JPH10154873A - Multilayered printed wiring board and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a multilayered printed wiring board having such a highly reliable heat cycle characteristic, etc., that no crack is produced toward interlayer resin insulating layers from the boundaries between plate resists and conductor circuits due to heat cycles and a method by which the printed wiring board can be manufactured profitably. SOLUTION: In a multilayered printed wiring in which interlayer resin insulating layers and conductor circuit layers provided in no-resist forming sections are alternately laminated upon another through plate resists, clearances are formed between the facing faces of the plate resists and conductor circuits and roughened layers are formed on the surfaces of the conductor circuits. In a method for manufacturing the multilayered printed wiring board, the plate resists are cured and shrunk by heating the resists after the conductor circuits are formed by electroless plating at the no-resist forming sections where the exposed and cured resists are not formed for providing the clearances between the facing faces of the plate resists and conductor circuits.

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 a method for manufacturing the same, and more particularly, to a method for preventing a crack from being generated from an interface between a plating resist and a conductor circuit toward an interlayer resin insulating layer by a heat cycle. The present invention proposes a multilayer printed wiring board having excellent reliability such as cycle characteristics and a method for advantageously producing the printed wiring board.

[0002]

2. Description of the Related Art In an additive wiring board, an interlayer resin insulating layer (adhesive layer for electroless plating) is formed on a substrate, a plating resist is formed on a portion where a conductor pattern is not formed, and then the plating resist is removed. It is manufactured through a process including a series of processes of forming a conductor circuit by applying electroless plating to a portion.

As the plating resist formed on the additive wiring board, a layer of a resin composition comprising an acrylate of cresol novolak type epoxy resin and an imidazole curing agent, as disclosed in JP-A-6-3179045. Is known.

In such an additive wiring board, the plating resist is composed of a layer of a resin composition, while the conductor circuit is composed of a metal layer. Has a significantly different coefficient of thermal expansion. Conventionally, a plating resist has a smooth side wall surface in contact with a conductor circuit due to a demand for a fine pattern.

[0005]

Therefore, in the case of a printed wiring board in which a plating resist is left as a permanent resist on a substrate, good adhesion is obtained because the side wall surface between the plating resist and the conductor circuit is smooth because it is smooth. However, there is a problem that cracks are generated toward the interlayer resin insulating layer (adhesive layer for electroless plating) by a heat cycle because the thermal expansion coefficients are different from each other.

Further, in the case of a printed wiring board in which a surface of a wiring board having a conductive circuit provided on a portion where a resist is not formed is polished and smoothed via a plating resist, and an interlayer resin insulating layer and a conductive circuit are further formed thereon. In addition, there is a problem that cracks are generated from the interface between the plating resist and the conductor circuit toward the interlayer resin insulating layer due to the heat cycle.
The reason is considered that the conductor circuit is plastically deformed in the polishing direction by polishing, and a protrusion is formed, and stress is concentrated on the protrusion due to a difference in thermal expansion coefficient between the plating resist and the conductor circuit, and cracks are generated from this. (See FIG. 2).

The main object of the present invention is to solve the above-mentioned problems of the prior art and to provide not only excellent heat resistance and electrical characteristics, but also, in particular, an interlayer resin insulation layer from the interface between the plating resist and the conductor circuit by a heat cycle. An object of the present invention is to provide a multilayer printed wiring board which does not generate cracks and has excellent reliability such as heat cycle characteristics. Another object of the present invention is to provide a method by which the above-mentioned multilayer printed wiring board can be advantageously manufactured.

[0008]

Means for Solving the Problems The inventor of the present invention has made intensive studies for realizing the above-mentioned object, and as a result, has completed the invention having the following features as the gist. That is, (1) The multilayer printed wiring board of the present invention is a multilayer printed wiring board in which an interlayer resin insulating layer and a conductor circuit layer provided in a portion where a resist is not formed are alternately laminated on a substrate via a plating resist. Wherein a gap is provided between wall surfaces of the plating resist and the conductor circuit facing each other, and a roughened layer is provided on a surface of the conductor circuit.

Here, in the multilayer printed wiring board according to the present invention, the interlayer resin insulating layer is preferably an adhesive layer for electroless plating, and the surface of the plating resist is in contact with the surface of the conductor circuit. Desirably, it is polished and smoothed so as to be on the same plane.

As a method of manufacturing the above-mentioned multilayer printed wiring board, the present invention provides a method in which an interlayer resin insulating layer and a conductor circuit layer provided in a portion where no resist is formed are alternately laminated on a substrate via a plating resist. In the manufacture of a multilayer printed wiring board comprising: (a) forming at least a photosensitive resin insulating layer on the surface of an interlayer resin insulating layer formed on a substrate; Then, this is exposed and cured in a predetermined pattern, and then developed to form a plating resist, (b) a conductor circuit formed by electroless plating on a portion where no plating resist is formed, and (c) heat curing. By curing and shrinking the plating resist to form a gap between the facing wall surfaces of the plating resist and the conductor circuit, and (d) providing a roughened layer on the surface of the conductor circuit. Features We propose a method for manufacturing a multilayer printed wiring board.

Here, in the method for manufacturing a multilayer printed wiring board according to the present invention, it is preferable that the interlayer resin insulating layer is formed using an adhesive for electroless plating.
The surface of the plating resist is desirably polished and smoothed so as to be flush with the surface of the conductor circuit.

In the method for manufacturing a multilayer printed wiring board according to the present invention, it is preferable to perform a dissolution treatment on the surface of the plating resist or a dissolution treatment on the surface of the conductor circuit after the treatment (c).

In the method for manufacturing a multilayer printed wiring board according to the present invention, it is preferable that the substrate temperature at the time of exposure and curing in the process (a) is adjusted to 100 ° C. or less, and the process (b) It is preferable that the substrate is immersed in warm water after the treatment of (2).

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION A multilayer printed wiring board according to the present invention is provided with a gap between each of opposing wall surfaces of a plating resist and a conductor circuit so that the conductor circuit and the plating resist do not contact each other. The feature is that a roughened layer is provided on the surface of the circuit. On the other hand, the method for manufacturing a multilayer printed wiring board according to the present invention includes a method of forming a conductive circuit by electroless plating on a non-formed portion of the exposed and cured plating resist in order to provide a gap between each of the facing walls of the plating resist and the conductive circuit. Is formed, and then the plating resist is cured and shrunk by heat treatment.

Thus, the conductor circuit is firmly adhered to the interlayer resin insulation layer by the anchor effect of the roughened layer, and the expansion and contraction of the conductor circuit can be suppressed. At the interface between the conductor circuit and the plating resist, the interlayer resin insulation layer ( Cracks do not occur toward the electroless plating adhesive layer).

It is sufficient that the plating resist is present at the time of electroless plating. Even if the plating resist cures and contracts after plating, it does not affect the shape of the conductor pattern at all.

Hereinafter, a method for manufacturing a printed wiring board according to the present invention will be described. (1) First, an inner layer copper pattern is formed on the surface of the core substrate. The formation of a copper pattern on this substrate is performed by etching a copper-clad laminate, or an adhesive layer for electroless plating is formed on a substrate such as a glass epoxy substrate, a polyimide substrate, a ceramic substrate, and a metal substrate, There is a method in which the surface of the adhesive layer is roughened to a roughened surface, and electroless plating is performed thereon. Note that a through hole is formed in the core substrate, and the wiring layer on the front surface and the back surface can be electrically connected through the through hole.

(2) Next, an interlayer resin insulation layer is formed on the substrate on which the inner layer copper pattern has been formed in (1). Especially,
In the present invention, it is desirable to use an adhesive layer for electroless plating as the interlayer resin insulating layer.

The adhesive for electroless plating is obtained by dispersing hardened heat-resistant resin particles soluble in an acid or an oxidizing agent in an uncured heat-resistant resin hardly soluble in an acid or an oxidizing agent. Optimal. This is because by roughening and removing the heat-resistant resin particles soluble in an acid or an oxidizing agent, an octopus-shaped anchor can be formed on the surface and the adhesion to the conductor circuit can be improved.

In the above-mentioned adhesive for electroless plating, as the heat-resistant resin which is hardly soluble in an acid or an oxidizing agent, a photosensitive thermosetting resin or a composite of a photosensitive thermosetting resin and a thermoplastic resin is preferable. . Exposure by photosensitization,
This is because via holes can be easily formed by development. In addition, by forming a composite with a thermoplastic resin, the toughness can be improved, and the peel strength of the conductor circuit can be improved,
This is because the occurrence of cracks in the via holes due to the heat cycle can be prevented. Specifically, epoxy acrylate obtained by reacting an epoxy resin with acrylic acid, methacrylic acid, or the like, or a composite of epoxy acrylate and polyether sulfone is preferable. The epoxy acrylate is preferably one in which 20 to 80% of all epoxy groups have reacted with acrylic acid or methacrylic acid.

In the above-mentioned adhesive for electroless plating, the heat-resistant resin particles include a heat-resistant resin powder having an average particle diameter of 10 μm or less and a heat-resistant resin powder having an average particle diameter of 2 μm or less. Agglomerated particles having a size of 2 to 10 μm, a mixture of a heat-resistant resin powder having an average particle size of 10 μm or less and a heat-resistant resin powder having an average particle size of 2 μm or less, and a heat-resistant resin powder having an average particle size of 2 to 10 μm It is desirable to select from pseudo particles obtained by adhering at least one of a heat-resistant resin powder and an inorganic powder having an average particle diameter of 2 μm or less on the surface. These are because they can form complex anchors. As the resin of the heat-resistant resin particles, epoxy resin, amino resin (melamine resin, urea resin, guanamine resin) and the like are preferable. Particularly, the solubility of an epoxy resin in an acid or an oxidizing agent can be arbitrarily changed by changing the type of the oligomer, the type of the curing agent, and the crosslinking density. For example, a bisphenol A-type epoxy resin oligomer cured with an amine-based curing agent is easily dissolved in an oxidizing agent. However, the novolak epoxy resin oligomer cured with an imidazole-based curing agent is hardly dissolved in the oxidizing agent.

In the present invention, the interlayer resin insulating layer does not need to be a single layer. For example, first, an uncured resin insulating material is applied, dried, and then further adhered for electroless plating. An agent can be applied to form a two-layer resin insulating layer. The lower layer has an average particle size of 0.1 to 0.3 μm.
m or less, and the upper layer contains a mixture of a heat-resistant resin powder having an average particle diameter of 10 μm or less and a heat-resistant resin powder having an average particle diameter of 2 μm or less. It is also possible to use a resin insulating layer having a two-layer structure as an adhesive layer for electroless plating.

(3) After drying the interlayer resin insulation layer formed in (2) above, in the case of a photosensitive resin, it is exposed and developed and then thermally cured, and in the case of a thermosetting resin, ,
After thermosetting, laser processing is performed to provide an opening for a via hole in the interlayer resin insulating layer.

(4) After roughening the surface of the interlayer resin insulating layer provided with the opening for via hole in (3) with an acid or an oxidizing agent, a catalyst nucleus is provided. Here, examples of the acid that can be used for the above-mentioned roughening treatment include phosphoric acid, hydrochloric acid, sulfuric acid, and organic acids such as formic acid and acetic acid, and organic acids are particularly desirable. This is because when the roughening treatment is performed, the metal conductor layer exposed from the via hole is hardly corroded. On the other hand, as the oxidizing agent, chromic acid and permanganate (such as potassium permanganate) are desirable. In particular, in the case of dissolving and removing the amino resin, it is preferable to perform a roughening treatment alternately with an acid and an oxidizing agent. In addition, it is desirable to use a noble metal ion or a noble metal colloid for providing the catalyst nucleus. Generally, palladium chloride or a palladium colloid is used.
Note that it is desirable to perform a heat treatment to fix the catalyst core. Palladium is preferred as such a catalyst core.

(5) A solution of the plating resist composition is applied to the surface of the substrate to which the catalyst nucleus has been applied in (4), and dried to form a resin layer. After exposure and curing to the pattern described above, development processing is performed to form a plating resist. In particular, in the present invention, curing by heat treatment is not performed at this stage. For example, in the above exposure and development processing, exposure is performed at 600 mJ / cm ² ,
Next, development is carried out using a developer comprising a glycol ether solvent such as DMTG and water and water, followed by heating and drying at 30 ° C. for 3 minutes.

Here, in the present invention, it is desirable that the substrate temperature during the above-mentioned exposure and curing be adjusted to 100 ° C. or less. If the substrate temperature exceeds 100 ° C during exposure curing, thermal curing proceeds during exposure curing of the plating resist, and after forming an electroless plating film, the plating resist does not shrink due to thermal curing even when heated, and the plating resist and conductor This is because a gap with the circuit cannot be provided.

As the plating resist composition, for example, a composition comprising a photosensitive resin such as epoxy acrylate obtained by reacting an epoxy resin with acrylic acid or methacrylic acid and an imidazole curing agent, or a photosensitive resin such as epoxy acrylate is used. A composition comprising a thermoplastic resin such as polyether sulfone and an imidazole curing agent can be exemplified, and other commercially available products can also be used.

Here, as the epoxy resin which is the basic skeleton resin of the epoxy acrylate, a novolak type epoxy resin is desirable. Novolak type epoxy resin
Has a rigid skeleton, high crosslinking density, and high water absorption of the cured product
This is because it can be adjusted to 0.1% or less and has excellent base resistance.
Novolak type epoxy resins include cresol novolak type and phenol novolak type.

Epoxy acrylate is used for all epoxy groups.
It is desirable that 20 to 80% react with acrylic acid or methacrylic acid. If the acrylate ratio is too high, the hydrophilicity due to the OH group increases and the hygroscopicity increases, and if the acrylate ratio is too low, the resolution decreases. The ratio of the epoxy acrylate to the polyether sulfone is desirably about 50/50 to 80/20. If the amount of epoxy acrylate is too large, the flexibility decreases, and if it is too small, photosensitivity, base resistance, acid resistance,
This is because the antioxidant properties decrease.

The imidazole curing agent is used as a curing agent for the photosensitive resin, which is a resin component of the plating resist composition, because the epoxy resin cured with the imidazole curing agent has excellent heat resistance and chemical resistance, and has a high resistance to bases. This is because the properties are excellent.

This imidazole curing agent is desirably liquid at 25 ° C. This is because uniform kneading is difficult with powder, and liquid can be kneaded more uniformly. Examples of such a liquid imidazole curing agent include 1-benzyl-2-methylimidazole (product name: 1B2MZ), 1-cyanoethyl-2-ethyl
-4-methylimidazole (product name: 2E4MZ-CN), 4-methyl
2-ethylimidazole (product name: 2E4MZ). The addition amount of the imidazole curing agent is desirably 1 to 10% by weight. The reason for this is that if the added amount is within this range, uniform mixing is easy.

Such a plating resist composition further includes benzophenone as an initiator, Michler's ketone as a sensitizer, a thermosetting resin for improving heat resistance and base resistance, and imparting flexibility. To improve the resolution, a photosensitive monomer and an acrylate polymer as a leveling agent can be added and mixed.

Benzophenone as an initiator (photopolymerization initiator) and Michler's ketone as a sensitizer (photopolymerization auxiliary) are
It is desirable to dissolve them in a heated glycol ether-based solvent at the same time and to dissolve them in the plating resist composition. This is because the use of only Michler's ketone has low solubility in the above-mentioned solvent, causes a dissolved residue even when heated, and precipitates at room temperature. The reason why benzophenone and Michler's ketone are completely dissolved when mixed simultaneously in the above-mentioned solvent is unknown, but benzophenone and Michler's ketone have a structure similar to a complex in a solvent, and by forming a structure similar to this complex in Michler's ketone, It is presumed that the solubility of is increased. According to such a method, since benzophenone and Michler's ketone are completely dissolved in the glycol ether-based solvent, the plating resist composition in which the benzophenone and the Michler's ketone are compatible becomes a uniform phase. As a result, the unexposed portions of the layer of the plating resist composition can be completely removed by exposure and development.

The glycol ether solvent for dissolving benzophenone and Michler's ketone is preferably diethylene glycol dimethyl ether (DMDG) and / or triethylene glycol dimethyl ether (DMTG). This is because these solvents can completely dissolve benzophenone and Michler's ketone by heating at about 30 to 50 ° C.

The thermosetting resin as an additional component is preferably a bisphenol type epoxy resin. This is because a bisphenol-type epoxy resin can improve base resistance. The bisphenol type epoxy resin includes a bisphenol A type epoxy resin and a bisphenol F type epoxy resin, and the former is better when the basic resistance is important, and the latter is better when the applicability is important.

The acrylate polymer as an additional component can make the whole plating resist composition uniform. In this case, the kneading performed to obtain a liquid resist as in the related art becomes unnecessary. According to such an acrylate polymer, there is no need to disperse an antifoaming agent in the resist composition, so that the resist surface can be smoothened without developing residue. Here, the acrylate polymer is a polymer obtained by polymerizing one or more esters of an ester of acrylic acid or methacrylic acid with an alcohol having a molecular weight of 500 to 5,000.

(6) Primary plating is applied to the portion where the plating resist has not been formed in the process (5). At this time, not only a copper pattern but also a via hole is formed. The primary plating is desirably an alloy plating using at least two or more metal ions selected from copper, nickel, cobalt and phosphorus. This is because these alloys have high strength and can improve the peel strength. In the electroless plating solution for the primary plating, it is necessary to use at least two kinds of metal ions selected from copper, nickel and cobalt. The reason for this is that these alloys have high strength and peel strength. This is because it can be improved.

In the above electroless plating solution for the primary plating, it is desirable to use hydroxycarboxylic acid as a complexing agent for forming a stable complex with copper, nickel and cobalt ions under basic conditions. In the electroless plating solution for the primary plating, a reducing agent for reducing metal ions to a metal element is selected from aldehyde, hypophosphite (referred to as phosphinate), borohydride, and hydrazine. Desirably, at least one kind is used. This is because these reducing agents are water-soluble and have excellent reducing power. In particular, hypophosphite is desirable in terms of depositing nickel. In the electroless plating solution for the primary plating, at least one basic compound selected from sodium hydroxide, potassium hydroxide, and calcium hydroxide may be used as a pH adjuster for adjusting under basic conditions. desirable. This is because under basic conditions, hydroxycarboxylic acid forms a complex with nickel ions and the like. As the hydroxycarboxylic acid, citric acid, malic acid, tartaric acid and the like are desirable. This is because these easily form a complex with nickel, cobalt, and copper.
The concentration of the hydroxycarboxylic acid is preferably 0.1 to 0.8M. The reason for this is that if it is less than 0.1 M, a sufficient complex cannot be formed, resulting in abnormal precipitation and decomposition of the liquid. On the other hand, if it exceeds 0.8 M, problems such as a low deposition rate and an increase in generation of hydrogen occur. The electroless plating solution for the primary plating desirably contains bipyridyl. The reason for this is that bipyridyl can suppress the generation of metal oxides in the plating bath and the generation of nodules. Note that copper ions, nickel ions, and cobalt ions are supplied by dissolving a compound of copper, nickel, and cobalt such as copper sulfate, nickel sulfate, cobalt sulfate, copper chloride, nickel chloride, and cobalt chloride.

The primary plating film formed by such an electroless plating solution has excellent followability to the roughened surface of the adhesive layer for electroless plating, and traces the form of the roughened surface as it is. Therefore, the primary plating film has an anchor like the roughened surface. Therefore, the adhesion of the secondary plating film formed on the primary plating film is secured by the anchor. Therefore, in order to control the peel strength, the primary plating film is desirably a plating film having a high strength to be deposited by the electroless plating solution as described above, while the secondary plating film has a high electric conductivity and a high deposition rate. Therefore, a plating film deposited with a simple copper plating solution is more desirable than composite plating.

(7) Secondary plating is performed on the primary plating film formed in (6) to form a conductor circuit including a via hole composed of the primary plating film and the secondary plating film. The plating film formed by the secondary plating is preferably a copper plating film. The electroless plating solution for the above-mentioned secondary plating has a copper ion concentration of 0.005 in an electroless plating solution comprising copper ions, trialkanolamine, a reducing agent and a pH adjuster.
~ 0.015mol / l, concentration of pH adjuster is 0.25 ~ 0.35mol
/ L, and it is preferable to use an electroless plating solution having a reducing agent concentration of 0.01 to 0.04 mol / l. This is because the plating solution has a stable bath and generates little nodules and the like. In the above electroless plating solution for secondary plating,
Desirably, the concentration of trialkanolamine is 0.1-0.8M. This is because the plating precipitation reaction most easily proceeds in this range. The trialkanolamine is desirably at least one selected from triethanolamine, triisopanolamine, trimethanolamine, and tripropanolamine. Because it is water-soluble. In the above electroless plating solution for secondary plating, the reducing agent is desirably at least one selected from aldehyde, hypophosphite, borohydride, and hydrazine. This is because it is water-soluble and has a reducing power under basic conditions. The pH adjuster is desirably at least one selected from sodium hydroxide, potassium hydroxide, and calcium hydroxide.

Here, in the present invention, the formation of the conductor circuit by the above-described electroless plating is desirably performed after the substrate on which the plating resist is formed is immersed in warm water. At this time, since the plating resist formed on the substrate swells due to the immersion in the warm water, the following is performed after the electroless plating.
(8) The amount of dehydration and shrinkage due to the heat treatment increases, and the gap generated between the plating resist and the conductor circuit can be further increased. Thereby, the flow of the electroless plating solution or the etching solution used for the roughening treatment of the conductor surface is improved, and the side surface of the conductor circuit is easily roughened.

(8) In particular, according to the present invention, the substrate in which the conductor circuit including the via hole composed of the primary plating film and the secondary plating film is formed on the portion where the plating resist is not formed in the above (6) and (7), 1 to 200 ° C, preferably 150 to 180 ° C.
Heat treatment for up to 5 hours (optimal 3 hours) requires shrinkage of the plating resist due to curing, and it is necessary to form a gap between each of the facing wall surfaces of the plating resist and the conductor circuit.

Here, in the present invention, after the treatment described in the above (8) is completed, by performing a dissolution treatment on the surface of the plating resist, it is possible to further increase the gap generated between the conductor circuit and the plating resist. desirable. The reason for this is that by increasing the gap, the electroless plating solution or the etching solution used for the roughening treatment of the conductor surface becomes more circulating, and the side surface of the conductor circuit is easily roughened. At this time, the dissolution treatment is desirably a chemical treatment using an oxidizing agent such as chromic acid or permanganic acid, or an acid such as formic acid, acetic acid, sulfuric acid, or hydrochloric acid.

Further, in the present invention, it is desirable to further increase the gap generated between the conductor circuit and the plating resist by performing the dissolution treatment on the surface of the conductor circuit after completing the process described in (8) above. . The reason for this is that by increasing the gap, the electroless plating solution or the etching solution used for the roughening treatment of the conductor surface becomes more circulating, and the side surface of the conductor circuit is easily roughened. At this time, the dissolving treatment includes an oxidizing agent such as chromic acid and permanganic acid, an acid such as formic acid, acetic acid, sulfuric acid, and hydrochloric acid, a mixture of sulfuric acid and hydrogen peroxide, ammonium persulfate, sodium persulfate, and potassium persulfate. Persulfate aqueous solution, ferric chloride aqueous solution, cupric chloride aqueous solution,
A chemical conversion treatment using an alkaline aqueous solution containing a copper ammonium complex ion is desirable.

In the present invention, the size of the gap generated between the conductor circuit and the plating resist is 0.1 to 1
Desirably, it is 0 μm. This is because if the size of the gap is within this range, the liquid flow is good and relatively little stress is generated on the adhesive layer for electroless plating due to shrinkage of the plating resist.

(9) Further, in the present invention, a roughening layer is formed on the surface of the conductor circuit by subjecting the conductor circuit to blackening reduction treatment or needle-like plating made of Cu-Ni-P. It is necessary. In particular, since the needle-shaped plating layer made of Cu-Ni-P has conductivity, it does not need to be removed even when forming a via hole and can be advantageously used. Such a roughened layer has a thickness of 0.5 to 5 μm.
It is desirable that If it is too thick, the roughened layer itself will be damaged,
This is because the film is easily peeled off, and if it is too thin, the adhesion is reduced.

Here, in the above-mentioned blackening reduction treatment, a mixed solution of NaOH, NaClO ₂ and Na ₃ PO ₄ is used as a blackening bath, and a mixed solution of NaOH and NaBH ₄ is used as a reducing bath. it can. Specifically, NaOH (1) is used as an oxidation bath (blackening bath).
0 g / l), NaClO ₂ (40 g / l) and Na ₃
PO ₄ (6 g / l) mixed solution, NaOH as a reducing bath
(10 g / l) and a mixture of NaBH ₄ (5 g / l) can be used.

On the other hand, in the needle plating made of Cu-Ni-P, an electroless plating solution containing copper sulfate, nickel sulfate, citric acid, sodium hypophosphite, boric acid, and a surfactant can be used. As for the composition of the electroless plating solution, the copper ion concentration, the nickel ion concentration, and the hypophosphite ion concentration were 2.2 × 10 ^{−2 to} 4.1 × 10 ⁻² mol / mol, respectively.
1, 2.2 × 10 ^{−3 to} 4.1 × 10 ⁻³ mol / l,
Desirably, it is 20 to 0.25 mol / l. This is because the plating film deposited in this range has an excellent anchor effect because the crystal structure becomes a needle-like structure. Also,
EBARA Eugerite Co., Ltd. product name "Interplate"
Plating solution can be used. The composition of the alloy layer obtained by using such an electroless plating solution is 90 to 96 wt%, 1 to 5 wt%,
Desirably, it is 0.5 to 2% by weight. This is because the alloy layer has a needle-like structure at these composition ratios.

Further, as described in JP-A-7-292483, imidazole, 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-
Methylimidazole, 2-phenylimidazole, 2-
Undecyl imidazole, cupric complexes of azoles such as benzimidazole and saturated fatty acids (formic acid, propionic acid, butyric acid, valeric acid), unsaturated fatty acids (acrylic acid), aliphatic saturated dicarboxylic acids (oxalic acid, malonic acid,
Etching solution consisting of organic acids such as succinic acid) and oxycarboxylic acid (glycolic acid, citric acid), or etching consisting of cupric complexes of azoles, organic acids and halogen ions such as fluorine ion, chloride ion and bromine ion Using the liquid, a roughened layer can be formed on the surface of the conductor circuit. By spraying these etching solutions on the surface of the wiring board, the copper of the conductor is oxidized by the cupric complex of azoles, and the organic acid dissolves the copper oxide and the etching proceeds. Also, "Electronic materials 19
An etching solution having a trade name of "MEC etch Bond" manufactured by MEC Corporation is disclosed from page 26 to page 30 of the October 1995 issue, and such a commercially available product can also be used.

It is desirable that the above-mentioned roughened layer typified by needle-shaped plating made of Cu-Ni-P is surface-coated with a metal or a noble metal whose ionization tendency is larger than copper and smaller than titanium. The thickness of the coating metal layer is 0.1 to 2
μm is desirable. In particular, tin is preferable because it can be subjected to displacement plating, does not destroy the needle-like shape, and can suppress local battery reaction to prevent dissolution of the needle-like plating layer.
This substitution reaction with tin is desirably performed using a mixed solution composed of tin borofluoride and thiourea.

Here, the metals having an ionization tendency higher than copper and lower than titanium include titanium, aluminum, zinc,
There is at least one selected from iron, indium, thallium, cobalt, nickel, tin, lead, and bismuth. Noble metals include gold, silver, platinum and palladium. Of these metals, tin is particularly preferred. Tin is advantageous because it can form a thin layer by electroless displacement plating and can follow the roughened layer. Specifically, tin borofluoride 0.1 mol / l, thiourea 1.0 mol / l, temperature 5
An electroless displacement plating solution under the conditions of 0 ° C. and pH = 1.2 can be employed.

(10) Further, if necessary, the surface of the plating resist and the surface of the conductive circuit including via holes are polished so as to be flush with each other, and the processing of (2) to (8) or (9) is performed. By repeating, a desired multilayer printed wiring board is obtained. The surface layer of the multilayer printed wiring board thus obtained is provided in a state where the surface of the interlayer resin insulating layer is roughened, a plating resist is formed on the roughened surface, and the conductor circuit is exposed on the non-formed surface of the plating resist. It has a structure. Therefore, the exposed conductor circuit is protected by covering with a solder resist having an opening in a portion where a solder layer is to be formed.

(11) Then, nickel-gold plating is applied to a portion (pad portion) of the solder resist opening where the solder layer is to be formed, and the solder layer is formed on this portion by a solder transfer method or a screen printing method. Form. In addition,
The solder transfer method is a method in which a solder pattern is formed on a film, and the solder pattern is transferred to the pad by heating and reflowing while the solder pattern is in contact with the pad. Note that the solder layer may be a solder bump.

[0054]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments. Example 1 (1) 18 μm on both sides of a substrate 1 made of glass epoxy resin or BT (bismaleimide triazine) resin having a thickness of 1 mm.
A copper-clad laminate obtained by laminating m copper foils 9 was used as a starting material (see FIG. 1 (a)). By etching the copper foil 9 of the copper-clad laminate in a pattern according to a conventional method, the inner layer copper pattern 2 was formed on both surfaces of the substrate 1 (see FIG. 1B).

(2) The substrate on which the inner layer copper pattern 2 has been formed in the above (1) is washed with water and dried, and then the substrate is acid-degreased and soft-etched. Then, the substrate is treated with a catalyst solution comprising palladium chloride and an organic acid. After treatment to give a Pd catalyst and activate this catalyst, plating is carried out in an electroless plating bath, and Cu-Ni-P
An uneven layer (roughened surface) having a thickness of 2.5 μm of the alloy was formed. Further, the substrate was washed with water and immersed in an electroless tin plating bath composed of a tin borofluoride-thiourea solution at 50 ° C. for 1 hour, and a 0.3 μm-thick surface was formed on the roughened surface of the Cu-Ni-P alloy.
m of tin-substituted plating layers were formed (note that the above-mentioned uneven layer and tin-substituted plating layers are omitted in FIG. 1).

(3) Cresol novolak epoxy resin
After mixing 70 parts by weight of a 25% acrylate (manufactured by Nippon Kayaku), 25 parts by weight of polyether sulfone (manufactured by Mitsui Toatsu), 4 parts by weight of benzophenone, 0.4 part by weight of Michler's ketone and an imidazole-based curing agent, N-methylpyrrolidone is mixed. (NM
While adding P), the viscosity is 30 Pa · s with a homodisper stirrer.
And kneaded with three rolls to obtain an interlayer insulating agent.

(4) 70% by weight of a 25% acrylate of cresol novolac type epoxy resin (manufactured by Nippon Kayaku, molecular weight 2500) dissolved in DMDG (diethylene glycol dimethyl ether), 30 parts by weight of polyether sulfone (PES), imidazole curing (Shikoku Chemicals, trade name: 2E4M
4 parts by weight of Z-CN), 10 parts by weight of caprolactone-modified tris (acroxyethyl) isocyanurate (trade name: Alonix M325, manufactured by Toagosei Co., Ltd.) as a photosensitive monomer, and benzophenone (manufactured by Kanto Chemical) 5 as a photoinitiator Parts by weight, Michler's ketone as a photosensitizer (Kanto Chemical)
5 parts by weight, 35 parts by weight of an epoxy resin particle having an average particle size of 5.5 μm,
After mixing 5 parts by weight of m, the mixture was mixed while adding normal methylpyrrolidone (NMP), the viscosity was adjusted to 2000 cps with a homodisper stirrer, and then kneaded with three rolls to obtain a photosensitive adhesive solution. Obtained.

(5) The interlayer insulating agent obtained in the above (3) is
Using a roll coater, both surfaces of the substrate after the treatment of (2) were applied, left in a horizontal state for 20 minutes, and then dried (prebaked) at 60 ° C. to form an insulating layer 3. Further, the photosensitive adhesive solution obtained in the above (4) is applied on the insulating layer 3 by using a roll coater, left in a horizontal state for 20 minutes, and then dried (prebaked) at 60 ° C. Then, an adhesive layer 4 was formed (see FIG. 1 (c)).

(6) A photomask film on which via holes are drawn is placed on both sides of the substrate on which the interlayer resin insulating layer composed of the insulating layer 3 and the adhesive layer 4 is formed in the above (5). Irradiate and expose. (7) The exposed substrate was spray-developed with triethylene glycol dimethyl ether (DMTG) to form an opening as a 100 μmφ via hole in the interlayer resin insulating layer. Furthermore, the substrate is 3,000 mJ
/ Cm ² , and heat treatment at 100 ° C. for 1 hour and then at 150 ° C. for 5 hours to obtain a 50 μm-thick film having an opening (via hole forming opening 5) with excellent dimensional accuracy equivalent to a photomask film. Interlayer resin insulation layer (two-layer structure)
Was formed. Note that the tin plating layer is partially exposed in the opening serving as the via hole.

(8) The substrate having the via hole forming openings 5 formed in the above (6) and (7) is immersed in chromic acid for 2 minutes, and then the epoxy resin particles in the interlayer resin insulating layer are dissolved. ,
The surface of the interlayer resin insulation layer was roughened, and then immersed in a neutralizing solution (manufactured by Shipley) and washed with water (FIG. 1 (d)).
reference).

(9) By applying a palladium catalyst (manufactured by Atotech) to the substrate subjected to the surface roughening treatment in the above (8), a catalyst nucleus is formed on the surface of the interlayer resin insulating layer and the opening of the via hole. Was.

(10) 46.67 g of a photosensitizing oligomer (molecular weight: 4000) obtained by acrylizing 50% of an epoxy group of a cresol novolak type epoxy resin (manufactured by Nippon Kayaku) in 60 parts by weight of DMDG dissolved in methyl ethyl ketone. 15.0 g of 80 parts by weight of dissolved bisphenol A type epoxy resin (manufactured by Yuka Shell, Epicoat 1001), 1.6 g of imidazole hardener (manufactured by Shikoku Chemicals, trade name: 2E4MZ-CN), polyvalent acrylic as a photosensitive monomer A monomer (Nippon Kayaku Co., Ltd., trade name: R604) (3.0 g) and a polyvalent acrylic monomer (Kyoeisha Chemical, trade name: DPE6A) 1.5 g were mixed, and 0.5 part by weight based on the total weight of these mixtures. 0.36 g of acrylate polymer consisting of 2-ethylhexyl acrylate, butyl acrylate, ethyl acrylate and hydroxy acrylate was dissolved in NMP. 30% polyethersulfone obtained by (PES) to prepare a mixed liquid A was stirred with 12g mixed. On the other hand, a mixed solution B was prepared by dissolving 2 g of benzophenone as a photoinitiator (manufactured by Kanto Kagaku) and 0.2 g of Michler's ketone as a photosensitizer (manufactured by Kanto Kagaku) in 3 g of DMDG heated to 40 ° C. .
The liquid mixture A and the liquid mixture B were mixed and stirred to obtain a liquid resist composition.

(11) The liquid resist composition is applied on both sides of the substrate, which has been subjected to the treatment for providing catalyst nuclei in the above (9), using a roll coater, dried at 70 ° C. for 60 minutes, and dried with PES. The epoxy acrylate was phase-separated to form a 30 μm thick resin layer.

(12) A mask on which a pattern was drawn was laminated on the resin layer formed in the above (11), and the film was exposed to ultraviolet light under the conditions of 1000 mJ / cm ² and cured by exposure.

(13) The resin layer exposed and cured in the step (12) is
Dissolve and develop with a developing solution composed of TG + water to form a plating resist on the substrate where the conductor circuit pattern portion has been removed.
It was exposed and cured with an ultrahigh pressure mercury lamp at 6000 mJ / cm ² .

(14) A pre-plating treatment (specifically, a sulfuric acid treatment or the like and activation of catalyst nuclei) is performed on the substrate after the treatment of the above (13) in advance, and thereafter, an electroless copper plating bath (primary plating) is performed. Electroless plating by plating bath, secondary plating bath)
Electroless copper plating having a thickness of about 15 μm was deposited on the non-resist-formed portions to form outer layer copper patterns 7 and via holes 8, thereby forming a conductor layer by an additive method (see FIG. 1 (e)).

(15) The substrate on which the conductor layer has been formed in the above (14) is subjected to a heat treatment at 100 ° C. for 1 hour and further at 150 ° C. for 3 hours to remove the permanent resist 6 on the interlayer resin insulation layer. , X
A gap was formed between the permanent resist 6 and each of the facing walls of the conductor circuits 7 and 8 by curing and shrinking by 3 μm in the −Y direction and 2 to 3 μm in the Z direction.

(16) Further, in this embodiment, NaOH (10 g / l), NaClO ₂ (40 g / l), Na
Using a mixed solution of ₃ PO ₄ (6 g / l), the surface of the copper conductor circuit is oxidized to provide a roughened layer 10, and then NaOH is used as a reducing bath.
Using a mixture of NaBH ₄ and was reduced and the surface (Fig. 1
(f)).

(17) By repeating the above-mentioned steps (5) to (15), further conductive layers were formed by the additive method. By building up the wiring layers in this way, a six-layer multilayer printed wiring board was formed (see FIG. 1 (g)).

(Embodiment 2) In the step (16) in Embodiment 1, in order to form a roughened layer on the surface of a conductor circuit,
First, a copper sulfate (0.05 m
ol / l), nickel sulfate (0.0039 mol / l), citric acid (0.078 mol / l), sodium hypophosphite (0.33 mol / l)
l), boric acid (0.5 mol / l), surfactant (0.1 g /
1) A plating process is performed using an electroless plating solution (pH = 9), a needle-like plating layer made of Cu-Ni-P is formed on the surface of the conductor circuit, and then tin borofluoride (0.1 mol /
l), using a displacement plating solution (temperature: 50 ° C) consisting of thiourea (1.0 mol / l), a thickness of 3 µm consisting of Cu-Ni-P
A six-layer multilayer printed wiring board was formed in the same manner as in Example 1 except that the surface of the needle-shaped plating layer was replaced with tin having a thickness of 0.3 μm (see FIG. 1 (f)).

Example 3 In this example, after the treatment (15) in Example 1, the substrate was immersed in 800 g / l of chromic acid at 70 ° C. for 5 minutes to reduce the plating resist surface to 2 μm.
After melting, the gap formed between the plating resist 6 and each of the facing wall surfaces of the conductor circuits 7 and 8 was further increased. Further, instead of the treatment of (16) in Example 1, copper sulfate (0.
05 mol / l), nickel sulfate (0.0039 mol / l), citric acid (0.078 mol / l), sodium hypophosphite (0.33 m
ol / l), boric acid (0.5 mol / l), surfactant (0.5 g)
/ L) to perform a plating treatment using an electroless plating solution (pH = 9), to form a needle-shaped plating layer made of Cu-Ni-P on the surface of the conductor circuit, and then to perform tin borate ( 0.1m
ol / l) and thiourea (1.0 mol / l) using a displacement plating solution (temperature: 50 ° C.), the surface of the needle-shaped plating layer made of Cu—Ni—P was replaced with tin.

In this embodiment, a six-layered multilayer printed wiring board was formed in the same manner as in Embodiment 1 except that the following changes were made in addition to the above (see FIG. 4). . In step (4) in Example 1, DMDG
35 parts by weight of 25% acrylate of cresol novolak type epoxy resin (manufactured by Nippon Kayaku, molecular weight 2500) dissolved in (diethylene glycol dimethyl ether), 12 parts by weight of polyether sulfone (PES), imidazole curing agent (manufactured by Shikoku Chemicals, Inc.) Name: 2E4MZ-CN) 2 parts by weight, 4 parts by weight of caprolactone-modified tris (acroxyethyl) isocyanurate (trade name: Alonix M325) manufactured by Toagosei Co., Ltd., benzophenone as a photoinitiator (manufactured by Kanto Chemical Co., Ltd.) ) 2 parts by weight, 0.2 parts by weight of Michler's ketone (Kanto Chemical) as a photosensitizer, and an epoxy resin particle (manufactured by Sanyo Chemical Co., trade name: Polymer Pole) having an average particle diameter of 3.0 μm was added to this mixture. 10.3 parts by weight,
After mixing 3.09 parts by weight of an average particle size of 0.5 μm, mixing was performed while adding normal methylpyrrolidone (NMP), and the mixture was adjusted to a viscosity of 7 Pa · s with a homodisper stirrer, and then kneaded with three rolls. A photosensitive adhesive solution was obtained.

[0073] In the step (10) in Example 1, a photosensitizing oligomer (molecular weight 4000) obtained by acrylizing 50% of epoxy groups of 60 parts by weight of a cresol novolak type epoxy resin (manufactured by Nippon Kayaku) dissolved in DMDG.
46.67 g, 15.0 g of 80 parts by weight of a bisphenol A type epoxy resin (manufactured by Yuka Shell, Epicoat 1001) dissolved in methyl ethyl ketone, 1.6 g of an imidazole curing agent (manufactured by Shikoku Chemicals, trade name: 2E4MZ-CN), photosensitive property Polyacrylic monomer as a monomer (Nippon Kayaku, trade name: R604)
1.5 g, also polyvalent acrylic monomer (manufactured by Kyoeisha Chemical,
Trade name: DPE6A) 3.0 g, and 0.5 part by weight based on the total weight of these mixtures of 2-ethylhexyl acrylate, butyl acrylate, ethyl acrylate
Mixture A was prepared by mixing and stirring 0.36 g of an acrylate polymer composed of hydroxyacrylate, while benzophenone as a photoinitiator (Kanto Chemical)
2g, Michler's ketone as photosensitizer (Kanto Chemical)
0.2 g was dissolved in 3 g of DMDG heated to 40 ° C. to prepare a mixed solution B, and these were mixed to obtain a liquid resist composition.

(Embodiment 4) In this embodiment, after the process (15) in the first embodiment, the substrate is treated with 12 g of hydrogen peroxide / water.
immersed in an etching solution consisting of 40 g / l of sulfuric acid at 30 ° C. for 3 minutes to dissolve the conductor circuit surface by 2 μm, and to further increase the gap formed between the plating resist 6 and the facing wall surfaces of the conductor circuits 7 and 8. did. And further in Example 1.
Instead of the treatment of (16), copper sulfate (0.05 mol / l), nickel sulfate (0.0039 mol / l), citric acid (0.078 mol / l)
l), electroless plating solution (pH = 9) composed of sodium hypophosphite (0.33 mol / l), boric acid (0.5 mol / l) and surfactant (0.5 g / l) Then, a needle-shaped plating layer made of Cu-Ni-P is formed on the surface of the conductor circuit, and then a displacement plating solution made of tin fluoride fluoride (0.1 mol / l) and thiourea (1.0 mol / l) Using a temperature of 50 ° C.), the surface of the needle-shaped plating layer made of Cu—Ni—P was replaced with tin.

In the present example, a six-layered multilayer printed wiring board was formed in the same manner as in Example 1 except that the following changes were made in addition to the above (see FIG. 5). . In step (4) in Example 1, DMDG
35 parts by weight of 25% acrylate of cresol novolak type epoxy resin (manufactured by Nippon Kayaku, molecular weight 2500) dissolved in (diethylene glycol dimethyl ether), 12 parts by weight of polyether sulfone (PES), imidazole curing agent (manufactured by Shikoku Chemicals, Inc.) Name: 2E4MZ-CN) 2 parts by weight, 4 parts by weight of caprolactone-modified tris (acroxyethyl) isocyanurate (trade name: Alonix M325) manufactured by Toagosei Co., Ltd., benzophenone as a photoinitiator (manufactured by Kanto Chemical Co., Ltd.) ) 2 parts by weight, 0.2 parts by weight of Michler's ketone (Kanto Chemical) as a photosensitizer, and an epoxy resin particle (manufactured by Sanyo Chemical Co., trade name: Polymer Pole) having an average particle diameter of 3.0 μm was added to this mixture. 10.3 parts by weight,
After mixing 3.09 parts by weight of an average particle size of 0.5 μm, mixing was performed while adding normal methylpyrrolidone (NMP), and the mixture was adjusted to a viscosity of 7 Pa · s with a homodisper stirrer, and then kneaded with three rolls. A photosensitive adhesive solution was obtained.

. In the step (10) in Example 1, a photosensitizing oligomer (molecular weight 4000) obtained by acrylizing 50% of epoxy groups of 60 parts by weight of a cresol novolak type epoxy resin (manufactured by Nippon Kayaku) dissolved in DMDG.
46.67 g, 15.0 g of 80 parts by weight of a bisphenol A type epoxy resin (manufactured by Yuka Shell, Epicoat 1001) dissolved in methyl ethyl ketone, 1.6 g of an imidazole curing agent (manufactured by Shikoku Chemicals, trade name: 2E4MZ-CN), photosensitive property Polyacrylic monomer as a monomer (Nippon Kayaku, trade name: R604)
1.5 g, also polyvalent acrylic monomer (manufactured by Kyoeisha Chemical,
Trade name: DPE6A) 3.0 g, and 0.5 part by weight based on the total weight of these mixtures of 2-ethylhexyl acrylate, butyl acrylate, ethyl acrylate
Mixture A was prepared by mixing and stirring 0.36 g of an acrylate polymer composed of hydroxyacrylate, while benzophenone as a photoinitiator (Kanto Chemical)
2g, Michler's ketone as photosensitizer (Kanto Chemical)
0.2 g was dissolved in 3 g of DMDG heated to 40 ° C. to prepare a mixed solution B, and these were mixed to obtain a liquid resist composition.

(Embodiment 5) (12) and
At the time of exposure curing of (13), exposure curing was performed while blowing air at 25 ° C. to cool. At this time, a gap larger by about 0.5 μm than in Example 1 could be formed. In addition, in place of the treatment of (16) in Example 1, a treatment using an etching solution having a trade name of “Mech etch bond CZ” manufactured by Mec Co., Ltd. was performed, and the surface of the conductor circuit was roughened. A six-layer multilayer printed wiring board was formed in the same manner as in Example 1 (see FIG. 6).

(Embodiment 6) In this embodiment, after the process (13) in the embodiment 1, the substrate is immersed in warm water of 90 ° C. for 15 minutes to swell the plating resist 6, and then the embodiment 1
By the processes (14) and (15) in the above, a gap of 4 μm was formed between the plating resist 6 and the wall surfaces of the conductor circuits 7 and 8 facing each other. The gap at this time was larger than that in Example 1. Further, instead of the treatment of (16) in Example 1, copper sulfate (0.05 mol / l), nickel sulfate (0.0039 mol / l), citric acid (0.078 mol / l), sodium hypophosphite (0.33 mol / l) / L), boric acid (0.5mol /
1) Plating using an electroless plating solution (pH = 9) comprising a surfactant (0.5 g / l) to form a needle-like plating layer comprising Cu-Ni-P on the surface of the conductor circuit. Then, tin fluoride borate (0.1 mol / l), thiourea (1.0 m
ol / l) using a displacement plating solution (temperature 50 ° C.)
The surface of the needle-shaped plating layer made of Cu-Ni-P was replaced with tin.

In this example, a six-layered multilayer printed wiring board was formed in the same manner as in Example 1 except that the following changes were made. . In step (4) in Example 1, DMDG
35 parts by weight of 25% acrylate of cresol novolak type epoxy resin (manufactured by Nippon Kayaku, molecular weight 2500) dissolved in (diethylene glycol dimethyl ether), 12 parts by weight of polyether sulfone (PES), imidazole curing agent (manufactured by Shikoku Chemicals, Inc.) Name: 2E4MZ-CN) 2 parts by weight, 4 parts by weight of caprolactone-modified tris (acroxyethyl) isocyanurate (trade name: Alonix M325) manufactured by Toagosei Co., Ltd., benzophenone as a photoinitiator (manufactured by Kanto Chemical Co., Ltd.) ) 2 parts by weight, 0.2 parts by weight of Michler's ketone (Kanto Chemical) as a photosensitizer, and an epoxy resin particle (manufactured by Sanyo Chemical Co., trade name: Polymer Pole) having an average particle diameter of 3.0 μm was added to this mixture. 10.3 parts by weight,
After mixing 3.09 parts by weight of an average particle size of 0.5 μm, mixing was performed while adding normal methylpyrrolidone (NMP), and the mixture was adjusted to a viscosity of 7 Pa · s with a homodisper stirrer, and then kneaded with three rolls. A photosensitive adhesive solution was obtained.

[0080] In the step (10) in Example 1, a photosensitizing oligomer (molecular weight 4000) obtained by acrylizing 50% of epoxy groups of 60 parts by weight of a cresol novolak type epoxy resin (manufactured by Nippon Kayaku) dissolved in DMDG.
46.67 g, 15.0 g of 80 parts by weight of a bisphenol A type epoxy resin (manufactured by Yuka Shell, Epicoat 1001) dissolved in methyl ethyl ketone, 1.6 g of an imidazole curing agent (manufactured by Shikoku Chemicals, trade name: 2E4MZ-CN), photosensitive property Polyacrylic monomer as a monomer (Nippon Kayaku, trade name: R604)
1.5 g, also polyvalent acrylic monomer (manufactured by Kyoeisha Chemical,
Trade name: DPE6A) 3.0 g, and 0.5 part by weight based on the total weight of these mixtures of 2-ethylhexyl acrylate, butyl acrylate, ethyl acrylate
Mixture A was prepared by mixing and stirring 0.36 g of an acrylate polymer composed of hydroxyacrylate, while benzophenone as a photoinitiator (Kanto Chemical)
2g, Michler's ketone as photosensitizer (Kanto Chemical)
0.2 g was dissolved in 3 g of DMDG heated to 40 ° C. to prepare a mixed solution B, and these were mixed to obtain a liquid resist composition.

(Example 7) Instead of the treatment (16) in Example 1, an aqueous solution consisting of 10% by weight of imidazole copper (II) complex, 7% by weight of glycolic acid and 5% by weight of potassium chloride was used as an etching solution. This was sprayed under the conditions of 40 ° C. and 60 seconds, and the surface of the copper conductor circuit was etched to form a roughened layer.
A multi-layer printed wiring board of layers was formed.

(Comparative Example) Basically the same as in Example 1, except that 50% of the epoxy groups of the cresol novolak type epoxy resin (trade name: EOCN-103S, manufactured by Nippon Kayaku) dissolved in DMDG were acrylated. Oligomer (molecular weight 4000), imidazole curing agent (product name: 2E4MZ-CN, manufactured by Shikoku Chemicals Co., Ltd.), acrylic isocyanate that is a photosensitive monomer (product name: Alonix M215, manufactured by Toagosei Co., Ltd.)
), Benzophenone as photoinitiator (Kanto Chemical), Michler's ketone as photosensitizer (Kanto Chemical)
Was mixed with NMP using the following composition, the viscosity was adjusted to 3000 cps with a homodisper stirrer, and then kneaded with three rolls to produce a multilayer printed wiring board. Resist composition; photosensitive epoxy / PES / M215 / BP /
MK / imidazole = 70/30/10/5 / 0.5 / 5

In this comparative example, the liquid resist composition was applied to a substrate to which the surface of the interlayer resin insulating layer was roughened and catalyst nuclei were applied, dried, exposed, developed, and then heated. After curing to form a plating resist, a conductor circuit was formed by electroless plating. Therefore, in this comparative example, no gap is formed between the wall surfaces facing the permanent resist and the conductor circuit.

The multilayer printed wiring boards manufactured in Examples 1 to 7 and Comparative Example were subjected to a heat cycle test at −65 ° C. to 125 ° C. 2,000 times. As a result, Examples 1 to 6
In the multilayer printed wiring board, no crack occurred in the upper and lower interlayer resin insulating layers in contact with the interface between the conductor circuit and the plating resist. On the other hand, in the multilayer printed wiring board of the comparative example, cracks occurred in the upper and lower interlayer resin insulating layers in contact with the interface between the conductor circuit and the plating resist.

In the process of manufacturing a multilayer printed wiring board,
When the polishing is performed until the surface of the permanent resist and the uppermost surface of the conductor circuit including the via hole are aligned on the same plane, the conductor circuit is plastically deformed as shown in FIGS. According to the present invention, as shown in FIG. 3, a multilayer printed wiring board manufactured by further forming an interlayer resin insulating layer on the polished surface on which such protrusions are formed is also subjected to a heat cycle test, It was confirmed that no cracks occurred in the insulating layer.

[0086]

As described above, according to the present invention, since the conductor circuit and the plating resist are prevented from contacting each other, the roughening layer is provided on the surface of the conductor circuit located in the inner layer. There is no stress concentration due to the difference in the coefficient of thermal expansion between the resist and the conductor circuit.In addition, the conductor circuit and the interlayer resin insulation layer are firmly adhered to each other and have excellent heat resistance and electrical characteristics, as well as excellent reliability such as heat cycle characteristics. Printed wiring board can be provided.

[Brief description of the drawings]

FIG. 1 is a view showing one manufacturing process of a multilayer printed wiring board according to the present invention in an example.

FIG. 2 is an enlarged schematic cross-sectional view showing a state of a crack generated from an interface between a plating resist and a conductor circuit toward a resin insulating layer.

FIG. 3 is an enlarged cross-sectional schematic view showing a state after a heat cycle test on a multilayer printed wiring board manufactured by polishing a surface of a plating resist and a conductive circuit in an example.

FIG. 4 is a partial manufacturing process diagram including a process of dissolving the plating resist surface to further increase the gap formed between the wall surfaces of the plating resist and the conductor circuit facing each other.

FIG. 5 is a partial manufacturing process diagram showing a process of melting a surface of a conductive circuit to further increase a gap formed between respective wall surfaces facing the plating resist and the conductive circuit.

FIG. 6 is a partially enlarged cross-sectional view of a multilayer printed wiring board in which a roughened layer on the surface of a conductive circuit is formed by etching.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 substrate 2 inner layer copper pattern 3 insulating layer (interlayer resin insulating layer) 4 adhesive layer (interlayer resin insulating layer) 5 opening for via hole 6 plating resist (permanent resist) 7 outer layer copper pattern (conductor circuit via plating resist) 8 Via hole 9 Copper foil 10 Roughened layer

Continuation of the front page (72) Inventor Motoo Asai 1-1, Ibigawa-cho, Ibi-gun, Gifu Prefecture Ibiden Ogaki-Kita Plant

Claims (8)

[Claims] 1. A multilayer printed wiring board comprising an interlayer resin insulating layer and a conductor circuit layer provided in a portion where no resist is formed via a plating resist on a substrate, wherein the plating resist and the conductor circuit are provided. Characterized by having a gap between the wall surfaces facing each other and a roughened layer on the surface of the conductive circuit. 2. The multilayer printed wiring board according to claim 1, wherein the interlayer resin insulating layer is an adhesive layer for electroless plating. 3. A method of manufacturing a multilayer printed wiring board comprising a substrate and an interlayer resin insulating layer and a conductive circuit layer provided on a portion where a resist is not formed via a plating resist is alternately laminated. a) to (d), that is, (a) forming a photosensitive resin insulating layer on the surface of the interlayer resin insulating layer formed on the substrate, exposing and curing it in a predetermined pattern, and then developing Then, a process of forming a plating resist, (b) a process of forming a conductive circuit by electroless plating in a portion where the plating resist is not formed, and (c) curing and shrinking of the plating resist by heating and curing, the plating resist and the A method for producing a multilayer printed wiring board, comprising: performing a process of forming a gap between wall surfaces facing a conductor circuit; and (d) a process of providing a roughened layer on a surface of the conductor circuit. 4. The method according to claim 3, wherein the interlayer resin insulating layer is formed using an adhesive for electroless plating. 5. The method according to claim 3, wherein a dissolution treatment of the plating resist surface is performed after the treatment (c). 6. The method according to claim 3, wherein a dissolution treatment of the surface of the conductor circuit is performed after the treatment (c). 7. The method according to claim 3, wherein the substrate temperature at the time of exposure and curing in the processing (a) is adjusted to 100 ° C. or less.
The production method described in 1. 8. The method according to claim 3, wherein the substrate is immersed in hot water after the treatment (a), and then a conductor circuit is formed by the treatment (b).