JP2003183857A - Etchant and method for manufacturing circuit board therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an etchant for optionally setting dissolution rates for two different metals, and a method for manufacturing a circuit board therewith. <P>SOLUTION: The etchant includes monovalent copper ions, divalent copper ions, and hydrochloric acid, wherein the mole fraction of the monovalent copper ions to the total copper ions is 0.1 or more, and the monovalent copper ions have the saturated concentration thereof or lower. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an etching solution and a method for manufacturing a circuit board using the same.

[0002]

2. Description of the Related Art Conventionally, a circuit board has been formed by etching using a copper clad laminate in which a paper base phenol resin or a glass base epoxy resin and a copper foil are laminated.
Along with the multifunctionalization and high performance of electronic devices, circuit boards mounted on the electronic devices have been diversified, and various manufacturing methods thereof have been proposed.

For example, there is a metal core substrate in which a low thermal expansion metal such as 42 alloy is arranged in a circuit substrate for the purpose of mounting a semiconductor element. This aims to match the coefficient of thermal expansion of the entire circuit board with the coefficient of thermal expansion of silicon of the semiconductor element by utilizing the low coefficient of thermal expansion of the metal serving as the core.

Further, as a suspension assembly for supporting a magnetic head of a magnetic disk device, a stainless steel substrate serving as a suspension and a circuit for transmitting a signal to the magnetic head are integrated via an insulating resin layer,
There is a so-called metal base substrate.

Usually, metals such as copper, copper alloys, silver and gold having good electric conductivity are used for the circuit of the circuit board.
Copper or copper alloy is mainly used in terms of cost.

Both the metal core substrate and the metal base substrate have the same structure in which a metal other than copper or a copper alloy is laminated on the circuit, and are circuit substrates which take advantage of the characteristics of the metal serving as the core or the base.

In general, the core or base metal is electrically isolated from the circuit, but it may be used as a part of the circuit. In this case, in order to improve electric conductivity and thermal conductivity, a composite material is used in which a core or base metal is used as a core material, and copper or copper alloy is clad on one or both surfaces of the core material.

This copper or copper alloy is manufactured by depositing it by plating, sputtering or the like, or by mechanically forming a clad. Further, in order to secure the adhesiveness between the copper or the copper alloy and the core material, an adhesive layer of nickel or nickel alloy, palladium, chromium or the like may be interposed.

One of the methods of manufacturing a metal base substrate is as follows. FIG. 7 is a schematic cross-sectional view showing a manufacturing process of a metal base substrate according to a conventional technique, in which a conductive layer 23 made of copper or a copper alloy is formed on a metal foil 21 serving as a base via an insulating resin layer 22 (FIG. 7). (A)). Specifically, after applying the varnish-shaped insulating resin layer 22 to the metal foil 21, the conductive layer 23 is deposited by plating, sputtering or the like, or a sheet in which the insulating resin layer 22 and the conductive layer 23 are laminated in advance. Is adhered to the metal foil 21 by laminating or the like.

The conductive layer 23 is formed by plating or sputtering.
In the case of forming the conductive layer 23, the via hole 24 may be formed in the insulating resin layer 22 in advance by a dry process method such as laser or plasma, a photolithography method, or the like (FIG. 7B). .

Next, the conductive layer 23 is etched to form the circuit 2.
After forming 5, the metal foil 21 is etched to form the support plate 26, which becomes the metal base substrate 27 (FIG. 7).
(C)).

Further, in the method of manufacturing a circuit board, a transfer board having a circuit layer or an insulating resin layer formed on a support and a separately prepared double-sided board or transfer board are laminated and bonded through an adhesive, a prepreg or the like. After that, there is a transfer method in which the support is peeled off. As this support, a plate or foil of alloy such as stainless steel or 42 alloy, nickel, copper, copper alloy is used, and stainless steel is preferable from the viewpoint of handleability.

As the method for peeling the support, there are a mechanical peeling method and a method of dissolving and removing by etching.

As a method for mechanically peeling off, for example, according to Japanese Patent Laid-Open No. 11-17300, two transfer substrates each having a circuit layer formed by copper plating on a stainless support are bonded with an adhesive, a prepreg, or the like. After laminating and adhering via, the support is peeled off.

In the method of dissolving and removing by etching,
Use an etching solution that dissolves the support and has a sufficiently slow circuit dissolution rate, or insert a metal that serves as an etching barrier between the support and the circuit to dissolve and remove the support, and then remove another The etching barrier is dissolved and removed with an etching solution. In the method of dissolving and removing by etching,
Since a part of the support can be selectively peeled off, the support can be used as a reinforcing plate or a circuit.

As described above, the iron-nickel alloy such as 42 alloy, the iron-nickel chromium alloy such as stainless steel, and the iron-chromium alloy have been used for a part of the circuit board or used in the manufacturing process.

[0017]

However, the copper (II) chloride etching solution and the iron (II) chloride etching solution used as general etching solutions have different dissolution rates depending on the type of metal. That is, in the manufacturing method of the metal base substrate, it is necessary to perform the step of etching the conductive layer to form the circuit and the step of etching the metal foil to form the support in separate steps. Therefore, it is necessary to change the temperature of the etching solution or the processing time, or to change the type of the etching solution, which complicates the process and lowers the yield.

When simultaneously etching with a single etching solution, it is necessary to make the ratio of the dissolution rate of the metal foil and the circuit to the etching solution and the ratio of the thickness of the metal foil and the circuit similar to each other. It is difficult to freely set the thickness of the metal foil and the thickness of the circuit.

When a composite material is used for the metal foil serving as the core or the base, when a common etching solution is used for etching, a difference in the dissolution rate of each metal of the composite material causes a step difference near each metal interface. FIG. 8 is a schematic cross-sectional view showing a cross-sectional shape when the melting rate of the core material 29 is higher than that of the clad metal 28, and thus, a step is formed in the cross-sectional shape of both of them.

Further, in the transfer method, it is difficult to control the adhesion between the support and the circuit layer or the insulating resin layer by the method of mechanically peeling off the support. This may cause peeling failure or transfer failure. On the other hand, if the adhesion is too low, the circuit layer or the insulating resin layer may be separated from the support during the manufacturing process, which may cause defects.

In the method of dissolving and removing by etching,
A practical etching solution that dissolves the support and dissolves the circuit sufficiently slowly is required, but when the circuit is copper or copper alloy, the only metal that can be used as the support is nickel or nickel alloy. . That is, the present situation is that the etching that dissolves 42 alloy or stainless steel and that the dissolution rate of copper or copper alloy is sufficiently slow has not yet been put to practical use.

In view of the above, an object of the present invention is to provide an etching solution capable of arbitrarily setting the dissolution rates of two different metals.

Another object of the present invention is to provide a method of manufacturing a circuit board which can be manufactured at low cost by using the above etching solution.

[0024]

The gist of the present invention for achieving the above object is as follows. An etching solution containing monovalent copper ions, divalent copper ions, and hydrochloric acid, wherein the monovalent copper ions have a mole fraction (hereinafter, Cu ⁺ /
(Referred to as Cu) is 0.1 or more and the concentration of monovalent copper ions is below the saturation concentration.

In the etching solution of the present invention, when Cu ⁺ / Cu increases, the dissolution rate of metals such as copper, copper alloys, nickel, nickel alloys, iron nickel alloys, iron chromium alloys and iron nickel chromium alloys decreases.

At this time, although it depends on the total copper ion concentration and the hydrochloric acid concentration, the reduction rate of the dissolution rate is different for each metal. That is,
The ratio of the dissolution rates of two metals selected from the above alloys, that is, the ratio of the dissolution rate of the first metal divided by the dissolution rate of the second metal (hereinafter referred to as V1 / V2) is the above etching rate. It can be changed depending on Cu ⁺ / Cu of the liquid.

When Cu ⁺ / Cu is in the range of approximately 0.1 to 0.6, V1 / V2 can be changed to approximately 0.5 to 2. That is, the thickness of the first metal can be set to about 0.5 to 2 times the thickness of the second metal.

Further, when the composite material is etched by using an etchant having V1 / V2 of about 1, no step is formed in the cross-sectional shape as shown in FIG. 8, and the interface between the first metal and the second metal is not formed. The neighborhood can be finished to be almost smooth.
When the adhesion layer is interposed between the first metal and the second metal, the thickness of the adhesion layer is preferably as thin as possible.

When Cu ⁺ / Cu exceeds 0.6, V1 / V
2 further increases, more than doubles. In particular, when the second metal is copper or a copper alloy, if Cu ⁺ / Cu increases to the saturation concentration of the monovalent copper ions of the etching solution of the present invention,
Almost no metal is dissolved. That is, the etching solution of the present invention is an etching solution that dissolves the first metal and has a sufficiently slow dissolution rate of the second metal, and also as a stripping solution for the first metal on the second metal. It is possible to use.

In the method of manufacturing a circuit board by the transfer method,
Even if a metal serving as a barrier is not present, it is possible to remove the first metal serving as a support by etching without excessive erosion of copper or copper alloy that serves as a circuit. Therefore, in addition to nickel or a nickel alloy, an iron-nickel alloy such as 42 alloy or permalloy, an iron-chromium alloy such as SUS430, or an iron-nickel-chromium alloy such as SUS304 or SUS316 can be selected for the support.

The total copper ion and hydrochloric acid concentrations of the etching solution of the present invention may be set according to the types of the first metal and the second metal. However, in order to obtain a practical dissolution rate, it is preferable that the total copper ions are in the range of 0.2 to 3.0 mol / L and the hydrochloric acid is in the range of 50 to 400 ml / L.

The saturation concentration of monovalent copper ions varies depending on the concentration of all copper ions, the concentration of hydrochloric acid, and the liquid temperature, so that the saturation concentration cannot be unconditionally shown. The method for preparing the etching solution of the present invention is preferably a method of dissolving and diluting copper (II) chloride or its hydrate, copper (I) chloride and hydrochloric acid with water.

Further, copper (II) chloride or its hydrate and hydrochloric acid are dissolved and diluted with water, and then a metal such as copper, iron or nickel, or an alloy such as 42 alloy or stainless steel is dissolved to obtain a monovalent metal. Copper ions may be generated. Further, copper oxide or copper hydroxide may be used instead of copper chloride.

[0034]

[Equation 1]

T = W × t / 2 ... [1] Obtain each etching amount with respect to the immersion time of 1, 2 and 3 minutes, plot the horizontal axis as the immersion time and the vertical axis as the etching amount, and plot the slope of the primary approximation line. The dissolution rate was used. When the smut after etching adhered, it was treated with a smut removing solution (50 ml / L-hydrochloric acid) at a solution temperature of 40 ° C. for 2 minutes to remove the smut, and then the weight change rate was obtained.

The etching solutions used in the examples and comparative examples are copper (II) chloride dihydrate (manufactured by Wako Pure Chemical Industries, Ltd .: special grade reagent), copper chloride (I) (Wako Pure Chemical Industries, Ltd.). Made by:
Special grade reagent), hydrochloric acid (manufactured by Wako Pure Chemical Industries, Ltd .: special grade reagent, 3
5-37%). The concentration of monovalent copper ions was determined by a redox titration method using a 0.02 mol / L-potassium permanganate solution (manufactured by Wako Pure Chemical Industries, Ltd .: for volumetric analysis).

[Example 1] In this example, the dissolution rates of the first metal and the second metal when Cu ⁺ / Cu was changed while keeping the total copper ion concentration and the hydrochloric acid concentration constant were obtained. .

SUS304 foil (made by Toyo Seifu Co., Ltd .: SUS304BA) was selected as the first metal, and electrolytic copper foil (GP-35 manufactured by Nippon Denki Co., Ltd.) was selected as the second metal, and the total copper ions were 1.2 mol /. With respect to an etching solution containing L and hydrochloric acid of 250 ml / L, the dissolution rate of each metal was determined within a range of Cu ⁺ / Cu of about 0.1 to about 0.5. The result is shown in FIG.

FIG. 1 is a graph showing the relationship between Cu ⁺ / Cu and the dissolution rate of SUS304 foil and electrolytic copper foil. C
When u ⁺ / Cu is in the range of about 0.1 to about 0.3, the dissolution rate of the second metal is faster than that of the first metal, and Cu ⁺ /
Cu was about 0.3, and became almost the same. And Cu ⁺ / C
When u further increases, the dissolution rates of both are reversed and the second
The dissolution rate of the first metal was higher than that of the above metal.

[Embodiment 2] In this embodiment, a first metal, which is actually a base, and a second metal, which is a circuit, are laminated with an insulating resin interposed therebetween. The first metal and the second metal were simultaneously etched by using the metal base substrate.

In this embodiment, the first metal and the second metal have the same thickness (about 25 μm). Hereinafter, description will be given with reference to schematic cross-sectional views of the manufacturing process of the circuit board in FIG.

First, a 25 μm thick SUS304 foil (TOYO SEIFO CO., LTD .: SUS304BA) was cut into a desired size, and a degreasing agent at 60 ° C. (Daiichi Kogyo Seiyaku Co., Ltd .: 50 ml / L) was cut.
-Methacryl CL-5513) for 2 minutes, washed with water, and then roughened at 60 ° C (250 ml / L-hydrochloric acid, 50 m
1 / L-nitric acid) for 3 minutes to roughen the surface, wash with water and dry to prepare a base 1 (FIG. 2 (a)).

Next, a polyamic acid resin solution having the following composition was coated on one surface of the base 1 (SUS304) by a spin coater, dried in a drying oven at 100 ° C. for 15 minutes, and then 400
The insulating resin layer 2 made of polyimide and having a thickness of about 30 μm was formed by curing for 1 hour in a drying oven in a nitrogen gas atmosphere at ℃ (FIG. 2B).

Polyamic acid resin composition Acid anhydride: 3,3 ′, 4,4′-biphenyltetracarboxylic acid 5 parts by weight Diamine: p-phenylenediamine 5 parts by weight Solvent: N-methyl-2-pyrrolidone 28 parts by weight Next In addition, the surface of the insulating resin layer 2 is treated with a desmearing agent (Meltex: MLB-497) at 70 ° C. for 5 minutes to roughen the surface, and after washing with water, a neutralizing agent at 60 ° C. (Meltex: ML: ML).
B-790) for 5 minutes and washed with water. Furthermore, 25 ℃
Plating catalyst (manufactured by Hitachi Chemical Co., Ltd .: HS-202B) for 5 minutes, washed with water, and then treated with an activation solution at 25 ° C. (ADP-601 manufactured by Hitachi Chemical Co., Ltd.) for 5 minutes, and then washed with water.
It was dried to deposit the plating catalyst.

Then, the activation solution at 25 ° C. (100 ml /
It is treated with L-sulfuric acid) for 30 seconds, washed with water, immersed in electroless copper plating (CUST-2000 manufactured by Hitachi Chemical Co., Ltd.) at 40 ° C. for 10 minutes, washed with water and dried to obtain an electroless material of about 0.2 μm. A copper plating layer was formed on the surface of the insulating resin layer 2.

Next, the activation solution at 25 ° C. (100 ml / L
-Sulfuric acid) for 20 seconds, followed by washing with water, and then using a copper sulfate plating solution (manufactured by Nikko Metal Plating Co., Ltd .: 0.2 ml / L-CC-1220) at 25 ° C on the electroless copper plating layer. Copper plating was performed at a current density of 0.5 A / dm ² for 50 minutes, washed with water, and dried in a drying oven at 100 ° C. for 30 minutes to form a copper plating layer 3 having a thickness of about 25 μm (FIG. 2).
(C)).

Then, a dry film resist (SPG-152 manufactured by Asahi Kasei Kogyo KK) was laminated on both sides at 110 ° C., a film mask was adhered thereto, and ultraviolet rays were irradiated at 120 mJ / cm ² using an ultrahigh pressure mercury lamp, and 30 ° C. Of the developer (10 g / L-sodium carbonate) was sprayed at a pressure of 0.1 MPa for 20 seconds, washed with water and dried,
An etching resist layer 4 was formed (FIG. 2 (d)).

Next, 1.2 mol of all copper ions at 50 ° C.
/ L, hydrochloric acid is 250 ml / L, Cu ⁺ / Cu is 0.31 and the etching solution is sprayed at a pressure of 0.15 MPa for 45 seconds, then washed with water, and a resist stripping solution (3
After spraying 0 g / L-sodium hydroxide) at a pressure of 0.1 MPa for 30 seconds to remove the dry film resist, it was washed with water and dried to produce a metal base substrate 5 having a circuit with a thickness of about 25 μm (FIG. 2 (e)).

When the metal base substrate 5 was observed from both sides, both the circuit and the base were good without any defects such as excessive thinning or etching residue.

[Embodiment 3] In this embodiment, the thickness of the second metal is reduced to about 15 μm by shortening the copper sulfate plating time to 30 minutes.
And change the etching solution Cu ⁺ / Cu to 0.43
A metal base substrate was produced in the same manner as in Example 2 except that Therefore, the metal base substrate of this embodiment has a metal thickness of about 25 μm for the first metal and about 15 μm for the second metal.

When the above metal base substrate was observed from both sides, both the circuit and the base were good, without defects such as excessive thinning or etching residue.

[Embodiment 4] In this embodiment, all copper ions are 1.5 mol / L, hydrochloric acid is 200 ml / L, and Cu ⁺ / Cu.
For the etching solution of 0.34, 42 alloy foil (Sumitomo Special Metals Co., Ltd .: D-1) is selected as the first metal, and electrolytic copper foil (Nippon Electrolytics Co., Ltd .: GP-35) is selected as the second metal. The dissolution rate of each metal was determined. As a result, the dissolution rate of the 42 alloy foil was 0.37 μm / min, and the dissolution rate of the copper alloy foil was 0.38 μm / min, which were almost the same.

Example 5 In this example, a metal core substrate having a composite material in the core was produced by using the etching solution used in Example 4. 3A to 3D are schematic cross-sectional views showing the manufacturing process of the circuit board of this embodiment.

First, 42 alloy foil with a thickness of 50 μm (D-1 manufactured by Sumitomo Special Metals Co., Ltd.) was cut into a desired size and 42
A metal base substrate 5 made of an alloy material was prepared (Fig. 3
(A)).

Next, a degreasing agent at 60 ° C. (Daiichi Kogyo Seiyaku Co., Ltd.)
Made: 50 ml / L-methacryl CL-5513) for 2 minutes
After rinsing with water and rinsing with water, 40 ° C activation solution (330ml / L
-Hydrochloric acid) for 1 minute. After washing this with water, sulfuric acid at 25 ° C
Copper plating solution (manufactured by Nikko Metal Plating Co., Ltd .: additive
0.2 ml / L-CC-1220) and 2.5 A / d
m ²Copper plating is performed for 10 minutes at the current density of 1 and after washing with water, 1
Dry in a drying oven at 00 ° C for 30 minutes to obtain copper with a thickness of about 5 μm.
The plating layer 6 is formed to form the metal base substrate 1
A composite material 7 in which copper was clad on one side of a roy material was produced.
(FIG.3 (b)).

Then, a polyamic acid resin solution having the same composition as in Example 2 was spin-coated on the surface of the 42 alloy material side,
After drying in a drying oven at 100 ° C. for 15 minutes, it was cured in a drying oven in a nitrogen gas atmosphere at 400 ° C. for 1 hour to form an insulating resin layer 8 of polyimide having a thickness of about 20 μm (FIG. 3 (c)).

Next, a dry film resist (SPG-152 manufactured by Asahi Kasei Kogyo Co., Ltd.) is formed on the copper plating layer 6 side at 110 ° C.
The film mask is closely adhered to the film mask, irradiated with ultraviolet rays of an ultra-high pressure mercury lamp at 120 mJ / cm ² , sprayed with a developer (10 g / L-sodium carbonate) at 30 ° C. at a pressure of 0.1 MPa for 20 seconds, and then washed with water. Then, it was dried to form an etching resist layer 9 (FIG. 3D).

Next, 1.5 mol of all copper ions at 50 ° C.
/ L, hydrochloric acid 200 ml / L, Cu ⁺ / Cu 0.34 etching solution was sprayed for 90 seconds at a pressure of 0.15 MPa. This was washed with water, a resist stripping solution at 40 ° C. (30 g / L-sodium hydroxide) was sprayed at a pressure of 0.1 MPa for 30 seconds to strip the dry film resist, washed with water, and then dried (FIG. 3 (e )).

Next, the same polyamic acid resin solution as in Example 2 was spin-coated on the surface of the composite material side, dried at 100 ° C. for 15 minutes in a drying furnace, and then dried in a drying furnace at 400 ° C. in a nitrogen gas atmosphere. By curing for a time, an insulating resin layer 10 made of polyimide having a thickness of about 20 μm was formed (FIG. 3).
(F)).

Further, on the surface on the insulating resin layer 10 side, using a laser hole punching device (MODEL 5200 manufactured by ESI), frequency 4 kHz, output 700 mW, 50 shots /
Under the conditions of holes, a via hole 11 having a diameter of about 50 μm and a through hole 12 having a diameter of about 90 μm were formed (FIG. 3).
(G)).

Next, a desmearing agent (MLB-497, manufactured by Meltex) at 70 ° C. is applied for 5 minutes to roughen the surface, and after washing with water, a neutralizing agent (MLB-79, manufactured by Meltex: 60 ° C.) is used.
It was treated with 0) for 5 minutes and washed with water. Furthermore, it was treated with a plating catalyst (manufactured by Hitachi Chemical Co., Ltd .: HS-202B) at 25 ° C. for 5 minutes, washed with water, and then activated at 25 ° C. (manufactured by Hitachi Chemical Co., Ltd .:
After being treated with ADP-601) for 5 minutes, it was washed with water and dried to deposit a plating catalyst.

Then, the activation solution at 25 ° C. (100 ml /
L-sulfuric acid) for 30 seconds, washed with water, immersed in electroless copper plating (CUST-2000 manufactured by Hitachi Chemical Co., Ltd.) at 40 ° C. for 10 minutes, washed with water and dried to a thickness of about 0.2 μm. Electrolytic copper plating was formed on both sides.

Next, an activation solution (100 ° C.) at 25 ° C. at 25 ° C.
2.5 A / using a sulfuric acid copper plating solution (manufactured by Nikko Metal Plating Co., Ltd .: additive 0.2 ml / L-CC-1220) at 25 ° C. for 20 seconds.
Copper plating was performed at a current density of dm ² for 50 minutes. This was washed with water and dried in a drying oven at 100 ° C. for 30 minutes to form a copper plating layer 13 having a thickness of about 25 μm (FIG. 3 (h)).

Then, a dry film resist (SPG-152 manufactured by Asahi Kasei Kogyo Co., Ltd.) is laminated on both sides at 110 ° C., a film mask is brought into close contact with the film, ultraviolet rays of an ultra-high pressure mercury lamp are irradiated at 120 mJ / cm ² , and development is carried out at 30 ° C. The liquid (10 g / L-sodium carbonate) was sprayed at a pressure of 0.1 MPa for 20 seconds and then washed with water.

Further, a copper (II) chloride etching solution (2 mol / L-copper (II) chloride dihydrate, 100 ml at 50 ° C.)
/ L-hydrochloric acid) was sprayed at a pressure of 0.15 MPa for 30 seconds and then washed with water, and a resist stripping solution (30 g /
L-sodium hydroxide) is sprayed at a pressure of 0.1 MPa for 30 seconds to remove the dry film resist,
A circuit was formed by washing with water and drying, and a metal core substrate 14 having a composite material composed of copper and 42 alloy as a core was produced (FIG. 3 (i)).

When the cross section of the produced metal core substrate 14 was observed, the vicinity of the interface between the copper and the 42 alloy of the core was almost smooth and had a good shape.

[Embodiment 6] This embodiment is similar to Embodiment 1 except that the total copper ion concentration and the hydrochloric acid concentration are kept constant.
The dissolution rates of the first metal and the second metal when ⁺ / Cu was changed were determined.

With respect to an etching solution having a total copper ion concentration of 2.36 mol / L and hydrochloric acid of 100 ml / L, Cu ⁺ /
Cu is in the range of about 0.3 to about 0.75, and SUS304 foil (manufactured by Toyo Seifoil Co., Ltd .; SUS304B) is used as the first metal.
A) dissolution rate (V1), and dissolution rate (V of electrolytic copper foil (Nippon Electrolytic Co., Ltd .: GP-35)) as the second metal (V).
2) was calculated. Figure 4 shows Cu ⁺ / Cu and dissolution rate ratio V1 /
It is a graph which shows the relationship of V2.

When Cu + / Cu exceeds 0.6, V1 / V
2 became 3 or more, and when Cu ⁺ / Cu exceeded 0.7, V1 / V2 became 7 or more. That is, it was found that the etching solution of the present invention can be used as an etching solution that dissolves the first metal and has a sufficiently slow dissolution rate of the second metal.

[Embodiment 7] This embodiment is similar to Embodiment 1 except that the total copper ion concentration and the hydrochloric acid concentration are kept constant.
The dissolution rates of the first metal and the second metal when ⁺ / Cu was changed were obtained.

Total copper ion concentration was 1.5 mol / L, hydrochloric acid was 300 ml / L, Cu ⁺ / Cu was in the range of about 0.6 to about 1.1, and 42 alloy foil (Sumitomo Sumitomo) was used as the first metal. The dissolution rate (V1) manufactured by Special Metals Co., Ltd. and the dissolution rate (V2) of an electrolytic copper foil (GP-35 manufactured by Nippon Denshoku Co., Ltd.) as the second metal were determined.

FIG. 5 shows C of 42 alloy foil and electrolytic copper foil.
7 is a graph showing the relationship between u ⁺ / Cu and the dissolution rate ratio V1 / V2. When Cu ⁺ / Cu was 1.0 or more, V1 / V2 was 3 or more, and when Cu ⁺ / Cu was 1.1 or more, V1 / V2 was 8 or more. That is, it was found that the etching solution of the present invention can be used as an etching solution which dissolves the first metal and dissolves the second metal at a sufficiently slow rate, as in Example 6.

[Embodiment 8] In this embodiment, the total copper ion concentration is 1.5 mol / L, the hydrochloric acid is 300 ml / L, and Cu ⁺ /
The dissolution rate of 36 alloy foil (Sumitomo Special Metals Co., Ltd .: I) and copper alloy foil (Yamaha Ohrin Metals Co., Ltd .: OLIN7025) was determined using an etching solution having Cu of 1.06.

As a result, the dissolution rate of the 36 alloy foil was 0.
It was found that the dissolution rate of the copper alloy foil was 35 μm / min, the dissolution rate of the copper alloy foil was 0.06 μm / min, and the dissolution rate of the copper alloy foil was sufficiently slower than that of the 36 alloy foil.

[Embodiment 9] In this embodiment, the total copper ion concentration is 1.5 mol / L, the hydrochloric acid is 300 ml / L, and Cu ⁺ /
Using an etching solution with Cu of 1.05, the dissolution rate of nickel foil (Toyo Seifuku Co., Ltd .: Ni-H) and electrolytic copper foil (Nihon Denryoku Co., Ltd .: GP-35) was determined.

As a result, the dissolution rate of the nickel foil was 0.4.
It was found that the dissolution rate of the electrolytic copper foil was 1 μm / min and the dissolution rate of the electrolytic copper foil was 0.05 μm / min, which was sufficiently slower than that of the nickel foil.

[Embodiment 10] In this embodiment, a circuit board is manufactured by a transfer method using the etching liquid of the embodiment 6, and FIG. 6 is a schematic sectional view showing a manufacturing process of the circuit board. .

First, a 50 μm thick SUS304 foil (manufactured by Nippon Steel Co., Ltd .: SUS304BA) was cut into a desired size, and a degreasing agent at 60 ° C. (manufactured by Daiichi Kogyo Seiyaku Co., Ltd .: 50 ml /
After treatment with L-methacryl CL-5513) for 2 minutes and washing with water, a surface roughening solution (250 ml / L-hydrochloric acid, 50 m) at 60 ° C.
(1 / L-nitric acid) for 3 minutes for roughening, washing with water and drying to prepare a support 15 (FIG. 6 (a)).

Next, on one surface of the support 15, a dry film resist (SPG-152 manufactured by Asahi Kasei Kogyo KK) was used.
Laminate at ℃, adhere a film mask, irradiate with ultraviolet rays of ultra-high pressure mercury lamp at 120 mJ / cm ^2, and apply 30 MPa developer (10 g / L-sodium carbonate) at 0.1 MPa.
After spraying for 20 seconds under the pressure of, the product was washed with water.

Further, the activation solution at 40 ° C. (330 ml / L
-Treated with hydrochloric acid for 1 minute, washed with water, and then a copper sulfate plating solution at 25 ° C (manufactured by Nikko Metal Plating Co., Ltd .: additive 0.2 m)
1 / L-CC-1220), and copper plating was performed for 20 minutes at a current density of 2.5 A / dm ² .

Then, after washing with water, a resist stripping solution (30 g / L-sodium hydroxide) at 40 ° C. is sprayed at a pressure of 0.1 MPa for 30 seconds to strip the dry film resist, followed by washing with water and drying to about 10 μm. Thick first circuit 1
6 was formed (FIG. 6 (b)).

Next, the second embodiment is formed on the surface on the first circuit 16 side.
A solution of a polyamic acid resin having the same composition as the above was spin-coated, dried in a drying oven at 100 ° C. for 15 minutes, and then cured in a drying oven in a nitrogen gas atmosphere at 400 ° C. for 1 hour to give a thickness of about 3
An insulating resin layer 17 made of 0 μm polyimide was formed (FIG. 6C).

Next, a laser hole punching device (manufactured by ESI:
MODEL 5200) with a frequency of 4 kHz, an output of 700 mW, and a diameter of about 50 μm under the conditions of 50 shots / hole.
Via hole 18 was formed (FIG. 6D).

Next, a desmearing agent (MLB-497, manufactured by Meltex) at 70 ° C. is applied for 5 minutes to roughen the surface, and after washing with water, a neutralizing agent (MLB-79, manufactured by Meltex: 60 ° C.) is used.
It was treated with 0) for 5 minutes and washed with water. Furthermore, it was treated with a plating catalyst (manufactured by Hitachi Chemical Co., Ltd .: HS-202B) at 25 ° C. for 5 minutes, washed with water, and then activated at 25 ° C. (manufactured by Hitachi Chemical Co., Ltd .:
After being treated with ADP-601) for 5 minutes, it was washed with water and dried to deposit a plating catalyst.

Then, the activation solution at 25 ° C. (100 ml /
L-sulfuric acid) for 30 seconds, washed with water, immersed in electroless copper plating (CUST-2000 manufactured by Hitachi Chemical Co., Ltd.) at 40 ° C. for 10 minutes, washed with water and dried to a thickness of about 0.2 μm. An electrolytic copper plating layer was formed on the surface of the insulating resin layer.

Next, the electroless copper plating layer was immersed in an activating liquid (100 ml / L-sulfuric acid) at 25 ° C. for 20 seconds, washed with water, and then a copper sulfate plating liquid at 25 ° C. (manufactured by Nikko Metal Plating Co., Ltd.). : Additive 0.2 ml / L-CC-1120) was used for copper plating at a current density of ² A / dm ² for 30 minutes, followed by washing with water and drying in a drying oven at 100 ° C. for 30 minutes.

Next, a dry film resist (SPG-152, manufactured by Asahi Kasei Kogyo Co., Ltd.) was laminated on the copper-plated surface at 110 ° C., a film mask was brought into close contact, and ultraviolet rays were irradiated at 120 mJ / cm ² with an ultra-high pressure mercury lamp, After spraying a developing solution (10 g / L-sodium carbonate) at 30 ° C. for 20 seconds at a pressure of 0.1 MPa, washing with water and iron (II) chloride etching solution at 50 ° C. (42 Baume) at a pressure of 0.1 MPa. After spraying for 60 seconds, it was washed with water.

Further, a resist stripping solution at 40 ° C. (30 g /
L-sodium hydroxide) was sprayed at a pressure of 0.1 MPa for 30 seconds to remove the dry film resist, washed with water, and dried to form a second circuit 19 having a thickness of about 15 μm (FIG. 6 (e)). )).

Next, on the surface of the support, total copper ions at 50 ° C. were 2.36 mol / L, hydrochloric acid was 100 ml / L, and Cu ⁺ / C.
Etching solution with u of 0.68 is applied at a pressure of 0.1 MPa
After being processed for a minute, the support 15 was peeled off, washed with water and dried to fabricate the circuit board 20 by the transfer method (FIG. 6 (f)).

When the section of the circuit board 20 was observed, it was confirmed that the first circuit 16 was formed without any abnormality.

Comparative Example 1 In this comparative example, the dissolution rate was similarly obtained using an etching solution having the same total copper ion concentration and hydrochloric acid concentration as in Example 7, but containing almost no monovalent copper ions.

42 alloy foil (manufactured by Sumitomo Metals Co., Ltd .: D-1) and electrolytic copper using an etching solution having a total copper ion concentration of 1.5 mol / L, hydrochloric acid of 300 ml / L, and Cu ⁺ / Cu of 0. The dissolution rate of the foil (manufactured by Nippon Denki Co., Ltd .: GP-35) was determined. As a result, the dissolution rate of 42 alloy foil is 2.1.
The dissolution rate of the electrolytic copper foil was 1.45 μm / min. Therefore, in the transfer method, it is difficult to remove 42 alloy without a barrier layer by etching.

Comparative Example 2 In this comparative example, a circuit board was produced in the same manner as in Example 10, except that an etching solution containing almost no monovalent copper ions was used in the step of peeling the support 15. .

First, the steps of preparing the support of Example 10 (FIG. 6A) to the step of forming the second circuit (FIG. 6E) were performed in the same manner.

Next, on the surface of the support, total copper ions at 50 ° C. were 2.36 mol / L, hydrochloric acid was 100 ml / L, and Cu ⁺ / C.
A circuit board was produced by a transfer method in which an etching solution having u of 0 was used for treatment at a pressure of 0.1 MPa for 45 seconds to remove the support, followed by washing with water and drying.

Observation of the cross section of the above circuit board revealed that
The first circuit was corroded by the etching solution, and a part of the circuit was missing. Therefore, it is found that it is difficult to remove SUS304 by etching without the barrier layer in the transfer method.

[0096]

By using the etching solution of the present invention, the dissolution rate of two kinds of metals can be set arbitrarily. Further, if a circuit board is produced using the etching solution of the present invention, it is possible to simultaneously etch two kinds of metals.

In the transfer method, the support can be removed by etching without the barrier layer, and the circuit board can be provided at low cost.

[Brief description of drawings]

FIG. 1 C of SUS304 foil and electrolytic copper foil of Example 1
⁶ is a graph showing the relationship between u ⁺ / Cu and the dissolution rate.

2A to 2D are schematic cross-sectional views showing a manufacturing process of a circuit board of Example 2.

3A to 3D are schematic cross-sectional views showing a manufacturing process of a circuit board of Example 5.

FIG. 4 C of SUS304 foil and electrolytic copper foil of Example 6
⁶ is a graph showing the relationship between u ⁺ / Cu and the dissolution rate ratio (V1 / V2).

FIG. 5: Cu of 42 alloy foil and electrolytic copper foil of Example 7
⁴ is a graph showing a relationship between ⁺ / Cu and a dissolution rate ratio (V1 / V2).

FIG. 6 is a schematic cross-sectional view showing the manufacturing process of the circuit board of Example 10;

FIG. 7 is a schematic cross-sectional view showing a manufacturing process of a metal base substrate according to a conventional technique.

FIG. 8 is a schematic cross-sectional view showing a cross-sectional shape when the melting rate of the core material is faster than that of the clad metal according to the conventional technique.

[Explanation of symbols]

1 ... Base, 2, 10, 22 ... Insulating resin layer, 3, 6, 1
3 ... Copper plating layer, 4, 9 ... Etching resist layer, 5,
27 ... Metal base substrate, 7 ... Composite material, 11, 18, 2
4 ... Via hole, 12 ... Through hole, 8, 10, 1
7, 30 ... Insulating resin layer, 14 ... Metal core substrate, 15 ...
Support, 16 ... First circuit, 19 ... Second circuit, 20 ...
Circuit board, 21 ... Metal foil, 23 ... Conductive layer, 25 ... Circuit,
26 ... Support plate, 28 ... Clad metal, 29 ... Core material.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kazumi Fujii             7-1-1, Omika-cho, Hitachi-shi, Ibaraki Prefecture             Inside the Hitachi Research Laboratory, Hitachi Ltd. (72) Inventor Daisuke Usanda             1-2 1-2 Shimohozumi, Ibaraki City, Osaka Prefecture Nitto             Electric Works Co., Ltd. F-term (reference) 4K057 WA10 WB02 WB03 WB04 WB08                       WB11 WB15 WE08 WG03 WN01                 5E339 AB02 BC01 BC02 BE13 CC01                       CC02 CD01 CE11 CE14 CE16                       CF16 CF17 CG04 DD04 GG10

Claims (7)

[Claims] 1. An etching solution containing monovalent copper ions, divalent copper ions and hydrochloric acid, wherein the monovalent copper ions have a molar fraction of 0.1 or more with respect to all the copper ions, and the monovalent copper ions. An etching solution having a saturation concentration of less than or equal to. 2. An etching solution containing monovalent copper ions, divalent copper ions and hydrochloric acid, wherein the monovalent copper ions are in a molar fraction of 0.1 to 0.6 with respect to the total copper ions. Etching solution. 3. The total copper ions are 0.2 to 3.0 mol / L.
And hydrochloric acid is 50 to 400 ml / L.
Or the etching solution according to 2. 4. A method for producing a circuit board having a structure having a first metal and a second metal, which comprises monovalent copper ions, divalent copper ions and hydrochloric acid, and the monovalent copper ions are all copper ions. On the other hand, the circuit board is characterized in that the first metal and the second metal are simultaneously etched using an etching solution having a molar fraction of 0.1 or more and a saturation concentration of monovalent copper ions or less. Manufacturing method. 5. A method for producing a circuit board having a structure having a first metal and a second metal, which comprises monovalent copper ions, divalent copper ions and hydrochloric acid, and the monovalent copper ions are all copper ions. On the other hand, a method for producing a circuit board, which comprises simultaneously etching the first metal and the second metal using an etching solution having a molar fraction of 0.1 to 0.6. 6. The first metal and the second metal of the circuit board are different metals, and the metal is made of copper, copper alloy, nickel, nickel alloy, iron nickel alloy, iron chromium alloy, iron nickel chromium alloy. The method for producing a circuit board according to claim 4, wherein the metal is selected. 7. The first metal of the circuit board is nickel,
Any one of nickel alloy, iron-nickel alloy, iron-chromium alloy, iron-nickel-chromium alloy, the second of the circuit board
The method for manufacturing a circuit board according to claim 4, wherein the metal is copper or a copper alloy.