TWI745603B - Copper etching solution - Google Patents

Abstract

The subject of the present invention is to provide a copper etching solution that can reliably suppress Galvanic corrosion, is easy to control the etching bath, and has an excellent etching rate. In order to solve the above-mentioned problems, a copper etching solution is provided, which is an alkaline copper etching solution, comprising 1 to 70 g/L of copper, 10 to 500 g/L of ammonia converted to 25% ammonia, and 5 to 500 g /L of ammonium salt, the aforementioned ammonium salt is selected from ammonium salt of inorganic acid, ammonium salt of sulfonic acid, ammonium salt of saturated fatty acid, ammonium salt of aromatic carboxylic acid, ammonium salt of hydroxy acid, One or two or more ammonium salts in the group of ammonium salts of dicarboxylic acids.

Description

Copper etching solution

The present invention relates to copper etching solutions.

In the past, as a method of forming a circuit pattern, it is known to provide an etching resist on a substrate with a copper foil of approximately 20 microns on the entire surface, and to etch and remove the exposed copper foil. )Law. Furthermore, as a method for forming finer circuit patterns, it is known to form a seed layer by electroless copper plating on the surface of a resin substrate, and to provide a plating resist on the seed layer and use copper electroplating to form a seed layer. The semi-additive method (SAP = Semi additive Process) in which the circuit is formed and then the seed layer remaining on the substrate between the circuits is etched and removed.

In the semi-additive method, as the copper etching solution used for the electroless copper etching removal of the seed layer, there are known, for example, sulfuric acid/hydrogen peroxide (Patent Documents 1 to 3), hydrochloric acid/divalent copper Type (Patent Document 4), hydrochloric acid/ferrous type (Patent Document 5) copper etching solution.

On the other hand, it is known that in order to reduce or avoid contact resistance and improve solder wettability, gold, silver, palladium, etc., can be made on the surface of copper constituting the circuit, which is a noble metal (with low ionization tendency). Metal) electroplating technology.

However, when the copper etching solution disclosed in the above-mentioned Patent Documents 1 to 5 is used to etch copper that is conductive to copper, which is a noble metal, it is conductive to copper that is a noble metal to copper compared to non-conductive to copper. Copper, a noble metal, promotes copper etching (Galvanic/Galvanic corrosion). As a result, there is a problem that the circuit becomes thinner, the resistance of the circuit becomes larger, or the circuit is broken, the circuit is further dissolved and disappeared, and the plating of the noble metal provided on the surface of the circuit may be peeled (disappeared).

As an etching solution that uses copper, which is a noble metal with respect to copper, in order to solve the above problems, known are those containing hydrogen peroxide, inorganic acid and chloride ions, and cyclohexylamine or piperidine. Etching solution (Patent Document 6). The copper etching solution has a low effect of inhibiting Gavanni corrosion when the chloride ion concentration is 1 ppm, and the etching rate decreases when the chloride ion concentration exceeds 20 ppm. Therefore, the chloride ion concentration is preferably 1-20 ppm. When the copper that is connected to gold and the copper that is not connected to gold (single copper) are etched by this copper etching solution, the diameter of the copper that is connected to the etched gold exceeds 90% of the diameter of the single copper. It can be seen that this copper etching solution has excellent performance in inhibiting Galvanic corrosion. [Prior Art Document] [Patent Document]

[Patent Document 1] Japanese Patent No. 4430990 [Patent Document 2] Japanese Patent No. 4443632 [Patent Document 3] Japanese Patent Laid-Open No. 2009-149971 [Patent Document 4] Japanese Patent Laid-Open No. 2006 -111953 Publication [Patent Document 5] Japanese Patent No. 3962239 [Patent Document 6] Japanese Patent Laid-Open No. 2013-245401

[The problem to be solved by the invention]

However, in the copper etching solution disclosed in Patent Document 6, when the diameter of copper before etching is 0.45 mm, the difference in diameter between copper and single copper that is connected to gold after etching is at most 0.045 mm (45 mm). Micrometers). It can be seen from this that it is expected that this copper etching solution can further suppress Galvanic corrosion. Moreover, since the preferred range of the chlorine concentration of the copper etching solution is as narrow as 1-20 ppm, it is necessary to precisely control the etching bath, but it is difficult to control the etching bath. Furthermore, since the etching speed of this copper etching solution is slow, it is expected that the etching speed can be higher.

The subject of the present invention is to provide a copper etching solution that can reliably suppress Galvanic corrosion, is easy to control the etching bath, and has an excellent etching rate. [Means used to solve the problem]

The copper etching solution according to the present invention is an alkaline copper etching solution, which includes 1 to 70 g/L of copper, 10 to 500 g/L of ammonia converted to 25% ammonia, and 5 to 500 g/L of ammonium Salt, the aforementioned ammonium salt is selected from the group consisting of ammonium salts of inorganic acids such as ammonium sulfate, ammonium bicarbonate and ammonium nitrate, ammonium salts of sulfonic acids which are ammonium methanesulfonate, ammonium salts of saturated fatty acids which are ammonium acetate, and benzoic acid An ammonium salt of an aromatic carboxylic acid of ammonium, an ammonium salt of a hydroxy acid of ammonium lactate, and an ammonium salt of a group of ammonium salts of dicarboxylic acid of ammonium oxalate.

The pH of the copper etching solution according to the present invention is 7.8-11.

The copper etching solution according to the present invention contains ammonium sulfate as the aforementioned ammonium salt, and the content of the aforementioned ammonium sulfate is 5 to 300 g/L.

The copper etching solution according to the present invention contains ammonium sulfate and ammonium bicarbonate as the aforementioned ammonium salt, and the content of the aforementioned ammonium sulfate is 5 to 80 g/L, and the content of the aforementioned ammonium bicarbonate is 0.5 to 200 g/L.

The copper etching solution according to the present invention contains ammonium sulfate and ammonium acetate as the aforementioned ammonium salt, and the content of the aforementioned ammonium sulfate is 5 to 80 g/L, and the content of the aforementioned ammonium acetate is 5 to 100 g/L. [Effects of the invention]

According to the copper etching solution of the present invention, it is an alkaline copper etching solution containing 10 to 500 g/L of the above-mentioned ammonium salt, thereby being able to suppress galvanic corrosion. Furthermore, the copper etching solution contains copper, ammonia and the ammonium salt, and since the concentration of each component is not lower than the ppm level and the concentration range is wide, it is easy to control the etching bath.

Hereinafter, an embodiment of the copper etching solution according to the present invention will be described. 1. Copper etching solution

The copper etching solution of this embodiment, on the premise that it is an alkaline copper etching solution, is characterized in that it contains 1 to 70g/L (grams/liter) of copper, and is converted to 25% ammonia (ammonia) water. 10～500g/L of ammonia water and 5～500g/L of ammonium salt. Since the copper etching solution of this embodiment is alkaline, it can suppress Galvanic corrosion. copper:

The copper system constitutes a supply source of copper ions for the ^{ammine complex ([Cu II} (NH ₃ ) ₄ ] ²⁺ ) that functions as an oxidizing agent for the copper etching solution. Examples of copper used in the copper etching solution include metallic copper, copper oxide, copper salt, and the like. From the standpoint of solubility in water _{, water-soluble copper salts such as copper sulfate pentahydrate (CuSO 4} ‧5H ₂ O) and copper carbonate are preferred, and from the standpoint of ease of preparation, copper sulfate pentahydrate is particularly Fit.

The content of copper in the copper etching solution is in the range of 1 to 70 g/L. When the copper content is within this range, good etching bath stability can be obtained while ensuring a good etching rate. If the copper content is less than 1 g/liter, since copper is not sufficient with respect to ammonia, the amount of copper ammonia complexes formed is reduced, and the etching rate is reduced, so it is not an appropriate choice. When the etching rate decreases, productivity decreases. On the other hand, if the copper content exceeds 70 g/liter, since copper is excessive with respect to ammonia, precipitation of copper (copper hydroxide) occurs, which is not an appropriate choice. ammonia:

Ammonia constitutes the supply source of ammonia of the copper ammonia complex, and also has a function as a pH adjuster. The content of ammonia in the copper etching solution is in the range of 10 to 500 g/liter converted from 25% ammonia. Within this range, it is possible to maintain a good etching rate while maintaining the pH within a range that can suppress Galvanic corrosion. If the content of ammonia water is less than 10 g/liter, the ammonia is not sufficient with respect to copper, and copper precipitation occurs, so it is not an appropriate choice. On the other hand, if the content of ammonia water exceeds 500 g/liter, the pH becomes too high or it becomes difficult to maintain the pH in the range of 7.8 to 10 during continuous use, so it is not an appropriate choice. Ammonium salt:

The ammonium salt provides the component of the counter ion of the copper-ammonia complex, and has the function of inhibiting the corrosion of galvanic. As the ammonium salt, ammonium salts selected from inorganic acids such as ammonium sulfate, ammonium bicarbonate, and ammonium nitrate, ammonium salts of sulfonic acids such as ammonium methanesulfonate, and ammonium salts of saturated fatty acids such as ammonium acetate can be used. Ammonium salts of aromatic carboxylic acids such as ammonium benzoate, ammonium salts of hydroxy acids such as ammonium lactate, and ammonium salts of dicarboxylic acids such as ammonium oxalate. .

The content of the ammonium salt in the copper etching solution is 5 to 500 g/L. This is the total amount of all ammonium salts. When the content of the ammonium salt is within this range, the corrosion of galvanic can be suppressed. If the content of the ammonium salt is less than 5 g/L, the corrosion of galvanic cannot be suppressed, so it is not an appropriate choice. On the other hand, if the content of the ammonium salt exceeds 500 g/L, since the etching rate becomes too fast, it is not an appropriate choice. When the etching rate becomes too fast, the etching time becomes shorter and it becomes difficult to control the etching time. In addition, Galvanic corrosion cannot be suppressed, and the cost increases, so it is not an appropriate choice. The content of ammonium salt is preferably 20-300 g/liter, preferably 50-200 g/liter.

In the case of a copper etching solution containing ammonium sulfate as an ammonium salt, the content of ammonium sulfate is preferably 5 to 300 g/liter. If the content of ammonium sulfate is less than 5 g/L, the etching rate will decrease, so it is not an appropriate choice. On the other hand, if the content of ammonium sulfate exceeds 300 g/liter, the etching rate becomes too fast, the stability of the etching bath becomes poor, and precipitation becomes easy to occur, so it is not an appropriate choice.

In the case of a copper etching solution containing ammonium sulfate and ammonium bicarbonate as the ammonium salt, the content of ammonium sulfate is preferably 5 to 80 g/liter, and the content of ammonium bicarbonate is preferably 0.5 to 200 g/liter. Ammonium bicarbonate also functions as a pH buffer. If the content of ammonium sulfate is less than 5 g/L, the etching rate will decrease, so it is not an appropriate choice. On the other hand, if the content of ammonium sulfate exceeds 80 g/liter, the etching rate becomes too fast, the stability of the etching bath deteriorates, and precipitation becomes easy to occur, so it is not an appropriate choice. Furthermore, if the content of ammonium bicarbonate is less than 0.5 g/L, the etching rate will be reduced, so it is not an appropriate choice. On the other hand, if the content of ammonium bicarbonate exceeds 200 g/L, the etching rate becomes too fast, the stability of the etching bath deteriorates and precipitation becomes easy to occur, and therefore it is not an appropriate choice.

Furthermore, in the case of a copper etching solution containing ammonium sulfate and ammonium acetate as the ammonium salt, the content of ammonium sulfate is preferably 5 to 80 g/liter, and the content of ammonium acetate is preferably 5 to 100 g/liter. Ammonium acetate also functions as a pH buffer. If the content of ammonium sulfate is less than 5 g/L, the etching rate will decrease, so it is not an appropriate choice. On the other hand, if the content of ammonium sulfate exceeds 80 g/L, the etching rate becomes too fast, and it may not be possible to suppress Galvanic corrosion, so it is not an appropriate choice. Furthermore, if the content of ammonium acetate is less than 5 g/L, the etching rate will decrease, so it is not an appropriate choice. On the other hand, if the content of ammonium acetate exceeds 100 g/L, the etching rate becomes too fast, and sometimes it may not be possible to suppress galvanic corrosion, so it is not an appropriate choice.

In addition to the above-mentioned components, the copper etching solution of the present embodiment may contain an inhibitor for suppressing copper etching, a surfactant that reduces surface tension, and the like.

The copper etching solution of this embodiment contains copper, ammonia water, and the above-mentioned ammonium salt, and each concentration is not lower than the ppm level and the concentration range is wide, so the etching bath can be easily controlled. pH:

The pH of the copper etching solution is preferably 7.8-11. The pH of the copper etching solution can be adjusted by, for example, the amount of ammonia water added. When the pH of the copper etching solution is within the above-mentioned range, it is possible to reliably suppress galvanic corrosion, and at the same time, an etching bath with excellent stability can be obtained. If the pH is less than 7.8, precipitation of copper will occur, so it is not an appropriate choice. On the other hand, it is difficult to make the pH exceed 11 only by adding ammonia water. Furthermore, if the pH exceeds 10, it becomes difficult to maintain the pH within a predetermined range, and therefore it is not an appropriate choice. Etching bath temperature:

The temperature of the etching bath of the copper etching solution is preferably adjusted to 10-60°C. If the etching bath temperature is less than 10°C, the etching rate becomes slow, so it is not an appropriate choice. On the other hand, if the etching bath temperature exceeds 60°C, the etching rate becomes too fast, and the stability of the etching bath decreases, so it is not an appropriate choice. Etching speed:

The copper etching solution contains 1~70g/L of copper, 10~500g/L of ammonia converted into 25% ammonia water, and 5~500g/L of the above ammonium salt, the pH is 7.8~11, and the etching bath temperature At 10-60°C, copper can be etched at a rate of 0.2-40 microns/min (electroless copper plating).

Therefore, according to the copper etching solution of this embodiment, it is possible to obtain a higher etching rate than a copper etching solution composed of an acidic aqueous solution. The etching rate can be easily controlled by adjusting the concentration of the components of the copper etching solution. 2. Etching method using copper etching solution

Next, the etching method using the copper etching solution of this embodiment is demonstrated. For example, in the case of manufacturing a printed circuit board by a semi-additive method, the copper etching solution of this embodiment is suitably used when the seed layer remaining on the substrate between the circuits is etched and removed.

The etching reaction of copper by the copper etching solution is represented by the following formula (1). The formula (1) means that the copper ammonia complex (divalent) contained in the copper etching solution functions as an oxidizing agent, which will dissolve the seed layer of metallic copper and generate the copper ammonia complex (monovalent). Cu ⁰ + [Cu ^II (NH ₃ ) ₄ ] ²⁺ →2[Cu ^I (NH ₃ ) ₂ ] ⁺ ‧‧‧（1）

This copper ammonia complex (monovalent) uses ammonia and dissolved oxygen in the copper etching solution to regenerate a copper ammonia complex (divalent). This regeneration reaction is represented by the following formula (2). The regenerated copper ammonia complex (divalent) can be reused in the etching reaction of formula (1). _{^{2 [Cu I (NH 3)}} 2] + + 4NH 4+ + 1 / 2O 2 + 2OH - → 2 [Cu II (NH 3) 4] 2+ + 3H 2 O‧‧‧ (2)

FIG. 1 illustrates the seed layer removed by the copper etching solution of this embodiment. The seed layer 2 is formed on the surface of the resin substrate 1 by electroless copper plating, and the circuits 3a, 3b and the electrodes 4 are formed on the seed layer 2 by copper electroplating. Then, the part 2a between the circuits 3a and 3b and the part 2b between the circuit 3a and the electrode 4 in the seed layer 2 are removed by the copper etching solution of this embodiment. Hereinafter, 2a and 2b are referred to as portions of the seed layer 2 that need to be etched and removed.

On the surfaces of the circuits 3a, 3b, in order to reduce or avoid contact resistance and improve solder wettability, a gold film 5 is provided by electroplating or electroless plating. Then, between the circuits 3a, 3b and the gold film 5, in order to prevent the diffusion of copper from the circuits 3a, 3b to the gold film 5, a nickel film 6 is provided by electroplating or electroless plating. That is, a nickel film 6 is provided on the surfaces of the circuits 3a, 3b, and a gold film 5 is provided thereon.

On the surface of the electrode 4, similar to the circuits 3a and 3b, a nickel film 7 and a gold film 8 are provided by electroplating or electroless plating.

The circuit 3a is not only electrically connected to the gold film 5 provided on the surface of the circuit 3a itself, but also electrically connected to the gold film provided on the surface of other objects other than the circuit 3a. In this embodiment, the circuit 3a is electrically connected to the gold film 8 provided on the surface of the electrode 4 via the inner layer circuit 9 embedded in the resin substrate 1. The inner layer circuit 9 is made of a metal having excellent conductivity, and in this embodiment is made of copper. Hereinafter, the circuit 3a is referred to as "a circuit that conducts to a noble metal with respect to copper". The noble metals mentioned here refer to "gold".

On the other hand, the circuit 3b is only electrically connected to the gold film 5 provided on the surface of the circuit 3b itself, and is not electrically connected to the gold films 5 and 8 provided on the surface of objects other than the circuit 3b. However, in the state before the etching shown in FIG. 1, the circuit 3b is electrically connected to the gold film 5 provided on the surface of the circuit 3a via the seed layer 2, and after the seed layer 2 is removed by etching, the circuit 3b becomes no longer electrically connected to circuit 3a. Therefore, the circuit 3b can not be electrically connected to the gold films 5 and 8 other than the gold film 5 provided on the surface of the circuit 3b itself. Hereinafter, the circuit 3b is referred to as a "no continuity to a circuit that is a noble metal with respect to copper".

When the resin substrate 1 shown in FIG. 1 is immersed in a copper etching solution, the ideal result is to etch away only the portions 2a and 2b of the seed layer 2 that need to be etched away. However, not only the parts 2a, 2b, but also the circuits 3a, 3b and the part of the seed layer 2 directly below the electrode 4 or the side surfaces of the circuits 3a, 3b and the electrode 4 itself will also be dissolved (undercut). Hereinafter, the undercut amount of the circuits 3a and 3b is referred to as "reduction amount L". Furthermore, it is preferable to end the etching at a point in time when the portions 2a, 2b of the seed layer 2 that need to be etched and removed disappear and the surface of the resin substrate 1 underneath is exposed. Hereinafter, the time point at which the surface of the resin substrate 1 underneath is exposed due to etching is referred to as “just etch”. Moreover, the thickness of the seed layer 2 is not completely uniform over the entire surface. Therefore, in order to completely remove the portions 2a and 2b of the seed layer 2 that need to be etched away, it is necessary to perform etching beyond the "just etching".

For example, the reduction amount L can be calculated by the following formula (3). Reduction L = {(diameter of circuit 3a, 3b before etching) —(diameter of circuit 3a, 3b after etching)}/2‧‧‧(3)

Alternatively, with the copper etching solution of this embodiment, the nickel film 6 and the gold film 5 on the top surface of the circuits 3a, 3b are not etched, so the end surface of the nickel film 6 or the gold film 5 may reach the circuits 3a, 3b. The distance from the side is taken as the reduction amount L.

The resin substrate 1 shown in FIG. 1 is provided with a circuit 3a which conducts to a noble metal to copper and a circuit 3b which does not conduct to a noble metal to copper. In the case of using the copper etching solution of the prior art disclosed in Patent Documents 1 to 5 to remove the portions 2a and 2b of the seed layer 2 that need to be etched away, as shown in FIG. 2, compared to the circuit 3b, the circuit 3a is reduced The amount L becomes significantly larger. In this case, the circuit 3a is thinned (undercut), which causes the resistance increase or disconnection, and the circuit 3a further disappears. As a result, the nickel film 6 and the gold film 5 on the surface of the circuit 3a may be peeled (disappeared). doubt.

In contrast, when the seed layer 2 is etched using the copper etching solution of the present embodiment, as shown in FIG. 3, the reduction amount L of the circuit 3a can be made the same as that of the circuit 3b. Furthermore, even in the case of performing etching beyond "just etching", it is possible to suppress the difference in the reduction amount L between the circuit 3a and the circuit 3b from increasing.

Therefore, according to the copper etching solution of the present embodiment, it is possible to suppress galvanic corrosion, and conduct between copper (circuit 3a), which is a noble metal with respect to copper, and copper (circuit 3b), which is a noble metal with respect to copper. The etching amount can be the same degree. Thereby, compared with the copper which is not conductive to the noble metal to copper, the copper which is conductive to the noble metal to copper is etched more excessively, and it is possible to prevent an increase in resistance or the occurrence of disconnection. Furthermore, it is possible to prevent the nickel film 6 and the gold film 5 from being peeled off by preventing the conduction to copper (circuit 3a), which is a noble metal with respect to copper, from disappearing.

In this embodiment, the circuit 3a is connected to copper, which is a noble metal to copper, and the noble metal is gold. However, as a noble metal to copper, other materials other than gold can also be cited. , Silver, palladium (palladium), iridium (iridium), platinum or their alloys.

In this embodiment, the circuit 3b is non-conductive to copper, which is a noble metal with respect to copper. As the circuit 3b, a circuit in which a gold film 5 is provided on the surface of the circuit 3b itself via a nickel film 6 is also mentioned. Examples include circuits whose surface (upper surface) is exposed without any thin film, and there is no circuit connected to the gold film provided on the surface of an object other than itself (no contact or conduction to copper, which is a noble metal with respect to copper). ). This kind of circuit does not contact and does not conduct to a circuit that is a noble metal to copper. According to the copper etching solution of this embodiment, it can also reduce the amount of circuit reduction L and conduction to the circuit 3a that is a noble metal to copper. The amount L is the same degree. Furthermore, in the case where the upper surface is not provided with any thin film to expose the surface of the circuit, because not only the side of the circuit but also the upper surface of the circuit are also etched, the reduction of this circuit is based on the above formula (3) It’s better to calculate.

Hereinafter, the present invention will be specifically explained based on examples and the like. [Example] 1. Etching test using circuit board

1-1. Preparation of copper etching solution Here, the circuit board is used for etching test. First, the copper etching solutions of Examples 1 to 3 shown in Table 1 were prepared. The "-" in Table 1 means that this ingredient is not added. The values shown in parentheses () of copper sulfate pentahydrate in Table 1 are values converted from copper. In Comparative Example 1, a commercially available copper etching solution (sulfuric acid-hydrogen peroxide) (pH 1 or less) was used. In Comparative Example 2, a commercially available copper etching solution (acid etching bath containing chlorine) (pH 1 or less) was used. In Comparative Example 3, an acidic copper etching solution (pH 1 or less) containing iron sulfate was prepared, and the etching bath temperature was 35°C.

[Table 1]

1-2. Etching test Then, as described below, use the circuit board to perform an etching test. As the test piece, a circuit board provided with a circuit that conducts to a noble metal to copper and a circuit that does not conduct to a noble metal to copper is provided on a resin substrate. As shown in Figure 1, this test piece is formed by forming a seed layer 2 on the surface of the resin substrate 1 by electroless copper plating, and forming circuits 3a, 3b and electrodes 4 on the seed layer 2 by electroplating copper. Circuit board W. The diameter of any one of the circuits 3a and 3b is 40 micrometers, and a nickel film 6 and a gold film 5 are provided on the surface thereof. The electrode 4 has a diameter of 100 micrometers and has a diameter larger than that of the circuits 3a and 3b, and a nickel film 7 and a gold film 8 are provided on the surface thereof. Furthermore, the circuit 3a is electrically connected to the gold film 8 of the electrode 4 via the inner layer circuit 9 embedded in the resin substrate 1. On the other hand, the circuit 3b is electrically connected to the gold film 5 provided on the surface of the circuit 3b itself, but is not electrically connected to the gold films 5, 8 other than itself. In this test piece, 10 circuits 3a, 50 circuits 3b, and 10 electrodes 4 are mixedly arranged on the resin substrate 1, and one circuit 3a is connected to one electrode 4.

The above-mentioned test piece was immersed in the copper etching solution of this embodiment. The part 2a, 2b of the seed layer 2 that needs to be etched away is etched and disappeared and the surface of the resin substrate 1 underneath is exposed as "just etching", and the time from the start of dipping to "just etching" is set as " T _JE ". In the above test piece is impregnated copper etching liquid, until the time is up to 3 times T _JE (T _JE × 3) so far. _{In addition, the time T JE} from the start of immersion to "just etching" can be changed according to the composition of the copper etching solution, the pH, the temperature of the etching bath, and the like.

Next, after the immersion time is T _JE , T _JE ×2, T _JE ×3, the test piece is taken out of the copper etching solution, and the test piece is cut parallel to its thickness direction. Next, using a digital microscope, the reduction amount L of each of the five circuits 3a and 3b in the cut surface of the test piece is measured, and the average value thereof is calculated. The results are shown in Table 2.

The meaning of each symbol in the "etching speed" column of Table 2 is as follows.

○: The etching rate is 1 μm/min or more and 3 μm/min or less.

△: The etching rate exceeds 3 micrometers/minute and is 7 micrometers/minute or less.

╳: The etching rate is 0 micron/min or more and 1 micron/min or less, or more than 7 micron/min.

Furthermore, the meaning of each symbol in the "reduction amount" field of Table 2 is as follows. Here, ΔL is the absolute value of the difference between the reduction amount of the circuit 3a and the reduction amount of the circuit 3b. When ΔL is large, it can be considered that at least Galvanic corrosion has occurred in the circuit 3a. ○: ΔL is 0 μm or more and 0.3 μm or less. △: ΔL exceeds 0.3 micrometer and is 1 micrometer or less. ╳: ΔL exceeds 1 micrometer, or at least one of the circuits 3a and 3b disappears and the nickel film 6 and the gold film 5 on the surface are peeled off.

※1：電路3a消失，而電路3b未消失 ※2：電路3a、3b中兩者皆消失[Table 2]

※1: Circuit 3a disappears, but circuit 3b does not disappear ※2: Both of circuits 3a and 3b disappear

<Evaluation> As shown in Table 2, can be understood in a copper etching solution of Example 1 to 3, even when reached after a 'just etching "three times the time until the time T _JE (T _JE × 3) of At the time point, the reduction amount was evaluated as "○". Accordingly be appreciated, in a copper etching solution of Examples 1 to 3, even at the time point reached after a 'just etching "three times the time until the time T _JE (T _JE × 3), in the circuit 3a Galvanic corrosion also did not occur.

Furthermore, in the copper etching solutions of Examples 1 to 3, the evaluation of the etching rate was "○" or "△". From this, it can be understood that the copper etching solutions of Examples 1 to 3 have excellent etching rates.

On the other hand, the copper etching solutions of Comparative Examples 1 to 3 are inferior to the copper etching solutions of Examples 1 to 3 in terms of reduction amount and etching speed. Even for the copper etching solution of Comparative Example 2, which has the highest evaluation of reduction in Comparative Examples 1 to 3, the time at which the time T _JE is three times (T _JE × 3) the time until the "right etching" has elapsed The evaluation of the reduction amount is "△". Thereby can be appreciated, a copper etching solution of Comparative Example 2, after the reach in "just etching" three times the time until the time T _JE (T _JE × 3) the time, place the gamma circuit 3a in Tiffany corrosion.

Reduction amount in Comparative Examples 1 to 3 Comparative Examples Evaluation second high copper etching solution 1 in the after "just etching" 2 times longer in time until the T _JE (T _JE × 2) reaches the point of time The evaluation of the reduction amount is "╳(※1)". Thereby can be appreciated, a copper etching solution of Comparative Example 1, after the reach of the "just etching" until time T _JE twice the time (T _JE × 2) the point in time, occurred in the gamma circuit 3a in Tiffany corrosion.

Moreover, the reduction amount in Comparative Example 1 to 3 copper etching liquid to the lowest evaluation of Comparative Example 3, in over a reach to reduce the amount of points until the time T _JE of time "just etch" rating to "╳ (※ 2 )”. From this, it can be understood that in the copper etching solution of Comparative Example 3, galvanic corrosion has occurred in the circuit 3a at the time point _{when the time T JE until the "just etching" has elapsed.} Furthermore, it can be understood that not only the circuit 3a, but also the circuit 3b Galvanic corrosion, the circuits 3a and 3b disappear and the nickel film 6 and the gold film 5 on the surfaces of the circuits 3a and 3b peel off.

It can be understood from the above results that the copper etching solutions of Examples 1 to 3 are more excellent in the effect of suppressing galvanic corrosion than the copper etching solutions of Comparative Examples 1 to 3.

Furthermore, in the copper etching solution of any one of Comparative Examples 1 to 3, the evaluation of the etching rate was "╳". From this, it can be understood that the etching rate of the copper etching solutions of Comparative Examples 1 to 3 is low.

Please refer to Table 1 to discuss the copper etching solutions of Examples 1 to 3 in detail. In the copper etching solution of Example 2, since the content of copper sulfate pentahydrate is reduced to about 1/6 of that of Example 1, the content of ammonia water is set to about 1/3 of that of Example 1, so that ammonia does not become excessive. It can be considered that in the copper etching solution of Example 2, since the amount of copper ammonia complexes produced is much lower than that of Example 1, the etching rate is much slower than that of Example 1, and the etching rate becomes 1 micron/min. Above and below 3 microns/min.

In the copper etching solution of Example 3, it can be considered that because the content of copper sulfate pentahydrate is the same as that of Example 1, and the ammonia water is about twice that of Example 1, the amount of copper ammonia complexes produced is much higher than that of Example 1. many. Moreover, the total content of ammonium sulfate and ammonium bicarbonate in Example 1 is 81.2 g/L, while the total content of ammonium sulfate and ammonium acetate in Example 3 is 49.5 g/L, and the content of ammonium sulfate is the same as that in the example. 1. But the content of ammonium acetate is about 1/2.7 of that of ammonium bicarbonate. It can be considered that in Example 3, by using ammonium acetate, the etching rate can be suppressed more than in Example 1, and the etching rate is 1 μm/min or more and 3 μm/min or less. 2. Use metal plate for etching test

2-1. Preparation of copper etching solution Here, a metal plate is used for etching test. First, the copper etching solutions of Examples 4 to 25 and Comparative Examples 4 to 9 shown in Tables 3 to 7 were prepared. As shown in Table 3, in the copper etching solutions of Examples 4 to 8 and Comparative Example 4, while the addition amount of ammonium sulfate was fixed at 50 g/liter, the addition amount of copper sulfate pentahydrate was 0.4 to 200 g/liter. The range of liters (in the range of 0.1-50 g/liter converted to copper), and the addition amount of 25% ammonia water changes in the range of 6-500 g/liter. Furthermore, in the copper etching solutions of Example 9 and Comparative Example 5, while the addition amount of ammonium sulfate was fixed at 250 g/L and the addition amount of 25% ammonia water was fixed at 500 g/L, copper sulfate pentahydrate The addition amount of sulphur is in the range of 250～300 g/L (converted to the range of 62.5～75 g/L in copper). As shown in Table 4, in the copper etching solutions of Examples 6, 10-15 and Comparative Examples 6-7, the addition amount of copper sulfate pentahydrate was fixed at 120 g/liter (converted to 30 g/liter of copper). Range) and the addition amount of 25% ammonia water is fixed at 150 g/L, while the addition amount of ammonium sulfate fluctuates in the range of 2.5 to 400 g/L. As shown in Table 5, in the copper etching solutions of Examples 16-17 and Comparative Example 8, based on the composition of the copper etching solution of Example 6, ammonium bicarbonate was added, and the addition amount was 0.5~250 g/L Changes within the range. As shown in Table 6, in the copper etching solutions of Examples 18-20 and Comparative Example 9, based on the composition of the copper etching solution of Example 6, ammonium acetate was added in an amount of 5 to 120 g/L. Changes within the scope. As shown in Table 7, in the copper etching solutions of Examples 21-25, based on the composition of the copper etching solution of Example 6, different kinds of ammonium salts were added at 20 g/L. 2-2. Etching test

Then, as described below, an etching test was performed using a metal plate. As shown in FIG. 4, first, the above-mentioned copper etching solution (the copper etching solutions of Examples 4-25 and Comparative Examples 4-9) 11 was put into a beaker 12, and heated in a constant temperature water tank 13 and heated with a stirrer 14 Stir. After that, the copper plate 15 and the gold plate 16 as the test piece were immersed in the copper etching solution 11 for 3 minutes. As the copper plate 15, an electrolytic copper foil having a thickness of 18 micrometers can be used. As the gold plate 16, a plate having a gold film with a thickness of 1 μm formed on a copper plate (not shown) by electroplating and a surface area of about 15 times that of the copper plate 15 can be used. The impregnation of the copper plate 15 and the gold plate 16 is performed in both the state where the copper plate 15 and the gold plate 16 are not conducting and the state where the conducting (lead) wire 17 is used. After that, when there is no conduction between the copper plate 15 and the gold plate 16 and when there is conduction, the etching rate on the copper plate 15 is calculated from the weight difference before and after the immersion. The results are shown in Tables 3-7. The meaning of each symbol in the "Etching Bath Stability" column of Tables 3 to 7 is as follows. Furthermore, the "-" in Tables 3 to 7 means that this component is not added, and since the etching bath cannot be established, the pH or etching rate is not measured. ○: The etching bath does not undergo self-decomposition, and the etching bath is very stable. ╳: The etching bath undergoes self-decomposition, so the etching bath cannot be established.

As shown in FIG. 4, in a state where the copper plate 15 and the gold plate 16 are conductive, galvanic corrosion may occur. On the other hand, in a state where the copper plate 15 and the gold plate 16 are not conductive, galvanic corrosion does not occur. It can be considered that in this etching test, when the copper plate 15 and the gold plate 16 are not conductive, the etching test using the circuit board W described above corresponds to the connection to the circuit 3a, which is a noble metal with respect to copper, and the copper plate When 15 and the gold plate 16 are in a conductive state, the etching test of the circuit board W described above corresponds to the circuit 3b that is not conductive to the noble metal with respect to copper. Therefore, this etching test can be considered to be a test performed by simplifying the etching test using the circuit board W described above. Furthermore, the quality of the etching rate depends on factors such as how the metal to be etched is manufactured or formed, or how much etching is necessary, and the judgment method is different. Therefore, in this etching test, the numerical value of the etching rate itself is not evaluated.

[table 3]

[Table 4]

[table 5]

[Table 6]

[Table 7]

<evaluation>

As shown in Table 3, in the copper etching solutions of Examples 4-9, when the copper plate 15 and the gold plate 16 are not conductive, and when they are conductive, there is almost no difference in the etching rate. From this, it can be understood that the copper etching solutions of Examples 4 to 9 are excellent in the effect of suppressing the galvanic corrosion. On the other hand, in the copper etching solution of Comparative Example 4, the etching speed is three times faster when conducting than when there is no conducting, and it can be understood that galvanic corrosion has occurred. Furthermore, in the copper etching solution of Comparative Example 5, the etching bath stability was low and the etching test could not be performed. It can be seen from the above that the copper content in the copper etching solution is 1~62.5 g/L and the content of 25% ammonia water is 10~500 g/L, which has an excellent effect of inhibiting Galvanic corrosion.

As shown in Table 4, in the copper etching solutions of Examples 6 and 10 to 15, when the copper plate 15 and the gold plate 16 are not conductive, and when they are conductive, there is almost no difference in the etching speed. From this, it can be understood that the copper etching solutions of Examples 6 and 10 to 15 are excellent in the effect of inhibiting Galvanic corrosion. On the other hand, in the copper etching solutions of Comparative Examples 6 to 7, the etching speed is 1.12 to 2.1 times faster in the case of conduction than in the case of no conduction, and it can be understood that the galvanic corrosion has occurred. It can be seen from the above that the content of ammonium sulfate in the copper etching solution is 5 to 300 g/L, and its effect of inhibiting the corrosion of Galvanic is very excellent.

As shown in Table 5, in the copper etching solutions of Examples 16 to 17, when the copper plate 15 and the gold plate 16 are not conducting, and when they are conducting, there is almost no difference in the etching rate. From this, it can be understood that the copper etching solutions of Examples 16 to 17 are excellent in the effect of inhibiting the corrosion of Galvanic. On the other hand, in the copper etching solution of Comparative Example 8, the etching bath stability was low and the etching test could not be performed. It can be seen from the above that the copper etching solution contains ammonium sulfate and ammonium bicarbonate as ammonium salts, and the content of ammonium bicarbonate is 0.5 to 200 g/L, which has an excellent effect of inhibiting Galvanic corrosion.

As shown in Table 6, in the copper etching solutions of Examples 18 to 20, when the copper plate 15 and the gold plate 16 are not conducting, and when they are conducting, there is almost no difference in the etching rate. From this, it can be understood that the copper etching solutions of Examples 18 to 20 are excellent in the effect of suppressing the corrosion of Galvanic. On the other hand, in the copper etching solution of Comparative Example 9, the etching speed was 23.5 times faster in the case of conduction than in the case of no conduction, and it is understood that galvanic corrosion occurred. It can be seen from the above that the copper etching solution contains ammonium sulfate and ammonium acetate as ammonium salts, and the content of ammonium acetate is 5-100 g/L, which has an excellent effect of inhibiting galvanic corrosion.

As shown in Table 7, in the copper etching solutions of Examples 21 to 25, when the copper plate 15 and the gold plate 16 are not conducting, and when conducting, there is almost no difference in the etching rate. From this, it can be understood that the copper etching solutions of Examples 21 to 25 are excellent in the effect of suppressing Galvanic corrosion. From the above, it can be seen that even when one of the ammonium salts selected from the group consisting of ammonium sulfate, ammonium nitrate, ammonium methanesulfonate, ammonium benzoate, ammonium lactate, and ammonium oxalate is combined, it is possible to achieve inhibition of gallium Etching solution with excellent effect of Vanney corrosion.

Based on the above results, if the copper etching solutions of Examples 4-25 are used to perform an etching test on the circuit board W shown in FIG. [Industrial Profitability]

According to the copper etching solution of the present invention, it is possible to suppress Galvanic corrosion and obtain a high etching rate. The copper etching solution according to the present invention can suppress galvanic corrosion, and is therefore suitable for, for example, etching of an object to be plated with copper that is connected to copper as a noble metal and copper that is not connected to the noble metal. Moreover, the copper etching solution according to the present invention can be applied to various technical fields such as electronic circuit boards and semiconductors.

1‧‧‧Resin substrate 2‧‧‧Seed layer 2a, 2b‧‧‧Seed layer 2 Parts that need to be etched away 3a, 3b‧‧‧Circuit 4.‧‧Electrode 5‧‧‧Gold film placed on the circuit 6‧‧‧Ni film on the circuit 7‧‧‧Ni film on the electrode 8‧‧‧Gold film on the electrode 9‧‧‧Inner circuit 11‧‧‧Copper etching solution 12‧‧‧Beaker 13 ‧‧‧ Constant temperature water tank 14‧‧‧Agitator 15‧‧‧Copper plate 16‧‧‧Gold plate17‧‧‧Wire L‧‧‧Reduced amount W‧‧‧Circuit board

[FIG. 1] A schematic cross-sectional view showing the shape of the circuit before being etched by the copper etching solution of this embodiment. [FIG. 2] is a schematic cross-sectional view showing the shape of the circuit after etching with the prior art copper etching solution. Fig. 3 is a schematic cross-sectional view showing the shape of the circuit etched with the copper etching solution of this embodiment. [Figure 4] is a schematic diagram illustrating the etching test method.

1‧‧‧Resin substrate

2‧‧‧Seed layer

3a, 3b‧‧‧circuit

4‧‧‧Electrode

5‧‧‧Gold film installed on the circuit

6‧‧‧Ni film installed on the circuit

7‧‧‧Ni film on the electrode

8‧‧‧Gold film set on the electrode

9‧‧‧Inner circuit

L‧‧‧reduction

Claims (4)

A copper etching solution, an alkaline copper etching solution, used to connect to copper that is a noble metal with respect to copper. It includes: 1~70g/L of copper; 25% ammonia water converted into 10~500g/L Ammonia; and 5~500 g/L of ammonium salt, the aforementioned ammonium salt is selected from the ammonium salt of inorganic acids such as ammonium sulfate, ammonium bicarbonate, and ammonium nitrate, the ammonium salt of sulfonic acid for ammonium methanesulfonate, Two or more of the ammonium salt of saturated fatty acid of ammonium acetate, the ammonium salt of aromatic carboxylic acid which is ammonium benzoate, the ammonium salt of hydroxy acid which is ammonium lactate, and the ammonium salt of dicarboxylic acid which is ammonium oxalate The ammonium salt. The copper etching solution described in item 1 of the scope of patent application, wherein the pH of the aforementioned copper etching solution is 7.8-11. The copper etching solution described in item 1 or 2 of the scope of patent application, wherein the copper etching solution contains ammonium sulfate and ammonium bicarbonate as the ammonium salt, and the content of the ammonium sulfate is 5 to 80 g/liter, and the carbonic acid The content of ammonium hydrogen is 0.5~200 g/L. The copper etching solution described in item 1 or 2 of the scope of patent application, wherein the copper etching solution contains ammonium sulfate and ammonium acetate as the ammonium salt, and the content of the ammonium sulfate is 5 to 80 g/l, and the ammonium acetate The content is 5~100g/L.

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