JP2009057624A - Chemical polishing agent and metal plating method using copper or copper alloy treated before plating using the chemical polishing agent - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a chemical polishing agent of copper or copper alloy which forms a surface state of a required and sufficient level, without generation of unevenness or the like, as pretreatment of plating of the copper or the copper alloy to which metal plating is applied, and to provide a metal plating method using the copper or the copper alloy treated before plating using the chemical polishing agent, as a plated material. <P>SOLUTION: The chemical polishing agent to be used for pretreatment of plating of a surface of the copper or the copper alloy includes each component of ferric sulfate, sulfuric acid, a nonionic surface active agent, and a halogen ion, wherein a value of a ratio of contents of the sulfuric acid to contents of the ferric sulfate, [the contents of the sulfuric acid]/[the contents of the ferric sulfate] is 1 to 4. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a chemical polishing agent and a metal plating method using copper or a copper alloy pre-plated with the chemical polishing agent.

  Since copper and copper alloys are easy to process and have good electrical conductivity, they are frequently used for electrical or electronic wiring, mechanical relays, connector contacts, and the like. In order to maintain the reliability of connection, a solder plating film or a gold plating film is formed as a metal plating film that also serves as corrosion protection at connection terminals and contacts of these wirings. When a gold plating film is formed, a nickel plating layer is provided between the underlying copper or copper alloy and the gold plating film as a barrier for preventing diffusion of the copper or copper alloy base and the gold plating film. At this time, in order to reduce the amount of nickel to be plated and the amount of gold, a smooth surface is generally used.

  However, if the surface has a gloss like a mirror surface, a problem arises in the adhesion between the copper or copper alloy base and the nickel plating film, or between the nickel plating film and the gold plating film. For this reason, the surface of copper or a copper alloy is roughened or activated to prevent the occurrence of poor adhesion. The processing method includes a mechanical method and a chemical method. However, to improve the adhesion of the plating film in recent years, a chemical method is adopted that uses an active surface that is as flat as possible and improves the adhesion to the plating layer, rather than roughening by a physical method. In many cases, it is formed on the surface of the base metal. That is, as a means for ensuring the adhesion of the plating film to the base metal, it has been attempted to improve the adhesion of the plating film by obtaining a chemical adhesion force, instead of seeking the physical anchor effect.

  In addition, printed wiring boards that mainly use copper foil as a conductive material also have uses that are inserted into sockets and used like memory cards used in personal computers and the like. As described above, in a card-shaped product, a nickel plating film and a gold plating film are often formed on the insertion terminal portion. Furthermore, the surface of the wiring is also roughened for the purpose of improving the adhesion of the solder film formed on the wiring surface and the adhesion of a film such as an etching resist or a permanent resist. The roughening state required here is sufficient at a submicron to several micron level. Therefore, a chemical roughening method is mainly employed for this purpose as well as the above-described contacts and terminals.

  For example, in Patent Document 1, for the purpose of providing a microetching agent that can perform microetching that does not cause etching unevenness even if fine stains such as oily components are present on the copper surface, (a) iron sulfate ( III), (b) a microetching agent for copper and / or copper alloy comprising an aqueous solution containing sulfuric acid and (c) a nonionic surfactant, wherein the concentration of (a) is 1 to 40% by weight (A) The proportion of (b) is 5 to 50 parts by weight with respect to 100 parts by weight, the concentration of (c) is 0.01 to 10% by weight, and the halogen content is 0.01 to 20%. (D) 0.01 to 30% by weight of phosphoric acid, or (e) 0.01 to 30% by weight of carboxylic acid, or (d) 0.01 to 15% by weight of phosphoric acid and ( e) Contains 0.01 to 15% by weight of carboxylic acid Composition is disclosed.

  In this example of Patent Document 1, as the color change resistance, the copper surface after etching the copper-clad laminate is visually observed, and no discoloration is observed over the entire copper surface, or a part of the copper surface. Although a slight discoloration can be seen, there are disclosed those having no practical problem. Further, in this example, the etching unevenness is also observed by visually observing the etched copper surface, and there is no etching unevenness over the entire copper surface, or there is slight etching unevenness on a part of the copper surface. Although it is seen, it is disclosed that it is at a level where there is no practical problem.

JP 2001-181868 A

  However, the microetching agent for copper and copper alloy disclosed in Patent Document 1 described above forms an etching resist or solder resist on the surface of the underlying copper and copper alloy when manufacturing a printed wiring board. In order to perform well, it is used as a pretreatment of the surface of the underlying copper and copper alloy.

  Certainly, the micro-etching agent for copper and copper alloy disclosed in Patent Document 1 can etch the surface of copper or copper alloy and dissolve the metal component at a certain level. That is, the micro-etching agent for copper and copper alloy disclosed in Patent Document 1 can remove contamination such as oil and fat adhering to the surface for copper and copper alloy together with metal components dissolved by etching. There is a possibility that a base surface suitable for plating can be obtained.

  Therefore, the microetching agent for copper and copper alloy disclosed in Patent Document 1 is not intended for adjusting the base for plating, but has been used as a pretreatment agent for plating. As a result, when the microetching agent of Patent Document 1 is used for the treatment of copper or copper alloy as a plating base, it is impossible to perform a good pretreatment for plating, and the corrosion resistance of the formed plating film is inferior. It is. That is, from the description of the example of Patent Document 1, it is called a level where there is no problem in practical use although etching unevenness is slightly seen on a part of the surface of copper or copper alloy which is an object to be plated. This is a level that is confirmed visually. For example, the surface of the copper or copper alloy that has been pre-plated with the microetching agent for copper and copper alloy disclosed in Patent Document 1 has a fine uneven shape formed on the surface, or an extra oxide film is formed. In some cases, the gloss of the ground surface after the treatment tends to be lost, and it is difficult to obtain a flat and activated ground surface. When metal plating is performed on the base metal in such a state, the risk of uneven plating increases.

  Moreover, the microetching agent for copper and copper alloy disclosed in Patent Document 1 has a high erosion rate of copper and copper alloy, and tends to increase the amount of erosion on the surface of the object to be plated by microetching. The microetching agent for copper and copper alloy disclosed in Patent Document 1 is originally intended to improve the forming ability with an etching resist or a solder resist when a printed wiring board is manufactured. This is because the etching amount in this case is 0.1 μm to 5 μm in thickness, and the purpose is to form certain irregularities as the surface shape after etching. Thus, the microetching solution having a high etching rate is difficult to be used as a plating pretreatment agent for the purpose of forming a flat surface with few irregularities and an activated state. This is because the purpose of use is different.

  On the other hand, in various cases using copper or a copper alloy as a base metal, it can be said that the surface state required for improving the adhesion with them varies depending on what (layer) is provided on the surface. Strictly speaking, when forming a plating film on the base metal, melting a solder on the surface of the base metal to form a solder film, and forming a resist film on the surface of the base metal, respectively, it is required. It is considered that the surface condition of the groundwork is different.

  From the above, when copper or copper alloy is used as the base metal and a plating film is formed on the surface, plating with no unevenness can be formed, and the plating film has excellent adhesion and corrosion resistance. There has been a need for chemical abrasives used as pre-plating treatments for copper or copper alloys that can form an underlying surface that allows layer formation.

  Therefore, as a result of diligent research, the inventors of the present invention, as a result of chemical research, used a pre-plating treatment for copper or a copper alloy surface having the following component structure, and copper or pre-plated using the chemical polishing agent. The inventors have come up with a method for metal plating on the surface of copper or copper alloy using a copper alloy.

Chemical abrasive according to the present invention: The chemical abrasive according to the present invention is a chemical abrasive used for pre-plating of copper or a copper alloy surface, and is ferric sulfate, sulfuric acid, nonionic surfactant, halogen Each component of ions is included, and the ratio of the content of sulfuric acid to the content of ferric sulfate [the content of sulfuric acid] / [the content of ferric sulfate] is 1 to 4. It is characterized by that.

  The chemical abrasive preferably has a ferric sulfate content of 5 wt% to 10 wt%.

  The chemical abrasive preferably has a sulfuric acid content of 10 wt% to 20 wt%.

  The chemical abrasive preferably has a nonionic surfactant content of 0.1 wt% to 5 wt%.

  The chemical abrasive preferably has a halogen ion content of 0.1 wt% to 10 wt%.

The metal plating method to the copper or copper alloy surface which concerns on this invention: The metal plating method to the copper or copper alloy which concerns on this invention is the copper or copper which performed the plating pretreatment using the said chemical abrasive as a to-be-plated object A metal plating method on the surface of copper or copper alloy using an alloy, comprising the following steps A to C.

Process A: A degreasing process in which the surface of copper or copper alloy and a degreasing agent are brought into contact with each other to perform a degreasing treatment.
Step B: A plating pretreatment step of treating the surface by bringing the copper or copper alloy obtained in Step A into contact with the chemical abrasive.
Process C: A metal plating process for performing metal plating on the surface of the copper or copper alloy obtained in Process B.

  The chemical abrasive according to the present invention includes components of ferric sulfate, sulfuric acid, nonionic surfactant, and halogen ion, and a ratio of sulfuric acid content to ferric sulfate content [sulfuric acid. Content] / [content of ferric sulfate] is a chemical abrasive having a value of 1 to 4, and does not contain harmful substances or special chemical substances. Therefore, the wastewater treatment load can be reduced. And if the pre-plating process is performed on the copper or copper alloy object to be plated by using this chemical abrasive, a good gloss surface without unevenness can be obtained. Therefore, if this surface is plated, the plating layer is excellent in film thickness uniformity and can be subjected to dense metal plating. Thus, if the thickness of the metal plating film is uniform and dense, the plating appearance is good and functions as a protective film having no defects, so that the corrosion resistance of the plating film is improved. As a result, the durability of the plated product is improved. In addition, it becomes possible to set the lower limit of the management width of the plating thickness low, which also saves resources.

Form of chemical abrasive according to the present invention: The chemical abrasive according to the present invention is a chemical abrasive used for plating pretreatment on the surface of copper or copper alloy, ferric sulfate, sulfuric acid, nonionic surfactant, Each component of halogen ions is included, and the ratio of the content of sulfuric acid to the content of ferric sulfate [the content of sulfuric acid] / [the content of ferric sulfate] is 1 to 4. Since the chemical abrasive does not use harmful substances or special chemical substances, the content of each component can be adjusted using chemicals that are readily available in the market. And, if the copper or copper alloy of the object to be plated is brought into contact with a chemical abrasive containing the above components and pre-plated, it is suitable for improving the adhesion of the metal plating film on the surface. A smooth base surface. The roughened surface after this treatment is different from the roughened shape when general micro-etching is performed, and the surface is glossy and flat, and has an extra level that hinders the adhesion of the plating film. No oxide film exists.

  First, in the chemical abrasive, the ratio of the content of sulfuric acid to the content of ferric sulfate [the content of sulfuric acid] / [the content of ferric sulfate] is set to 1 to 4. . In the present invention, the surface of copper or copper alloy is pretreated to an optimum state using ferric ions and free sulfate ions. Therefore, if the value of [sulfuric acid content] / [ferric sulfate content] is less than 1, the amount of free sulfate ions is insufficient with respect to the oxidizing power of ferric ions. When the amount of free sulfate ions is insufficient and the dissolution of copper oxide is delayed, metallic copper and copper oxide coexist. When metallic copper and copper oxide coexist, the copper oxide tends to be a mixture of cupric oxide, which is easily soluble in sulfuric acid, and cuprous oxide, which is hardly soluble in sulfuric acid. As a result, uneven color occurs on the surface of the copper or copper alloy to be treated. That is, a value of [sulfuric acid content] / [ferric sulfate content] of 1 or more is effective in preventing color unevenness on the copper or copper alloy surface to be treated.

  On the other hand, even if the value of [Sulfuric acid content] / [Ferric sulfate content] exceeds 4, the ability of free sulfate ions to dissolve copper oxide is not improved, which is a waste of resources. . In addition, since the sulfuric acid concentration is high, the specific gravity and viscosity of the chemical polishing agent increase, and the power load required to circulate the chemical polishing liquid using a pump increases. Depending on the design of the process, the amount of sulfate ions brought into the next process increases, which increases the load of wastewater treatment, which is not preferable. Here, considering the more preferable amount of ferric sulfate content and the more preferable amount of sulfuric acid content described later, the more preferable range of the value of [sulfuric acid content] / [ferric sulfate content]. Is 1.37-2.83.

  And in the said chemical polishing agent, content of the said ferric sulfate is 5 wt%-10 wt%. However, in actual operation, a hepatic sulfate heptahydrate or a nonahydrate is used as a ferric sulfate source. Therefore, the content said here is displayed as content of only the ferric sulfate component which they contain. The ferric sulfate contained in the chemical polishing agent oxidizes the surface of copper or a copper alloy as ferric ions to convert metallic copper into copper oxide, and facilitates dissolution by free sulfate ions. However, when the content of ferric oxide is less than 5 wt%, the ability to oxidize the surface of copper or copper alloy is weak, uneven oxidation occurs on the surface of copper or copper alloy, or the desired surface state is obtained. This is not preferable because it is difficult to be formed. On the other hand, when the content of the ferric oxide exceeds 10 wt%, the surface of copper or a copper alloy shows a shape similar to that obtained when microetching is performed. When metal plating is performed on the copper or copper alloy surface, the gloss on the surface of the plating film is lost or unevenness in the gloss and color tone on the appearance tends to occur. From the above, in order to form an optimal surface state while maintaining an appropriate gloss on the copper or copper alloy surface, it is more preferable that the content of the ferric sulfate is 6 wt% to 8 wt%.

  In the chemical abrasive, the sulfuric acid content is preferably 10 wt% to 20 wt%. The free sulfate ions dissolve the copper oxide formed by the ferric ions oxidizing copper on the copper or copper alloy surface. Even if the content of sulfuric acid is less than 10 wt%, the chemical abrasive has the ability of free sulfate ions to dissolve copper oxide if it is immediately after the bathing. However, in the operation of continuously treating copper or a copper alloy, the time until the content of free sulfate ions contained in the chemical abrasive becomes insufficient in the ability to dissolve copper oxide is short. That is, it is not preferable because it is difficult to continue stable operation. On the other hand, even if the content of the sulfuric acid exceeds 20 wt%, as described above, the ability of free sulfate ions to dissolve copper oxide is not improved, and a negative effect due to the high sulfuric acid concentration is observed. Therefore, it is not preferable. Considering the above balance, the more preferable content of the sulfuric acid is 11 wt% to 17 wt%.

  Furthermore, in the chemical abrasive, the content of the nonionic surfactant is 0.1 wt% to 5 wt%. The nonionic surfactant has a function of desorbing oil and fat components adhering to the surface of copper or copper alloy. Therefore, if the content of the nonionic surfactant is less than 0.1 wt%, it is not preferable because the ability to desorb oil and fat components is insufficient. On the other hand, when the content of the nonionic surfactant exceeds 5 wt%, the nonionic surfactant tends to be adsorbed on the surface of copper or copper alloy, and as a result, uneven color on the copper or copper alloy surface appears. Since it occurs, it is not preferable. Therefore, from the viewpoint of eliminating the fat and oil component adhering to the copper or copper alloy surface and eliminating the adverse effects caused by adsorbing to the copper or copper alloy surface, the content of the nonionic surfactant is 0.5 wt% to 2%. More preferably, the content is 0.0 wt%.

  If the nonionic surfactant is water-soluble, it is not necessary to limit the chemical structure. For example, ester type nonionic surfactant and amide type nonionic surfactant and its alkylene oxide adduct, alkylene oxide adduct of fatty acid, alkylene oxide adduct of alcohol, alkylene oxide adduct of amines, polyalkylene Oxide etc. can be used. However, in order to exhibit the effect of the nonionic surfactant more stably, it is more preferable to use an ether type nonionic surfactant, and among them, polyoxyethylene lauryl ether and polyoxyethylene alkylamino ether are preferred. More preferably, is used.

  And in the said chemical polishing agent, content of the said halogen ion is 0.1 wt%-10 wt%. The halogen ion has a property of adsorbing on the surface of copper or a copper alloy. When copper or a copper alloy is brought into contact with the chemical abrasive, the halogen ions are adsorbed on the surface of the copper or copper alloy and the surface is homogenized, and the occurrence of uneven oxidation can be suppressed when copper is oxidized by ferric ions. The film thickness of the copper oxide on the underlying surface can be made uniform. However, if the halogen content is less than 0.1 wt%, the halogen ions cannot be uniformly adsorbed on the surface of the copper or copper alloy, and the surface of the copper or copper alloy cannot be homogenized. As a result, there is a tendency that uneven oxidation occurs on the surface of copper or copper alloy, which is not preferable. On the other hand, even when the halogen content exceeds 10 wt%, the homogenization effect on the surface of copper or copper alloy reaches saturation. Therefore, it is not preferable because the halogen tends to corrode surrounding facilities as well as wasteful use of resources.

  And as said halogen, it is preferable to use chlorine or a bromine. This is because stable adsorption is exhibited on the surface of copper or copper alloy. When chlorine is selected as the halogen, it can be prepared using hydrochloric acid because the chemical abrasive is an aqueous solution in the acidic region. Moreover, it can also prepare by substituting a part of ferric sulfate for a required quantity with ferric chloride.

Form of the metal plating method on the copper or copper alloy surface according to the present invention: The metal plating method on the copper or copper alloy surface according to the present invention was subjected to a plating pretreatment using the chemical abrasive as an object to be plated. A metal plating method using copper or a copper alloy, which includes the following steps A to C. Hereinafter, it demonstrates for every process.

Process A is a degreasing process in which the surface of copper or copper alloy is contacted with a degreasing agent to perform a degreasing process. In this process, the optimum method is selected from the method of immersing the copper or copper alloy that is the object to be plated in the prepared degreasing agent, the method of spraying the degreasing agent to the copper or copper alloy that is the object to be plated, etc. it can. Moreover, there is no special provision in the degreasing agent to be used. For example, if electrolytic degreasing is to be performed, electrolysis may be performed at 2.5 A / dm ² for 15 seconds using a cleaner 160, cleaner 160SW manufactured by Enson Co., Ltd., and the liquid temperature at 60 ° C. Moreover, a commercially available degreasing agent can be obtained and used after confirming that there is no influence on the appearance. The object to be plated after the degreasing treatment is washed with water.

  Process B is a plating pretreatment process in which the copper or copper alloy obtained in Process A is contacted with the chemical abrasive and processed. In this process, as in the case of the degreasing process, an optimum method is selected from a method of immersing copper or a copper alloy as an object to be plated in the chemical abrasive, a method of spraying the chemical abrasive on the copper or copper alloy, and the like. Can be implemented. If the dipping method is adopted, copper or a copper alloy is put in a rack or the like in a treatment tank in which the chemical abrasive is stored, and dipped for a predetermined time. At this time, when the chemical abrasive is circulated between the service tank and the treatment tank using a pump to remove foreign substances and the liquid is stirred at the same time, the surface of the copper or copper alloy is less likely to have gloss and uneven color tone. When the treatment for a predetermined time is completed, it is common and preferable that copper or a copper alloy is lifted from the treatment tank, washed with water, and conveyed to the next step.

  Step C is a metal plating step in which metal plating is performed on the surface of the copper or copper alloy obtained in step B. The metal plating method applied here is not particularly limited, and any one or both of an electroless plating method and an electroplating method can be used. At this time, although the copper or copper alloy has been washed with water, the surfactant or the like may be adsorbed and remain, which may adversely affect the plating process. In such a case, it is recommended that the object to be plated be pickled immediately before plating.

If the metal plating applied in step C is nickel plating and electroless nickel plating is applied, a catalyst such as palladium is applied, and then Melplate NI-6509MF manufactured by Meltex Co., Ltd. is used as the electroless nickel plating solution. If the liquid temperature is set to 80 ° C. to 92 ° C. and immersed for a predetermined time, an electroless nickel plating film can be obtained. If electro nickel plating is performed, an electro nickel plating film can be obtained by preparing a Watt bath or a sulfamic acid bath by itself and applying general plating conditions. If electroless gold plating is performed on the nickel plating film thus obtained, use Meltex AU-6630 manufactured by Meltex Co., Ltd. Thus, an electroless gold plating film can be obtained. When electrogold plating is performed, the liquid temperature is set to 40 ° C. to 60 ° C. and the cathode current density is 5 A / m ^{2 to} 40 A / m ² using Rohmell CS-100 manufactured by Rohm and Haas Electronic Materials Co., Ltd. If electrolysis is performed for a time, an electrogold plating film can be obtained.

  In Example 1, the ferric sulfate content was adjusted to 6.34%, the sulfuric acid content to 13.84%, the nonionic surfactant content to 0.85%, and the halogen content to 0.21%. The plating pretreatment was evaluated using the chemical abrasives. The value of [sulfuric acid content] / [ferric sulfate content] in this composition was 2.18. This composition is shown together with the composition of the microetching agent used in Comparative Example 1 in Table 1 below.

  Using the chemical abrasive, pure copper, brass, and phosphor bronze were used as pre-plating target materials and pre-treated at a liquid temperature of 45 ° C. for 15 seconds. And the quality of the pre-plating treatment state was evaluated by the glossiness of the target material surface after the pre-plating treatment. Glossiness is a target material that uses a digital gloss meter GH-26D manufactured by Murakami Color Research Laboratory Co., Ltd. as the gloss meter, the incident angle is set to 20 degrees, and the incident direction of the measuring light is pre-plated. The measurement was performed so as to coincide with the rolling direction. As a result, the glossiness of pure copper was 514.7, the glossiness of brass was 867.0, and the glossiness of phosphor bronze was 48.0, indicating good gloss. The evaluation results are shown in Table 2 later together with the evaluation results of Comparative Example 1.

In Example 2, phosphor bronze was used as an object to be plated, a plating material was prepared by the flow shown in FIG. 1, and the plating adhesion was evaluated. In the pre-plating treatment step shown in FIG. 1, the pre-plating treatment was performed on the object to be plated using the chemical abrasive. Thereafter, in the nickel plating step, a sulfamic acid bath prepared by adjusting nickel sulfamate tetrahydrate to 450 g / L, nickel chloride hexahydrate to 3 g / L, boric acid to 30 g / L, and pH to 4.8 is used. Then, the liquid temperature was set to 40 ° C., and electrolysis was performed at a cathode current density of 10 A / m ² for 2 minutes to form an electric nickel plating film having a thickness of 2 μm. Subsequently, in the gold plating step, Rohm and Haas Electronic Material Co., Ltd. Ronovel CS-100 was used, the liquid temperature was set to 50 ° C., and electrolysis was performed at a cathode current density of 5 A / m ² for 3 seconds to obtain a thickness of 0.05 μm. An electrogold plating film was formed. The plating thickness said here is the plating thickness when it is assumed that the surface of the object to be plated is an ideal flat surface without irregularities, and specifically, the two-dimensional area of the plating surface and the area range. It is the value converted from the weight change before and after plating. Further, this plating material was subjected to sealing treatment using a 2 vol% solution of Tetra Co., Ltd. Tetra C-2000.

  The plating adhesion of the plating material thus obtained was determined by the appearance after the salt spray was applied to the plating material. In salt spray, an aqueous solution at 35 ° C. with a sodium chloride concentration adjusted to 50 g / L was continuously sprayed for 96 hours, then washed with water and air-dried. The appearance of the plated material after spraying with salt water is shown in FIG. In FIG. 2, water droplets are visible on the surface of the plating material, but no lifting of the plating film or the like is observed, and there is no appearance that the phosphor bronze as the object to be plated is eroded by the salt water. From this result, it is understood that a plating film having good adhesion is formed on this plating material.

Comparative example

[Comparative Example 1]
In Comparative Example 1, the pretreatment property for plating was evaluated using the microetching agent disclosed in Example 1 of Patent Document 1 instead of the chemical abrasive used in the Examples. The composition of this microetching agent is shown in Table 1 below together with the composition of the chemical abrasive used in Example 1. The value of [sulfuric acid content] / [ferric sulfate content] in this composition was 0.25.

  And the plating pre-processing was implemented on the conditions similar to Example 1 except having used the said microetching agent. As a result, the glossiness of pure copper was 57.3, the glossiness of brass was 192.0, and the glossiness of phosphor bronze was 16.5. That is, the gloss of the surface of the target material is clearly lost by microetching. The evaluation results are shown in Table 2 below together with the evaluation results of Example 1.

[Comparative Example 2]
In Comparative Example 2, a plating material was prepared under the same conditions as in Example 2 except that the microetching agent disclosed in Example 1 of Patent Document 1 was used for the plating pretreatment. The plating adhesion was evaluated. The appearance of the plating material after spraying with salt water is shown in FIG. The plating film is floating on the surface of the plating material, and it is observed that the phosphor bronze, which is the object to be plated, is clearly eroded. Therefore, compared with the plating material obtained in Example 2, the adhesion of the plating film of the plating material obtained in Comparative Example 2 is clearly inferior.

[Contrast between Example and Comparative Example]
When the plating film obtained in Example 2 is compared with the plating film obtained in Comparative Example 2, the appearance of the plating film obtained in Example 2 is good and the adhesion to the object to be plated is also good. It is clear that it is stable. It is considered that the difference between Example 2 and Comparative Example 2 is caused by the surface state of the object to be plated before plating. When Example 1 is compared with Comparative Example 1, phosphor bronze having a gloss of 48 in Example 1 has a gloss of 16.5 in Comparative Example 1. That is, in Comparative Example 1, it is considered that the surface of phosphor bronze is micro-etched and has a large uneven shape. In other words, the three-dimensional surface area is increased, and it is also affected by the uneven shape, so that it can be inferred that there was an area where the coating with the plating film was insufficient even when electro nickel plating and electro gold plating were performed. Therefore, in the pretreatment of metal plating on copper or copper alloy, if the chemical polishing agent according to the present invention is used and the metal plating is performed in a state where the surface of the object to be plated is flat and gloss is good, plating with good adhesion is performed. A film is obtained.

  The chemical abrasive according to the present invention includes components of ferric sulfate, sulfuric acid, nonionic surfactant, and halogen ion, and a ratio of sulfuric acid content to ferric sulfate content [sulfuric acid. Content] / [content of ferric sulfate] is a chemical abrasive having a value of 1 to 4, and does not contain harmful substances or special chemical substances. Therefore, the wastewater treatment load can be reduced. And if the pre-plating process is performed on the copper or copper alloy object to be plated by using this chemical abrasive, a good gloss surface without unevenness can be obtained. Therefore, if this surface is plated, the plating layer is excellent in film thickness uniformity and can be subjected to dense metal plating. Thus, if the thickness of the metal plating film is uniform and dense, the plating appearance is good and functions as a protective film having no defects, so that the corrosion resistance of the plating film is improved. As a result, the durability of the plated product is improved. In addition, the lower limit of the management width of the plating thickness on the contact of the mechanical relay, the terminal portion of the printed wiring board, etc. can be set low, so that resources can be saved and the manufacturing cost can be reduced.

This is a nickel / gold plating process to be plated. 2 is a photograph showing the appearance of a plated material after spraying with salt water obtained in Example 2. FIG. 6 is a photograph showing the appearance of a plated material after spraying with salt water obtained in Comparative Example 2.

Claims (6)

A chemical abrasive used for pre-plating of copper or copper alloy surface,
Contains ferric sulfate, sulfuric acid, nonionic surfactant and halogen ion components, and ratio of sulfuric acid content to ferric sulfate content [sulfuric acid content] / [ferric sulfate] A chemical abrasive having a value of [iron content] of 1 to 4. The chemical abrasive according to claim 1, wherein the content of ferric sulfate is 5 wt% to 10 wt%. The chemical polishing agent according to claim 1 or 2, wherein a content of the sulfuric acid is 10 wt% to 20 wt%. The chemical abrasive according to any one of claims 1 to 3, wherein the content of the nonionic surfactant is 0.1 wt% to 5 wt%. The chemical abrasive according to any one of claims 1 to 4, wherein a content of the halogen ion is 0.1 wt% to 10 wt%. Metal plating on the surface of copper or copper alloy, characterized by using copper or copper alloy that has been subjected to plating pretreatment using the chemical abrasive according to any one of claims 1 to 5 as an object to be plated. A method,
A metal plating method comprising the following steps A to C:
Step A: A degreasing step in which the surface of copper or copper alloy is contacted with a degreasing agent to perform a degreasing treatment.
Step B: A plating pretreatment step in which the copper or copper alloy obtained in step A is contacted with a chemical abrasive and processed.
Process C: A metal plating process for performing metal plating on the surface of the copper or copper alloy obtained in Process B.