KR20120029634A - Iridium plating solution and method of plating using the same - Google Patents

Abstract

PURPOSE: An iridium plating solution and a plating method thereof are provided to effectively restrict cracks on an iridium-plated film because the plating solution contains one or more of Fe(Iron), Co(Cobalt), Ni(Nickel), and Cu(Copper). CONSTITUTION: An iridium plating solution uses an iridium compound which is made by mixing one or more kinds of compounds in iridium complex salt, wherein the compounds are selected from the group consisting of saturated mono carboxylic acid, saturated mono carboylate, saturated dicarboxylic acid, saturated dicarboylate, saturated hydroxyl carboxylic acid, saturated hydroxyl carboylate, amid, and urea.

Description

Iridium plating solution and its plating method {IRIDIUM PLATING SOLUTION AND METHOD OF PLATING USING THE SAME}

The present invention relates to an iridium plating solution and a plating method thereof.

Iridium is a metal having high hardness and exhibiting excellent corrosion resistance against high concentrations of acids, aqua regia or halogens. And the application range is industrially widely used not only as a decoration but also as a hardening | curing agent of a predetermined metal, a catalyst, and a material, such as an anticorrosive material and an electrical contact.

As the iridium plating solution in the case of using this iridium, a saturated monocarboxylic acid, a saturated monocarboxylic acid, a saturated dicarboxylic acid, a saturated dicarboxylic acid salt, a saturated hydroxycarboxylic acid, a saturated hydroxycarboxylic acid salt, to an iridium (III) complex salt whose anion component is halogen is used. The iridium plating liquid which uses what was added and stirred the 1 or more types of compound chosen from the group which consists of a amide | amido and an urea as an iridium compound is known (refer patent document 1).

This iridium plating liquid is stable and difficult to decompose, and is effectively used as a practical iridium plating liquid having high current efficiency and fast plating speed.

However, also in such an excellent iridium plating liquid, the following point is made regarding the plating property. For example, when used in electronic components for electrical connection such as lead pins (see Patent Document 2), cracks may occur in the iridium plated coating, and a phenomenon may occur in which electrical characteristics cannot be sufficiently satisfied. In electronic components such as lead pins, iridium plating is usually applied to rhodium in the base, but rhodium in the base is reduced and the iridium plated coating is reduced with the price rise of a rare metal such as rhodium. Correspondence to thick plating is examined. As described above, when the iridium plating film is thickly formed, cracks are particularly remarkable in the conventional iridium plating solution, and electrical characteristics may not be satisfied.

Japanese Patent Laid-Open No. 6-316786 Japanese Patent Laid-Open No. 7-21867

This invention is made | formed under such circumstances, and an object of this invention is to propose the iridium plating liquid which can easily form the iridium plating film in which the generation | occurrence | production of the crack was suppressed the most, and its plating method.

This invention consists of saturated monocarboxylic acid, saturated monocarboxylic acid, saturated dicarboxylic acid, saturated dicarboxylic acid, saturated hydroxycarboxylic acid, saturated hydroxy carboxylate, amide, and urea to the iridium (III) complex salt whose anion component is halogen. The iridium plating solution using the iridium compound obtained by adding and stirring one or more compounds selected from the group is characterized by containing at least one or more of Fe, Co, Ni, and Cu. Since at least any metal of Fe, Co, Ni, and Cu exists in a plating liquid, generation | occurrence | production of the crack in an iridium plating film is suppressed effectively.

In the iridium plating solution of the present invention, the content of at least one or more of Fe, Co, Ni, and Cu is preferably 0.01 g / L to 10 g / L. If it is less than 0.01 g / L, a crack will be easy to generate, and if it exceeds 10 g / L, crystal growth will become unstable.

It is preferable that any of these Fe, Co, Ni and Cu metals are contained in the plating liquid as soluble metal salts.

As for the iridium plating liquid in this invention, it is preferable that iridium contains 1-200 g / l in metal iridium concentration, More preferably, it is 10-20 g / l. When the iridium concentration is less than 1 g / l, the upper limit of the current density becomes smaller, making it difficult to provide practically. When the iridium concentration is more than 200 g / l, the iridium becomes saturated and the iridium cannot be dissolved. Examples of the iridium (III) complex salt include hexachloroiridium (III) acid salt, hexabromoiridium (III) acid salt, hexafluoroiridium (III) acid salt, preferably hexabromoiridium (III) acid salt and hexachloroiridium ( III) Sodium acid salt etc. can be employ | adopted.

In addition, the at least one compound selected from the group consisting of saturated monocarboxylic acid, saturated monocarboxylic acid salt, saturated dicarboxylic acid, saturated dicarboxylic acid salt, saturated hydroxycarboxylic acid, saturated hydroxycarboxylic acid salt, amide and urea is 0.001 to 1.0 mol / It is preferable to add L, More preferably, it is 0.01-0.2 mol / L addition. As the compound, for example, acetic acid, disodium malonate, oxalic acid, and the like can be employed, and preferably sodium malonate. And the addition amount was made into 0.001-1.0 mol / L because the effect by addition hardly appears when it is less than 0.001 mol / L, and when it exceeds 1.0 mol / L, precipitation is prevented.

The iridium plating solution according to the present invention may contain a buffer for adjusting pH, for example, boric acid, sulfamic acid, and the like, as necessary.

In the iridium plating method according to the present invention, the conditions are pH 1-8, temperature 50-98 ° C, current density 0.01-3.0 A / dm ² , preferably pH 4-6, temperature 80-90 ° C, current density. It is used under the operating conditions of 0.1 ~ 0.8A / dm ² . The pH of 1 to 8 is because when the pH is less than 1, the upper limit of the current density becomes smaller and becomes impractical. When the pH is higher than 8, hydroxides are generated and precipitation occurs. If the temperature is lower than 50 ° C, precipitation becomes extremely difficult to occur, and if the temperature is higher than 98 ° C, evaporation of water becomes violent, which is not practically desirable. In addition, when the current density is lower than 0.01 A / dm ² , the precipitation rate is extremely small, and when the current density is higher than 3.0 A / dm ² , hydrogen is generated and the precipitates do not precipitate.

According to this invention, the iridium plating film in which the generation | occurrence | production of the crack was suppressed as much as possible can be formed.

1 is a photograph of the plating surface observation of Example 1.
2 is a photograph of the plating surface observation without metal addition.
Figure 3 is a photograph of the plated surface observation of Example 2.
4 is a photograph of observation of a plating surface with a Co content of 20.0 g / L in Example 2. FIG.
5 is a photograph of the plating surface observation of Example 3. FIG.
6 is a photograph of a plated surface observation of 15.0 g / L Ni content in Example 3. FIG.
7 is a photograph of the plating surface observation of Example 4.
8 is a photograph of the plating surface observation of Example 5. FIG.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described in detail, referring an Example.

Example 1

In this Example 1, the case where Fe is added to an iridium plating liquid is demonstrated. The liquid composition of this Example 1 is as follows.

15 g / L sodium hexabromoiridium (III) acid (in terms of iridium metal)

Boric Acid 40g / L

Sodium malonate 0.02mol / L

Ferrous sulfate heptahydrate 0.01 g / L (iron metal conversion)

In Example 1, as the iridium compound, dibasic sodium malonic acid as a "dicarboxylate" was added to the above hexabromoiridium (III) acid, and the mixture was stirred for 1 hour with a magnetic stirrer while being maintained at 85 ° C in a hot bath. Used one. Iron sulfate hexahydrate was added to the iridium plating solution, and the plating solution contained 0.01 g / L of Fe.

And the gold strike plating process was performed to the test piece of the brass piece of 2cmx2cm, and the 3.0-micrometer-thick iridium plating film was formed after the gold plating process of 1.0 micrometer thickness. Plating process conditions were pH 3.5-4.0, liquid temperature 80-85 degreeC, and current density of 0.5 A / dm <^2> .

About the coated iridium plating film, plating property was observed using the metal microscope (400 times). The result is shown in FIG.

In addition, the thing in which the iridium plating film was formed by the blank iridium plating liquid which none of Fe, Co, Ni, and Cu were added for the comparison was produced. The plating conditions of this blank were made like the case where Fe was contained. The results are shown in Fig.

As shown in FIG. 2, what covered with the iridium plating liquid containing no Fe confirmed that many cracks generate | occur | produced on the surface. On the other hand, in the case of the iridium plating liquid containing Fe as shown in FIG. 1, the crack was hardly confirmed.

In addition, the content of Fe was changed to 0.005 g / L, 0.01 g / L, 0.5 g / L, 5.0 g / L, and 10 g / L, and the occurrence of cracks was confirmed. Although it confirmed, the generation | occurrence | production of a crack was not confirmed at 0.01 g / L or more.

Example 2

In Example 2, the case where Co is added to the iridium plating solution will be described. The liquid composition of this Example 2 is as follows.

15 g / L sodium hexabromoiridium (III) acid (in terms of iridium metal)

Boric Acid 40g / L

Sodium citrate 0.05mol / L

Cobalt sulfate heptahydrate 0.5 g / L (cobalt metal conversion)

In Example 2, as the iridium compound, dibasic sodium citrate as "hydroxycarboxylate" was added to the hexabromoiridium (III) acid, and stirred for 1 hour with a magnetic stirrer while maintaining the temperature at 85 ° C in a hot bath. Used one. Cobalt sulfate was added to this iridium plating liquid, and 0.5 g / L of Co was contained in the plating liquid.

And the gold strike plating process was performed to the test piece of the brass piece of 2cmx2cm, and the 3.0-micrometer-thick iridium plating film was formed after the gold plating process of 1.0 micrometer thickness. Plating process conditions were pH 3.5-4.0, liquid temperature 80-85 degreeC, and current density of 0.5 A / dm <^2> .

About the coated iridium plating film, plating property was observed using the metal microscope (400 times). The results are shown in Fig.

As shown in FIG. 3, in the case of the iridium plating liquid containing Co, cracks were hardly confirmed.

In addition, the content of Co was changed to 0.005 g / L, 0.01 g / L, 0.5 g / L, 5.0 g / L, and 10 g / L, and the crack generation was confirmed. Although it confirmed, the generation | occurrence | production of a crack was not confirmed at 0.01 g / L or more.

Moreover, content of Co was made into 20.0 g / L, and plating property was observed using the metal microscope (400 times). The result is shown in FIG. At Co content 20.0 g / L, no normal precipitation was obtained.

Example 3:

In Example 3, the case where Ni is added to the iridium plating solution will be described. The liquid composition of this Example 3 is as follows.

15 g / L sodium hexabromoiridium (III) acid (in terms of iridium metal)

Boric Acid 40g / L

Oxalic acid 0.05mol / L

Nickel Sulfate Heptahydrate 0.5g / L (In terms of Nickel Metal)

In Example 3, as the iridium compound, an oxalic acid as a "dicarboxylate" was added to the hexabromoiridium (III) acid salt, followed by stirring for 1 hour with a magnetic stirrer while maintaining the temperature at 85 ° C in a hot bath. . Nickel sulfate hexahydrate was added to the iridium plating solution to contain 0.5 g / L of Ni in the plating solution.

And the gold strike plating process was performed to the test piece of the brass piece of 2cmx2cm, and the 3.0-micrometer-thick iridium plating film was formed after the gold plating process of 1.0 micrometer thickness. Plating process conditions were pH 3.5-4.0, liquid temperature 80-85 degreeC, and current density of 0.5 A / dm <^2> .

About the coated iridium plating film, plating property was observed using the metal microscope (400 times). The result is shown in FIG.

As shown in FIG. 5, in the case of the iridium plating solution containing Ni, cracks were hardly confirmed.

In addition, when the content of Ni was changed to 0.005 g / L, 0.01 g / L, 0.5 g / L, 5.0 g / L, and 10 g / L, and the occurrence state of the crack was confirmed, crack generation occurred at 0.005 g / L. Although it confirmed, the generation | occurrence | production of a crack was not confirmed at 0.01 g / L or more.

Moreover, Ni content was 15.0 g / L and plating property was observed using the metal microscope (400 times). The result is shown in FIG. Normal precipitation was not obtained in Ni content of 15.0 g / L.

Example 4:

In Example 4, the case where Cu is added to the iridium plating solution will be described. The liquid composition of this Example 4 is as follows.

15 g / L sodium hexabromoiridium (III) acid (in terms of iridium metal)

Boric Acid 40g / L

Acetic acid 0.02mol / L

Copper sulfate pentahydrate 0.01 g / L (copper metal conversion)

In Example 4, as the iridium compound, an acetic acid as "monocarboxylate" was added to the above hexabromoiridium (III) acid, and the mixture was stirred for 1 hour with a magnetic stirrer while being maintained at 85 ° C in a hot bath. . Copper sulfate pentahydrate was added to this iridium plating liquid, and 0.01 g / L of Cu was contained in the plating liquid.

And the gold strike plating process was performed to the test piece of the brass piece of 2cmx2cm, and the 3.0-micrometer-thick iridium plating film was formed after the gold plating process of 1.0 micrometer thickness. Plating process conditions were pH 3.5-4.0, liquid temperature 80-85 degreeC, and current density of 0.5 A / dm <^2> .

About the coated iridium plating film, plating property was observed using the metal microscope (400 times). The results are shown in Fig.

As shown in FIG. 7, cracks were hardly confirmed in the case of the iridium plating liquid containing Cu.

In addition, when the content of Cu was changed to 0.005 g / L, 0.01 g / L, 0.5 g / L, and 1.0 g / L, and the occurrence state of the crack was confirmed, the occurrence of crack was confirmed at 0.005 g / L. The occurrence of crack was not confirmed at 0.01 g / L or more.

Example 5:

In Example 5, the case where Co is added to the iridium plating solution will be described. The liquid composition of this Example 5 is as follows.

5 g / L sodium hexachloroiridium (III) acid (in terms of iridium metal)

Boric Acid 20g / L

Sodium malonate 0.10mol / L

Cobalt sulfate heptahydrate 0.5 g / L (cobalt metal conversion)

In Example 5, as the iridium compound, the sodium hexachloroiridium (III) acid was added to sodium borohydride as dicarboxylate, and stirred for 1 hour with a magnetic stirrer while being maintained at 85 ° C in a hot bath. . Cobalt sulfate was added to this iridium plating liquid, and 0.5 g / L of Co was contained in the plating liquid.

And the gold strike plating process was performed to the test piece of the brass piece of 2cmx2cm, and the 3.0-micrometer-thick iridium plating film was formed after the gold plating process of 1.0 micrometer thickness. Plating process conditions were pH 3.5-4.0, liquid temperature 80-85 degreeC, and current density of 0.2 A / dm <^2> .

About the coated iridium plating film, plating property was observed using the metal microscope (400 times). The result is shown in FIG.

As shown in FIG. 8, in the case of the iridium plating solution containing Co, cracks were hardly confirmed.

Example 6:

In the sixth embodiment, the case where Ni is added to the iridium plating solution and the plating conditions are changed will be described. The liquid composition of this Example 6 is as follows.

10 g / L sodium hexabromoiridium (III) acid (in terms of iridium metal)

Boric Acid 30g / L

Oxalic acid 0.05mol / L

Nickel Sulfate Heptahydrate 0.5g / L (In terms of Nickel Metal)

In Example 6, as the iridium compound, oxalic acid as a dicarboxylate was added to the above hexabromoiridium (III) acid, and the mixture was stirred for 1 hour with a magnetic stirrer while being maintained at 85 ° C in a hot bath. Nickel sulfate hexahydrate was added to the iridium plating solution to contain 0.5 g / L of Ni in the plating solution.

And the gold strike plating process was performed to the test piece of the brass piece of 2cmx2cm, the gold plating process of 1.0 micrometer thickness was formed, the 3.0-micrometer-thick iridium plating film was formed, and precipitation efficiency was measured. Plating process conditions were pH 2.0-8.5, liquid temperature 40-95 degreeC, and current density of 0.01-2.0 A / dm <^2> .

Precipitation efficiency at the time of changing the pH to liquid temperature of 85 degreeC and current density of 0.5 A / dm <^2> was measured.

At pH 0.5, the precipitation efficiency became 0% and did not precipitate. At pH 3.0, the precipitation efficiency was 85% and no crack was observed. The precipitation efficiency was 95% -100% until pH 4.0-7.0, and no crack was confirmed. Further, precipitation of hydroxide occurred at pH 8.5.

Next, the current density was set to 0.5 A / dm ² and pH 3.5, and the precipitation efficiency when the bath temperature was changed was measured.

At bath temperature 40 degreeC, precipitation efficiency did not precipitate to 0%. At bath temperature of 50 degreeC, precipitation efficiency was 35% and the crack was confirmed. Precipitation efficiency was 40%-60%, and the crack was not confirmed until bath temperature 60 degreeC-70 degreeC. Precipitation efficiency was 90-100% at the bath temperature of 80 degreeC-95 degreeC, and the crack was not confirmed. Moreover, when bath temperature was raised to 99 degreeC, evaporation of the water from a plating bath became intense, and it became difficult to perform stable plating process.

Next, the bath temperature was 85 ° C and pH 3.5, and the precipitation efficiency when the current density was changed was measured.

At the current density of 0.01 A / dm ² , the precipitation efficiency was 50%, and no crack was observed. At current density of 0.02 A / dm ^{2 to} 1.0 A / dm ² , the precipitation efficiency was 90 to 100%, and no crack was observed. At a current density of 1.5 A / dm ² , the precipitation efficiency was 60%, and no crack was observed. At a current density of 3.0 A / dm ² , the precipitation efficiency was 20% and cracks were observed. In addition, when the current density was raised to 3.5 A / dm ² , hydrogen was generated, and normal precipitation was not obtained.

It is possible to easily form an iridium plated film in which the occurrence of cracks is suppressed as much as possible.

Claims (3)

1 selected from the group consisting of saturated monocarboxylic acid, saturated monocarboxylic acid salt, saturated dicarboxylic acid, saturated dicarboxylic acid salt, saturated hydroxycarboxylic acid, saturated hydroxycarboxylic acid salt, amide, urea to iridium (III) complex salt whose anion component is halogen In the iridium plating liquid using the iridium compound obtained by adding and stirring a compound of species or more,
An iridium plating solution containing at least one of Fe, Co, Ni, and Cu. The method of claim 1,
An iridium plating solution in which at least one or more of Fe, Co, Ni, and Cu is 0.01 g / L to 10 g / L. The iridium plating method of plating on the conditions of pH 1-8, the temperature of 50-98 degreeC, and the current density of 0.01-3.0 A / dm <^2> using the plating liquid of Claim 1 or 2.

Images