JP2007043023A - Resin composition for coverlay and its utilization - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin composition for a coverlay which can be suitably used for the manufacturing of a circuit substrate and is not only excellent in heat resistance, an adhesive property, workability, and bendability but is excellent in characteristics such as resistance for a moisture test by a pressure cooker (PCT resistance) and a dielectric property etc., and to provide its typical utilization technology. <P>SOLUTION: The resin composition for the coverlay contains (A) a polyimide resin component, (B) a amine component, (C) an epoxy resin component, and (D) an imidazole component. Each component of the (A)-(C) is mixed so as to be within a limit of a weight mixing ratio (A)/[(B)+(C)]=0.4-2.0. Whereby, characteristics such as an adhesive property, workability, heat resistance, and bendability are effectively provided for the well-balanced resin composition for the coverlay and a hardened film after hardening. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a resin composition for coverlay and use thereof, and in particular, comprises a polyimide resin component, an amine component, an epoxy resin component, and an imidazole component as essential components, and is a coverlay resin for flexible printed wiring boards. The present invention relates to a resin composition for coverlay that can be suitably used as a composition and typical uses such as a circuit board.

  Flexible printed wiring boards (hereinafter abbreviated as FPC) are mainly manufactured using copper-clad laminates (hereinafter abbreviated as CCL), but the surface (conductor surface) of FPC using such CCL. ), The copper circuit wiring formed in a predetermined pattern is exposed. Since this circuit wiring may be altered as it is, a coverlay film is often laminated on the surface.

As a method for laminating a coverlay film on the surface of the CCL, the following method is generally used.
(1) The cover lay film formed on the release film is processed into a predetermined shape, and is overlapped at a predetermined position of the CCL so that the cover lay film and the CCL are in contact with each other by a hot roll laminating machine or a press machine. Thermocompression bonding. Thereafter, the release film is peeled off.
(2) The cover lay film formed on the release film is overlapped so that the cover lay film and the CCL are in contact with each other and thermocompression-bonded with a hot roll laminating machine or a press machine, and the release film is peeled off. A part of the cover lay film formed on the surface of the CCL is removed (etched) with a laser, plasma, chemical, or the like to form a hole, a window, or the like only at a predetermined position of the cover lay film.

  In any of the above laminating methods, it is necessary to embed a line between circuit wirings with a resin at the time of thermocompression bonding.

  In recent years, circuit patterns have been miniaturized, and a circuit having a narrow L / S (line / space), specifically, for example, a circuit wiring having a line or space of 35 μm or less, preferably 25 μm or less. There is a need for a coverlay film that can be sufficiently filled with a gap, that is, having a sufficiently low melt viscosity during processing.

  Further, the coverlay film is also required to be able to withstand the use of lead-free solder, that is, excellent solder heat resistance, due to environmental pollution problems.

  Furthermore, the coverlay film is also required to have excellent adhesiveness with a wiring board and excellent flexibility when used for a flexible printed wiring board.

  Accordingly, the coverlay film is required to have sufficient space between the circuit lines and to have solder heat resistance and bending resistance.

  Conventionally, as a resin composition for coverlays, an epoxy resin type or an acrylic urethane resin type is mainly used. Epoxy resin-based and acrylic urethane resin-based resin compositions for coverlays are excellent in adhesiveness and workability at low temperatures.

Patent Document 1 discloses a technique using a coverlay resin composition obtained by mixing a specific polyimide resin, an epoxy resin, and an epoxy resin curing accelerator. The resin composition for coverlay obtained by this technique is excellent in heat resistance, adhesiveness, and bending resistance, and can be processed at a low temperature.
JP 2000-226666 A (publication date: August 15, 2000)

  However, the conventional epoxy-based or acrylic urethane-based coverlay resin composition has a problem that swelling or peeling occurs in the solder reflow process.

  The resin composition for coverlay disclosed in Patent Document 1 is a mixture of a polyimide resin and an epoxy compound, and can be bonded at a relatively low temperature. Although it is excellent in flexibility (flexibility), the heat resistance expressed by interline embedding (resin fluidity), melt viscosity, and thermal expansion coefficient of fine wiring circuits with L / S of 25 μm / 25 μm or less Not listed.

  Therefore, it is expected to develop a coverlay film having both heat resistance such as solder heat resistance and thermal expansion, adhesiveness, and resin embedding between fine wires.

  The present invention has been made to solve the above-mentioned conventional problems, and its purpose can be suitably used as a cover lay film of a flexible printed wiring board, and has excellent heat resistance, adhesiveness, and workability. An object of the present invention is to provide a cover lay film that is excellent and has a balance of properties required for a cover lay film such as resin embedding between fine wirings, solder heat resistance, and flexibility.

As a result of intensive studies in view of the above problems, the present inventors have polyimide resin, diamine, epoxy resin, and imidazole as essential components, and the polyimide resin is mixed with epoxy resin and diamine at a predetermined ratio. By using a cover lay film, it has heat resistance such as solder heat resistance and small thermal expansion, excellent adhesiveness and flexibility, and furthermore, the fluidity of resin necessary for embedding circuits is specific As a result, it was found that the processability was excellent and the present invention was completed. That is, the present invention
1) A coverlay film for laminating on a surface of a circuit board on which a circuit is formed, wherein the coverlay film contains at least one polyimide resin (A) a polyimide resin component and at least one amine (B) amine component, (C) epoxy resin component containing at least one epoxy resin, and (D) imidazole component containing at least one imidazole. And (C) the weight mixing ratio (A) / [(B) + (C)] represented by the weight of the polyimide resin component (A) with respect to the total weight of the epoxy resin component is 0.4 or more and 2.0. A coverlay film comprising a resin composition within the following range.
2) The coverlay film is in a semi-cured state, and the minimum melt viscosity is in the range of 100 poise or more and 80,000 poise or less under the condition that the temperature is in the range of 60 ° C. or higher and 200 ° C. or lower. 1. The coverlay film as described in 1) above.
3) The coverlay film according to 1) or 2), wherein the cured film has a coefficient of thermal expansion at 20 ° C. to 100 ° C. of 80 ppm or less.
4) The coverlay film according to any one of 1) to 3), wherein the flexibility measured by an MIT fatigue resistance tester is 10 times or more.
5) The molar mixing ratio (B) / (C) represented by the number of moles of active hydrogen contained in the amine component (B) with respect to the number of moles of epoxy groups in the epoxy resin contained in the epoxy resin component (C). Is in the range of 0.4 to 2.0, the coverlay film according to any one of 1) to 4).
6) The at least one polyimide resin contained in the polyimide resin component (A) is represented by the general formula (1)

（ただし、式中、Ｘ₁は、直結、−Ｏ−、−ＣＯ−、−Ｏ−Ｘ₂−Ｏ−、および、−ＣＯＯ−Ｘ₂−ＯＣＯ−からなる群より選択される２価基であり、Ｘ₂は２価の有機基を表す）で表される構造を有する酸二無水物を少なくとも１種含んでなる（Ａ−１）酸二無水物成分と、少なくとも１種のジアミンを含んでなる（Ａ−２）ジアミン成分と、を反応させて得られるものであることを特徴とする１）ないし５）の何れか１項に記載のカバーレイフィルム。
７）前記回路基板が、ライン／スペースがいずれも、１μｍ〜３５μｍの範囲である回路が形成されていること特徴とする１）〜６）のいずれか一項に記載のカバーレイフィルム。
８）前記回路基板が、ポリイミドフィルム、アラミドフィルム、ポリエチレンテレフタートフィルム、ポリエチレンナフタレートフィルムから選択されるフィルムをベースフィルムとするフレキシブル回路基板であることを特徴とする１）〜７）のいずれか一項に記載のカバーレイフィルム。
９）１）ないし７）の何れか１項に記載のカバーレイフィルムを用いてなる回路基板。
１０）前記回路基板が、ポリイミドフィルム、アラミドフィルム、ポリエチレンテレフタートフィルム、ポリエチレンナフタレートフィルムから選択されるフィルムをベースフィルムとするフレキシブル回路基板であることを特徴とする８）に記載の回路基板。
１１）回路基板の回路が形成された面に塗布・乾燥してカバーレイフィルムにするための樹脂組成物溶液であって、少なくとも１種のポリイミド樹脂を含む（Ａ）ポリイミド樹脂成分と、少なくとも１種のアミン類を含む（Ｂ）アミン成分と、少なくとも１種のエポキシ樹脂を含む（Ｃ）エポキシ樹脂成分と、少なくとも１種のイミダゾールを含む（Ｄ）イミダゾール成分とを含んでおり、上記（Ｂ）アミン成分と（Ｃ）エポキシ樹脂成分との合計重量に対する上記（Ａ）ポリイミド樹脂成分の重量で表される重量混合比（Ａ）／［（Ｂ）＋（Ｃ）］は、０．４以上２．０以下の範囲内となっていることを特徴とする樹脂組成物溶液。

(Wherein, X ₁ is a divalent group selected from the group consisting of direct bond, —O—, —CO—, —O—X ₂ —O—, and —COO—X ₂ —OCO—. And X ₂ represents a divalent organic group) (A-1) comprising at least one acid dianhydride having a structure represented by (A-1) and at least one diamine The coverlay film according to any one of 1) to 5), which is obtained by reacting (A-2) a diamine component comprising:
7) The cover lay film according to any one of 1) to 6), wherein the circuit board is formed with a circuit having a line / space in the range of 1 μm to 35 μm.
8) The circuit board is a flexible circuit board having a base film made of a film selected from a polyimide film, an aramid film, a polyethylene terephthalate film, and a polyethylene naphthalate film. The coverlay film according to one item.
9) A circuit board using the coverlay film according to any one of 1) to 7).
10) The circuit board according to 8), wherein the circuit board is a flexible circuit board having a film selected from a polyimide film, an aramid film, a polyethylene terephthalate film, and a polyethylene naphthalate film as a base film.
11) A resin composition solution for application to a circuit board surface on which a circuit is formed and drying to form a coverlay film, comprising (A) a polyimide resin component containing at least one polyimide resin, and at least one (B) an amine component containing various amines, (C) an epoxy resin component containing at least one epoxy resin, and (D) an imidazole component containing at least one imidazole. The weight mixing ratio (A) / [(B) + (C)] represented by the weight of the (A) polyimide resin component with respect to the total weight of the amine component and (C) epoxy resin component is 0.4 or more. A resin composition solution characterized by being in a range of 2.0 or less.

  As described above, the coverlay film or the resin composition solution according to the present invention includes (A) a polyimide resin component, (B) an amine component, (C) an epoxy resin component, and (D) an imidazole component as essential components. The mixing ratio of (B) amine component and (C) epoxy resin component is within a predetermined range with respect to (A) polyimide resin component.

  As a result, it has excellent heat resistance such as solder heat resistance and small thermal expansion, and excellent adhesiveness. Furthermore, the fluidity of the resin necessary for embedding a circuit has been specifically improved, resulting in excellent workability. Coverlay film can be provided. In addition, the cured film obtained by curing the coverlay film is excellent in flex resistance and solder heat resistance by using a polyimide resin, and contains an appropriate amount of epoxy resin. Therefore, the coverlay resin composition having a small thermal expansion coefficient can be provided.

  Therefore, the cover lay film according to the present invention balances various characteristics such as excellent heat resistance (low linear expansion coefficient), adhesion, workability, solder heat resistance, and flexibility as compared with the conventional cover lay film. There is an effect that it can be realized well. Moreover, the effect that it can be used suitably for manufacture of the flexible printed wiring board by which heat resistance and a flexibility are requested | required is also show | played.

  One embodiment of the present invention will be described in detail below, but the present invention is not limited to the following description.

  In the present embodiment, the present invention will be described in detail in the order of the outline of the coverlay film according to the present invention, each component of the coverlay film, and the production of the coverlay film.

(I) Overview of Coverlay Film According to the Present Invention <Composition of coverlay film 1: Mixing ratio of components (A) to (C)>
The thermosetting resin composition according to the present invention contains at least four components (A) a polyimide resin component, (B) an amine component, (C) an epoxy resin component, and (D) an imidazole component, which will be described later. (E) Other components may be included. Each component (essential component) of the above (A) to (D) only needs to contain at least one substance classified into each component. Among these components, in the present invention, by defining the mixing ratio of at least the components (A) to (C) within a specific range, the coverlay film obtained and the coverlay film after curing are obtained. Various characteristics such as heat resistance, adhesiveness, workability, and flexibility can be provided in a sufficient and balanced manner. As a result, the properties as a coverlay film can be improved, and the properties as an insulating layer after curing can be improved.

  The mixing ratio of the components (A) to (C) is defined by a weight ratio. In the thermosetting resin composition according to the present invention, when the weights of the components (A) to (C) mixed in the thermosetting resin composition are represented by symbols (A) to (C), The weight mixing ratio (A) / [(B) + (C)] of the (A) polyimide resin component to the total weight (B) + (C) of the (B) amine component and (C) epoxy resin component is It is within a predetermined range.

  Specifically, the lower limit of the weight mixing ratio (A) / [(B) + (C)] may be 0.4 or more, and is preferably 0.5 or more. On the other hand, the upper limit of the weight mixing ratio (A) / [(B) + (C)] may be 2.0 or less, and is preferably 1.5 or less. Therefore, the preferable range of the weight mixing ratio is in the range of 0.4 to 2.0.

  The weight mixing ratio is less than 0.4, that is, the content of (B) amine component and (C) epoxy resin component ((B) + (C)) contained in the coverlay film is (A ) If the content is relatively larger than the content of the polyimide resin component, the flexibility and solder heat resistance cannot be made sufficient.

  On the other hand, the weight mixing ratio exceeds 2.0, that is, the content of the (A) polyimide resin component contained in the coverlay film is (B) an amine component and (C) an epoxy resin component. When the content is relatively larger than the content ((B) + (C)), in the coverlay film before curing, the adhesiveness between the coverlay film and the conductor or circuit board, the coverlay film and the conductor or circuit The workability at the time of bonding with the substrate is impaired, and in particular, the circuit embedding property is greatly impaired due to a decrease in resin fluidity.

<Composition 2: Coverlay film: Mixing ratio of components (B) and (C)>
In the coverlay film according to the present invention, it is more preferable to define the mixing ratio of the components (B) and (C). The mixing ratio of these two components is defined by the molar ratio. The number of moles of epoxy groups of the epoxy resin contained in the (C) epoxy resin component is represented by the symbol (C) as in the case of the weight, and the number of moles of active hydrogen contained in the (B) amine component is represented by the symbol. When represented by (B), the molar mixing ratio (B) / (C) of these two components is preferably within a predetermined range.

  Specifically, the lower limit value of the molar mixing ratio (B) / (C) is preferably 0.4 or more, and more preferably 0.7 or more. On the other hand, the upper limit of the molar mixing ratio (B) / (C) is preferably 2.0 or less, and more preferably 1.1 or less. Therefore, the preferable range of the molar mixing ratio is in the range of 0.4 to 2.0.

  When the molar mixing ratio is less than 0.4 or exceeds 2.0, the heat resistance such as solder heat resistance and thermal expansion of the cover lay film after curing is adversely affected.

  In addition, each mole number of an epoxy group and active hydrogen is computed from the molecular weight of an epoxy value and diamine. The active hydrogen in the present invention refers to a hydrogen atom directly bonded to a nitrogen atom of an amino group, and generally there are two active hydrogens for one amino group.

  In addition, about the mixing ratio of (D) imidazole component which is another essential component in the coverlay film concerning this invention, (II-4) (D) in each component of the coverlay film concerning this invention (II) Although described in detail in the section of the imidazole component, the mixing ratio of the (D) imidazole component is 0.01 parts by weight or more and 10.0 parts by weight or less with respect to 100 parts by weight of the total amount of the components (A) to (C). It is preferable to be within the range.

  In the present invention, as described above, at least (A) to (A) polyimide resin component, (B) amine component, (C) epoxy resin component, and (D) imidazole component that are essential components of the coverlay film. The mixing ratio (blending ratio) of component (C) is defined by weight ratio, preferably the mixing ratio of components (B) and (C) is defined by molar ratio, more preferably the mixing ratio of component (D) is by weight. It is specified as a ratio. As a result, the cover lay film and the cured film are not only excellent in heat resistance, adhesiveness, workability, and flexibility, but also moisture resistance test resistance (PCT resistance) and insulation by pressure cooker. Various characteristics such as properties can also be made excellent, and the balance of these characteristics can be made good.

<Characteristics of coverlay film>
The coverlay film according to the present invention includes the components (A) to (D) as essential components,
The mixing ratio of the components (A) to (C) is defined by weight ratio or molar ratio. Although the specific characteristics in this resin composition for coverlay are not specifically limited, the minimum value (minimum melt viscosity) of the melt viscosity under specific conditions is specified among the characteristics before curing (semi-cured state). Thereby, resin fluidity | liquidity can be made more preferable. Specifically, it is preferable that the minimum melt viscosity is in the range of 100 poise or more and 80000 poise or less in a semi-cured state and a temperature in the range of 60 ° C. or more and 200 ° C. or less.

  When the minimum melt viscosity under the above conditions exceeds 80000 poise, the resin fluidity becomes insufficient and the circuit embedding property is lowered. On the other hand, if it is less than 100 poise, a large amount of the heat-resistant resin composition protrudes to the outside of the substrate during processing, and the amount of resin remaining on the substrate decreases. As a result, the circuit cannot be embedded.

  In the present invention, by defining the mixing ratio of the above components, adhesion between the coverlay film and an adherend such as a conductor or a circuit board, and workability when the coverlay film is bonded to a conductor or a circuit board In addition to being excellent in various properties such as heat resistance such as low handling property, solder heat resistance and thermal expansion coefficient and high thermal decomposition temperature, it can also be excellent in flexibility. Moreover, in the obtained cover lay film and the cured film, these various characteristics can be realized in a balanced manner. Therefore, the cover lay film of the present invention can be suitably used for the production of a flexible printed wiring board, and the present invention. Various characteristics can be imparted to a circuit board obtained using the coverlay film.

(II) Components of Coverlay Film According to the Present Invention Next, the components (A) to (D) used in the present invention, and (E) other components will be described more specifically.

(II-1) (A) Polyimide resin component The (A) polyimide resin component used by this invention should just contain at least 1 type of polyimide resin. The cover lay film according to the present invention contains this (A) polyimide resin component, so that sufficient heat resistance is imparted, and the cured film has flexibility, excellent mechanical properties, and chemical resistance. Sex can be imparted.

  The polyimide resin used as the (A) polyimide resin component in the present invention is not particularly limited, but is preferably a soluble polyimide resin that dissolves in an organic solvent. Here, the soluble polyimide resin refers to a polyimide resin that dissolves in an organic solvent in an amount of 1% by weight or more in a temperature range of 15 ° C to 100 ° C. Examples of the organic solvent include ether solvents such as dioxane, dioxolane and tetrahydrofuran; acetamide solvents such as N, N-dimethylformamide and N, N-diethylacetamide; formamide solvents such as N, N-diethylformamide and the like. Examples of the solvent include at least one solvent selected from N, N-dimethylacetamide; pyrrolidone solvents such as N-methyl-2-pyrrolidone and N-vinyl-2-pyrrolidone. These solvent may use only 1 type and may use it combining 2 or more types by arbitrary ratios.

  If the said soluble polyimide resin is used, when the coverlay film concerning this invention is thermosetted, the process for high temperature and long time is not required. Therefore, the epoxy resin component (C) described later can be efficiently cured. That is, in the present invention, it is preferable to use a soluble polyimide resin as one of the (A) polyimide resin components from the viewpoint of improving processability and handleability.

  The said polyimide resin can be manufactured by a conventionally well-known method. Specifically, for example, it can be obtained by chemically or thermally imidizing polyamic acid (polyamic acid) which is a precursor material of polyimide resin. Hereinafter, a method for producing a polyimide resin from a polyamic acid by imidization will be described in detail.

<Production (synthesis) method of polyamic acid>
The polyamic acid contains, as monomer raw materials, an (A-1) acid dianhydride component containing at least one acid dianhydride and a (A-2) diamine component containing at least one diamine in an organic solvent. It can synthesize | combine by making it react with. At this time, the total amount of the (A-1) acid dianhydride component and the total amount of the (A-2) diamine component are mixed so as to be substantially equimolar. Accordingly, when two or more compounds are used as (A-1) acid dianhydride component and (A-2) diamine component, respectively, the molar ratio of the total amount of plural diamines and the molar ratio of the total amount of plural acid dianhydrides Are adjusted so as to be substantially equimolar, a polyamic acid copolymer can be obtained.

  In addition, the (A-2) diamine component said here is a monomer raw material for synthesize | combining the polyamic acid which is a precursor of a polyimide resin, Comprising: It is an essential component of the thermosetting resin composition concerning this invention ( B) Needless to say, it is a component different from the amine component. For the convenience of explanation, in order to clearly distinguish from the component (B) of the thermosetting resin composition such as amine component, the monomer raw material component of the polyamic acid is referred to as “(A-1) monomeric acid dianhydride component”, respectively. And “(A-2) monomer diamine component”.

  The method of reacting the (A-1) monomeric acid dianhydride component and the (A-2) monomer diamine component is not particularly limited, but a typical method is (A-2) monomer diamine. A solution obtained by dissolving a polyamic acid in an organic solvent by dissolving the components in an organic solvent and then adding and mixing the monomer acid dianhydride component (hereinafter referred to as a polyamic acid solution). The method of obtaining is mentioned. Here, “dissolved” means a state in which the solvent completely dissolves the solute and a state in which the solute is uniformly dispersed or diffused in the solvent and is substantially in a dissolved state. Shall be included.

  The addition of the (A-1) monomeric dianhydride component and the (A-2) monomer diamine component is not limited to the above order, and those skilled in the art can appropriately change the addition method. Can be modified / modified. For example, (A-1) a monomer acid dianhydride component may be first dissolved or dispersed in an organic solvent, and then (A-2) a monomer diamine component may be added. Alternatively, first, an appropriate amount of the (A-2) monomer diamine component is added to the organic solvent, and then the amount of the (A-1) monomer that is excessive relative to the total amount of the added (A-2) monomer diamine component. It may be a method of adding an acid dianhydride component and then adding (A-1) a monomer diamine component in an amount corresponding to the excess amount of (A-1) monomeric acid dianhydride.

  The reaction conditions (polyamide acid synthesis conditions) of the above (A-1) monomeric acid dianhydride component and (A-2) monomeric diamine component are not particularly limited, and the acid dianhydride that is a monomer raw material and Any conditions may be used as long as the diamine can be polymerized. However, among the reaction conditions, the reaction temperature is preferably 80 ° C. or lower, and more preferably in the range of 0 to 50 ° C. Moreover, what is necessary is just to set reaction time arbitrarily in the range of 30 minutes-50 hours. If the reaction temperature and reaction time are within these ranges, the polyamic acid can be efficiently synthesized.

  The organic solvent used for the synthesis of the polyamic acid is not particularly limited as long as it is an organic polar solvent. However, it is preferable to select an organic solvent that is a good solvent for the polyamic acid and has a boiling point as low as possible. When such an organic solvent is used, (1) the viscosity of the reaction solution increases when the monomer raw material components (A-1) and (A-2) are subjected to a polymerization reaction (during synthesis of polyamic acid). This is preferable in terms of the production process from the viewpoint of making it easy to stir and suppressing (2) easy drying of the resulting polyimide resin.

  Specific examples of the organic solvent include sulfoxide solvents such as dimethyl sulfoxide and diethyl sulfoxide; formamide solvents such as N, N-dimethylformamide and N, N-diethylformamide; N, N-dimethylacetamide and N, Acetamide solvents such as N-diethylacetamide; Pyrrolidone solvents such as N-methyl-2-pyrrolidone and N-vinyl-2-pyrrolidone; Phenol, o-cresol, m-cresol, p-cresol, xylenol, halogenated phenol And phenol solvents such as catechol; hexamethylphosphoramide, γ-butyrolactone, and the like. These solvent may use only 1 type and may use it combining 2 or more types by arbitrary ratios. Furthermore, you may use it combining aromatic hydrocarbons, such as xylene or toluene, with respect to the said organic solvent as needed.

<(A-1) Monomer acid dianhydride component>
The (A-1) monomeric acid dianhydride component as the monomer raw material used for the synthesis of the polyamic acid is not particularly limited, and in particular, the polyimide resin finally obtained has solubility in various organic solvents. A known acid dianhydride can be used if various properties such as heat resistance and compatibility with the other essential components (B) to (D) can be sufficiently realized. Of these, aromatic tetracarboxylic dianhydrides are preferred. In particular, the aromatic tetracarboxylic dianhydride has the following general formula (1)

（ただし、式中、Ｘ₁は、直結、−Ｏ−、−ＣＯ−、−Ｏ−Ｘ₂−Ｏ−、および、−ＣＯＯ−Ｘ₂−ＯＣＯ−からなる群より選択される２価基であり、Ｘ₂は２価の有機基を表す）で表される構造を有する化合物であることが好ましい。このような構造を有する酸二無水物は、１種のみを用いてもよく、２種以上を任意の割合で組み合わせて用いてもよい。

(Wherein, X ₁ is a divalent group selected from the group consisting of direct bond, —O—, —CO—, —O—X ₂ —O—, and —COO—X ₂ —OCO—. And X ₂ represents a divalent organic group) and is preferably a compound having a structure represented by: Only one type of acid dianhydride having such a structure may be used, or two or more types may be used in combination at any ratio.

In the acid dianhydride having the structure represented by the general formula (1) (referred to as “acid dianhydride of the formula (1)” for convenience of explanation), the thermosetting resin composition finally obtained X ₁ in the general formula (1) is —O—X ₂ —O— or —COO—X ₂ —OCO— because the heat resistance of the product and the cured resin can be made excellent. preferable. Here, X ₂ is a group of formulas (1-1) shown below.

から選択される２価の芳香族有機基、または、次に示す一般式（１−２）

Or a divalent aromatic organic group selected from the following general formula (1-2)

（ただし、式中、Ｘ₃は、−ＣpＨ2p−、−Ｃ(＝Ｏ)−、−ＳＯ₂−、−Ｏ−、および、−Ｓ−からなる群より選択される２価基であり、ｐは１以上５以下の整数である）で表される構造を有する２価の芳香族有機基の何れかであることが好ましい。

(Wherein, X ₃ is a divalent group selected from the group consisting of —CH 2 p—, —C (═O) —, —SO ₂ —, —O—, and —S—; Is an integer of 1 or more and 5 or less, and is preferably any one of divalent aromatic organic groups having a structure represented by:

  Among the above aromatic tetracarboxylic dianhydrides, it is particularly preferable to use 4,4 '-(4,4'-isopropylidenediphenoxy) bisphthalic dianhydride represented by the following structural formula.

この４，４’−（４，４’−イソプロピリデンジフェノキシ）ビスフタル酸二無水物は、得られるポリアミド酸やポリイミド樹脂に対して、各種の有機溶媒に対する溶解性、耐熱性、（Ｂ）アミン成分および（Ｃ）エポキシ樹脂成分との相溶性、屈曲性等の諸特性を十分なものにできるとともに、各諸特性のバランスも良好なものとすることができる。
また、（Ａ−１）モノマー酸二無水物成分として用いる化合物としては入手しやすいという利点もある。

This 4,4 '-(4,4'-isopropylidenediphenoxy) bisphthalic dianhydride is soluble in various organic solvents and heat resistant to the polyamic acid and polyimide resin obtained. Various properties such as compatibility with the component and (C) the epoxy resin component, flexibility, and the like can be made satisfactory, and the balance between the properties can be made good.
In addition, (A-1) the compound used as the monomeric acid dianhydride component has an advantage that it is easily available.

  As the (A-1) monomeric acid dianhydride component, a plurality of types of compounds (acid dianhydrides) can be used. Therefore, in the present invention, as the at least one acid dianhydride, the above general formula (1 An acid dianhydride having a structure represented by) may be used. That is, as the (A-1) monomeric acid dianhydride component, it is sufficient that at least one acid dianhydride of the above-described formula (1) is contained, and two or more kinds are in any proportion as necessary. In addition, an acid dianhydride other than the acid dianhydride of the above formula (1) (hereinafter, other acid dianhydrides) may be included.

  The content of the acid dianhydride of the above formula (1) in the monomer acid dianhydride component (A-1), that is, the ratio of the acid dianhydride of the formula (1) in all the acid dianhydrides is: It is preferable that it is 50 mol% or more when all the acid dianhydride components are 100 mol%. If the content of the acid dianhydride of the formula (1) is 50 mol% or more, the resulting polyamic acid and polyimide resin have solubility in various organic solvents, (B) amine component and (C) epoxy resin component And various properties such as compatibility and flexibility.

  Among the above-mentioned (A-1) monomeric acid dianhydride components, other acid dianhydrides are not particularly limited, but are aromatic having a structure other than the structure represented by the general formula (1). Tetracarboxylic dianhydride can be preferably used. Specifically, for example, pyromellitic dianhydride [1,2,4,5-benzenetetracarboxylic dianhydride], 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride, 3 , 3 ′, 4,4′-diphenylsulfonetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 3,3 ′, 4,4′-dimethyldiphenylsilanetetracarboxylic dianhydride, 1,2,3,4-furantetracarboxylic dianhydride, 4,4′-bis (3,4-dicarboxyphenoxy) ) Diphenylpropanoic dianhydride, 4,4′-hexafluoroisopropylidene diphthalic anhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 2,3,3 ′, 4 ′ -Biphenylte Rakarubon dianhydride, 4,4'-oxydiphthalic anhydride, mention may be made of p- phenylene phthalic anhydrides. These other acid dianhydrides may be used alone or in combination of two or more at any ratio.

<(A-2) Monomer diamine component>
The monomer diamine component (A-2) as a monomer raw material used for synthesizing the polyamic acid is not particularly limited, and in particular, the polyimide resin finally obtained has solubility and heat resistance in various organic solvents. If various properties such as solder heat resistance, PCT resistance, low water absorption, and thermoplasticity can be sufficiently realized, a known diamine can be used. Of these, aromatic diamines are preferred. In particular, the aromatic diamine includes phenylenediamines such as 1,3-phenylenediamine and 1,2-phenylenediamine, and the following general formula (2):

（ただし、式中、Ｙ₁は、それぞれ独立して、−Ｃ(＝Ｏ)−、−ＳＯ₂−、−Ｏ−，−Ｓ−、−(ＣＨ₂)ｍ−、−ＮＨＣＯ−、−Ｃ(ＣＨ₃)₂−，−Ｃ(ＣＦ₃)₂−，および，−Ｃ(＝Ｏ)Ｏ−からなる群より選択される２価基、または、直接結合を表し、Ｒは、それぞれ独立して、水素原子、ハロゲン原子、または、炭素数１〜４のアルキル基を表し、ｍ，ｎは、それぞれ独立して１以上５以下の整数である）で表される構造を有する化合物であることが好ましく、一般式（２）にて表される構造を有する化合物がより好ましい。なお、ここでいう直接結合とは、２つのベンゼン環のそれぞれに含まれる炭素が直接結合することによって、２つのベンゼン環が結合していることを指す。

(However, in the formula, each Y ₁ independently represents —C (═O) —, —SO ₂ —, —O—, —S—, — (CH ₂ ) m—, —NHCO—, —C It represents a divalent group selected from the group consisting of (CH ₃ ) ₂ —, —C (CF ₃ ) ₂ —, and —C (═O) O—, or a direct bond, and each R is independently And a hydrogen atom, a halogen atom, or an alkyl group having 1 to 4 carbon atoms, and m and n are each independently an integer of 1 to 5). Is preferable, and a compound having a structure represented by the general formula (2) is more preferable. Note that the direct bond referred to here means that two benzene rings are bonded to each other by directly bonding carbon contained in each of the two benzene rings.

  Specific examples of the diamine having the structure represented by the general formula (2) (referred to as “diamine of formula (2)” for convenience of description) include, for example, bis [4- (3-aminophenoxy). ) Phenyl] methane, bis [4- (4-aminophenoxy) phenyl] methane, 1,1-bis [4- (3-aminophenoxy) phenyl] ethane, 1,1-bis [4- (4-amino) Phenoxy) phenyl] ethane, 1,2-bis [4- (3-aminophenoxy) phenyl] ethane, 1,2-bis [4- (4-aminophenoxy) phenyl] ethane, 2,2-bis [4- Bis [((3-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [4- (3-aminophenoxy) phenyl] butane, etc. A Nophenoxy) phenyl] alkanes; 2,2-bis [3- (3-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 2,2-bis [4- ( Bis [(aminophenoxy) phenyl] fluoroalkanes such as 4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane; 1,3-bis (3-aminophenoxy) benzene; Bis (aminophenoxy) benzene compounds such as 1,4-bis (3-aminophenoxy) benzene, 1,4′-bis (4-aminophenoxy) benzene, 4,4′-bis (4-aminophenoxy) biphenyl Bis (aminophenoxy) such as bis [4- (3-aminophenoxy) phenyl] ketone and bis [4- (4-aminophenoxy) phenyl] ketone Bis [(aminophenoxy) phenyl] sulfide compounds such as bis [4- (3-aminophenoxy) phenyl] sulfide and bis [4- (4-aminophenoxy) phenyl] sulfide; bis [4 -(3-Aminophenoxy) phenyl] sulfone, bis [(aminophenoxy) phenyl] sulfone compounds such as bis [4- (4-aminophenoxy) phenyl] sulfone; bis [4- (3-aminophenoxy) phenyl] Ethers, bis [(aminophenoxy) phenyl] ether compounds such as bis [4- (4-aminophenoxy) phenyl] ether; 1,4-bis [4- (3-aminophenoxy) benzoyl] benzene, 1, Bis [(aminophene) such as 3-bis [4- (3-aminophenoxy) benzoyl] benzene Noxy) benzoyl] benzene compounds; bis [4,4′-bis [3- (4-aminophenoxy) benzoyl] diphenyl ether, 4,4′-bis [3- (3-aminophenoxy) benzoyl] diphenyl ether, and the like (Aminophenoxy) benzoyl] diphenyl ether compounds; 4,4′-bis [4- (4-amino-α, α-dimethylbenzyl) phenoxy] benzophenone and other benzophenone compounds; 4,4′-bis [4 (Phenoxy) phenylsulfone compounds such as-(4-amino-α, α-dimethylbenzyl) phenoxy] diphenylsulfone and bis [4- {4- (4-aminophenoxy) phenoxy} phenyl] sulfone; 1,4 -Bis [4- (4-aminophenoxy) -α, α-dimethylbenzyl] benzene, 1, - bis [4- (4-aminophenoxy)-.alpha., alpha-dimethylbenzyl] bis benzene [(aminophenoxy) dimethylbenzene] benzene-based compounds; and the like. These diamines of the formula (2) may be used alone or in combination of two or more at any ratio.

  Among the diamines of the above formula (2), the following general formula (2-1)

（ただし、式中、Ｙ₁は、それぞれ独立して、−Ｃ(＝Ｏ)−、−ＳＯ₂−、−Ｏ−，−Ｓ−、−(ＣＨ₂)ｍ−、−ＮＨＣＯ−、−Ｃ(ＣＨ₃)₂−，−Ｃ(ＣＦ₃)₂−，および，−Ｃ(＝Ｏ)Ｏ−からなる群より選択される２価基、または、直接結合を表し、Ｒは、それぞれ独立して、水素原子、ハロゲン原子、または、炭素数１〜４のアルキル基を表し、ｍ，ｎは、それぞれ独立して１以上５以下の整数である）で表される構造を有するジアミン、すなわちメタ位にアミノ基を有するジアミンをより好ましく用いることができる。式（２）のジアミンがメタ位にアミノ基を有していれば、パラ位にアミノ基を有するジアミンを用いた場合よりも、得られるポリイミド樹脂において各種の有機溶媒に対する溶解性に優れたものとすることができる。

(However, in the formula, each Y ₁ independently represents —C (═O) —, —SO ₂ —, —O—, —S—, — (CH ₂ ) m—, —NHCO—, —C It represents a divalent group selected from the group consisting of (CH ₃ ) ₂ —, —C (CF ₃ ) ₂ —, and —C (═O) O—, or a direct bond, and each R is independently A hydrogen atom, a halogen atom, or an alkyl group having 1 to 4 carbon atoms, and m and n are each independently an integer of 1 or more and 5 or less. A diamine having an amino group at the position can be more preferably used. If the diamine of formula (2) has an amino group at the meta position, the resulting polyimide resin has better solubility in various organic solvents than when a diamine having an amino group at the para position is used. It can be.

  Specific examples of the diamine having the structure represented by the general formula (2-1) (referred to as “meta-position diamine” for the sake of convenience) include, for example, examples of the diamine of the formula (2) described above. 1,1-bis [4- (3-aminophenoxy) phenyl] ethane, 1,2-bis [4- (3-aminophenoxy) phenyl] ethane, 2,2-bis [4 -(3-aminophenoxy) phenyl] propane, 2,2-bis [4- (3) -aminophenoxy] phenyl] butane, 2,2-bis [3- (3-aminophenoxy) phenyl] -1,1 , 1,3,3,3-hexafluoropropane, 1,3-bis (3-aminophenoxy) benzene, 1,4-bis (3-aminophenoxy) benzene, bis [4- (3-aminophenoxy) phenyl ] Bis [4- (3-aminophenoxy) phenyl] sulfide, bis [4- (3-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] ether, 1,4-bis [ 4- (3-aminophenoxy) benzoyl] benzene, 1,3-bis [4- (3-aminophenoxy) benzoyl] benzene, 4,4′-bis [3- (3-aminophenoxy) benzoyl] diphenyl ether, etc. Can be mentioned. These meta diamines may be used alone or in combination of two or more at any ratio.

  Of these, it is particularly preferable to use 1,3-bis (3-aminophenoxy) benzene as the meta-position diamine. The polyimide resin using the 1,3-bis (3-aminophenoxy) benzene can have excellent solubility in various organic solvents. Furthermore, the coverlay film finally obtained and Various properties such as solder heat resistance and flexibility can be further improved with respect to the cured film.

  Further, the diamine contained in the monomer diamine component (A-2) is a diamine having a hydroxyl group (—OH) and / or a carboxyl group (—COOH) (for convenience of explanation, from —OH that is common in structure to “hydroxydiamine”. For example). If this hydroxydiamine is used, a hydroxyl group and / or a carboxyl group can be introduced into the resulting polyimide resin.

  When at least one of a hydroxyl group and a carboxyl group is introduced into the polyimide resin, curing of the epoxy resin component (C) described later can be promoted in the resin composition for coverlay. Therefore, when the cover lay film is cured, it becomes possible to perform the thermosetting of the (C) epoxy resin component at a low temperature or in a short time. Furthermore, since the (C) epoxy resin component reacts with a hydroxyl group or a carboxyl group, the polyimide resins are cross-linked via the epoxy resin. Therefore, the molecular structure of the cured film is strengthened.

  Accordingly, by using the above hydroxydiamine to obtain a polyimide resin into which a hydroxyl group and / or a carboxyl group have been introduced, heat resistance, solder heat resistance, and PCT are obtained for the finally obtained coverlay film and cured film. Various characteristics such as resistance can be further improved.

  The hydroxydiamine is not particularly limited as long as it has at least one of a hydroxyl group and a carboxyl group in its structure. Specifically, for example, diaminophenol compounds such as 2,4-diaminophenol; diaminobiphenyl compounds such as 3,3′-dihydroxy-4,4′-diaminobiphenyl; 3,3′-diamino-4, 4'-dihydroxybiphenyl, 4,4'-diamino-3,3'-dihydroxybiphenyl, 4,4'-diamino-2,2'-dihydroxybiphenyl, 4,4'-diamino-2,2 ', 5 Hydroxybiphenyl compounds such as 5′-tetrahydroxybiphenyl; 3,3′-diamino-4,4′-dihydroxydiphenylmethane, 4,4′-diamino-3,3′-dihydroxydiphenylmethane, 4,4′-diamino -2,2'-dihydroxydiphenylmethane, 2,2-bis [3-amino-4-hydroxyphenyl] propane 2,2-bis [4-amino-3-hydroxyphenyl] propane, 2,2-bis [3-amino-4-hydroxyphenyl] hexafluoropropane, 4,4′-diamino-2,2 ′, 5 Hydroxydiphenylalkanes such as 5′-tetrahydroxydiphenylmethane; 3,3′-diamino-4,4′-dihydroxydiphenyl ether, 4,4′-diamino-3,3′-dihydroxydiphenyl ether, 4,4′-diamino- Hydroxydiphenyl ether compounds such as 2,2′-dihydroxydiphenyl ether and 4,4′-diamino-2,2 ′, 5,5′-tetrahydroxydiphenyl ether; 3,3′-diamino-4,4′-dihydroxydiphenylsulfone 4,4'-diamino-3,3'-dihydroxydiphenylsulfo Diphenylsulfone compounds such as 4,4′-diamino-2,2′-dihydroxydiphenylsulfone, 4,4′-diamino-2,2 ′, 5,5′-tetrahydroxydiphenylsulfone; Bis [(hydroxyphenyl) phenyl] alkanes such as [4- (4-amino-3-hydroxyphenoxy) phenyl] propane; Bis such as 4,4′-bis (4-amino-3-hydroxyphenoxy) biphenyl (Hydroxyphenoxy) biphenyl compounds; bis [(hydroxyphenoxy) phenyl] sulfone compounds such as 2,2-bis [4- (4-amino-3-hydroxyphenoxy) phenyl] sulfone; 3,5-diaminobenzoic acid Diaminobenzoic acids such as acids; 3,3′-diamino-4,4′-dicarboxybiphenyl, 4,4′-dia Carboxy such as Mino-3,3′-dicarboxybiphenyl, 4,4′-diamino-2,2′-dicarboxybiphenyl, 4,4′-diamino-2,2 ′, 5,5′-tetracarboxybiphenyl, etc. Biphenyl compounds; 3,3′-diamino-4,4′-dicarboxydiphenylmethane, 4,4′-diamino-3,3′-dihydroxydiphenylmethane, 4,4′-diamino-2,2′-dihydroxy Diphenylmethane, 2,2-bis [4-amino-3-carboxyphenyl] propane, 2,2-bis [3-amino-4-carboxyphenyl] hexafluoropropane, 4,4′-diamino-2,2 ′, Carboxydiphenylalkanes such as carboxydiphenylmethane such as 5,5′-tetracarboxydiphenylmethane; -4,4'-dicarboxydiphenyl ether, 4,4'-diamino-3,3'-dicarboxydiphenyl ether, 4,4'-diamino-2,2'-dicarboxydiphenyl ether, 4,4'-diamino-2 Carboxydiphenyl ether compounds such as 2,2 ', 5,5'-tetracarboxydiphenyl ether; 3,3'-diamino-4,4'-dicarboxydiphenylsulfone, 4,4'-diamino-3,3'-dicarboxy Diphenyl sulfone compounds such as diphenyl sulfone, 4,4′-diamino-2,2′-dicarboxydiphenyl sulfone, 4,4′-diamino-2,2 ′, 5,5′-tetracarboxydiphenyl sulfone; Bis [((2-bis [4- (4-amino-3-carboxyphenoxy) phenyl] propane) and the like Ruboxyphenyl) phenyl] alkanes; bis (hydroxyphenoxy) biphenyl compounds such as 4,4′-bis (4-amino-3-hydroxyphenoxy) biphenyl; 2,2-bis [4- (4- Bis [(carboxyphenoxy) phenyl] sulfone compounds such as amino-3-carboxyphenoxy) phenyl] sulfone; and the like. These hydroxydiamines may be used alone or in combination of two or more at any ratio.

  Among the above-mentioned compounds, it is particularly preferable to use 3,3′-dihydroxy-4,4′-diaminobiphenyl represented by the following structural formula as the hydroxydiamine.

３，３’−ジヒドロキシ−４，４’−ジアミノビフェニルを（Ａ−２）モノマージアミン成分に含めることで、得られるカバーレイフィルムおよび硬化後フィルムに対して、良好な半田耐熱性やＰＣＴ耐性を与えることが可能となる。

By including 3,3′-dihydroxy-4,4′-diaminobiphenyl in the (A-2) monomer diamine component, the resulting coverlay film and post-cured film have good solder heat resistance and PCT resistance. It becomes possible to give.

  Thus, the monomer diamine component (A-2) contains at least one diamine of the above formula (2) (particularly a meta-position diamine), and further contains at least one hydroxydiamine. It is preferable. Moreover, even when the diamine of Formula (2) is not included, it is preferable that at least one hydroxydiamine is included. That is, in the present invention, it is preferable that the (A-2) monomer diamine component contains at least one diamine and / or hydroxydiamine of the formula (2). Thereby, more excellent solder heat resistance and PCT resistance can be obtained with respect to the coverlay film and the cured film.

  The content of the diamine of the above formula (2) in the monomer diamine component (A-2), that is, the ratio of the diamine of the formula (2) in all diamines is 60 when all diamine components are 100 mol%. It is preferable to be from mol% to 99 mol%. Similarly, the content of the hydroxydiamine in the monomer diamine component (A-2), that is, the ratio of hydroxydiamine in all diamines is 1 mol% or more and 40 mol when all diamine components are 100 mol%. % Or less is preferable. When the content of each diamine deviates from the above range, the obtained coverlay film and the cured film tend to deteriorate the solubility in various organic solvents, solder heat resistance, and PCT resistance.

  In addition, what is necessary is just to combine each said diamine in an arbitrary ratio, respectively, When using together the diamine of the said Formula (2), and hydroxydiamine, what is necessary is just to contain each within the said range.

  Furthermore, the (A-2) monomer diamine component may contain a diamine other than the diamine of formula (2) and hydroxydiamine (referred to as “other diamine” for convenience of description). (A-2) Other diamines contained in the monomer diamine component are not particularly limited, but aromatic diamines can be preferably used.

  Specific examples of the aromatic diamine include m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, m-aminobenzylamine, p-aminobenzylamine, and bis (3-aminophenyl) sulfide. , (3-aminophenyl) (4-aminophenyl) sulfide, bis (4-aminophenyl) sulfide, bis (3-aminophenyl) sulfoxide, (3-aminophenyl) (4-aminophenyl) sulfoxide, bis (3 -Aminophenyl) sulfone, (3-aminophenyl) (4-aminophenyl) sulfone, bis (4-aminophenyl) sulfone, 3,4'-diaminobenzophenone, 4,4'-diaminobenzophenone, 3,3'- Diaminodiphenylmethane, 3,4'-diaminodiphenylmeta 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl ether, 3,3′-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, bis [4- (3-aminophenoxy) phenyl] sulfoxide, bis [4 -(Aminophenoxy) phenyl] sulfoxide and the like can be mentioned.

  These other diamines may be used alone or in combination of two or more in any ratio. Moreover, it is preferable that content of the other diamine in (A-2) monomer diamine component is less than 10 mol% when all the diamine components are 100 mol%.

<Imidization of polyamic acid>
The above (A-1) monomeric acid dianhydride component and (A-2) monomeric diamine component are mixed and stirred in an organic solvent as described in the above section <Production (synthesis) method of polyamic acid>. As a result, a polyamic acid solution is obtained. A soluble polyimide resin can be obtained by imidizing the polyamic acid in the polyamic acid solution. Specific examples of imidization performed at this time include (1) thermal method, (2) chemical method, and (3) vacuum imidization method. By these methods, polyamic acid is dehydrated and cyclized to obtain a polyimide resin.

  The above (1) thermal method is a method in which the polyamic acid solution is heat-treated to perform dehydration and cyclization, and the specific steps thereof are not particularly limited. For example, imidization is performed by heat treatment of the polyamic acid solution. A process such as advancing the reaction and simultaneously evaporating the solvent can be mentioned. By this thermal method, a solid polyimide resin can be obtained. In addition, although the conditions of the said heat processing are not specifically limited, It is preferable to heat at the temperature of 300 degrees C or less for the time of the range of about 5 minutes-20 minutes.

  The above (2) chemical method is a method of dehydrating and ring-closing polyamic acid using a dehydrating agent, and the specific process is not particularly limited. A method of performing a dehydration reaction and evaporation of an organic solvent by adding a dehydrating agent and a catalyst that are more than the stoichiometric amount can be mentioned. By this chemical method, a solid polyimide resin can be obtained.

  Examples of the dehydrating agent include aliphatic acid anhydrides such as acetic anhydride; aromatic acid anhydrides such as benzoic anhydride; carbodiimides such as N, N′-dicyclohexylcarbodiimide and N, N′-diisopropylcarbodiimide. Can do. Examples of the catalyst include aliphatic tertiary amines such as triethylamine; aromatic tertiary amines such as dimethylaniline; heterocyclic groups such as pyridine, α-picoline, β-picoline, γ-picoline, and isoquinoline. Tertiary amines; and the like.

  In addition, it is preferable that the temperature condition at the time of (2) dehydration ring closure by a chemical method is 100 degrees C or less, and it is preferable to carry out reaction time within the range of about 1 minute-50 hours. The evaporation of the organic solvent is preferably performed at a temperature of 200 ° C. or less for a time in the range of about 5 minutes to 120 minutes.

  Further, the (3) vacuum imidization method is a method of imidizing polyamic acid by heat treatment under reduced pressure, and the specific steps thereof are not particularly limited. The heating condition may be in the range of 80 to 400 ° C., but in order to perform imidization and dehydration efficiently, the temperature is more preferably 100 ° C. or more, and further preferably 120 ° C. or more. Here, the maximum temperature in the heat treatment is preferably set to be equal to or lower than the thermal decomposition temperature of the polyimide resin, and is usually set within a temperature range of about 150 ° C. to 350 ° C., which is a complete temperature of imidization. The pressure condition is preferably low pressure. Specifically, it is preferably within a range of 0.001 to 0.9 atmosphere, more preferably within a range of 0.001 to 0.8 atmosphere, and a range of 0.001 to 0.7 atmosphere. More preferably, it is within.

  According to the above (3) vacuum imidization method, water produced by imidization can be positively removed out of the system, so that hydrolysis of polyamic acid can be suppressed. As a result, a high molecular weight polyimide resin can be obtained. Furthermore, if this method is used, one-side ring-opened product or both-side ring-opened products existing as impurities in the acid dianhydride that is a raw material of the polyamic acid can be closed, so that the molecular weight of the polyimide resin is further improved. can do. In the imidation methods (1) to (3) described above, the case of evaporating the solvent has been described as an example. However, the imidization method is not limited to this, and the solvent need not be evaporated. . Specifically, for example, a method of adding a polyimide resin solution obtained by the imidization method of the above (1) and (2) to a poor solvent and precipitating the polyimide resin can be mentioned. In this method, the unreacted monomer (acid dianhydride / diamine) contained in the polyimide resin solution is removed for purification. If this is dried, a higher quality solid polyimide resin can be obtained.

  The poor solvent used in this method is not particularly limited as long as it is well mixed with the solvent of the polyimide resin solution, but the polyimide resin is a solvent that is difficult to dissolve. Specific examples include acetone, methanol, ethanol, isopropanol, benzene, methyl cellosolve (registered trademark), and methyl ethyl ketone. These poor solvents may use only 1 type and may use it combining 2 or more types by arbitrary ratios.

(II-2) (B) Amine Component The (B) amine component used in the present invention may contain at least one amine. The cover lay film according to the present invention can impart good resin fluidity to the cover lay film by containing this (B) amine component, and has good heat resistance to the cured film. Can be granted. Moreover, when the thermosetting resin composition is cured by containing the (B) amine component, the (C) epoxy resin component described later can be efficiently cured.

The amine component (B) used in the present invention is not particularly limited. For example, monoamines such as aniline, benzylamine, and aminohexane; monomer (A-2) used in the production of the polyamic acid described above Various diamines mentioned in the diamine component; polyamines such as diethylenetriamine, tetraethylenepentamine, and pentaethylenehexamine; Moreover, as (B) amine component, it is more preferable to contain aromatic diamine among these amines. Thereby, favorable heat resistance (thermal expansion coefficient, glass transition temperature) and solder heat resistance can be imparted to the cured film.

  The aromatic diamine is not particularly limited. Specifically, for example, [4- (4-aminophenoxy) phenyl] methane, 1,1-bis [4- (3-aminophenoxy) Phenyl] ethane, 1,1-bis [4- (4-aminophenoxy) phenyl] ethane, 1,2-bis [4- (3-aminophenoxy) phenyl] ethane, 1,2-bis [4- (4 -Aminophenoxy) phenyl] ethane, 2,2-bis [4- (3-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [ Bis [(aminophenoxy) phenyl] alkanes such as 4- (3-aminophenoxy) phenyl] butane; 2,2-bis [3- (3-aminophenoxy) phenyl] -1,1,1,3 Bis [(aminophenoxy) phenyl] such as 3,3-hexafluoropropane, 2,2-bis [4- (4-aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane Fluoroalkanes; bis (aminophenoxy) benzene compounds such as 4,4′-bis (4-aminophenoxy) biphenyl; bis [4- (3-aminophenoxy) phenyl] ketone, bis [4- (4- Bis (aminophenoxy) ketone compounds such as aminophenoxy) phenyl] ketone; bis [((aminophenoxy) phenyl] sulfide, bis [(4- (4-aminophenoxy) phenyl] sulfide, etc. Aminophenoxy) phenyl] sulfide compounds; bis [4- (3-aminophenoxy) phenyl] sulfone, bi Bis [(aminophenoxy) phenyl] sulfone compounds such as [4- (4-aminophenoxy) phenyl] sulfone; bis [4- (3-aminophenoxy) phenyl] ether, bis [4- (4-aminophenoxy) Bis [(aminophenoxy) phenyl] ether compounds such as phenyl] ether; 1,4-bis [4- (3-aminophenoxy) benzoyl] benzene, 1,3-bis [4- (3-aminophenoxy) Bis [(aminophenoxy) benzoyl] benzene compounds such as benzoyl] benzene; 4,4′-bis [3- (4-aminophenoxy) benzoyl] diphenyl ether, 4,4′-bis [3- (3-amino Bis [(aminophenoxy) benzoyl] diphenyl ether such as phenoxy) benzoyl] diphenyl ether Ter compounds; benzophenone compounds such as 4,4′-bis [4- (4-amino-α, α-dimethylbenzyl) phenoxy] benzophenone; 4,4′-bis [4- (4-amino- (phenoxy) phenylsulfone compounds such as α, α-dimethylbenzyl) phenoxy] diphenylsulfone and bis [4- {4- (4-aminophenoxy) phenoxy} phenyl] sulfone; 1,4-bis [4- ( Bis [(aminophenoxy) dimethylbenzene] benzene such as 4-aminophenoxy) -α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-aminophenoxy) -α, α-dimethylbenzyl] benzene And the like. These diamines may be used alone or in combination of two or more at any ratio.

  Among these, in particular, 2,2-bis [4- (3-aminophenoxy) phenyl] propane, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, 2,2-bis [3- (3-Aminophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 2,2-bis [4- (4-aminophenoxy) phenyl] -1,1,1,3 3,3-hexafluoropropane, bis [4- (3-aminophenoxy) phenyl] sulfone, bis [4- (4-aminophenoxy) phenyl] sulfone, bis [4- (3-aminophenoxy) phenyl] ether, Bis [4- (4-aminophenoxy) phenyl] ether can be more preferably used.

  These compounds are not only preferable from the viewpoint of easy handling and availability such as being easily dissolved in a solvent, but also by containing these compounds in the (B) amine component, heat resistance (heat Various properties such as low expansion coefficient, high glass transition temperature, etc.) and solder heat resistance can be achieved.

(II-3) (C) Epoxy Resin Component The (C) epoxy resin component used in the present invention only needs to contain at least one epoxy resin. The resin composition for coverlay according to the present invention can impart good resin fluidity to the coverlay film by containing this (C) epoxy resin component, and is good for the cured film. Heat resistance and insulation can be imparted. Moreover, the favorable adhesiveness with respect to conductors and circuit boards, such as metal foil, can be provided by containing (C) an epoxy resin component.

  The epoxy resin is not particularly limited. Specifically, for example, bisphenol type epoxy resin, bisphenol A novolac type epoxy resin, biphenyl type epoxy resin, phenol novolac type epoxy resin, alkylphenol novolac type epoxy resin, and the like. , Epoxy resins such as polyglycol type epoxy resins, cycloaliphatic epoxy resins, cresol novolac type epoxy resins, glycidylamine type epoxy resins, naphthalene type epoxy resins, urethane modified epoxy resins, rubber modified epoxy resins, epoxy modified polysiloxanes; These halogenated epoxy resins; crystalline epoxy resins having a melting point; These epoxy resins may be used alone or in combination of two or more at any ratio.

  Among these epoxy resins, an epoxy resin having at least one aromatic ring and / or aliphatic ring in a molecular chain, a biphenyl type epoxy resin having a biphenyl skeleton, a naphthalene type epoxy resin having a naphthalene skeleton, and a crystalline epoxy having a melting point A resin is more preferably used. These epoxy resins are easily available and have excellent compatibility with (A), (B), and (D). Moreover, while being able to provide favorable resin fluidity | liquidity with respect to the resin composition for coverlays obtained, the outstanding heat resistance and insulation can be provided with respect to the cured resin after hardening.

  Among the above epoxy resins, the following group of formulas (3)

（ただし、式中、ｑ，ｒ，ｓはそれぞれ独立して任意の整数を示し、Ｒ２、Ｒ３はそれぞれ独立して炭素数１〜４のアルキル基を示す。）
で表されるエポキシ樹脂、または結晶性エポキシ樹脂をより一層好ましく用いることができる。これらエポキシ樹脂を用いれば、カバーレイフィルムおよび硬化後のフィルムに対して、耐熱性、回路埋め込み性等の諸特性を付与することができる上に、これら諸特性のバランスを良好なものとすることができる。

(However, in the formula, q, r, and s each independently represent an arbitrary integer, and R2 and R3 each independently represent an alkyl group having 1 to 4 carbon atoms.)
An epoxy resin represented by or a crystalline epoxy resin can be more preferably used. If these epoxy resins are used, various properties such as heat resistance and circuit embedding properties can be imparted to the coverlay film and the cured film, and the balance between these properties should be good. Can do.

In addition, it is preferable that the epoxy resin used as (C) epoxy resin component is a high purity epoxy resin, even if it is any epoxy resin mentioned above. In the resin composition for coverlays and the resin composition after curing thus obtained, highly reliable electrical insulation can be realized. In the present invention, the high purity standard is the concentration of halogen or alkali metal contained in the epoxy resin. Specifically, the concentration of halogen or alkali metal contained in the epoxy resin is preferably 25 ppm or less, more preferably 15 ppm or less when extracted under the conditions of 120 ° C. and 2 atm. . If the content concentration of halogen or alkali metal is higher than 25 ppm, the electrical insulating reliability tends to be impaired in the cured film.

  In addition, the epoxy resin used as the epoxy resin component (C) is any epoxy resin described above, and the lower limit of the epoxy value (also referred to as epoxy equivalent) is preferably 150 or more, and 170 or more. More preferably, it is most preferably 190 or more. The upper limit value of the epoxy value of the epoxy resin is preferably 700 or less, more preferably 500 or less, and most preferably 300 or less. Therefore, it is preferable that the epoxy value of the epoxy resin used as the (C) epoxy resin fraction is in the range of 150 to 700.

  When the epoxy value of the epoxy resin is less than 150, the distance between cross-linking points is shortened, so that the cured film becomes brittle and the flexibility is impaired. On the other hand, when the epoxy value exceeds 700, the distance between the crosslinking points in the cured resin becomes too long, and as a result, the heat resistance such as the glass transition temperature and the thermal expansion tends to be impaired.

(II-4) (D) Imidazole Component The (D) imidazole component used in the present invention may contain at least one imidazole. The coverlay film according to the present invention can promote the curing reaction between the (B) amine component and the (C) epoxy resin component by containing the (D) imidazole component.

  In addition, as a result of intensive studies by the present inventors, when (D) an imidazole component is further added to each of the components (A) to (C) described above, the minimum melt viscosity is obtained in the obtained coverlay film. A novel finding has been found that the value can be further reduced and the circuit embedding property can be greatly improved (that is, the resin fluidity can be further improved). Therefore, in the present invention, various properties such as excellent fluidity, heat resistance, adhesiveness, workability, and flexibility are imparted to the coverlay film before curing and the film after curing in a balanced manner. Can do.

In the coverlay film according to the present invention, the mixing ratio (blending amount) of the (D) imidazole component is not particularly limited, but the mixing is performed at a weight ratio (weight ratio) based on the (C) epoxy resin component. A preferred range of ratios can be defined. Specifically, the mixing ratio of the total amount of (D) imidazole component is preferably 0.01 parts by weight or more when the total amount of all components (A) to (C) is 100 parts by weight. , 0.05 parts by weight or more, more preferably 0.1 parts by weight or more. Moreover, the upper limit is preferably 10.0 parts by mass or less, more preferably 5.0 parts by mass or less, and particularly preferably 3.0 parts by mass or less. Therefore, the mixing ratio of the (D) imidazole component is preferably in the range of 0.01 parts by weight to 10.0 parts by weight with respect to 100 parts by weight of the components (A) to (C). (D) When the mixing ratio of the imidazole component is less than 0.01 parts by weight, not only the effect of improving circuit embedding can be obtained, but also the curing reaction of (B) amine component and (C) epoxy resin component is sufficient. Can no longer proceed. On the other hand, when the mixing ratio of (D) imidazole component exceeds 10.0 parts by weight, the curing reaction of (B) amine component and (C) epoxy resin component is promoted too much. It will greatly impair the sex.

  The imidazole used as the (D) imidazole component is not particularly limited. Specifically, for example, imidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-undecylimidazole, 1-benzyl-2-methylimidazole, 2-heptadecylimidazole, 2 -Imidazoles such as isopropylimidazole, 2,4-dimethylimidazole, 2-phenyl-4-methylimidazole; 2-methylimidazoline, 2-ethylimidazoline, 2-isopropylimidazoline, 2-phenylimidazoline, 2-undecylimidazoline 2,4-dimethylimidazoline, imidazolines such as 2-phenyl-4-methylimidazoline; 2,4-diamino-6- [2′-methylimidazolyl- (1 ′)]-ethyl-s-triazine, 2, 4-Diamino-6- [2 ' Azines such as undecylimidazolyl- (1 ′)]-ethyl-s-triazine, 2,4-diamino-6- [2′-ethyl-4′-methylimidazolyl- (1 ′)]-ethyl-s-triazine Imidazoles; and the like. These imidazoles may be used alone or in combination of two or more at any ratio.

  Among these compounds, 2-ethyl-4-methylimidazole, 2-phenyl-4-methylimidazole, 2,4-diamino-6- [2 ′] are excellent in circuit embedding property, availability, solvent solubility and the like. -Undecylimidazolyl- (1 ')]-ethyl-s-triazine is more preferably used.

(II-5) (E) Other components The coverlay film according to the present invention may contain (E) other components other than the components (A) to (D) as necessary. Good. (E) Other components are not particularly limited. Specifically, for example, (E-1) (C) epoxy resin component curing agent (other than (B) amine component), (E- 2) (C) A curing accelerator (other than (D) imidazole component) for accelerating the reaction between the epoxy resin component and the curing agent, (E-3) a thermosetting component, and the like.

<(E-1) Curing Agent>
Although it does not specifically limit as said (E-1) hardening | curing agent, Specifically, phenol resins, such as a phenol novolak type phenol resin, a cresol novolak type phenol resin, a naphthalene type phenol resin; Aliphatic acid anhydrides such as succinic acid, polyadipic acid anhydride and polyazeline acid anhydride; alicyclic acid anhydrides such as hexahydrophthalic anhydride and methylhexahydrophthalic acid; phthalic anhydride, trimellitic anhydride, benzophenone Aromatic acid anhydrides such as tetracarboxylic acid, ethylene glycol bis trimellitate, glycerol tris trimellitate; other resins such as amino resins, urea resins, melamine resins; dicyandiamide; dihydrazine compounds; Lewis acid And Bronsted acid salts; polymer caps Emissions compounds; isocyanate and blocked isocyanate compounds; and the like. These curing agents may be used alone or in combination of two or more at any ratio.

The amount of the curing agent used (mixing ratio) is not particularly limited, and (C) is an amount capable of curing the epoxy resin component and does not impair the flexibility and heat resistance of the cured film. However, in general, when the total amount of the (C) epoxy resin component is 100 parts by weight, it is preferably used within the range of 1 to 100 parts by weight.

<(E-2) Curing accelerator>
The (E-2) curing accelerator is not particularly limited. Specifically, for example, a phosphine compound such as triphenylphosphine; a tertiary amine system, trimethanolamine, triethanolamine, Examples thereof include amine compounds such as tetraethanolamine; borate compounds such as 1,8-diaza-bicyclo [5,4,0] -7-undecenium tetraphenylborate. These curing accelerators may be used alone or in combination of two or more at any ratio.

  The amount (mixing ratio) of these curing accelerators is not particularly limited, and may be any amount that can accelerate the reaction between the epoxy resin component and the curing agent. Generally, (A) to (A C) When the total amount is 100 parts by weight, it is preferably used within the range of 0.001 to 10 parts by weight.

<(E-3) thermosetting component>
The (E-3) thermosetting component is not particularly limited, but specifically, for example, bismaleimide resin, bisallyl nadiimide resin, acrylic resin, methacrylic resin, hydrosilyl cured resin, allyl cured Thermosetting resin such as resin and unsaturated polyester resin; Side chain reactive group type thermosetting having reactive groups such as allyl group, vinyl group, alkoxysilyl group, hydrosilyl group at the side chain or terminal of polymer chain Polymer; etc. can be used. These thermosetting components may be used alone or in combination of two or more at any ratio. By adding these thermosetting components, various properties such as adhesiveness, heat resistance, and workability can be improved in the obtained coverlay film and the cured film.

  In addition, it does not specifically limit about the usage-amount (mixing ratio) of the said thermosetting component, What is necessary is just the quantity which can exhibit the improvement effect of various characteristics.

(III) Production of coverlay film according to the present invention The coverlay film according to the present invention can be suitably used for various applications, and among them, it can be suitably used as a material for a flexible printed wiring board. Specifically, it can be suitably used as a protective material for protecting the circuit board or a patterned circuit on the circuit board.

<Resin solution>
In the present invention, a method for producing a coverlay film is not particularly limited, and examples thereof include a method of applying a resin solution (varnish) to a circuit board. The method for preparing the resin solution is not particularly limited, and the thermosetting resin composition according to the present invention may be added to an appropriate solvent and stirred. Alternatively, the components (A) to (E) described above may be dissolved in an appropriate solvent to prepare a solution for each component, and these may be mixed. The solution according to component at this time may contain only each component of (A)-(E), and may contain two or more types of components. Moreover, even if it is the same component, when using multiple types of compounds, you may prepare a solution about each. For example, when two types of polyimide resins are used as the (A) polyimide resin component, the respective polyimide resins may be prepared and mixed as a solution.

  The solvent that can be used for the resin solution is not particularly limited as long as it is a solvent that can dissolve the thermosetting resin composition or each of the components (A) to (E). The following solvents are preferable. Specifically, for example, cyclic ethers such as tetrahydrofuran, dioxolane and dioxane; ethers such as chain ethers such as ethylene glycol dimethyl ether, triglyme, diethylene glycol, ethyl cellosolve and methyl cellosolve; and the like are preferably used. In addition, a mixed solvent obtained by mixing these ethers with toluene, xylenes, glycols, N, N-dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone, cyclic siloxane, chain siloxane, etc. is also preferably used. Can do. These solvent may use only 1 type and may use it combining 2 or more types by arbitrary ratios.

  The resin solution thus obtained may be applied directly on the circuit wiring, dried and cured, and a layer to be a coverlay film may be formed on the circuit board wiring.

<Resin film>
Moreover, as for the coverlay film concerning this invention, laminated bodies, such as a 2 layer film or a 3 layer film which provide a coverlay film on the single side | surface or both surfaces of the resin composition base material, can be mentioned. Therefore, the present invention includes not only a single layer cover lay film but also a laminate comprising at least one resin layer formed using the cover lay film.

The method for forming the coverlay film is not particularly limited. Usually, the resin solution is cast or coated on the surface of the film substrate (support), and then the resin solution is dried to form a film. It may be formed into In addition, when drying, it is preferable to dry while suppressing the curing reaction of the thermosetting component. Specifically, the drying is performed at a temperature of 180 ° C. or lower, more preferably 150 ° C. or lower and within 10 minutes or less. In addition, the solvent that can be used for the resin solution is not particularly limited as long as it is a solvent that can dissolve the thermosetting resin composition or each of the components (A) to (E). A solvent having a boiling point of 150 ° C. or lower is preferable. Specifically, for example, cyclic ethers such as tetrahydrofuran, dioxolane and dioxane; ethers such as chain ethers such as ethylene glycol dimethyl ether, triglyme, diethylene glycol, ethyl cellosolve and methyl cellosolve; and the like are preferably used. In addition, a mixed solvent obtained by mixing these ethers with toluene, xylenes, glycols, N, N-dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone, cyclic siloxane, chain siloxane, etc. is also preferably used. Can do. These solvent may use only 1 type and may use it combining 2 or more types by arbitrary ratios.

  In this coverlay film, the film is in a semi-cured state (B stage state). Therefore, if the semi-cured film is peeled from the support, the single-layer film can be obtained. If the film is not peeled off, a two-layer film composed of a film substrate and a coverlay film can be obtained. The coverlay film that is in a semi-cured state has a minimum melt viscosity of 100 poise or more and 80000 poise or less under the condition that the temperature is in the range of 60 ° C. or more and 200 ° C. or less. From the viewpoint of embedding property and thickness control of the coverlay film layer after lamination.

Furthermore, if a resin solution is cast or applied on both surfaces of a film substrate, and then the resin solution is dried, a three-layer film comprising the film substrate and the resin layers on both surfaces thereof can be obtained.
Moreover, the said multilayer film can be manufactured by repeating the process of casting or apply | coating the said resin solution on the surface of the said film base material, and drying a resin solution after that.

The kind of film base material used as the support is not particularly limited, and a known resin film can be suitably used. Moreover, when manufacturing a single layer film, you may use support bodies other than a film base material. Examples of such a support include a drum and an endless belt.

  Whether the coverlay film according to the present invention is used as a single layer film or a laminate, the thickness of the coverlay film is not particularly limited. The thickness of the non-film may be set to an appropriate thickness according to the purpose of use.

  Furthermore, the resin composition for coverlay according to the present invention can be impregnated with various fibers such as glass cloth, glass mat, aromatic polyamide fiber cloth, and aromatic polyamide fiber mat, for example. If the resin composition component for coverlay impregnated in the fiber is semi-cured, a fiber-reinforced coverlay film can be obtained.

  By laminating the cover lay film thus obtained on the surface of the circuit board on which the circuit wiring is formed, the circuit board in which the circuit is protected by the cover lay film can be manufactured. I can do it. An example of the lamination condition is described in <Circuit board> below.

  The cured film preferably has a thermal expansion coefficient of 20 ppm or less at 20 ° C to 100 ° C.

<Circuit board>
The coverlay resin composition of the present invention has appropriate fluidity. Therefore, by performing thermocompression treatment such as hot press treatment, laminating treatment (thermal laminating treatment), hot roll laminating treatment, the space between the pattern circuits can be satisfactorily embedded with resin. Although the processing temperature in the said thermocompression bonding process is not specifically limited, It is preferable that it exists in the range of 50 degreeC or more and 200 degrees C or less, It is more preferable that it exists in the range of 60 degreeC or more and 180 degrees C or less, 80 degreeC. It is preferably within the range of 130 ° C. or lower. If the treatment temperature exceeds 200 ° C., the resin layer may be cured during the thermocompression treatment. On the other hand, when the processing temperature is less than 50 ° C., the fluidity of the resin layer is low, and it becomes difficult to embed the pattern circuit.

  In the case of curing the resin composition for coverlay, in order to sufficiently advance the curing reaction of the epoxy resin component (C), after the coverlay resin composition and the circuit board are bonded together, post heat treatment is performed. It is preferable to implement. The conditions for the post heat treatment are not particularly limited, but it is preferable to perform the heat treatment for 10 minutes to 3 hours under temperature conditions in the range of 150 ° C. to 200 ° C.

  Moreover, as a circuit board using the resin composition for coverlays of the present invention, in terms of heat resistance, the base film is a flexible film made of any one of a polyimide film, an aramid film, a polyethylene terephthalate film, and a polyethylene naphthalate film. A circuit board is preferred.

  As described above, the cover lay film according to the present invention can realize various characteristics such as excellent heat resistance (low linear expansion coefficient), adhesiveness, workability, solder heat resistance, and flexibility in a balanced manner. In particular, the coverlay film of the present invention has excellent flexibility, which is an important characteristic for the coverlay film. Regarding the flexibility, it is preferable that the flexibility measured by an MIT fatigue resistance tester is 10 times or more. Preferably it is 20 times or more and 50 times or more.

  The coverlay film of the present invention makes it possible to suitably manufacture a high-quality circuit board. In particular, the electrical reliability of each circuit can be ensured.

  The present invention will be described more specifically based on examples, but the present invention is not limited to this. Those skilled in the art can make various changes, modifications, and alterations without departing from the scope of the present invention. In addition, the fluidity | liquidity and lamination property of the resin composition for coverlays concerning this invention were evaluated as follows. Moreover, the glass transition temperature, the thermal expansion coefficient, the flexibility, and the solder heat resistance of the cured resin composition obtained by heat-curing the coverlay resin composition were measured and evaluated as follows.

〔Liquidity〕
Using a shear mode dynamic viscoelasticity measuring device (CVO, manufactured by Bohling), the resin sheet before heat curing is measured for the complex viscosity (Pa · S) under the following conditions, and the melt viscosity (poise) is calculated from the complex viscosity. ). The melt viscosity of each resin sheet was evaluated at the lowest melt viscosity within a temperature range of 60 ° C. or higher and 200 ° C. or lower.
Measurement frequency: 1Hz
Temperature rising rate: 12 ° C./min Measurement sample: Circular resin sheet with a diameter of 3 mm [Laminating property]
A flexible printed wiring board having a circuit in which a height is 18 μm, a circuit width (L) is 25 μm, an inter-circuit distance (S) is 25 μm, and L and S are alternately repeated 5 times (base material: 25 μm polyimide film, The circuit forming surface of Kaneka Co., Ltd. (apical NPI) and the resin composition for coverlay (25 μm thickness) of the resin composition for coverlay with a release film are in contact with each other at a temperature of 180 ° C. and a pressure of 1.5 MPa. The laminate was obtained by heating and pressing for 1 hour. The release film was peeled off from the obtained laminate, and was visually observed using an optical microscope (magnification 50 times) from the resin composition for coverlay, and the presence or absence of bubbles in between the circuits was confirmed.

  The stacking property when the encroachment of bubbles between the circuits (the portion where the resin does not enter between the circuits) is not confirmed is accepted (O), and the laminating property when the entrapment of bubbles is confirmed is rejected ( Evaluation was carried out as x).

〔Glass-transition temperature〕
Using DMS-200 (product number, manufactured by Seiko Denshi Kogyo Co., Ltd.), the measurement length (measurement jig interval) is 20 mm, and the storage elastic modulus (ε ′) of the cured resin sheet is measured under the following conditions. The inflection point of the storage elastic modulus (ε ′) was defined as the glass transition temperature (° C.).
Measurement atmosphere: Under dry air atmosphere
Measurement temperature: 20 ° C to 400 ° C
Measurement sample: Film after curing (single layer) slit to 9 mm width and 40 mm length
[Coefficient of thermal expansion]
The thermal expansion coefficient was measured using TMA-50 (trade name, manufactured by Shimadzu Corporation) under the following conditions, and the average thermal expansion coefficient between 30 ° C. and 125 ° C. in the measurement result was defined as the thermal expansion coefficient of the sample. .
Measurement method: Tensile mode (adjusted so that the load applied to the sample is 3 g)
Temperature increase rate: 10 ° C./min Measurement range: 30 ° C. to 300 ° C.
Measurement atmosphere: Nitrogen (flow rate 50 ml / min)
Measurement sample: A sample obtained by heating a cured film (single layer) at 250 ° C. for 1 minute in order to alleviate distortion at the time of curing was used.
Sample shape: width 5 mm x thickness 50 μm
Distance between measurements (distance between chucks): 15 mm
[Flexibility (MIT)]
Flexibility was measured on a cured film (single layer) using an MIT fatigue resistance tester MIT-D (trade name, Toyo Seiki Seisakusho Co., Ltd.) according to ASTM-D2176. The load tip R was 0.38 mm, the load was 500 g / mm ² , and bending was performed at 135 ° to the left and right, and the number of bending until the film was broken was measured.

[Solder heat resistance]
The evaluation of solder heat resistance was performed by using the sample prepared in the evaluation of the laminate property and performing heat treatment three times under the following conditions using IR reflow (product number; FT04, manufactured by CIF).
Evaluation sample size: 15 mm x 30 mm
Setting conditions: (Conditions based on JEDEC Level3)
P0: 100 ° C./0.2 min
P1: 165 ° C / 1.3min
P2: 200 ° C / 1.3min
When the sample after heating is visually observed and blistering occurs, it is rejected (x). The case where there was no blistering was determined to be a pass (◯).

[Synthesis Example of Polyimide Resin A]
In a glass flask having a volume of 2000 ml, 0.95 equivalent of 1,3-bis (3-aminophenoxy) benzene (APB) and 0.05 equivalent of 3,3′-dihydroxy-4,4 in dimethylformamide (DMF). '-Diaminobiphenyl (manufactured by Wakayama Seika Kogyo Co., Ltd.) was charged and stirred to dissolve in a nitrogen atmosphere to obtain a DMF solution. Subsequently, the inside of the flask was placed under a nitrogen atmosphere, and the DMF solution was stirred while being cooled with ice water, and 1 equivalent of 4,4 ′-(4,4′-isopropylidenediphenoxy) bisphthalic anhydride (IPBP, GE) was added. Then, the polyamic acid solution was obtained by further stirring for 3 hours. In addition, the usage-amount of the said DMF was set so that the preparation density | concentration of the monomer of APB, 3,3'- dihydroxy-4,4'-diaminobiphenyl and IPBP might be 30 weight%.

  By transferring 300 g of the polyamic acid solution to a vat coated with a fluororesin and heating in a vacuum oven under reduced pressure for 3 hours under the conditions of 200 ° C. and 5 mmHg (about 0.007 atm, about 5.65 hPa). The polyimide resin A was obtained.

[Example 1]
Each component shown below was dissolved in dioxolane so as to have a mixing ratio shown in Table 1 to obtain a resin solution (varnish) as a resin composition for coverlay according to the present invention.
(A) Polyimide resin component: polyimide resin obtained by the above synthesis example (B) Amine component: bis [4- (4-aminophenoxy) phenyl] sulfone (BAPS
, Molecular weight = 432 g / eq, manufactured by Wakayama Seika Kogyo Co., Ltd.)
(C) Epoxy resin component: bisphenol A type epoxy resin E1001, epoxy value = 470 g / eq, manufactured by Japan Epoxy Resin Co., Ltd.)
(D) Imidazole component: 2,4-diamino-6- [2′-undecylimidazolyl- (
1 ′)]-Ethyl-s-triazine (trade name: Curezol C11Z-A, manufactured by Shikoku Chemicals Co., Ltd.)
The obtained resin solution was cast on the surface of a 125 μm-thick PET film (trade name Therapy HP, manufactured by Toyo Metallizing Co., Ltd.) which is a support (release film). Then, it heat-dried for 1 minute each at the temperature of 60 degreeC, 80 degreeC, 100 degreeC, 120 degreeC, and 140 degreeC with a hot air oven, and obtained the 2 layer film which uses a PET film as a film base material. A single layer film (resin film before heat curing) was obtained by peeling and removing the PET film from the two-layer sheet. The thickness of the obtained resin film was 25 μm. The resin fluidity and laminateability of the obtained resin sheet were evaluated. The results are shown in Table 3.

Next, the above-mentioned resin film is sandwiched between 18 μm rolled copper foil (trade name: BHY-22B-T, manufactured by Japan Energy Co., Ltd.) so as to be in contact with the copper foil roughened surface of the rolled copper foil. It is. Then, the copper foil laminated body (metal layer containing laminated body) of the structure which pinched | interposed the resin film with the rolled copper foil was obtained by heat-pressing for 1 hour on the conditions of temperature 180 degreeC and pressure 1.5MPa. The copper foil of the obtained copper foil laminate was removed by etching to obtain a film after curing. The glass transition temperature, thermal expansion coefficient, flexibility, and solder heat resistance of the obtained cured film were measured. The results are shown in Table 4.

[Examples 2 to 6]
The coverlay film (before heat curing) and the coverlay resin composition are cured in the same manner as in Example 1 except that the components (A) to (D) are mixed in the ratios shown in Table 1. A film after curing was obtained. In Table 1, E1001 (trade name, manufactured by Japan Epoxy Resin Co., Ltd.) is a bisphenol A type epoxy resin. BAPS (manufactured by Wakayama Seika Kogyo Co., Ltd.) refers to bis [4- (4-aminophenoxy) phenyl] sulfone. Furthermore, C11Z-A (trade name, manufactured by Shikoku Kasei Kogyo Co., Ltd.) is 2,4-diamino-6- [2′-undecylimidazolyl- (1 ′)]-ethyl-s-triazine.

  About the obtained resin composition for coverlays, fluidity | liquidity and lamination | stacking property were evaluated, and the glass transition temperature, the thermal expansion coefficient, the flexibility, and the solder heat resistance were evaluated about the resin composition after hardening. The results are shown in Tables 3 and 4.

〔比較例１〜４〕
（Ａ）〜（Ｄ）の各成分を表２に示す比率で混合した以外は、実施例１と同様の手法で
、カバーレイ用樹脂組成物（加熱硬化前）、当該カバーレイ用樹脂組成物を硬化させてなる硬化後樹脂組成物を得た。得られたカバーレイ用樹脂組成物について、流動性、積層性を評価し、硬化後樹脂組成物について、ガラス転移温度、熱膨張係数、屈曲性、半田耐熱性を評価した。その結果を表３および表４に示す。なお、表２において、Ｅ１００１（商品名、ジャパンエポキシレジン（株）製）は、ビスフェノールＡ型エポキシ樹脂である。また、ＢＡＰＳ（和歌山精化工業（株）製）は、ビス［４−（４−アミノフェノキシ）フェニル］スルホンを指し、ＴＤ−２１３１（商品名、大日本インキ工業(株）社製）は、フェノールノボラック型フェノール樹脂を指す。さらに、Ｃ１１Ｚ−Ａ（商品名、四国化成工業（株）製）は、２,４−ジアミノ−６−［２’−ウンデシルイミダゾリル−（１’）］−エチル−ｓ−トリアジンである。

[Comparative Examples 1-4]
A resin composition for coverlay (before heat curing) and the resin composition for coverlay, in the same manner as in Example 1, except that the components of (A) to (D) were mixed at the ratio shown in Table 2 After curing, a cured resin composition was obtained. About the obtained resin composition for coverlays, fluidity | liquidity and lamination | stacking property were evaluated, and the glass transition temperature, the thermal expansion coefficient, the flexibility, and the solder heat resistance were evaluated about the resin composition after hardening. The results are shown in Tables 3 and 4. In Table 2, E1001 (trade name, manufactured by Japan Epoxy Resin Co., Ltd.) is a bisphenol A type epoxy resin. BAPS (manufactured by Wakayama Seika Kogyo Co., Ltd.) refers to bis [4- (4-aminophenoxy) phenyl] sulfone, and TD-2131 (trade name, manufactured by Dainippon Ink Industries, Ltd.) Phenol novolac type phenol resin. Furthermore, C11Z-A (trade name, manufactured by Shikoku Kasei Kogyo Co., Ltd.) is 2,4-diamino-6- [2′-undecylimidazolyl- (1 ′)]-ethyl-s-triazine.

上記の結果から明らかなように、本発明にかかるカバーレイ用樹脂組成物は、（Ａ）ポリ
ミド樹脂成分、（Ｂ）アミン成分、（Ｃ）エポキシ樹脂成分に加えて、（Ｄ）イミダゾール成分を含んでおり、（Ｂ）アミン成分と（Ｃ）エポキシ樹脂成分との合計重量に対する上記（Ａ）ポリイミド樹脂成分の重量混合比（Ａ）／［（Ｂ）＋（Ｃ）］を規定すれば、得られるカバーレイ用樹脂組成物および硬化後樹脂組成物に対して、耐熱性、接着性、加工性、屈曲性を優れたものとできるだけでなく、プレッシャークッカーによる耐湿性テスト耐性（ＰＣＴ耐性）、絶縁性等の諸特性についても優れたものとすることができ、かつ、これら諸特性のバランスを良好なものとすることができる。

As is clear from the above results, the resin composition for coverlay according to the present invention comprises (D) an imidazole component in addition to (A) a polyimide resin component, (B) an amine component, and (C) an epoxy resin component. If the weight mixing ratio (A) / [(B) + (C)] of the (A) polyimide resin component to the total weight of the (B) amine component and the (C) epoxy resin component is specified, In addition to having excellent heat resistance, adhesiveness, workability, and flexibility for the resin composition for coverlay and the resin composition after curing, the moisture resistance test resistance (PCT resistance) by pressure cooker, Various characteristics such as insulation can be made excellent, and the balance between these characteristics can be made good.

  The present invention is not limited to the configurations described above, and various modifications can be made within the scope of the claims, and technical means disclosed in different embodiments and examples can be used. Embodiments obtained by appropriate combinations are also included in the technical scope of the present invention.

  As described above, the resin composition for coverlay according to the present invention not only has excellent heat resistance, adhesiveness, workability, and flexibility, but also moisture resistance test resistance (PCT resistance) by pressure cooker, insulation. Various characteristics such as properties can also be made excellent, and the balance of these characteristics can be made good. Therefore, it can be suitably used for the production of a flexible printed wiring board. Therefore, the present invention can be suitably used not only in the material processing industry such as resin compositions and adhesives and various chemical industries, but also in the industrial field of various electronic components.

Claims (11)

A coverlay film for laminating on a surface of a circuit board on which a circuit is formed, wherein the coverlay film comprises (A) a polyimide resin component containing at least one polyimide resin and at least one amine. (B) an amine component, (C) an epoxy resin component containing at least one epoxy resin, and (D) an imidazole component containing at least one imidazole. C) The weight mixing ratio (A) / [(B) + (C)] represented by the weight of the (A) polyimide resin component with respect to the total weight with the epoxy resin component is 0.4 to 2.0. A coverlay film comprising a resin composition within a range. The coverlay film is in a semi-cured state, and the minimum melt viscosity is in the range of 100 poise or more and 80,000 poise or less under the condition that the temperature is in the range of 60 ° C. or more and 200 ° C. or less. The cover lay film according to claim 1. The coverlay film according to claim 1 or 2, wherein the cured film has a coefficient of thermal expansion at 20 ° C to 100 ° C of 80 ppm or less. The coverlay film according to any one of claims 1 to 3, wherein the flexibility measured by an MIT fatigue resistance tester is 10 times or more. The molar mixing ratio (B) / (C) represented by the number of moles of active hydrogen contained in the (B) amine component with respect to the number of moles of the epoxy group of the epoxy resin contained in the (C) epoxy resin component is: The coverlay film according to any one of claims 1 to 4, wherein the coverlay film is in a range of 0.4 to 2.0. The at least one polyimide resin contained in the (A) polyimide resin component is represented by the general formula (1).

(Wherein, X ₁ is a divalent group selected from the group consisting of direct bond, —O—, —CO—, —O—X ₂ —O—, and —COO—X ₂ —OCO—. And X ₂ represents a divalent organic group) (A-1) comprising at least one acid dianhydride having a structure represented by (A-1) and at least one diamine The coverlay film according to any one of claims 1 to 5, wherein the coverlay film is obtained by reacting (A-2) a diamine component. The coverlay film according to any one of claims 1 to 6, wherein the circuit board is formed with a circuit whose line / space is in the range of 1 µm to 35 µm. The said circuit board is a flexible circuit board which uses as a base film the film selected from a polyimide film, an aramid film, a polyethylene terephthalate film, and a polyethylene naphthalate film. The coverlay film described in 1. A circuit board using the coverlay film according to any one of claims 1 to 7. The circuit board according to claim 8, wherein the circuit board is a flexible circuit board having a film selected from a polyimide film, an aramid film, a polyethylene terephthalate film, and a polyethylene naphthalate film as a base film. A resin composition solution for applying to a surface of a circuit board on which a circuit is formed and drying to form a coverlay film, comprising (A) a polyimide resin component containing at least one polyimide resin, and at least one kind (B) an amine component containing amines, (C) an epoxy resin component containing at least one epoxy resin, and (D) an imidazole component containing at least one imidazole. The weight mixing ratio (A) / [(B) + (C)] represented by the weight of the (A) polyimide resin component with respect to the total weight of the component and the (C) epoxy resin component is 0.4 or more. A resin composition solution characterized by being in a range of 0 or less.