JP2000059006A - Manufacture of printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid abnormal growth of an alloy layer comprising copper-nickel- phosphorus alloy by depositing copper-nickel-phophorus alloy, while suppressing the composition change in electroless plating solution. SOLUTION: In order to manufacture a printed wiring board 22 on which insulating resin layers 9, 18 are formed on conductor circuits 2, 14, 15 on a substrate 1, the conductor circuits 2, 14, 15 are provided on the substrate 1 so as to immerse the conductor circuits 2, 14, 15 in a plating solution containing a complexing agent, copper compound, nickel compound, hypophosphite and surfactant and then while fine bubbles are being produced, an alloy comprising copper, nickel and phosphorus is deposited on the surface of the conductor circuits 2, 14, 15 so that alloy roughened layers 8, 16 are formed on the surface of the conductor circuits 2, 14, 15 for providing insulating resin layers 9, 18 on the alloy roughened layers 8, 16.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a printed wiring board in which an insulating resin layer is provided on a conductive circuit on a substrate.

[0002]

2. Description of the Related Art As a method of manufacturing a build-up multilayer wiring board, a method disclosed in Japanese Patent Application Laid-Open No. 9-130050 is known.

In such a method, a needle-shaped alloy made of copper-nickel-phosphorus (Cu-Ni-P) is deposited on the surface of the conductor circuit by electroless plating in order to improve the adhesion between the conductor circuit and the insulating resin. Thus, a roughened alloy layer is formed. On the surface of the roughened alloy layer, an interlayer insulating resin is applied, exposed,
After developing, a via hole opening for interlayer conduction is formed, and after UV curing and main curing, an interlayer insulating layer is formed. Further, the surface of the interlayer insulating layer is roughened, and a catalyst such as palladium is applied to the roughened surface to form a thin electroless plating film. Thereafter, a pattern is formed on the film by a dry film, the film is thickened by electrolytic plating, and the dry film is peeled off with an alkali and etched to form a conductor circuit. By repeating such an operation, a build-up multilayer wiring board can be obtained.

[0004] After depositing a roughened alloy layer made of a Cu-Ni-P alloy, the roughened alloy layer is subjected to a Cu-Sn substitution reaction to form a Sn layer. Can be improved in adhesion.

[0005] Such an alloy layer made of a Cu-Ni-P alloy can also be used when a solder resist layer as an insulating resin layer is formed on the surface of a conductive circuit.

In such a build-up multilayer wiring board, Cu
The alloy roughened layer made of -Ni-P is formed by immersing the conductor circuit in an electroless plating solution. Such an electroless plating solution is air-stirred in advance to make the solution composition, the dissolved oxygen concentration, and the like uniform, and in such a state, the conductor circuit is charged. The conductor circuit put into the electroless plating solution starts oscillating after a few minutes. The needle-like alloy made of Cu-Ni-P precipitates on the surface of the conductor circuit.

[0007] In order to obtain a roughened alloy layer, the air stirring of the electroless plating solution is completely stopped while the conductor circuit is being supplied.

[0008]

The composition of the plating solution and the concentration of dissolved oxygen, etc., in the electroless plating solution in which the stirring of the air is completely stopped are reduced due to the accumulation and retention of active hydrogen due to the precipitation of the Cu-Ni-P alloy. And the Cu—Ni—P alloy may precipitate abnormally. The alloy abnormally precipitated in this way connects the alloy layers on the conductor circuit, making it difficult to ensure insulation.

Therefore, at predetermined intervals, the air stirring of the electroless plating solution is restarted, and the plating solution is cooled. By performing such cooling of the plating solution for a longer time, active hydrogen can be desorbed,
Thereby, abnormal growth of the alloy layer can be suppressed.

However, in the cooling process, the conductor circuit is removed from the plating tank during the cooling for the above-described reason. Thus, processing such as cooling,
Loss of working time and Cu-N
Since it becomes complicated to control the precipitation amount of the i-P alloy, the productivity is significantly reduced.

An object of the present invention is to deposit a Cu—Ni—P alloy while suppressing a change in the composition of an electroless plating solution, and to prevent such abnormal growth of a roughened alloy layer.

[0012]

According to the present invention, in obtaining a printed wiring board having an interlayer insulating resin layer provided between conductive circuits on a substrate, the conductive circuits are provided on the substrate.
The conductor circuit, a complexing agent, a copper compound, a nickel compound,
While immersed in a plating solution containing hypophosphite and a surfactant, and generating fine bubbles in the plating solution,
An alloy consisting of copper, nickel and phosphorus is deposited on the surface of the conductor circuit, and an alloy layer is formed on the surface of the conductor circuit,
The present invention relates to a method for manufacturing a printed wiring board, wherein the insulating resin layer is provided on the alloy layer.

The present inventors have studied the precipitation phenomenon of a Cu—Ni—P alloy in order to prevent abnormal growth of the alloy layer. As a result, during the precipitation of the Cu-Ni-P alloy,
The inventors have found out that abnormal growth of the alloy layer can be prevented by generating fine bubbles in the electroless plating solution, and completed the present invention.

The present inventor has found that, in particular, when depositing a needle-like alloy made of Cu—Ni—P on a copper conductor circuit that has been built up, the number of turns of the electroless plating solution increases, and
After reaching the turn, hydrogen gas accumulates in the plating solution and the initial reaction becomes violent, the needle-like alloy consisting of Cu-Ni-P extends abnormally between the alloy layers, and the needle-like alloy connects the conductor circuits. I figured out what to do.

The present inventor has studied based on this finding. As a result, when forming an alloy layer made of a Cu-Ni-P alloy on the surface of a conductive circuit, fine bubbles are continuously emitted into the electroless plating solution. The present inventors have found out that the accumulation of hydrogen gas accompanying the precipitation of Cu-Ni-P alloy is suppressed, and have reached the present invention.

According to the present invention, by causing the Cu—Ni—P alloy to precipitate while generating fine bubbles in the electroless plating solution, abnormal precipitation of the Cu—Ni—P alloy can be suppressed. The abnormal growth of the alloy layer formed on the circuit can be prevented.

Further, according to the present invention, the Cu—Ni—P alloy does not abnormally precipitate even with the electroless plating solution having the advanced number of turns, so that the life of the plating aqueous solution is extended,
A multilayer printed wiring board having excellent productivity and cost can be manufactured.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
The fine bubbles according to the present invention are generated in the plating solution when the conductor circuit is charged in the plating solution. Such fine bubbles can expel the hydrogen gas accompanying the precipitation of the Cu-Ni-P alloy from the plating solution and increase the dissolved oxygen concentration of the plating solution.

According to the present invention, even when a roughened layer of Cu—Ni—P alloy is deposited on a conductor circuit, the accumulation of by-products in the electroless plating solution is suppressed in this manner, whereby the composition of the plating solution is reduced. Can be maintained in a favorable state, so that abnormal growth of the roughened alloy layer can be prevented.

JP-A-63-31983 discloses that an oxygen-containing gas having a bubble diameter of 0.5 mm or less is dispersed in an electroless copper plating solution so that the concentration of dissolved oxygen in the plating solution is locally uniform. And a method of keeping it constant is known. However, such an electroless copper plating method is a technique for forming a fine and high-density wiring pattern by copper plating, and a roughened alloy layer made of a Cu-Ni-P alloy is formed on the surface of a conductor circuit as in the present invention. It is not a technique for precipitating.

In the method described in Japanese Patent Application Laid-Open No. 63-31983, a fine and high-density wiring pattern is formed by copper plating.
-The alloy roughened layer made of the P-needle alloy cannot be formed on the surface of the conductor circuit. Therefore, JP-A-63-31
The present invention cannot be easily conceived from the method described in Japanese Patent No. 2983.

The fine bubbles according to the present invention can be generated in the electroless plating solution so as not to directly contact the surface of the conductor circuit, and to prevent the catalyst nuclei applied to the surface of the conductor circuit from dropping. It can also be done.

The fine bubbles are 0.1 to 3.0 mm
It preferably has an average diameter of Average diameter is 0.1m
Bubbles less than m are less likely to expel by-products such as hydrogen gas generated during the deposition of the Cu-Ni-P alloy from the plating solution. Bubbles having an average diameter of more than 3.0 mm may drop catalyst nuclei applied to the surface of the conductor circuit. More preferably, such fine bubbles have an average diameter of 0.1-0.5 mm.

Such air bubbles are converted to 5 to 1 at 1 atm.
Preferably, it is generated at a flow rate of 00 L / min. At a flow rate less than 5 L / min, it is difficult to remove by-products such as hydrogen gas from the plating solution. At a flow rate exceeding 100 L / min,
The catalyst core applied to the surface of the conductor circuit may be dropped.
The optimal condition is a flow rate of 30 L / min.

The piping for generating such fine bubbles can be provided at at least one position in the bottom of the plating tank, the side wall of the plating tank, and the accompanying overflow. At any position, it is preferable to perform bubbling through an air diffuser or the like provided with a fine-diameter hole so that air bubbles do not directly contact the conductor circuit.

Such fine bubbles can be formed from at least one gas selected from the group consisting of air, oxygen, nitrogen and a rare gas. In order to increase the dissolved oxygen concentration in the plating solution, it is preferable to use a gas containing oxygen.

The electroless plating solution used in the present invention is air-stirred in advance to make the plating solution composition, dissolved oxygen concentration and the like uniform. For such air stirring, main bubbling having an average bubble diameter of more than 3.0 mm can be used.
The conductor circuit according to the present invention is put into the electroless plating solution that has been made uniform in advance in this way.

The main bubbling can be generated from the entire plating tank at a flow rate of 20 to 200 L / min in terms of one atmosphere. The piping for discharging such bubbles can be provided at at least one of the bottom of the plating tank, the side wall of the plating tank, and the accompanying overflow. Such main bubbling is completely stopped while the conductor circuit is immersed in the plating bath.

The fine bubbles according to the present invention can be generated as sub fine bubbling of the main bubbling. Such fine bubbling can be used together with the main bubbling for conditioning the electroless plating solution before introducing the conductor circuit.

Further, since the reduction of dissolved oxygen in the plating solution affects the deposition of the plating alloy, when the conductor circuit is not put into the plating tank, bubbling is performed from both the main bubbling and the sub-fine bubbling. be able to. Thereby, oxygen is supplied to the plating solution. At this time, the larger the supply amount of oxygen, the better. However, there is no problem even if the flow rate of the main bubbling is 20 to 200 L / min.

However, when the conductor circuit is put into the plating bath, the initial reaction may be stopped by bubbling, so that bubbling must be suppressed. Therefore, the main bubbling is stopped, and bubbles are generated only by the sub fine bubbling.

In the present invention, the roughened alloy layer made of Cu-Ni-P is thus formed on the conductor circuit. Such a roughened alloy layer is not limited to the case of depositing a needle-shaped alloy made of Cu-Ni-P, but may be formed by depositing a roughened alloy layer of various shapes on a conductor circuit to thereby achieve close contact with the insulating resin layer. Can be planned.

Further, the method of the present invention is characterized in that an alloy layer made of a needle-shaped alloy, a porous alloy layer, an alloy layer obtained by combining these shapes, and an alloy layer made of a needle-shaped alloy and a porous alloy layer are formed. It can also be used when forming a roughened alloy layer made of Cu-Ni-P such as a mixed alloy layer on a conductor circuit.

The porous alloy layer refers to an alloy layer in which the conductor circuit surface is covered with an alloy layer made of Cu-Ni-P, and micropores are formed on the surface of the alloy layer.
The micropores have a diameter of 0.1-10 μm and a number of 3,000,
It is preferably formed in the range of 000 to 300,000,000 / cm ² .

The composition of the alloy layer made of a Cu--Ni--P alloy is preferably such that the proportions of copper, nickel and phosphorus are 90 to 96% by weight, 1 to 5% by weight, and 0.5 to 2% by weight, respectively. This is because, at these composition ratios, the precipitated alloy shows a needle shape.

The alloy layer according to the present invention is covered with an insulating resin layer, such as an interlayer insulating resin layer or a solder resist layer, for insulating between conductor circuits. At this time, such an alloy layer is 1 to 5
It should have a thickness of μm. If the thickness is too large, the alloy layer itself is damaged or easily peeled off, which leads to a decrease in productivity and an increase in cost.If the thickness is too small, the adhesion to an insulating resin such as an interlayer insulating resin layer or a solder resist layer is reduced. It is because it falls.

After depositing a roughened alloy layer made of a Cu—Ni—P alloy by the method according to the present invention,
By performing a u-Sn substitution reaction to form a Sn layer,
Adhesion between the conductor circuit and the interlayer insulating resin can be ensured.

The alloy layer made of such a Cu—Ni—P alloy can be used for forming a solder resist layer on the surface of a conductor circuit.

The solder resist layer covers the conductor circuit formed on the insulating layer and has an opening for mounting an electronic component. In such a solder resist layer, a reinforcing layer made of a resin containing a thermoplastic resin may be formed thereon. Such a high-toughness reinforcing layer can suppress the occurrence of cracks in the solder resist layer, prevent the adhesion of dust, which is considered to be one of the causes of the cracks, and suppress the occurrence of cracks.

The reinforcing layer is desirably made of at least one of a thermosetting resin and a thermoplastic resin and a photosensitive resin and a thermoplastic resin. This is because the former has high heat resistance, and the latter can form a reinforcing layer by photolithography.

As the thermosetting resin, epoxy resin, phenol resin, polyimide resin and the like can be used. In the case of photosensitizing such a thermosetting resin, methacrylic acid, acrylic acid, or the like is subjected to an acrylate reaction with a thermosetting group. In particular, an acrylate of an epoxy resin is most suitable. As the epoxy resin, a novolak type epoxy resin such as a phenol novolak type or a cresol novolak type, or an alicyclic epoxy resin modified with dicyclopentadiene can be used.

As the thermoplastic resin, polyether sulfone (PES), polysulfone (PSF), polyphenylene sulfone (PPS), polyphenylene sulfide (PPES), polyphenyl ether (PP
E), polyetherimide (PI) and the like can be used.

The reinforcing layer is preferably formed of at least one of a composite of an epoxy resin and a polyethersulfone and a composite of an epoxy resin acrylate and a polyethersulfone among such resin combinations. preferable.

The mixing ratio of the thermosetting resin (photosensitive resin) and the thermoplastic resin is preferably thermosetting resin (photosensitive resin) / thermoplastic resin = 95/5 to 50/50. This is because a high toughness value can be secured without impairing the heat resistance.

Further, such a reinforcing layer may contain heat-resistant resin particles. Such heat-resistant resin particles can be formed from an amino resin (melamine resin, urea resin, guanamine resin, and the like), an epoxy resin, and the like. Further, it is desirable that the heat resistant resin particles have an average particle diameter of 0.1 to 1.0 μm. This is because the range does not decrease the toughness value of the reinforcing layer.

The mixing weight ratio of the heat-resistant resin particles is preferably 5 to 50% by weight, more preferably 10 to 40% by weight, based on the solid content of the heat-resistant resin matrix. This is because, while imparting an appropriate viscosity, the progress of cracks generated in the reinforcing layer can be suppressed.

The reinforcing layer thus formed is desirably formed in a region of the solder resist layer where an opening for mounting electronic components is provided, that is, around the solder bump group. If a reinforcing layer is formed in a group of solder bumps, mounting failure may occur when mounting an IC chip.
The thickness of the reinforcing layer is desirably 5 to 50 μm. This is because cracks can be suppressed by minimizing the increase in the thickness of the substrate.

Various resins can be used for the solder resist layer, for example, bisphenol A type epoxy resin, bisphenol A type epoxy resin acrylate,
A novolak epoxy resin or a resin obtained by curing an acrylate of a novolak epoxy resin with an amine curing agent, an imidazole curing agent, or the like can be used.

In particular, when an opening is provided in the solder resist layer to form a solder bump, the solder resist layer is formed from a novolak-type epoxy resin or a material containing an acrylate of a novolak-type epoxy resin and an imidazole curing agent. Is preferred.

The solder resist layer having such a structure is
There is an advantage that migration of lead (phenomenon in which lead ions diffuse in the solder resist layer) is small. Moreover, this solder resist layer is a resin layer obtained by curing an acrylate of a novolak type epoxy resin with an imidazole curing agent, has excellent heat resistance and alkali resistance, does not deteriorate even at a temperature at which solder is melted (around 200 ° C.), and does not deteriorate. It is not decomposed by a strongly basic plating solution such as plating or gold plating.

However, since such a solder resist layer is formed of a resin having a rigid skeleton, peeling is likely to occur. The above-described reinforcing layer is advantageous in that the peeling of the solder resist layer can be prevented.

Here, as the acrylate of the novolak type epoxy resin, an epoxy resin obtained by reacting glycidyl ether of phenol novolak or cresol novolak with acrylic acid, methacrylic acid or the like can be used.

The imidazole curing agent is desirably liquid at 25 ° C. This is because a liquid can be uniformly mixed. Examples of such a liquid imidazole curing agent include 1-benzyl-2-methylimidazole (product name: 1B2MZ) and 1-cyanoethyl-2-ethyl-4-methylimidazole (product name: 2E4M).
Z-CN), 4-methyl-2-ethylimidazole (product name: 2E4M
Z) can be used.

It is desirable to use a glycol ether-based solvent as the solvent in the solder resist composition containing these components. The solder resist layer using such a composition does not generate free oxygen and does not oxidize the copper pad surface. It is also less harmful to the human body.

As the glycol ether solvent, those having the following structural formula, particularly preferably at least one selected from diethylene glycol dimethyl ether (DMDG) and triethylene glycol dimethyl ether (DMTG) can be used. This is because these solvents can completely dissolve benzophenone and Michler's ketone as reaction initiators by heating at about 30 to 50 ° C. CH ₃ O— (CH ₂ CH ₂ O) _n —CH ₃ (n = 1 to
5) The glycol ether solvent is preferably added in an amount of 10 to 40% by weight based on the total weight of the solder resist composition.

The addition amount of the imidazole curing agent is preferably 1 to 10% by weight based on the total solid content of the solder resist composition. The reason is that if the amount added is within this range, uniform mixing is easy.

In addition to the above-described compositions for solder resists, various defoaming agents and leveling agents, thermosetting resins for improving heat resistance and base resistance and imparting flexibility, and improving resolution can be used. For this purpose, a photosensitive monomer or the like can be added.

For example, as the leveling agent, one composed of a polymer of an acrylate ester is preferable. The initiator is preferably Irgacure I907 manufactured by Ciba-Geigy, and the photosensitizer is preferably DETX-S manufactured by Nippon Kayaku.

Further, a dye or pigment may be added to the solder resist composition. This is because the wiring pattern can be hidden. It is desirable to use phthalocyanine green as this dye.

As the thermosetting resin as an additional component,
A bisphenol-type epoxy resin can be used.
This bisphenol type epoxy resin includes a bisphenol A type epoxy resin and a bisphenol F type epoxy resin, and when importance is attached to base resistance, the former is required to reduce viscosity (when importance is attached to coating properties). The latter is better.

As the photosensitive monomer as an additional component, a polyvalent acrylic monomer can be used. This is because polyacrylic monomers improve resolution. For example, polyacrylic monomers such as Nippon Kayaku's DPE-6A and Kyoeisha Chemical's R-604 are desirable.

The solder resist composition thus prepared preferably has a viscosity of 0.5 to 10 Pa · s at 25 ° C., more preferably 1 to 10 Pa · s. This is because application with a roll coater is easy.

The thickness of the formed solder resist layer is as follows:
5 to 40 μm is preferred. If it is too thin, it will not function as a solder dam, and if it is too thick, it will be difficult to open, and it will come into contact with the solder body and cause cracks to occur in the solder body.

In the present invention, the via hole functioning as a solder pad can adopt either a form in which a part thereof is exposed by a solder resist layer or a form in which the whole is exposed. In the former case, cracking of the resin insulating layer at the boundary between the conductor pad or the via hole can be prevented, and in the latter case, the allowable range of the positional deviation of the opening can be increased.

In the case of a build-up multilayer wiring board, there are a plurality of conductor circuits. Therefore, in the present invention, the Cu—Ni—P according to the present invention is provided on at least one type of conductive circuit surface.
And a roughened surface other than the Cu-Ni-P alloy can be formed on the surface of the other conductor circuit. Such another roughened surface is desirably a roughened surface formed by etching, polishing, oxidation, oxidation-reduction treatment, or the like of the copper conductor circuit, or a roughened surface formed by a plating film.

The oxidation treatment is desirably performed with a solution of an oxidizing agent such as sodium chlorite, sodium hydroxide, sodium phosphate and the like. After the oxidation treatment, the oxidation-reduction treatment is performed by dipping in a solution such as sodium hydroxide and sodium borohydride.

The roughened surface preferably has a thickness of 1 to 5 μm. If the thickness is too large, the alloy layer itself is easily damaged and peeled off, and if the thickness is too small, the adhesion to the insulating resin layer is reduced.

It is to be noted that even such a roughened surface is desirably an alloy roughened layer made of the Cu—Ni—P alloy according to the present invention.

In the present invention, the surface of the alloy layer made of the Cu—Ni—P alloy is coated with an interlayer insulating resin layer.
Such an interlayer insulating resin layer is desirably formed using an adhesive for electroless plating. Such an adhesive for electroless plating is optimally one in which cured heat-resistant resin particles soluble in an acid or an oxidizing agent are dispersed in an uncured heat-resistant resin hardly soluble in an acid or an oxidizing agent. is there.

By treating the adhesive for electroless plating with an acid or an oxidizing agent, the heat-resistant resin particles are dissolved and removed, and a roughened surface composed of an octopus-shaped anchor can be formed on the surface. .

The cured heat-resistant resin particles include, in particular, heat-resistant resin powder having an average particle size of 10 μm or less, aggregated particles obtained by aggregating heat-resistant resin powder having an average particle size of 2 μm or less, and average particle size. A mixture of a heat-resistant resin powder having a mean particle size of 2 to 10 μm and a heat-resistant resin powder having a mean particle size of less than 2 μm. Particles obtained by adhering at least one kind of powder selected from the group consisting of a conductive resin powder and an inorganic powder, having an average particle size of 0.1 to 0.8 μm
A mixture of a heat-resistant powder resin powder having a mean particle size of more than 0.8 μm and a heat-resistant resin powder having a mean particle size of less than 2 μm, and a heat-resistant powder resin powder having a mean particle size of 0.1 to 1.0 μm It is desirable to use at least one kind of heat-resistant resin particles selected from the following. This is because they can form more complex anchors.

The depth of the roughened surface thus formed is preferably Rmax = 0.01 to 20 μm. This is to ensure adhesion. In particular, in the semi-additive method, 0.
1-5 μm is preferred. This is because the electroless plating film can be removed while ensuring adhesion.

[0073]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments and comparative examples with reference to the drawings. FIG. 1 is a longitudinal sectional view of an example of a wiring board according to the present invention. Figures 2 and 3
It is a longitudinal section of an example of a plating tank concerning the present invention. Example In this example, the number of turns was 0, 0.5, or
Using any one of the electroless plating solutions of 1.0, 1.5 and 2.0, five types of build-up wiring boards as shown in FIG. 1 were produced.

A. Raw material group for preparing adhesive for electroless plating
Composition ( adhesive for upper layer) [Resin composition] 35 parts by weight of a resin solution prepared by dissolving 25% acrylate of cresol novolak type epoxy resin (manufactured by Nippon Kayaku, molecular weight 2500) in DMDG at a concentration of 80% by weight And a photosensitive monomer (Aronix M315, manufactured by Toa Gosei)
) 3.15 parts by weight and 0.5 of defoamer (manufactured by San Nopco, S-65)
Parts by weight and 3.6 parts by weight of NMP were obtained by stirring and mixing.

[Resin Composition] Polyethersulfone (PES) 12 parts by weight, epoxy resin particles (manufactured by Sanyo Chemical Industries, polymer pole) having an average particle size of 1.0 μm 7.2 parts by weight, and having an average particle size of 0.5 μm Was mixed with 3.09 parts by weight of NMP, 30 parts by weight of NMP was further added, and the mixture was stirred and mixed with a bead mill.

[Curing Agent Composition] 2 parts by weight of an imidazole curing agent (2E4MZ-CN, manufactured by Shikoku Chemicals), 2 parts by weight of a photoinitiator (Irgacure I-907, manufactured by Ciba Geigy), and a photosensitizer (Nippon Kagaku) Pharmaceutical, DETX-S) 0.2 parts by weight and NMP
1.5 parts by weight were obtained by stirring and mixing.

B. Raw material composition for preparing interlayer resin insulation agent
(Lower layer adhesive) [Resin composition] 35 parts by weight of a resin solution in which 25% acrylate of cresol novolac type epoxy resin (manufactured by Nippon Kayaku, molecular weight 2500) was dissolved in DMDG at a concentration of 80% by weight, Photosensitive monomer (Toa Gosei Co., Aronix M315
) 4 parts by weight and 0.5 of defoamer (manufactured by San Nopco, S-65)
Parts by weight and 3.6 parts by weight of NMP were obtained by stirring and mixing.

[Resin Composition] Polyethersulfone (PES) having 12 parts by weight and epoxy resin particles (manufactured by Sanyo Chemical Industries, polymer pole) having an average particle diameter of 0.5 μm 14.49
After that, 30 parts by weight of NMP was further added, and the mixture was stirred and mixed with a bead mill to obtain.

[Curing Agent Composition] 2 parts by weight of an imidazole curing agent (2E4MZ-CN, manufactured by Shikoku Chemicals), 2 parts by weight of a photoinitiator (Irgacure I-907, manufactured by Ciba Geigy), and a photosensitizer (Nippon Kagaku) Yakuhin, DETX-S) 0.2 parts by weight and NMP1.
And 5 parts by weight.

C. Raw material composition for preparing resin filler [resin composition] 100 parts by weight of bisphenol F type epoxy monomer (manufactured by Yuka Shell, molecular weight 310, YL983U),
SiO ₂ spherical particles with an average particle diameter of 1.6 μm coated with a silane coupling agent (Admatech, CRS
1101-CE, where the maximum particle size is not more than the thickness (15 μm) of the inner copper pattern described later) 170 parts by weight;
By stirring and mixing 1.5 parts by weight of a leveling agent (manufactured by San Nopco, Perenol S4), the viscosity of the mixture is reduced.
It was obtained by adjusting to 45,000-49,000 cps at 23 ± 1 ° C.

[Curing Agent Composition] 6.5 parts by weight of imidazole curing agent (2E4MZ-CN, manufactured by Shikoku Chemicals).

D. Production of Printed Wiring Board (1) A copper-clad laminate in which 18 μm copper foil is laminated on both sides of a substrate 1 made of glass epoxy resin or BT (bismaleimide triazine) resin having a thickness of 1 mm as shown in FIG. Used as starting material. First, the copper clad laminate was drilled, subjected to electroless plating, and etched in a pattern to form an inner copper pattern (conductor circuit) 2 and a through hole 3 on both surfaces of the substrate.

(2) The substrate on which the conductor circuit 2 and the through hole 3 were formed was washed with water and dried, and then used as an oxidation bath (blackening bath) as NaOH (10 g / L), NaClO ₂ (40 g / L), ₃ P
O ₄ (6 g / L), NaOH (10 g / L), Na
Roughened surfaces 4 and 5 were provided on the surfaces of the conductor circuit 2 and the through hole 3 by oxidation-reduction treatment using BH ₄ (6 g / L).

(3) The raw material composition for preparing the resin filler C was mixed and kneaded to obtain a resin filler. (4) The resin filler obtained in the above (3) is applied to both surfaces of the substrate using a roll coater within 24 hours after preparation, thereby filling the space between the conductor circuits 2 and the inside of the through holes 3 to obtain a resin filler.
After drying at 20 ° C. for 20 minutes, the other side was filled with a resin filler between the conductor circuits 2 and into the through holes 3 in the same manner, and dried by heating at 70 ° C. for 20 minutes.

(5) One surface of the substrate after the treatment of the above (4) is subjected to belt sander polishing using # 600 belt polishing paper (manufactured by Sankyo Rikagaku Co., Ltd.) to form the surface of the conductor circuit 2 and the land of the through hole 3. Polishing was performed so that no resin filler remained on the surface, and then buffing was performed to remove scratches due to the belt sander polishing. This series of polishing was similarly performed on the other surface of the substrate.

Next, a heat treatment was performed at 100 ° C. for 1 hour, at 120 ° C. for 3 hours, at 150 ° C. for 1 hour, and at 180 ° C. for 7 hours to cure the resin filler. In this manner, the surface layer portion of the resin filler filled in the through holes and the roughened surface on the upper surface of the conductor circuit 2 are removed, and both surfaces of the substrate are smoothed.
Is firmly adhered to the side surface of the conductor circuit 2 via the roughened surface 4, and the wiring board is obtained in which the resin layer 7 is firmly adhered to the inner wall surface of the through hole 3 via the roughened surface 5. . That is, by this step, the surface of the resin layer and the surface of the conductor circuit become the same plane.

(6) The printed wiring board on which the conductor circuit 2 was formed in this way was degreased with alkali and soft-etched. Next, the catalyst was treated with a catalyst solution comprising palladium chloride and an organic acid to provide a Pd catalyst, and the catalyst was activated. On the other hand, copper sulfate 3.2 × 10 ⁻² mol / L, nickel sulfate 3.9 × 10 ⁻³ mol / L, sodium citrate 5.4 × 10 ⁻² mol / L, sodium hypophosphite 3. 3
An electroless plating solution composed of × 10 ^-1 mol / L, a surfactant (Surfir 465, manufactured by Nissin Chemical Industry) 1.1 × 10 ^-4 mol / L, and PH = 9 was prepared. The main bubbling using air (150 L / min) and the sub-fine bubbling (flow rate 30 L / min) were previously stirred.

The conductor circuit 2 was prepared in this manner.
It was immersed in an electroless plating solution having any of 0, 0.5, 1.0, 1.5 and 2.0 turns. At this time, the main bubbling of the electroless plating solution was stopped. As shown in FIG. 2, the sub bubbling (flow rate 30 L / min) made of fine bubbles 23 is plated through the air diffuser 25 on the bottom surface of the plating tank 24 so as not to contact the conductor circuit 2 of the printed wiring board. Generated continuously in liquid 26.

The fine bubbles 23 have a longer residence time as much as possible, and gradually rise in the plating solution 26 in the direction A. The air diffuser 25 was provided with a hole having a diameter suitable for generating fine bubbles 23, and the plating solution 26 was circulated in the B and C directions toward overflows 27 attached to both sides of the plating tank 24.

One minute after the immersion, the printed wiring board was vibrated and rocked at a rate of once per 4 seconds, so that the needle-like alloy made of Cu-Ni-P was applied to the surfaces of the lands of the conductor circuit 2 and the through holes 3. An alloy layer 8 was provided by coating. After taking out the wiring board from the plating tank 24, as shown in FIG.
The main bubbling 28 was immediately restarted from the air diffuser 29 provided with a large hole.

Thereafter, tin borofluoride 0.1 mol / L, thiourea 1.0 mol / L, temperature 35 ° C., PH =
A Cu—Sn substitution reaction was performed under the conditions of 1.2, and a 0.3 μm thick Sn layer was provided on the surface of the alloy layer 8 (not shown).

(7) The raw material composition for preparing the interlayer resin insulating agent of B was stirred and mixed, and the viscosity was adjusted to 1.5 Pa · s to obtain an interlayer resin insulating agent (for lower layer). Next, the raw material composition for preparing the adhesive for electroless plating of A was stirred and mixed, and the viscosity was adjusted to 7 Pa · s to obtain an adhesive solution for electroless plating (for the upper layer).

(8) The interlayer resin insulating material (for lower layer) having a viscosity of 1.5 Pa · s obtained in the above (7) was applied to both surfaces of the substrate of the above (6) by a roll coater within 24 hours after preparation. In a horizontal position
Leave for 20 minutes, then dry at 60 ° C for 30 minutes (pre-bake)
Then, apply the photosensitive adhesive solution (for upper layer) having a viscosity of 7 Pa · s obtained in the above (7) within 24 hours after preparation, leave it in a horizontal state for 20 minutes, (Prebaking) for 30 minutes to form an interlayer resin insulating layer 9 having a thickness of 35 μm.

(9) A photomask film on which a black circle of 85 μmφ is printed is brought into close contact with both surfaces of the substrate on which the interlayer resin insulating layer 9 is formed in the above (8), and is supplied with an ultrahigh pressure mercury lamp at 500 mJ / cm2.
Exposure was in cm ² . This was spray-developed with a DMTG solution.
Exposed with ^2, 1 hour at 100 ° C., 1 hour, then at 120 ° C.
By performing heat treatment (post-baking) at 150 ° C. for 3 hours, an opening 10 (opening for forming a via hole) of 85 μmφ excellent in dimensional accuracy corresponding to a photomask film was opened in the interlayer resin insulating layer 9. Note that the tin plating layer was partially exposed in the opening 10 serving as a via hole.

(10) The substrate in which the openings 10 are formed is immersed in chromic acid for 19 minutes to dissolve and remove the epoxy resin particles present on the surface of the interlayer resin insulating layer 9, thereby forming the interlayer resin insulating layer 9. The surface was made to be a roughened surface 11, which was then immersed in a neutralizing solution (manufactured by Shipley) and then washed with water.

Further, by applying a palladium catalyst (manufactured by Atotech) to the surface of the substrate which has been subjected to the surface roughening treatment (roughening depth: 6 μm), the surface of the interlayer resin insulating layer 9 and the inside of the via hole opening 10 are formed. A catalyst core was attached to the wall.

(11) The substrate was immersed in an electroless copper plating aqueous solution having the composition shown below, and a thickness of 0.6 μm
m of electroless copper plating film was formed. [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 PEG 0.1 g / L [Electroless plating conditions] 70 ° C 30 minutes at liquid temperature

(12) A commercially available photosensitive dry film is stuck on the electroless copper plating film formed in the above (11), a mask is placed thereon, and exposure is performed at 100 mJ / cm ² , followed by exposure to 0.8% sodium carbonate. After developing, a plating resist having a thickness of 15 μm was provided.

(13) Next, electrolytic copper plating was applied to the non-resist-formed portions under the following conditions to form an electrolytic copper plating film having a thickness of 15 μm. [Electroplating aqueous solution] Sulfuric acid 180 g / L Copper sulfate 80 g / L Additive (captoside GL, manufactured by Atotech Japan) 1 mL / L [Electroplating conditions] Current density 1 A / dm ² hours 30 minutes Temperature Room temperature

(14) After peeling off the plating resist with 5% KOH, the electroless plating film under the plating resist is dissolved and removed by etching with a mixed solution of sulfuric acid and hydrogen peroxide, and the electroless copper plating film is removed. A conductor circuit 14 (including the via hole 15) having a thickness of 16 μm and including the electrode 12 and the electrolytic copper plating film 13 was formed.

(15) The same processing as in (6) is performed, and Cu-Ni
A roughened alloy layer 16 made of -P was formed, and the surface thereof was further substituted with Sn. (16) Although not shown, by repeating the above steps (7) to (15), a conductor circuit of an upper layer was further formed, and a multilayer wiring board was obtained. However, Sn substitution was not performed.

(17) On the other hand, 60% by weight dissolved in DMDG
Cresol novolak epoxy resin (Nippon Kayaku)
46.67 g of a photosensitizing oligomer (molecular weight 4000) in which 50% of the epoxy groups of the above were acrylated, and 15.0 g of an 80 wt% bisphenol A type epoxy resin (Epicoat 1001 manufactured by Yuka Shell) dissolved in methyl ethyl ketone, 1.6 g of imidazole curing agent (2E4MZ-CN, manufactured by Shikoku Chemicals) and polyacrylic monomer (Nippon Kayaku,
R604), 1.5 g of a polyvalent acrylic monomer (manufactured by Kyoeisha Chemical Co., DPE6A) and 0.71 g of a dispersant defoaming agent (manufactured by San Nopco, S-65). 2 g of benzophenone (manufactured by Kanto Kagaku) as a photoinitiator and 0.2 g of Michler's ketone (manufactured by Kanto Kagaku) as a photosensitizer were added, and the viscosity was adjusted to 2.0 Pa · s at 25 ° C. for a solder resist composition. I got something. The viscosity was measured with a B-type viscometer (Tokyo Keiki, DVL-B type) using rotor No. 4 at 60 rpm and rotor No. 3 at 6 rpm.

(18) The solder resist composition was applied to both sides of the multilayer wiring board obtained in the above (16) in a thickness of 20 μm. Next, after performing a drying treatment at 70 ° C. for 20 minutes and at 70 ° C. for 30 minutes, a 5 mm-thick photomask film on which a circular pattern (mask pattern) is drawn is placed in close contact with the substrate, and 1000 mJ / cm ^2. And subjected to DMTG development processing. And 1 hour at 80 ° C, 1 hour at 100 ° C,
Heat treatment at 20 ° C. for 1 hour and 150 ° C. for 3 hours to form a solder resist layer 18 (opening diameter 200 μm) with solder pad portions 17 (including via holes and their land portions) (opening diameter 200 μm) (thickness 20 μm). did.

(19) Next, a solder resist layer 18 is formed.
The substrate was nickel chloride 2.31 × 10 ^-1Mol / L,
Sodium salt 2.84 × 10^-1Mol / L, sodium citrate
1.55 × 10^-1Electroless nickel of pH = 5 consisting of mol / L
Dipped in a plating solution for 20 minutes, and a 5 μm thick
The nickel plating layer 19 was formed. In addition, the board is
Potassium gold anhydride 7.61 × 10^-3Mol / L, ammonium chloride
1.87 × 10^-1Mol / L, sodium citrate 1.16 × 10^-1
Mol / L, sodium hypophosphite 1.70 × 10^-1Mol / L
Immersion for 23 seconds at 93 ° C
0.03μm thick gold plating on the nickel plating layer 19
Layer 20 was formed.

(20) A solder paste is printed on the opening 17 of the solder resist layer 18 and reflowed at 200 ° C. to form a solder bump 21 (solder body), and the printed wiring board having the solder bump is formed. 22 were produced.

Comparative Example Basically the same as the example, but while the conductor circuit was immersed in the plating solution, sub-micro bubbling was also stopped.

As described above, for each of the printed wiring boards manufactured in Examples and Comparative Examples, Cu-Ni
The thickness and shape of the coating layer of the needle-shaped alloy composed of -P and the rate of occurrence of connection failure between the conductor circuits were compared, and the presence or absence of peeling of the interlayer resin insulating layer was confirmed. Table 1 shows the evaluation results of this example and the comparative example.

[0108]

[Table 1]

As shown in Table 1, in the example, even if the electroless plating solution was used up to 2.0 turns, the electroless plating solution was equivalent to the case of 0 turns, and there was no particular problem. In the comparative example, the connection of the conductor circuit was turned from the 0.5th turn, and the harrowing was 1.5 times.
Occurs from the turn.

[0110]

According to the present invention, the abnormal precipitation of Cu-Ni-P alloy can be suppressed by depositing Cu-Ni-P alloy while generating fine bubbles in the electroless plating solution. In addition, abnormal growth of the alloy layer formed on the conductor circuit can be prevented.

Further, according to the present invention, the Cu—Ni—P alloy does not abnormally precipitate even with the electroless plating solution having the advanced number of turns, so that the life of the plating aqueous solution is extended,
A multilayer printed wiring board having excellent productivity and cost can be manufactured.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an example of a printed wiring board according to the present invention.

FIG. 2 is a longitudinal sectional view of an example of a plating tank according to the present invention.

FIG. 3 is a longitudinal sectional view of an example of a plating tank according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2,14 Conductor circuit 3 Through hole 4,5 Roughened surface 6,7 Resin layer 8,16 Alloy layer 9 Interlayer insulating resin layer 10 Opening 11 Roughened surface 12 Electroless copper plating film 13 Electrolytic copper plating film 15 Via Hole 17 Solder pad portion 18 Solder resist layer 19 Nickel plating layer 20 Gold plating layer 21 Solder bump 22 Printed wiring board 23 Fine bubbles 24 Plating tank 25, 29 Air diffuser 26 Plating solution 27 Overflow 28 Main bubbling

Continued on front page F term (reference) 5E343 AA12 BB34 BB53 CC78 DD33 FF17 GG20 5E346 CC08 CC32 DD23 FF13 GG17 HH33

Claims (5)

[Claims] In order to obtain a printed wiring board in which an insulating resin layer is provided on a conductive circuit on a substrate, the conductive circuit is provided on the substrate, and the conductive circuit is provided with a complexing agent, a copper compound, and nickel. An alloy composed of copper, nickel and phosphorus is deposited on the surface of the conductor circuit while immersing in a plating solution containing a compound, hypophosphite and a surfactant, and generating fine bubbles in the plating solution. Forming an alloy layer on the surface of the conductive circuit, and providing the insulating resin layer on the alloy layer. 2. The method for manufacturing a printed wiring board according to claim 1, wherein said fine bubbles are made of at least one kind of gas selected from the group consisting of air, oxygen, nitrogen and a rare gas. 3. The method according to claim 1, wherein the fine bubbles have a diameter of 0.1 to 3.0 mm.
3. The method for producing a printed wiring board according to claim 1, wherein said fine bubbles are generated at a flow rate of 5 to 100 L / min in terms of 1 atm. Method. 4. The print according to claim 1, wherein the fine bubbles are generated from at least one of a bottom of the plating tank, a side wall of the plating tank, and an associated overflow. Manufacturing method of wiring board. 5. When the conductor circuit is not immersed,
Having an average diameter of greater than 3.0 mm, and generating bubbles and fine bubbles at a flow rate of 20 to 200 L / min in terms of one atmosphere in the plating solution at the same time, A method for manufacturing a printed wiring board according to claim 1.