JP2000124601A - Method for manufacturing printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent delay in signal propagation by providing a metal layer that is made of a specific element metal on the surface of a resin insulation layer and then cleaning the metal layer surface with acid, and forming a conductor circuit on the metal layer. SOLUTION: An interlayer resin insulation layer 12 is laminated on a resin substrate 1 with an inorganic fiber, and a metal layer 14 that is made of at least one type of metal which is selected from among the fourth to seventh periodic metal elements, Ni, Cr, Mo, Ti, W, Cu, Al, Sn, Pt, Pd, and Au that belong to the range of the fourth A group - the first B group of a long period type periodic table is provided on the surface of the interlayer resin insulation layer 12. After that, the surface of the metal layer 14 is cleaned with acid, and then a conductor circuit 19 that is made of an electroless plating film 15 is formed on the metal layer 14, thus improving the adhesion property between the metal layer 14 and the electroless plating film 15 and preventing the delay of signal propagation.

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 printed wiring board using a resin substrate, and more particularly to a method of manufacturing a printed circuit board having excellent adhesion between a metal layer provided on the surface of a resin insulating layer and a conductor circuit formed on the metal layer. In addition, the present invention relates to a method for manufacturing a printed wiring board capable of preventing a delay in signal propagation.

[0002]

2. Description of the Related Art As the frequency of a signal increases, the material of a package substrate is required to have a low dielectric constant and a low dielectric loss tangent. Therefore, the mainstream of the package substrate material is shifting from ceramic to resin.

Under such a background, as a technique relating to a printed wiring board using a resin substrate, for example, Japanese Patent Publication No.
No. 55555 discloses that an epoxy acrylate is formed as an interlayer resin insulating layer on a glass epoxy substrate on which a circuit is formed, a hole for forming a via hole is formed by using a photolithography technique, and the surface is roughened. A method has been proposed in which a resist is provided and a conductor circuit and a via hole are formed by electroless plating.

However, the surface of the interlayer resin insulating layer made of a resin such as epoxy acrylate and the surface of the conductor circuit must be roughened in order to ensure adhesion to the conductor circuit which is a metal. For this reason, when a high-frequency signal is propagated, the signal propagates only through the surface portion of the roughened conductor circuit due to the skin effect, and a delay in signal propagation occurs due to unevenness of the surface. was there. This problem was particularly remarkable when a resin substrate having a lower dielectric constant and a lower dielectric loss tangent than a ceramic substrate was used. Japanese Patent Application Laid-Open No. 7-45948 discloses a method in which a resin (eg, chromium, nickel, titanium) is formed by coating a resin on one surface of a ceramic or metal substrate by spin coating or the like and improving the adhesion to a conductor circuit on the resin layer. Are provided by sputtering, and a conductor circuit is formed thereon.

[0005]

However, when a conductor circuit is actually formed by using this technique, peeling is likely to occur between the metal layer made of a metal such as chromium, nickel, and titanium and the conductor circuit. It turned out that there was a problem. Such a problem occurs when a metal layer is provided on the surface of the resin insulating layer using a physical vapor deposition method,
Since the metal layer is exposed to a high temperature, its surface is oxidized. If a conductor circuit is formed as it is on the metal layer having an oxide layer formed on the surface, the oxidation occurs between the metal layer and the conductor circuit. This is because the interposition of the layer weakens the adhesion and facilitates the peeling of the conductor circuit. In addition, the inventors have found that even when a metal layer is provided by a chemical vapor deposition method or plating, surface oxidation occurs when the metal layer is left in the air, and the conductor circuit is easily peeled.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of such a resin substrate. The main object of the present invention is to prevent a delay in signal propagation and to prevent the surface of a resin insulating layer from being delayed. An object of the present invention is to provide a method for manufacturing a printed wiring board, which can manufacture a printed wiring board having excellent adhesion between a metal layer provided thereon and a conductive circuit.

[0007]

Means for Solving the Problems The inventors of the present invention have intensively studied for realizing the above-mentioned object, and as a result, have arrived at an invention having the following content as a gist configuration. That is, the method for manufacturing a printed wiring board of the present invention is a method for manufacturing a printed wiring board in which a resin insulating layer and a conductive circuit are formed on a resin substrate,
On the surface of the resin insulating layer, a fourth periodic table of a long period type
After providing a metal layer composed of at least one metal selected from Al and Sn in the fourth to seventh periods belonging to the range from Group A to Group 1B, the surface of the metal layer is washed with an acid. Then, a conductor circuit is formed on the metal layer.

[0008] In the above method of manufacturing a printed wiring board,
Fourth to seventh period metal elements, Al and Sn belonging to the range of Groups 4A to 1B of the periodic table of the long period type
At least one metal selected from Ni, C
It is preferably at least one or more metals selected from r, Mo, Ti, W, Cu, Al, Sn, Pt, Pd and Au. Further, it is preferable that the surface of the resin insulating layer is flat. Further, the acid is hydrochloric acid,
It is preferably at least one or more acids or mixed acids selected from sulfuric acid, acetic acid, and phosphoric acid.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for manufacturing a printed wiring board according to the present invention is a method for manufacturing a printed wiring board in which a resin insulating layer and a conductive circuit are formed on a resin substrate. A metal layer made of at least one metal selected from the group consisting of metal elements of the fourth to seventh periods belonging to the groups 4A to 1B of the long-periodic periodic table, Al and Sn. After that, the surface of the metal layer is washed with an acid, and then a conductor circuit is formed on the metal layer.

According to the above configuration of the present invention, after forming a metal layer on the surface of the resin insulating layer, the surface of the metal layer is washed with an acid to remove an oxide film. Therefore, the conductor circuit formed on the metal layer can be strongly adhered to the above-mentioned metal layer, and peeling of the conductor circuit can be prevented.
Further, since it is not necessary to form a roughened surface on the resin insulating layer, the surface is flat. Therefore, there is no roughened surface on the lower surface of the conductor circuit formed thereon and the surface is flat, so that there is no delay in signal propagation.

When forming a metal layer on the surface of the resin insulating layer, Ni, Cr, Mo, Ti, W, Cu, Al,
At least one selected from Sn, Pt, Pd and Au
It is desirable to use more than one kind of metal. Therefore, the metal layer may be a layer composed of a single metal among the above metals, or may be a layer of an alloy composed of two or more metals. In the present invention, examples of the method for forming the metal layer include physical vapor deposition (PVD), chemical vapor deposition (CVD), electroplating, and electroless plating. The physical vapor deposition method is not particularly limited, and examples thereof include sputtering, ion beam sputtering, and vacuum vapor deposition. As the chemical vapor deposition method (CVD), PE-CVD (Plasma) using MO (metal organic) such as allylcyclopentadiphenylpalladium, dimethylgold acetylacetonate, tin tetramethylacrylonitrile, or dicobalt octacarbonylacrylonitrile as a supply material is used. Enhance
d CVD) and the like.

The type of acid used for washing with the above-mentioned acid is not particularly limited, but at least one or more acids selected from hydrochloric acid, sulfuric acid, acetic acid and phosphoric acid or mixed acids are preferable. The washing temperature with an acid is desirably 25 to 60 ° C. because the washing ability is increased.

The thickness of the alloy layer is 0.1 to 2.0 μm
It is desirable that If the thickness is less than 0.1 μm, it becomes difficult to form a metal layer by electroplating, and the effect of adhesion is small. On the other hand, if it exceeds 2.0 μm, etching becomes difficult.

The resin insulating layer formed in the present invention is preferably made of a thermosetting resin, a thermoplastic resin, or a composite resin thereof. As thermosetting resin,
For example, thermosetting polyolefin resin, epoxy resin,
It is desirable to use at least one selected from a polyimide resin, a phenol resin, and a bismaleimide toazine resin. As the thermoplastic resin, for example, it is desirable to use engineering plastics such as polymethylpentene (PMP), polystyrene (PS), polyethersulfone (PES), polyphenylene ether (PPE), and polyphenylene sulfide (PPS). In the printed wiring board of the present invention, as the resin substrate, a substrate in which a conductor circuit is directly formed on a resin substrate is used, and a resin insulating layer and a conductor circuit may be respectively provided thereon. The above may be provided. Alternatively, a resin substrate on which a conductor circuit is not formed may be used, and a resin insulating layer and a conductor circuit may be respectively provided on the resin substrate, or two or more layers may be provided thereon. Further, the resin insulating layer and the conductor circuit may be provided on one surface of the resin substrate, or may be provided on both surfaces.

Hereinafter, a method of manufacturing a printed wiring board according to the present invention will be described by taking a multilayer printed wiring board as an example. (1) First, a wiring board having a lower conductive circuit on the surface of a resin substrate is manufactured. As the resin substrate, a resin substrate having inorganic fibers is desirable, and specific examples thereof include a glass cloth epoxy substrate, a glass cloth polyimide substrate, a glass cloth bismaleimide-triazine resin substrate, and a glass cloth fluorine resin substrate. The formation of the copper pattern (lower conductor circuit) of the resin substrate is performed by etching a copper-clad laminate in which copper foil is adhered to both surfaces of the resin substrate. Further, a through hole is formed in the resin substrate by a drill, and a through hole is formed by performing electroless plating on the wall surface of the through hole and the surface of the copper foil. Copper plating is preferred as the electroless plating.

Next, electrolytic plating is performed for thickening.
As the electrolytic plating, copper plating is preferable. After the electrolytic plating, the inner wall of the through hole and the surface of the electrolytic plating film may be roughened. Examples of the roughening treatment method include blackening (oxidation) -reduction treatment, spray treatment with a mixed aqueous solution of an organic acid and a cupric complex, treatment with Cu-Ni-P needle-like alloy plating, and the like. If necessary, a conductive paste may be filled in the through holes, and a conductive layer covering the conductive paste may be formed by electroless plating or electrolytic plating.

(2) A resin insulating layer is formed on both surfaces of the wiring board having the lower conductor circuit manufactured in the above (1). This resin insulating layer functions as an interlayer resin insulating layer of the printed wiring board. The resin insulating layer is formed by applying an uncured liquid or laminating a film-shaped resin by applying heat and pressure.

(3) Next, an opening for forming a via hole is formed in the formed resin insulating layer (hereinafter, referred to as an interlayer resin insulating layer) in order to secure electrical connection with the lower conductive circuit. The holes are formed by exposure and development using a photolithography technique or by laser light irradiation. At this time, examples of the laser light used include a carbon dioxide gas laser, an ultraviolet laser, and an excimer laser.

When a hole is formed by a carbon dioxide laser beam,
Perform desmear processing. The desmear treatment can be performed using an oxidizing agent composed of an aqueous solution such as chromic acid or permanganate, or may be treated by oxygen plasma, mixed plasma of CF ₄ and oxygen, corona discharge, or the like. The surface can also be modified by irradiating ultraviolet rays using a low-pressure mercury lamp. In particular, by performing a process using a mixed plasma of CF ₄ and oxygen, a hydrophilic group such as a hydroxyl group or a carbonyl group can be introduced into the resin surface. It is advantageous to perform the above treatment on the interlayer resin insulating layer because the adhesion with the metal layer to be formed later can be improved.

(4) On the surface of the interlayer resin insulating layer provided with the opening for forming a via hole in the above (3), the fourth period belonging to the range of Groups 4A to 1B of the long period type periodic table is provided. At least one selected from the metal elements in the seventh to seventh periods, Al and Sn
A metal layer made of at least one kind of metal is formed by a PVD method or the like.

(5) After the step (4), an acid treatment is performed,
The oxide film on the surface of the metal layer is removed. (6) Next, electroless plating is performed on the metal layer formed in the above (5). Copper plating is most suitable as electroless plating.
Further, the thickness of the electroless plating is preferably 0.1 to 5 μm. The thickness is set so that the film can be removed by etching without impairing the function as a conductive layer in electrolytic plating performed later. Note that this electroless plating is not essential and can be omitted.

(7) A plating resist is formed on the electroless plating film formed in (6). This plating resist
After laminating a photosensitive dry film, it is formed by performing exposure and development processing.

(8) Next, electrolytic plating is performed using the electroless plating film as a plating lead to thicken the conductor circuit. The thickness of the electrolytic plating film is preferably 5 to 30 μm.

(9) After forming the electrolytic plating film, the plating resist is peeled off, and the electroless plating film and the metal layer existing under the plating resist are removed by etching to form an independent conductor circuit. . As an etchant,
For example, sulfuric acid-hydrogen peroxide aqueous solution, ammonium persulfate, sodium persulfate, aqueous solution of persulfate such as potassium persulfate, ferric chloride, aqueous solution of cupric chloride, hydrochloric acid, nitric acid,
Hot dilute sulfuric acid and the like can be mentioned.

(10) Further, if necessary, metal elements of the fourth to seventh periods belonging to the range of Groups 4A to 1B of the long-period periodic table, Al and S
n, at least one kind of thin metal layer is formed by plating, PVD or CVD, and the above steps (2) to (9) are repeated. To form a multilayer printed wiring board.

In the above description, the semi-additive method is employed as a method of forming a conductor circuit, but a full-additive method may be employed. Hereinafter, description will be made based on embodiments.

[0027]

(Example 1) (1) A BT resin copper-clad laminate (Mitsubishi Corporation) in which 18 μm copper foil 2 is laminated on both sides of a 1.0 mm thick substrate 1 made of BT (bismaleimide triazine) resin. Gas Chemical Company, trade name: HL830-
1.0T12D) was used as a starting material (see FIG. 1A). First, this copper-clad laminate is drilled to form a through hole (see FIG. 1 (b)). Then, a palladium-tin colloid is adhered to the surface, and an electroless plating aqueous solution having the following composition is used. And electroless plating was performed to form a 0.7 μm electroless plating film on the entire surface of the substrate.

[Aqueous solution of electroless plating] EDTA 60 g / l Copper sulfate 10 g / l HCHO 8 ml / l NaOH 10 g / l α, α'-bipyridyl 80 mg / l Polyethylene glycol (PEG) 0.1 g / l l [Electroless plating conditions] 10 minutes at a liquid temperature of 70 ° C

Further, electrolytic copper plating was performed with an aqueous electrolytic copper plating solution having the following composition under the following conditions to form an electrolytic copper plating film having a thickness of 15 μm. [Electroplating aqueous solution] Sulfuric acid 170-200 g / l Copper sulfate 50-70 g / l Additive (manufactured by Atotex Japan Co., Ltd., trade name: Capparaside GL) 20-40 ml / l [Electroplating conditions] Current density 1. 5-2.3 A / dm ² temperature 23-26 ° C

(2) The conductor layer 3 is formed on the entire surface of the substrate by the above process.
(Including the through hole 3a) (FIG. 1)
After washing (see (c)) with water and drying, the substrate is
OH (20 g / l), NaClO ₂ (50 g / l), N
an oxidation bath (blackening bath) composed of an aqueous solution containing a ₃ PO ₄ (15.0 g / l), and NaOH (2.7 g / l);
It was subjected to an oxidation-reduction treatment using a reduction bath composed of an aqueous solution containing NaBH ₄ (1.0 g / l), and the through-hole 3a
A roughened surface 4 is provided on the entire surface of the conductor layer 3 including
(D)).

(3) Next, a metal particle paste containing copper particles having an average particle size of 15 μm (DD paste: manufactured by Tatsuta Electric Wire Co., Ltd.)
Non-conductive hole-filled copper paste) is filled into the through holes 3a by screen printing,
It was dried and cured at 80 ° C. for 2 hours. The roughened surface 4 and the through hole 3 formed on the surface of the conductor layer 3
The metal particle paste 5 protruding from a is removed by belt sander polishing using # 400 belt polishing paper (manufactured by Sankyo Rikagaku Co., Ltd.). Further, in order to remove scratches due to the belt sander polishing, alumina polishing or SiC granulation is performed. Then, the substrate surface was flattened (see FIG. 1E).

(4) The electroless copper plating film 6 having a thickness of 0.6 μm is formed by applying a palladium colloid catalyst in accordance with a conventional method on the surface of the substrate flattened in the above (3) and then performing electroless plating. It was formed (see FIG. 1 (f)).

(5) Next, electrolytic copper plating is performed under the following conditions to form an electrolytic copper plating film 7 having a thickness of 15 μm. In a step shown in FIG. Thickness was formed, and a portion to be the conductor layer 10 covering the metal particle paste 5 filled in the through holes 3a was formed.

[Electroplating aqueous solution] Sulfuric acid 170-200 g / l Copper sulfate 50-70 g / l Additive (manufactured by Atotech Japan Co., Ltd., trade name: Capparaside GL) 20-40 ml / l [Electroplating conditions] Current density 1.5 to 2.3 A / dm ² temperature 23 to 26 ° C

(6) A commercially available photosensitive dry film is adhered to both sides of the substrate on which the portions to be the lower conductor circuit 9 and the conductor layer 10 are formed, a mask is placed, and 100 mJ / c
After exposure with m ² , the resist film was developed with 0.8% sodium carbonate to form an etching resist 8 having a thickness of 15 μm (see FIG. 2A).

(7) Then, the plating film in the portion where the etching resist 8 is not formed is dissolved and removed by etching using a mixed solution of sulfuric acid and hydrogen peroxide. The lower conductive circuit 9 and the metal particle paste 5
Was formed (see FIG. 2B).

(8) Next, the surface of the conductor layer 10 covering the lower conductor circuit 9 and the metal particle paste 5 is coated with Cu-Ni-P
A roughened layer (uneven layer) 11 made of an alloy and having a thickness of 2.5 μm is formed, and a surface of the roughened layer 11 having a thickness of 0.3 μm
Was formed (see FIG. 2C). The method for forming these layers is as follows. FIG. 2C does not show the Sn layer.

That is, the substrate was acid-degreased and soft-etched, and then treated with a catalyst solution comprising palladium chloride and an organic acid to deposit a Pd catalyst. After activating this catalyst, copper sulfate (8 g) was used. / L), nickel sulfate (0.6
g / l), citric acid (15 g / l), sodium hypophosphite (29 g / l), boric acid (31 g / l), surfactant (Sufinol 465, manufactured by Nissin Chemical Industry Co., Ltd.) (0.
Electroless plating was performed in an electroless plating bath containing 1 g / l) and having a pH of 9 to form a roughened layer 11 (uneven layer) made of a Cu-Ni-P alloy on the entire surface of the conductor circuit. further,
Tin borofluoride (0.1 mol / l), thiourea (1.
(0 mol / l) was immersed in an electroless tin displacement plating bath having a pH of 1.2 and a temperature of 50 ° C. to provide a 0.3 μm thick Sn layer on the surface of the roughened layer.

(9) 35 parts by weight of a 25% acrylate of a cresol novolak type epoxy resin (manufactured by Nippon Kayaku Co., Ltd., molecular weight: 2500), 3.15 parts by weight of a photosensitive monomer (manufactured by Toagosei Co., Ltd., trade name: Aronix M325) 0.5 parts by weight of an antifoaming agent (manufactured by San Nopco, trade name: S-65)
Imidazole curing agent (manufactured by Shikoku Chemicals, trade name: 2E4M)
Z-CN) 2 parts by weight, photoinitiator benzophenone 2
A weight part, 0.2 parts by weight of Michler's ketone as a photosensitizer, and 1.5 parts by weight of N-methylpyrrolidone (NMP) were placed in a container, and stirred and mixed to prepare an acrylate composition of an epoxy resin. Next, this epoxy resin acrylate composition was applied to both surfaces of the substrate by a roll coater to form a resin layer 120 to be the interlayer resin insulating layer 12 (see FIG. 2D).

(10) After the formation of the resin layer 120,
Pre-baking was performed for one minute, and then exposure and development were performed with ultraviolet rays to form openings 13 for forming via holes. Further, thermal curing was performed at 150 ° C. for 4 hours to obtain an interlayer resin insulating layer 12 (see FIG. 2E). The thickness of the interlayer resin insulation layer 12 after thermosetting was 18 μm.

(11) Sputtering using Ni as a target is performed under the conditions of a pressure of 0.8 Pa, a temperature of 80 ° C., a power of 200 W, and a time of 20 minutes, and a Ni metal layer 14 having a thickness of 0.6 μm is formed on the interlayer resin insulating layer 12. (FIG. 3)
(See (a)). In addition, SV-4540 manufactured by Japan Vacuum Engineering Co., Ltd. was used as an apparatus for sputtering.

(12) A commercially available photosensitive dry film is attached to both sides of the substrate on which the metal layer 14 is formed in the above (11), a photomask film is placed, and after exposure at 100 mJ / cm ² , Development was performed with 0.8% sodium carbonate to form a pattern of a plating resist 16 having a thickness of 30 μm (see FIG. 3B).

(13) Further, using an acid containing sulfuric acid (150 g / l) at a temperature of 40 ° C. for 5 minutes, the Ni metal layer 1
4 was treated with an acid to remove the oxide layer on the surface. (14) Next, electrolytic plating was performed under the same conditions as described in (1) above to form an electrolytic plating film 15 having a thickness of 21 μm. This electrolytic plating film 15 means that the conductor circuit 9 is thickened and the via hole 17 is plated and filled (see FIG. 3C).

(15) Further, after the plating resist 16 is peeled off with 5% NaOH, the plating resist 1 is removed.
6 was removed by etching with an aqueous solution containing sodium persulfate (100 g / l) at 40 ° C. to form a 16 μm-thick Ni metal layer 14 and an electrolytic copper plating film 15. Upper layer conductor circuit 19 (via hole 1
7 (see FIG. 3D).

(16) Thereafter, the steps (9) to (15) were repeated to form a multilayer. In FIG. 4, FIG.
By repeating the steps (9) to (15) on the substrate having the upper conductor circuit 19 and the like formed in (d), the interlayer resin insulation layer 1 is formed.
2 and the upper conductor circuit 19 are formed in one layer, respectively (FIG. 4).
(See FIG. 4A), and a solder resist layer is formed thereon (see FIGS. 4B to 4C).

(17) That is, first, a cresol novolak type epoxy resin (manufactured by Nippon Kayaku Co., Ltd.) dissolved in diethylene glycol dimethyl ether (DMDG) so as to have a concentration of 60% by weight was sensitized by acrylizing 50% of epoxy groups. Oligomer for imparting property (molecular weight: 4000) 46.
67 parts by weight, 15.0 parts by weight of bisphenol A type epoxy resin (manufactured by Yuka Shell Co., trade name: Epicoat 1001) of 80 wt% dissolved in methyl ethyl ketone, imidazole hardener (manufactured by Shikoku Chemicals Co., trade name: 2E4MZ)
-CN) 1.6 parts by weight, 3 parts by weight of a polyacrylic monomer which is a photosensitive monomer (trade name: R604, manufactured by Nippon Kayaku Co., Ltd.), and similarly polyvalent acrylic monomer (trade name: DPE6A, manufactured by Kyoei Chemical Co., Ltd.) 0.5 part by weight, 0.71 part by weight of a dispersion antifoaming agent (manufactured by San Nopco Co., trade name: S-65) is placed in a container, stirred and mixed to prepare a mixed composition. A solder resist composition was prepared by adding 2 parts by weight of benzophenone (manufactured by Kanto Kagaku) as a photoinitiator and 0.2 parts by weight of Michler's ketone (manufactured by Kanto Kagaku) as a photosensitizer.

(18) Next, the above-mentioned solder resist composition is applied on both sides of the multilayer wiring board in a thickness of 20 μm, and after drying, a photolithography pattern is formed on a portion to be a solder resist opening. The mask is brought into close contact with the solder resist layer and exposed to ultraviolet light of 1000 mJ / cm ² ,
An opening was formed by developing with a DMTG solution. 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 μm solder resist pattern layer 18 was formed (see FIG. 4B).

(19) Next, the solder resist pattern layer 1
8 was immersed in a pH = 5 electroless nickel plating solution composed of nickel chloride (30 g / l), sodium hypophosphite (10 g / l), and sodium citrate (10 g / l) for 20 minutes. 5 μm in the lower part of the opening 21
m of nickel plating layer was formed.

Further, the substrate was electrolessly formed of potassium potassium cyanide (2 g / l), ammonium chloride (75 g / l), sodium citrate (50 g / l), and sodium hypophosphite (10 g / l). It was immersed in a plating solution at 93 ° C. for 23 seconds to form a film having a thickness of 0.1 mm on the nickel plating layer.
A gold plating layer 22 of 03 μm was formed. FIG.
In (c), the formed nickel plating layer and gold plating layer are combined and denoted by reference numeral 22.

(20) Then, a solder paste is printed on the opening 21 of the solder resist pattern layer 18 and
Bump (solder body) 2
3 was formed, and a multilayer wiring printed board having the solder bumps 23 was manufactured (see FIG. 4C).

(Example 2) Using a Cr target, sputtering was performed under the conditions of a gas pressure of 0.9 Pa · s and a sputtering time of 20 minutes to form a Cr metal layer having a thickness of 0.5 μm. A printed wiring board was manufactured in the same manner as in Example 1.

(Embodiment 3) P using a Pd target
A printed wiring board was manufactured in the same manner as in Example 1 except that a metal layer was formed.

(Example 4) T using a Ti target
A printed wiring board was manufactured in the same manner as in Example 1 except that the i metal layer was formed.

(Comparative Example 1) A printed wiring board was manufactured in the same manner as in Example 1 except that acid cleaning was not performed after the formation of the Ni metal layer. As described above, the peel strength of the printed wiring boards obtained in Examples 1 to 4 and Comparative Example 1 was measured. Further, the presence or absence of peeling between the metal layer and the electrolytic copper plating film was observed using an optical microscope. The results are shown in Table 1 below.

[0055]

[Table 1]

As is clear from the results shown in Table 1, after the metal layer was formed on the interlayer resin insulating layer, acid cleaning was performed to remove the oxide film on the surface of the metal layer. Adhesion with the film is improved, and peeling of the electrolytic copper plating film is prevented.

[0057]

As described above, according to the method of manufacturing a printed wiring board of the present invention, after a metal layer is formed on a resin insulating layer, acid cleaning is performed to remove an oxide film on the surface of the metal layer. Thereby, it is possible to prevent the electrolytic copper plating film from peeling off from the metal layer, and as a result, it is possible to improve the reliability of the conductor circuit. Further, by flattening the surface of the conductor circuit, a delay in signal propagation can be prevented.

[Brief description of the drawings]

FIGS. 1A to 1F are views showing a part of a manufacturing process of a printed wiring board of the present invention.

FIGS. 2A to 2E are views showing a part of a manufacturing process of the printed wiring board of the present invention.

FIGS. 3A to 3D are views showing a part of a manufacturing process of the printed wiring board of the present invention.

FIGS. 4A to 4C are views showing a part of a manufacturing process of the printed wiring board of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Copper foil 3 Conductive layer 3a Through hole 4 Roughened surface 5 Metal particle paste 6 Electroless copper plating film 7, 15 Electrolytic copper plating film 8 Etching resist 9 Lower conductor circuit 10 Conductor layer 11 Roughened layer 120 Resin layer 12 Interlayer resin insulation layer 13, 21 Opening 14 Metal layer 16 Plating resist 17 Via hole 18 Solder resist layer 19 Upper conductor circuit 22 Nickel plating layer and gold plating layer 23 Solder bump

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4E351 AA02 AA03 AA04 BB01 BB31 BB32 BB33 BB35 CC06 CC07 CC11 DD04 DD06 DD17 DD19 DD20 5E343 AA02 AA07 AA15 AA16 AA17 AA18 BB23 BB24 BB28 BB34 BB40 BB38 BB38 BB38 BB38 BB38 CC34 CC36 CC38 CC50 CC73 CC78 DD03 DD24 DD25 DD26 DD33 DD43 EE32 ER16 ER18

Claims (4)

[Claims] 1. A method for manufacturing a printed wiring board, wherein a resin insulating layer and a conductive circuit are formed on a resin substrate, wherein a group 4A group of a long-period periodic table is formed on a surface of the resin insulating layer. ~
After providing a metal layer made of at least one metal selected from Al and Sn in the fourth to seventh periods belonging to the range of Group 1B, the surface of the metal layer is washed with an acid, Forming a conductive circuit on the metal layer. 2. A metal element of a fourth period to a seventh period belonging to the range of Groups 4A to 1B of the periodic table of the long period type,
At least one metal selected from Al and Sn is Ni, Cr, Mo, Ti, W, Cu, Al, Sn,
The method for manufacturing a printed wiring board according to claim 1, wherein the method is at least one metal selected from Pt, Pd, and Au. 3. The method according to claim 1, wherein the surface of the resin insulating layer is flat. 4. The method according to claim 1, wherein the acid is at least one or more acids selected from hydrochloric acid, sulfuric acid, acetic acid, and phosphoric acid or a mixed acid.