TW201623687A - Reduction-type electroless gold plating solution and electroless gold plating method using said plating solution - Google Patents

Abstract

The purpose of the present invention is to provide an electroless gold plating solution which does not contain harmful substances and is capable of achieving good wire bonding performance, while suppressing corrosion of a base metal. In order to achieve this purpose, an electroless plating solution that contains a water-soluble gold compound, citric acid or a citrate, ethylenediaminetetraacetic acid or an ethylenediaminetetraacetate, hexamethylenetetramine and a chain polyamine containing three or more amino groups and an alkyl group having three or more carbon atoms is employed as a reduction-type electroless gold plating solution which is used for the purpose of forming an electroless gold plating film on the surface of an object to be plated by means of electroless plating.

Description

Reductive electroless gold plating solution and electroless gold plating method using the same

The invention of the present application relates to an electroless gold plating solution, an electroless gold plating method using the electroless gold plating solution, and an electroplated product which is subjected to electroplating treatment by the electroless gold plating method. More specifically, it relates to a regenerative electroless gold plating technique which can perform direct electroplating treatment on the surface of a substrate to be plated.

In recent years, there has been a demand for high-performance or multi-functions of electronic devices. On the other hand, printed circuit boards used in these electronic devices have been required to be thinner and lighter. In order to cope with the reduction in size and thickness, the circuit pattern is miniaturized, and a high degree of mounting technology is required as the circuit pattern is miniaturized. Generally, in the field of printed circuit boards, techniques for bonding components or terminal parts have established techniques for using solder or wire-bonding.

Since the purpose of ensuring the connection reliability of the solder or wire-bonding bonding is ensured, the plating process is performed to form the surface of the wiring portion of the circuit portion and the terminal portion of the circuit on the printed circuit board. deal with. As a plating process, nickel plating, palladium plating, and the like are sequentially performed on a circuit pattern formed by a metal such as low-resistance copper. Gold-plated technology. The nickel-plated film prevents the copper circuit from being etched by the solder, and the palladium-plated film prevents the nickel constituting the nickel-plated film from diffusing to the gold-plated film. Next, the gold plating film is formed in order to achieve low resistance and obtain good solder wettability.

The prior art of the plating technique described above is, for example, Patent Document 1 to Patent Document 3 shown below. The electroless gold plating method described in Patent Document 1 is a method of forming a gold plating film on an electroless gold plating solution containing a reductant on nickel, and forming a gold plating film on the nickel as a catalyst for electroless gold plating.

Further, in the electroless gold plating method described in Patent Document 2, an electroless nickel plating film is formed on a surface to be plated of an electronic component through a catalyst, and an electroless nickel plating film is formed on the electroless nickel plating film, and Further, on the electroless palladium plating film, a method of forming an electroless gold plating film of an electroless gold plating film plating layer is formed, and the electroless gold plating bath is used by using the first electroless gold plating of the electroless gold plating bath. It comprises a water-soluble gold compound, a complexing agent, formaldehyde and/or formaldehyde bisulfite addenda and a specific amine compound to form an electroless gold plating film.

Further, the non-electrolytic gold plating liquid for a palladium film described in Patent Document 3 can form an electroless gold plating solution directly forming a gold plating film on a palladium film, and contains a water-soluble gold compound, a reductant, and a complexing agent. It is composed of an aqueous solution, and the reductant contains at least one compound selected from the group consisting of formaldehyde hydrogen sulfite, white powder, and hydrazine.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 05-222541

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2008-266668

[Patent Document 3] Japanese Patent Laid-Open Publication No. 2008-174774

However, in the electroless gold plating method of Patent Document 1, the gold plating film is formed by depositing gold by the oxidation potential difference between the nickel as the base and the gold ions in the plating bath, and therefore, the gold is corroded by the dissolution of the base nickel. The base nickel, as a result, has a problem that nickel diffuses into the gold plating film. When nickel is diffused into the gold plating film, there is a problem that the gold-gold bonding strength of wire-bonding is lowered. In order to prevent this accident, in Patent Document 1, an electroless gold plating film is formed on the gold plating film, and the thickness of the gold film is increased to suppress a decrease in wire-bonding property. However, this technique has to form a replacement gold plating film, and therefore, there is a problem that the cost is high and the productivity is deteriorated.

In addition, in the state of the electroless gold plating method described in the above-mentioned Patent Document 2 or the non-electrolytic gold plating liquid for the palladium film described in Patent Document 3, it is possible to suppress corrosion of nickel which is a base metal, but The electroless gold plating bath contains a highly toxic formaldehyde or formaldehyde bisulfite add-on, so it is not easy to ensure the safety of the plating process.

Therefore, in the market, it is possible to suppress corrosion of the base metal and achieve good wire-bonding property without requiring an electroless gold plating solution containing a harmful substance.

In order to solve the above problems, the inventors of the present invention conducted research with all of their efforts, and as a result, provided the electroless gold plating liquid, the electroless gold plating method, and the electroplated product shown below.

The regenerative electroless gold plating solution of the present invention is a regenerative electroless gold plating solution which is formed on an electroless gold plating film on the surface of a substrate to be coated, and is characterized in that it contains a water-soluble gold compound, citric acid or citrate. Ethyldiaminetetraacetic acid or ethyldiaminetetraacetate, hexamethylenetetramine, and a chain polyamine having an alkyl group having 3 or more carbon atoms and 3 or more amine groups.

The regenerative electroless gold plating solution of the present invention preferably has a pH of 7.0 to a pH of 9.0.

In the reductive electroless gold plating solution of the present invention, the above-mentioned chain polyamine is preferably 3,3'-diamino-N-methyldipropylamine or N,N'-bis(3-aminopropyl). ) Ethyl diamine.

It is more preferable that the reductive electroless gold plating liquid system of the present invention contains a ruthenium compound as a precipitation promoter.

The electroless gold plating method of the present invention is characterized in that an electroless gold plating film is formed on the surface of the object to be plated by using the above-mentioned reductive electroless gold plating solution.

In the electroless gold plating method of the present invention, it is preferable that the surface of the object to be plated is any one of copper, palladium, gold or nickel.

Further, in the electroless gold plating method of the present invention, it is preferable that the surface of the object to be plated is provided with an electroless palladium film formed on the surface of the electroless nickel plating film.

The electroplated article of the invention is characterized in that: Electroless gold plating is performed to perform electroless gold plating.

The regenerative electroless gold plating solution of the present invention comprises: a water-soluble gold compound, citric acid or citrate, ethylenediaminetetraacetic acid or ethyldiaminetetraacetate, hexamethylenetetramine And a chain polyamine containing an alkyl group having 3 or more carbon atoms and 3 or more amine groups, and it is easy to thicken the gold plating film on the surface of the object to be plated.

Further, even in the state in which the nickel-plated film/palladium-plated film/gold-plated film provided on the electrical connection portion is formed by using the reductive electroless gold plating solution of the present invention, the film thickness of the palladium plating film is not affected. A gold-plated film can be formed rapidly on the surface of the palladium-plated film. Further, according to the regenerative electroless gold plating solution of the present invention, even in the state in which the electroless gold plating film is formed on the surface of the electroless palladium film formed on the surface of the electroless nickel plating film, it is possible to In the state in which the gold plating film is formed, the dissolution of nickel is more remarkably suppressed, and diffusion of nickel to the gold plating film can be prevented. Therefore, according to the regenerative electroless gold plating solution of the present invention, it is possible to provide a gold plating film capable of achieving a high degree of wire-bonding bonding reliability.

In addition, the reductive electroless gold plating liquid of the present invention further improves the stability of the solution compared to the conventional electroless gold plating liquid, and does not contain formaldehyde or formaldehyde bisulfite addition which is highly toxic, so that it is easy to ensure electroplating treatment. The safety of the work.

Further, the gold-removing reaction of the reductive electroless gold plating liquid of the present invention occurs only on the surface of gold, palladium, nickel, copper or the like which can become a catalyst core, and It occurs in the part without the catalyst core, so the selection of the precipitation system becomes good. Therefore, it is possible to prevent the gold plating film from being formed in a portion where no gold is required to be deposited, which is advantageous in terms of saving raw materials.

Fig. 1 is a graph showing the relationship between the plating time and the plating film thickness of the reductive electroless gold plating film of the sample group 1A for execution.

Fig. 2 is a graph showing the relationship between the plating time and the plating film thickness of the reductive electroless gold plating film of Example 2.

Fig. 3 is a graph showing the relationship between the film thickness of the underlying palladium plating film and the deposition rate of the gold plating film in the state in which the electroless gold plating solution of Example 1 and Comparative Example 1 was used.

Fig. 4 is an electron micrograph (x 10000 and × 30000) of the reductive electroless gold plating film of the sample 1A-2.

Fig. 5 is an electron micrograph (x30000) of the reductive electroless gold plating film of the sample 2-2 and the comparative example 2.

Fig. 6 is an electron micrograph (x5000) of the surface of the nickel-plated film after the rectifying type electroless gold plating film and the electroless palladium plating film were peeled off from the plating film of the sample 1A-2 for execution.

Fig. 7 is an electron micrograph (x3000) of the surface of the nickel-plated film after the rectifying type electroless gold plating film was peeled off from the plating film of the sample for the execution of the sample 2-2 and the comparative example 2.

Fig. 8 is a cross-sectional observation photograph (x30000) of the reductive electroless gold plating film of the sample 1A-6.

Fig. 9 is an electron micrograph (x500) of the end portion and the center portion of an electroplated article in which an electroplated film was formed under the same conditions as those for carrying out the sample 1A-6.

Fig. 10 is a graph showing the relationship between the amount of nickel dissolved in the gold plating solution in the state in which the electroless gold plating solution of Example 1 and Comparative Example 1 was used.

Fig. 11 is a graph showing the film thickness deviation of the electroless gold plating film of Example 2 and Comparative Example 2.

Fig. 12 is a graph showing the wire-bonding characteristics of the electroless gold plating film of Example 2 and Comparative Example 2.

Hereinafter, embodiments of the regenerative electroless gold plating solution of the present invention, the electroless gold plating method using the plating solution, and the electroplated product processed by the method will be separately described.

1. The reductive electroless gold plating solution of the present invention

The regenerative electroless gold plating liquid of the present invention is formed by forming an electroless gold plating film on the surface of the object to be plated, and is characterized by: "water-soluble gold compound", "citric acid or citrate", and "ethylidene" Diaminetetraacetic acid or ethyldiaminetetraacetate, "hexamethylenetetramine", and "chain polyamine having an alkyl group having 3 or more carbon atoms and 3 or more amine groups". Hereinafter, each component will be described separately.

(1) Water-soluble gold compounds

The water-soluble gold compound used in the reductive electroless gold plating solution of the present invention can be dissolved in the plating solution, and if the concentration is specified, the water solubility of any of the cyanide-based gold salt and the non-cyanide-based gold salt can be used. Gold compound. The water-soluble gold compound as a specific cyanide gold salt may be exemplified by a cyanide gold. Potassium, cyanide gold sodium, cyanide gold ammonium, and the like. Further, as the water-soluble gold compound of the specific non-cyanide gold salt, a chlorinated gold salt, a gold sulfite salt, a gold thiosulfate salt or the like can be exemplified. Even among these, it is particularly preferable to use potassium gold cyanide. Further, the water-soluble gold compound may be used singly or in combination of two or more. Further, the water-soluble gold compound is not limited to the gold compound exemplified herein.

The concentration of the water-soluble gold compound in the reductive electroless gold plating solution of the present invention is preferably from 0.0025 mol/L to 0.0075 mol/L. Since the concentration of the water-soluble gold compound is less than 0.0025 mol/L, the deposition rate of the gold plating film is slow, and it is not easy to obtain a gold plating film having a desired film thickness. Since the concentration of the water-soluble gold compound exceeds 0.0075 mol/L, the stability of the plating solution may be lowered, and it is also disadvantageous for economic reasons.

(2) Citric acid or citrate

The reductive electroless gold plating solution of the present invention contains citric acid or citrate. These citric acid or citrate are used as a complexing agent which can form a coordination compound with gold ions. The concentration of citric acid or citrate in the reductive electroless gold plating solution of the present invention is preferably from 0.05 mol/L to 0.15 mol/L. Since the concentration of these citric acid or citrate as a complexing agent is less than 0.05 mol/L, gold is precipitated in the plating solution, which deteriorates the stability of the solution because it is in a state exceeding 0.15 m/L. Next, the formation of a coordination compound is excessively performed to lower the rate of precipitation of gold, and it is not easy to obtain a gold plating film having a desired film thickness.

(3) Ethyldiaminetetraacetic acid (EDTA) or ethyldiaminetetraacetate

The reductive electroless gold plating solution of the present invention contains exoethyldiaminetetraacetic acid (EDTA) or ethylidene diamine tetraacetate. Ethyldiamine tetraethylene The acid or exoethyldiaminetetraacetate is a complexing agent used in combination with the aforementioned citric acid or citrate. The concentration of the extended ethylenediaminetetraacetic acid or the ethylidenediamine tetraacetate in the reductive electroless gold plating solution of the present invention is preferably 0.03 mol/L to 0.1 mol/L. Because the concentration of ethyldiaminetetraacetic acid or ethyldiaminetetraacetate as a complexing agent is less than 0.03 mol/L, gold is precipitated in the plating solution, which deteriorates the stability of the solution, and because In the state of more than 0.1 mol/L, the formation of a coordination compound is excessively performed, the rate of precipitation of gold is lowered, and a gold plating film having a desired film thickness is not easily obtained.

(4) hexamethylenetetramine

The reductive electroless gold plating solution of the present invention contains hexamethylenetetramine. The gold ion in the hexamethylenetetramine-based plating solution is used as a reductant for depositing gold on the surface of the object to be plated.

The concentration of hexamethylenetetramine in the reductive electroless gold plating solution of the present invention is preferably from 0.003 mol/L to 0.009 mol/L. Since the concentration of hexamethylenetetramine is less than 0.003 mol/L, the deposition rate of the gold plating film becomes slow, and the gold plating film of the desired film thickness is not easily obtained, and when it exceeds 0.009 m/L, it is rapidly performed. The reversion reaction has an abnormal precipitation of the state of the gold salt in the plating solution, which deteriorates the stability of the solution, and is also disadvantageous for economic reasons.

(5) Chain polyamine

Further, the reductive electroless gold plating solution of the present invention contains a chain polyamine containing an alkyl group having 3 or more carbon atoms and 3 or more amine groups. The chain polyamine acts as an amine compound for supplementing the reductant of the gold ion in the plating solution. As the chain polyamine system, 3,3'-diamino-N-methyldipropylamine, N,N'-bis(3-aminopropyl)ethylidene diamine or the like can be specifically used. because In view of the performance or economy of the obtained plating film, it becomes particularly good.

The concentration of the chain polyamine in the reductive electroless gold plating solution of the present invention is preferably 0.02 mol/L to 0.06 mol/L. The concentration of the chain polyamine can be in the range of 0.02 mol/L to 0.06 mol/L without affecting the film thickness of the base metal film and maintaining a high deposition rate. Further, the adhesion around the gold plating film can be improved, and the gold plating film can be thickened to 0.2 μm or more. In addition, the stability of the solution can be remarkably improved.

(6) Other ingredients

In the reductive electroless gold plating solution of the present invention, in addition to the aforementioned water-soluble gold compound, citric acid or citrate, ethylenediaminetetraacetic acid or ethyldiaminetetraacetate, hexamethylenetetramine, Further, a chain-like polyamine having an alkyl group having 3 or more carbon atoms and three or more amine groups may further contain a precipitation accelerator. As a series of precipitation promoters used herein, a ruthenium compound or a lead compound is used. From the viewpoint of thick film formation of the obtained gold plating film, it is preferable to use a ruthenium compound.

The concentration of the ruthenium compound as the precipitation promoter in the reductive electroless gold plating solution of the present invention is preferably from 1 mg/L to 10 mg/L. When the concentration of the ruthenium compound as the precipitation promoter is less than 1 mg/L, it is not easy to form a thick film of the gold plating film. Further, when the concentration of the ruthenium compound as the precipitation promoter exceeds 10 mg/L, the above thick film formation cannot be achieved, which is disadvantageous in terms of economy.

The reductive electroless gold plating liquid of the present invention may further contain an additive such as a pH adjuster, an oxidation preventive agent, a surfactant, or a gloss agent in addition to the above-mentioned essential components.

The pH adjusting agent is not particularly limited, and examples thereof include potassium hydroxide, sodium hydroxide, an aqueous ammonia solution, sulfuric acid, and phosphoric acid. The reductive electroless gold plating solution of the present invention is preferably maintained at a pH of 7.0 to a pH of 9.0 by using a pH adjusting agent. Because the pH of the non-electroless gold plating solution is lower than 7.0, the plating solution is easily decomposed. When the pH is higher than 9.0, the plating solution is excessively stabilized to slow the deposition rate of the plating, and the thick film of the gold plating film It takes a lot of time. Further, it is also possible to carry out a plating treatment of a material to be plated which is made of a material which is weaker than an alkali, by adjusting the pH value to 7.0 to 9.0. Further, as an additive such as an oxidation preventive agent, a surfactant, a gloss agent or the like, a conventional one can be used.

(7) Plating conditions

The gold plating conditions using the reductive electroless gold plating solution of the present invention are not particularly limited, but the liquid temperature is preferably 40 ° C to 90 ° C, particularly preferably 75 ° C to 85 ° C. The plating time is also not particularly limited, but it is preferably 1 minute to 2 hours, particularly preferably 2 minutes to 1 hour.

The reductive electroless gold plating liquid of the present invention is as described above by using a water-soluble gold compound, citric acid or citrate, ethylenediaminetetraacetic acid or ethyldiaminetetraacetate, and hexamethylene A tetraamine and a chain polyamine having an alkyl group having 3 or more carbon atoms and 3 or more amine groups are used as an essential component, and an electroless plating method is applied to easily increase adhesion gold plating on the surface of the object to be plated. The thickness of the film.

Further, even in the state in which the nickel plating film/palladium plating film/gold plating film provided on the electrical connection portion is formed, the film thickness of the palladium plating film can be obtained by using the reductive electroless gold plating solution of the present invention. Influence, plating The surface of the palladium film rapidly forms a gold-plated film. Further, even in the state in which an electroless gold plating film is formed on the surface of the electroless palladium film formed on the surface of the electroless nickel plating film, it is possible to form by using the regenerative electroless gold plating solution of the present invention. The state of the replacement type gold plating film further suppresses the elution of nickel more significantly, and prevents the diffusion of nickel to the diffusion of the gold plating film. Therefore, according to the regenerative electroless gold plating solution of the present invention, it is possible to provide a gold plating film which can achieve a high degree of wire-bonding bonding reliability.

Further, the reductive electroless gold plating liquid of the present invention has a higher stability of the solution than the conventional electroless gold plating liquid. For example, in the state in which the plating solution is continuously electroplated, as the indicator of the deterioration of the plating solution, the metal period is exceeded (MTO), and the gold in the plating solution at the time of the bath is completely precipitated as one cycle. ). In the state of the conventional regenerative electroless gold plating solution, the MTO is 2.0 to 3.0 cycles, and the reductive electroless gold plating liquid of the present invention can achieve an MTO of 5.0 cycles or more.

Further, the reductive electroless gold plating liquid of the present invention does not contain the highly toxic formaldehyde or formaldehyde bisulfite addition contained in the conventional rectifying electroless gold plating liquid, and therefore, it is easy to ensure the safety of the plating treatment work.

Further, the gold-removing reaction of the reductive electroless gold plating liquid of the present invention occurs only on the surface of gold, palladium, nickel, copper, or the like which can serve as a catalyst core, and does not occur in the portion having no catalyst core, so that precipitation is selected. The sex system has become good. Therefore, it is possible to prevent the formation of the gold plating film on the portion where no gold is required to be deposited, which is advantageous in that the raw material can be saved.

2. Electroless gold plating method

Next, the electroless gold plating method of the present invention will be described. In the electroless gold plating method of the present invention, an electroless gold plating treatment is performed on the surface of the object to be plated using any of the above-described reductive electroless gold plating solutions to form a gold plating film. In the electroless gold plating method, similar to the usual refraction type electroless plating treatment method, a plating treatment is performed by immersing the object to be deposited in an electroless gold plating solution.

In the electroless gold plating method of the present invention, it is preferable that any of copper, palladium, gold, and nickel is present on the surface of the object to be treated. If any of copper, palladium, gold, and nickel is present on the surface of the object to be plated, the form of existence may be in any state. It is particularly preferable to use any one of the object to be plated by copper or a film composed of copper, palladium, gold, nickel or an alloy containing these metals on the surface of the object to be plated. For example, as an alloy containing these metals, gold cobalt is mentioned. Gold, palladium, nickel, copper or an alloy containing these metals is the base metal of the electroless gold plating of the present invention, and the metal or alloy is a hexamethylene group as a reductant contained in the above-mentioned reductive electroless gold plating solution. Tetraamine acts as a catalyst. As the film formed on the surface of the object to be plated, it is particularly preferable to use an electroless palladium film, a replacement gold plating film or a copper plating film. For example, in the state where electroless nickel plating is performed on the surface of the circuit portion of the printed circuit board or the terminal portion, it is preferable to form an electroless palladium film on the surface of the electroless nickel plating film. If the palladium plating film is formed on the surface of the nickel plating film, it is particularly effective in preventing the diffusion of the nickel plating film to the diffusion of the gold plating film.

3. Electroplating products

Next, the electroplated product of the present invention will be described. this invention The electroplated product is characterized in that an electroless gold plating treatment is performed on the surface of the object to be plated by using the electroless gold plating solution of any one of the above-mentioned electroless gold plating methods on the surface of the object to be plated. Even in this case, it is preferable to use an electroless gold plating solution having a pH of 7.0 to 9.0 to perform an electroless gold plating treatment on the surface of the object to be plated. Further, if any one of copper, palladium, gold, and nickel is present on the surface of the object to be plated, the form of its existence may be in any state. It is particularly preferable to use any one of the object to be plated by copper or a film composed of copper, palladium, gold, nickel or an alloy containing these metals on the surface of the object to be plated. Even in the case, it is preferable to use an electroless palladium film, a replacement gold plating film or a copper plating film as the film formed on the surface of the object to be plated. In particular, it is preferable to form an electroless nickel plating film as a substrate to be plated with an electroless palladium film on the surface as the underlayer of the electroless palladium film. Since the plating treatment using the above-described reductive electroless gold plating solution is particularly suitable for the formation of an electroplated film at an electrical connection portion.

The embodiment of the present invention described above is an embodiment of the present invention, and it is a matter of course that the present invention can be appropriately modified without departing from the scope of the invention.

In the following, the first example and the second embodiment of the gold-plated film produced by using the regenerative electroless gold plating solution of the present invention, and the comparative example 1 of the gold-plated film produced by using the replacement electroless gold plating solution are listed, and the conventional example is used. The present invention will be more specifically described in Comparative Example 2 of a gold-plated film produced by a regenerative electroless plating solution. However, the present invention is not limited to the embodiments described below, and will be described in advance for reminding.

[Example 1]

In the first embodiment, a re-type electroless gold plating solution to which the present invention is applied is used, and a copper plate is used as a substrate, and an electroplated film composed of an electroless nickel plating film/electroless palladium plating film/electroless gold plating film is formed on the substrate. .

Adjustment of the regenerative electroless gold plating liquid: In the following, the composition of the reductive electroless gold plating liquid used in the present embodiment is shown. The plating conditions (pH, liquid temperature) and composition are also shown.

Preparation of Electroplated Film: The sample to be used as the additional plating film of Example 1 was composed of the sample group 1A for execution and the sample group 1D for execution. The sample group 1A for the implementation of the sample group 1A for the execution is different from the film thickness of the electroless palladium film.

The sample group 1A for execution is composed of the sample 1A-1 for execution and the sample 1A-6 for execution, and each sample for application is formed on the surface of a copper plate to form an electroless nickel plating film having a film thickness of 5 μm, and then the electroless nickel plating film is used. The surface of the nickel plating film was formed to form an electroless palladium film having a film thickness of 0.1 μm. Then, a reductive electroless gold plating film is formed on the surface of the electroless palladium film by using the above-described reductive electroless gold plating solution in accordance with the conditions of each plating time. Specifically, the implementation test The conditions of the plating time in the formation of the sample 1A-6-return type electroless gold plating film are 10 minutes, 20 minutes, 30 minutes, 40 minutes, 50 minutes, and 60 minutes, and an additional gold plating film is obtained. Sample.

The sample group 1B for the reaction is composed of the sample 1B-1 for the execution of the sample 1B-6, and the film thickness of the electroless palladium film is 0.2 μm, which is the same as the sample group 1A for the execution. Production. In addition, each of the sample 1B-1 to the sample 1B-6 for execution is the same as the sample 1A-1 to the sample 1A-6 for execution, so that the conditions of the plating time when the reductive electroless gold plating film is formed are different. .

The sample group 1C for the reaction was composed of the sample 1C-1 for the execution of the sample 1C-6, and the film thickness of the electroless palladium film was 0.4 μm, which was the same as the sample group 1A for the execution. Production. In addition, each of the sample 1C-1 to the sample for execution 1C-6 is the same as the sample 1A-1 for execution 1A-6, and the conditions for the plating time when the non-electroless gold plating film is formed are different. .

The sample group 1D for the reaction is composed of the sample 1D-1 for the execution of the sample 1D-6, and the film thickness of the electroless palladium film is 0.6 μm, which is the same as the sample group 1A for the execution. Production. In addition, each of the sample 1D-1 to the sample 1D-6 for execution is the same as the sample 1A-1 to the sample 1A-6 for execution, so that the conditions of the plating time when the reductive electroless gold plating film is formed are different. .

[Example 2]

In Example 2, the reductive electroless gold plating solution similar to that of Example 1 was used, and a copper plate was used as a substrate on which an electroless nickel plating film was formed. Electroplated film composed of a film/displacement type electroless gold plating film/return type electroless gold plating film. The sample of the additional plating film of Example 2 was composed of the sample for the execution of the sample 2-1 to the sample for the execution of the sample 2-6. Each of the sample for analysis 2-1 to the sample for application 2-6 was formed on the surface of a copper plate to form an electroless nickel plating film having a thickness of 5 μm, and then a substitution type of a film thickness of 0.07 μm was formed on the surface of the electroless nickel plating film. Electroless gold plating film. Then, using the above-described reductive electroless gold plating solution, a regenerative electroless gold plating film is formed on the surface of the replacement electroless gold plating film in accordance with the conditions of each plating time. In addition, each of the sample for the execution of the sample 2-1 to the sample for the application 2-6 is the same as the sample for the execution of the sample 1A-1 to the sample for the application 1A-6, so that the conditions of the plating time at the time of forming the regenerative electroless gold plating film are different. .

[Comparative example] [Comparative Example 1]

In Comparative Example 1, a replacement electroless gold plating solution was used, and in the same manner as in Example 1, a copper plate was used as a substrate, and an electroless nickel plating film/electroless palladium plating film/electroless gold plating film was formed on the substrate. Electroplated film.

Adjustment of Displacement Type Electroless Gold Plating Solution: The composition of the substitution type electroless gold plating solution used in Comparative Example 1 is shown below. The plating conditions (pH, liquid temperature) and composition are also shown.

Liquid temperature 80 ° C

Preparation of Electroplated Film: The sample of the additional plating film of Comparative Example 1 was composed of the comparative sample group 1A to the comparative sample group 1D. The comparative sample group 1A to the comparative sample group 1D were respectively different in film thickness of the electroless palladium film.

The comparative sample group 1A was composed of the comparative sample 1A-1 to the comparative sample 1A-6, and each comparative sample was formed on the surface of the copper plate to form an electroless nickel plating film having a film thickness of 5 μm, and then the electroless nickel plating film was used. The surface of the nickel plating film was formed to form an electroless palladium film having a film thickness of 0.1 μm. Then, a replacement electroless gold plating film was formed on the surface of the electroless palladium plating film by using the above-described replacement type electroless gold plating solution in accordance with the conditions of each plating time. Specifically, the conditions of the plating time at the time of forming the comparative sample 1A-1 to the comparative sample 1A-6-based replacement type electroless gold plating film are 10 minutes, 20 minutes, 30 minutes, 40 minutes, 50 minutes, 60 minutes. A sample of an additional gold-plated film was obtained.

The sample group 1B for comparison was composed of the sample for comparison 1B-1 to the sample for comparison 1B-6, and the film thickness of the electroless palladium film was 0.2 μm, which was the same as that of the sample group 1A for comparison. Production. In addition, each of the comparative sample 1B-1 to the comparative sample 1B-6 is the same as the comparative sample 1A-1 to the comparative sample 1A-6, so that the conditions of the plating time at the time of formation of the replacement type electroless gold plating film are different. .

The comparative sample group 1C was composed of the comparative sample 1C-1 to the comparative sample 1C-6, and the sample was the same as the comparative sample group 1A except that the film thickness of the electroless palladium film was 0.4 μm. Production. In addition, each comparative sample 1C-1 to comparative sample 1C-6 is the same as the comparative sample. 1A-1 to Comparative Sample 1A-6, the conditions of the plating time at the time of formation of the replacement type electroless gold plating film were different.

The comparative sample group 1D was composed of the comparative sample 1D-1 to the comparative sample 1D-6, and the sample was the same as the comparative sample group 1A except that the film thickness of the electroless palladium film was 0.6 μm. Production. In addition, each of the comparative sample 1D-1 to the comparative sample 1D-6 is the same as the comparative sample 1A-1 to the comparative sample 1A-6, so that the conditions of the plating time at the time of formation of the replacement type electroless gold plating film are different. .

[Comparative Example 2]

In Comparative Example 2, a conventional reductive electroless gold plating solution was used, and in the same manner as in Example 2, a copper plate was used as a substrate, and an electroless nickel plating film/displacement type electroless gold plating film was formed on the substrate. Electroplated film composed of electroless gold plating film.

Adjustment of the conventional non-electroless gold plating solution: The composition of the reductive electroless gold plating solution used in Comparative Example 2 is shown below. The plating conditions (pH, liquid temperature) and composition are also shown.

Production of electroplated film: Comparative Example 2 is formed on the surface of a copper plate After forming an electroless nickel plating film having a film thickness of 5 μm, a substitution-type electroless gold plating film having a film thickness of 0.05 μm was formed on the surface of the electroless nickel plating film. Then, using the above-described reductive electroless gold plating solution, a rectifying type electroless gold plating film having a film thickness of 0.20 μm was formed on the surface of the replacement electroless gold plating film.

[Evaluation]

Next, Examples 1 and 2 of the gold plating film produced by using the reductive electroless gold plating solution of the present invention were evaluated for the deposition rate, the surface morphology, and the like. In the following, Comparative Example 1 of Example 1 and Example 2, and a gold-plated film produced by using a replacement electroless gold plating solution, and a gold-plated film produced by using a conventional reductive electroless gold plating solution were used as needed. , as a comparison, specifically described.

In the first embodiment of the present invention, the gold-plated film of the sample group 1A for execution (sample 1A-1 for execution) and sample 1A-6 for execution is shown in Fig. 1 . The relationship between the plating time and the thickness of the plating film. Similarly, Fig. 2 shows the relationship between the plating time and the plating thickness of the gold plating film of Example 2 (the sample for the execution of the sample 2-1 to the sample for the execution 2-6) using the reductive electroless gold plating solution of the present invention. Further, in Fig. 2, an electron micrograph (x 10,000) of the gold plating film of the sample for execution 2-2 obtained by the plating treatment time of 20 minutes was shown.

It can be confirmed from Fig. 1 that the gold plating film formed on the surface of the electroless palladium coating film using the above-described reductive electroless gold plating solution has no influence on the thickness of the formed gold plating film, and is at a rate of 0.15 μm/30 minutes. A gold-plated film is formed in a stable manner.

Can be confirmed by Figure 2: using the aforementioned regenerative electroless plating The rectifying type electroless gold plating film formed on the surface of the replacement electroless gold plating film by the gold liquid has no influence on the thickness of the formed gold plating film, and forms a gold plating film at a rate of 0.17 μm/30 minutes.

Effect of the thickness of the electroless palladium coating on the deposition rate of the gold plating film: Next, in the case of Example 1 and Comparative Example 1, the effect of the thickness of the electroless palladium film on the deposition rate of the gold plating film is affected. , to describe. FIG. 3 shows a sample group 1A for execution of a gold-plated film on the surface of an electroless palladium-plated film using a regenerative electroless gold plating solution (sample 1A-1 for execution - sample 1A-6 for execution) The relationship between the film thickness of the electroless palladium coating film and the deposition rate of the gold plating film in the sample group 1D (the sample for the implementation 1D-1 to the sample for the application 1D-6). In Fig. 3, a comparative sample group 1A (comparative sample 1A-1 to comparative sample 1A-6) in which a gold plating film is formed on the surface of an electroless palladium plating film using a replacement type electroless gold plating solution is shown. The relationship between the film thickness of the electroless palladium plating film and the deposition rate of the gold plating film of the sample group 1D for comparison (comparative sample 1D-1 to comparative sample 1D-6).

As is apparent from Fig. 3, the gold plating film formed by using the replacement type electroless gold plating solution of the comparative sample group 1A to the comparative sample group 1D is thicker than the palladium plating film which becomes the base metal, and the gold plating film is lowered. The speed of precipitation. On the other hand, it was confirmed that the gold plating film formed by using the reductive electroless gold plating solution of the sample group 1A for performing the sample group 1A to the sample group 1D for execution does not have a thickness of the palladium plating film to be the base metal, and is stable at a constant rate. A gold-plated film is formed.

Surface morphology of the gold-plated film: Next, observation of the gold-plated skin formed on the surface of the electroless palladium film using the reductive electroless gold plating solution of the present invention The surface morphology of the membrane. In Fig. 4, an electron micrograph (x 10000 and × 30000) of the surface of the gold plating film of the sample 1A-2 for performing the rectifying type electroless gold plating film in the film thickness of 0.1 μm in Example 1 is shown. Further, the surface form of the reductive electroless gold plating film formed on the surface of the replacement electroless gold plating film using the reductive electroless gold plating solution of the present invention was observed. In Fig. 5, an electron micrograph (x30000) of the surface of the gold plating film of the sample 2-2 for performing the rectifying type electroless gold plating film in the film thickness of 0.13 μm in Example 2 is shown. As a comparative example, the surface form of the reductive electroless gold plating film formed on the surface of the replacement electroless gold plating film using a conventional regenerative electroless gold plating solution was observed. Fig. 5 shows an electron micrograph (x30000) of the surface of the gold-plated film of Comparative Example 2 in which a reductive electroless gold plating film was formed with a film thickness of 0.13 μm.

It can be confirmed from Fig. 4 and Fig. 5 that not only the regenerative electroless gold plating solution of the present invention but also the conventional regenerative electroless gold plating solution is used to form an electroless gold plating film densely.

Surface morphology after peeling of the electroless gold plating film: In addition, observing the electroless gold plating film or the nickel plating film after peeling off the electroless gold plating film and the electroless palladium film by the plating films shown in FIG. 4 and FIG. Surface morphology. Fig. 6 shows an electron micrograph (x5000) of the surface of the nickel-plated film after the electroless gold plating film and the electroless palladium plating film were peeled off from the state of Fig. 4. Fig. 7 shows an electron micrograph (x3000) of the surface of the nickel-plated film after the electroless gold plating film was peeled off from the state of Fig. 5.

6 and 7, it is clearly shown that the examples and comparative examples formed using the regenerative electroless gold plating solution are not confirmed to be part of the nickel plating film. corrosion.

Cross-sectional morphology of the electroplated film: Next, an electroless nickel plating film/electroless palladium film of Example 1 in which a gold plating film was formed on the surface of the electroless palladium film using the reductive electroless gold plating solution of the present invention was observed/none. A section of an electroplated film of a layer structure of an electrolytic gold plating film. Fig. 8 shows a cross-sectional observation photograph (x30000) of the plating film of the sample 1A-6 for performing the rectifying type electroless gold plating film with a film thickness of 0.3 μm. It can be confirmed from Fig. 8 that the electroless gold plating film formed using the above-described reductive electroless gold plating solution is uniformly formed on the surface of the palladium plating film.

Selective precipitation of gold-plated film: Next, in Fig. 9, the same is shown in Example 1 in which the gold-plated film is formed on the surface of the electroless palladium film by using the reductive electroless gold plating solution of the present invention. An electron micrograph (x500) of each of the end portion and the central portion of the electroplated product of the electroplated film was formed under the same conditions as those of the sample 1A-6. It can be confirmed from Fig. 9 that an electroless gold plating film is uniformly formed in the end portion and the central portion of the electroplated product. Therefore, it can be said from the photograph of Fig. 9 that the selective precipitation property of the re-electroless gold plating liquid-based electroless gold plating film of the present invention is good.

Effect of Nickel Dissolution in Gold Plating Solution: Next, in the case of Example 1 in which a gold plating film is formed on the surface of an electroless palladium coating film using the reductive electroless gold plating solution of the present invention, dissolution of electroless nickel is performed for re Review the effect of the type of electroless gold plating solution. Specifically, the amount of elution of the base nickel to the electroless gold plating solution in the state where 1 g of gold was deposited on the surface of the electroless palladium film was measured by ICP. The comparative system was measured in the same manner as in the first embodiment except for Comparative Example 1 using a replacement electroless gold plating solution. In Figure 10, The elution amount of the electroless nickel of Example 1 using the regenerative electroless gold plating solution and the elution amount of the base nickel of Comparative Example 1 using the replacement electroless gold plating solution were shown. In Fig. 10, the values of the elution amount of Ni for the gold plating solution in the state where 1 g of gold is precipitated are measured using ICP.

As is apparent from Fig. 10, Comparative Example 1 in which a gold plating film per gram of gold was deposited by using a substitution type electroless gold plating solution was used as a base metal Ni in a replacement type electroless gold plating solution. On the other hand, Example 1 in which the gold-plated film per gram was deposited using the reductive electroless gold plating solution of the present application was used in the regenerative electroless gold plating solution, and only 0.2 ppm of Ni was used as the base metal.

From the result of the evaluation test, it can be said that the reductive electroless gold plating liquid of the present application can suppress the dissolution of the base nickel which has passed through the palladium plating film more remarkably than the state in which the gold plating film is formed, and the nickel can be prevented. Diffusion to the diffusion of the gold plating film.

Deviation in film thickness of the gold plating film: Next, the film thickness of the gold plating film formed by using the rectifying type electroless gold plating film on the surface of the replacement electroless gold plating film was examined. Here, as an example of using the regenerative electroless gold plating solution of the present invention, the film thickness of the regenerative electroless gold plating film was measured in the sample 2-2 for the second embodiment. As a comparative example, the film thickness of the reductive electroless gold plating film was measured using Comparative Example 2 of a conventional reductive electroless gold plating solution. Each of the results of the measurement of the film thickness at 20 points was shown in Table 1. In addition, in Fig. 11, a diagram showing the state of the deviation will be shown.

The average thickness of the electroless gold plating film of the sample 2-2 for the implementation of the regenerative electroless gold plating solution of the present invention is 0.199 μm, and the difference between the maximum value and the minimum value is remarkably small to 0.01 μm. It became significantly smaller and became 0.004. On the other hand, the average value of the film thickness of the electroless gold plating film of Comparative Example 2 using the conventional regenerative electroless gold plating solution was 0.206 μm, and the difference between the maximum value and the minimum value was 0.036 μm, and the standard deviation was 0.013. Therefore, it is known that the film thickness of the electroless gold plating film is covered by the use of the regenerative electroless gold plating liquid of the present invention, which is relatively high, by using the regenerative electroless gold plating liquid of the prior art. Level, to narrow the deviation and become uniform. From this result, it is understood that the use of the regenerative electroless gold plating solution of the present invention can achieve a more uniform plating treatment on the entire surface to be plated, thereby achieving an improvement in quality. Further, since the electroless gold plating film can be uniformly formed with a desired film thickness, formation of an electroless gold plating film exceeding a required film thickness can be suppressed, and the excess gold can be greatly reduced.

Wire-bonding characteristics of a gold-plated film: Next, a gold-plated film formed by using the regenerative electroless gold plating solution of the present invention Wire-bonding characteristics are used for review. Here, as an example of using the regenerative electroless gold plating solution of the present invention, the strength of the wire-bonding of the regenerative electroless gold plating film was measured in the sample 2-2 for the second embodiment. As a comparative example, the strength of wire-bonding of the regenerative electroless gold plating film was measured using Comparative Example 2 of a conventional regenerative electroless gold plating solution. Specifically, in the reflow type electroless plating film of the sample 2-2 and the comparative example 2, a gold wire having a wire diameter of 25 μm was bonded by a wire bonding apparatus, and the wire was pulled by a pull tester to measure wire bonding. (wire-bonding) strength. Twenty sites were measured, and the maximum, minimum, and average values of the wire-bonding strength were determined. The results of the measurement are shown in Fig. 12.

The maximum value of the wire-bonding strength of the electroless gold plating film of Example 2 (Example 2-2 for the implementation) using the regenerative electroless plating solution of the present invention is 6.0 gf, and the minimum value is 4.8 gf, and the average value is 4.8 gf. The value is 5.3 gf. Next, the maximum value of the wire-bonding strength of the electroless gold plating film of Comparative Example 2 using the conventional regenerative electroless plating solution was 6.0 gf, the minimum value was 4.8 gf, and the average value was 5.3 gf. From these results, it was found that the electroless gold plating film obtained by using the reductive electroless plating solution of the present invention has almost no difference from the state of using the conventional regenerative electroless plating solution, and good wire bonding is obtained. )strength. Therefore, according to the regenerative electroless gold plating solution of the present invention, it can be said that a gold plating film capable of achieving a high degree of wire-bonding bonding reliability can be provided.

[Industrial availability]

The reductive electroless gold plating liquid of the present invention can remarkably suppress the elution of a base metal such as nickel or palladium, and thicken the adhesion gold plating film on the surface of the base metal at a high deposition rate. Thus, if it is invented by the present invention, it is possible to provide a wire-bonding gold plating film having a high bonding reliability.

Claims (8)

A regenerative electroless gold plating solution is a regenerative electroless gold plating solution formed on an electroless gold plating film on a surface of a substrate to be coated, which is characterized by comprising a water-soluble gold compound, citric acid or citrate, and A bis-diaminetetraacetic acid or an ethylenediamine tetraacetate, a hexamethylenetetramine, and a chain polyamine having an alkyl group having 3 or more carbon atoms and 3 or more amine groups. For example, the regenerative electroless gold plating solution of the first aspect of the patent application has a pH of 7.0 to a pH of 9.0. The regenerative electroless gold plating solution according to claim 1 or 2, wherein the aforementioned chain polyamine is 3,3'-diamino-N-methyldipropylamine or N,N'-double ( 3-Aminopropyl) Ethyldiamine. The regenerative electroless gold plating solution according to any one of claims 1 to 3, which contains a ruthenium compound as a precipitation promoter. An electroless gold plating method, characterized in that an electroless gold plating film is formed on the surface of the object to be plated by using a reductive electroless gold plating solution according to any one of claims 1 to 4. An electroless gold plating method according to claim 5, wherein the surface of the object to be plated is any one of copper, palladium, gold or nickel. The electroless gold plating method according to claim 6, wherein the surface of the object to be plated includes an electroless palladium film formed on the surface of the electroless nickel plating film. An electroplated article characterized by electroless gold plating by an electroless gold plating method according to any one of claims 5 to 7. Reason.