JP2009147387A - Multilayer printed wiring board and method for manufacturing multilayer printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a highly reliable multilayer printed wiring board which prevents occurrence of a crack in a resin portion caused by having a roughened face different in an upper face and side faces of a lower layer conductor circuit. <P>SOLUTION: In a build-up multilayer printed wiring board in which a through-hole whose inside is filled with resin is provided, lower layer conductor circuits whose surfaces are roughened are provided on both sides of a substrate, and an interlayer resin insulating layer and an upper layer conductor circuit whose surface is roughened are further sequentially laminated, the upper face and side faces of the lower layer conductor circuit are roughened by the same type method of roughening. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a wiring board and a printed wiring board having a conductor circuit having a structure capable of preventing the occurrence of cracks in a resin insulating layer.

2. Description of the Related Art In recent years, a multilayer printed wiring board called a so-called multilayer build-up wiring board has attracted attention because of demand for higher density of the multilayer wiring board.
In this multilayer build-up wiring board, copper and other wiring layers and interlayer resin insulation layers are alternately laminated on a resin substrate reinforced with a glass cloth of about 100 to 1000 μm called a core, and sandwich the core. The wiring layers are electrically connected by through holes, and the wiring layers sandwiching the interlayer resin insulation layer are electrically connected by via holes.

Patent Document 1 and the like describe a method of manufacturing such a multilayer build-up wiring board.
According to these publications, first, after forming a through hole and a conductor circuit in a copper clad laminate, the inner wall of the through hole and the surface of the conductor circuit are roughened by blackening-reduction treatment, and the inside of the through hole and the conductor circuit are formed. After the resin is filled in between, the surface of the substrate including the resin filling layer is polished to flatten the resin filling layer and the conductor circuit, and the upper surface of the resin filling layer and the upper surface of the conductor circuit are flushed.

Thereafter, in order to improve the adhesion with the interlayer resin insulation layer, etc., the conductor circuit is subjected to a roughening treatment different from the blackening-reduction treatment, and then the interlayer resin insulation is formed on the conductor circuit and the resin filling layer. A layer was provided to form a through hole for a via hole, and an upper conductor circuit having a via hole was formed on the interlayer resin insulating layer.

When a multilayer printed wiring board is manufactured by the above manufacturing method, no large stress is generated on the inner wall of the through hole, and it is difficult to contact the roughening liquid used to roughen the interlayer resin insulation layer. If the roughened surface is formed by the conversion-reduction treatment, the resin filled inside can be sufficiently retained, and the resin filler does not generate cracks or the like.

On the other hand, the surface of the lower conductor circuit is in contact with various roughening liquids in the manufacturing process, stress is generated due to thermal history, etc., and an interlayer resin insulation layer and via holes are formed thereon, so that the surface is stronger. A roughening method (for example, acicular or porous plating made of a Cu—Ni—P alloy, etching treatment in the presence of oxygen with an organic acid and a cupric complex) has been required.

JP-A-6-283860

However, in the multilayer printed wiring board manufactured by such a method, since the roughening method is different between the side surface and the top surface of the conductor circuit, the degree and direction of expansion and contraction between the top surface and the side surface of the conductor circuit during the heat cycle. Is different.
Accordingly, the expansion and contraction of the resin that is in contact with the conductor circuit is different between the vicinity of the side surface and the vicinity of the upper surface, and this causes a large difference in the resin at the boundary due to the difference in the degree of expansion and contraction. Stress was generated, and cracks sometimes occurred in the interlayer resin insulation layer at the boundary.

Further, in such a conventional method, after filling the resin in the through hole and between the conductor circuits, the resin filling layer is polished and removed, and the upper part of the conductor circuit is also polished and removed, so that the upper surface of the conductor circuit and the resin filling layer are removed. Since the upper surface is the same plane, the polishing process is complicated, and metal fragments generated during polishing of the conductor circuit pierce the resin-filled layer, and accidents such as short circuits between the conductor circuits are likely to occur. .

The present invention has been made to solve such problems of the prior art, and its purpose is to crack the resin portion due to the fact that the upper surface and the side surface of the lower conductor circuit have different roughened surfaces. The present invention provides a highly reliable multilayer printed wiring board that can prevent the occurrence of the above, and a multilayer printed wiring board manufacturing method that can manufacture the multilayer printed wiring board at a low cost by a more simplified method. There is.

As a result of intensive research aimed at realizing the above object, the inventors have come up with an invention having the following contents as a gist.
That is, the multilayer printed wiring board of the present invention is provided with a through hole filled with a resin inside, and on a substrate provided with a lower-layer conductor circuit with a roughened surface on both sides, an interlayer resin insulation layer and In the build-up multilayer printed wiring board in which the upper layer conductor circuit whose surface is roughened is sequentially laminated and formed,
The upper surface and the side surface of the lower conductor circuit are roughened by the same kind of roughening method.

In the multilayer printed wiring board, the thickness of the lower conductor circuit is preferably 30 μm or less.

The method for producing a multilayer printed wiring board of the present invention forms a through hole for a through hole on a substrate on which a metal layer is formed,
Forming a metal layer on the substrate surface including the inner wall of the through hole for the through hole to provide a through hole,
Roughening the substrate surface including the inner wall of the through hole,
After filling the inside of the roughened through hole with resin, the substrate surface is smoothed,
Etch the metal layer on the smoothed substrate surface to form the lower conductor circuit,
Simultaneously roughening the upper surface and side surfaces of the formed lower conductor circuit,
An interlayer resin insulation layer and an upper layer conductor circuit are sequentially stacked on the substrate surface including the roughened lower layer conductor circuit.

In the method for producing a multilayer printed wiring board according to the present invention, the thickness of the metal layer is adjusted to 1 to 10 μm by etching the substrate on which the metal layer is formed before forming the through hole for the through hole. It is desirable to do.

In the method of manufacturing a multilayer printed wiring board, after the interlayer resin insulation layer is formed, the substrate on which the interlayer resin insulation layer is formed is pressed to flatten the surface of the interlayer resin insulation layer. It is desirable.

According to the multilayer printed wiring board of the present invention, a highly reliable multilayer printed wiring which can prevent the occurrence of cracks in the resin portion due to the roughened surface being different from the upper surface and the side surface of the lower conductor circuit. Board can be provided.

Moreover, according to the method for producing a multilayer printed wiring board of the present invention, a highly reliable multilayer printed wiring board can be produced at a low cost by a simplified process.

(A)-(e) is sectional drawing which shows an example of the manufacturing process of the wiring board of this invention. (A)-(d) is sectional drawing which shows a part of manufacturing process of the printed wiring board of this invention. (A)-(d) is sectional drawing which shows a part of manufacturing process of the printed wiring board of this invention. (A)-(d) is sectional drawing which shows a part of manufacturing process of the printed wiring board of this invention. (A)-(c) is sectional drawing which shows a part of manufacturing process of the printed wiring board of this invention. (A)-(c) is sectional drawing which shows a part of manufacturing process of the printed wiring board of this invention. (A)-(d) is sectional drawing which shows a part of manufacturing process of the multilayer printed wiring board which concerns on a comparative example.

The multilayer printed wiring board of the present invention is provided with a through-hole filled with a resin inside, and on a substrate provided with a lower layer conductor circuit having a roughened surface on both sides, an interlayer resin insulation layer and a surface further In a build-up multilayer printed wiring board in which roughened upper layer conductor circuits are sequentially laminated,
The upper surface and the side surface of the lower conductor circuit are roughened by the same kind of roughening method.

According to such a configuration of the present invention, since the upper surface and the side surface of the lower conductor circuit are roughened by the same type of roughening method, they exist in the vicinity of the upper surface of the lower conductor circuit even during a heat cycle. Since the degree of expansion and contraction is almost the same between the resin and the resin in the vicinity of the side surface, no large stress is generated in the resin, and therefore cracks occur in the interlayer resin insulation layer in contact with the lower conductor circuit. Absent.

In the multilayer printed wiring board, in order to maintain the flatness of the upper surface of the interlayer resin insulation layer formed on the lower layer conductor circuit, it is desirable that the thickness of the lower layer conductor circuit is thin. Is preferably 30 μm or less.

In the method for producing a multilayer printed wiring board of the present invention, a through hole for a through hole is formed on a substrate on which a metal layer is formed, and the metal layer is formed on the surface of the substrate including the inner wall of the through hole for the through hole. After roughening the substrate surface including the inner wall of the through hole, filling the inside of the roughened through hole with resin, the substrate surface is smoothed, and the metal layer on the smoothed substrate surface is etched. Forming a lower conductor circuit, and simultaneously roughening the upper and side surfaces of the formed lower conductor circuit, and sequentially placing the interlayer resin insulation layer and the upper conductor circuit on the substrate surface including the roughened lower conductor circuit. It is characterized by being laminated.
According to the configuration of the present invention, the highly reliable multilayer printed wiring board can be manufactured at a low cost by a more simplified method.

Hereinafter, a method for producing the multilayer printed wiring board of the present invention will be described.
(1) First, a substrate in which through holes are formed and metal layers are formed on both surfaces of the substrate is manufactured.
Normally, through holes for through holes are formed on a substrate on which a metal layer such as a copper clad laminate is formed, and then through holes are formed by electroless plating, but glass epoxy substrates, polyimide substrates, ceramic substrates After forming an electroless plating adhesive layer on a substrate such as a through-hole, the surface of the electroless plating adhesive layer is roughened to a roughened surface, and then electroless plating is performed. A method or the like can also be used.
When a copper clad laminate is used, the conductive layer on the surface is also thickened by electroless plating. Therefore, it is desirable to reduce the thickness of the conductive layer to about 1 to 10 μm by etching before performing electroless plating. .

(2) After the step (1), the conductor layer in the through hole is roughened.
The roughening method is not particularly limited, and examples thereof include etching treatment, blackening reduction treatment, plating treatment, and the like, but roughening in the through hole is a roughened surface with a very high unevenness. Since it is not necessary to form, the roughened surface can be formed by using the blackening reduction treatment or the like.

When performing the blackening reduction treatment, a blackening bath (oxidation bath) made of an aqueous solution containing NaOH (20 g / l), NaClO ₂ (50 g / l), Na ₃ PO ₄ (15.0 g / l), and, NaOH (2.7g _{/ l),} a method of forming a roughened surface by using a reducing bath of an aqueous solution containing NaBH 4 a (1.0 g / l) is desired.

(3) After the roughening treatment, a resin filler is filled into the through hole and dried, and then both surfaces of the substrate are flattened, and then a conductor circuit is formed by etching.
The resin filler used for filling the inside of the through hole is not particularly limited, and examples thereof include a material having a bisphenol F type epoxy resin or the like as a main component and not having a high viscosity.

The planarization of the conductor layer on the surface of the substrate can be performed by polishing treatment, and the lower layer conductor circuit can be formed by performing etching after forming a conductor circuit pattern-like etching resist on the surface.
The thickness of the conductor circuit formed by this process is preferably thinner than the conventional one, and is preferably 30 μm or less. This is because when the interlayer resin insulation layer is formed, the unevenness is not excessively increased between the portion where the conductor circuit is formed and the portion where the conductor circuit is not formed.

(4) After the step (3), the conductor circuit formed on the substrate is roughened to form a roughened surface or a roughened layer.
The roughened surface or the roughened layer is preferably formed by any one of a polishing process, an etching process, a blackening reduction process, and a plating process.

When the roughening layer is formed by the above plating treatment, copper sulfate (1 to 40 g / l), nickel sulfate (0.1 to 6.0 g / l), citric acid (10 to 20 g / l), hypochlorous acid, PH = 9 containing sodium phosphate (10-100 g / l), boric acid (10-40 g / l), surfactant (manufactured by Nissin Chemical Industry Co., Ltd., Surfinol 465) (0.01-10 g / l) A method of forming a roughened layer made of a Cu-Ni-P alloy by performing electroless plating in an electroless plating bath is desirable.
This is because the crystal structure of the coating deposited in this range becomes a needle-like structure, and thus the anchor effect is excellent. In addition to the above compounds, complexing agents and additives may be added to the electroless plating bath.

When performing the blackening reduction treatment, conditions similar to the conditions for forming a roughened surface in the through hole can be used in the step (2).

Examples of the etching treatment include a method in which an etching solution composed of a cupric complex and an organic acid is allowed to act in the presence of oxygen. In this case, a method of forming a roughened surface on the conductor circuit by spraying the etching solution is desirable.
In this case, etching proceeds by the chemical reaction of the following formulas (1) and (2).

The cupric complex is preferably an azole cupric complex. This cupric complex of azoles acts as an oxidizing agent that oxidizes metallic copper and the like. Examples of azoles include diazole, triazole, and tetrazole. Among these, imidazole, 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-undecylimidazole and the like are desirable. As for content of the cupric complex of azoles in the said etching liquid, 1 to 15 weight% is desirable. This is because it is excellent in solubility and stability and can also dissolve noble metals such as Pd constituting the catalyst nucleus.

Moreover, in order to dissolve copper oxide, an organic acid is blended with a cupric complex of azoles. Specific examples of the organic acid include, for example, formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, acrylic acid, crotonic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, maleic acid, benzoic acid, Examples include glycolic acid, lactic acid, malic acid, and sulfamic acid. These may be used alone or in combination of two or more.

The content of the organic acid in the etching solution is desirably 0.1 to 30% by weight. This is because the solubility of oxidized copper can be maintained and the dissolution stability can be ensured.
As shown in the above formula (2), the generated cuprous complex is dissolved by the action of an acid, combined with oxygen to become a cupric complex, and again contributes to the oxidation of copper.

In order to assist the dissolution of copper and the oxidizing action of azoles, halogen ions such as fluorine ions, chlorine ions and bromine ions may be added to the etching solution. In addition, halogen ions can be supplied by adding hydrochloric acid, sodium chloride, or the like. The halogen ion content in the etching solution is preferably 0.01 to 20% by weight. This is because the adhesion between the formed roughened surface and the interlayer resin insulation layer is excellent.

When preparing the etching solution, a cupric complex of azoles and an organic acid (use one having a halogen ion if necessary) are dissolved in water. Further, as the etching solution, a commercially available etching solution, for example, trade name “MEC Etch Bond” manufactured by MEC is used. The etching amount when the above etching solution is used is preferably 0.1 to 10 μm, and more preferably 1 to 5 μm. If the etching amount exceeds 10 μm, poor connection between the formed rough surface and the via-hole conductor is caused. On the other hand, if the etching amount is less than 0.1 μm, the adhesion with the interlayer resin insulation layer formed thereon is poor. This is because it becomes insufficient.

The roughened surface formed by the above method may be covered with a metal or noble metal layer (hereinafter referred to as a metal layer) having an ionization tendency larger than copper and equal to or less than titanium. Examples of such metals include titanium, aluminum, zinc, iron, indium, thallium, cobalt, nickel, tin, lead, and bismuth. Moreover, as a noble metal, gold | metal | money, silver, platinum, palladium etc. are mentioned, for example. These may be used alone or in combination of two or more to form a plurality of layers.

These metal layers cover the roughened layer, and even if the interlayer resin insulating layer is roughened, the local electrode reaction is prevented and the conductor circuit is prevented from dissolving. The thickness of these metals is preferably 0.1 to 2 μm.

Of the metals constituting the metal layer, tin is desirable. When tin can form a thin layer by electroless displacement plating and can follow the roughened layer.
In the case of forming a metal layer made of tin, displacement plating is performed using a solution containing tin borofluoride-thiourea or a solution containing tin chloride-thiourea. In this case, an Sn layer of about 0.1 to 2 μm is formed by the substitution reaction of Cu—Sn.
In the case of forming a metal layer made of a noble metal, a method such as sputtering or vapor deposition can be employed.

(5) A roughened surface-forming resin composition layer is formed by applying and drying a roughened surface-forming resin composition containing an organic solvent on a substrate surface including a conductor circuit having a roughened surface formed as described above. Is provided.

The resin composition for forming a roughened surface comprises an acid, an alkali, and an oxidizing agent in an uncured heat-resistant resin matrix that is hardly soluble in a roughening liquid consisting of at least one selected from acids, alkalis, and oxidizing agents. A material in which a substance soluble in at least one roughening liquid selected from the above is dispersed is desirable.
As used herein, the terms “sparingly soluble” and “soluble” refer to the term “soluble” for the sake of convenience when the dissolution rate is relatively high when immersed in the same roughening solution for the same time. Those having a low dissolution rate are referred to as “slightly soluble” for convenience.

As the heat-resistant resin matrix, for example, a thermosetting resin or a composite of a thermosetting resin (including those obtained by sensitizing part of a thermosetting group) and a thermoplastic resin can be used.

As said thermosetting resin, an epoxy resin, a phenol resin, a polyimide resin, a thermosetting polyolefin resin etc. are mentioned, for example. Moreover, when sensitizing the said thermosetting resin, methacrylic acid, acrylic acid, etc. are used, and a thermosetting group is (meth) acrylated. In particular, epoxy resin (meth) acrylate is most suitable.

As said epoxy resin, a novolak-type epoxy resin, an alicyclic epoxy resin, etc. can be used, for example.
As said thermoplastic resin, polyether sulfone, polysulfone, polyphenylene sulfone, polyphenylene sulfide, polyphenyl ether, polyether imide, etc. can be used, for example.

The substance soluble in the roughening liquid consisting of at least one selected from acids, alkalis and oxidizing agents is at least one selected from inorganic particles, resin particles, metal particles, rubber particles, liquid phase resins and liquid phase rubbers. It is desirable to be a seed.

Examples of the inorganic particles include silica, alumina, calcium carbonate, talc, and dolomite. These may be used alone or in combination of two or more.
The alumina particles can be dissolved and removed with hydrofluoric acid, and the calcium carbonate can be dissolved and removed with hydrochloric acid. Sodium-containing silica and dolomite can be dissolved and removed with an alkaline aqueous solution.

Examples of the resin particles include amino resins (melamine resins, urea resins, guanamine resins, etc.), epoxy resins, bismaleimide-triazine resins, and the like. These may be used alone or in combination of two or more.
In addition, the said epoxy resin can be arbitrarily manufactured by selecting what kind of oligomer and hardening | curing agent what melt | dissolves in an acid and an oxidizing agent, and a thing hardly soluble in these. For example, a resin obtained by curing a bisphenol A type epoxy resin with an amine curing agent dissolves very well in chromic acid, but a resin obtained by curing a cresol novolac type epoxy resin with an imidazole curing agent is difficult to dissolve in chromic acid. .

The resin particles must be previously cured. If not cured, the resin particles are dissolved in a solvent that dissolves the resin matrix, so they are uniformly mixed, and only the resin particles cannot be selectively dissolved and removed with an acid or an oxidizing agent. is there.

Examples of the metal particles include gold, silver, copper, tin, zinc, stainless steel, and aluminum. These may be used alone or in combination of two or more.

Examples of the rubber particles include acrylonitrile-butadiene rubber, polychloroprene rubber, polyisoprene rubber, acrylic rubber, polysulfuric rigid rubber, fluorine rubber, urethane rubber, silicone rubber, ABS resin, and the like. These may be used alone or in combination of two or more.

As the liquid phase resin, an uncured solution of the thermosetting resin can be used. As a specific example of such a liquid phase resin, for example, a mixed liquid of an uncured epoxy oligomer and an amine curing agent. Etc.
As the liquid phase rubber, for example, an uncured solution of the rubber can be used.

When preparing the photosensitive resin composition using the liquid phase resin or the liquid phase rubber, the heat resistant resin matrix and the soluble material are not uniformly compatible (that is, so as to be phase separated). It is necessary to select a substance.
By mixing the heat-resistant resin matrix selected according to the above criteria and a soluble substance, the liquid-phase resin or liquid-phase rubber “islands” are dispersed in the “sea” of the heat-resistant resin matrix. Alternatively, it is possible to prepare a photosensitive resin composition in which “islands” of a heat-resistant resin matrix are dispersed in a “sea” of a liquid phase resin or a liquid phase rubber.

And after hardening the photosensitive resin composition of such a state, a roughened surface can be formed by removing the liquid phase resin or liquid phase rubber of "the sea" or "the island".

Examples of the acid used as the roughening solution include phosphoric acid, hydrochloric acid, sulfuric acid, and organic acids such as formic acid and acetic acid. Among these, it is desirable to use an organic acid. This is because when the roughening treatment is performed, the metal conductor layer exposed from the via hole is hardly corroded.
As the oxidizing agent, for example, an aqueous solution of chromic acid or alkaline permanganate (such as potassium permanganate) is preferably used.
Moreover, as an alkali, aqueous solutions, such as sodium hydroxide and potassium hydroxide, are desirable.

In the present invention, when the inorganic particles, the metal particles, and the resin particles are used, the average particle size is desirably 10 μm or less.
In particular, by using a combination of coarse particles having an average particle size of less than 2 μm and relatively large average particles and fine particles having a relatively small average particle size, Dissolving residue can be eliminated, the amount of palladium catalyst under the plating resist can be reduced, and a shallow and complicated roughened surface can be formed. By forming such a complicated roughened surface, a practical peel strength can be maintained even on a shallow roughened surface.

By combining the above coarse particles and fine particles, a shallow and complicated roughened surface can be formed because the particles used are coarse particles with an average particle size of less than 2 μm, so these particles are dissolved and removed. However, the anchor formed is shallow, and the particles to be removed are a mixture of coarse particles having a relatively large particle size and fine particles having a relatively small particle size. Is complicated.
In this case, since the particle size used is coarse and less than 2 μm in average particle size, the roughening does not proceed excessively and voids are not generated, and the formed interlayer resin insulation layer is excellent in interlayer insulation. ing.

The coarse particles preferably have an average particle size of more than 0.8 μm and less than 2.0 μm, and the fine particles preferably have an average particle size of 0.1 to 0.8 μm.
In this range, the depth of the roughened surface is approximately Rmax = 3 μm, and the semi-additive method not only easily removes the electroless plated film but also easily removes the Pd catalyst under the electroless plated film. This is because a practical peel strength of 1.0 to 1.3 kg / cm can be maintained.

The content of the organic solvent in the roughened surface-forming resin composition is desirably 10% by weight or less.
A roll coater, a curtain coater, etc. can be used when apply | coating the resin composition for roughening surface formation.

(6) After the roughened surface-forming resin composition layer formed in (5) above is dried to a semi-cured state, a via hole opening is provided.
When the roughened surface-forming resin composition layer is dried, the thickness of the resin composition layer on the conductor circuit pattern is thin, and the thickness of the interlayer resin insulation layer on the plain layer having a large area is large. In addition, since there are many irregularities in the interlayer resin insulation layer due to the irregularities of the conductor circuit and the conductor circuit non-formed part, using a metal plate or a metal roll, press while heating, the interlayer resin It is desirable to planarize the surface of the insulating layer.

The via-hole opening is formed by performing development processing after exposing the roughened surface-forming resin composition layer to ultraviolet rays or the like. When performing the exposure development process, the side of the photomask (preferably a glass substrate) on which the black circle pattern is drawn is drawn on the portion corresponding to the above-described opening for the via hole. It mounts in the state closely_contact | adhered to the resin composition layer for roughening surface formation, and it exposes and develops.

(7) Next, the roughened surface-forming resin composition layer is cured to form an interlayer resin insulation layer, and the interlayer resin insulation layer is roughened.
In the roughening treatment, at least one soluble substance selected from inorganic particles, resin particles, metal particles, rubber particles, liquid phase resins, and liquid phase rubbers present on the surface of the interlayer resin insulating layer is treated with the above acid. Removing by using a roughening solution such as an oxidizing agent or an alkali. As for the depth of a roughening surface, about 1-5 micrometers is desirable.

(8) Next, catalyst nuclei are imparted to the substrate on which the roughening treatment has been applied to the interlayer resin insulation layer.
For imparting the catalyst nucleus, it is desirable to use a noble metal ion or a noble metal colloid. Generally, palladium chloride or a palladium colloid is used. It is desirable to perform heat treatment to fix the catalyst core. Palladium is preferable as such a catalyst nucleus.

(9) Next, an electroless plating film is formed on the entire roughened surface.
Examples of the plating solution composition include NiSO ₄ (0.001 to 0.003 mol / l), copper sulfate (0.02 to 0.04 mol / l), tartaric acid (0.08 to 0.15 mol / l), and water. An aqueous solution containing sodium oxide (0.03-0.08 mol / l) and 37% formaldehyde (0.03-0.06 mol / l) is desirable. The thickness of the electroless plating film is desirably 0.1 to 5 μm, and more desirably 0.5 to 3 μm.

(10) Next, a photosensitive resin film (dry film) is laminated on the electroless plating film, and a photomask (preferably a glass substrate) on which a plating resist pattern is drawn is placed in close contact with the photosensitive resin film. A plating resist pattern is formed by performing exposure and development processes.

(11) Next, electrolytic plating is performed on the plating resist non-formation portion to form a conductor circuit and a via hole.
Here, as the electrolytic plating, it is desirable to use copper plating, and the thickness is desirably 1 to 20 μm.

(12) Further, after removing the plating resist, the electroless plating film is dissolved and removed with a mixed solution of sulfuric acid and hydrogen peroxide or an etching solution such as sodium persulfate, ammonium persulfate, ferric chloride, or cupric chloride. And an independent conductor circuit. Thereafter, if necessary, the palladium catalyst nucleus is dissolved and removed with chromic acid or the like.

(13) Next, steps (4) to (12) are repeated to provide a further upper conductor circuit, and a flat conductor pad or via hole functioning as a solder pad is formed thereon. Finally, by forming a solder resist layer, solder bumps, and the like, the production of the multilayer multilayer printed wiring board is completed. In addition, although the following method is based on a semi-additive method, you may employ | adopt a full additive method.
In the following, description will be given based on examples.

Example 1
A. Preparation of photosensitive resin composition 34 parts by weight of resin solution prepared by dissolving 25% acrylate of cresol novolak type epoxy resin (manufactured by Nippon Kayaku Co., Ltd., molecular weight: 2500) in diethylene glycol dimethyl ether (DMDG), imidazole curing agent (Shikoku Chemicals) 2 parts by weight, 2E4MZ-CN), 4 parts by weight of caprolactone-modified tris (acryloxyethyl) isocyanurate (trade name: Aronix M325, manufactured by Toagosei Co., Ltd.) as a photo-sensitive monomer, benzophenone (photopolymerization initiator) 2 parts by weight of Kanto Chemical Co., Ltd., 0.2 parts by weight of Michler's ketone (manufactured by Kanto Chemical Co., Ltd.) as a photosensitizer, 10 parts by weight of photosensitive monomer (KAYAMER PM-21, manufactured by Nippon Kayaku Co., Ltd.), and epoxy resin 15 parts by weight of particles (polymer pole manufactured by Sanyo Chemical Co., Ltd.) with an average particle size of 1.0 μm After mixing 10 parts by weight of an average particle size of 0.5 μm, 30.0 parts by weight of N-methylpyrrolidone (NMP) was added and mixed, adjusted to a viscosity of 7 Pa · s with a homodisper stirrer, and then 3 A photosensitive resin composition (interlayer resin insulating material) was prepared by kneading with a roll.

B. Method for manufacturing printed wiring board
(1) A copper-clad laminate in which a 12 μm copper foil 18 is laminated on both surfaces of a substrate 1 made of glass epoxy resin or BT (bismaleimide triazine) resin having a thickness of 0.6 mm was used as a starting material (FIG. 1 ( a)).
(2) First, the copper-clad laminate is etched using an etchant such as hydrogen peroxide / sulfuric acid to reduce the thickness of the copper foil 18 to 5 μm (FIG. 1 (b)). Then, the substrate was washed with water and then drilled to form a through hole 1a for a through hole (see FIG. 1C).

(3) Next, as the plating solution, NiSO ₄ (0.001 to 0.003 mol / l), copper sulfate (0.02 to 0.04 mol / l), tartaric acid (0.08 to 0.15 mol / l) Electroless plating is performed using an aqueous solution containing sodium hydroxide (0.03 to 0.08 mol / l) and 37% formaldehyde (0.03 to 0.06 mol / l). A conductor layer 8 made of 29 μm copper and a through hole 9 were formed (see FIG. 1D).

(4) The substrate on which the through hole 9 and the conductor layer 8 are formed is washed with water and dried, and then an aqueous solution containing NaOH (10 g / l), NaClO ₂ (40 g / l), and Na ₃ PO ₄ (16 g / l) is added. Conductive layer including through hole 9 after performing blackening treatment using blackening bath (oxidation bath) and reduction treatment using an aqueous solution containing NaOH (19 g / l) and NaBH ₄ (5 g / l). Roughened surfaces 8a and 9a were formed on the entire surface of 8 (see FIG. 1 (e)).

(5) Next, a resin filler 10 containing a bisphenol F-type epoxy resin is filled in the through hole 9 and heated and dried at 100 ° C. for 10 minutes (see FIG. 2A), and then one side of the substrate is removed. The conductor layer on the substrate surface was flattened by buffing, and then the other surfaces were flattened by the same method (see FIG. 2B).
As a result, the thickness of the conductor layer 8 made of copper on the substrate surface was 23.8 μm.

(6) A commercially available photosensitive dry film is attached to the surface of the conductor layer 8 by thermocompression bonding, and a 5 mm thick soda lime glass substrate in which a plating resist non-formed portion is drawn as a mask pattern by a chrome layer, The side on which the chromium layer was formed was brought into close contact with the photosensitive dry film, exposed at 110 mJ / cm ² and then developed with 0.8% sodium carbonate to provide an etching resist 11 having a thickness of 15 μm (FIG. 2). (See (c)).

(7) Next, an etching process is performed with a mixed solution of sulfuric acid and hydrogen peroxide to dissolve and remove the portion of the conductor layer 8 where the etching resist is not formed, thereby forming the conductor circuit (including the through hole 9) 4. did. (See FIG. 2 (d)).

(8) After washing the substrate with water and acid degreasing, soft etching is performed, and then an etching solution is sprayed on both sides of the substrate to spray the surface of the lower conductor circuit 4, the land surface of the through hole 9, and the inner wall. Thus, roughened surfaces 4a and 9a are formed on the entire surface of the lower conductor circuit 4, and a 0.05 μm thick Sn layer is further provided on the roughened surfaces 4a and 9a (see FIG. 3A). ). However, the Sn layer is not shown.

In the etching, a mixture of 10 parts by weight of imidazole copper (II) complex, 7 parts by weight of glycolic acid, 5 parts by weight of potassium chloride and 78 parts by weight of ion-exchanged water was used as an etching solution. In addition, the Sn layer is obtained by immersing the substrate in an electroless tin substitution plating bath containing tin borofluoride (0.1 mol / l) and thiourea (1.0 mol / l) at pH = 1.2 and a temperature of 50 ° C. Formed by.

(9) The photosensitive resin composition prepared by the method described in A above is applied on both sides of the substrate after the processing in (8) above using a roll coater and left in a horizontal state for 20 minutes. Then, drying was performed at 60 ° C. for 30 minutes to form a photosensitive resin composition layer (interlayer resin insulating layer) 2 having a thickness of 30 μm (see FIG. 3B). Furthermore, a polyethylene terephthalate film was stuck on the photosensitive resin composition layer 2 via an adhesive.

(10) A black circle is drawn on a 5 mm thick soda lime glass substrate in which a black circle with a thickness of 5 μm is drawn on both sides of the substrate 1 on which the photosensitive resin composition layer 2 is formed in (9) above by shading ink. The exposed side was brought into close contact with the photosensitive resin composition layer 2 and exposed at 3000 mJ / cm ² intensity with an ultrahigh pressure mercury lamp, and then spray-developed with a DMDG solution to form a via hole opening 6 having a diameter of 100 μm. Thereafter, heat treatment was performed at 100 ° C. for 1 hour and at 150 ° C. for 5 hours to form an interlayer resin insulating layer 2 having a thickness of 50 μm having via hole openings 6 having excellent dimensional accuracy corresponding to a photomask film. (See FIG. 3C). Note that the roughened layer was partially exposed in the opening serving as the via hole. Then, it pressed, using a metal roll, heating, and planarized the surface of the interlayer resin insulation layer.

(11) The surface of the interlayer resin insulation layer 2 is roughened by immersing the substrate having the via hole openings 6 in a chromic acid aqueous solution to dissolve and remove the epoxy resin particles present on the surface of the interlayer resin insulation layer 2. The surface (depth 5 μm) was then immersed in a neutralized solution (manufactured by Shipley Co., Ltd.) and washed with water (see FIG. 3D).
Furthermore, a catalyst catalyst was attached to the surface of the interlayer resin insulation layer 2 and the inner wall surface of the via hole opening 6 by applying a palladium catalyst (manufactured by Atotech) to the surface of the roughened substrate.

(12) Next, the substrate was immersed in an electroless copper plating aqueous solution having the following composition to form an electroless copper plating film 12 having a thickness of 3 μm on the entire rough surface (see FIG. 4A).
[Electroless plating aqueous solution]
EDTA 150 g / l
Copper sulfate 20 g / l
HCHO 30 ml / l
NaOH 40 g / l
α, α'-bipyridyl 80 mg / l
Polyethylene glycol (PEG) 0.1 g / l
[Electroless plating conditions]
30 minutes at a liquid temperature of 70 ° C

(13) A commercially available photosensitive dry film is attached to the electroless copper plating film 12 by thermocompression bonding, and a 5 mm thick soda lime glass substrate in which a plating resist non-formation portion is drawn as a mask pattern by a chromium layer. The side on which the chromium layer was formed was brought into close contact with the photosensitive dry film, exposed at 110 mJ / cm ² , and then developed with 0.8% sodium carbonate to provide a plating resist 3 having a thickness of 15 μm (see FIG. 4 (b)).

(14) Next, electrolytic copper plating was performed under the following conditions to form an electrolytic copper plating film 13 having a thickness of 15 μm (see FIG. 4C).
(Electrolytic plating aqueous solution)
Sulfuric acid 180 g / l
Copper sulfate 80 g / l
Additive 1 ml / l
(Manufactured by Atotech Japan, Kaparaside GL)
[Electrolytic plating conditions]
Current density 1.2 A / dm ²
Time 30 minutes Temperature Room temperature

(15) After stripping and removing the plating resist 3 with 5% KOH, the electroless plating film 12 under the plating resist 3 is dissolved and removed by etching with a mixed solution of sulfuric acid and hydrogen peroxide, and the electroless copper plating film A conductor circuit (including via hole 7) 5 having a thickness of 18 μm and formed of 12 and electrolytic copper plating film 13 was formed. Furthermore, it was immersed in a solution containing 800 g / l of chromic acid for 1 to 2 minutes to remove the palladium catalyst remaining on the surface of the interlayer resin insulation layer 2 (see FIG. 4D).

(16) Next, the conductor circuit (including via hole 7) is sprayed by spraying the etching (etching solution containing cupric complex and organic acid) having the same composition as the solution used in the step (8). A roughened surface was formed on 5 (see FIG. 5A). Further, an Sn layer having a thickness of 0.05 μa was provided on the roughened surface. However, the Sn layer is not shown.

(17) By repeating the above steps (9) to (16), an upper interlayer resin insulation layer and a conductor circuit were formed to obtain a multilayer wiring board (FIGS. 5B to 6B). )reference).

(18) Next, a photosensitizing agent obtained by acrylating 50% of an epoxy group of a cresol novolac type epoxy resin (manufactured by Nippon Kayaku Co., Ltd.) dissolved in diethylene glycol dimethyl ether (DMDG) to a concentration of 60% by weight. 46.67 parts by weight of oligomer (molecular weight: 4000), 80% by weight of bisphenol A type epoxy resin dissolved in methyl ethyl ketone (product name: Epicoat 1001 manufactured by Yuka Shell Co., Ltd.) 6.67 parts by weight, also bisphenol A type epoxy 6.67 parts by weight of resin (manufactured by Yuka Shell, trade name: Epicoat E-1001-B80), 1.6 parts by weight of imidazole curing agent (trade name: 2E4MZ-CN, manufactured by Shikoku Kasei), photosensitive monomer ( KAYAMER PM-21 manufactured by Nippon Kayaku Co., Ltd. 6 parts by weight, levelin made of acrylic ester polymer 0.36 parts by weight of an agent (manufactured by Kyoei Chemical Co., Ltd., trade name: Polyflow No. 75) is placed in a container, stirred and mixed to prepare a mixed composition, and Irgacure I is used as a photopolymerization initiator for this mixed composition. By adding 2.0 parts by weight of -907 (manufactured by Ciba Geigy), 0.2 parts by weight of DETX-S (manufactured by Nippon Kayaku Co., Ltd.) as a photosensitizer, and 0.6 parts by weight of DMDG, the viscosity is 25 ° C. A solder resist composition adjusted to 1.4 ± 0.3 Pa · s was obtained.
Viscosity measurement was performed using a B-type viscometer (DVL-B type, manufactured by Tokyo Keiki Co., Ltd.). In the case of 4 or 6 rpm, the rotor No. 3 according.

(19) Next, the solder resist composition is applied to both surfaces of the multilayer wiring board at a thickness of 20 μm, and after a drying treatment at 70 ° C. for 20 minutes and 70 ° C. for 30 minutes, the chromium layer The soda lime glass substrate having a thickness of 5 mm on which the pattern of the solder resist opening is drawn is exposed to 1000 mJ / cm ² with the solder resist layer in close contact with the side on which the chromium layer is drawn, and developed with a DMTG solution. Processed to form 200 μm diameter openings.
Further, the solder resist layer is cured by heat treatment at 80 ° C. for 1 hour, 100 ° C. for 1 hour, 120 ° C. for 1 hour, and 150 ° C. for 3 hours. A 20 μm solder resist layer 14 was formed.

(20) Next, the substrate on which the solder resist layer 14 is formed is coated with nickel chloride (30 g / l), sodium hypophosphite (10 g / l), and sodium citrate (10 g / l). The nickel plating layer 15 having a thickness of 5 μm was formed in the opening by dipping in an electrolytic nickel plating solution for 20 minutes. Further, the substrate was added to an electroless plating solution containing potassium gold cyanide (2 g / l), ammonium chloride (75 g / l), sodium citrate (50 g / l) and sodium hypophosphite (10 g / l). A gold plating layer 16 having a thickness of 0.03 μm was formed on the nickel plating layer 15 by dipping for 23 seconds under the condition of ° C.

(21) Thereafter, a solder paste is printed on the opening of the solder resist layer 14 and reflowed at 200 ° C. to form solder bumps (solder bodies) 17. A multilayer wiring printed board having the solder bumps 17 is manufactured. (See FIG. 6 (c)).

(Comparative Example 1)
Instead of the steps (1) to (8), the following steps (1) to (4) are performed to flatten the surface layer of the through hole 9 and the resin filler 10 and the surface of the lower conductor circuit 4. Then, the resin filler 10 and the side surface 4a of the lower conductor circuit 4 are firmly attached via the roughened surface, and the inner wall surface 9a of the through hole 9 and the resin filler 10 are firmly attached via the roughened surface. After obtaining an insulative insulating substrate (see FIGS. 7A to 7D), the same processes as in the above (9) to (21) of the present invention were performed to obtain a multilayer printed wiring board.

(1) A copper-clad laminate in which 18 μm copper foil 8 is laminated on both surfaces of a substrate 1 made of glass epoxy resin or BT (bismaleimide triazine) resin having a thickness of 0.6 mm was used as a starting material (FIG. 1 ( a)). First, the copper-clad laminate was drilled, subjected to electroless plating, and etched into a pattern to form the lower conductor circuits 4 and the through holes 9 on both surfaces of the substrate 1.

(2) The substrate on which the through hole 9 and the lower conductor circuit 4 are formed is washed with water and dried, and then an aqueous solution containing NaOH (10 g / l), NaClO ₂ (40 g / l), and Na ₃ PO ₄ (16 g / l). A lower layer including the through hole 9 by performing a blackening treatment using a blackening bath (oxidation bath) and a reduction treatment using an aqueous solution containing NaOH (19 g / l) and NaBH ₄ (5 g / l) as a reducing bath. Roughened surfaces 4a and 9a were formed on the entire surface of the conductor circuit 4 (see FIG. 1B).

(3) A resin filler 10 containing a bisphenol F-type epoxy resin is applied to one side of the substrate using a roll coater to fill the space between the lower conductor circuits 4 or the through holes 9 and heat-dry. Similarly, the other surface was filled with the resin filler 10 between the conductor circuits 4 or in the through holes 9 and dried by heating (see FIG. 1C).

(4) One side of the substrate after the processing in (3) above is applied to the surface of the inner layer copper pattern 4 or the land surface of the through hole 9 by belt sander polishing using # 600 belt polishing paper (manufactured by Sankyo Rikagaku). Polishing was performed so that the resin filler 10 did not remain, and then buffing was performed to remove scratches due to the belt sander polishing. Such a series of polishing was similarly performed on the other surface of the substrate.
Next, the resin filler 10 was cured by heat treatment at 100 ° C. for 1 hour, 120 ° C. for 3 hours, 150 ° C. for 1 hour, and 180 ° C. for 7 hours. Thereafter, the same steps as (9) to (21) of Example 1 were performed to obtain a multilayer printed wiring board.

The printed wiring boards of Example 1 and Comparative Example 1 thus manufactured were subjected to a heat cycle test in which the heat cycle held at -55 ° C for 30 minutes and then held at 125 ° C for 30 minutes was repeated 1000 times. The portion including the conductor circuit 4 was cross-cut, and the boundary portion between the lower layer conductor circuit 4 and the interlayer resin insulation layer 2 was observed with a microscope, thereby examining the occurrence of cracks in the interlayer resin insulation layer 2.

As a result, in the multilayer printed wiring board according to Example 1, no cracks were found in the interlayer resin insulating layer near the lower conductor circuit for all of the boards manufactured under the same conditions. In the printed wiring board, a crack was found in the interlayer resin insulating layer in a part close to the edge of the lower conductor circuit 4 in a part.

1 Substrate 2 Interlayer resin insulation layer (adhesive layer for electroless plating)
3 Plating resist 4 Lower layer conductor circuit (inner layer copper pattern)
4a Roughened surface 5 Upper layer conductor circuit 6 Via hole opening 7 Via hole 8 Conductor layer 9 Through hole 9a Roughened surface 10 Resin filler 11 Etching resist 12 Electroless plating film 13 Electroplating film 14 Solder resist layer 15 Nickel plating Layer 16 Gold plating layer 17 Solder bump

Claims (5)

A through-hole filled with resin is provided inside, and a lower-layer conductor circuit with a roughened surface is provided on both sides, and then an interlayer resin insulation layer and an upper-layer conductor circuit with a roughened surface are sequentially formed. In the build-up multilayer printed wiring board formed by lamination,
A multilayer printed wiring board, wherein an upper surface and a side surface of the lower conductor circuit are roughened by the same kind of roughening method. The multilayer printed wiring board according to claim 1, wherein the lower conductor circuit has a thickness of 30 μm or less. Through holes for through holes are formed in the substrate on which the metal layer is formed,
A metal layer is formed on the substrate surface including the inner wall of the through hole for the through hole to provide a through hole,
Roughening the substrate surface including the inner wall of the through hole,
After filling the inside of the roughened through hole with resin, the substrate surface is smoothed,
Etch the metal layer on the smoothed substrate surface to form the lower conductor circuit,
Simultaneously roughening the upper surface and the side surface of the formed lower conductor circuit,
A method for producing a multilayer printed wiring board, comprising sequentially laminating an interlayer resin insulating layer and an upper layer conductor circuit on a substrate surface including a roughened lower layer conductor circuit. The multilayer printed wiring board according to claim 3, wherein the thickness of the metal layer is adjusted to 1 to 10 μm by etching the substrate on which the metal layer is formed before forming the through hole for the through hole. Method. 5. The multilayer printed wiring board according to claim 3, wherein after the formation of the interlayer resin insulation layer, the surface of the interlayer resin insulation layer is planarized by pressing the substrate on which the interlayer resin insulation layer is formed. Production method.

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