JP4500091B2 - Circuit board - Google Patents

Description

  The present invention relates to a circuit board used in the field of electronic materials such as a semiconductor substrate, and more particularly to a build-up type circuit board in which insulating layers and conductive layers are alternately stacked, and contains a halogen-containing flame retardant and a phosphorus-containing flame. The present invention relates to a circuit board in which a conductive layer is formed by electroless plating, which does not include a flame retardant and can be made into fine wiring and high impedance accuracy.

  In the field of electronic materials, flame retardancy is required to ensure fire safety. As for typical laminated board materials for printed wiring boards and semiconductor substrates, Underwriters Laboratories Inc. UL94 standard is required, and it is required to pass the condition of V-1, more preferably V-0, in the vertical combustion test. All the resins used in the field so far contain a halogen-containing compound such as a bromine-containing compound as a flame retardant in order to pass this condition. These halogen-containing compounds have high flame retardancy. For example, aromatic bromine compounds not only generate corrosive bromine and hydrogen bromide by thermal decomposition, but also form highly toxic compounds in the presence of oxygen. There is a possibility (see Non-Patent Document 1).

  For these reasons, materials that do not contain halogen compounds, so-called “halogen-free” materials, have been researched and developed (see, for example, Patent Document 1). Among them, phosphorus-containing compounds such as red phosphorus have been mainly studied as flame retardants replacing halogen-containing compounds. However, phosphorus-containing flame retardants may generate toxic phosphorus compounds such as phosphine during combustion, and when a typical phosphate ester is used as a phosphorus-containing compound flame retardant, the moisture resistance of the composition is significantly impaired. There are drawbacks.

  On the other hand, metal hydroxides are known as other flame retardants. For example, aluminum hydroxide is known to have an effect as a flame retardant by the following reaction that releases crystal water when heated.

2Al (OH) ₃ → Al ₂ O ₃ + 3H ₂ O
However, when a metal hydroxide such as aluminum hydroxide is used alone as a flame retardant, a large amount of addition is necessary to obtain the required flame retardant performance. In the case of a laminate using a general epoxy resin and aluminum hydroxide added as a flame retardant, the amount of aluminum hydroxide required to achieve the UL94 standard V-0 level is Even when a resin having a skeleton that hardly burns, such as about 70 wt% to 75 wt%, it is often necessary to add about 50 wt% of aluminum hydroxide (see Non-Patent Document 2). When the amount of aluminum hydroxide added is large, the performance of the circuit board having the resin composition and the insulating layer formed of the resin, particularly the chemical resistance against acids and alkalis, tends to be remarkably lowered. Since circuit processing such as etching and plating is performed under severe acidic and alkaline conditions, the reliability of the circuit board having an insulating layer with poor chemical resistance is not sufficient, and improvement is required.

On the other hand, in the field of electronic components that are required to be light and thin, high density and fine wiring are required, and high impedance control accuracy for high speed is required. In order to control the impedance with high accuracy, the flatness of the formed circuit, the shape characteristics of the circuit cross section expressed by the etching factor, etc. need to be good. As a method for forming such a circuit, there is a circuit formation by electroless plating using a plating resist (see Patent Document 2). Electroless plating circuit formation is generally performed in a highly alkaline aqueous solution at a high temperature for a long time. When a circuit is formed on a circuit board having an insulating layer with reduced chemical resistance, the circuit is eroded. Ingredients in the insulating layer thus generated contaminated the plating solution, the adhesive strength between the plated conductor layer and the insulating layer was weak, or the heat resistance of the formed circuit board was insufficient.
Hitoshi Nishizawa, “Halogen Flame Retardant”, Flame Retardant Polymer, Taiseisha, pp. 69-79 (1992) JP 2003-231762 A Yukihiro Kiuchi, Masatoshi Doji, Journal of Japan Institute of Electronics Packaging 5 (2) pp. 159-165 (2003) JP 2003-309358 A

  An object of the present invention is to provide a circuit board on which a conductive layer is formed by electroless plating which is halogen-free and phosphorus-free and has good chemical resistance.

  As a result of intensive investigations to solve the above problems, the present invention provides a circuit board in which a conductive layer is formed by electroless plating, wherein the insulating layer for electroless plating substantially contains halogen atoms and phosphorus atoms. The present inventors have found that it is possible to provide a material having sufficient flame retardancy and excellent chemical resistance even if not required.

That is, the present invention relates to the following.
1) A circuit board in which a conductive layer is formed by electroless plating, wherein the insulating layer to which electroless plating is applied is substantially free of halogen elements, and preferably 2) The circuit board according to 1), wherein the insulating layer to which electroless plating is applied further does not substantially contain phosphorus element, more preferably,
3) The resin composition forming the insulating layer to be electrolessly plated contains 2.0% or more of a compound having a maleimide group in terms of nitrogen with respect to the total mass of the resin 1) or 2) The circuit board according to 1), more preferably 4) The circuit according to 1) to 3), wherein the resin composition forming the insulating layer to be subjected to electroless plating contains aluminum hydroxide. substrate.

  In the circuit board of the present invention, a conductive layer is formed by electroless plating, and the insulating layer to which electroless plating is applied can meet the demand for flame retardancy while being halogen-free and phosphorus-free, and high It has chemical resistance. Therefore, the plating solution is not contaminated during circuit formation by electroless plating that requires severe conditions of high temperature and high alkalinity, and the heat resistance of the circuit board to be formed is sufficient.

Hereinafter, the present invention will be described in detail.
The circuit board of the present invention is characterized in that a conductive layer is formed by electroless plating, and the insulating layer to which electroless plating is applied substantially does not contain a halogen element. Here, substantially not containing a halogen element means that the content of the halogen element in the insulating layer is 0.09% by weight or less in accordance with the definition of halogen-free by the Japan Printed Circuit Industry Association. . Preferably it is 0.009 weight% or less, More preferably, it is 0.001 weight% or less.

  In the circuit board of the present invention, it is preferable that the insulating layer to be electrolessly plated does not further contain a phosphorus element. Containing substantially no phosphorus element also means that the content of phosphorus element in the insulating layer is 0.09% by weight or less in accordance with the above-mentioned definition of halogen-free. The content of the phosphorus element in the insulating layer is more preferably 0.009% by weight or less, and still more preferably 0.001% by weight or less.

  The circuit board of the present invention is preferably formed by a build-up method in which an inner layer substrate on which a circuit is formed in advance is used, and insulating layers and conductive layers are alternately laminated thereon. The inner layer substrate is preferably a substrate in which a circuit is formed on one or both sides of the insulating layer, and is not particularly limited. Although there is no restriction | limiting in particular as a material of an insulating layer, For example, well-known board | substrates, such as a glass epoxy board | substrate, a polyimide board | substrate, a bismaleimide triazine board | substrate, a thermosetting polyphenylene ether board | substrate, can be used. Further, the surface of the conductor portion of the circuit board may be subjected to a roughening process or the like in advance.

  In the circuit board of the present invention, the insulating layer may be formed on the inner layer substrate using a known method, and is not particularly limited. Specifically, for example, a method of using a prepreg in which a substrate is impregnated with a resin, a method of using an interlayer insulating sheet in which a resin is applied on a film such as a release film, or an interlayer insulating sheet on one or both sides of a prepreg Examples include a method using a laminated composite interlayer insulating material.

  As a specific example of using a prepreg, after laminating a prepreg on an inner layer substrate, a copper foil is disposed on the outermost layer, and pressing is performed under heating and pressure conditions, and after the insulating layer is cured, the copper foil For example, a method of forming an insulating layer by removing can be used. In order to improve the adhesive strength between the conductive layer formed by electroless plating and the insulating layer subjected to electroless plating, it is preferable to adjust the surface roughness of the insulating layer. Therefore, when laminating the prepreg on the inner layer substrate, the surface roughness of the insulating layer to be formed is set to a desired level by changing the surface roughness of the copper foil disposed on the outermost layer in contact with the insulating layer. be able to. The processing conditions under heating / pressurizing conditions are not particularly limited, but the heating temperature is preferably 100 to 300 ° C, more preferably 150 to 250 ° C, and the pressure is preferably 1.0. About 10 to 10 MPa, and the heating and pressing time is about 10 to 300 minutes.

  As a specific example of using an interlayer insulating sheet, an interlayer insulating sheet is laminated on an inner layer substrate so that a release film is placed on the outside, and laminated under a heating / pressurizing condition in a vacuum laminator or the like. And a method of curing the resin to form an insulating layer by heating. In order to adjust the surface roughness of the insulating layer, it is possible to dissolve the soluble components in the insulating sheet by dipping in the acid / oxidant solution after forming the insulating layer, so that the surface roughness becomes a desired level. it can. The conditions for heat curing are preferably 150 ° C. or more and less than 250 ° C., and preferably in the range of about 30 minutes to 2 hours.

  As a specific example in the case of using a composite interlayer insulation material, an interlayer insulation sheet formed by placing an interlayer insulation sheet on one or both sides of a prepreg and press-bonding with a roll laminator or the like under heat and pressure is used as an inner layer. A method in which a release film is placed and laminated on the substrate, laminated under a heating / pressurizing condition in a vacuum laminator, etc., and then heated to cure the resin and form an insulating layer, etc. Is mentioned. As a method for adjusting the surface roughness of the insulating layer, a method in which soluble components in the insulating sheet are dissolved by dipping in an acid / oxidant solution after the insulating layer is formed, and the surface roughness is adjusted to a desired level. Is mentioned. The heat curing conditions are preferably in the range of 30 minutes to 2 hours under conditions of 150 ° C. or more and less than 250 ° C.

  In the circuit board of the present invention, through holes and via holes for interlayer connection can be formed at arbitrary positions of the insulating layer formed on the inner layer substrate. A known method can be used to form the through hole or the via hole. Specifically, the hole can be formed by a drill and / or a laser.

  In order to remove smear in through holes or via holes, and when an interlayer insulating sheet is used, it is preferable to perform desmear treatment and roughening treatment in an acid / oxidant solution in order to further roughen the surface of the insulating layer. . A known roughening method can be used. Specifically, a permanganate, a dichromate, a mixed solution of hydrogen peroxide and sulfuric acid, an acid / oxidizer solution such as nitric acid, or the like is used. Roughening treatment can be performed.

  Next, it is preferable to form a plating resist layer. As the plating resist layer, a permanent resist such as photosensitive polyimide may be used, or a peelable resist layer may be used. Thereafter, electroless plating is performed to form a conductor layer, whereby an additive circuit can be formed. In the circuit board of the present invention, a semi-additive circuit can be formed by further using electrolytic plating on the conductive layer formed by electroless plating. After the conductor layer is formed, the resin composition is preferably heat treated at 150 ° C. to 250 ° C. for about 15 minutes to 90 minutes, thereby promoting the curing of the resin composition and improving heat resistance and peel strength.

  The metal species to be electrolessly plated is not particularly limited, but is preferably made of copper, silver, gold or the like. As the electroless plating method, a known method can be used, and there is no particular limitation. However, it is preferable to substitute plating plating after depositing a plating seed such as Pd on the surface of the insulating layer, or oxidation / reduction. Examples thereof include reduction plating in which plating is electrically deposited using a reaction.

  The circuit board of the present invention has a conductive layer formed by electroless plating. As a resin composition for forming an insulating layer to be electrolessly plated, the circuit board of the present invention has a conductive layer formed by electroless plating. The insulating layer to be electrolessly plated is substantially free of halogen atoms, more preferably substantially free of phosphorus atoms, yet can meet the demand for flame retardancy and is high It has chemical resistance.

  Hereinafter, preferred examples of the resin composition for forming an insulating layer to be subjected to electroless plating on the circuit board of the present invention will be described in detail.

  The resin composition for forming an insulating layer to be electrolessly plated on the circuit board of the present invention preferably contains 2.0% or more of a compound having a maleimide group in terms of nitrogen with respect to the total mass of the resin component. . More preferably, they are 3.0% or more and 7.5% or less, More preferably, they are 4.0% or more and 7.0% or less. Preferable specific examples satisfying this include (A) a compound containing at least two maleimide groups.

(A) Compound containing at least two maleimide groups The compound containing at least two maleimide groups used in the present invention is not particularly limited as long as it is a compound having at least two maleimide groups. Is a compound represented by the following general formula (1).

In the formula, R1 represents an m-valent organic group. m is an integer greater than or equal to 2, Preferably it is 2-10. Preferred examples of the organic group represented by R1 include those selected from the group consisting of the following general formulas (2-1) to (2-3).

(In the formula, Xs may be the same or different from each other, and —CH ₂ —, —C (CH ₃ ) ₂ —, —C (C ₂ H ₅ ) ₂ —, —CO—, —O—, — ( single bond), - indicating the shown .Y may be the same or different from each _{other, -CH 3, -CH 2 CH 3} , or a hydrogen atom) - S- or -SO _2.

  Specific examples of the compound containing at least two or more maleimide groups that can be used in the present invention include, for example, N, N ′-(1,3-phenylene) bismaleimide, N, N ′-[1,3- (2-Methylphenylene)] bismaleimide, N, N ′-(1,4-phenylene) bismaleimide, bis (4-maleimidophenyl) methane, bis (3-methyl-4-maleimidophenyl) methane, bis (4 -Maleimidophenyl) ether, bis (4-maleimidophenyl) sulfone, bis (4-maleimidophenyl) sulfide, bis (4-maleimidophenyl) ketone, 1,4-bis (maleimidomethyl) benzene, 1,3-bis ( 3-maleimidophenoxy) benzene, bis [4- (4-maleimidophenoxy) phenyl] methane, 1,1-bis [4 (3-maleimidophenoxy) phenyl] ethane, 1,1-bis [4- (4-maleimidophenoxy) phenyl] ethane, 1,2-bis [4- (3-maleimidophenoxy) phenyl] ethane, 1,2- And bis [4- (4-maleimidophenoxy) phenyl] ethane.

  Moreover, as a compound containing the at least 2 or more maleimide group used by this invention, following General formula (3)

(Wherein n is an average value of 0 to 10), a compound containing a maleimide group, and the following general formula (4)

(Wherein, p is an average value of 0 to 10), and a compound containing a maleimide group. These maleimide group-containing compounds (A) can be used alone or in combination of two or more. These compounds containing two or more maleimide groups may be used in advance after prepolymerization alone or in combination of two or more, or may be used after prepolymerization with the resin component (C) described later. Also good.

  The content of the compound (A) containing at least two or more maleimide groups is a nitrogen atom in the compound (A) containing maleimide groups with respect to the total mass of the resin components excluding the inorganic components in the resin composition. The content is preferably 2.0% by mass or more and 10% by mass or less, and more preferably 3.0% by mass or more and 7.5% by mass or less.

  If the content of the compound (A) containing at least two or more maleimide groups in the resin composition is within the above range, the substrate obtained from the resulting resin composition, the laminate, etc. have sufficient flame retardancy. Have. Since the nitrogen atom content in the compound (A) containing a maleimide group is about 14% at the maximum, the total amount of other resin components is about 80% by mass at the maximum.

In the circuit board of the present invention, a conductive layer is formed by electroless plating. In addition to (A), (B) aluminum hydroxide, (C) in addition to (A) in the resin composition for forming the insulating layer to be electrolessly plated. It is preferable to contain another resin component, (D) a soluble component for roughening.

(B) Aluminum hydroxide The aluminum hydroxide used in the present invention is not particularly limited as long as it is generally used aluminum hydroxide or hydrated alumina. The chemical formula of these aluminum hydroxides is represented by Al (OH) ₃ or Al ₂ O ₃ .3H ₂ O. Aluminum hydroxide releases crystal water when heated and functions not only as a flame retardant, but also as a soluble component for roughening as described later because it is relatively highly soluble in acid and oxidizer solutions. .

As aluminum hydroxide, the content of Na ₂ O contained as impurities is preferably low. The content of Na ₂ O is preferably less than 0.3%, more preferably 0.2% or less, and still more preferably 0.1% or less. METHOD If Na ₂ O content contained as an impurity in the aluminum hydroxide is large for cleaning, by a method such as is described, for example, in JP-A-8-325011 discloses a Na ₂ O content contained 0. It is preferable to use after reducing to less than 3%.

When the content of Na ₂ O in aluminum hydroxide is within the above range, the resin composition containing aluminum hydroxide is preferable because of its high heat resistance. The reason why the heat resistance is high is that the cured state of the resin composition does not become abnormal because Na released from Na ₂ O in aluminum hydroxide inhibits or rapidly accelerates the curing reaction of the resin composition. This is probably because of this. Furthermore, aluminum hydroxide having a low Na ₂ O content is considered to be one of the reasons that the lowest temperature for releasing crystal water is relatively high, which is high in heat resistance. Moreover, when the content of Na ₂ O in aluminum hydroxide is within the above range, it is preferable that reliability deterioration due to ion migration is unlikely to occur when used as a circuit board. The particle size of aluminum hydroxide used in the present invention is not particularly limited, but those having an average particle size of 0.1 to 10 μm are preferably used. These aluminum hydroxides can be used alone or in combination of two or more.

  Moreover, it is preferable to use a coupling agent for said aluminum hydroxide. As the coupling agent, coupling agents such as silane, titanate, aluminate and zircoaluminate can be used. Among these, a silane coupling agent is preferable, and a silane coupling agent having a reactive functional group is more preferable.

  Examples of silane coupling agents include vinyltrimethoxysilane, vinyltriethoxysilane, N- (2-aminoethyl) 3-aminopropylmethyldimethoxysilane, N- (2-aminoethyl) 3-aminopropyltrimethoxy. Silane, N-phenyl-γ-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-anilinopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, etc., and one or more of these are used. The These silane coupling agents are preferably fixed to the aluminum hydroxide surface by adsorption or reaction in advance. When a coupling agent is used, the adhesiveness between aluminum hydroxide and the resin is improved, and the mechanical strength and heat resistance of the resulting circuit board can be expected to be improved.

  The aluminum hydroxide is desirably contained in an amount of 5 to 100 parts by mass, preferably 5 to 80 parts by mass when the total mass of the resin components is 100 parts by mass. When the content of aluminum hydroxide is within the above range, the flame retardancy effect is obtained, the viscosity when made into a varnish is moderate, and the workability is excellent and the chemical resistance is not adversely affected.

(C) Other resin component In the circuit board of the present invention, a conductive layer is formed by electroless plating, and other resin components in the resin composition for forming an insulating layer to be subjected to electroless plating are particularly limited. Although it does not receive, a well-known thing as a thermosetting resin is used 1 type or in combination of 2 or more types. Specific examples include epoxy resins, phenol resins, cyanate resins, polyimide resins, acrylic resins, and polyphenylene ether resins having reactive functional groups. When an epoxy resin, a phenol resin, or a cyanate resin is used, it is preferable because of good compatibility with the compound (A) when thermosetting.

  The epoxy resin is not particularly limited, but if an epoxy resin containing a large amount of aromatic rings is used, the flame retardancy of the resin composition is improved, and the amount of aluminum hydroxide added as a flame retardant is reduced. The chemical resistance is improved, which is preferable. Epoxy resins containing many aromatic rings include bisphenol A type epoxy, bisphenol F type epoxy, naphthalene type epoxy, cresol novolak type epoxy, bisphenol A novolak type epoxy, phenol aralkyl type epoxy, naphthol aralkyl type epoxy, naphthol novolak type epoxy. Etc. Preferably, cresol novolac type epoxy, naphthol novolac type epoxy, and the like are used.

  The phenolic resin is not particularly limited, but if a phenolic resin containing a large amount of aromatic rings is used, the flame retardancy of the resin composition is improved and the amount of aluminum hydroxide added as a flame retardant is reduced, resulting in resistance to resistance. It is preferable because chemical properties are improved. Examples of the phenol resin containing a large amount of aromatic ring include phenol novolak resin, phenol aralkyl resin, naphthol novolak resin, naphthol aralkyl resin, bisphenol A novolak resin, and the like.

  The cyanate resin is a polyfunctional cyanate ester, a cyanate ester prepolymer, or a mixture thereof, and is not particularly limited. Polyfunctional cyanate esters include 4,4-dicyanatobiphenyl, bis (4-dicyanatophenyl) methane, 2,2-bis (4-cyanatophenyl) propane, bis (4-cyanatophenyl) ether Etc.

  Further, a thermoplastic resin component can be added to these resin components as long as the compatibility with the compound (A) does not deteriorate upon thermosetting. These thermoplastic resin components can impart flexibility or improve electrical characteristics when the resin composition is formed into a sheet. Some of these thermoplastic resin components function as a soluble component for roughening as in the component (D) described later. Specific examples of the thermoplastic component include polyphenylene ether resin, polyimide resin, polybutadiene rubber, acrylonitrile-butadiene rubber, and ethylene acrylic rubber, but are not particularly limited. These thermoplastic resins may be partially modified with an epoxy group, a maleic acid group, an imide group, a carboxyl group, a (meth) acryl group, or the like. The range of the molecular weight of these thermoplastic resins is preferably about 1,000 to 1,000,000. Especially preferably, it is about 1000-10000. When the range of molecular weight is in the above range, the compatibility with the compound (A) is good at the time of thermosetting, which is preferable.

(D) Soluble component for roughening The circuit board of the present invention has a conductive layer formed by electroless plating, and electroless plating was performed in a resin composition forming an insulating layer to be subjected to electroless plating. In order to improve the adhesion strength of the plating, a component for roughening the resin surface can be added. That is, the roughening component is a soluble component having a higher dissolution rate in an acid or oxidizer solution than other resin components. Examples of these soluble components for roughening include organic fillers. The filler has a spherical shape, a crushed shape, a needle shape, a granular shape, and the like, and two or more shapes can be used in combination. The particle size of the filler is about 0.1 μm to 10 μm, preferably about 0.1 μm to 5 μm. When the particle size range of the filler is the above, not only is it easy to uniformly disperse in the resin, but also precipitation and aggregation are less likely to occur when it becomes a varnish used when applying and impregnating the resin composition, Excellent workability. These fillers may be subjected to a surface treatment by a known technique in order to improve dispersibility and adhesion with a resin.

  If it is resin with said shape as an organic filler, there will be no restriction | limiting in particular. As the resin, rubber resins such as polybutadiene rubber, acrylonitrile-butadiene rubber and carboxylated ethylene acrylic rubber, thermosetting resins such as epoxy resin and phenol resin, thermoplastic resins such as polyolefin resin and silicon resin, and the like can be used. Moreover, it may be a multilayer structure (core-shell structure) of two or more kinds of resins. The addition amount of these organic fillers is preferably 1 to 20% by mass, more preferably 1 to 10% by mass with respect to the total mass of the resin components excluding the inorganic components in the resin composition. is there. When the addition amount of aluminum hydroxide (B) is relatively large, a sufficient roughening effect can be obtained even if the addition amount of the organic filler is very small.

(Curing accelerator)
In the circuit board of the present invention, a conductive layer is formed by electroless plating, and the resin composition forming the insulating layer to be subjected to electroless plating preferably contains a curing accelerator. Examples of curing accelerators include imidazoles such as 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-heptadecylimidazole, 2-ethyl-4-methylimidazole tetraphenylborate; triethanolamine, triethylenediamine Amines such as N-methylmorpholine; metal catalyst compounds such as zinc octylate; tetraphenylboron salts such as tetraphenylphosphonium tetraphenylborate and triethylammonium tetraphenylborate; 1,8-diaza-bicyclo (5,4 0) Undecene-7 and its derivatives. These curing accelerators can be used singly or in combination of two or more.

  The content of these curing accelerators is desirably blended so as to obtain the desired gelation time of the varnish or prepreg described later, but generally the resin component excluding the inorganic component in the resin composition. It is preferably used in the range of 0.005 to 10% by mass with respect to the total mass.

(Additive)
In the circuit board of the present invention, a conductive layer is formed by electroless plating, and an additive may be added to the resin composition for forming an insulating layer to be electrolessly plated, depending on the application. Preferable examples of the additive include dyes, pigments, lubricants, anti-settling agents, antifoaming agents, leveling agents, additives commonly used as surface tension adjusting agents, and the like. Specific examples include fluorine-based, silicon-based, and acrylic-based antifoaming agents and leveling agents. In general, the content of the additive is preferably used in the range of 0.0005 to 10 parts by mass with respect to 100 parts by mass of the total amount of the resin components.

(Method for preparing resin composition)
In the circuit board of the present invention, a conductive layer is formed by electroless plating, and a resin composition for forming an insulating layer to be subjected to electroless plating is, for example, a compound (A) containing a maleimide group and another resin component (C ), And the soluble component for roughening (D), preferably at 80 to 200 ° C., for about 0.1 to 10 hours by heating and mixing to obtain a uniform mixture. When adding aluminum hydroxide (B), said mixture can be grind | pulverized at normal temperature, it can also mix in a powder state, and aluminum hydroxide can also be mixed in the resin varnish described below.

(Resin varnish)
For the insulating layer used for the circuit board of the present invention, a resin varnish obtained by dissolving the above resin composition in a solvent can be used in the production. Solvents used in the resin varnish include ethylene glycol monoethyl ether, propylene glycol monomethyl ether, ethylene glycol monobutyl ether, N, N-dimethylformamide, N, N-dimethylacetamide, dioxane, acetone, N-methyl-2-pyrrolidone , Dimethyl sulfoxide, methyl ethyl ketone, methyl isobutyl ketone, cyclohexane, 2-heptanone and the like. As the solvent, those having a relatively low boiling point are preferable, and methyl ethyl ketone, acetone, dioxane or a mixture containing these as a main component is preferably used.

  The resin varnish used in the production of the insulating layer used for the circuit board of the present invention is a resin other than the above (A), (B), (C), and (D) within the range not impairing the object of the present invention. It may contain components. The content of the compound (A) containing a maleimide group in the resin varnish, aluminum hydroxide (B), other resin component (C), and soluble component for roughening (D) is the same as that of the resin composition.

  The resin varnish preferably contains the curing accelerator as described above, and the content is the same as above. Moreover, the resin varnish can contain the additive etc. which the said resin composition may contain. The resin varnish preferably contains the above resin components in a total amount of preferably 50 to 80% by mass, more preferably 55 to 75% by mass.

  The resin varnish is prepared, for example, by heating and mixing the compound (A) containing a maleimide group and another resin component (C) in an organic solvent to obtain a uniform solution, and then aluminum hydroxide (B), The soluble component for roughening can be mixed and adjusted. Although the temperature at the time of heating and mixing depends on the boiling point of the organic solvent, it is preferably 50 to 200 ° C., and the heating and mixing time is preferably 0.1 to 20 hours. When mixing (B) and (D), a roll kneader such as a two-roll or a three-roll may be used at room temperature or under heating, and equipment such as a raking machine, a ball mill, and a shaker may be used. It can carry out by the well-known method to be used.

(Prepreg)
A prepreg that can be used as one of the insulating layers used in the circuit board of the present invention can be produced by impregnating the base material with the resin composition and then drying to remove the solvent. As a base material, all the well-known base materials used for conventional prepregs, such as a glass nonwoven fabric, a glass cloth, a carbon fiber cloth, an organic fiber cloth, paper, can be used. After applying or impregnating the resin varnish to the base material, a prepreg is produced through a drying step, and the coating method, impregnation method and drying method are not particularly limited, and conventionally known methods are used.

  The drying conditions are appropriately determined depending on the boiling point of the solvent to be used, but it is desirable that the amount of the residual solvent in the prepreg is 1% by mass or less. As a specific example, a residence time of about 5 minutes to 10 minutes is preferable in the range of 140 ° C. to 220 ° C., but in the manufacturing process in which the prepreg is continuously dried, the optimum temperature range is the conveyance. This is not the case because it changes depending on the speed.

(Interlayer insulation sheet)
An interlayer insulating sheet that can be used as one of the insulating layers used in the circuit board of the present invention can be produced by applying the resin composition on a release film and then drying to remove the solvent. As the release film, all known films conventionally used as release films can be used. Specifically, a polyethylene terephthalate (PET) film, a polypropylene film, a 4-methylpentene-1 film, a fluororesin film, and the like. After the resin varnish is applied to the release film, a film is produced through a drying process. However, the application method and the drying method are not particularly limited and conventionally known methods are used.

  The drying conditions are appropriately determined depending on the boiling point of the solvent to be used, but it is desirable that the amount of the residual solvent in the prepreg is 1% by mass or less. As a specific example, a residence time of about 5 minutes to 10 minutes is preferable in the range of 140 ° C. to 220 ° C., but in the manufacturing process in which the prepreg is continuously dried, the optimum temperature range is the conveyance. This is not the case because it changes depending on the speed.

  EXAMPLES Hereinafter, although this invention is demonstrated further more concretely based on an Example, this invention is not limited to these Examples.

Examples 1-7
Among the compositions shown in Table 1, the resin component was placed in a mixed solvent of methyl ethyl ketone: N-methyl-2-pyrrolidone in the flask (mixing ratio was methyl ethyl ketone: N-methyl-2-pyrrolidone = 4: 1) at 80 ° C. for 6 hours. It melt | dissolved and the resin varnish was obtained. To the resin varnish thus obtained, aluminum hydroxide, a curing accelerator, a roughening soluble component, and an additive were added and stirred uniformly, impregnated into an IPC type 1078 glass cloth, and dried at 150 ° C. for 8 minutes. Thus, a prepreg having a thickness of about 75 μm was obtained. When these prepregs were measured for the content of halogen ions and phosphate ions by ion chromatography in accordance with the standard JPCA-ES-01 of the Japan Printed Circuit Industry Association, both were 0.09 wt% or less.

(Flame retardancy test)
After-flame times after these prepregs were flame-contacted by the UL94V method were measured, and V-0, V-1, and V-2 were determined.
(Chemical resistance test)
5 sheets of these prepregs and a copper foil were laminated, and the copper foil of the double-sided copper-clad plate obtained by hot pressing was removed and cut into 5 cm squares and weighed. Further, these plate pieces were left in a 4 mol / liter sodium hydroxide solution (70 ° C.) with stirring for 2 hours. After drying at 150 ° C. for 30 minutes, the weight was measured again, and the decrease in weight was divided by the initial weight to obtain a weight reduction rate to be chemical resistance.
(Electroless plating test)
A bismaleimide triazine double-sided copper-clad plate (0.2 mm thick) and a copper foil 12 μm product were subjected to surface roughening with a sulfuric acid / hydrogen peroxide aqueous surface treatment solution (manufactured by MEC). Next, the previously prepared prepreg was laminated, 18 μm copper foil (GTS-STD, manufactured by Furukawa Circuit Foil Co., Ltd.) was placed, and then heated and pressurized in a vacuum press at 200 ° C. and 1.9 MPa for 75 minutes. Thereafter, all the copper foil was removed and 5 μm electroless copper plating was performed. After electroless copper plating, further electrolytic plating was performed to make the thickness of the conductor layer 25 μm. The substrate thus obtained was cut into 5 cm square, pretreated with a pressure cooker under conditions of 121 ° C. 2.1 atm and RH 100% for 6 hours, dipped on a solder layer at 260 ° C., and swelled after 20 seconds. The number of pieces generated was counted.

In the examples, the following raw materials were used.
(A) Compound containing maleimide group; BMI-S (trade name, nitrogen atom content: about 8%, manufactured by Mitsui Chemicals, Inc.)
BMI-MP (trade name, nitrogen atom content: about 10%, manufactured by Mitsui Chemicals, Inc.)
(B) aluminum hydroxide;
Aluminum hydroxide; HS-330 (trade name, average particle diameter; 7 [mu] m, Na ₂ O content; 0.04%, Showa Denko Co., Ltd.)
CL-303 (trade name, center particle size: 2.5 μm, Na ₂ O amount: 0.21%, manufactured by Sumitomo Chemical Co., Ltd.)
(C) Other resin components;
Naphthol aralkyl epoxy resin, ESN-165S (trade name, epoxy equivalent 220, manufactured by Nippon Steel Chemical Co., Ltd.)
Naphthol aralkyl resin, SN485 (trade name, OH equivalent 215, manufactured by Nippon Steel Chemical Co., Ltd.)
Cyanate resin, AROCY B10 (trade name, manufactured by Asahi Ciba Epoxy Co., Ltd.)
(D) soluble component for roughening;
Epoxidized polybutadiene, B-1000 (trade name, manufactured by Nippon Petrochemical Co., Ltd.)
Curing accelerator;
2-Ethyl-4-methylimidazole (2E4MZ (trade name), manufactured by Shikoku Chemicals Co., Ltd.)
Zinc octylate

Comparative Examples 1 and 2
As a comparative example, a commercially available laminated material for circuit boards shown in Table 2 was used. In Comparative Example 1, a prepreg GHPL-830 manufactured by Mitsubishi Gas Chemical Company was used. In Comparative Example 2, prepreg R-1551 manufactured by Matsushita Electric Works, Ltd. was used. About the test item, it carried out similarly to the Example.

  Compared to the examples, since Comparative Example 1 contains a halogen element and Comparative Example 2 contains a phosphorus element, there is a possibility of adversely affecting the environment at the time of combustion. Is hard to say.

  Since flame retardancy can be obtained without containing halogen compounds and phosphorus compounds, circuit board materials used for electronic components, etc. have relatively low environmental impact (does not contain compounds that can adversely affect the environment) ) Can be used. Moreover, since it is excellent in chemical resistance, it is a circuit board using electroless plating, and it becomes possible to make fine wiring and easy impedance control.

Claims (5)

A circuit board comprising an insulating layer and a conductive layer formed by electroless plating on the insulating layer,
The insulating layer is formed from a resin composition containing substantially no halogen element and having a maleimide group, aluminum hydroxide, and an organic filler soluble in an acid / oxidant solution ,
The said resin composition is a circuit board which contains the said aluminum hydroxide 55.6-80 mass% with respect to the sum total of a resin component, and contains the said organic filler 1-11.1 mass% .   The circuit board according to claim 1, wherein the insulating layer to which electroless plating is applied further contains no phosphorus element.   The circuit board according to claim 1, wherein the resin composition contains 2.0% or more of the compound having a maleimide group in terms of nitrogen with respect to the total mass of the resin. Soluble organic filler acid oxidizing agent solution, polybutadiene rubber, acrylonitrile - butadiene rubber, carboxylated ethylene acrylic rubber is at least one polyolefin resin selected from silicone resin, any one of claims 1 to 3 The circuit board according to one item. The particle size of the soluble organic filler acid oxidizer solution is 0.1 m to 10 m, the circuit board according to any one of claims 1-4.