JP2000114719A - Manufacture of multilayer printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid the undeposition and abnormal deposition of plating when plating of acicular alloy composed of Cu-Ni-P is applied to a conductor circuit. SOLUTION: An interlayer resin insulating layer and a new conductor circuit are successively layered on a board on which a conductor circuit is formed to obtain a multilayer board. The board on which the conductor circuit is formed is dipped into solution containing copper ions, nickel ions, complexing agent, hypophosphite ions and surface-active agent. The dissolved oxygen concentration of the solution is adjusted to be 1.5-2.5 ppm to form a roughed layer made of Cu-Ni-P on the conductor circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a multilayer printed wiring board, and more particularly to a method for forming a roughened plating Cu--Ni.
The present invention relates to a method for manufacturing a multilayer printed wiring board capable of preventing unprecipitated or abnormal deposition of a P alloy plating layer.

[0002]

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 due to a demand for higher density of the multilayer wiring board. In this multilayer build-up wiring board, a wiring layer made of copper or the like and an interlayer resin insulation layer are alternately laminated on a resin substrate reinforced with a glass cloth of about 100 to 1000 μm called a core, and the core is sandwiched therebetween. 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.

When manufacturing this multilayer build-up wiring board, for example, a method disclosed in Japanese Patent Application Laid-Open No. 6-283860 is used. That is, first, Cu—Ni—P is formed on the surface of the inner conductor circuit formed on the substrate by electroless plating.
A roughened layer of a needle-shaped alloy is formed, and then an interlayer resin insulating layer is formed on the roughened layer, and then an opening for forming a via hole is provided in the interlayer resin insulating layer.

[0004] Thereafter, the substrate is subjected to a plating treatment to fill the openings with a conductor and form an outer conductor circuit on the interlayer resin insulating layer. Further, by repeating the formation of such a conductor circuit and the formation of the interlayer resin insulating layer, a multi-layer structure can be achieved.

According to the method disclosed in Japanese Patent Application Laid-Open No. 6-283860, in a multilayer build-up wiring board, the conductor is formed by a needle-like alloy made of Cu-Ni-P formed on a conductor circuit. Adhesion between the circuit and the interlayer resin insulating layer formed thereon can be ensured.

[0006]

When performing the needle-like alloy plating process of Cu-Ni-P, the substrate on which the conductor circuit is formed is treated with copper ions, nickel ions, a complexing agent,
It is immersed in a plating solution containing hypophosphite ions and the like to deposit needle-like plating on the surface of the conductor circuit. If the plating reaction does not proceed even after such an operation (no deposition)
On the contrary, there is also a problem that the reaction progresses too much and needle-like plating is deposited on a portion other than the conductor circuit (abnormal deposition), so that a reproducible result cannot be obtained.

SUMMARY OF THE INVENTION The present invention has been made to solve such problems of the prior art, and an object of the present invention is to perform a needle-like alloy plating process made of Cu-Ni-P on a substrate on which a conductive circuit is formed. When performing, prevent abnormal precipitation and non-precipitation, Cu-
It is an object of the present invention to provide a method for manufacturing a multilayer printed wiring board that can favorably form a needle-like alloy plating layer made of Ni-P.

[0008]

Means for Solving the Problems The inventor of the present invention has made intensive studies for realizing the above object, and as a result, has found that abnormal precipitation and non-precipitation are caused by the dissolved oxygen concentration in the plating solution. That is, the higher the concentration of dissolved oxygen in the plating solution, the more difficult the plating reaction to proceed. On the other hand, the lower the concentration of dissolved oxygen in the plating solution, the easier the plating reaction to proceed. Usually, since the plating solution of 65 to 75 ° C. is bubbled with air for the purpose of stirring the solution, the dissolved oxygen concentration in the plating solution is as high as 3 ppm or more, and the substrate on which the conductor circuit is formed is immersed in the plating solution. However, the plating reaction hardly proceeds. Further, as the plating reaction proceeds, the generated hydrogen reacts with the oxygen in the plating solution to decrease the oxygen concentration in the solution, thereby causing an abnormal precipitation phenomenon. Based on the above results, the gist configuration of the invention conceived by the inventor is as follows. (1) A method for manufacturing a multilayer printed wiring board in which an interlayer resin insulating layer and a new conductor circuit are sequentially laminated and formed on a substrate provided with a conductor circuit, and the conductor circuit is formed. The substrate is immersed in an aqueous solution containing a copper ion, a nickel ion, a complexing agent, a hypophosphite ion and a surfactant, and the dissolved oxygen concentration is adjusted to 1.5 to 2.5 ppm to form a substrate on the conductor circuit. A method for manufacturing a multilayer printed wiring board, comprising forming a roughened layer made of Cu-Ni-P.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION According to the present invention, after an inner conductor circuit or an outer conductor circuit is formed on a substrate, the substrate on which the conductor circuit is formed is treated with copper ions, nickel ions, a complexing agent, and hypophosphorous acid. It is characterized in that it is immersed in an aqueous solution containing ions and a surfactant and the dissolved oxygen concentration is adjusted to 1.5 to 2.5 ppm to form a roughened layer made of Cu-Ni-P on the conductor circuit. is there. According to the configuration of the present invention, the concentration of dissolved oxygen in the plating solution is set to 1.5 to 2.5 pp.
m, the initial dissolved oxygen concentration is low, and there is no non-precipitation on the conductor circuit. Further, since the dissolved oxygen concentration is kept within a certain range even if the plating reaction proceeds, abnormal deposition can be prevented. The dissolved oxygen concentration is reduced by bubbling of an inert gas, and is increased by bubbling of air. Therefore, the dissolved oxygen concentration is adjusted by bubbling an inert gas or air. The dissolved oxygen concentration is measured by Orbisphere.
Oxygen meter manufactured by Laboratories Japan
3600. As the inert gas, for example, nitrogen, argon, or the like can be used.

The roughened layer of the needle-shaped alloy made of Cu-Ni-P preferably has an overall thickness of 1 to 7 µm.
In the case of the above thickness, the interval between the interlayer resin insulating layers, and,
This is because the interval between the conductor circuits can be set smaller than that of the conventional multilayer printed wiring board, and the density and weight of the multilayer printed wiring board can be reduced.

The shape of the roughened layer of the alloy made of Cu-Ni-P is preferably acicular or porous. When the roughened layer is formed by plating, the shape of the roughened layer changes depending on the type of surfactant and the like, but it is necessary to select conditions that can form a needle-shaped or porous roughened layer. is there.

A coating layer made of a metal whose ionization tendency is larger than that of copper and not more than titanium or a noble metal is formed on the surface of the roughened layer of the alloy made of Cu-Ni-P. Is desirable. Further, the thickness of the roughened layer coating layer is preferably 0.1 to 2 μm. By forming the coating layer of these metals, direct contact between the electrolyte solution and the roughened layer can be prevented.

Examples of the metal having an ionization tendency larger than that of copper and not more than titanium include titanium, aluminum, zinc, iron, indium, thallium, cobalt, nickel, tin, lead, bismuth and the like. Among them, tin, nickel, cobalt, iron, lead and the like are advantageous because they can form a dense oxide film. Examples of the noble metal include gold, silver, platinum, and palladium. Therefore, at least one selected from the metals and the noble metals can be used for the roughened layer coating layer. Among these metals and noble metals, tin is particularly preferred. This is because tin can form a thin layer by electroless displacement plating and can be deposited and formed along the irregularities of the roughened layer. When tin is used as the metal, a tin borofluoride-thiourea solution or a tin chloride-thiourea solution is used. In this case, a Sn layer having a thickness of about 0.1 to 2 μm is formed by the substitution reaction of Cu—Sn. When a noble metal is used, a method such as sputtering or vapor deposition can be employed.

Next, a plating method for forming a roughened layer by depositing and growing a plating layer of an alloy of Cu-Ni-P on the surface of a conductor circuit in the present invention will be described. In the present invention, the substrate on which the inner conductor circuit or the outer conductor circuit is formed, a complexing agent, a copper compound, a nickel compound,
Cu-Ni-P is immersed in an aqueous plating solution consisting of hypophosphite and acetylene-containing polyoxyethylene-based surfactant to give vibration or oscillation to the substrate, or by supplying metal ions. A porous or needle-shaped alloy consisting of is deposited and grown to form a roughened layer of the alloy. The aqueous plating solution has a copper ion concentration, a nickel ion concentration, a hypophosphite ion concentration, and a complexing agent concentration,
0.007 to 0.160 mol / l, 0.00
1 to 0.023 mol / l, 0.1 to 1.0 mol /
1, it is desirable to adjust so as to be 0.01 to 0.2 mol / l. Further, the concentration of the surfactant is 0.1.
It is desirable to adjust so as to be 01 to 10 g / l.

As the complexing agent, for example, citric acid,
Tartaric acid, malic acid, EDTA, quadrol, glycine and the like. As the acetylene-containing polyoxyethylene-based surfactant, it is most preferable to use one having a structure represented by the following formulas (1) and (2). Such surfactants include, for example, 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-
Alkynediols such as dimethyl-4-octyne-3,6-diol and the like can be mentioned. These commercial products include:
For example, Surfynol 104 (porous), 440, 465, and 485 (all needle-shaped) manufactured by Nissin Chemical Co., Ltd. can be used.

[0016]

Embedded image

(In the above formula (1), m and n are 3
In the formula (2), R ¹ and R ² represent an alkyl group, and R ³ and R ⁴ represent a hydrogen atom or a lower alkyl group. ) The surface of the Cu-Ni-P alloy precipitated from such an electroless plating solution becomes acicular or porous. In the case of a porous alloy, the number of micropores is 100,000 to 1,000,000 per cm ^2.
00, generally between 3,000,000 and
It is included in the range of 300,000,000.
The diameter of the micropores is in the range of 0.01 to 100 μm, generally in the range of 0.1 to 10 μm.

In the present invention, it is desirable to use an adhesive for electroless plating as an interlayer resin insulating layer formed on the conductor circuit. The most suitable adhesive for electroless plating is one in which heat-resistant resin particles soluble in a cured acid or oxidizing agent are dispersed in an uncured heat-resistant resin hardly soluble in an acid or an oxidizing agent. is there. By treating with an acid or oxidizing agent solution, the heat-resistant resin particles are dissolved and removed, and a roughened surface composed of an octopus pot-shaped anchor can be formed on the surface of the adhesive layer.

In the above-mentioned adhesive for electroless plating, in particular, the cured heat-resistant resin particles include: 1) heat-resistant resin powder having an average particle diameter of 10 μm or less; 2) particles having a relatively large average particle diameter. And particles having a relatively small average particle diameter. This is because they can form more complex anchors. Examples of the heat-resistant resin that can be used include an epoxy resin, a polyimide resin, and a composite of an epoxy resin and a thermoplastic resin. Examples of the thermoplastic resin to be composited include polyether sulfone (PES). Examples of the heat-resistant resin particles soluble in a solution of an acid or an oxidizing agent include, for example, an epoxy resin (especially an epoxy resin cured with an amine-based curing agent), an amino resin, and the like. Further, as the solder resist used in the present invention, for example, a resist composed of an epoxy resin acrylate and an imidazole curing agent can be mentioned.

Next, one method of manufacturing the multilayer printed wiring board of the present invention will be described. (1) First, a wiring board having an inner copper pattern (inner conductor circuit) formed on a surface of a core board is manufactured. The formation of the inner conductor circuit on the core substrate is performed by etching the copper-clad laminate or by the following method. That is, a layer of an adhesive for electroless plating is formed on a substrate such as a glass epoxy substrate, a polyimide substrate, a ceramic substrate, or a metal substrate, and then, after the surface of the adhesive layer is roughened, a conductive layer is formed by electrolytic plating. Is formed, and this conductor layer is etched to form an inner conductor circuit.

A through hole is formed in the core substrate, and the front and rear wiring layers are electrically connected through the through hole. Further, resin may be filled between the through-holes and the inner conductor circuit of the core substrate to ensure smoothness. Particularly, in the present invention, a roughened layer of a porous or needle-like Cu-Ni-P alloy is formed on the inner conductor circuit surface of the core substrate and the land surface of the through hole by the above-described method. That is, after adjusting the dissolved oxygen concentration of the plating solution to 1.5 to 2.5 ppm, the substrate on which the inner conductor circuit is formed is immersed in the plating solution, and Cu-Ni-P is formed on the inner conductor circuit. A roughened layer of the alloy is formed. In addition, you may form the coating layer which consists of a metal whose ionization tendency is larger than copper and is titanium or less, or a noble metal on the surface of this roughened layer.

(2) Next, an interlayer resin insulating layer is formed on the wiring board manufactured in the above (1). In particular, in the present invention, it is desirable to use the above-mentioned adhesive for electroless plating as a material of the interlayer resin insulating layer. (3) After the formed adhesive layer for electroless plating is dried, openings for forming via holes are provided as necessary. In the case of a photosensitive resin, by exposing and developing and then thermosetting, and in the case of a thermosetting resin, by thermosetting and then laser processing, a via hole is formed in the interlayer resin insulating layer. An opening is provided.

(4) Next, resin particles soluble in an acid or an oxidizing agent present on the surface of the cured adhesive layer for electroless plating (interlayer resin insulating layer) are dissolved and removed with an acid or an oxidizing agent. The surface of the adhesive layer for electrolytic plating is roughened. Here, examples of the acid include mineral acids such as phosphoric acid, hydrochloric acid, and sulfuric acid; and organic acids such as formic acid and acetic acid. It is particularly preferable to use an organic acid. This is because when an organic acid is used, the metal conductor layer exposed from the via hole is hardly corroded during the roughening treatment. On the other hand, as the oxidizing agent, it is desirable to use an aqueous solution of chromic acid or permanganate (such as potassium permanganate).

(5) Next, a catalyst nucleus is applied to the wiring board whose surface has been roughened. It is desirable to use a noble metal ion or a noble metal colloid for providing the catalyst nucleus,
Generally, palladium chloride or palladium colloid is used. Note that it is desirable to perform a heat treatment to fix the catalyst core. Palladium is preferred as such a catalyst core.

(6) Next, electroless plating is performed on the surface of the interlayer resin insulating layer provided with the catalyst nucleus, and an electroless plating film is formed on the entire roughened surface. The thickness of the electroless plating film is 0.5 to
5 μm is preferred. Next, a plating resist is formed on the electroless plating film.

(7) Next, 5 to 5
Electroplating with a thickness of 20 μm is performed to form outer conductor circuits and via holes. After electroplating, nickel, tin, cobalt,
At least one or more metal layers selected from noble metals may be formed. This is because alloy plating made of Cu-Ni-P tends to precipitate on these metal layers. Further, since these metal layers act as a metal resist, there is an effect that excessive etching is prevented even in the subsequent etching step. Here, as the electroplating,
It is desirable to use copper plating. Furthermore, after the plating resist is removed, the electroless plating film existing under the plating resist is dissolved and removed with an etching solution comprising a mixed solution of sulfuric acid and hydrogen peroxide or an aqueous solution of sodium persulfate, ammonium persulfate, or the like. And an independent outer conductor circuit.

(8) Next, similarly to the case (1), after adjusting the dissolved oxygen concentration of the plating solution to 1.5 to 2.5 ppm, the substrate on which the outer conductor circuit is formed is immersed in the plating solution. Then, a roughened layer of a porous alloy of Cu-Ni-P is formed on the outer layer conductor circuit. On the surface of this roughened layer,
A coating layer made of a metal having a higher ionization tendency than copper and not more than titanium or a noble metal may be formed.

(9) Next, an adhesive layer for electroless plating is formed on the substrate as an interlayer resin insulating layer. (10) Further, the above steps (3) to (8) are repeated to provide an upper outer-layer conductor circuit, thereby obtaining a six-layer double-sided multilayer printed wiring board having three layers on one side.

The above description is an example in which a printed wiring board is manufactured by a method called a semi-additive method. After roughening an adhesive layer for electroless plating, a catalyst nucleus is provided, and a plating resist is formed. The method can be applied to a so-called full additive method in which a conductive circuit is formed by performing electroless plating.

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments. Example 1 A. Preparation of adhesive for electroless plating 1) 35 parts by weight of 25% acrylate of cresol novolac type epoxy resin (manufactured by Nippon Kayaku Co., Ltd., molecular weight: 2500), photosensitive monomer (Toa Gosei Co., Aronix M3)
25) 3.15 parts by weight, 0.5 parts by weight of defoamer and N-
A mixed composition was prepared by placing 3.6 parts by weight of methylpyrrolidone (NMP) in a container and mixing with stirring.

2) Polyether sulfone (PES) 12
Parts by weight, 7.2 parts by weight of an epoxy resin particle (manufactured by Sanyo Kasei Co., polymer pole) having an average particle size of 1.0 μm and 3.09 parts by weight of an epoxy resin particle having an average particle size of 0.5 μm were placed in another container and stirred. After mixing, 30 parts by weight of NMP was further added and stirred and mixed by a bead mill to prepare another mixed composition.

3) Imidazole curing agent (Shikoku Chemicals, 2
E4MZ-CN) 2 parts by weight, benzophenone 2 parts by weight as a photopolymerization initiator, Michler's ketone 0.
2 parts by weight and 1.5 parts by weight of NMP were placed in another container and mixed by stirring to prepare a mixed composition.
Then, an adhesive for electroless plating was obtained by mixing the mixed compositions prepared in 1), 2) and 3).

B. Manufacturing method of printed wiring board (1) 1 mm thick glass epoxy resin or BT (bismaleimide triazine) resin
A copper-clad laminate on which an 8 μm copper foil 8 was laminated was used as a starting material (see FIG. 1A). First, the copper-clad laminate is drilled, and then a plating resist is formed. Then, the substrate is subjected to an electroless copper plating process to form through holes 9, and the copper foil is patterned in a conventional manner. Then, an inner layer copper pattern (inner layer conductor circuit) 4 was formed on both surfaces of the substrate.

The substrate on which the inner conductor circuit 4 is formed is washed with water and dried, and then NaOH (10 g / l), NaClO
₂ (40 g / l) and an aqueous solution of Na ₃ PO ₄ (6 g / l) are subjected to an oxidation bath treatment as an oxidation bath (blackening bath), and the entire surface of the inner layer conductor circuit 4 including the through holes 9 is roughened. Face 4
a and 9a were formed (see FIG. 1B).

(2) A resin filler 10 containing an epoxy resin as a main component is applied to both surfaces of the substrate by using a printing machine to fill the space between the inner-layer conductor circuits 4 or the inside of the through holes 9 and heat and dry. went. That is, by this step, the resin filler 10 is placed between the inner layer conductor circuits 4 or through holes 9.
(See FIG. 1C).

(3) One surface of the substrate after the treatment of the above (2) is subjected to belt sanding using a belt polishing paper (manufactured by Sankyo Rikagaku Co., Ltd.) to form a surface of the inner conductor circuit 4 and a land surface of the through hole 9. Was polished so that the resin filler 10 did not remain, and then buffed to remove the scratches caused by the belt sander polishing. Such a series of polishing was similarly performed on the other surface of the substrate. Then, the filled resin filler 10 was cured by heating (see FIG. 1D).

In this manner, the surface layer portion of the resin filler 10 filled in the through holes 9 and the like and the roughened layer 4a on the upper surface of the inner conductor circuit 4 are removed to smooth both surfaces of the substrate, and the resin filler 10 and the inner layer are removed. A wiring board was obtained in which the side surfaces of the conductive circuit 4 were firmly adhered through the roughened surface 4a, and the inner wall surface of the through hole 9 was tightly adhered to the resin filler 10 through the roughened surface 9a.

(4) Further, a 2 μm-thick Cu—N
A roughened layer 11 of a porous alloy made of iP was formed, and a Sn layer having a thickness of 0.3 μm was provided on the surface of the roughened layer 11 (see FIG. 2A). However, the Sn layer is not shown.

The method of forming the roughened layer 11 is as follows. That is, the substrate was alkali-degreased and soft-etched, and then treated with a catalyst solution comprising palladium chloride and an organic acid to provide a Pd catalyst and activate the catalyst. Next, copper sulfate (3.2 × 10 ⁻² mol / l), nickel sulfate (2.4 × 10 ⁻³ mol / l), citric acid (5.2 × 10 ⁻² mol / l), Sodium phosphate (2.7 × 10 ⁻¹ mol / l), boric acid (5.0 × 1
0 ^-1 mol / l), a surfactant (manufactured by Nissin Chemical Industry Co., Ltd.)
Nitrogen gas was bubbled into an electroless copper plating bath having an aqueous solution of Surfynol 465) (1.0 g / l) at a pH of 9 and a liquid temperature of 70 ° C., and the dissolved oxygen concentration in the plating solution was also measured. Was reduced to 2.1 ppm. One minute after the bubbling was completed, the substrate in which the catalyst was activated was immersed in a plating solution subjected to bubbling treatment. Subsequently, 30 seconds after the immersion of the substrate, bubbling of air was started. The dissolved oxygen concentration was adjusted to 1.9 to 2.1 ppm. The dissolved oxygen concentration is measured by Orbisphere L
Oxygen meter 3 manufactured by laboratories Japan
600. By the plating treatment, a roughened layer 11 of a needle-shaped alloy made of Cu-Ni-P having a thickness of 5 µm was provided on the nickel layer on the surface of the land of the inner layer conductor circuit 4 and the through hole 9.

(5) An adhesive for electroless plating having the composition described in A above was applied twice on both sides of the substrate using a roll coater, and left in a horizontal state for 20 minutes.
For 30 minutes (see FIG. 2B).

(6) A photomask film on which a black circle having a diameter of 85 μm is printed is brought into close contact with both surfaces of the substrate on which the adhesive layer for electroless plating is formed in the above (5), and is 500 mJ / cm by an ultrahigh pressure mercury lamp. Exposure was at ^two intensities. This is spray-developed with a diethylene glycol dimethyl ether (DMDG) solution, so that the adhesive layer has a diameter of 85 mm.
An opening 6 for forming a via hole of μm was formed. further,
The substrate is exposed to ultra-high pressure mercury lamp at 3000 mJ / cm ² , and is subjected to a heat treatment at 100 ° C. for 1 hour and then at 150 ° C. for 5 hours, so that a hole having excellent dimensional accuracy equivalent to a photomask film (via). 18 μm thick interlayer resin insulation layer 2 (2a, 2a,
2b) was formed (see FIG. 2 (c)).

(7) The substrate having the opening 6 for forming a via hole was placed in an aqueous solution of chromic acid (700 g / l) at 73 ° C. for 2 hours.
The substrate was immersed for 0 minutes to dissolve and remove the epoxy resin particles present on the surface of the interlayer resin insulating layer 2 to roughen the surface to obtain a roughened surface. Then, it was immersed in a neutralizing solution (manufactured by Shipley) and washed with water (see FIG. 2D). Further, by applying a palladium catalyst (manufactured by Atotech) to the surface of the substrate subjected to the surface roughening treatment, catalyst nuclei were attached to the surface of the interlayer insulating material layer 2 and the inner wall surface of the via hole 6. .

(8) 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 0.8 μm on the entire rough surface (FIG. 3 (a)). )reference). [Electroless plating aqueous solution] EDTA 60 g / l Copper sulfate 10 g / l HCHO 6 ml / l NaOH 10 g / l α, α'-bipyridyl 80 mg / l Polyethylene glycol (PEG) 0.1 g / l [None Electroplating conditions] 20 minutes at a liquid temperature of 60 ° C

(9) A commercially available photosensitive dry film is affixed to the electroless copper plating film 12, a mask is placed thereon, and
Exposure at mJ / cm ² and development with a 0.8% aqueous sodium carbonate solution provided a plating resist 3 (see FIG. 3B).

(10) Next, electrolytic copper plating was performed under the following conditions to form a 13 μm-thick electrolytic copper plating film 13 (see FIG. 3C). [Electroplating aqueous solution] sulfuric acid 180 g / l copper sulfate 80 g / l [Electroplating conditions] Current density 1 A / dm ² hours 30 minutes Temperature Room temperature

(11) After the plating resist 3 is peeled and removed with a 5% KOH aqueous solution, 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. An outer conductor circuit 5 (including the via hole 7) having an L / S = 28/28 and a thickness of 11 μm including the electrolytic copper plating film 12 and the electrolytic copper plating film 13 was formed.

(12) The same processing as in (4) above is performed on the substrate on which the outer conductor circuit 5 is formed, and the surface of the outer conductor circuit 5 is roughened to a 2 μm thick Cu—Ni—P alloy. The layer 11 was formed (see FIG. 3D).

(13) By repeating the above steps (5) to (12), the outer conductor circuit 5 and the roughened layer 11
And finally a solder resist layer 14 having an opening
After forming the nickel plating film 15 and the gold plating film 16, solder bumps 17 were formed to obtain a multilayer printed wiring board having the solder bumps 17 (FIG. 4).
(A) to FIG. 5 (c)).

Comparative Example 1 In the step of providing a roughened layer of an alloy composed of Cu—Ni—P of (4) in the above-mentioned Example 1, plating was performed under the following conditions. In the same manner as in the above, a multilayer printed wiring board was obtained. That is, air was bubbled through the plating solution before the substrate was immersed in the plating solution. At this time, the dissolved oxygen concentration of the plating solution was 3.4 ppm. After stopping air bubbling, the substrate was immersed in a plating solution to perform plating. At this time, the dissolved oxygen concentration in the plating solution decreased from 3.4 ppm to 0.6 ppm with the plating time. The other conditions in the step (4) are the same as the conditions described in the step (4).

The 1 obtained in the above Example 1 and Comparative Example 1
The cross section of the 00 multilayer printed wiring boards was observed with an optical microscope, and the undeposited and abnormal deposits of the roughened layer made of the Cu-Ni-P alloy were inspected. As a result, in Example 1, non-precipitation and abnormal precipitation were not observed, but in Comparative Example 1, non-precipitation was observed in 37% of the multilayer printed wiring boards, and abnormal deposition was observed in 55% of the multilayer printed wiring boards. Was observed.

[0051]

As described above, according to the multilayer printed wiring board having the structure of the present invention, the conductor circuit has Cu-Ni-
When plating a needle-shaped alloy made of P, non-precipitation and abnormal precipitation of plating can be prevented.

[Brief description of the drawings]

FIGS. 1A to 1D are cross-sectional views showing a part of a manufacturing process of a multilayer printed wiring board according to the present invention.

FIGS. 2A to 2D are cross-sectional views showing a part of a manufacturing process of the multilayer printed wiring board of the present invention.

FIGS. 3A to 3D are cross-sectional views illustrating a part of the manufacturing process of the multilayer printed wiring board according to the present invention.

FIGS. 4A to 4D are cross-sectional views illustrating a part of the manufacturing process of the multilayer printed wiring board according to the present invention.

FIGS. 5A to 5C are cross-sectional views showing a part of the manufacturing process of the multilayer printed wiring board of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Interlayer resin insulation layer (adhesive layer for electroless plating) 3 Plating resist 4 Inner layer conductor circuit (Inner layer copper pattern) 4a Roughened surface 5 Outer layer conductor circuit 6 Via hole forming opening 7 Via hole 8 Copper foil 9 Through hole 9a Roughened surface 10 Resin filler 11 Roughened layer 12 Electroless plated film 13 Electroplated film 14 Solder resist layer 15 Nickel plated film 16 Gold plated film 17 Solder bump

Claims (1)

[Claims] 1. A method of manufacturing a multilayer printed wiring board in which an interlayer resin insulating layer and a new conductive circuit are sequentially formed on a substrate on which the conductive circuit is provided, thereby forming a multilayer structure. Copper substrate, nickel ion,
Immerse in an aqueous solution containing a complexing agent, hypophosphite ions and a surfactant, and adjust the dissolved oxygen concentration to 1.5 to 2.5 ppm.
And forming a roughened layer made of Cu-Ni-P on the conductive circuit.