JP2001123298A - Electroplating method, multi-layered printed circuit board and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the electroplating at a constant electrolytic current density, and to reduce the dispersion in the thickness of a deposited film of a plating metal even when the area of individual works to be plated is scattered. SOLUTION: The relationship between the electrode potential and the current density is obtained in advance using electrodes formed of the same material as that of a work to be plated, the work to be plated is polarized at an arbitrary electric potential or current value in a plating bath, the current or the electric potential in this condition is obtained, the area of the work to be plated is calculated from the relationship and the current and the electric potential, and the electroplating is performed at a current to achieve the plating of a predetermined film thickness according to on this calculated area.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrolytic plating method mainly for use in forming wiring in the production of electronic components such as a multilayer wiring board, a method for manufacturing a multilayer wiring board using this method, and a method for producing the same. The present invention relates to a multilayer wiring board.

[0002] The multilayer wiring board in the present invention includes both a package board (for example, a plastic package board) accommodating a semiconductor element and a multilayer printed wiring board for mounting such a package product. .

[0003] For convenience of explanation, in the following description, a multilayer copper wiring board is taken as an example of a multilayer wiring board and electrolytic copper plating is taken as an example of electrolytic plating. However, electrolytic plating and wiring are not limited to copper.

[0004]

2. Description of the Related Art Conventionally, general-purpose semiconductor devices have been often mass-produced in a small number of types, but recently, ASICs have been widely used.
Developed for a specific application, called "products", is increasing in the variety of small-lot production. Therefore, many types of wiring boards for connecting these semiconductor elements are required.

[0005] Also, the rate of technological progress in the electronics field in recent years is remarkably high, and design changes to provide higher performance are frequently performed. From these points, it is desired that the wiring board manufacturing technology be able to flexibly cope with high-mix low-volume production and frequent design changes.

On the other hand, with the rapid progress of electronic equipment, multi-layer printed wiring boards and plastic packages used for housing and connecting semiconductor elements are becoming increasingly finer and more highly integrated as well as products. Improvements in reliability, durability and product homogeneity are required.

For example, in a conventional package product, the wiring width is relatively large at 50 μm, but at present, the wiring width is 35 μm.
m or less are manufactured. However, when a wiring pattern is manufactured by a photoresist technique using a plating resist, an error of about 2 μm may occur in the width of the wiring formed by the resist pattern due to a settling of a developing solution or a timing shift during exposure and development. It is inevitable that it will come out. When the wiring width is large like the conventional product,
This error can be ignored, but as described above, the wiring width is 35 μm.
When it becomes smaller than the following, the error in the wiring width becomes an error in the area to be plated, which greatly affects the uniformity of the product.

That is, if wiring is formed under the same electrolytic plating conditions on a substrate having a variation in the area of an exposed portion to be plated (a portion not protected by the resist), a substrate having a large exposed area can be formed. Plating is deposited thickly on a substrate having a small plating thickness and a small exposed area.
Such variations in the plating film thickness (wiring thickness) may degrade the electrical characteristics of the product and cause waste of materials.

Therefore, in order to stably produce a product capable of reliably meeting the above-mentioned strict requirements for a multilayer wiring board having a small wiring width, even if the wiring width fluctuates to some extent, the wiring thickness may be reduced. Strict control of the manufacturing process is essential so that the error of the process becomes small.

In manufacturing a multilayer wiring board having a small wiring width and a relatively high degree of integration, a manufacturing process called a semi-additive process is generally used. In this process, an insulating resin layer is formed on a substrate provided with a base wiring layer, and the surface of the resin is subjected to a roughening treatment to form an electroless copper plating film. After forming a resist pattern for wiring formation using a plating resist thereon, electrolytic copper plating is performed using the electroless copper plating layer as a power supply layer. Copper deposition by electrolysis does not occur in the part protected by the plating resist, and copper electrolysis and deposition proceeds selectively only in the part where the electroless copper plating layer is exposed, and the copper having a required thickness is formed. A wiring pattern is formed. Thereafter, the plating resist is peeled off, and the electroless copper plating layer protected by the plating resist is dissolved and removed by a quick etching process, whereby an independent wiring is formed.

In the above-described semi-additive process,
Electroless copper plating is only deposited on the very thin film necessary to secure a power supply layer for electrolytic copper plating, and copper wiring with the required thickness is essentially formed using electrolytic plating technology. You. In electrolytic plating, as known by Faraday's law, the amount of metal deposited on a given electrode surface is proportional to the product of current density and electrolysis time. Therefore, when the current density is constant, it is possible to obtain a metal deposition film having a stable film thickness by giving an electrolytic plating time sufficient to obtain a desired film thickness, and it is easy to control the thickness of the copper wiring. This is because electrolytic plating requires less cost.

[0012]

However, the surface to be plated of the substrate on which electrolytic plating is performed in the semi-additive process is a portion patterned by a plating resist.
(Exposed part not covered with plating resist).
As described above, since the wiring width of the resist pattern is inevitably about 2 μm in error, the area of this exposed portion, that is, the electrode area at the time of electrolytic plating, has some variation depending on the individual and the production lot. The smaller the wiring width, the greater the influence of this variation on the plating thickness.

Even if the variation in the area of the exposed portion of the substrate in the previous process is so small as to be negligible, not only when the plating object is different as described above but also when the design is changed, the electrode area is not changed. Fluctuates.

Further, in an actual electrolytic plating tank, in order to eliminate variations in current distribution and to achieve a uniform deposition film thickness, there is a direct relationship with a product called a dummy electrode in the vicinity of an object to be plated. The installation of a non-existent cathode is often performed, but the deposition of the plating metal on such a dummy electrode changes the cathode area, and consequently the overall electrode area also changes.

Such a change in the electrode area is caused by
Give electrolytic current density according to electrolytic plating chance,
Alternatively, unless the necessary electroplating time is given, this may cause a variation in the deposited metal film thickness.

However, since there is no suitable method for easily and accurately grasping the electrode area, the following method has conventionally been adopted as a means capable of coping with such a change in the electrode area. In other words, the amount of deposition per unit time is calculated by performing electrolytic plating at a specific current value for a specific time on some of the substrates on which the electrolytic plating process is performed, and measuring the amount of the deposition. Then, by dividing the desired amount of deposition by this value, the electrolytic plating time is determined.

Such a technique is not easy to use, and the substrate used for calculating the amount of deposition cannot be used as a final product, but also requires a long time for electrolytic plating on each of the objects to be plated. It does not give.

An object of the present invention is to provide a method for easily and accurately calculating an electrode area of an object to be plated in an electrolytic plating step, so that an electrolytic plating is always performed at a constant electrolytic current density. It is an object of the present invention to develop a technology which makes it possible to easily deposit a plating metal on an object to be plated. More specifically, an object of the present invention is to develop an efficient and simple manufacturing technique for a multilayer wiring board having fine wiring with reduced variation in wiring thickness.

[0019]

Means for Solving the Problems The present inventors have noticed that, under specific conditions, a specific one-to-one relationship exists between the activation energy of the reaction and the electrolytic current in an electrochemical reaction. The present inventors have completed a study on a method for easily grasping the electrode area of the object to be plated using this relationship.

That is, if the solution conditions and the stirring conditions are constant, a stable one-to-one correlation between the electrode potential and the electrolytic current density is recognized. Therefore, the relationship between the electrode potential and the electrolytic current density is investigated using an electrode having a known area made of substantially the same material as the object to be plated. On the other hand, an object to be plated is subjected to constant potential polarization to a specific electrode potential in a plating bath, and a current value at that time is measured. At this time, the relationship between the polarization potential and the current density is equal to the relationship between the electrode potential and the current density investigated using an electrode having a known area. Dividing by the density gives the electrode area of the object to be plated.

By multiplying the electrode area obtained in this way by a predetermined predetermined electrolytic current density, the total current value to be energized is determined. By performing electrolytic plating at a current value determined by such a method, it becomes possible to perform electrolytic plating with a constant and accurate value of the current density in all products.

The electrolytic plating method of the present invention comprises the following steps (1) to
(1) a step of obtaining a current value and a potential value at the time of polarization of an object to be plated in a plating bath; (2) from a material substantially the same as the object to be plated From the relationship between the electrode potential and the current density obtained using an electrode having a known area, and the current value and the potential value obtained in the step (1),
(3) calculating a current value at which the current density of the object to be plated becomes any desired value from the calculated area value; and (4) A step of energizing the object to be plated with the current value calculated in the step (3) to deposit a plated metal;

The method of manufacturing a multilayer wiring board according to the present invention is a method of manufacturing a multilayer wiring board in which at least a part of the wiring is formed by electrolytic plating.
(1) A step of obtaining a current value and a potential value at the time of polarization of the portion to be plated in a plating bath with respect to the underlying substrate having the portion to be plated exposed. (2) the relationship between the electrode potential and the current density obtained using an electrode having a known area composed of substantially the same material as the portion to be plated, and the current value and the potential value obtained in the step (1). From
Calculating the area of the portion to be plated of the substrate; (3) calculating a current value at which the current density of the portion to be plated becomes any desired value from the calculated area value; and (4) A step of applying a current to the portion to be plated with the current value calculated in the step (3) to deposit a plating metal and form a wiring.

According to the present invention, there is provided a multilayer wiring board having wiring between resin layers, wherein the width of the wiring is 35 μm or less, and at least a part of the wiring is formed by electrolytic plating. A multilayer wiring board is also provided, wherein the standard deviation of the film thickness of the wiring formed by electroplating the substrate is 2.8% or less.

[0025]

Embodiments of the present invention will be described with reference to the accompanying drawings. In the present invention, using an electrode having a known electrode area, made of substantially the same material as the object to be plated, preferably under the same plating conditions as the plating conditions for the object to be plated , The relationship between the electrode potential E (V) and the electrolytic current density i (A / m ² ) is determined in advance. As long as the difference can be adjusted by the correction, a slight difference in the plating condition is allowed.

Obtaining the relationship between the two may be obtaining the electrolytic current density for a specific electrode potential.
It may be to obtain a relational expression with each electrolytic current density when the electrode potential changes.

As a means for obtaining such a relationship between the two, a normal polarization measurement method can be used, and a potential regulation method for measuring the electrolytic current while controlling the electrode potential, and an electrode potential method while controlling the current. The current regulation method that measures the current can be used. In the measurement using the potential regulation method, any of the constant potential polarization method and the potentiodynamic polarization method can be adopted.

In the following description, the potential regulation method will be described, but the basic operation is the same even if the current regulation method is used.

FIG. 1 shows an example of a cathode polarization curve showing the relationship between the electrode potential E (V) and the current density i (A / m ² ) obtained as described above. Of course, the current density when a predetermined electrode potential x (V) is applied may be measured individually. At this time, the electrode potential at the time of polarization in the plating bath to be described later and the electrode potential x (V) are set to the same value. In the present invention including both of these cases, the "relationship" between the electrode potential and the current density is simply obtained.

A reference electrode is required for measuring the electrode potential. If the electrode shows a stable potential in the same plating solution, a known reference electrode such as a silver / silver chloride reference electrode or a saturated calomel reference electrode can be used. Either can be used. Since a certain amount of cupric ion is present in the electrolytic plating solution, if a metal piece such as copper or platinum naturally immersed exhibits a stable natural electrode potential, use this as a reference electrode. Is also possible.

Separately, an object to be plated whose area is unknown is placed in a plating bath, and the above-described specific electrode potential is set.
The potential is polarized at [x (V)], and the current value [y (A)] at that time is measured. That is, the relationship between the electrode potential and the current value obtained in advance is reproduced in an actual plating bath, the current value [y (A)] at that time is obtained, and the current density value [z (A / m ² )]
Compare with.

In the present invention, the electrode potential for performing the constant potential polarization is not particularly limited as long as it is substantially the same as the previously determined electrode potential in the above-described relationship, but it is possible to measure the current with the required accuracy. If so, for the following reasons:
Specifically, it is desirable to select the electrode potential so that the measured current value is as small as possible.

That is, when the polarization overpotential indicated by the difference between the natural electrode potential and the polarization potential is relatively small, the reaction rate is relatively small, and the influence of the concentration overpotential caused by the delay of mass transport can be neglected. The speed does not depend on the flowing state of the plating solution. At this time, the relationship between the polarization overvoltage and the current density is mainly determined by the activation energy of the reaction, and a one-to-one relationship is established between the electrode potential and the electrolytic current density.

However, when the polarization overpotential is relatively large, the reaction speed is high, and the supply of the reactive species sufficient for the reaction tends to be delayed, so that the influence of mass transport is increased. In such a state, the correspondence between the electrode potential and the electrolytic current density changes depending on the flow conditions of the plating solution. In order to utilize the relationship between the electrode potential and the electrolytic current density under such circumstances, it is necessary to completely match the flow conditions. However, it is practically extremely difficult to stabilize the flow conditions industrially. is there.

Further, by performing the constant potential polarization, metal deposition occurs in accordance with the current density on the object to be plated, which is a product itself, so that the flow of a large current is stable at a constant current density. It is not preferable from the viewpoint of the present invention that the plating is to be performed.

Next, according to the present invention, the object to be plated is determined by utilizing the relationship between the electrode potential and the current density obtained by using the electrode having the known area as described above, for example, their polarization curves. When reading the value [z (A / m ² )] of the electrolytic current density at the potential [x (V)] polarized at a constant potential, or when applying the electrode potential [x (V)] determined as such. Next, the electrolytic current density [z (A / m ² )] is measured.

On the other hand, the electrolytic current density of the plating object subjected to the constant potential polarization is equal to the electrolytic current density read from the above-mentioned polarization curve or actually measured at the same electrode potential. The electrode area of the object to be plated (area to be plated) [S (m ² )] is calculated by dividing the current value measured during polarization of the object by the electrolytic current density. This relational expression is represented by y ÷ z = S (1)

Once the electrode area (S) of the object to be plated has been determined, the electrode area is multiplied by any desired electrolytic current density to immediately give an electrolytic current value to be added from now on. Electroplating with a constant electrolytic current density on the object is always possible.

By incorporating such a system in advance in an electrolytic plating apparatus, electrolytic plating at a constant electrolytic current density can be performed more easily.

The electrolytic plating method according to the present invention can be applied to plating operations in general, but it is particularly difficult to determine the area to be plated in advance, and the plating method requires plating of a certain thickness. It is advantageous to apply the present invention to electrolytic plating of an object or electrolytic plating in which the properties of a deposited film greatly change depending on the electrolytic current density.

When a dummy electrode (dummy substrate) is used for the purpose of making the distribution of the deposited film thickness uniform on one substrate, the calculated electrode area value is determined by the exposed area of the wiring portion and the dummy area. The present invention can be applied without any problem since it is given by the total sum with the electrode area. Rather, when the dummy electrode is used, the effect of the area increase accompanying the metal deposition on the electrode is definitely present, and this variation factor is excluded by the present invention, so that the effect is enormous.

It is particularly advantageous to apply the present invention to an electrolytic plating method used for forming wiring in the production of a multilayer wiring board, for example. In this case, copper wiring is formed by performing electrolytic plating on the underlying substrate (for example, an unfinished package on which the underlying wiring layer is formed) where the plating target portion is exposed, as follows. can do.

That is, as described above, the relationship between the electrode potential and the current density is obtained in advance by using an electrode having a known area made of substantially the same material as the portion to be plated. On the other hand, for an underlying substrate (eg, an unfinished package) where the portion to be plated is exposed, the electrode potential and current value when polarized in a plating bath with a preset electrode potential are determined. The current value obtained at this time is compared with the current density obtained by the above-described relationship, and the area of the exposed portion to be plated of the substrate is obtained by the above-mentioned relational expression (1). From the area of the portion to be plated, a current value for obtaining an arbitrary desired plating thickness at a specific current density is calculated, plating is performed by applying the calculated current value,
The wiring is formed by depositing a metal having a desired thickness.

The electroplating conditions after the exposed area of the substrate to be plated, that is, the area of the portion to be plated is determined, are well known to those skilled in the art, and need not be described further. Would.

According to the present invention, the wiring width of the wiring board is 35
μm or less, preferably 30 μm or less, and even when the influence on the plating thickness due to the variation in the wiring width becomes relatively large, the exposed area, that is, the area of the portion to be plated can always be measured, and the calculation is performed based on that. By performing the plating operation with the set current value, it is possible to form a wiring having a predetermined thickness and a uniform thickness.

In particular, by setting the standard deviation of the film thickness to 2.8% or less for such variations in the wiring thickness, excellent effects such as stable driving at a high frequency, which cannot be obtained conventionally, can be obtained. This is realized, and the practical significance of such a multilayer wiring board according to the present invention is great.

Although the present invention has been described with reference to the case where the plating type is copper, the plating type is nickel, gold,
The effect of the present invention can be similarly achieved as long as a deposition film can be obtained by electrolytic plating, such as another metal such as silver or zinc, or an alloy of these metals. For example, in the case of electrolytic pattern plating of an Fe-Ni alloy used for a magnetic head or the like, the composition of the deposited film changes depending on the current density, so that the present invention can be effectively used.

[0048]

EXAMPLES The function and effect of the present invention will be described more specifically with reference to examples, but the present invention is not limited only to the embodiments. First, the relationship between the electrode potential of electrolytic plated copper and the electrolytic current density in a sulfuric acid-copper sulfate plating bath is determined. Table 1 shows an outline of the bath composition of the electrolytic copper plating bath used.

[0049]

[Table 1]

For the measurement, a rotating disk electrode device (manufactured by Nikkatsu Keiso; RRDE-1), a speed controller (manufactured by the company;
SC-5), capacity 0.15 dm ³ of a glass cell (manufactured by the company; NKC-70-
T) and a platinum rotating disk electrode (manufactured by the company; NDE-1-6: electrode area = 2.826 × 10 ⁻⁵ m ² ). For the platinum rotating disk electrode, immediately before the measurement, using a copper sulfate plating solution,
Disk rotational speed 900 rpm, at a current density of 100A / m ² 600
s was previously subjected to electrolytic copper plating. A platinum electrode is used as a counter electrode, and a double junction silver / silver chloride reference electrode (3.0 kmol / m ³ -KCl) is used as a reference electrode (Iwaki Glass Co., Ltd .; IW06)
7] was used.

For the electrochemical measurement, a fully automatic polarization measuring device was used.
[HZ-1A, potentiometer / galvanostat; HA-501G, arbitrary function generator; HB-105, manufactured by Hokuto Denko; PC-9801Ra, manufactured by NEC Corporation] were used. The measurement was performed at a potential sweep rate of 0.5 mV from the natural electrode potential toward the cathode.
/ s. FIG. 2 shows the disk rotation speed in this example.
The polarization curve measured at 400 rpm is shown.

Next, an object to be plated actually subjected to electrolytic plating will be described. A commercially available copper-clad laminate (epoxy, FR-4 grade) was used as the base substrate, and the base circuit was formed on the copper foil on the surface using an etching solution containing a ferric chloride aqueous solution as a main component.

As the insulating material, a phenol novolak type epoxy resin (manufactured by liquefied shell, trade name: Epicoat 15)
A varnish containing 4) as a main component was prepared, and the varnish was applied on the above substrate by a roll coating method, and dried and cured at 423 K for 10.8 k seconds to form an insulating resin layer.

The thickness of the insulating resin layer after drying and curing is 35 μm.
Met. After performing the swelling treatment on the resin surface, potassium permanganate (60 g / dm ³ ) and sodium hydroxide (35 g / dm ³
Roughening treatment was performed by dipping in a mixed solution containing ³ ) as a main component at 353 K for 720 seconds. Thereafter, the roughened insulating resin surface was subjected to a neutralization treatment, and a curing treatment was performed at 448 K for 3.6 ksec.

A palladium catalyst is applied to the surface of the resin after the roughening treatment.
(Manufactured by Shipley Co., Ltd.), and after activation treatment, metal copper deposition treatment by electroless plating for 1.2 ksec was performed using a 323 K electroless copper plating bath shown in Table 2. The film thickness of the copper deposited by this electroless copper plating process was 0.8 μm.

[0056]

[Table 2]

Next, a wiring pattern was formed by photolithography using a photosensitive plating resist. At this time, the width of the wiring pattern (the exposed portion to be plated) was 35 μm. The undersubstrates, which are the objects to be plated, processed in this way were prepared for each of the examples and comparative examples of the present invention, and each of the substrates was subjected to electrolytic plating.

The exposed portion that is not protected by the photosensitive plating resist, that is, the area of the electrode to be plated is desired because there is an individual difference for each substrate and the area of each electrode is unknown. It is difficult to perform stable electrolytic plating at a current density, and as a result, this causes a variation in the wiring film thickness.

FIG. 3 schematically shows an electrolytic plating apparatus used in this example, a processed substrate which is an object to be plated, and an arrangement of a reference electrode and a counter electrode, which are installed in an electrolytic plating tank. In this example, a phosphorus-containing copper plate that is usually used was used for the counter electrode, and a copper piece was used for the reference electrode.

That is, a copper sulfate plating bath 2 is accommodated in the electrolytic plating bath 1, and a substrate 3 to be plated as a working electrode and a copper piece 5 as a reference electrode are arranged in the plating bath so as to face each other. In the meantime, a phosphorus-containing copper plate 4 is used as a counter electrode.
Is installed. Each electrode is connected to a bridge 6 which is a probe, and connected to a DC stable power supply 8 via a switch 7 and to a potentiostatic polarization device 9 including an ammeter. Will be

It is desirable that the reference electrode 4 be placed as close as possible to the substrate 3 to be plated, which is the working electrode, in order to avoid a potential drop caused by the solution resistance. The reference electrode was placed at a position 5 mm away from the working electrode because of its excellent conductivity (62 S / m) and relatively low polarization voltage and relatively low current density.

For the constant potential polarization, a fully automatic polarization device controlled by the personal computer 10 was used.
The set potential is 50 times higher than the natural electrode potential of copper as the reference electrode.
The potential was mV lower. The current value measured at this time is
0.2869 to 0.28, depending on each individual substrate 3 to be plated
Varied between 92 A.

From the polarization curve shown in FIG. 2, the potential was -50 mV.
vs. E _{corr of Cu} = 0.4 mVvs. Ag / AgCl (3.0 kmol / m ³ -KCl)
In this case, the electrolytic current density obtained from the copper electrode is 4.712 A / m ² , so that the electrolytic current density in the portion to be plated of the substrate is also determined to be 4.712 A / m ² .

Assuming that the current value measured at this time is 0.2880 A, the area of the portion to be plated (exposed electrode) of the substrate is 0.06112 m ² , and the electrolytic current density is 50 A / m ² . In order to carry out the electrolytic plating, it is immediately found that the electrolytic plating should be carried out at a total current of 3.056 A.

In this embodiment, a constant-potential polarization device 9, a system for calculating the electrode area by the above-described calculation to determine the total current value, and a DC stable power supply for performing electrolytic plating for a predetermined time at the total current value The total current was adjusted between 3.044 and 3.069 A using an electroplating apparatus equipped with an electroplating apparatus as described above. In all electrolytic plating, the electrolytic plating time was 10.8 ks, and the target film thickness was 18 μm.

As described above, according to the present invention, the electrode area of each substrate to be plated is calculated, and the total current is increased or decreased so that the electrolytic current density becomes a constant value. Are shown in Table 3. This table also shows, as a comparative example, the standard deviation of the deposited film thickness in the wiring portion when the test was performed with the total current fixed at 3.057 A. Since the standard deviation was reduced by 20% from 3.5% in the comparative example to 2.8% in the present invention example, it was confirmed that the wiring thickness between products was uniform, and stable operation at high frequency was achieved in all products. There is expected.

In each of the examples of the present invention and the comparative examples, 128
Electroplating was performed on one substrate, and the thickness of each deposited film was measured by observing a substrate, which had been cut and polished with its cross section embedded and polished, using an optical microscope.

[0068]

[Table 3]

From Table 3, it is confirmed that the use of the present invention reduces the variation in the thickness of the deposited film. In the above comparative example, the same wiring board was used. However, when the wiring pattern is different, the effect of the present invention is as follows.
It will be even bigger.

[0070]

According to the present invention, electrolytic plating at a constant electrolytic current density can be easily performed, and a multilayer wiring board having a very uniform thickness of a deposited metal film can be easily manufactured.

[Brief description of the drawings]

FIG. 1 is a graph showing a measurement result of a cathode polarization curve.

FIG. 2 is a graph showing a polarization curve measured at a copper rotating disk electrode at a disk rotating speed of 400 rpm.

FIG. 3 is a schematic explanatory view of an electrolytic plating apparatus for performing the electrolytic plating of the present invention.

[Explanation of symbols]

 1: Electrolytic plating tank 2: Copper sulfate plating solution 3: Substrate to be plated (working electrode) 4: Copper piece (reference electrode) 5: Phosphorus-containing copper plate (counter electrode) 6: Bridge (probe) 7: Switching device 8: DC Stable power supply 9: Constant potential polarizer (including ammeter) 10: Personal computer for control

Claims (3)

[Claims] 1. An electrolytic plating method including the following steps (1) to (4): (1) a step of obtaining a current value and a potential value at the time of polarization of an object to be plated in a plating bath; From the relationship between the electrode potential and the current density obtained using an electrode having a known area composed of substantially the same material as the object, and the current value and the potential value obtained in the step (1),
(3) calculating a current value at which the current density of the object to be plated becomes any desired value from the calculated area value; and (4) A step of energizing the object to be plated with the current value calculated in the step (3) to deposit a plated metal; 2. A method for producing a multilayer wiring board in which at least a part of wiring is formed by an electrolytic plating method, wherein the electrolytic plating method includes the following steps (1) to (4):
Method for manufacturing multilayer wiring board: (1) Step of obtaining current value and potential value at the time of polarization of a portion to be plated, in a plating bath, for an underlying substrate having a portion to be plated exposed; (2) Part to be plated From the relationship between the electrode potential and the current density obtained using an electrode having a known area made of substantially the same material, and from the current value and the potential value obtained in the step (1),
Calculating the area of the portion to be plated of the substrate; (3) calculating a current value at which the current density of the portion to be plated becomes any desired value from the calculated area value; and (4) A step of applying a current to the portion to be plated with the current value calculated in the step (3) to deposit a plating metal and form a wiring. 3. A multilayer wiring board having wirings between resin layers, wherein the width of the wirings is 35 μm or less, at least a part of the wirings is formed by electrolytic plating, A multilayer wiring board, wherein a standard deviation of a film thickness of wiring formed by electrolytic plating is 2.8% or less.