JP3056896B2 - Method for manufacturing multilayer wiring board - Google Patents

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 wiring board provided with copper circuits and through holes.

[0002]

2. Description of the Related Art In a multilayer wiring board, a layer of copper 2 made of copper foil or the like is provided on the surface of an insulating substrate 1 to form an inner layer material 3 as shown in FIG. The surface of copper 2 is oxidized to form a layer of copper oxide 4 made of cupric oxide.
As shown in (b), the surface of the copper 2 is roughened and then the copper 2 layer is etched to form a circuit, and then the outer layer material 5 made of copper foil or the like is stacked via a prepreg and heated. As shown in FIG. 9C, the outer layer material 5 is formed on the inner layer material 3 by the prepreg insulating adhesive layer 6 by pressure molding or pressure molding.
Are laminated and bonded to form a multilayer laminate 10, and through holes 7 are formed in the multilayer laminate 10 as shown in FIG. 9 (d), and further the through holes 7 are formed as shown in FIG. 9 (e). It is manufactured by applying a copper plating 8 to the inner periphery of the through hole 7 to make the inside of the through hole 7 electrically conductive.

In this multilayer wiring board, it is necessary to ensure adhesion between the circuit of copper 2 formed on the inner layer material 3 and the insulating adhesive layer 6 by a prepreg for laminating the outer layer material 5. Further, as described above, the copper oxide 4 is provided on the surface of the copper 2 to roughen the surface, thereby improving the adhesion between the copper 2 and the insulating adhesive layer 6. However, like this, copper 2
Is oxidized to form copper oxide 4 on the surface of copper 2,
When copper plating 8 is performed on the inner periphery of the through hole 7 after the through hole 7 is drilled, the copper oxide 4 exposed on the inner periphery of the through hole 7 is dissolved in the acid of the plating solution and eroded by the acid. The so-called haloing 11 occurs as shown in FIG.
In a multi-layered wiring board having a high density, reliability such as conduction reliability, insulation reliability, heat resistance reliability, and adhesion reliability may be reduced. This is because metallic copper has a lower chemical affinity for the acid in the plating solution than hydrogen and does not directly produce hydroxides or metal salts, but in the state of copper oxide (monovalent or divalent), hydrochloric acid or This is because the metal salt easily reacts with an acid such as sulfuric acid to form and dissolve the metal salt.

[0004]

Therefore, various studies have hitherto been made to prevent such a haloing phenomenon. For example, in JP-A-61-140194, after oxidizing a copper surface, the copper oxide is reduced in an alkaline solution such as sodium hydroxide solution so that the copper oxide is not dissolved in an acid. We try to increase acid resistance. In Japanese Patent Application Laid-Open No. 2-550555, after the surface of copper is coated with copper oxide, it is exposed to a chromic acid aqueous solution so as to generate large resistance to delamination between layers and reduce haloing. ing. Further, in Japanese Unexamined Patent Publication No. 2-58898, a copper oxide film layer is immersed in 1/30 to 1/10 normal sulfuric acid,
By dissolving a part of the oxide film layer, the occurrence of the haloing phenomenon is prevented.

[0005] However, these are all due to chemical treatment using a chemical solution, and contaminants due to residues are generated on the surface of the inner layer material in a drying step after the treatment, resulting in poor appearance and the copper 2 and the insulating adhesive layer. There is a risk of causing poor adhesion between the substrate and the substrate, and the cost of light and heat in the drying process and the cost of treating the waste liquid after the use of the chemical solution are required. Furthermore, the amount of the chemical which acts on the copper oxide 4 is small compared to the total amount of the chemical, and most of the chemical is wasteful of resources and energy. There is also the problem of deteriorating the environment.

In Japanese Patent Application Laid-Open No. 4-85024,
The oxidized copper is treated in a reducing gas atmosphere. Specifically, the oxidized copper foil is put into a dryer capable of vacuum suction and dried at normal pressure at 150 ° C. for 10 minutes. Then, the inside of the dryer was suctioned under reduced pressure while increasing the temperature, nitrogen gas was introduced, and vacuum suction was performed again.
It is necessary to perform the reduction treatment at 20 ° C. for 10 minutes, and as a result of performing the treatment at such a high temperature, stress is generated due to the difference in the coefficient of thermal expansion between copper and the resin, and the adhesiveness between the copper and the resin is reduced. Exposure to copper may cause the delamination, and exposure to copper in an atmosphere of high-concentration hydrogen may promote hydrogen embrittlement of copper, thereby increasing conduction resistance and, in the worst case, causing disconnection.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned points, and has been developed by prepreg insulation bonding by roughening a copper surface.
A method for manufacturing a multilayer wiring board, which can enhance the adhesiveness with a layer, and can solve the problem of performing a chemical treatment using a chemical solution or a treatment in a high-temperature gas atmosphere while improving the haloing resistance. The purpose is to provide.

[0008]

SUMMARY OF THE INVENTION According to the present invention, a copper surface of an inner layer material composed of an insulating substrate and surface copper is oxidized,
After laminating and bonding the outer layer material to this inner layer material via a prepreg, and laminating and bonding, the through-hole is drilled and copper plating is performed in the through-hole to manufacture a multilayer wiring board. The copper oxide on the treated copper surface is treated and reduced in an ionizing atmosphere .
Thus , lamination bonding is performed after the copper surface is roughened .

In the present invention, when performing the above-mentioned reduction treatment in an ionized atmosphere by using a plasma containing hydrogen, the copper oxide surface can be reduced by applying a negative bias voltage lower than the plasma potential. Further, in the present invention, when performing the reduction treatment under the ionizing atmosphere by using a plasma containing hydrogen, the reduction can be performed while forming a magnetic field near the surface of the copper oxide.

Further, in the present invention, the reduction treatment in an ionizing atmosphere may be performed while controlling changes in the generated gas, color tone, and emission spectrum accompanying the reduction reaction of the copper oxide. Further, in the present invention, a post-treatment of forming a protective film on the surface of copper reduced by the treatment in an ionizing atmosphere may be performed.

In addition, in the present invention, an outer layer material may be laminated via a prepreg on an inner layer material reduced in an ionizing atmosphere, and then laminated and bonded while maintaining a vacuum state. Further, in the present invention, the outer layer material may be laminated via a prepreg on the inner layer material reduced in an ionizing atmosphere, and then laminated and bonded in the ionizing atmosphere. Hereinafter, the present invention will be described in detail.

The insulating substrate 1 may be formed of a laminate such as an epoxy resin-impregnated glass cloth substrate laminate or a polyimide resin-impregnated glass cloth substrate laminate. An inner layer material 3 as shown in FIG. 1A can be prepared by laminating copper 2 such as foil. First, the surface of the copper 2 is oxidized. The oxidation treatment can be performed using an oxidizing agent solution such as a potassium persulfate solution. By oxidizing in this manner, copper oxide 4 can be formed on the surface of copper 2 as shown in FIG. 1B, and copper oxide 4 is mainly formed by cupric oxide (CuO). Is done. By this oxidation treatment, fine projections are formed on the surface of the copper 2 and the copper 2
The surface can be roughened by providing irregularities.

After the copper oxide 4 is formed on the surface of the copper 2 of the inner layer material 3 in this way, the copper oxide 4 is reduced to metallic copper while keeping the surface irregularities. In the present invention, this reduction treatment is performed by performing the treatment in an ionizing atmosphere. Here, under the ionizing atmosphere in the present invention,
This refers to a state in which charged particles such as plasma or ion beams or a mixture of charged particles and electrons exists. This plasma, as recognized by academics, does not belong to any of the three states of solid-liquid-gas substances, and is composed of charged particles and electrically neutral particles. This is the fourth phase state. In addition, an ion beam refers to a beam extracted and accelerated from ions in plasma. The reduction treatment in the ionized atmosphere may be performed before or after forming the circuit pattern from the copper 2 of the inner layer material 3, or may be performed in a state of a copper foil laminated on the inner layer material 3.

After the copper oxide 4 on the surface of the copper 2 of the inner layer material 3 is reduced to metallic copper 9 as shown in FIG. 1C as described above, the outer layer made of copper foil or the like is interposed via a prepreg. As shown in FIG. 1 (d), the insulating adhesive layer 6 made of prepreg
The outer layer material 5 is laminated and adhered to the inner layer material 3 to form a multilayer laminate 10, and through holes 7 are formed in the multilayer laminate 10 as shown in FIG.
By applying copper plating 8 on the inner periphery of the through hole 7 and electrically connecting the inside of the through hole 7 as shown in (f), a multilayer wiring board can be manufactured.

[0015]

[Function] Oxidation and reduction treatment of copper surface of inner layer material, rough surface
After that, the lamination bonding is performed.
Copper circuit and outer layer material are laminated on the rough surface formed on the copper surface.
Prepreg to improve the adhesion to the insulating adhesive layer.
Can be. By treating and reducing the copper oxide on the surface of the oxidized copper of the inner layer material in an ionizing atmosphere, the copper oxide is not dissolved in an acid, and the acid resistance can be improved. It is possible to prevent the occurrence of the haloing phenomenon in processing and copper plating. In addition, since the reduction treatment is performed in an ionizing atmosphere such as a plasma or ion beam, there is no problem in performing a chemical treatment using a chemical solution or a treatment in a high-temperature gas atmosphere.

[0016]

Next, the present invention will be described in more detail with reference to examples. (Example 1) An inner layer material 3 formed by laminating a 35-μm-thick copper foil on both sides of an insulating substrate (epoxy resin-impregnated glass cloth substrate laminate) having a thickness of 1 mm was oxidized with a potassium persulfate solution. A copper oxide was formed on the surface of copper (FIG. 1).
(B)). The inner layer material 3 is put into the sample processing chamber 13 as shown in FIG. 2 and set in the sample holder 19 between the upper and lower electrodes 14 and 15 (the casing of the sample processing chamber 13 also serves as the electrode 15). 0.001 Torr
The pressure was reduced to r or less. Thereafter, hydrogen gas is introduced into the sample processing chamber 13 from the gas inlet 16, and a high frequency input of 500 W and a frequency of 13.56 MH is performed under a constant pressure of 0.1 Torr.
Glow discharge was performed under the condition of z, and the treatment was performed for several seconds to several minutes in the generated hydrogen plasma. In FIG. 2, reference numeral 17 denotes a high frequency power source for discharging.

At this time, in order to increase the kinetic energy of the ions incident on the copper oxide on the copper surface of the inner layer material 3 and to promote the reduction reaction efficiently, a bias voltage of -100 V is applied to the inner layer material 3 to the variable DC voltage for bias. The voltage was applied from the power supply 18. Further, during the above-mentioned plasma treatment, the operation was performed while monitoring the gas generated by the reduction reaction using a quadrupole mass filter type partial pressure gauge 35 as shown in FIG. That is, before the prepreg treatment, the peak of the water molecule (m / e = 1) as shown in FIG.
8) hardly occurs, the peak of water molecules increases during plasma processing as shown in FIG. 4 (b), and almost no water molecule peak occurs as shown in FIG. 4 (c) when the plasma processing ends. . Therefore, by monitoring the generated gas and controlling the point at which the peak of water molecules hardly occurs as the end point of the plasma treatment, the copper oxide reduction treatment by the plasma treatment can be performed with high work efficiency. . In addition, in addition to detecting the change in the generated gas as described above, a change in the color tone of the copper surface, that is, a change in the color tone in which copper oxide is reduced from black to metallic copper and changes to copper color, or plasma Detecting changes in the emission spectrum,
Other can and TURMERIC such Oko a controlled by detection.

After the reduction treatment as described above, three prepregs (epoxy resin-impregnated glass cloth base material) having a thickness of 0.1 mm are provided above and below the inner layer material 3 and have a thickness of 20 μm.
Were laminated and subjected to heat and pressure lamination to form a multilayer laminate 10 having a four-layer configuration (FIG. 1 (d)). Then, this multilayer laminated plate 10 is drilled to have a diameter of 0.4 mm.
(FIG. 1 (e)).

After immersing the multilayer laminate in which the through-holes 7 are perforated in a 17.5% hydrochloric acid aqueous solution, the insulating adhesive layer 6 is peeled off, and the area around the through-holes 7 is observed with a microscope to determine the size of the haloing. Was measured, sample 10
The size of the harrowing was 0 μm in all of the 0 pieces. For comparison, the size of the halo was also measured for a multilayer wiring board that had not been subjected to the reduction treatment as described above. As a result, the halo occurred in a size of 400 to 600 μm in 100 samples. After processing the through hole 7 as described above, copper plating 8 is applied to the inner periphery of the through hole 7 to finish the multilayer wiring board (FIG. 1F). When the height was measured, the size of the halo was 0 μm.

The adhesive strength between the copper 2 and the insulating adhesive layer 6 is 9
When measured at 0 ° peel strength, it exceeded 1.5 kgf / cm in all 100 measured samples. Furthermore, when the multilayer laminate was immersed in a solder bath at 300 ° C. for 1 minute in order to examine the solder heat resistance, all of the 100 samples did not have defects such as blisters and peeling.

As described in the first embodiment, by using hydrogen in the form of plasma, the method described in Japanese Patent Laid-Open No. 4-85024 is used.
Patent Literature 1 discloses a large amount of ions and radicals that contribute to the reaction rather than heating under a hydrogen atmosphere, so that copper oxide can be efficiently reduced and a low-temperature treatment can be performed. It is possible to obtain a high effect of preventing delamination of the wiring board and to improve dimensional stability.

Example 2 An inner layer material 3 having a copper oxide formed on the surface of copper by oxidation treatment in the same manner as in Example 1 is placed in a sample processing chamber 13 as shown in FIG. , 15 and the pressure in the sample processing chamber 13 was reduced to 0.001 Torr or less. The hydrogen gas atmosphere from the gas inlet 16 into the sample processing chamber 13 after this by introducing hydrogen gas, the high frequency input 500W under a constant pressure of 0.1 Torr, was glow discharge conditions of frequency 13.56 MHz, generated Treated for several seconds to several minutes in hydrogen plasma.

At this time, in order to increase the spatial density of hydrogen ions and hydrogen radicals in the vicinity of the inner layer material 3 and to promote the reduction reaction efficiently, a high-density plasma generating magnet 20 is provided to generate a magnetic field parallel to the inner layer material 3. It was formed. In FIG. 5, reference numeral 37 denotes a line of magnetic force. Also, in the same manner as in Example 1,
The gas generated by the reduction reaction was monitored using a quadrupole mass filter type partial pressure gauge 35 with a monitor device 36 , and the point at which the peak of water molecules (m / e = 18) almost disappeared was regarded as the end point of the plasma treatment.

Then, when a multilayer wiring board was prepared in the same manner as in Example 1, no haloing occurred even in Example 2, and the interlayer adhesion and solder heat resistance were equivalent to those of Example 1. Met. (Embodiment 3) An inner layer material 3 having a copper oxide formed on the surface of copper by oxidizing treatment in the same manner as in Embodiment 1 is placed in a sample processing chamber 13 and set between upper and lower electrodes 14 and 15 to perform sample processing. Room 13
The pressure was reduced to 0.001 Torr or less. Thereafter, hydrogen gas is introduced into the sample processing chamber 13 from the gas inlet 16 to form a hydrogen gas atmosphere, and glow discharge is performed under a constant pressure of 0.1 Torr under the conditions of a high-frequency input of 500 W and a frequency of 13.56 MHz to generate hydrogen. Treated for several seconds to several minutes in the plasma.

As a post-process after the reduction process is performed in this manner (FIG. 6A shows the surface of the copper 2 after the reduction process), as shown in FIG. 22
The discharge gas and the reaction gas are respectively introduced from FIG. 6 and the chromium oxide layer is formed by plasma CVD (chemical vapor deposition).
(C) As shown in FIG.
As vapor phase growth.

After the reduction treatment is performed as described above, the thickness of the inner layer material 3 is reduced to 0.
A multilayer laminate having a four-layer configuration was prepared by laminating and forming three 1 mm prepregs and a copper foil having a thickness of 20 μm. The multilayer laminate is drilled to form a through hole 7 having a diameter of 0.4 mm, immersed in a 17.5% hydrochloric acid aqueous solution, peeling off the insulating adhesive layer, and measuring the size of haloing with a microscope. Then, sample 2
The halo size was 0 μm in all 00 pieces. Further, when the adhesive strength between the copper and the insulating adhesive layer was measured at a peel strength of 90 °, it exceeded 1.7 kgf / cm in all of the 50 measured samples. Further, in order to examine the solder heat resistance, the sample was immersed in a solder bath at 300 ° C. for 1 minute, and all of the 100 samples did not have any problems such as blisters and peeling. Also, when the through hole was formed and the inner wall was subjected to copper plating to finish the multilayer wiring board, the size of the halo was measured in the same manner, and the size of the halo was 0 μm.

In this embodiment, after the reduction treatment, chromium oxide is subjected to plasma CVD to form a protective film 23 for preventing oxidation on the surface of the copper 2 and the surface of the reduced copper 2 is oxidized again. However, the means for forming the protective film 23 is not limited to plasma CVD, and the material formed as a post-process is not limited to an antioxidant.

(Example 4) An inner layer material 3 having a copper oxide formed on the surface of copper by oxidation treatment in the same manner as in Example 1 is put into a sample processing chamber 13 and set between upper and lower electrodes 14 and 15. The pressure in the sample processing chamber 13 was reduced to 0.001 Torr or less.
Thereafter, hydrogen gas is introduced into the sample processing chamber 13 from the gas inlet 16 to form a hydrogen gas atmosphere, and a high-frequency input of 500 W and a frequency of 13.56 MH under a constant pressure of 0.1 Torr.
Glow discharge was performed under the condition of z, and the treatment was performed for several seconds to several minutes in the generated hydrogen plasma. Thereafter, the pressure was reduced, and the inside of the sample processing chamber 13 was again reduced to 0.001 Torr or less.

As shown in FIG. 7, the sample processing chamber 13 is connected to a vacuum lamination molding chamber 25 via a gate valve 24, and a belt conveyor or the like is provided between the sample processing chamber 13 and the vacuum lamination molding chamber 25. A transport device 30 is provided. The inside of the vacuum lamination molding chamber 25 is the same as the inside of the sample processing chamber 13 at 0.001 Torr.
The pressure is reduced to r or less, and the inner layer material 3 that has been subjected to the decompression treatment is sent by the transfer device 30 into the vacuum lamination molding chamber 25.
Three prepregs 26 and a copper foil 27 having a thickness of 20 μm are layered on the upper and lower sides of the inner layer material 3 as an outer layer material, and a pair of the prepregs 26 is sandwiched between forming plates 28 made of an aluminum plate. It was set between press plates 29, and heated and pressed to form a laminate, thereby producing a multilayer laminate having a four-layer structure.

The adhesive strength between the copper 2 and the insulating adhesive layer 6 of this multilayer laminate was measured at 90 ° peel strength.
2 kgf / in all 100 samples measured
cm, and an even higher adhesive strength than that of Example 1 was obtained. In addition, evaluations on haloing and heat resistance were equivalent to those in Example 1. (Embodiment 5) When the inner layer material 3 is subjected to reduction treatment and lamination molding in the same manner as in Embodiment 4 described above, as shown in FIG. Plasma was generated, and the laminate was formed while being heated by the radiant heat. Heating by radiant heat in an ionizing atmosphere in which plasma is generated as described above to perform lamination molding enables uniform heating and uniform bonding between the inner layer material 3, the prepreg 26 and the copper foil 27. Can be done. By the way,
The deviation parallel sum of the adhesive force of the conventional heat transfer system is 0.44 kgf
/ Cm, whereas in the radiant heat method using plasma, it was 0.02 kgf / cm.

[0031]

As described above, according to the present invention, the copper surface of the inner layer material composed of the insulating substrate and the surface copper is oxidized, and the outer layer material is laminated and bonded to the inner layer material via the prepreg. After that, in producing a multilayer wiring board by performing copper plating in the through hole while performing drilling of the through hole, the copper oxide on the surface of the oxidized copper of the inner layer material is treated in an ionizing atmosphere. be reduced
By doing so, after laminating the copper surface , lamination bonding was performed, so that the rough surface formed on the copper surface and the copper circuit
Contact with insulating adhesive layer by prepreg laminated with outer layer material
As well as being able to enhance the adhesion, the copper oxide can be reduced to a state in which it is not dissolved in an acid to improve the acid resistance,
It can prevent the occurrence of haloing phenomenon when processing through-holes and copper plating, and since this reduction treatment is performed in an ionizing atmosphere, chemical treatment using chemicals or high-temperature gas atmosphere This eliminates the problem of performing the processing.

Further, when the reduction treatment in the ionizing atmosphere is performed by using a plasma containing hydrogen, the copper oxide surface is reduced by applying a negative bias voltage lower than the plasma potential. And the reduction reaction can proceed efficiently. Furthermore, when the reduction treatment under the ionizing atmosphere is performed using a plasma containing hydrogen, the reduction is performed while forming a magnetic field near the surface of the copper oxide. Can be advanced.

In addition, the reduction treatment in an ionizing atmosphere is
Control is performed while detecting changes in the generated gas, color tone, and emission spectrum associated with the reduction reaction of copper oxide, so that by detecting these changes, the end point of the plasma processing can be detected and the plasma processing can be controlled. In addition, it is possible to perform a copper oxide reduction treatment by a plasma treatment with high work efficiency.

Further, since the post-treatment of forming a protective film on the surface of the reduced copper by the treatment in an ionizing atmosphere is performed, the oxidation of the surface of the reduced copper is prevented by the protective film. And the occurrence of the haloing phenomenon can be reliably prevented. In addition, after the outer layer material is laminated via the prepreg on the inner layer material that has been subjected to the reduction treatment in an ionizing atmosphere, the vacuum state is maintained and the lamination bonding is performed, so that the interlayer adhesion by lamination molding can be enhanced. It is.

Further, after the outer layer material is layered through the prepreg on the inner layer material reduced in an ionizing atmosphere, and then laminated and bonded in the ionizing atmosphere, the material is uniformly heated by radiant heat in the ionizing atmosphere. Thus, lamination molding can be performed, and the adhesive strength between the layers can be made uniform.

[Brief description of the drawings]

FIG. 1 shows each step of a manufacturing method according to the present invention, and (a) to (f) are cross-sectional views, respectively.

FIG. 2 is a schematic sectional view showing a plasma process.

FIG. 3 is a schematic diagram showing a device for monitoring generated gas.

FIG. 4 shows the spectral intensity of a water molecule;
(A) to (c) are graphs of the peaks, respectively.

FIG. 5 is a schematic sectional view showing plasma processing using a high-density plasma generating magnet.

FIG. 6 shows a process of plasma CVD.
(A) to (d) are schematic cross-sectional views.

FIG. 7 is a schematic sectional view showing vacuum lamination molding.

FIG. 8 is a schematic view showing lamination molding using heating by plasma.

FIGS. 9A to 9E show respective steps of a manufacturing method in a conventional example, and FIGS. 9A to 9E are cross-sectional views.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 insulating substrate 2 copper 3 inner layer material 4 copper oxide 5 outer layer material 6 insulating adhesive layer 7 through hole 8 copper plating 9 reduced copper 23 protective film

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2-306696 (JP, A) JP-A-63-147393 (JP, A) JP-A-3-1722752 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) H05K 3/38 H05K 3/46

Claims (7)

(57) [Claims] An oxidation treatment is performed on a copper surface of an inner layer material composed of an insulating substrate and copper on the surface, and an outer layer material is laminated and adhered to the inner layer material via a prepreg. When manufacturing a multilayer wiring board by performing copper plating in the through hole while performing
By treating and reducing the copper oxide on the oxidized copper surface of the inner layer material in an ionizing atmosphere , the copper surface is roughened.
A method for producing a multilayer wiring board, comprising laminating and bonding after planarization . 2. The method according to claim 1, wherein the reduction treatment in an ionizing atmosphere is a plasma containing hydrogen, and the copper oxide surface is reduced by applying a negative bias voltage lower than the plasma potential. 3. The method for producing a multilayer wiring board according to item 1. 3. The multilayer wiring board according to claim 1, wherein the reduction treatment in the ionizing atmosphere is a plasma containing hydrogen, and the reduction is performed while forming a magnetic field near the surface of the copper oxide. Manufacturing method. 4. The method according to claim 1, wherein the reduction treatment in an ionizing atmosphere is performed while controlling a change in a generated gas, a color tone, and an emission spectrum accompanying the reduction reaction of the copper oxide. 3. The method for manufacturing a multilayer wiring board according to any one of 3. 5. The method for producing a multilayer wiring board according to claim 1, wherein a post-treatment for forming a protective film on the surface of the copper reduced by the treatment in an ionizing atmosphere is performed. . 6. The method according to claim 1, wherein an outer layer material is laminated via a prepreg on the inner layer material reduced in an ionizing atmosphere, and then laminated and bonded while maintaining a vacuum state.
6. The method for manufacturing a multilayer wiring board according to any one of claims 1 to 5. 7. The method according to claim 1, wherein an outer layer material is laminated via a prepreg on the inner layer material reduced in an ionizing atmosphere, and then laminated and bonded in the ionizing atmosphere. 3. The method for producing a multilayer wiring board according to item 1.