CN1324164C - Copper or copper alloy corrodent and corrosion method - Google Patents

Abstract

The present invention provides an etching agent for copper or a copper alloy, which consists of an aqueous solution containing hydroxyl amine, an oxidizer, ammonium salt, and an azole compound, for smoothening the surface of copper under a mild condition.

Description

Etchant and corrosion method for copper or copper alloy

technical field

The present invention relates to an etchant and an etching method capable of corroding the surface of copper or copper alloy (hereinafter simply referred to as 'copper') to be smooth.

Background technique

As an etchant capable of forming a smooth copper surface, for example, JP-A-58-21028 discloses an acidic aqueous solution containing oxalate, hydrogen peroxide, amines, and benzotriazole. Furthermore, US Pat. No. 5,630,950 specification discloses an acidic aqueous solution containing sulfuric acid, hydrogen peroxide, and a hydrogen peroxide stabilizer.

However, the etchant disclosed in Japanese Patent Laid-Open No. 58-21028 has problems in that it must be treated at a high temperature of 50° C., and insoluble copper complexes tend to precipitate. In addition, the etchant disclosed in US Pat. No. 5,630,950 has problems such as the need to control the concentration of sulfuric acid or hydrogen peroxide within a narrow range, and sudden boiling is likely to occur when the concentration of hydrogen peroxide is too high.

Contents of the invention

Therefore, in order to solve the disadvantages of the prior art, it is an object of the present invention to provide an etchant for smoothing copper surfaces and an etching method for smoothing the above-mentioned surfaces under mild conditions.

In order to solve the above-mentioned problems, the present inventors have repeatedly studied and found that if the copper surface is brought into contact with an aqueous solution containing hydroxylamine, an oxidizing agent, an ammonium salt and an azole compound, the copper surface can be smoothed.

That is, the present invention is accomplished by the following constitutions.

(1) An etchant for copper or copper alloys composed of an aqueous solution containing hydroxylamine, an oxidizing agent, an ammonium salt, and an azole compound.

(2) An etching method in which an aqueous solution containing hydroxylamine, an oxidizing agent, an ammonium salt, and an azole compound is brought into contact with the surface of copper or copper alloy to smooth the surface.

Detailed ways

Next, the present invention will be described in detail.

The hydroxylamine used in the present invention keeps the solution alkaline, suppresses the decomposition of the oxidant, and keeps copper in the solution. Specific examples thereof include monoethanolamine, N-methylethanolamine, N- Monoethanolamines such as ethylethanolamine, N-butylethanolamine, N,N-dimethylethanolamine, N,N-diethylethanolamine, 2-(2-hydroxy)ethoxyethanolamine, diethanolamine, N- Diethanolamines such as methyldiethanolamine and N-butyldiethanolamine, alkanolamines such as triethanolamine, propanolamine, isopropanolamine, and hydroxyethylpiperazine, or an aqueous ammonia solution.

Among the above-mentioned hydroxylamines, alkanolamines having 8 or less carbon atoms such as monoethanolamine, diethanolamine, and triethanolamine, or aqueous ammonia solutions are preferable in terms of high ability to retain copper, easy availability, and low cost. The above-mentioned hydroxylamines may be used in combination of two or more.

The concentration of hydroxylamine in the etchant is preferably 1-40% (weight%, the same applies hereinafter), more preferably 5-30%.

In the case of the above-mentioned concentration of 1-40%, the amount of copper that can be dissolved in the etching solution is large, and the oxidizing agent is difficult to decompose, and it is also preferable in terms of cost.

The oxidizing agent used in the present invention is a component for oxidizing copper and promoting its dissolution into a solution. Specific examples thereof include, for example, chloric acid, chlorate (sodium salt, potassium salt, etc.), Chlorous acid, chlorite (sodium salt, potassium salt, etc.), hypochlorous acid, hypochlorite (sodium salt, potassium salt, etc.) Among the above-mentioned oxidants, chlorate, chlorite, hypochlorite, etc. Salts such as chlorate because of their high stability in solution. The above-mentioned oxidizing agents may be used in combination of two or more.

The concentration of the oxidizing agent in the etchant is preferably 1-15%, more preferably 5-10%.

In the case of the above-mentioned solution being 1-15%, the corrosion rate can be accelerated, and the oxidizing agent itself is difficult to decompose, and it is also preferable in terms of cost.

The ammonium salt used in the present invention is a component that promotes the dissolution of copper by supplying ammonium ions to the solution. Specific examples thereof include ammonium chloride, ammonium bromide, ammonium sulfate, ammonium persulfate, Ammonium sulfamate, ammonium oxalate, monoammonium phosphate, diammonium phosphate, triammonium phosphate, ammonium citrate, diammonium citrate, ammonium adipate, ammonium lactate.

Among the above-mentioned ammonium salts, ammonium chloride, ammonium bromide, ammonium sulfate, monoammonium phosphate, diammonium phosphate, triammonium phosphate, ammonium citrate. The aforementioned ammonium salts may be used in combination of two or more.

The concentration of the ammonium salt in the etchant is preferably 1 to 10%, more preferably 2 to 6%. When the above-mentioned concentration is 1-10%, the corrosion rate is neither too fast nor too slow, which is relatively moderate. Therefore, it will not cause uneven depth, and it is easy to obtain a smooth copper surface.

The azole compound used in the present invention is a component that suppresses the dissolution of copper in the vertical direction and promotes the dissolution of copper in the horizontal direction. Specific examples thereof include imidazole, 2-phenylimidazole, 1-ethylene Imidazoles such as imidazole, benzimidazole, 2-butylbenzimidazole, 2-phenethylbenzimidazole, 2-aminobenzimidazole, 2-mercaptobenzimidazole, and 1,2,4-triazole , 3-amino-1,2,4-triazole, 1,2,3-benzotriazole, 1-hydroxybenzotriazole, carboxybenzotriazole, etc. triazoles, tetrazole, 5- Tetrazoles such as phenyl-1H-tetrazole, 5-methyl-1H-tetrazole, and 5-amino-1H-tetrazole, pyrimide, benzothiazole, 2-mercaptobenzothiazole, and the like.

Among the above-mentioned azole compounds, imidazole, 1-vinylimidazole, 1,2,4-triazole, 3-amino-1,2,4-triazole, 1-hydroxybenzotriazole, tetrazole, 5 - Azole compounds without an aromatic substituent such as methyl-1H-tetrazole and 5-amino-1H-tetrazole, because they are easily soluble in a solution and have a good effect of smoothing the copper surface. The above-mentioned azole compounds may be used in combination of two or more.

The concentration of the azole compound in the etchant is preferably 0.1 to 2%, more preferably 0.4 to 1.2%. When the above-mentioned concentration is 0.1 to 2%, it is easy to obtain a smooth copper surface.

The corrosive agent of the present invention is alkaline, and its pH value is usually in the range of 10-12.

Various additives may also be added to the etchant of the present invention. For example, a surfactant may be added to make the etchant more uniform.

The etchant of the present invention can be easily adjusted by dissolving the above-mentioned components in water. The above-mentioned water is preferably water from which ionic substances and impurities have been removed, such as ion-exchanged water.

There is no particular limitation on the copper surface to be treated with the etchant of the present invention, for example, it may be the surface of copper foil, electroless copper plating, electrolytic copper plating, copper sprayed coating, and the like. For the above-mentioned copper surface, a clean surface that has been subjected to alkali cleaning with an aqueous sodium hydroxide solution or the like, or acid cleaning with sulfuric acid or hydrochloric acid is preferable.

As a method of bringing the etchant of the present invention into contact with the copper surface, for example, a spray method, a shower method, a dipping method, etc. can be used, followed by washing with water and drying.

The conditions for bringing the etchant into contact with the copper surface are not particularly limited, but usually the temperature of the etchant is preferably 20 to 30° C., and the contact time is preferably 30 to 120 seconds.

In addition, the preferred range of the amount of corrosion (corrosion depth) varies depending on the surface state of the copper surface or the target smoothness, but is usually 1 to 4 μm.

If the etchant of the present invention is used to corrode the copper surface, the smoothness of the copper surface can be improved as the corrosion progresses. Therefore, when the unevenness of the surface to be treated is large, or when a smooth surface is desired, the amount of etching (etching depth) can be increased.

As described above, by using the etchant of the present invention to etch the copper surface, the copper surface can be etched smoothly. The etchant of the present invention is beneficial to the pretreatment of metal plating such as nickel plating, gold plating, silver plating, tin plating, etc., and can improve the smoothness of metal plating. In addition, it is also advantageous for the pretreatment of pasting photoresist when forming the copper circuit pattern of the printed circuit board, etc. by the photolithography method.

【Example】

Embodiment 1～6 and comparative example 1～2

The components shown in Table 1 were mixed to prepare an etchant.

Next, the copper-clad laminate for printed circuit boards was immersed in a 5% hydrochloric acid aqueous solution for 15 seconds, washed with water, and dried to clean the copper surface. At 25° C., the etchant shown in Table 1 below was sprayed for 30 seconds to etch 2 μm, and then washed with water and dried. Also, the value of the amount of corrosion was calculated from the weight, surface area, and specific gravity of dissolved copper.

The smoothness of the treated copper surface was evaluated by glossiness.

Gloss is obtained by using a portable gloss meter PG-1M manufactured by Nippon Denshoku Kogyo Co., Ltd., and measuring 20-degree specular gloss according to JIS Z 8741. The results are shown in Table 1.

Comparative example 1

In the same manner as in Example 1, an etchant was prepared and etched, but the copper surface was hardly corroded. Table 1 shows the glossiness of the obtained surface.

Comparative example 2

As in Example 1, an etchant was prepared and the copper surface was etched. Table 1 shows the glossiness of the obtained surface.

【Table 1】 Example number Composition (weight%) Gloss 1 Diethanolamine 10 sodium hypochlorite 10 ammonium sulfate 61-vinylimidazole 0.8 ion-exchanged water 73.2 82.0 2 Monoethanolamine 6 sodium hypochlorite 10 ammonium sulfate 51-vinylimidazole 0.8 ion-exchanged water 78.2 76.5 3 Diethanolamine 10 Sodium hypochlorite 10 Ammonium citrate 61-Vinylimidazole 0.6 Ion-exchanged water 73.4 91.3 4 Diethanolamine 10 sodium hypochlorite 10 ammonium sulfate 5 benzimidazole 1 ion-exchanged water 74 83.4 5 Monoethanolamine 15 sodium chlorate 15 ammonium chloride 4 benzimidazole 1 ion-exchanged water 65 89.6 6 Monoethanolamine 10 sodium chlorate 15 ammonium sulfate 55-methyl-1H-tetrazole 1.2 ion-exchanged water 68.8 87.9 Comparative example 1 Diethanolamine 10 sodium hypochlorite 101-vinylimidazole 0.8 ion-exchanged water 79.2 24.4 Comparative example 2 Diethanolamine 10 sodium hypochlorite 10 ammonium sulfate 6 ion-exchanged water 74 6.3

As shown in Table 1, by using the etchant of the present invention, the copper surface can be etched to a smooth surface having a glossiness of 76.6 or higher.

The present invention can provide an etchant for smoothing the copper surface under mild conditions and an etching method for smoothing the above-mentioned surface.

Claims (2)

1. A corrosion agent for copper or copper alloy, characterized in that: by containing 1 to 40% by weight selected from monoethanolamine, N-methylethanolamine, N-ethylethanolamine, N-butylethanolamine, N, N- Dimethylethanolamine, N,N-diethylethanolamine, 2-(2-hydroxy)ethoxyethanolamine, diethanolamine, N-methyldiethanolamine, N-butyldiethanolamine, triethanolamine, propanolamine, At least one of alkanolamine and ammonia solution composed of isopropanolamine and hydroxyethylpiperazine, 1-15% by weight of oxidizing agent, 1-10% by weight of ammonium salt and 0.1-2% by weight of azole compound in aqueous solution The oxidizing agent is at least one selected from chloric acid, chlorate, chlorous acid, chlorite, hypochlorous acid and hypochlorite. 2. A method for corroding copper or copper alloys, characterized in that: 1 to 40% by weight is selected from monoethanolamine, N-methylethanolamine, N-ethylethanolamine, N-butylethanolamine, N, N -Dimethylethanolamine, N,N-diethylethanolamine, 2-(2-hydroxy)ethoxyethanolamine, diethanolamine, N-methyldiethanolamine, N-butyldiethanolamine, triethanolamine, propanolamine At least one of alkanolamine and ammonia solution composed of isopropanolamine and hydroxyethylpiperazine, 1 to 15% by weight of oxidant, 1 to 10% by weight of ammonium salt and 0.1 to 2% by weight of the aqueous solution of azole compound and The surface contact of copper or copper alloy, and make described surface smooth; Described oxidizing agent is at least one selected from chloric acid, chlorate, chlorous acid, chlorite, hypochlorous acid and hypochlorite .