KR101462286B1 - Etching Solution - Google Patents

Abstract

[PROBLEMS] To provide a nickel etching solution capable of suppressing erosion of metals other than nickel, particularly copper.

[MEANS FOR SOLVING THE PROBLEMS] The present invention relates to an etching solution comprising a polymer having at least one repeating unit selected from the following general formulas (I), (II) and (III), in a nickel etching solution containing nitric acid or sulfuric acid, hydrogen peroxide and water will be.

(I)

≪

(III)

Wherein R ₁ to R ₅ are independently selected from the group consisting of hydrogen, amino, imino, cyano, azo, thiol, sulfo, hydroxyl, carbonyl, And the amine contained in the repeating unit may be in the form of a quaternary ammonium salt.

Nickel etching solution, nickel coating, electrolytic plating, hydrogen peroxide, copper etching

Description

Etching Solution

The present invention relates to a nickel etchant comprising nitric acid or sulfuric acid, hydrogen peroxide and water.

In the production of electrodes and wirings of a printed circuit board including a flexible substrate for TAB (Tape Automated Bonding) or a substrate for a BGA (Ball Grid Array) package, or electrodes of semiconductor products, electroplating or electroless plating is used to form a nickel film Is formed. At this time, the nickel film formed on the unnecessary portion is removed by the etching solution.

Since the electrode and the wiring are made of a plurality of metals, when the nickel coating is removed, it is required not to erode metals other than nickel. For example, in the production of a printed wiring board by the semi-additive method, after electroless nickel plating or nickel deposition is performed on an insulating substrate such as a glass cloth epoxy resin impregnated board or a polyimide film, , A copper circuit is formed on the nickel not covered with the resist by electrolytic copper plating, and then the resist is removed, and then the exposed nickel is etched. The nickel etching solution used in this case is required to etch the nickel without eroding the copper circuit.

Conventionally, an etching solution containing an acid such as nitric acid and hydrogen peroxide has been used as an etching solution for removing nickel without eroding copper. Additives for suppressing corrosion of copper are usually added to these nitric acid-hydrogen peroxide-based nickel etching solutions (see, for example, Patent Documents 1 to 8).

[Patent Document 1] Japanese Patent Publication (Tokukai) No. 62-11070

[Patent Document 2] Japanese Patent Publication (Kokai) No. 62-14034

[Patent Document 3] Japanese Patent Publication (Kokai) No. 62-14035

[Patent Document 4] Japanese Patent Publication No. 58-500765

[Patent Document 5] JP-A-6-57454

[Patent Document 6] JP-A-9-228075

[Patent Document 7] Japanese Patent Application Laid-Open No. 2001-140084

[Patent Document 8] Japanese Patent Application Laid-Open No. 2005-36256

However, suppression of copper erosion is not sufficient even with these etchants, and a nickel etchant whose copper erosion is further suppressed in the market is desired.

It is an object of the present invention to overcome the drawbacks of the prior art and to provide a nickel etching solution capable of suppressing erosion of metals other than nickel, particularly copper.

In order to achieve the above object, the etching solution of the present invention comprises a polymer having at least one repeating unit selected from the following chemical formulas I, II and III: nitric acid or sulfuric acid, hydrogen peroxide and water And the like.

(I)

≪

(III)

Wherein R ₁ to R ₅ are independently selected from the group consisting of hydrogen, amino, imino, cyano, azo, thiol, sulfo, hydroxyl, carbonyl, carboxyl, And the amine contained in the repeating unit may be in the form of a quaternary ammonium salt.

Further, the etching solution of the present invention is a nickel etching solution, but this " nickel " includes not only pure nickel but also nickel alloy. The same also applies to " copper " Here, the "alloy" means, for example, a metal containing at least 50% by weight of the main metal.

According to the etching solution of the present invention, since it contains a polymer having at least one repeating unit selected from the above-mentioned formulas (I), (II) and (III), it is possible to suppress metals other than nickel, particularly copper corrosion.

BEST MODE FOR CARRYING OUT THE INVENTION [

The etching solution of the present invention is characterized in that it comprises a polymer having at least one repeating unit selected from the above-mentioned formulas (I), (II) and (III) in a nickel etching solution containing nitric acid or sulfuric acid, hydrogen peroxide and water. In the etching solution of the present invention, since the polymer is a metal erosion inhibitor other than nickel, only nickel can be selectively etched from a to-be-treated material in which nickel and another metal coexist. Particularly, when the other metal is copper, the function of the polymer as an erosion inhibitor is more effectively exhibited.

The acid component of the etching solution of the present invention dissolves nickel oxidized with hydrogen peroxide, and nitric acid or sulfuric acid is used as nickel dissolving property. Further, the acid component also has an action of promoting the oxidation of nickel as a co-oxidant. Among these acid components, sulfuric acid has a smaller effect of dissolving copper than nitric acid, but also has a smaller effect of dissolving nickel. Therefore, from the viewpoint of the working time, it is preferable to use nitric acid as the acid component of the present invention.

The concentration of the acid component in the etching solution is adjusted in accordance with the etching rate and the allowable nickel dissolution amount of the etching solution, but is preferably 1.0 wt% to 38.5 wt%, more preferably 3.0 wt% to 27.0 wt%. When it is 1.0% by weight or more, the etching rate is increased, so that nickel can be rapidly etched. By setting the content to 38.5% by weight or less, erosion of metals other than nickel (particularly, copper) can be easily suppressed.

The concentration of hydrogen peroxide in the etching solution is adjusted in accordance with the etching rate and the ability to remove nickel, but is preferably 0.0175 wt% to 17.5 wt%, more preferably 0.035 wt% to 14.0 wt%, and most preferably 0.35 wt% to 7.0 wt% %. When it is 0.0175% by weight or more, nickel can be removed quickly because the etching rate is increased. On the other hand, by setting the content to 17.5% by weight or less, erosion of a metal other than nickel (particularly, copper) can be easily suppressed.

In the etching solution of the present invention, a polymer having at least one repeating unit selected from the above-mentioned formulas (I), (II) and (III) is mixed as an erosion inhibitor. The polymer may be a copolymer comprising at least one repeating unit selected from the above-mentioned formulas (I), (II) and (III) and other repeating units, and may be a copolymer comprising the repeating unit represented by the above formula (I) Or may be a copolymer comprising two or more repeating units selected from the above-mentioned formula (I), (II) and (III).

Examples of the polymer having a repeating unit represented by the above-mentioned formula (I) include condensation polymers using, for example, epichlorohydrin as a monomer. The type of condensation polymer is not particularly limited and may be suitably selected from commercially available surfactants It is possible. Among them, in order to selectively etch only nickel from a material to be treated in which nickel and copper coexist, a polymer having a repeating unit formed by epichlorohydrin and a nitrogen compound is preferable, and a repeating unit represented by the following formula (IV) Is preferred.

(IV)

Wherein R ₆ and R ₇ are independently selected from the group consisting of hydrogen, amino, imino, cyano, azo, thiol, sulfo, hydroxyl, carbonyl, carboxyl, And X ^- is a chloride ion, a bromide ion, an iodide ion, an acetic acid ion or a carbonate ion.

ER1 / ER2 (hereinafter referred to as " ER2 ") of an etching rate for nickel (hereinafter referred to as " ER1 ") and an etching rate for copper ) Can be increased. As a result, only the nickel can be reliably etched from the object to be treated in which nickel and copper coexist. Examples of such a polymer include dimethylamine / epichlorohydrin condensation polymer, dimethylamine / ammonia / epichlorohydrin condensation polymer, adipic acid / dimethylamine / epichlorohydrin / diethylenetriamine condensation polymer and the like. . Further, when ammonia is used as the monomer, R ₆ and R ₇ in the repeating unit represented by the above formula (IV) are all hydrogen. When dimethylamine is used as a monomer, R ₆ and R ₇ in the repeating unit represented by the above formula (IV) are all methyl groups.

Examples of the polymer having a repeating unit represented by the above formula (II) include condensation polymers using diallylamine as a monomer. The condensation polymers are not particularly limited and may be appropriately selected from commercially available surfactants Do. Specific examples thereof include a condensation polymer composed of a diallylamine hydrochloride and a diallylamine / acrylic acid / acrylamide condensation polymer. When diallylamine is used as a monomer, R ₁ in the repeating unit represented by the above formula (II) becomes hydrogen.

Examples of the polymer having a repeating unit represented by the above-mentioned formula (III) include condensation polymers using dicyandiamide as a monomer, and the type is not particularly limited and can be suitably selected from commercially available surfactants Do. Specific examples thereof include dicyandiamide / formaldehyde condensation polymers, dicyandiamide / diethylene triamine condensation polymers, and the like. Further, when dicyandiamide is used as a monomer, all of R ₂ to R ₅ in the repeating unit represented by the above formula (III) become hydrogen.

The concentration of the polymer in the etching solution of the present invention is preferably 0.0001 wt% to less than 3 wt%, more preferably 0.0005 wt% to 1.5 wt%, and still more preferably 0.001 wt% to 1.0 wt%. Within this range, erosion of metals other than nickel can be suppressed to such an extent that the etching of nickel is not inhibited.

The polymer preferably has a proportion of 10 to 100 mol% of the total repeating units occupied by one or more repeating units selected from the above-mentioned formula (I), (II) and (III). This is because the corrosion of the metal other than nickel can be suppressed more effectively. The molar fraction of the functional group or the specific element contained in the above formula (I), the above-mentioned formula (II) and the above formula (III) is determined by infrared (IR) analysis, elemental analysis, liquid chromatography, Can be calculated from the relationship between these values and the number average molecular weight. When the monomer composition is determined, the monomer ratio is the mole fraction. The denominator in the calculation of the molar fraction is the total number of moles of the minimum repeating units contained in the polymer.

The polymer preferably has a weight average molecular weight of 100 to 1,000,000, more preferably 100 to 500,000. Within this range, corrosion of the metal other than nickel can be inhibited more effectively without interfering with the solubility of the polymer.

Other components may be added to the etching solution of the present invention to such an extent as not to interfere with the effects of the present invention. For example, benzenesulfonic acids such as cresylsulfonic acid and phenols such as salicylic acid may be added as stabilizers for hydrogen peroxide. The concentration of these other components is, for example, about 0.01 to 5% by weight.

In addition, a chloride ion source may be added to accelerate the corrosion inhibiting effect of copper. Examples of the chloride ion source include hydrochloride salts such as hydrochloric acid, aniline hydrochloride, guanidine hydrochloride, and ethylamine hydrochloride; chlorides such as ammonium chloride, sodium chloride, zinc chloride, ferric chloride, cupric chloride, For example. The concentration of these chloride ion sources is usually about 1 to 60 ppm as a chloride ion.

The etching solution can be easily prepared by dissolving each component in water. The water is preferably water from which ionic substances or impurities have been removed, and for example, ion-exchanged water, pure water, ultrapure water and the like are preferable.

The etching solution may be formulated so that each component has a predetermined concentration at the time of use, or a concentrated solution may be prepared and diluted immediately before use. The method of using the etching solution is not particularly limited. Although the temperature of the etching solution is not particularly limited in use, it is preferably used at 20 to 50 占 폚 in order to etch nickel more quickly after suppressing metal erosion other than nickel.

<Examples>

Next, examples of the etching solution according to the present invention will be described together with comparative examples. The present invention is not limited to the following examples.

Polymers of the types (A to J) shown in Table 1 were used to prepare respective etching solutions having the compositions shown in Table 2, and the respective items were evaluated by the following measuring method. Each etching solution was prepared by first dissolving an acid and hydrogen peroxide in ion-exchange water, and then adding a polymer. As to the acid to be compounded, only sulfuric acid was used in Example 14, and the rest was nitric acid. When the weight average molecular weight shown in Table 1 was low (weight average molecular weight: 50 or more and 50,000 or less), the sample concentration was 5 wt% (solvent: Toluene). In the case of a high molecular weight (weight average molecular weight: 50,000 or more and 300,000 or less), the measurement was carried out under the same conditions as above using a membrane type molecular weight measuring apparatus manufactured by the same company.

&Lt; Etch rate for nickel (ER1) >

A 1 mm-thick rolled nickel plate (manufactured by Kojundo Chemical Co., Ltd.) was cut at 4 cm square and a test piece having a protective tape attached to one side thereof was prepared. Each of the etching solutions (liquid amount: 100 mL) shown in Table 2 was placed in a beaker, and the test pieces were immersed in each of the etching solutions (25 DEG C) using tweezers, and the test pieces were swung horizontally in the etching solution Sec) for one minute. Further, ER1 (mu m / minute) was calculated from the weight of each test piece before and after the treatment by the following formula.

(G / cm ³ ) ÷ immersion time (minutes) ER 1 (μm / min) = (weight before treatment - weight after treatment) / test piece area (m ² )

&Lt; Etching Rate for Copper (ER2) >

A copper foil having a thickness of 35 占 퐉 (GTMP manufactured by Furuka and circuit foil) was cut into 4 cm sides and a test piece having a protective tape on one side was prepared. Each of the etching solutions (liquid amount: 100 mL) shown in Table 2 was placed in a beaker, and the test pieces were immersed in each etching solution (25 DEG C) using tweezers, and the test pieces were swung horizontally in the etching solution 2 seconds) for 1 minute. Further, ER2 (占 퐉 / minute) was calculated from the weight of each test piece before and after the treatment by the following formula.

ER2 (㎛ / min) = (weight before treatment (g) - Weight after processing (g)) ÷ test piece surface area (m ²⁾ ÷ copper density (g / cm ³⁾ ÷ immersion time (in minutes)

The ratio (ER1 / ER2) of ER1 to ER2 was calculated for each of the etching solutions. The ER1 and ER2 of each etching solution and their ratios (ER1 / ER2) are shown in Table 2.

* Act on Regulation of Examination and Manufacture of Chemical Substances

As shown in Table 2, according to Examples 1 to 15 of the present invention, the etching rate ratios ER1 / ER2 were all higher than those of Comparative Examples 1 to 5. From these results, it has been found that according to the present invention, only the nickel can be selectively etched from an object to be treated in which nickel and other metals (copper, etc.) coexist.

Claims (6)

A nickel etchant comprising nitric acid or sulfuric acid, hydrogen peroxide and water, characterized in that it comprises a polymer having at least one repeating unit selected from the following general formula (I), (II) and (III) (I)

&Lt;

(III)

Wherein R ₁ to R ₅ are independently selected from the group consisting of hydrogen, amino, imino, cyano, azo, thiol, sulfo, hydroxyl, carbonyl, carboxyl, And the amine contained in the repeating unit may be in the form of a quaternary ammonium salt. The etching solution according to claim 1, which comprises a polymer having a repeating unit represented by the following formula (IV): (IV)

Wherein R ₆ and R ₇ are independently selected from the group consisting of hydrogen, amino, imino, cyano, azo, thiol, sulfo, hydroxyl, carbonyl, carboxyl, And X ^- is a chloride ion, a bromide ion, an iodide ion, an acetic acid ion or a carbonate ion. The etchant according to claim 1, wherein the polymer is contained in an amount of not less than 0.0001% by weight and less than 3% by weight. The etchant according to claim 1, wherein the ratio of the total repeating units of the polymer to the one or more repeating units selected from the group consisting of the formulas (I), (II) and (III) is 10 to 100 mol%. The etchant according to claim 1, wherein the polymer has a weight average molecular weight of 100 to 1,000,000. The etchant according to claim 1, wherein the concentration of the nitric acid or sulfuric acid is 1.0 wt% to 38.5 wt%, and the concentration of the hydrogen peroxide is 0.0175 wt% to 17.5 wt%.