 1-6. At least one compound selected from the group of the general formulas (b1) and (b2) may be contained alone or in combination of two or more.

  You may make the resin composition for etching protection of this invention contain components other than the said component (A) and (B) as needed. Such components include solvents, plasticizers, colorants (dyes, pigments), fillers, antifoaming agents, flame retardants, adhesion-imparting agents, leveling agents, release accelerators, antioxidants, perfumes, and thermosetting. Agent, photocuring agent, water repellent and oil repellent, and the like, each of which can be contained in an amount of about 0.01 to 20% by mass. These components can be used individually by 1 type or in combination of 2 or more types.

  In the resin composition for etching protection of the present invention, the amount of component (A) is preferably 60 to 80% by mass based on the total amount of components (A) and (B). When the blending amount of the component (A) is less than 60% by mass, the alkali developer resistance may be deteriorated. If the amount of component (A) exceeds 80% by mass, it may be difficult to remove with a resist stripper.

  The resin composition for etching protection of the present invention can be used in the field of forming circuits by etching metal parts such as printed wiring boards, lead frames and shadow masks. For example, in a method of forming a circuit such as a printed wiring board, first, a resist film is formed on a pretreated substrate, then the circuit pattern is exposed through a photomask and cured into a circuit pattern, and then an alkali is formed. The uncured portion is developed using a developer to form a resist pattern on the substrate. Next, the exposed metal layer other than the resist image portion is removed by etching with an etching solution, and then the resist image is removed using a resist stripping solution.

  Examples of the alkali developer include a 0.1 to 3% by mass aqueous solution of an inorganic basic compound such as an alkali metal carbonate, phosphoric acid or ammonium carbonate. Developer can be used. In alkali development, it is preferable to adjust the concentration, temperature, spray pressure, etc. in order to control the solubility in the cured resist film. The higher the temperature of the alkali developer, the faster the uncured resist film dissolves, but about 30 ° C. is preferred. The alkaline developer generally preferably used contains sodium carbonate, and its preferred concentration is 0.2 to 1.5% by mass. Examples of the apparatus used for alkali development include a dip treatment apparatus, an ultrasonic apparatus, a shower spray apparatus, and the like.

  As the etchant, an acidic etchant that can etch the metal part can be used. For example, an aqueous solution of sulfuric acid-hydrogen peroxide, cupric chloride, persulfate, ferric chloride, nitric acid, sulfuric acid, hydrochloric acid or the like can be used although it varies depending on the type of metal to be etched. Examples of the apparatus and method used for etching include apparatuses and methods such as horizontal spray etching and immersion etching.

  As the resist stripping solution, an aqueous solution of a stronger alkali than the alkali developer is usefully used. For example, an aqueous solution of an inorganic basic compound such as an alkali metal hydroxide, an organic basic compound such as ethanolamine, ethylenediamine, propanediamine, triethylenetetramine, morpholine, and tetramethylammonium hydroxide can be used. The resist film developer used in the above can be used. In the resist stripping, it is preferable to adjust the concentration, temperature, spray pressure and the like in order to control the stripping property with respect to the cured resist film or the resin composition for etching protection of the present invention. The higher the temperature of the resist stripping solution, the faster the stripping rate, and the preferred temperature is 40 ° C. or higher. About a density | concentration, when sodium hydroxide is used, 1-4 mass% is preferable. Examples of the apparatus used for resist stripping include a dip processing apparatus, an ultrasonic apparatus, and a shower spray apparatus.

  The resin composition for etching protection of the present invention can be used as an etching protective sheet having a film configuration in which a layer comprising the resin composition for etching protection is laminated on a support such as polyethylene terephthalate. In that case, the layer surface containing the resin composition for etching protection is used by thermocompression bonding to the protective part. Alternatively, the etching protection resin composition may be directly applied to the protective portion to form a layer containing the etching protection resin composition.

  The thickness of the layer containing the etching protecting resin composition is preferably 10 to 50 μm. If the thickness exceeds 50 μm, the peeling time may be too long. On the other hand, when the thickness is less than 10 μm, the resistance to alkali developer may be deteriorated or the protective part may be corroded by etching.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in more detail, this invention is not limited to this Example.

(Examples 1-6, Comparative Examples 1 and 2)
Each component was mixed with the compounding quantity shown in Table 1, and the coating liquid for resin compositions for etching protection was obtained. In addition, the unit of each component compounding amount in Table 1 is “part by mass”. The obtained coating solution was coated on a polyethylene terephthalate (PET) film (trade name: R310, 25 μm thickness, manufactured by Mitsubishi Plastics) using a wire bar, and dried at 80 ° C. for 8 minutes. An etching protective sheet formed by laminating a layer (dry film thickness: 30 μm) containing the resin composition for etching protection of Examples 1 to 6 and Comparative Examples 1 and 2 on one side of the PET film Obtained.

  In Table 1, each component is as follows.

(A) Alkali-soluble resin containing benzyl group (A-1) Copolymerized resin (mass average molecular weight 100000) obtained by copolymerizing benzyl methacrylate / methacrylic acid at a mass ratio of 85/15

  (A-2) A copolymer resin obtained by copolymerizing benzyl methacrylate / methacrylic acid at a mass ratio of 90/10 (mass average molecular weight 100,000)

(B) At least one compound selected from the group consisting of general formulas (b1) and (b2) (B-1) diethylene glycol monophenyl ether (B-2) a compound of m = 5.5 in general formula (b1) ( B-3) Diethylene glycol monobenzyl ether

Others (α-3) Copolymerized resin (mass average molecular weight 100,000) obtained by copolymerizing methyl methacrylate / n-butyl acrylate / methacrylic acid at a mass ratio of 60/15/25

  (Β-4) Polyethylene glycol (4 ethoxy groups)

(Examples 1-6, Comparative Examples 1-2)
The etching protective sheets prepared in Examples 1 to 6 and Comparative Examples 1 and 2 are attached to the entire surface by thermocompression bonding on one side (B surface) of a double-sided copper-clad laminate (copper foil thickness 18 μm, laminate thickness 0.2 mm). I attached. A resist film for circuit formation (manufactured by Hitachi Chemical Co., Ltd., 38 μm thickness) is pasted on the surface opposite to the surface on which the etching protection sheet is pasted (A surface), the circuit pattern is exposed, Spray development was performed with a 1.0% by mass aqueous sodium carbonate solution. At this time, the layer containing the resin composition for etching protection of Comparative Examples 1 and 2 was peeled off by alkali development.

  Next, a cupric chloride etching solution was sprayed to etch the copper foil. Up to this point, the layer containing the resin composition for etching protection of Examples 1 to 6 remained. Thereafter, spraying was performed with a 3% by weight aqueous sodium hydroxide solution to remove the cured resist film on the A side, and at the same time, the layer containing the resin composition for etching protection on the B side was removed. In any of Examples 1 to 6, the layer containing the etching protection resin composition was completely removed. The copper foil (metal solid part) protected by the layer comprising the etching protective resin composition on the B surface is not corroded by the etching solution, and the etching protective resin composition remains Not observed.

(Comparative Example 3)
A resist film (manufactured by Hitachi Chemical Co., Ltd., 38 μm thickness) was attached to both sides of a double-sided copper-clad laminate (copper foil thickness 18 μm, substrate thickness 0.2 mm). The circuit pattern was exposed on one side (A side), and the entire surface was exposed on the other side (B side). Spray development was performed with a 1.0 mass% aqueous sodium carbonate solution. Next, a cupric chloride etching solution was sprayed to etch the copper foil. Next, a 3% by mass aqueous sodium hydroxide solution was sprayed to remove the cured resist films on the A and B sides. As a result, several pinholes due to exposure failure due to foreign matters during exposure were confirmed in the copper foil on the B surface, corrosion due to the etching solution was confirmed, and a good solid metal portion could not be obtained.

(Comparative Example 4)
A masking tape that does not dissolve in an alkaline developer was applied to one side (B side) of a double-sided copper-clad laminate (copper foil thickness 18 μm, substrate thickness 0.2 mm). On the opposite side (A side), a resist film for circuit formation (manufactured by Hitachi Chemical Co., Ltd., 38 μm thickness) is attached, the circuit pattern is exposed, and then a 1.0% by mass sodium carbonate aqueous solution Was spray developed. Next, a cupric chloride etching solution was sprayed to etch the copper foil. Thereafter, spraying was performed with a 3% by mass aqueous sodium hydroxide solution to remove the cured resist film on the A side. Subsequently, the masking tape was peeled off. However, a load was applied when the masking tape was peeled off, the copper foil was broken, and the adhesive remained on the copper foil protected with the masking tape.

(Comparative Example 5)
An uncured resist film (manufactured by Hitachi Chemical Co., Ltd., 38 μm thickness) is laminated on a resist film (manufactured by Hitachi Chemical Co., Ltd., 38 μm thickness) which has been cured by irradiating ultraviolet rays. An etching protective sheet consisting of two layers of an uncured resist film was produced. Next, the etching protective sheet was attached to one surface (B surface) of a double-sided copper-clad laminate (copper foil thickness 18 μm, laminate thickness 0.2 mm) by thermocompression bonding. A resist film for circuit formation (manufactured by Hitachi Chemical Co., Ltd., 38 μm thickness) is pasted on the surface opposite to the surface on which the etching protection sheet is pasted (A surface), the circuit pattern is exposed, Spray development was performed with a 1.0% by mass aqueous sodium carbonate solution. Next, a cupric chloride etching solution was sprayed to etch the copper foil. Thereafter, spraying was performed with a 3% by mass aqueous sodium hydroxide solution to remove the cured resist film on the A side, and at the same time, the etching protective sheet on the B side was removed. Preparation of the cured resist film for the etching protection sheet requires whole-surface exposure, and several pinholes due to exposure failure due to foreign matters during exposure were confirmed. In addition, it is necessary to pay attention to light and heat for handling at the time of pasting with a cured and uncured resist film.

  The present invention can be widely used as a resin composition for masking corrosion of a metal part by an etching solution.

Claims (2)

Comprising an alkali-soluble resin, and (B) at least one Ri name containing compound, (A) a benzyl group selected from the group of the following general formula and (b1) (b2) contains at least (A) a benzyl group alkali-soluble resin is etched protective resin composition Ru copolymer resins der obtained by copolymerizing benzyl methacrylate / methacrylic acid in a weight ratio of 85 / 15-90 / 10.

(Where m is the average number of moles added and is a number from 1 to 10)

(Where n is the average number of moles added and is a number from 1 to 10)   The etching protection sheet which has a layer formed by containing the resin composition for etching protection of Claim 1.