KR20160145533A - Reduction-type electroless gold plating solution and electroless gold plating method using said plating solution - Google Patents

Abstract

It is an object of the present invention to provide an electroless gold plating amount that does not contain harmful substances as well as realizes good wire bonding property by suppressing corrosion of a base metal. In order to attain this object, a reduction type electroless gold plating solution used for forming an electroless gold plating film by electroless plating on the surface of a cast material includes a water-soluble gold compound, citric acid or citrate and ethylenediaminetetraacetic acid or An electroless plating solution containing ethylenediaminetetraate, hexamethylenetetramine, an alkyl group having 3 or more carbon atoms and a chain polyamine containing 3 or more amino groups is employed.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an electroless gold plating method using a reduction type electroless gold plating amount and a plating solution using the plating solution,

The present invention relates to an electroless gold plating amount, an electroless gold plating method using the electroless gold plating amount, and a plating product plated by the electroless gold plating method. More specifically, the present invention relates to a reduction type electroless gold plating technique capable of performing a plating process directly on a surface to be coated.

In recent years, there has been an increasing demand for electronic devices to be made more sophisticated and multifunctional, while the printed circuit boards used in these electronic devices have become increasingly thin and thin. Circuit patterns have been made finer in order to cope with thin and light short-circuiting, and a high-level mounting technique has been demanded with the miniaturization of the circuit pattern. 2. Description of the Related Art Generally, in the field of printed wiring boards, a technique using solder or wire bonding is established as a technique for bonding mounting parts and terminal parts.

In order to secure the connection reliability of the bonding using the solder or the wire bonding, the plating treatment is performed as the surface treatment of the circuit mounting portion on the printed wiring board and the wiring pad as the terminal portion. The plating process is performed on a circuit pattern formed of copper or the like having a low electrical resistance, and there is a technique of sequentially performing nickel plating, palladium plating, and gold plating. The nickel plated film is to prevent erosion of the circuit by the solder, and the palladium plated film is to prevent the nickel constituting the nickel plated film from diffusing into the gold plated film. Then, the gold-plated film is formed in order to obtain wettability of a good solder while realizing a low electric resistance.

As a conventional technique of the above-described plating technique, there are, for example, the following Patent Documents 1 to 3. The electroless gold plating method described in Patent Document 1 is a method of forming a gold-plated film on nickel by an electroless gold plating solution containing a reducing agent and forming a gold plated gold film on nickel as a catalyst of electroless gold plating.

In the electroless gold plating method described in Patent Document 2, an electroless nickel plated film is formed by disposing a catalyst on a surface to be plated of an electronic component, an electroless palladium plated film is formed on the electroless nickel plated film, A method for forming an electroless gold plating film of a plated film laminate further comprising an electroless gold plating film on a palladium plating film, comprising the step of mixing a water-soluble gold compound, a complexing agent, formaldehyde and / or formaldehyde bisulfite adduct, An electroless gold plating film is formed by a first electroless gold plating process using an electroless gold plating bath containing a compound.

The reduced precipitation-type electroless gold plating solution for palladium coating described in Patent Document 3 is an electroless gold plating solution which enables a gold plating film to be formed directly on the palladium coating film, as an aqueous solution containing a water-soluble gold compound, a reducing agent and a complexing agent And contains at least one compound selected from the group consisting of formaldehyde sulfates, rongalite and hydrazines as a reducing agent.

Patent Document 1: JP-A-05-222541 Patent Document 2: JP-A-2008-266668 Patent Document 3: Japanese Patent Application Laid-Open No. 2008-174774

However, in the electroless gold plating method of Patent Document 1, since gold is deposited by depositing gold by using the oxidation-reduction potential difference of gold ions in the plating bath and the underlying nickel, There is a problem that nickel is diffused in the gold-plated film. When nickel is diffused in the gold-plated film, the gold-gold bonding strength of the wire bonding is deteriorated. In order to prevent such a problem, Patent Document 1 discloses that an electroless gold plating film is formed on a substituted gold plating film to increase the film thickness of gold, thereby suppressing a decrease in wire bonding property. However, since this technique requires the formation of a substituted gold-plated film, it raises costs and has a problem of poor productivity.

When the electroless gold plating method described in the above-mentioned Patent Document 2 or the reduction deposition type electroless plating metal deposit for the palladium coating described in Patent Document 3 is used, corrosion of nickel, which is a base metal, can be suppressed, It is difficult to secure the safety of the plating treatment operation because formaldehyde and formaldehyde sulfates adduct having high toxicity are contained in the plating solution.

Therefore, in the market, the demand for an electroless gold plating amount that does not contain harmful substances has increased, while suppressing the corrosion of the underlying metal to realize good wire bonding properties.

In order to solve the above-mentioned problems, the present inventors have made intensive studies and, as a result, have come up with the following electroless gold plating amount, electroless gold plating method and plating product.

The reduced electroless gold plating solution according to the present invention is used for forming an electroless gold plating film on the surface of the object to be plated, and is characterized in that a water-soluble gold compound, citric acid or citrate, ethylenediaminetetraacetic acid, A tetratrate, hexamethylenetetramine, an alkyl group having 3 or more carbon atoms, and a chain polyamine containing 3 or more amino groups.

The reduced electroless nickel plating solution according to the present invention preferably has a pH of 7.0 to pH 9.0.

In the reduced electroless gold plating solution according to the present invention, the chain polyamine is preferably 3,3'-diamino-N-methyldipropylamine or N, N'-bis (3-aminopropyl) ethylenediamine .

It is preferable that the reduced electroless nickel plating solution according to the present invention contains a thallium compound as a precipitating accelerator.

An electroless gold plating method according to the present invention is characterized in that an electroless gold plating film is formed on the surface of an object to be plated using the aforementioned reduced electroless plating gold deposit.

In the electroless gold plating method according to the present invention, it is preferable that copper, palladium, gold or nickel is present on the surface to be plated.

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

The plating product according to the present invention is characterized in that it is electroless gold plated by the electroless gold plating method described above.

The reduced electroless gold plating solution of the present invention comprises a water-soluble gold compound, citric acid or citrate, ethylenediaminetetraacetic acid or ethylenediaminetetraate, hexamethylenetetramine, an alkyl group having 3 or more carbon atoms and 3 or more amino groups It is easy to form a gold-plated film thick on the surface of the object to be plated.

Further, even when the nickel-plated film / palladium-plated film / gold-plated film provided at the electrical connection portion is formed by using the reduced electroless plating solution amount of the present invention, the film thickness of the gold- It is possible to rapidly form a coating on the surface of the palladium plating film. In addition, according to the reduced electroless plating gold deposit of the present invention, even when an electroless gold plating film is formed on the surface of the electroless palladium plating film formed on the surface of the electroless nickel plating film, as compared with the case of forming the replacement gold plating film The dissolution of nickel can be remarkably suppressed, and diffusion of nickel into the gold-plated film can be prevented. Therefore, according to the reduction electroless plating gold deposit of the present invention, it is possible to provide a gold plating film capable of realizing high bonding reliability of wire bonding.

Further, since the reduced electroless gold plating solution of the present invention does not contain formaldehyde or formaldehyde bisulfite adduct having high stability of the solution and high toxicity compared with the conventional electroless plating gold deposit, the safety of the plating process It becomes easy to secure.

In addition, the reduced electroless gold plating solution of the present invention does not cause gold precipitation reaction only on the surface of gold, palladium, nickel, copper, or the like, which can become the catalyst nucleus, . Therefore, it is possible to avoid the formation of the gold-plated coating on the portion where the precipitation of gold is not required, which is advantageous in that the raw material can be saved.

FIG. 1 is a graph showing the relationship between the plating time and the plating film thickness of the reduced electroless gold plating film of the working sample group 1A.
Fig. 2 is a graph showing the relationship between the plating time and the plating film thickness of the reduced electroless gold plating film of Example 2. Fig.
3 is a graph showing the relationship between the film thickness of the underlying palladium-plated film and the deposition rate of the gold-plated film when the electroless gold plating solution of Example 1 and Comparative Example 1 is used.
4 is an electron micrograph (x 10000 and x 30000) of the reduced electroless gold plating film of the working sample 1A-2.
Fig. 5 is an electron micrograph (x 30000) of the reducing electroless gold plating films of Practical Example 2-2 and Comparative Example 2. Fig.
6 is an electron micrograph (× 5000) of the surface of the nickel-plated coating film after peeling off the reduced electroless gold plating film and the electroless palladium plating film from the plating film of the working sample 1A-2.
Fig. 7 is an electron micrograph (x 3000) of the surface of the nickel-plated film after the reduction type electroless gold plating film was peeled from the plating films of Examples 2-2 and Comparative Example 2. Fig.
8 is a cross-sectional photograph (× 30000) of the reduced electroless gold plating film of the sample 1A-6.
Fig. 9 is an electron micrograph (x500) of an end portion and a central portion of a plated product in which a plated film is formed under the same conditions as the working sample 1A-6.
FIG. 10 is a graph showing the relationship of the amount of nickel eluted into the gold plating solution when the electroless gold plating amounts of Example 1 and Comparative Example 1 are used. FIG.
11 is a diagram showing the film thickness unevenness of the electroless gold-plated film of Example 2 and Comparative Example 2. Fig.
12 is a diagram showing the wire bonding characteristics of the electroless gold-plated film of Example 2 and Comparative Example 2. Fig.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of a reduced electroless plating amount of gold, a method of electroless plating using the plating solution and a plating product treated by the method according to the present invention will be described, respectively.

1. The reduction electroless gold plating amount

The reduced electroless gold plating solution according to the present invention is used for forming an electroless gold plating film on the surface of the object to be plated and includes a water-soluble gold compound, citric acid or citrate and ethylenediaminetetraacetic acid or ethylenediamine , 'Hexamethylenetetramine', a 'chain polyamine containing at least 3 carbon atoms and at least 3 amino groups'. Each component will be described below.

(1) Water-soluble gold compound

The water-soluble gold compound used in the reduced electroless gold plating solution according to the present invention may be any water-soluble gold compound such as a cyanide-based gold salt and a non-cyanide-based gold salt, provided that the plating solution is soluble in the plating solution and a predetermined concentration can be obtained. Specific examples of the water-soluble gold compound of the cyan-based gold salt include potassium cyanide, sodium cyanide, ammonium cyanide and the like. Specific examples of the water-soluble gold compound of the non-cyanide gold salt include a chloride salt, a sulfurous acid gold salt, and a thiosulfuric acid gold salt. Of these, gold potassium cyanide is particularly preferable. The water-soluble gold compounds may be used singly or in combination of two or more. On the other hand, the water-soluble gold compound is not limited to the gold compounds exemplified herein.

The concentration of the water-soluble gold compound in the reduced electroless gold plating solution according to the present invention is preferably 0.0025 mol / L to 0.0075 mol / L. If the concentration of the water-soluble gold compound is less than 0.0025 mol / L, the deposition rate of the gold-plated film is slow and it is difficult to obtain a gold-plated film having a desired film thickness. If the concentration is more than 0.0075 mol / L, the stability of the plating solution may decrease. It is disadvantageous.

(2) Citric acid or citrate

The reduced electroless gold plating solution according to the present invention contains citric acid or citrate. These citric acid or citrate salts are used as complexing agents capable of forming complexes with gold ions. The concentration of citric acid or citrate in the reducing electroless plating gold solution according to the present invention is preferably 0.05 mol / L to 0.15 mol / L. If the concentration of these citric acid or citrate salts used as a complexing agent is less than 0.05 mol / L, gold precipitates in the plating solution to degrade the solution stability. If the concentration exceeds 0.15 mol / L, complex formation proceeds excessively, It is difficult to obtain a gold-plated film having a desired film thickness because the speed is lowered.

(3) Ethylenediaminetetraacetic acid (EDTA) or ethylenediaminetartrate

The reduced electroless nickel plating solution according to the present invention contains ethylenediaminetetraacetic acid (EDTA) or ethylenediamine sodium salt. The ethylenediaminetetraacetic acid or ethylenediaminetetraacetate is a complexing agent used in combination with the aforementioned citric acid or citrate. The concentration of ethylenediaminetetraacetic acid or ethylenediaminetetraacetate in the reduced electroless nickel plating solution according to the present invention is preferably 0.03 mol / L to 0.1 mol / L. When the concentration of ethylenediaminetetraacetic acid or ethylenediaminetetraacetate used as a complexing agent is less than 0.03 mol / L, gold precipitates in the plating solution and the solution stability is inferior. When the concentration exceeds 0.1 mol / L, So that the precipitation rate of gold is reduced and it is difficult to obtain a gold-plated film having a desired film thickness.

(4) Hexamethylenetetramine

The reduced electroless nickel plating solution according to the present invention contains hexamethylenetetramine. The hexamethylenetetramine is used as a reducing agent for reducing gold ions in a plating solution to precipitate gold on the surface of the object to be plated.

The concentration of hexamethylenetetramine in the reduced electroless nickel plating solution according to the present invention is preferably 0.003 mol / L to 0.009 mol / L. If the concentration of hexamethylenetetramine is less than 0.003 mol / L, the deposition rate of the gold-plated film is slow and it is difficult to obtain a gold-plated film having a desired film thickness. When the concentration exceeds 0.009 mol / L, the reduction reaction proceeds rapidly, And thus the solution stability is poor and economically disadvantageous.

(5) Stain polyamine

The reduced electroless gold plating solution according to the present invention contains a chain polyamine containing an alkyl group having 3 or more carbon atoms and 3 or more amino groups. The chain polyamine is an amine compound which acts as a reducing aid for assisting the reduction of gold ions in the plating solution. Specific examples of the chain polyamine include 3,3'-diamino-N-methyldipropylamine and N, N'-bis (3-aminopropyl) ethylenediamine. This is particularly preferable from the viewpoint of the obtained plating film performance and economical efficiency.

The concentration of the chain polyamine in the reduced electroless plating metal solution according to the present invention is preferably 0.02 mol / L to 0.06 mol / L. When the concentration of the chain polyamine is in the range of 0.02 mol / L to 0.06 mol / L, it is possible to maintain a high deposition rate without affecting the film thickness of the base metal film. In addition, it is possible to improve the uniform throwing power of the gold-plated film and to make the gold-plated film to have a thickness of 0.2 μm or more. In addition, the solution stability can be remarkably increased.

(6) Other components

The amount of the reduced electroless plating solution according to the present invention includes the above-mentioned water-soluble gold compound, citric acid or citrate, ethylenediaminetetraacetic acid or ethylenediaminetetraate, hexamethylenetetramine, alkyl group having 3 or more carbon atoms and 3 In addition to the chain polyamine having an amino group, the precipitation accelerator may be contained. Examples of the precipitating accelerator used herein include a thallium compound and a lead compound. It is preferable to use a thallium compound from the viewpoint of thickening (thickening) of the obtained gold-plated film.

The concentration of the thallium compound as the precipitation accelerator in the reduced electroless plating metal solution according to the present invention is preferably 1 mg / L to 10 mg / L. If the concentration of the thallium compound as the precipitating accelerator is less than 1 mg / L, it becomes difficult to thicken the gold-plated film. When the concentration of the thallium compound as the precipitation accelerator exceeds 10 mg / L, further thickening can not be achieved, which is economically disadvantageous.

The reduced electroless nickel plating solution according to the present invention may contain additives such as a pH adjuster, an antioxidant, a surfactant, and a polishing agent in addition to the above-described essential components.

The pH adjusting agent is not particularly limited, and examples thereof include potassium hydroxide, sodium hydroxide, aqueous ammonia solution, sulfuric acid, and phosphoric acid. The reduced electroless nickel plating solution according to the present invention is preferably maintained at pH 7.0 to pH 9.0 by using a pH adjuster. If the pH of the reduced electroless plating solution is less than 7.0, the plating solution is liable to be decomposed. If the pH exceeds 9.0, the plating solution becomes too stable and the deposition rate of the plating becomes slow, which requires much time for thickening the gold plating film Because. Further, by adjusting the pH condition to 7.0 to 9.0, it becomes possible to perform a plating treatment of a plating object made of a material weak in alkali. Further, known additives such as an antioxidant, a surfactant, a polishing agent and the like can be used.

(7) Plating conditions

The conditions of the gold plating using the reduced electroless gold plating solution according to the present invention are not particularly limited, but the liquid temperature is preferably 40 캜 to 90 캜, and particularly preferably 75 캜 to 85 캜. The plating time is not particularly limited, but is preferably 1 minute to 2 hours, particularly preferably 2 minutes to 1 hour.

As described above, the reduction type electroless gold plating solution according to the present invention can be produced by mixing a water-soluble gold compound, citric acid or citrate, ethylenediaminetetraacetic acid or ethylenediaminetetratate, hexamethylenetetramine, And a chain polyamine containing three or more amino groups as essential components makes it easy to form a gold-plated film thick on the surface of the object to be plated by the electroless plating method.

Further, even in the case of forming a nickel-plated film / palladium-plated film / gold-plated film provided at the electric connection site, by using the reduced electroless plating film amount according to the present invention, the film thickness of the palladium- It is possible to quickly form the gold-plated film on the surface of the palladium-plated film. Even when the electroless gold plating film is formed on the surface of the electroless palladium plating film formed on the surface of the electroless nickel plating film, the case of forming the gold plating film by using the reduced electroless plating solution amount of the present invention The dissolution of nickel can be suppressed remarkably compared with the case of the present invention, and the diffusion of nickel into the gold-plated film can be prevented. Therefore, according to the reduced electroless plating gold deposit of the present invention, it becomes possible to provide a gold plating film capable of realizing high bonding reliability of wire bonding.

In addition, the reduced electroless gold plating solution of the present invention has a higher solution stability than the conventional electroless plating gold solution. For example, in the case of performing continuous plating while supplying a plating solution, MTO (metal turn over, in which gold in the plating solution is completely deposited in one turn) is used as an index of the deterioration of the plating solution. In the case of the conventional reduction type electroless plating gold deposit, the reduction electroless gold deposit amount of the present invention can realize the MTO of 5.0 turns or more, while the MTO is 2.0 to 3.0 turns.

In addition, since the reduced electroless gold plating solution of the present invention does not contain the highly toxic formaldehyde or formaldehyde bisulfite adduct contained in the conventional reduced electroless plating gold deposit, It becomes easy.

In addition, the reduced electroless nickel plating solution of the present invention has a precipitation reaction of gold only on the surface of gold, palladium, nickel, copper or the like that can become the catalyst nucleus and does not occur in the portion where there is no catalyst nucleus, Good. Therefore, it is advantageous in that it is possible to avoid the formation of a gold-plated coating on a portion where gold is not required to be deposited, thereby saving the raw material.

2. Electroless gold plating method

Next, an electroless gold plating method according to the present invention will be described. In the electroless gold plating method according to the present invention, electroless gold plating is performed on the surface of the object to be plated by using any one of the above-mentioned reduced electroless gold plating amounts to form a gold plating film. In the electroless gold plating method, the plating treatment is carried out by a method of immersing the object to be plated in the electroless gold plating amount in the same manner as the conventional treatment method of the electroless reduction electroless plating.

In the electroless gold plating method according to the present invention, it is preferable that copper, palladium, gold, and nickel are present on the surface of the object to be treated. The presence of copper, palladium, gold, or nickel on the surface of the casting may be present in any case. Particularly, it is more preferable that the object to be plated itself is constituted by copper, or a coating film made of copper, palladium, gold, nickel or an alloy containing these metals is used on the surface to be plated. For example, as the alloy containing these metals, gold cobalt can be mentioned. The alloy containing gold, palladium, nickel, copper, or these metals is an electroless gold-plated ground metal in the present invention, and these metals or alloys are hexamethylenetetra as the reducing agent contained in the above- And exhibits a catalytic activity on the nitrogen. It is particularly preferable to use an electroless palladium plating film, a replacement gold plating film, or a copper plating film as the film formed on the surface of the object to be plated. For example, in the case where electroless nickel plating is applied to the surface of the printed wiring board circuit or the terminal portion, it is preferable that an electroless palladium plating film is formed on the surface of the electroless nickel plating film. This is because a palladium-plated film is formed on the surface of the nickel-plated film, which is particularly effective in that diffusion of the nickel-plated film into the gold-plated film can be prevented.

3. Plating products

Next, a plating product according to the present invention will be described. The plating product according to the present invention is characterized in that the electroless gold plating process is performed on the surface of the object to be plated by the electroless gold plating method using any one of the electroless plating gold amounts described above. Among them, it is preferable that the surface of the object to be plated is subjected to electroless gold plating treatment using a reduced electroless plating gold amount of pH 7.0 to 9.0. In addition, as long as any one of copper, palladium, gold, and nickel is present on the surface of the object to be cast, the present form may be any case. Particularly, it is more preferable that the object to be coated is made of copper or a coating film made of copper, palladium, gold, nickel, or an alloy containing these metals on the surface of the object to be painted. Among them, the coating formed on the surface of the object to be cast is preferably an electroless palladium plating film, a replacement gold plating film or a copper plating film. Particularly, as a plating material having an electroless palladium plating film on its surface, it is preferable that an electroless nickel plating film is formed as a lower layer of the electroless palladium plating film. This is because the above-described plating process using the reduced electroless plating silver deposit can be particularly preferably used for forming the plating film at the electrically connected portion.

The embodiment of the present invention described above is an aspect of the present invention, and it goes without saying that it can be appropriately changed without departing from the gist of the present invention.

Hereinafter, Examples 1 and 2 of the gold-plated film produced using the reduced electroless gold plating solution of the present invention, Comparative Example 1 of the gold-plated film produced using the substitutional electroless plating gold alloy, Comparative Example 1 of the conventional reduced electroless plating solution The present invention will be described in more detail with reference to Comparative Example 2 of a gold-plated film produced by using the same. It is to be noted, however, that the present invention is not limited to the embodiments described below.

&Quot; Example 1 &

In Example 1, a reduced electroless plating gold deposit to which the present invention was applied was used, and a copper plate was used as a substrate, and a plating film composed of electroless nickel plating film / electroless palladium plating film / electroless gold plating film .

Adjustment of reduction type electroless gold plating amount: The composition of the reduction electroless plating gold amount used in this embodiment is shown below. Plating conditions (pH, liquid temperature) are shown together with composition.

Potassium cyanide 5 mmol / L

Dipotassium ethylenediaminetetate 0.03 mol / L

Citric acid 0.15 mol / L

Hexamethylenetetramine 3 mmol / L

3,3'-diamino-N-methyldipropylamine 0.02 mol / L

Thallium acetic acid 5 mg / L

pH 8.5

Liquid temperature 80 ° C

Preparation of a plated film: A sample having a plated film of Example 1 is composed of a working sample group 1A and a working sample group 1D. These practical sample groups 1A to 1D are distinguished by the difference in film thickness of the electroless palladium plating film.

The working sample group 1A is composed of the working samples 1A-1 to 1A-6, and each of the working samples is formed by forming an electroless nickel plating film having a thickness of 5 탆 on the surface of the copper plate and then subjecting the electroless nickel plating film An electroless palladium plating film having a thickness of 0.1 mu m was formed on the surface. Thereafter, a reduction type electroless gold plating film was formed on the surface of the electroless palladium plating film in accordance with each plating time condition using the above-described reduced electroless plating gold plating amount. Specifically, in the samples 1A-1 to 1A-6, the plating time was set to 10 minutes, 20 minutes, 30 minutes, 40 minutes, 50 minutes, and 60 minutes at the time of formation of the reduced electroless gold plating film, Lt; / RTI >

The working sample group 1B was composed of the working samples 1B-1 to 1B-6, and the film thickness of the electroless palladium plating film was 0.2 mu m. On the other hand, in each of the working samples 1B-1 to 1B-6, the plating time conditions at the time of forming the reduction type electroless gold plating film are different from those of the working samples 1A-1 to 1A-6.

The working sample group 1C was composed of the working samples 1C-1 to 1C-6, and was produced similarly to the working sample group 1A except that the thickness of the electroless palladium plating film was 0.4 mu m. On the other hand, in each of Practical Examples 1C-1 to 1C-6, the plating time conditions at the time of forming the reduction type electroless gold plating film are different from those of Practical Sample 1A-1 to Practical Sample 1A-6.

The working sample group 1D was composed of the working samples 1D-1 to 1D-6, and was produced in the same manner as the working sample group 1A except that the film thickness of the electroless palladium plating film was 0.6 mu m. On the other hand, in each of working samples 1D-1 to 1D-6, the plating time conditions at the time of forming the reduction type electroless gold plating film are different from those of the working samples 1A-1 to 1A-6.

&Quot; Example 2 "

In Example 2, the same reduction type electroless gold plating solution as in Example 1 was used, and a copper plate was used as a substrate, and an electroless nickel plating film / displacement type electroless gold plating film / reduction electroless gold plating film Thereby forming a plated film. A sample having a plated film as Example 2 is composed of Practical Samples 2-1 to 2-6. Each of Practical Examples 2-1 to 2-6 was obtained by forming an electroless nickel plated film having a thickness of 5 m on the surface of a copper plate and then forming a substitution type electroless nickel plating film having a thickness of 0.07 m on the surface of the electroless nickel plated film, A gold-plated coating film was formed. Thereafter, a reduction type electroless gold plating film was formed on the surface of the substitutional electroless gold plating film in accordance with each plating time condition using the aforementioned reduced electroless plating gold plating amount. On the other hand, in each of Practical Samples 2-1 to 2-6, the plating time conditions at the time of forming the reduction type electroless gold plating film are different from those of the Practical Examples 1A-1 to 1A-6.

&Quot; Comparative Example &

[Comparative Example 1]

In Comparative Example 1, a substitutional electroless gold plating solution was used and, as in Example 1, using a copper plate as a substrate, a plating film of electroless nickel plating film / electroless palladium plating film / electroless gold plating film .

Adjustment of substitution type electroless plating gold amount: The composition of substitution type electroless plating gold amount used in Comparative Example 1 is shown below. Plating conditions (pH, liquid temperature) are shown together with composition.

Potassium cyanide 10 mmol / L

0.03 mol / L of ethylenediaminetaphthalic acid

Citric acid 0.15 mol / L

Thallium acetate 50 mg / L

pH 4.5

Liquid temperature 80 ° C

Preparation of a plated film: A sample having a plated film of Comparative Example 1 is composed of a comparative sample group 1A to a comparative sample group 1D. These comparative sample groups 1A to 1D are distinguished by the difference in film thickness of the electroless palladium plating film.

The comparative sample group 1A is composed of the comparative samples 1A-1 to 1A-6. Each of the comparative samples was formed by forming an electroless nickel plated film having a thickness of 5 탆 on the surface of the copper plate, An electroless palladium plating film having a thickness of 0.1 mu m was formed on the surface. Subsequently, a substitutional electroless gold plating film was formed on the surface of the electroless palladium plating film according to each plating time condition, using the substitutional electroless plating amount described above. Specifically, the comparative samples 1A-1 to 1A-6 were prepared in such a manner that the plating time was set to 10 minutes, 20 minutes, 30 minutes, 40 minutes, 50 minutes, and 60 minutes at the time of forming the substitutional electroless gold plating film, Lt; / RTI >

The comparative sample group 1B was made of the comparative samples 1B-1 to 1B-6, and the film thickness of the electroless palladium plating film was 0.2 mu m. On the other hand, in each of the comparative samples 1B-1 to 1B-6, the plating time conditions at the time of forming the substitutional electroless gold plating film are different from those of the comparative samples 1A-1 to 1A-6.

The comparative sample group 1C was composed of the comparative samples 1C-1 to 1C-6, and the film thickness of the electroless palladium plating film was 0.4 mu m. On the other hand, in Comparative Samples 1C-1 to 1C-6, the plating time conditions at the time of forming the substitutional electroless gold plating film are different from those of Comparative Samples 1A-1 to 1A-6.

The comparative sample group 1D was composed of the comparative samples 1D-1 to 1D-6, and the film thickness of the electroless palladium plating film was 0.6 mu m. On the other hand, in each of the comparative samples 1D-1 to 1D-6, the plating time conditions at the time of forming the substitutional electroless gold plating film are different from those of the comparative samples 1A-1 to 1A-6.

[Comparative Example 2]

In Comparative Example 2, a conventional reduced electroless plating gold deposit was used, and in the same manner as in Example 2, using a copper plate as a substrate, an electroless nickel plating film / a substitutional electroless gold plating film / Thereby forming a plated film made of an electroless gold-plated film.

Adjustment of the conventional reduced electroless gold plating amount: The composition of the reduced electroless plating gold amount used in Comparative Example 2 is shown below. Plating conditions (pH, liquid temperature) are shown together with composition.

Potassium cyanide 0.015 mol / L

0.03 mol / L potassium cyanide

Sodium hydroxide 0.8 mol / L

Dimethylamine borane 0.2 mol / L

Lead compound 5 mg / L (based on lead)

pH 13

Solution temperature 70 ° C

Preparation of a plated film: In Comparative Example 2, an electroless nickel plated film having a thickness of 5 탆 was formed on the surface of a copper plate, and then a substitutional electroless gold plated film having a film thickness of 0.05 탆 was formed on the surface of the electroless nickel plated film . Thereafter, a reduction type electroless gold plating film having a film thickness of 0.20 탆 was formed on the surface of the substitutional electroless gold plating film by using the aforementioned reduced electroless plating amount.

[evaluation]

Next, the precipitation rate, surface morphology and the like of the gold plating film made using the reduced electroless plating gold deposit of the present invention were evaluated for Example 1 and Example 2. Hereinafter, the first and second embodiments of the present invention will be described in more detail with reference to Comparative Examples 1 and 2 of a gold plating film produced using a substitutional electroless gold plating solution or a gold plating film prepared using a conventional reduced electroless plating solution And will be described specifically.

Deposition rate: The relationship between the plating time of the gold-plated film of the sample group 1A (samples 1A-1 to 1A-6) and the plating film thickness was evaluated in the same manner as in Example 1 using the reduced electroless plating gold amount according to the present invention. 1. Similarly, FIG. 2 shows the relationship between the plating time and the plating film thickness of the gold-plated coating of Example 2 (Examples 2-1 to 2-6) using the reduced electroless plating gold deposit according to the present invention. On the other hand, FIG. 2 shows an electron micrograph (× 10, 000) of the gold-plated coating film of Practical Example 2-2 obtained by setting the plating treatment time to 20 minutes.

It can be seen from FIG. 1 that the gold plating film formed on the surface of the electroless palladium plating film using the above-described reduced electroless plating amount of gold is stable at a rate of 0.15 占 퐉 / 30 minutes without being influenced by the thickness of the gold plating film to be formed It was confirmed that a gold-plated film was formed.

It can be seen from Fig. 2 that the reduction type electroless gold plating film formed on the surface of the substitutional electroless gold plating film by using the reduction electroless plating gold amount described above is not affected by the thickness of the gold plating film to be formed, It was confirmed that a gold plating film was formed at a rate of 30 minutes.

Effect of electroless palladium plating film thickness on deposition rate of gold-plated film: Next, the effect of electroless palladium plating film thickness on the deposition rate of gold plating film is compared with Example 1 and Comparative Example 1. Fig. 3 shows the experimental sample groups 1A (samples 1A-1 to 1A-6) and samples 1D (sample samples 1C-1 to 1A-6) in which a gold-plated film was formed on the surface of the electroless palladium- 1D-1 to Example 1D-6) of the electroless palladium plating film and the deposition rate of the gold plating film. 3 shows a comparison sample group 1A (comparative samples 1A-1 to 1A-6) to a comparative sample group 1D (comparative samples 1A-1 to 1A-6) in which a gold- plated film is formed on the surface of an electroless palladium- The comparative sample 1D-1 to the comparative sample 1D-6) of the electroless palladium plating film and the deposition rate of the gold plating film.

It can be seen from FIG. 3 that the gold plating film formed by using the substitutional electroless gold plating amounts of the comparative sample group 1A to the comparative sample group 1D has a lower precipitation rate of the gold plating film as the underlying metal palladium plating film becomes thicker have. On the other hand, it was confirmed that the gold-plated film formed by using the reduced electroless plating silver plating solution of each of the working sample groups 1A to 1D was formed at a stable rate irrespective of the thickness of the palladium plating film as a base metal.

Surface morphology of the gold-plated film: Next, the surface morphology of the gold-plated film formed on the surface of the electroless palladium-plated film was observed using the reduced electroless gold plating solution of the present invention. Fig. 4 shows electron micrographs (x 10000 and x 30000) of the surface of the gold-plated coating film of the sample 1A-2 in which a reduction type electroless gold plating film was formed to a thickness of 0.1 탆 in Example 1. Fig. Further, the surface morphology of the reduced electroless gold plating film formed on the surface of the substitutional electroless gold plating film by using the reduced electroless plating amount of the present invention was observed. Fig. 5 shows an electron micrograph (x 30000) of the surface of the gold-plated film of Example 2-2 in which a reducing electroless gold plating film was formed to a thickness of 0.13 占 퐉 in Example 2. Fig. As a comparison, the surface morphology of the reduced electroless gold plating film formed on the surface of the substitutional electroless gold plating film by using the conventional reduced electroless plating gold deposit was observed. Fig. 5 shows an electron micrograph (x 30000) of the surface of the gold-plated film of Comparative Example 2 in which a reduced electroless gold plating film was formed to a thickness of 0.13 mu m.

4 and 5, it was confirmed that the electroless gold-plated film formed by using the reduced electroless gold plating solution as well as the reduced electroless plating gold alloy of the present invention was densely formed.

Surface morphology after electroless gold plating film peeling: The surface morphology of the electroless gold plating film or the electroless gold plating film and the electroless palladium plating film from the respective plating films shown in Figs. 4 and 5 Observed. 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. Fig. 7 shows an electron micrograph (x 3000) of the surface of the nickel-plated film after the electroless gold plating film was peeled from the state of Fig.

As is apparent from Figs. 6 and 7, none of the examples and comparative examples formed using the reduced electroless plating flux showed any local corrosion of the nickel plated film.

Electrolytic nickel plating film / electroless palladium plating film / electroless palladium plating film of Example 1 in which a gold plating film was formed on the surface of an electroless palladium plating film using the reduced electroless plating solution amount of the present invention The cross section of the plated film was observed in the layer structure of the plated-gold film. Fig. 8 shows a photograph (x 30000) of a cross-section of a plated coating film of a sample 1A-6 in which a reduced electroless gold plating film was formed to a thickness of 0.3 mu m. From FIG. 8, it was confirmed that the electroless gold-plated coating formed by using the reduced electroless plating gold deposit was uniformly formed on the surface of the palladium plating coating.

Electrolytic property of the gold-plated film: Next, using the reduced electroless plating solution amount of the present invention, a plating film was formed under the same conditions as the sample 1A-6 in Example 1 in which a gold-plated film was formed on the surface of the electroless palladium- Fig. 9 shows an electron micrograph (x500) of each of the end portion and the center portion of the formed plating product. 9, it can be confirmed that an electroless gold-plated film is uniformly formed at the end portion and the central portion of the plating product. From the picture of FIG. 9, therefore, it can be said that the electroless gold plating solution of the present invention has good electrowetability of the electroless gold plating film.

Effect of nickel elution in the gold plating solution: Next, Example 1, in which a gold plating film was formed on the surface of electroless palladium plating film using the reduced electroless plating gold deposit of the present invention, The effect of nickel dissolution was examined. Specifically, the elution amount of the base nickel in the electroless gold plating amount when 1 g of gold was deposited on the surface of the electroless palladium plating film was measured by ICP. As a comparison, Comparative Example 1 using a substitutional electroless gold plating amount was also measured in the same manner as in Example 1. Fig. 10 shows the elution amount of electroless nickel in Example 1 using a reduced electroless gold plating amount and the elution amount of ground nickel in Comparative Example 1 using a substitutional electroless plating gold amount. Fig. 10 shows a value obtained by measuring the elution amount of Ni into the gold plating amount when 1 g of gold was precipitated using ICP.

10, in Comparative Example 1 in which about 1 g of the gold plating film was deposited using the substitutional electroless plating gold deposit, Ni used as the base metal was eluted at 162 ppm in the substitutional electroless plating gold deposit. On the other hand, in Example 1 in which about 1 g of the gold plating film was deposited using the reduced electroless plating gold amount of the present application, only 0.2 ppm of Ni used as a base metal was eluted in the reduced electroless plating gold plating solution.

From the results of the evaluation test, it can be seen that the amount of the reduced electroless plating flux according to the present application can remarkably suppress the elution of the underlying nickel through the palladium plating film as compared with the case of forming the replacement gold plating film, It is possible to prevent diffusion of nickel.

Unevenness of Film Thickness of Gold-Plated Coating Film: Next, the unevenness of the film thickness of the gold-plated coating film formed on the surface of the substitutional type electroless gold plating film by using the reduced electroless plating amount of gold is examined. Here, as the embodiment using the reduced electroless plating gold deposit according to the present invention, the film thickness of the reduced electroless gold plating film was measured with respect to the embodiment sample 2-2 of the second embodiment. As a comparison, the film thickness of the reduced electroless gold plating film was measured for Comparative Example 2 using a conventional reduced electroless plating gold deposit. Table 1 shows the results of measuring the film thickness at 20 locations for each of the films. Fig. 11 shows a diagram showing an unbalanced state.

Example 2
(Practical sample 2-2) Comparative Example 2 Plating time 20 minutes 1.5 minutes

Film thickness

Average (탆) 0.199 0.206 Maximum value (탆) 0.204 0.218 Minimum (㎛) 0.194 0.182 Maximum-minimum (탆) 0.01 0.036 Standard Deviation 0.004 0.013

The film thickness average value of the electroless gold-plated film of Practical Example 2-2 using the reduced electroless gold plating solution according to the present invention was 0.199 mu m, the difference between the maximum value and the minimum value was 0.01 mu m, and the standard deviation was 0.004, which was remarkably small . On the other hand, the film thickness of the electroless gold plating film of Comparative Example 2 using the conventional reduced electroless plating solution was 0.206 mu m, the difference between the maximum value and the minimum value was 0.036 mu m, and the standard deviation was 0.013. Therefore, by using the reduced electroless plating gold deposit according to the present invention, the film thickness of the electroless gold plating film obtained is considerably high and the imbalance is small, as compared with the case of using the conventional reduced electroless plating gold deposit, It can be seen that it is uniform. From this result, by using the reduced electroless plating gold deposit according to the present invention, it is possible to more uniformly plated the entire surface to be plated, thereby improving the quality. Further, since an electroless gold-plated film can be uniformly formed with a desired film thickness, formation of an electroless gold-plated film exceeding a desired film thickness is suppressed, and excessive use of gold can be greatly reduced.

Wire Bonding Characteristics of Gold-Plated Coating Film Next, the wire bonding characteristics of the gold-plated coating formed by using the reduced electroless plating amount of gold according to the present invention will be examined. Here, the strength of the wire bonding of the reduced electroless gold-plated film was measured on the sample 2-2 of Example 2 as an example using the reduced electroless gold plating solution according to the present invention. As a comparison, the wire bonding strength of the reduced electroless gold-plated film was measured for Comparative Example 2 using the conventional reduced electroless gold plating solution. Specifically, gold wires of 25 mu m in diameter were bonded to the reduced electroless plating films of Practical Examples 2-2 and Comparative Example 2 with a wire bonding apparatus, and the wires were pulled with a pull tape to measure the strength of the wire bonding Respectively. And the maximum, minimum, and average values of the wire bonding strengths were obtained. The measurement results are shown in Fig.

The electroless gold-plated coating of Example 2 (Practical Example 2-2) using the reduced electroless plating solution according to the present invention had a maximum wire bonding strength of 6.0 gf, a minimum value of 4.8 gf and an average value of 5.3 gf. The electroless gold plating film of Comparative Example 2 using the conventional reduced electroless plating solution had a maximum wire bonding strength of 6.0 gf, a minimum value of 4.8 gf, and an average value of 5.3 gf. From these results, it was found that the electroless gold plating film obtained by using the reduced electroless plating solution according to the present invention can obtain a good wire bonding strength almost unchanged as in the case of using the conventional reduced electroless plating solution. Therefore, according to the reduced electroless plating gold deposit of the present invention, it becomes possible to provide a gold plating film capable of realizing the bonding reliability of high wire bonding.

&Quot; Industrial Availability "

The reduction type electroless plating metal deposit of the present invention can remarkably suppress the elution of the base metal such as nickel or palladium and can form the gold plating film on the surface of the base metal at a high deposition rate at a high deposition rate. Therefore, according to the present invention, it is possible to provide a gold-plated film having high bonding reliability of wire bonding.

Claims (8)

As a reduction type electroless gold plating amount used for forming an electroless gold plating film on a surface of a cast material,
A water-soluble gold compound, a citric acid or a citrate, an ethylenediaminetetraacetic acid or an ethylenediaminetetraacetate, hexamethylenetetramine, an alkyl group having 3 or more carbon atoms and a chain polyamine containing 3 or more amino groups Amount of reduced electroless gold. The method according to claim 1,
Reduced electroless gold plating amount of pH 7.0 to pH 9.0. 3. The method according to claim 1 or 2,
Wherein the chain polyamine is 3,3'-diamino-N-methyldipropylamine or N, N'-bis (3-aminopropyl) ethylenediamine. 4. The method according to any one of claims 1 to 3,
A reduced type electroless gold plating solution containing a thallium compound as a precipitating accelerator. A method for electroless gold plating, comprising the steps of: forming an electroless gold plating film on the surface of an object to be plated using the reduced electroless plating gold plating solution according to any one of claims 1 to 4. 6. The method of claim 5,
Wherein the surface of the object to be plated is one of copper, palladium, gold or nickel. The method according to claim 6,
Wherein the surface to be plated has an electroless palladium plating film formed on a surface of an electroless nickel plated film. An electroless gold plating process according to any one of claims 5 to 7, wherein the electroless gold plating process is performed.

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