JPH1154936A - Multilayered printed wiring board and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of haloing and the deterioration of the heat resistance of a multilayered printed wiring board, by forming a conductor circuit on an inner-layer substrate carrying a copper foil circuit, the surface of which is treated with a specific triazine thiol compound after being roughened with an etching solution, through a cured resin layer. SOLUTION: A copper foil circuit is treated with a specific triazine thiol compound (X:H or an alkali metal), such as the thiocyanurate expressed by the formula after the circuit is chemically roughened with an etching solution. Then, an insulating resin layer is formed on the surface-treated copper foil circuit by using an epoxy resin, maleimide resin, (metha)acrylic resin, diallyl phthalate resin, or triazene resin. Of these resins, the epoxy resin is particularly preferable, because the resin has the highest adhesive property against copper. Therefore, the reliability of a multilayered wiring board such as the heat resistance, water resistance, and the adhesive property of an inner layer against the copper foil circuit, etc., can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer printed wiring board, and more particularly, to a multilayer printed wiring board using an inner substrate having a copper foil circuit excellent in heat resistance, haloing resistance and water resistance by a novel surface treatment method. The present invention relates to a multilayer printed wiring board and a method for manufacturing the same.

[0002]

2. Description of the Related Art As electronic devices have become smaller and more multifunctional,
Currently, printed wiring boards are moving toward higher densities. For example, thinner conductor circuits, higher multilayers, smaller via holes including interstitial via holes such as through via holes, blind via holes, and buried via holes, and high-density mounting by surface mounting of small chip components. There is. Further, in recent years, new technologies such as a build-up method in which a glass cloth or the like is not included in an insulating layer have been advanced.

Conventionally, both sides of a copper clad laminate having copper foil laminated on both sides via one or more prepregs such as a glass epoxy prepreg are etched to form a copper foil circuit (hereinafter also referred to as a “circuit pattern”) on an inner substrate. ), Blackening treatment, laying up prepreg and copper foil as appropriate, laminating by heating and pressurizing by pressing, and then patterning by drilling, plating, etching, etc. , A multilayer printed wiring board is manufactured. In addition, the present inventors insulate acrylic resin and / or methacrylic resin (hereinafter referred to as “(meth) acrylic resin”) for the purpose of forming blind via holes easily and reducing the weight as described later. A method for manufacturing a multilayer printed wiring board having a resin layer has been invented.

In these methods, in order to enhance the adhesion between the copper foil circuit on the inner layer substrate and the insulating resin layer, the surface of the copper foil circuit is subjected to a copper oxidation treatment called blackening treatment. However, in a process using an acidic treatment solution such as pickling, soft etching, and copper plating, in a place where a circuit subjected to the black treatment such as a through hole comes into contact with the treatment solution, the black treatment portion is dissolved in the acid. The phenomenon that liquid permeates between the insulating resin layer and the copper foil circuit occurs. Such a phenomenon is called a pink ring because the blackening process around the through hole or the through hole melts and looks pink. At the place where the haloing occurs, the adhesiveness between the copper foil circuit and the insulating resin layer is significantly weakened, and the reliability of the circuit is reduced. In multi-layer printed wiring boards with a large number of small-diameter blind via holes for mounting multi-chip module substrates or chip-size packages, the pink rings come close together, and in extreme cases, multiple pink rings However, there is a problem that the blackening process cannot be used because the blackout may occur.

In order to solve the above-mentioned problems, a method has been devised in which a copper foil surface is once subjected to blackening treatment to precipitate needle-like crystals of copper oxide and then reduced to cuprous oxide or pure copper. Used for an inner layer substrate of a multilayer printed wiring board using a glass epoxy prepreg or the like. Such a processing method suppresses the occurrence of haloing, but the needle-like crystals of copper oxide undergo a chemical change during the reduction treatment step, so that the irregularities are reduced, and the anchor effect is not sufficiently exhibited. Adhesive strength was lower than in the treatment, which limited the range of use.

Further, when the copper is reduced and comes into contact with the insulating resin layer as in the above-described processing method, the heat resistance is lower than when the copper surface is oxidized. Such a decrease in heat resistance is caused especially when a resin cured by polymerization of a CＣC unsaturated double bond such as a (meth) acrylic resin having low adhesion to metallic copper is used as the insulating resin layer. It was remarkable.

[0007]

SUMMARY OF THE INVENTION The present invention provides a multilayer printed wiring board which solves the problems of haloing and the problem of reduced heat resistance as described above, and a method of manufacturing the same.

[0008]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and have arrived at the present invention. That is, according to the present invention, a curable insulating resin layer is formed on an inner substrate having a copper foil circuit obtained by chemically roughening with a corrosive liquid and then treating the surface with a triazine thiol compound represented by the chemical formula (1). A multilayer printed wiring board characterized by being formed and cured, and having a conductive circuit formed on the surface via the cured resin layer. Hereinafter, the present invention will be described in detail.

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Conventionally, as a specific example of a method of roughening a copper foil circuit, a physical roughening treatment such as brush polishing and scrub polishing has been used. Although the treatment is simple, the anchor effect is low, and it can be used for the purpose of increasing the adhesion between the copper foil circuit and the solder resist, but the inner layer of the multilayer printed wiring board which requires a high adhesive strength with the insulating resin layer It could not be used for copper foil circuit on board.

On the other hand, in recent years, a method has been developed in which a surface of a copper foil is chemically roughened by treating with a corrosive solution called soft etching or micro etching. This method is also called chemical polishing, and has a feature that deep irregularities can be obtained and an anchor effect is large for the insulating resin layer. Furthermore, compared with the roughening by mechanical polishing, the roughening process can be easily performed even after the circuit pattern is formed, and the roughening process is also performed on the edge of the pattern, so that the insulating resin layer after the formation of the fine pattern is formed. There is an advantage that the adhesiveness is excellent and the copper foil end surface generated after pattern formation can be roughened.

In the case of a method of chemically roughening the copper surface using a corrosive liquid, if the method is performed before forming a circuit pattern, the adhesion between the resist and the copper surface will be reduced when a dry film resist is applied in the next step. Since it becomes worse and it becomes difficult to form a fine pattern, it is preferable to perform the process after forming the circuit pattern.

As the corrosive liquid used in the chemical roughening method, an aqueous solution obtained by mixing sulfuric acid and hydrogen peroxide and a liquid using sodium persulfate are known. In addition, a corrosive liquid containing an organic acid as a main component is also used, and a corrugated liquid can be formed on the surface of the copper foil. An example of the etching solution is disclosed in JP-A-7-292483.
No. 9-411, comprising a cupric complex of an azole, an organic acid and a halogen ion disclosed in
No. 62, a treating agent containing a copper oxidizing agent and a polyamine and / or a polymer compound having a cationic group. Copper foil circuit of the inner layer substrate of the present invention,
It has been chemically roughened by these etchants.
The average step of the unevenness is preferably in the range of 0.5 to 5 μm. When the thickness is less than 0.5 μm, the anchor effect is not sufficiently exhibited, and the heat resistance cannot be improved. When the thickness exceeds 5 μm, the anchor effect is sufficient. Heat resistance may be lowered, which is not preferable. If the washing is sufficiently performed, the effect of improving the heat resistance can be obtained, but it is economically useless.

[0013] The copper foil circuit after the chemical roughening is then treated with a triazine thiol compound represented by the chemical formula (1). The specific name of the compound is s-triazine-2,
4,6-trithiol (also known as thiocyanuric acid) or an alkali metal salt obtained by converting a part or all of the --SH groups present in one molecule of the compound into an alkali metal salt.

These triazine thiol compounds are industrially produced by reacting 2,4,6-trichloro-1,3,5-triazine with sodium hydrosulfide and can be easily obtained.

A method for treating the surface of a copper foil with these triazine thiol compounds will be described below. First, these triazine thiol compounds are once dissolved in a solvent to form a solution, and then this solution is applied to the surface of a copper foil by spraying or the like, or the inner substrate is immersed in the solution and pulled up. In this case, the reaction between the surface of the copper foil and the triazine thiol compound used in the present invention occurs promptly, so that a sufficient effect can be obtained with a dipping time of about several seconds to one minute. Next, in addition to the chemically bonded triazine thiol compound, an extra non-chemically bonded triazine thiol compound remains on the surface of the copper foil.

If the triazine thiol compound is not converted to an alkali metal salt, the surface treatment of the copper foil is completed by drying as it is. When the triazine thiol compound to be used is an alkali metal salt such as a sodium salt, the surface treatment is completed by further immersing the treated surface in dilute sulfuric acid or the like to replace the alkali metal with hydrogen, followed by washing with water and drying. The alkali metal salt is not preferable because insulation reliability cannot be obtained.

When the triazine thiol compound used in the present invention is not in the form of a salt, it is soluble in organic solvents such as THF and cellosolve and is slightly soluble in ketones such as alcohols and acetone. If the surface is covered with a monomolecular layer of these triazine thiol compounds, there is a sufficient effect, so that a solution having a low concentration can be used. Therefore, various kinds of organic solvents can be used in practice. Further, when the triazine compound used is an alkali metal salt, it can be dissolved in water, and there is an advantage that no harmful volatile components are generated and the working environment is not deteriorated.

When an alkali metal salt of a triazine thiol compound is used as an aqueous solution, air bubbles may adhere to the copper foil and a partial surface treatment may not be performed. Although surface treatment is preferable, a surfactant or a water-soluble organic solvent such as alcohol may be added to the treatment liquid in order to improve wettability.

It is sufficient that the concentration of the triazine thiol compound in the treatment liquid is about 0.1 to 1% by weight. Even if the concentration is increased, the effect does not change at all, but since compounds other than the compound chemically bonded to the copper foil surface are removed by washing with water, it is useless to use a treatment solution having a high concentration. Although it can be used even at a low concentration of less than 0.1% by weight, when used repeatedly, the triazine thiol compound is consumed and the effect is reduced, so that there is a drawback that the frequency of liquid exchange is increased.

The surface treatment method for a copper foil according to the present invention is disclosed in Japanese Patent Application Laid-Open Nos.
It is suitable for the surface treatment of a copper foil circuit in the method of manufacturing a printed wiring board disclosed in Japanese Patent Application Laid-Open No. 232563/1994 and Japanese Patent Application Laid-Open No. 6-250771. The production method comprises laminating a copper-clad insulating sheet obtained by applying an uncured acrylic resin composition to a copper foil, onto a glass epoxy inner layer substrate or the like on which a copper foil circuit has been previously formed, and curing the resin composition. (Hereinafter, referred to as a “method of manufacturing a multilayer printed wiring board using a copper-clad insulating sheet”). In the method for manufacturing a multilayer printed wiring board using such a copper-clad insulating sheet, a hole is formed in a predetermined position of an outer copper foil by etching before the resin composition is cured, and the resin composition is chemically dissolved. After curing the resin composition and the resin composition, a hole is similarly formed in a predetermined position of the copper foil of the outer layer, and a blind via hole can be easily formed by a method such as forming a hole with a carbon dioxide gas laser or an excimer laser. It is widely studied as a method for increasing the density of wiring boards.

On the other hand, a printed wiring board manufactured by a build-up method using a resin having a C ＝ C unsaturated double bond such as an epoxy acrylate resin as an insulating layer, which is proposed in Japanese Patent Application Laid-Open No. 8-139457. In this case, when used for the surface treatment of the inner layer copper foil circuit, excellent effects are exhibited. The build-up method is proposed as a method of applying an uncured insulating resin such as a photosensitive resin on the inner copper foil circuit, forming a blind via hole, and then plating to form an outer conductive circuit. It is known as a method for manufacturing a high-density multilayer wiring board, similarly to the method for manufacturing a multilayer printed wiring board using a copper-clad insulating sheet. Many of the functional groups of the photosensitive resin developed for the build-up method substrate are (meth) acryloyl groups, which are C = C unsaturated double bonds, and are built-up by using the copper surface treatment method of the present invention. The improvement of the reliability of the multilayer board by the up method can be expected.

The mercapto group of the triazine thiol compound used in the present invention can chemically bond to copper, and can be an epoxy group of an epoxy resin used as an insulating material for a printed wiring board, a maleimide resin, or (meth) An addition reaction easily occurs to a C ＝ C unsaturated double bond such as an acrylic resin, and a chemical bond can be formed with these resins. Therefore, when the surface treatment method of the present invention is used, the heat resistance of the printed wiring board and the adhesion between the inner layer copper foil circuit and the insulating resin layer thereon are improved, and the reliability of the multilayer printed wiring board is further improved. Not only can it be significantly improved, but it also has excellent effects on the surface treatment of the inner layer circuit of multilayer printed wiring boards using conventional prepregs made of epoxy resin or maleimide resin and the improvement of the adhesion of solder resist. Useful.

In the production of the multilayer printed wiring board according to the present invention, the resin which can be used for the insulating resin layer formed on the copper foil circuit subjected to the surface treatment according to the present invention is epoxy resin, maleimide resin, Any resin used for printed wiring boards, such as (meth) acrylic resin, diallyl phthalate resin, and triazine resin, can be used. Of these, the epoxy resin has a relatively high adhesiveness to copper, so even without performing the surface treatment according to the present invention, it is possible to use only the chemical polishing or the inner layer circuit that has been subjected to the reduction treatment after the blackening treatment. By performing the surface treatment of the present invention, the adhesiveness between the copper foil circuit and the insulating resin layer is further improved.

On the other hand, (meth) acrylic resin, maleimide resin, diallyl phthalate resin and the like have a functional group involved in the curing reaction of a resin having a C ＝ C unsaturated double bond, or a curable resin containing these resins as a main component. The composition is inferior to epoxy resin in adhesion to metallic copper,
The effect of the surface treatment according to the present invention is remarkably exhibited.

In the method for producing a multilayer printed wiring board according to the present invention, when an insulating resin composition having the following composition (hereinafter referred to as “resin composition of the present invention”) is used, heat resistance is improved.
A multilayer printed wiring board having excellent characteristics of excellent resistance to haloing and water resistance, as well as excellent lightness due to no use of glass cloth in the insulating resin layer and excellent in forming blind via holes. That is, (1) a linear polymer containing acrylic acid and / or methacrylic acid (hereinafter referred to as “(meth) acrylic acid”) and (meth) acrylic acid ester as main components, and Component (meta)
A linear polymer in which a compound having a glycidyl group and a C ＝ C unsaturated double bond is added to part or all of a carboxyl group derived from acrylic acid (hereinafter referred to as “first component”), (2) C = A polymerizable compound having an unsaturated double bond (hereinafter referred to as "second component"); (3) a particulate elastic polymer having an average particle size of 5 m or less (hereinafter "third component");
Called. And (4) a polymerization initiator capable of initiating polymerization of the C ＝ C unsaturated double bond by heating or irradiation with an active energy ray (hereinafter referred to as “fourth component”).
And an insulating resin composition comprising: Hereinafter, the present composition will be described in detail. I will tell.

The first component (meta) used in the present invention
A linear polymer containing acrylic acid and a (meth) acrylic acid ester as main components (hereinafter, referred to as “unmodified acrylic polymer”) is methyl acrylate and / or methyl methacrylate (hereinafter, “acrylate and / or methacrylate”). Is referred to as "(meth) acrylate"), ethyl (meth) acrylate, butyl (meth)
(Meth) acrylates such as acrylate, hexyl (meth) acrylate, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, and tetrahydrofurfuryl (meth) acrylate;
(Meth) acrylic acid and an appropriate composition ratio are dissolved in an alcohol solvent such as isopropyl alcohol, ethylene glycol monoethyl ether, and propylene glycol monomethyl ether, and azobisisobutyronitrile,
It is obtained by copolymerizing benzoyl peroxide or the like as an initiator.

The unmodified acrylic polymer can be copolymerized with a vinyl compound such as styrene or acrylonitrile as another component other than (meth) acrylic acid and (meth) acrylic acid ester. When water resistance is required, styrene is preferably copolymerized in a range of 5 to 30% by weight based on all monomers constituting the polymer.

In order to impart alkali solubility to the resin composition of the present invention before curing, the ratio of (meth) acrylic acid to the other components in the unmodified acrylic polymer is determined as the final composition. It is necessary to adjust the acid value in the range of 0.5 to 3.0 meq / g, and as described later, a part of the carboxyl group derived from (meth) acrylic acid which is a constituent component of the unmodified acrylic polymer. Is a glycidyl group and C =
Considering the case where the polymer is used for addition with a compound having a C-unsaturated double bond, (meth) acrylic acid may be 20 to 50% by weight based on all monomers constituting the polymer. preferable.

When alkali solubility is not required for the resin composition of the present invention before curing, it is not necessary to consider the acid value. Therefore, the amount of (meth) acrylic acid is changed to the glycidyl group and C =
What is necessary is just to superpose | polymerize so that it may become more than equivalent with respect to the compound which has a C unsaturated double bond.

The first component of the present invention comprises, in one molecule, a glycidyl group and a C ＝ C compound in a part or all of the carboxyl group derived from (meth) acrylic acid which is a constituent component of the unmodified acrylic polymer. A compound having a saturated double bond is added.

The compound is capable of insolubilizing and insolubilizing the resin composition of the present invention by heating or an active energy ray capable of polymerizing a C ＝ C double bond such as an electron beam or an ultraviolet ray, and having sufficient mechanical properties as a wiring board. It has the effect of imparting physical properties. Specific examples of the compound include glycidyl (meth) acrylate, allyl glycidyl ether, vinylbenzyl glycidyl ether, 4-glycidyloxy-
Glycidyl (meth) acrylate is preferred in view of availability and easy addition reaction to a carboxyl group.

Further, Japanese Patent Application Laid-Open No. Hei 7-2 according to the present inventors' inventions
Other glycidyl compounds, such as the brominated phenyl glycidyl ether disclosed in US Pat. No. 33226, may be used.

The first component is prepared by coating and drying the resin composition of the present invention on a metal foil such as a copper foil. When storing as a copper-clad insulating sheet suitable for a multilayer printed wiring board, the first component is used from the end of the roll. It is an indispensable component to prevent the exudation and winding deviation of the resin, and to prevent the resin from cracking and falling off from the copper foil after coating and drying. It is 10 to 60% of the entire resin composition of the present invention.

Next, the polymerizable compound having a C ＝ C unsaturated double bond as the second component will be described. They are,
A compound having an acryloyl group, a methacryloyl group, an allyl group, a vinyl group, or the like at a terminal. Specifically, a double bond has one methyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl acrylate,
Monofunctional (meth) acrylates such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, and 2-hydroxy-3-phenoxypropyl acrylate; or compounds having a vinyl group such as styrene and acrylonitrile, or allylphenol, eugenol, and the like Compounds having an allyl group, or compounds having a maleimide group such as N-phenylmaleimide, p-hydroxy-N-phenylmaleimide, p-chloro-N-phenylmaleimide, and the like, and those having two double bonds, 1,3-butanediol di (meth) acrylate, diethylene glycol di (meth) acrylate,
Di (meth) acrylates such as polyethylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, bisphenol A type epoxy di (meth) acrylate, urethane (meth) acrylate, or vinyl compounds such as divinylbenzene, or And allyl compounds such as diallyl phthalate and diallyl ether of bisphenol A. When the number of double bonds is three or more, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth)
Acrylate, dipentaerythritol hexa (meth)
Acrylate, phenol novolak type epoxy (meth) acrylate, triallyl isocyanurate and the like can be mentioned.

Among the above compounds, a compound such as polypropylene glycol di (meth) acrylate, which has a long crosslinking point and gives a soft cured product, and urethane (meth) acrylate, which is compatible with the first component, Preferred are polypropylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate or pentaerythritol tri (meth) acrylate. The compounding amount of these compounds is 1 to 100 parts by weight of the first component.
The range of 0 to 200 parts by weight is preferable from the viewpoint of heat resistance.

The third component, the fine particle-like elastic polymer having an average particle diameter of 5 μm or less, is obtained by curing the resin composition of the present invention.
By uniformly dispersing in the cured product, a structure corresponding to an island having a sea-island structure is formed, and the impact resistance is improved. Specifically, MBS resin, acrylic rubber, cross-linked N
BR and the like. Their average particle size is 5 μm or less. If it exceeds 5 μm, the dispersibility of the third component in the resin varnish obtained by dissolving each component other than the third component in a solvent in the resin composition of the present invention becomes poor, and stability cannot be obtained. The amount of the third component is preferably in the range of 5 to 40% by weight based on the total weight of the resin composition of the present invention in order for the resin composition of the present invention to obtain sufficient impact resistance. 40
When the amount is more than 10% by weight, there is no problem in terms of impact resistance. However, when a resin varnish obtained by mixing the resin composition of the present invention with a solvent is produced, the third component is easily separated, and the varnish is easily removed. Is unfavorable because the stability of the resin composition is lowered and coating unevenness and air bubbles are apt to occur when coating and drying the copper foil.

As a method for dispersing the third component in the resin composition of the present invention, the third component is added in advance to a solvent such as methyl ethyl ketone and dispersed by a homomixer or the like, and then the composition of the resin composition of the present invention is prepared. Preferably, the secondary aggregation of the fine particles is loosened by mixing other components, or dispersing the third component, solvent and other components using a homomixer after mixing. Further, as another method, a three-roll, ball mill or the like is also suitable. If used without sufficiently coagulating the secondary coagulation, the third component is separated in the resin varnish, and the storage stability of the varnish is significantly reduced. Even if this varnish is applied to a copper foil, a uniform coating film is obtained. When not heat-laminated copper-clad insulating sheet coated with the resin composition of the present invention on an inner substrate having a copper foil circuit,
Bubbles are more likely to bite and lower insulation reliability. If the agglomerated particles are large, apply a coated copper-clad insulating sheet,
Since the copper foil is deformed while being stored after being stacked or wound, the formation of a fine circuit by the etching method may be significantly impaired.

Among the polymerization initiators as the fourth component, examples of the initiator by heating include an organic peroxide type and an azobis type. Among these, dialkyl peroxides are preferred from the viewpoint of high storage stability due to a high decomposition initiation temperature and low generation of low molecular weight volatile components when decomposed. Specifically, dicumyl peroxide, t -Butylcumyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane and 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne. Further, the amount is preferably 0.5 to 5 parts by weight based on 100 parts by weight of the resin composition of the present invention.
If the amount is less than 0.5 part by weight, the polymerization is insufficient. If the amount exceeds 5 parts by weight, the shelf life is shortened and the amount of the decomposition product of the initiator is increased, so that the heat resistance may be impaired.

Among the polymerization initiators as the fourth component, the initiators caused by ultraviolet rays include aromatic ketones such as benzophenone, Michler's ketone, xanthone and thioxanthone.
2-ethylanthraquinone; acetophenones such as acetophenone, trichloroacetophenone, 2-hydroxy-2-methylpropiophenone, 1-hydroxycyclohexylphenyl ketone, benzoin isopropyl ether, benzoin isobutyl ether, and 2,2-diethoxyacetophenone; diketones And benzyl, methylbenzoyl formate and the like. The compounding amount is preferably 0.5 to 10 parts by weight based on 100 parts by weight of the resin composition of the present invention. In the case where curing by an electron beam among the active energy rays is used, the polymerization initiator is not essential.

The resin composition of the present invention comprises at least the above 4
It is a resin composition containing the components as essential components. In order to impart flame retardancy to the resin composition, a glycidyl ether of a halogenated phenol compound and (meth) acrylic acid are further added as a fifth component. It is preferable to add phosphorus or a phosphorus-based flame retardant as a reactant with and / or as the sixth component.

Specific examples of the reaction product of the glycidyl ether of the halogenated phenol compound, which is the fifth component, with (meth) acrylic acid include a reaction product of tetrabromobisphenol A diglycidyl ether with (meth) acrylic acid.
Examples include a reaction product of a tetrabromobisphenol A skeleton and an epoxy resin (for example, DER514 manufactured by Dow) containing both bromine-free bisphenol A and (meth) acrylic acid. If desired, two or more kinds may be used. it can. Further, compounds having different bromine substitution numbers per bisphenol A skeleton, such as a monobromo compound and a dibromo compound, which are contained as by-products of tetrabromobisphenol A, may be present. Further, a reaction product of a monofunctional brominated epoxy resin (eg, BROC series manufactured by Nippon Kayaku Co., Ltd.) and (meth) acrylic acid or a polyfunctional brominated epoxy resin (eg, BREN series manufactured by Nippon Kayaku Co., Ltd.) And a (meth) acrylic acid reactant can also be used. Among these, a bifunctional compound that can have both strength and appropriate flexibility when used in the present resin composition is preferable, and bromine is particularly preferable as a halogen type because of its excellent flame retardancy. If desired, two or more of these compounds can be added. The amount of the fifth component to be added is 5 to 25 in the resin composition of the present invention.
%.

If the bromine content is less than 5% by weight, the flame retardancy of the cured product of the resin composition of the present invention cannot be sufficiently obtained unless 2% by weight or more of phosphorus derived from the sixth component described below is added. It is not preferable to mix a large amount of phosphorus because the insulating property is reduced. When the amount of bromine is more than 25% by weight, flame retardancy can be obtained, but the halogen compound is liable to be removed during heating, and solder heat resistance and long-term reliability are undesirably reduced.

Specific examples of the sixth component phosphate ester include tricresyl phosphate, tri (2,6-dimethylphenyl) phosphate (PX130 manufactured by Daihachi Chemical Industry Co., Ltd.), and triaryl phosphate (Ajinomoto ( Reophos) available from Co., Ltd. can be used, and if desired, two or more kinds can be added. Red phosphorus, which is a simple substance of phosphorus, also has a high flame-retardant effect, and its fine powder, for example, Hishigard CP manufactured by Nippon Chemical Industry Co., Ltd. can be used.

The compounding amount of the sixth component is preferably such that the phosphorus content in the resin composition of the present invention is in the range of 0.1 to 2% by weight. When the phosphorus content is less than 0.1% by weight, flame retardancy cannot be obtained unless a larger amount of a bromine compound is added, so that a large amount of halide decomposed products are generated during soldering, and heat resistance is reduced. If it is not sufficient, and if it exceeds 2% by weight, electrical insulation tends to deteriorate.

The resin composition of the present invention may further contain an additive such as an inorganic filler such as talc, calcium carbonate or silica, a leveling agent, a defoaming agent, a pigment or an ion scavenger, which is usually used, or a solvent. May be added as needed.

As the solvent for forming the resin varnish,
After dissolving each component other than the components and applying the resin composition of the present invention to the copper foil, those which volatilize by heating and time to such an extent that the resin composition does not polymerize, specifically, methyl ethyl ketone, ethanol and Those having a boiling point of less than 100 ° C., such as isopropyl alcohol, may be mentioned. The solvent is preferably blended so that the solid content of the resin varnish is 30 to 80% by weight.

The resin composition of the present invention is suitable for the method for producing a multilayer printed wiring board using the above-mentioned copper-clad insulating sheet. With this method, the formation of blind via holes for making electrical connection between the inner layer copper foil circuit and the outer layer conductor circuit has conventionally been drilled one by one. If used, the copper foil at a predetermined position is removed by an etching method,
By dissolving and removing the exposed resin composition with an aqueous alkali solution, a large number of blind via holes can be formed at once, and the production efficiency can be further increased. Removal of the exposed resin composition is also possible using an aqueous solution containing an organic solvent such as acetone, ketones such as methyl ethyl ketone and the like, alcohols such as methanol and ethanol, cellosolve and carbitol, or an organic solvent. An alkaline aqueous solution is preferable in that the working environment is maintained.

The dielectric constant of the conventional glass epoxy laminate is 1
It is 4.7-5.0 in MHz. The epoxy resin alone has a dielectric constant of 3.7, but it is known that the dielectric constant increases when glass cloth is used as a reinforcing material. When the resin composition of the present invention is an insulating resin, the dielectric constant is 1 MHz at 1 MHz because of the absence of glass cloth and the characteristics of the resin.
When it is used as an interlayer insulating material, it is advantageous for speeding up signal transmission.

[0049]

The heat resistance of the multilayer printed wiring board having the surface-treated copper foil circuit on the inner layer substrate used in the present invention is remarkably improved. The reason for this is that roughening the glossy surface of the copper foil causes an anchor effect between the copper foil and the insulating resin layer above it, and in addition, the surface of metallic copper that generally has low adhesion to the insulating resin layer Is presumed to be due to a synergistic effect of coating with a compound having high reactivity with the resin.

[0050]

The present invention will be described in detail below with reference to examples. (Synthesis of base polymer) n-butyl acrylate 2
6.8 parts by weight, 5.2 parts by weight of styrene, acrylic acid 2
6.8 parts by weight and 0.2 of azobisisobutyronitrile
The mixture consisting of 5 parts by weight was heated at a temperature of 7 under a nitrogen gas atmosphere.
The mixture was dropped into 100 parts by weight of a mixed solvent of methyl ethyl ketone and ethanol (mixing ratio = 7: 3) maintained at 5 ° C. over 5 hours. Thereafter, the mixture was aged for 0.5 hour, and further 0.3 parts by weight of azobisisobutyronitrile was added, followed by aging for 4 hours to synthesize an unmodified acrylic polymer. Then, while adding 0.23 parts by weight of hydroquinone as a polymerization inhibitor and blowing in a small amount of air, 1.5 parts by weight of N, N-dimethylbenzylamine and 14.7 parts by weight of glycidyl methacrylate were added. After reacting for an hour, the molecular weight is 15,000 to 50,000, and the acid value is 2.25.
A first component having a carboxyl group having a meq / g of 0.9 mol / kg and an unsaturated group content of 0.9 mol / kg (hereinafter referred to as "base polymer") was synthesized.

(Preparation of Resin Composition) 30 parts by weight of the base polymer synthesized as described above in terms of solid content, 10 parts by weight of ethylene oxide-modified bisphenol A diacrylate (Aronix M210 manufactured by Toagosei Co., Ltd.) 40 parts by weight of brominated epoxy methacrylate (bromine content in solid content is about 38%), 7 parts by weight of triarylphosphoric acid (phosphorus content 8%) in terms of solid content, and a thermal polymerization initiator (Nippon Oil & Fats Co., Ltd. ) Perhexin 25B) 2.0 parts by weight were blended and mixed well. Acrylic rubber fine particles previously kneaded with two rolls (DHS manufactured by Nippon Synthetic Rubber Co., Ltd.)
-2, an average particle size of 0.07 μm) is dispersed in methyl ethyl ketone at a solid content concentration of 20% by weight, and 100 parts by weight of the dispersion is added thereto. A resin composition was prepared, and methyl ethyl ketone was added to adjust the viscosity to about 700 cps. Then, the mixture was filtered through a 300th filter cloth, and further filtered under pressure using a filter having a pore size of 5 μm to prepare a resin varnish.

(Example 1) (Surface Treatment of Inner Layer Substrate) An organic acid-based corrosive liquid (MEC etch bond manufactured by MEC Corporation) holding a double-sided copper-clad laminate (ELC4765 manufactured by Sumitomo Bakelite Co., Ltd.) at 40 ° C. C
Z8100) after spraying for 90 seconds, washing with water,
After washing with a 5% by weight sulfuric acid aqueous solution for 10 seconds, it was further washed with water to form irregularities of about 3 μm on the surface. This substrate was prepared in advance at a concentration of 1% by weight of s-triazine-2,4,6-
After immersing in a solution containing trithiol (Disnet F, manufactured by Sankyo Kasei Co., Ltd.) and a mixed solvent of acetone / ethanol (mixing ratio = 1: 1) for 10 seconds, washing with water and drying, it was used as an inner layer substrate for producing a test piece. . Using this inner layer substrate, a test piece was prepared by the method described later and evaluated. The results are shown in Table 1.

Example 2 (Surface Treatment of Inner Layer Substrate) A s-triazine-2,4 prepared in advance in the same manner as in Example 1 at a concentration of 1 wt. Immersion in an aqueous solution of sodium salt of 6,6-trithiol (Disnet TTN manufactured by Sankyo Kasei Co., Ltd.) for 10 seconds, washing with water, immersing in a 5% by weight aqueous sulfuric acid solution for 10 seconds, washing with water, and drying to prepare a test piece It was used as an inner layer substrate. Using this inner layer substrate, a test piece was prepared by the method described later and evaluated. The results are shown in Table 1.

(Comparative Example 1) (Surface Treatment of Inner Layer Substrate) A substrate having a copper foil surface with irregularities formed in the same manner as in Example 1 was directly dried to obtain an inner layer substrate for producing a test piece. Using this inner layer substrate, a test piece was prepared by the method described later and evaluated. The results are shown in Table 1.

(Comparative Example 2) (Surface Treatment of Inner Layer Substrate) A copper foil of a double-sided copper-clad laminate (manufactured by Sumitomo Bakelite Co., Ltd .: ELC4765) was blackened and dried to obtain an inner layer substrate for producing test pieces. . Using this inner layer substrate, a test piece was prepared by the method described later and evaluated. The results are shown in Table 1.

(Comparative Example 3) (Surface Treatment of Inner Layer Substrate) A copper foil of a double-sided copper-clad laminate (manufactured by Sumitomo Bakelite Co., Ltd .: ELC4765) is subjected to a blackening treatment, then subjected to a reduction treatment, dried and dried to form a test piece An inner layer substrate for fabrication was used. Using this inner layer substrate, a test piece was prepared by the method described later and evaluated. The results are shown in Table 1.

(Comparative Example 4) (Surface Treatment of Inner Layer Substrate) A substrate having irregularities formed on the surface of a copper foil in the same manner as in Example 1 was prepared at a concentration of 1% by weight to prepare s-triazine-2-. Dibutylamino-4,6
-Dithiol (Disnet DB, manufactured by Sankyo Kasei Co., Ltd.) was immersed in an acetone solution for 10 seconds, washed with water, and then dried to obtain an inner layer substrate for producing a test piece. Using this inner layer substrate, a test piece was prepared by the method described later and evaluated. The results are shown in Table 1.

(Preparation of Test Piece and Measurement of Physical Properties) For all the surface-treated inner layer substrates of each of the examples and comparative examples, test pieces were prepared by the following methods, and the physical properties were measured.

The above resin composition is applied to the roughened surface of a copper foil having a thickness of 18 μm using a bar coater, dried at 70 ° C. for 10 minutes, and further dried at 110 ° C. for 5 minutes to evaporate the solvent. Then, a resin layer having a thickness of about 80 μm was formed to produce a copper-clad insulating sheet having a two-layer structure composed of a copper foil and a resin. The copper-clad insulating sheet was used before being laminated until a laminating process described later was performed, in which a polyethylene protective film was stuck to the resin surface in order to prevent dust and the like from adhering.

The resin surface of the copper-clad insulating sheet was bonded to the treated surface side of the glass epoxy substrate surface-treated in each of the examples and comparative examples, and bonded using a hot roll laminator.
An electron beam with an accelerating voltage of 175 kV was
After Mrad irradiation, the resin layer was cured by heating at 170 ° C. for 30 minutes to produce a copper-clad laminate panel having an inner substrate.

(Solder Heat Resistance Test) A copper plating layer having a thickness of about 20 μm was formed on the outer copper foil of the above-mentioned panel in which the resin layer was cured, cut into a size of 4 cm square, and 2.5 cm × 2 by an etching method. A test piece for a solder heat resistance test was prepared by forming a copper foil pattern of 0.5 cm at the center. The test piece was floated on a molten solder bath at a bath temperature of 260 ° C. and 280 ° C. with the copper foil side down, and the heat resistance was measured. While floating the test piece, grasp the end of the test piece with tweezers, measure the time until the impact when the copper foil swells is transmitted, and etch the outer layer copper foil to confirm the presence of swelling It was removed and visually confirmed.

(Haloing test) The outer layer copper foil of the above-mentioned panel where the resin layer was cured was removed by etching, and the inner layer copper foil surface-treated through the resin was made visible. Next, a hole having a diameter of 1 mm was formed using a drill to obtain a test piece. After immersing the test piece in 10% hydrochloric acid,
After washing with water and drying, changes in the inner layer copper foil around the drill hole were observed, and the presence or absence of haloing was confirmed.

(Insulation Reliability Test) IPCB specified in IPC standard by etching method on copper foil on inner layer substrate
An A pattern for measuring a surface insulation resistance of a -25 test pattern was formed. This pattern was subjected to the surface treatment described in each of the examples and the comparative examples, to obtain a test inner layer substrate. After bonding the above-mentioned copper-clad insulating sheet to the inner layer substrate so that the terminals for measuring the insulation resistance are exposed, the resin is cured under the same conditions, and finally the outer layer copper foil is removed by an etching method. , And a test piece.

After the initial value of the insulation resistance between the terminals of the test piece was measured in advance, the test piece was applied at 121 ° C. and a relative humidity of 97% while applying a DC voltage of 20 V between the terminals.
The test piece was taken out after being left in a pressure cooker test (PCT) machine for 8 hours, left for 1 hour at 23 ° C. and 60% relative humidity, and then the insulation resistance was measured. The results are shown in Table 1.

[0065]

[Table 1]

[0066]

According to the surface treatment method of the present invention, it is possible to remarkably improve the reliability of the multilayer wiring board, such as heat resistance, water resistance, and adhesion between the inner copper foil circuit and the insulating resin layer. Moreover, even when used as a surface treatment of an inner layer circuit of a multilayer wiring board using a conventional prepreg, excellent effects can be obtained, and it is extremely useful industrially. Furthermore, when the resin composition of the present invention is used, it has a structure without a reinforcing material such as glass cloth, and also has impact resistance, heat resistance, flame retardancy, and insulation reliability that cannot be obtained with a conventional acrylic resin. It is possible to produce a material, and it is suitable for thin and light weight, high-speed transmission, and it is possible to manufacture a multilayer printed wiring board excellent in mass productivity, which is industrially extremely useful.

Claims (4)

[Claims] Claims: 1. A curable insulating resin layer is formed on an inner substrate having a copper foil circuit obtained by chemically roughening with an etchant and treating the surface with a triazinethiol compound represented by the chemical formula (1). A multilayer printed wiring board characterized by being formed and cured, and having a conductive circuit formed on the surface via the cured resin layer. Embedded image 2. The multilayer printed wiring board according to claim 1, wherein the curable insulating resin is cured by polymerization of a CＣC unsaturated double bond. 3. The curable insulating resin is (1) a linear polymer containing acrylic acid and / or methacrylic acid and acrylate and / or methacrylate as main components, and is a constituent component thereof. Acrylic acid and / or
Or a linear polymer in which a compound having a glycidyl group and a C ＝ C unsaturated double bond is added to part or all of a carboxyl group derived from methacrylic acid, (2) a polymer having a C ＝ C unsaturated double bond Compound, (3) average particle size is 5μ
m or less, and a composition comprising (4) a polymerization initiator capable of initiating polymerization of the CＣC unsaturated double bond by heating or irradiation with active energy rays. 1 or 2 multilayer printed wiring board. 4. A step of chemically roughening the surface of the copper foil circuit on the inner layer substrate with an etchant; treating the roughened surface of the copper foil circuit with a triazinethiol compound represented by the chemical formula (1). Laminating the resin side of a copper-clad insulating sheet having an uncured or semi-cured curable insulating resin layer formed on a roughened surface of a copper foil on the copper foil circuit of the inner substrate; Exposing a curable insulating resin layer by forming micro holes in the copper foil by an etching method; removing the exposed curable insulating resin layer under the micro holes to form a blind via hole; Exposing;
Curing the curable insulating resin layer; applying copper plating to the surface of the blind via hole to electrically connect the copper foil circuit on the inner substrate to the outer copper foil; etching the outer copper foil Forming a wiring pattern by using a method for manufacturing a multilayer printed wiring board. Embedded image