JP2001140084A - Etching solution for nickel or nickel alloy - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce an etching solution for nickel or a nickel alloy in which the etching rate of the nickel or a nickel alloy is high, also, the erosion of the other metals such as copper and a copper alloy in particular is extremely small, and moreover, side etching is hardly occurred. SOLUTION: In an etching solution in which, from the material in which nickel or a nickel alloy and the other metals are coexistent, the nickel or nickel alloy is selectively etched, this etching solution for nickel or a nickel alloy is composed of an aqueous solution containing (A) nitric acid of 5 to 5 weight %, (B) sulfuric acid of 0.5 to 40 weight %, (C) the main oxidizer selected from peroxide, nitrate and an aromatic nitro compound of 0.1 to 20 weight % and (D) chlorine ions of 0.0001 to 0.5 weight %.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an etching solution capable of selectively etching nickel or a nickel alloy from a composite material in which nickel or a nickel alloy and other metals coexist. The etching solution of the present invention is particularly useful in the production of electronic parts such as semiconductor products and printed wiring boards.

[0002]

2. Description of the Related Art In the manufacture of electrodes and wiring of printed wiring boards including flexible substrates for TAB and BGA package, electrodes of semiconductor products, etc., there is a step of forming a nickel film by electroplating or electroless plating.
At this time, the nickel film formed on the unnecessary portion is peeled off by the etchant. Since the electrodes and wires are made of a plurality of metals, when peeling off the nickel film,
It is required not to erode metals other than nickel. For example, in the manufacture of printed wiring boards by the semi-additive method, after performing electroless nickel plating or nickel vapor deposition on an insulating substrate such as a glass cloth epoxy resin impregnated plate or a polyimide film, a reverse pattern of a circuit is formed with a plating resist. Next, a copper circuit is formed on the nickel by electrolytic copper plating, and then the plating resist is stripped, and then the exposed nickel is stripped. The nickel etchant used in this case is required not to attack the copper circuit.

As an etchant for stripping nickel without eroding copper, JP-A-6-57454 discloses an acid solution containing nitric acid and hydrogen peroxide, an organic acid containing a carboxyl group as an additive, and -NH-. Alternatively, an etchant comprising an aqueous solution containing a heterocyclic compound containing a nitrogen atom in the form of = N- is disclosed. Japanese Patent Application Laid-Open No. 9-2
No. 28075 discloses an acid containing no halogen ion,
An etchant comprising an aqueous solution containing an oxidizing agent such as hydrogen peroxide, an aromatic nitro compound, a metal dissolution inhibitor such as an organic dye or an azole is disclosed.

[0004]

However, even with these etchants, the suppression of copper erosion is not sufficient, and there is a demand in the market for a nickel etchant which further suppresses copper erosion. Accordingly, the present invention overcomes the drawbacks of the prior art and provides an etching solution for nickel or nickel alloy in which the etching rate of nickel or nickel alloy is high and the erosion of other metals, particularly copper or copper alloy, is extremely small. The purpose is to: It is a further object of the present invention to provide a nickel or nickel alloy etchant that hardly causes side etching (dissolution of nickel under copper).

[0005]

Means for Solving the Problems As a result of intensive studies, the present inventors have overcome the above-mentioned disadvantages of the prior art by the following constitution. The present invention has been made to obtain an etching solution for nickel or a nickel alloy in which the etching rate of nickel or a nickel alloy is high and the erosion of other metals, particularly copper or a copper alloy, is extremely small. Nitric acid 5-55% (% by weight, the same applies hereinafter),
(B) 0.5 to 40% of sulfuric acid, (C) 0.1 to 0.1 of a main oxidizing agent selected from peroxides, nitrates and aromatic nitro compounds.
20% and (D) chloride ion 0.0001 to 0.5
% Of an aqueous solution containing nickel or nickel alloy. The present invention also relates to an etching solution for nickel or a nickel alloy, wherein the aqueous solution further contains 0.01 to 6% of a pyridine derivative.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail. Nitric acid in the etching solution of the present invention is a component that dissolves nickel oxidized by the main oxidizing agent.
It also has the effect of promoting the oxidation of nickel as an auxiliary oxidant. The concentration of nitric acid is 5 to 55%, preferably 10 to
It is 40%, more preferably 20 to 30%. If the concentration is less than 5%, the etching rate of nickel becomes slow, and if it exceeds 55%, nickel may be passivated and cannot be etched.

In the present invention, sulfuric acid is used together with nitric acid to dissolve oxidized nickel. Since nitric acid and sulfuric acid are used together in this way, the etching rate of nickel is higher than in the case where sulfuric acid is not used together. The concentration of sulfuric acid is 0.5-40%, preferably 0.1-10%,
More preferably, it is 1 to 5%. The concentration is 0.5%
If the amount is less than 40%, the effect of increasing the etching rate of nickel is insufficient. If the amount exceeds 40%, nickel may be passivated and may not be etched.

[0008] The main oxidizing agent used in the etching agent of the present invention is a component that oxidizes nickel, and at least one of peroxide, nitrate and aromatic nitro compound is used. Examples of the peroxide include hydrogen peroxide, sodium peroxide, barium peroxide, benzoyl peroxide and the like. Examples of the nitrate include ammonium nitrate, sodium nitrate, potassium nitrate, iron nitrate and nickel nitrate. Examples of the aromatic nitro compound include nitrobenzenesulfonic acid, nitrobenzoic acid, nitroaniline, nitrophenol, and salts thereof. Examples of the salt include sodium nitrobenzenesulfonate and sodium nitrobenzoate.

[0009] The concentration of the main oxidizing agent is 0.1-20%, preferably 0.1-5%, more preferably 0.5-2%. If the concentration is less than 0.1%, the oxidizing power is insufficient and the etching rate of nickel becomes slow, and if it exceeds 20%, erosion of copper and the like becomes large.

[0010] Chlorine ions used in the etching solution of the present invention are components that suppress the dissolution of copper and the like. The chloride ion is, for example, hydrochloric acid, aniline hydrochloride, guanidine hydrochloride, hydrochloride such as ethylamine hydrochloride, ammonium chloride,
Sodium chloride, zinc chloride, ferric chloride, cupric chloride,
It is preferably added as a chloride such as nickel chloride. The concentration of the chloride ion is 0.0001 to 0.5%,
Preferably it is 0.0001-0.001%, More preferably, it is 0.0001-0.005%. When the concentration is less than 0.0001%, erosion of copper and the like becomes large,
If it exceeds 0.5%, the etching rate of nickel decreases.

When the etching agent of the present invention is used for pattern etching, it is preferable to add a pyridine compound to prevent side etching. For example, in the manufacture of a printed wiring board by a semi-additive method, when performing electroless nickel plating or the like as a base plating and etching nickel after forming a circuit by electrolytic copper plating, using an etching solution of the present invention to which a pyridine compound is added is used. In addition, side etching (dissolution of nickel under copper) hardly occurs.

The pyridine compound is a compound in which pyridine and its hydrogen atom are substituted by substituents such as a halogen atom, an amino group, a hydroxyl group, an alkyl group, an arylalkyl group, a vinyl group and a benzoyl group. Include pyridine, 2-chloropyridine, 2-bromopyridine, 3-fluoropyridine, 2,6-dichloropyridine, 2-aminopyridine, 2,3-diaminopyridine, 3-hydroxypyridine, 2,4, -dimethyl Pyridine, 2,4,6-trimethylpyridine, 2-hydroxymethylpyridine, 2- (2-hydroxydiethyl) pyridine, 2-vinylpyridine, 2-vinylpyridine,
-(3-phenylpropyl) pyridine, 4-benzoylpyridine and the like.

The concentration of the pyridine compound is 0.01 to 6
%, Preferably 0.1 to 3%, more preferably 0.1%
~ 1%. If the concentration is less than 0.01%, the effect of suppressing the side etching is small, while if it exceeds 6%, the effect corresponding to the increase in the added amount is not increased.

Components other than the above-mentioned components may be added to the nickel etching solution of the present invention, if necessary. For example, halide ions such as bromide ions and iodine ions may be added to promote the dissolution of nickel, and a nonionic surfactant or a water-soluble solvent may be added to improve wettability to the material to be treated. You may.

[0015] The etching solution of the present invention comprises the above component as water,
Preferably, it can be easily prepared by mixing and stirring with ion-exchanged water.

The method of using the etching solution of the present invention is not particularly limited, and examples thereof include a method of immersing a material to be processed in the etching solution and a method of spraying the etching solution. The contact time between the etching solution and the material to be processed, the liquid temperature, and the like are appropriately selected depending on the type of the material to be processed, the thickness of nickel to be etched, and the like.

[0017]

EXAMPLES Examples 1 to 7 and Comparative Examples 1 to 4 The components shown in Tables 1 and 2 were mixed to prepare an etching solution. The nickel etching rate and the copper erosion rate of the obtained liquid were examined as described below, and the copper surface was visually observed for discoloration. The results are shown in Tables 1 and 2.

(Measurement of nickel etching rate) 40 m
mx 40 mm x 0.3 mm nickel plate (specific gravity 8.84
5) was left standing in an etching solution at 25 ° C. for 3 minutes and then taken out, and the etching rate was calculated from the change in the weight of the nickel plate by the following equation.

[0019]

(Equation 1)

(Measurement of copper erosion rate) 40 mm × 40 mm
A copper plate having a size of 0.3 mm (specific gravity: 8.92) was allowed to stand in an etching solution at 25 ° C. for 3 minutes, and then taken out. From the weight change of the copper plate, the erosion rate was calculated by the following equation.

[0021]

(Equation 2)

[0022]

[Table 1]

[0023]

[Table 2]

As shown in Tables 1 and 2, the etching solution of the present invention had a high nickel etching rate, had very little copper erosion, and did not change the appearance of copper. On the other hand, when the nitric acid concentration is lower than the etching solution of the present invention (Comparative Example 1), the nickel etching rate is low, and when the nitric acid concentration is high (Comparative Example 2), nickel is passivated and almost no peeling is possible. Did not. When there is no further chloride ion (Comparative Examples 3 and 4)
In this case, the etching rate of nickel was high, but the erosion of copper was large.

Examples 8 to 11 The components shown in Table 3 were mixed to prepare an etching solution. The nickel etching rate, the copper erosion rate, and the presence or absence of discoloration on the copper surface of the obtained liquid were examined in the same manner as in Example 1. Table 3 shows the results. Also, after forming a 0.5 μm thick plating film by electroless nickel plating on a polyimide substrate,
A reverse pattern of the circuit was formed using a plating resist, and then copper electroplating was performed to form a copper circuit. Next, the plating resist was peeled off to prepare a test substrate. The obtained test substrate was immersed in an etching solution at 25 ° C. for 5 minutes, taken out, cut, and observed under a microscope with a magnification of 400 × to examine nickel side etching under the copper pattern. Table 3 shows the results.

[0026]

[Table 3]

As shown in Table 3, the etching solution of the present invention had a high nickel etching rate and very little copper erosion, and did not change the appearance of copper. Further, dissolution of nickel (side etching) under the copper pattern was not observed.

[0028]

According to the present invention, it is possible to provide an etching solution for nickel or a nickel alloy in which the etching rate of nickel or a nickel alloy is high and erosion of other metals, particularly copper or a copper alloy, is extremely small. . Further, according to the present invention, it is possible to provide an etching solution of nickel or a nickel alloy in which side etching hardly occurs.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4K057 WA13 WB03 WB15 WE02 WE03 WE08 WE09 WE11 WE15 WE16 WE25 WE30 WG03 WN01 5E339 BC01 BC02 BE13 BE17 GG02 5F043 AA26 BB15 FF10 GG02 GG04

Claims (2)

[Claims] An etchant for selectively etching nickel or a nickel alloy from a material in which nickel or a nickel alloy and another metal are mixed,
(A) 5-55% by weight of nitric acid, (B) 0.5-40% by weight of sulfuric acid, (C) 0.1-20% by weight of a main oxidizing agent selected from peroxides, nitrates and aromatic nitro compounds; (D) An etching solution for nickel or a nickel alloy comprising an aqueous solution containing 0.0001 to 0.5% by weight of chloride ions. 2. The etching solution according to claim 1, comprising 0.01 to 6% by weight of a pyridine derivative.