JP2010255063A - Etching solution for structure observation of copper or copper alloy, etching method and structure observation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an etching solution for structure observation with no special waste solution processing, usable as a micro corrosion etching solution and/or macro corrosion etching solution when observing a structure of a copper alloy with high oxidation sensitivity in which oxide formation tends to occur, high corrosion-resistant copper alloy, or high purity copper, high in safety of an ingredient, easy in handling or processing, without using special skill or expensive exclusive equipment, high in versatility, and with which a surface to be observed for clearly and easily observing a state of the structure or a crystal grain boundary is obtained. <P>SOLUTION: The etching solution for structure observation of copper or the copper alloy contains nitric acid, sulfuric acid, a copper sulfate salt, sodium hydroxide, and hydrogen peroxide as an initial composition for injecting into a bath. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an etching solution for observing the structure of copper or a copper alloy, an etching method, and a structure observing method, and in particular, a copper alloy having high oxidation sensitivity and easily generating oxide, a copper alloy having high corrosion resistance, or The present invention relates to a structure observation etching solution, an etching method, and a structure observation method that are suitably used for etching performed as a pretreatment when observing a structure such as high-purity copper.

Conventionally, in order to measure the crystal grain size of copper or copper alloy, observe the precipitation state, etc., the microscopic observation (microstructure observation) of the structural state of copper or copper alloy and the grain boundary has been performed. In general, when the microstructure of copper or copper alloy is observed, a pretreatment (micro-corrosion) for etching the surface to be observed using a micro-corrosive etching solution is performed.
Conventionally, when observing the solidification state of the casting material, the flow of the structure, etc. (macro structure observation), the work of etching the surface to be observed (macro-corrosion) using a macro-corrosion etching solution is often performed.

Examples of the micro-corrosive etching solution used for pretreatment of the surface to be observed made of copper or a copper alloy include m11 (ammonium hydroxide 25 ml, hydrogen peroxide (3%) 5 to 25 ml described in Non-Patent Document 1. , 25 ml of distilled water) A mixture of ammonia and hydrogen peroxide, which is equivalent to liquid, or m3 (10 g of copper (II) chloride, ammonium hydroxide is added until the precipitate is dissolved, 120 ml of distilled water). An aqueous solution containing copper II ammonium and ammonium hydroxide, m4 (sulfuric acid (1.84) 5 ml, sodium or potassium dichromate 10 g, distilled water 80 ml) equivalent sodium dichromate, nitric acid, hydrochloric acid and sodium chloride An aqueous solution containing Further, as a typical example of a micro-corrosive etching solution having high versatility and excellent etching characteristics, US domestic standard ASTM F68 17. An etchant composition using dichromic acid specified in TABLE 2 is known.
Moreover, as a macro-corrosion etching solution used in the macro structure observation for observing the solidification state of the material, the flow of the structure, etc., M2b (1 ml of nitric acid (1.40), 100 ml of distilled water), M3 (nitric acid (1.40)) 10 to 60 ml, distilled water 90 ml) and dilute nitric acid as shown in M4 (nitric acid (1.40) 50 ml, distilled water 50 ml) are frequently used.

 Further, as an etching method as micro-corrosion and macro-corrosion, generally, a method of rubbing the surface to be observed using absorbent cotton moistened with an etching solution is used.

Metal etching technology, Gunter Peugeo, Agne, February 20, 1991, 1st edition, 5th printing, P62-P65

  However, ASTM F68, which is an etchant m4 equivalent solution and highly versatile and has excellent etching characteristics. Since the micro-corrosive etching solution specified in TABLE 2 contains dichromic acid, it must be handled with great care within the facility where measures have been taken, and appropriate management is required for storage and disposal of raw material reagents and waste liquid treatment. It is essential. For this reason, there existed a problem that an installation, management, and processing cost increased. In addition, there are relatively few facilities and systems that can handle dichromic acid at sites that require observation of the metal structure, and it is generally considered safer and less polluting than dichromic acid. In many cases, only an etching solution having a low ability composed of various reagents can be used.

 In addition, when using an existing etchant, the suitability of the preferred etchant varies depending on the composition and processing history of the specimen, so it is necessary to select a suitable combination of the etchant and the specimen, and the performance is widely used. There was no etchant. In particular, Corson copper alloys containing nickel and silicon are subject to corrosion inhibition caused by nickel components contained in the alloy, so the appearance of crystal grain boundaries tends to be obscured and it may be difficult to observe the structure. It was. Also, copper alloys containing active components such as manganese and magnesium are highly susceptible to oxidation, causing abnormal discoloration and oxide formation called smut, making it impossible to observe the structure or polishing history during polishing. There were many problems such as the appearance of oxidation. Similarly, for high alloys containing a large amount of additive elements such as brass, corrosion inhibition and abnormal corrosion are often caused, making it impossible to observe the structure.

 In addition, when dilute nitric acid as shown in M2b, M3, and M4 is used as the macro-corrosion etching solution, corrosion inhibition, abnormal corrosion, or discoloration occurs, making it impossible to observe the structure, Sometimes it was not expressed.

  The present invention has been made in view of the above problems, and is a structure such as a copper alloy having high versatility, high oxidation sensitivity, and easily generating oxides, a copper alloy having high corrosion resistance, or high purity copper. Can be used as a micro- and / or macro-corrosion etchant when observing the material, has high component safety, is easy to handle and process, and does not require special skills or expensive dedicated equipment, An object of the present invention is to provide an etching solution for observing a structure, which can provide a surface to be observed that can clearly and easily observe a texture state and a crystal grain boundary, and does not require a special waste liquid treatment.

In addition, the present invention provides a macro-structure observation and / or a micro-structure observation after etching of a copper alloy which is highly susceptible to oxidation and easily generates oxide, a copper alloy having high corrosion resistance, or high purity copper. An object of the present invention is to provide an etching method capable of obtaining a corrosive surface suitable as a surface.
In addition, the present invention has a high oxidation sensitivity and is easy to generate oxides, a copper alloy with high corrosion resistance, or a structure such as high-purity copper, without using special skills or expensive dedicated equipment. An object of the present invention is to provide a tissue observation method capable of obtaining a good surface to be observed that can be observed clearly and easily efficiently.

 In order to solve the above problems, the present inventor pays attention to an etching agent having an etching action, a kind of a buffer material for adjusting an etching action by the etching agent, and a mechanism of hydroxylation and oxidation of copper or a copper alloy. The present invention has been conceived through extensive studies. That is, the present invention relates to the following.

The etching solution for observing the structure of copper or copper alloy of the present invention contains nitric acid, sulfuric acid, copper sulfate, sodium hydroxide and hydrogen peroxide as a building bath composition.
The etching solution for observing the structure of copper or copper alloy of the present invention contains nitric acid as an etching agent, and contains copper sulfate, sulfuric acid and sodium hydroxide as a buffer material for adjusting the etching action, and is etched. In order to promote the formation of a hydroxide film that suppresses or promotes the oxidation of the observation surface, it contains sodium hydroxide, which is a hydroxide as a neutralizing agent, and also contains hydrogen peroxide in anticipation of the radical nature of the hydroxyl group. Therefore, it is highly versatile, has high susceptibility to oxidation, and is susceptible to micro-corrosion when observing the structure of copper alloys, copper alloys with high corrosion resistance, or high-purity copper. It can be used as an etchant and / or a macro-corrosive etchant, and the structure and crystal grain boundaries are clear and easy without using special skills or expensive dedicated equipment. Observable becomes which the observed surface is obtained.
In addition, the copper or copper alloy structure observation etching solution of the present invention has high component safety, is easy to handle and process, and does not require any special waste liquid treatment.

 In the copper or copper alloy structure observation etching solution of the present invention, the copper sulfate salt is preferably a copper sulfate pentahydrate salt.

 In the etching solution for observing the structure of copper or copper alloy according to the present invention, the composition of the building bath is 0.43 to 0.57 mol / l nitric acid (18 to 24 ml / l), 0. 51-0.68 mol / l (27-36 ml / l), copper sulfate pentahydrate salt 0.005-0.05 mol / l (1.4-13 g / l), sodium hydroxide 0.03-0. It is preferable that 035 mol / l (1.0 to 1.4 g / l), hydrogen peroxide 1 to 2 mol / l are contained, and the remainder is made of water (18.2 MΩ ultrapure water).

 The etching method of the present invention is characterized in that copper or a copper alloy is etched using the structure observation etching solution of the present invention.

 Further, the structure observation method of the present invention comprises immersing an observation surface made of copper or a copper alloy in the etching solution for structure observation of the present invention, and etching the observation surface while conducting ultrasonic waves in the etching solution for tissue observation. And an observing step of observing the structure of the observed surface after etching.

The etching solution for observing the structure of copper or copper alloy of the present invention contains nitric acid, sulfuric acid, copper sulfate salt, sodium hydroxide and hydrogen peroxide as a building bath composition, so that it acts on copper or copper alloy. However, it can be appropriately adjusted by the copper sulfate salt, sulfuric acid, and sodium hydroxide, which are buffer materials, so that the etching action on copper or a copper alloy can function well.
Therefore, the structure observation etching solution of the present invention is highly versatile, has high oxidation sensitivity, and observes a structure such as a copper alloy that easily generates oxides, a copper alloy having high corrosion resistance, or high purity copper. Can be used as a micro-corrosion etchant and / or a macro-corrosion etchant, and when this is used to etch copper or a copper alloy, copper or copper can be used without special skills or expensive dedicated equipment. It is possible to obtain a surface to be observed in which the structure of the alloy and the grain boundaries can be clearly and easily observed.

  Moreover, the copper or copper alloy structure observation etching solution of the present invention has a higher component safety and is easier to handle and process than special etching solutions containing dichromic acid. It is preferable because it does not require expensive dedicated equipment or special waste liquid treatment.

 Further, the etching method of the present invention is a method of etching copper or copper alloy using the structure observation etching solution of the present invention, and the etching action on copper or copper alloy is appropriately adjusted by the buffer material. The copper or copper alloy will be etched with relatively slow corrosion. For this reason, by using the etching method of the present invention, macrostructure observation is performed by performing etching of a copper alloy that is highly susceptible to oxidation and easily generates oxide, a copper alloy having high corrosion resistance, or high-purity copper. And / or a corroded surface suitable as a surface to be observed for microstructure observation is obtained.

Further, the structure observation method of the present invention includes immersing a surface to be observed made of copper or a copper alloy in the structure observation etching solution of the present invention, and etching the surface to be observed while conducting ultrasonic waves in the tissue observation etching solution. A copper alloy that has high oxidation sensitivity and is likely to generate oxides, or a copper alloy that has high corrosion resistance, or an etching process that performs an observation process for observing the structure of the observed surface after etching. Without using special skills or expensive dedicated equipment when observing macrostructures such as high-purity copper, when performing microstructural observations, or performing microstructural observations after performing macrostructural observations, A good surface to be observed can be obtained in which the texture state and the grain boundary can be clearly and easily observed.
Further, in the structure observation method of the present invention, even when there are a plurality of surfaces to be observed made of copper or a copper alloy which is a sample to be observed, the etching process is performed on the plurality of samples at once Therefore, as compared with the case where individual samples are etched individually, the etching process can be performed easily and efficiently, and the structure observation of a plurality of samples can be performed efficiently.

FIG. 1 is a photomicrograph of the surface to be observed after etching. FIG. 2 is a photomicrograph of the surface to be observed after etching. FIG. 3 is a photograph of the surface to be observed after etching. FIG. 4 is a photomicrograph of the observed surface after etching. FIG. 5 is a photomicrograph of the observed surface after etching. FIG. 6 is a photomicrograph of the observed surface after etching.

"Etching solution for tissue observation"
The etching solution for observing the structure of copper or copper alloy of the present invention contains nitric acid, sulfuric acid, copper sulfate salt, sodium hydroxide and hydrogen peroxide as a building bath composition.
Since the structure observation etching solution of the present invention has wide versatility, it is not particularly limited as copper or a copper alloy to be etched using the structure observation etching solution of the present invention. For example, 6N high purity Pure copper, Cu-Si-Zn brass, Corson-type copper alloys, etc. that are difficult to etch with existing liquids / existing methods, general oxygen-free copper, tough pitch copper, phosphorous deoxidized copper, etc. Is mentioned. Examples of the Corson copper alloy include a copper alloy containing Cu, Ni, Si, and Mg and a copper alloy containing Cu, Ni, Si, Zn, and Sn.

 In the structure observation etching solution of the present invention, the copper sulfate salt is preferably a copper sulfate pentahydrate salt. The copper sulfate pentahydrate salt functions as a buffer material that appropriately adjusts the etching action on copper or copper alloy, and is preferable.

 When the copper sulfate salt is a copper sulfate pentahydrate salt, the contents of nitric acid, sulfuric acid, copper sulfate salt, sodium hydroxide and hydrogen peroxide contained in the structure observation etching solution of the present invention are shown below. A range is preferable. That is, the composition of the bath is 0.43 to 0.57 mol / l (18 to 24 ml / l) nitric acid, 0.51 to 0.68 mol / l (27 to 36 ml / l), copper sulfate in one liter. Pentahydrate salt 0.005-0.05 mol / l (1.4-13 g / l), sodium hydroxide 0.03-0.035 mol / l (1.0-1.4 g / l), peroxidation It is preferable that hydrogen is contained in an amount of 1 to 2 mol / l and the balance is water (18.2 MΩ ultrapure water).

 When the content of nitric acid is less than 0.43 mol / l, the etching action of the etching solution for structure observation becomes insufficient, the etching rate is too slow, and the time required for etching becomes long, and the crystal grain boundaries are clearly defined. May not be able to appear, and a good surface to be observed may not be obtained. Further, when the content of nitric acid exceeds 0.57 mol / l, the etching action of the structure observation etching solution becomes excessive, and the function as a buffer material by copper sulfate, sulfuric acid and sodium hydroxide may be insufficient. There is a risk that the crystal grain boundary will be unclear.

 If the sulfuric acid content is less than 0.51 mol / l, the function as a buffer material by sulfuric acid becomes insufficient, and corrosion inhibition, abnormal corrosion, discoloration, etc. may occur, and the crystal grain boundaries may become unclear. Arise. On the other hand, if the content of sulfuric acid exceeds 0.68 mol / l, the function as an acid by sulfuric acid becomes excessive, which may cause discoloration or over-etching, resulting in failure to obtain a good surface to be observed.

 The content of the copper sulfate pentahydrate salt contained in the etching solution for structure observation is determined according to characteristics such as oxidation sensitivity of the material to be etched, and is 0.005 to 0.05 mol / l ( The range of 1.4 to 13 g / l) is preferred. When the content of copper sulfate pentahydrate salt is less than 0.005 mol / l, the etching action of the etching solution for structure observation becomes excessive, and corrosion inhibition, abnormal corrosion, discoloration, etc. occur, or the structure observation is hindered. There is a risk that the crystal grain boundaries may become unclear due to the formation of oxides. On the other hand, if the content of the copper sulfate pentahydrate salt exceeds 0.05 mol / l, the etching action of the structure observation etching solution may be insufficient.

 The content of the copper sulfate pentahydrate salt is, for example, 0.005 to 0.010 mol / l in the case of etching copper or a copper alloy with low oxidation sensitivity that does not contain Mn, Mg, Zn or the like. It is more preferable to set it as the range of 1.4-2.6 g / l). When etching copper or copper alloys with low oxidation sensitivity, the content of copper sulfate pentahydrate salt should be within the above range to prevent corrosion, abnormal corrosion, or discoloration while maintaining a sufficient corrosion rate. It is possible to sufficiently prevent the generation of oxides that interfere with the structure observation.

 However, when the content of copper sulfate pentahydrate is 0.010 mol / l or less, a copper alloy containing Mn, Mg, Zn, etc., which is highly susceptible to oxidation and easily generates oxides, is etched. Therefore, there is a risk that the inhibition of corrosion, abnormal corrosion, discoloration, and formation of oxides that hinder the structure observation cannot be sufficiently suppressed. Even when etching such a copper alloy that is prone to oxide formation, the content of copper sulfate pentahydrate salt is appropriately increased in the range of 0.05 mol / l or less to inhibit corrosion. Abnormal corrosion, discoloration, and formation of oxides that interfere with tissue observation can be sufficiently prevented.

 Sodium hydroxide functions as a neutralizing agent for the structure observation etching solution and promotes the formation of a hydroxide film that adjusts the oxidizing action on the surface to be observed. If the sodium hydroxide content is less than 0.03 mol / l, corrosion inhibition, abnormal corrosion, discoloration, etc. may occur, and oxides that interfere with the structure observation may be generated, resulting in poor grain boundaries. There is a fear of clarity. On the other hand, if the content of sodium hydroxide exceeds 0.035 mol / l, the etching action of the etching solution for structure observation becomes insufficient, and crystal grain boundaries cannot be clearly shown, and a good surface to be observed is obtained. There is a risk that it will not be obtained.

 If the hydrogen peroxide content is less than 1 mol / l, the effect of promoting the formation of a hydroxide film by containing hydrogen peroxide cannot be sufficiently obtained, and the excessive etching action by the structure observation etching agent is not obtained. It becomes impossible to suppress, and there is a fear that the crystal grain boundary becomes unclear. In addition, if the hydrogen peroxide content exceeds 2 mol / l, the etching action of the structure observation etching solution becomes excessive and acts strongly as an oxidizing agent for sulfuric acid, etc., which causes discoloration and overetching. Therefore, there is a risk that a good surface to be observed cannot be obtained.

"Etching method, microstructure observation method"
Next, a structure observation method for observing the structure of the surface to be observed after etching the surface to be observed made of copper or a copper alloy (micro corrosion or macro corrosion) using the structure observation etching solution of the present invention will be described. .
A method for etching (micro-corrosion or macro-corrosion) an observation surface made of copper or a copper alloy using the structure observation etching solution of the present invention in order to perform macro-structure observation or micro-structure observation is not particularly limited. However, for example, a method of immersing a surface to be observed made of copper or a copper alloy in an etching solution for structure observation (hereinafter referred to as “first method”) or an etching solution for structure observation from copper or a copper alloy. A method of immersing the surface to be observed and etching the surface to be observed while conducting ultrasonic waves in the tissue observation etching solution (hereinafter referred to as “second method”), or the first method and the second method. For example, a combination of both methods can be used, and the method can be appropriately determined according to the characteristics of the copper or copper alloy to be etched, the purpose of the structure observation, or the like.

Specifically, for example, when the surface to be observed made of copper or a copper alloy is subjected to macro-corrosion using the structure observation etching solution of the present invention, a good surface to be observed can be obtained only by performing the first method. It is done.
However, in order to obtain a better surface to be observed when the surface to be observed made of a copper alloy containing Mn, Mg, Zn, etc., which has high oxidation sensitivity and is likely to generate oxide, is macro-corroded. It is preferable to perform the second method after performing the first method.

 In addition, when the surface to be observed made of copper or a copper alloy is micro-corroded using the structure observation etching solution of the present invention, the second method is preferably performed, but only the first method may be performed. When performing only the first method using the structure observation etching solution of the present invention, copper or a copper alloy is etched at a relatively slow corrosion rate, so that a relatively smooth corrosion surface is obtained. For this reason, the observation surface obtained by performing only the first method is suitable for microstructural observation at a low magnification of, for example, about 200 times, but is also suitable for macrostructural observation.

 Moreover, when performing the macro structure observation and the micro structure observation of the surface to be observed made of copper or a copper alloy using the structure observation etching solution of the present invention, for example, it was obtained by performing the first method. It is preferable to observe the observed surface obtained by performing the second method on the observed surface after observing the observed surface with the macro structure and then observing the macro structure. When the macro structure observation and the micro structure observation of the surface to be observed are performed in this manner, a surface to be observed suitable for observation can be obtained in both the macro structure observation and the micro structure observation. In addition, the method for observing the macro structure and the micro structure on the surface to be observed in this manner is particularly suitable for observing the structure using a video microscope.

Since the etching solution for structure observation of copper or copper alloy of this embodiment contains nitric acid, sulfuric acid, copper sulfate salt, sodium hydroxide and hydrogen peroxide as a building bath composition, etching for copper or copper alloy is performed. Since the action is appropriately adjusted by the copper sulfate salt, sulfuric acid and sodium hydroxide which are buffer materials, the etching action on copper or copper alloy can be made to function well.
More specifically, since the structure observation etching solution of this embodiment contains sodium hydroxide and hydrogen peroxide, when the surface to be observed is etched (micro corrosion or macro corrosion) using this, the surface to be observed Prior to oxidative corrosion, the surface of the surface to be observed is suppressed or promoted by the action of hydroxide ions and hydrogen peroxide remaining free from sodium hydroxide, which is a neutralization buffer. A hydroxide film is generated, and the corrosion rate of the surface to be observed due to the corrosiveness of the surface to be observed is appropriately adjusted.

 As a result, the etching solution for structure observation of the present embodiment is a copper alloy having high corrosion resistance even if the surface to be etched is made of a copper alloy that is highly susceptible to oxidation and easily generates oxide. Whether it is made of copper or high-purity copper, the corrosion of the surface to be observed progresses slowly and substantially uniformly, so that the crystal grain boundary on the surface to be observed can appear clearly. It is thought that it will be high. Therefore, the structure observation etching solution of this embodiment can be preferably used as a micro-corrosion etching solution and / or a macro-corrosion etching solution that is performed when observing the structure of copper or a copper alloy. When the alloy is etched, a surface to be observed can be obtained that can clearly and easily observe the structure state and grain boundaries of copper or copper alloy without using special skills or expensive dedicated equipment.

 The etching method of this embodiment is a method of etching copper or copper alloy (micro corrosion and / or macro corrosion) using the structure observation etching solution of this embodiment, and has an etching action on copper or copper alloy. However, since it is appropriately adjusted by the buffer material, the copper or copper alloy is etched with relatively slow corrosion. For this reason, by using the etching method of the present embodiment, a macro structure is obtained by etching a copper alloy that is highly susceptible to oxidation and that easily generates oxide, a copper alloy that has high corrosion resistance, or high-purity copper. A corrosion surface suitable as an observation surface for observation and / or microstructure observation is obtained.

 The etching method of this embodiment is a method of etching copper or copper alloy using the structure observation etching solution of this embodiment, and copper or copper alloy is etched at a relatively slow corrosion rate. For example, even when a copper alloy having high oxidation sensitivity is subjected to macro-corrosion, over-etching hardly occurs, and a surface to be observed for macro-structure observation, which is a good corroded surface after etching, can be obtained.

 Further, in the etching method of the present embodiment, since the etching action on copper or copper alloy is appropriately adjusted by the buffer material, a leveling effect in which copper or copper alloy is dissolved relatively uniformly is obtained, and intentionally healthy. It can be etched until the layer is reached.

 In addition, the structure observation method of this embodiment is obtained by immersing a surface to be observed made of copper or a copper alloy in the structure observation etching solution of this embodiment, and etching the surface to be observed while conducting ultrasonic waves in the structure observation etching solution. A copper alloy that has high oxidation sensitivity and easily generates oxides, or a copper alloy that has high corrosion resistance, or an etching process that performs an observation process for observing the structure of the surface to be observed after etching. When performing macro-structure observation of high-purity copper, etc., when performing micro-structure observation, when performing micro-structure observation after performing macro-structure observation, without using special skills or expensive dedicated equipment. A good surface to be observed in which the state and crystal grain boundaries can be clearly and easily observed can be obtained. This is because the surface to be observed is immersed in the tissue observation etching solution while conducting ultrasonic waves, so that a fresh tissue observation etching solution is always forcibly supplied to the surface to be observed and the corrosion is uniformly accelerated. In addition, it is considered that the accumulated accumulation of the oxide film that can also be a passive film is less likely to occur.

 Further, in the structure observation method of the present embodiment, even when there are a plurality of surfaces to be observed made of copper or copper alloy, which are samples to be observed, the etching process is performed on the plurality of samples at once. Therefore, as compared with the case of individually etching individual samples, the etching process can be performed easily and efficiently, and the structure observation of a plurality of samples can be performed efficiently.

 On the other hand, for example, when etching a plurality of samples using a conventional etching method in which the surface to be observed is rubbed with an absorbent cotton moistened with an etching solution, the individual samples are individually etched. It was hanging.

In addition, in the conventional etching method in which the surface to be observed is rubbed with absorbent cotton moistened with an etching solution, the surface to be observed and the absorbent cotton are in contact with each other, and the foreign matter attached to the surface to be observed is observed with the absorbent cotton. The surface to be observed may be scratched by being rubbed against the surface. In particular, when oxide is generated on the surface to be observed by etching, the oxide is inevitably spread on the surface to be observed by rubbing the surface to be observed with absorbent cotton moistened with an etching solution. As a result, the discoloration of the surface to be observed may be enlarged, or polishing of the oxide may cause new scratches on the surface to be observed.
In addition, in the conventional etching method in which the surface to be observed is rubbed with absorbent cotton moistened with an etching solution, the rubbing speed and pressure, the amount of etching on the surface to be observed, etc. vary depending on the skill of the operator, etc. However, there is a problem that it is not possible to rely on craftsmanship when etching materials that are difficult to etch, especially difficult to etch.

 On the other hand, in the tissue observation method of the present embodiment, since it is not necessary to contact the surface to be observed with anything other than the tissue observation etching solution, the surface to be observed is caused by bringing the surface to be observed into contact with the absorbent cotton. No scratches or etching irregularities due to the skill of the operator rubbing the surface to be observed.

 The structure observation etching solution of the present invention can be suitably used not only as a copper or copper alloy structure observation etching solution, but also when, for example, washing copper or copper alloy.

"Example 1"
A specimen made of Cu-Ni-Si-Zn-Sn is placed in a beaker with the surface to be observed facing up, immersed in the etching solution 1 shown in Table 1, and the specimen is 120 while conducting ultrasonic waves in the etching solution. Etched for 2 seconds. Thereafter, washing with pure water and drying with a dryer were performed, and the microstructure of the observed surface was observed using an inverted metal microscope (Nippon Optical Epishot). The result is shown in FIG.

  FIG. 1 is a photomicrograph of the surface to be observed after etching. As shown in FIG. 1, when the etching solution 1 was used, there was no appearance of flaw lines due to etching, and crystal grain boundaries could be clearly shown.

"Example 2"
A test body made of Cu—Ni—Si—Mg was etched in the same manner as in Example 1 except that the etching solution 2 shown in Table 1 was used. Thereafter, the microstructure of the surface to be observed was observed in the same manner as in Example 1. The result is shown in FIG.
FIG. 2 is a photomicrograph of the surface to be observed after etching. As shown in FIG. 2, when the etching solution 2 was used, there was no appearance of flaw lines due to etching on the surface to be observed, and crystal grain boundaries could be clearly shown.

"Example 3"
A specimen made of an OFC (ordinary oxygen-free copper) composition processed product was immersed in the etching solution 1 shown in Table 1, and the surface to be observed was etched for 30 minutes. Thereafter, cleaning with pure water and drying with a dryer were performed, and the macro structure of the surface to be observed was observed. The result is shown in FIG. FIG. 3 is a photograph of the surface to be observed after etching.
Thereafter, the observed surface on which the macro structure was observed was observed in the same manner as in Example 1. The results are shown in FIG. FIG. 4 is a photomicrograph of the observed surface after etching.
As shown in FIG. 3, it is possible to observe a precise macrostructure that allows detailed observation of the flow state and thermal effect of the material by plastic working, and it is also possible to observe a microstructure as shown in FIG.

“Comparative Example 1”
A test specimen similar to that in Example 1 was etched by a method of rubbing the surface to be observed using absorbent cotton moistened with an etching solution using the etching solution 3 shown in Table 1 which is a liquid corresponding to m11. Thereafter, the microstructure of the surface to be observed was observed in the same manner as in Example 1. The result is shown in FIG.
FIG. 5 is a photomicrograph of the surface to be observed after etching. As shown in FIG. 5, when the etching solution 3 was used, the crystal grain boundary was unclear.

“Comparative Example 2”
A test specimen similar to that of Example 2 was etched by a method of rubbing the surface to be observed using absorbent cotton moistened with an etching solution using the etching solution 3 shown in Table 1 which is a liquid corresponding to m11. Thereafter, the microstructure of the surface to be observed was observed in the same manner as in Example 1. The result is shown in FIG.
FIG. 6 is a photomicrograph of the observed surface after etching. As shown in FIG. 6, when the etching solution 3 was used, a flaw line resulting from etching was generated on the surface to be observed, and the crystal grain boundary was unclear.

Claims (5)

  An etching solution for observing the structure of copper or copper alloy, which contains nitric acid, sulfuric acid, copper sulfate salt, sodium hydroxide and hydrogen peroxide as a building bath composition.  The said copper sulfate salt is a copper sulfate pentahydrate salt, The etching liquid for structure | tissue observation of the copper or copper alloy of Claim 1 characterized by the above-mentioned. In one liter, the composition is
Nitric acid 0.43-0.57 mol / l (18-24 ml / l),
Sulfuric acid 0.51-0.68 mol / l (27-36 ml / l),
Copper sulfate pentahydrate salt 0.005-0.05 mol / l (1.4-13 g / l),
Sodium hydroxide 0.03-0.035 mol / l (1.0-1.4 g / l),
Containing hydrogen peroxide 1-2 mol / l,
3. The etching solution for observing the structure of copper or copper alloy according to claim 2, wherein the remainder is made of water (18.2 MΩ ultrapure water).   An etching method comprising etching copper or a copper alloy using the structure observation etching solution according to any one of claims 1 to 3. A surface to be observed made of copper or a copper alloy is immersed in the structure observation etching solution according to any one of claims 1 to 3, and the surface to be observed is etched while conducting ultrasonic waves in the structure observation etching solution. A structure observation method comprising: an etching step for performing an observation step, and an observation step for performing a structure observation of the observed surface after etching.