JP2009132967A - Acid degreasing agent used for pretreatment of electrolytic copper plating to surface of copper or copper alloy, and electrolytic copper plating method to surface of copper or copper alloy pretreated using the acid degreasing agent - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an acid degreasing agent which can remove fat and oil components remaining by a trace amount on the surface of copper or a copper alloy, and with which white irregularity, white specking or the like are not caused even when electrolytic copper plating is applied after direct plating treatment, and to provide an electrolytic copper plating method to the surface of copper or a copper alloy using the acid degreasing agent. <P>SOLUTION: The acid degreasing agent comprising the respective components of ferric sulfate, a cationic surfactant, and a nonionic surfactant is used for pretreatment of electrolytic copper plating to the surface of the copper or the copper alloy. Further, when the acid degreasing agent is used under the condition where concentration of halogen ions is ≤0.1 g/L in addition to the incorporation of the respective components, more preferable results can be obtained. In the degreasing treatment, the liquid temperature of the acid degreasing agent is controlled to 20 to 75°, this is brought into contact with the surface of copper or a copper alloy for ≥1 min, and the portion of the thickness of ≥0.01 μm on the surface of the copper or copper alloy is etched away. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an acidic degreasing agent used for pretreatment of electrolytic copper plating on the surface of copper or a copper alloy, and an electrolytic copper plating method for copper or copper alloy pretreated using the acidic degreasing agent.

  In a panel plating method and a pattern plating method, which are the main manufacturing methods of a printed wiring board (hereinafter referred to as “PWB”), a copper clad laminate (hereinafter referred to as “CCL”). The copper foil on the surface is plated with copper to ensure the necessary copper thickness as a conductor. In the case of double-sided printed wiring boards and multilayer printed wiring boards, this electrolytic copper plating is often applied for the purpose of plating in via (through) holes for establishing conduction between layers. In recent electronic devices, particularly mobile devices, an example of adopting a flexible printed wiring board (hereinafter referred to as “FPWB”) as one of means for achieving lightness, thinness and miniaturization is increasing. ing. In addition, a flexible copper clad laminate (hereinafter referred to as “FCCL”), which is a material for manufacturing FPWB, has a smooth surface and good bendability. A lot of foil is used.

  However, the above-mentioned FCCL often uses a polyimide resin film as an insulating resin base material. This polyimide resin has a property of swelling when contacted with a strong alkali. Moreover, it may be decomposed when it comes into contact with alkali at high temperature. Therefore, it is considered preferable to avoid alkali treatment for polyimide resin. Therefore, in the FPWB industry, an alternative technique for electroless copper plating that generally uses strong alkali has been sought as a pretreatment for imparting conductivity to inner walls such as through holes. Therefore, in the manufacturing process of FPWB, an example in which direct plating processing using palladium or graphite as a conductive film is increasing.

  And in the said patent document 1, it can roughen to the surface shape which has the deep unevenness | corrugation excellent in adhesiveness with a soldering resist etc. as a technique for pre-processing of the copper surface and a copper alloy surface, and also solder. In order to provide a microetching agent that can be brought into a surface state suitable for attachment, copper and copper alloy microetching agents comprising an aqueous solution containing a copper oxidizing agent, polyamine chains and / or cations A microetching agent containing a polymer compound having a functional group is disclosed.

Japanese Patent Laid-Open No. 9-41162

  In the general PWB manufacturing process including the copper plating process as described above, the surface of CCL, PWB or the like is subjected to pretreatment and then subjected to electrolytic copper plating. However, an appearance defect is often observed on the surface of the formed electrolytic copper plating film. And this appearance defect generally occurs due to variations in the composition of the plating solution used for electrolytic copper plating and variations in plating conditions, but it may also occur due to the influence of the base of the electrolytic copper plating. . In particular, when the rolled copper foil is used as a base for electrolytic copper plating, the appearance of the electrolytic copper-plated film tends to occur more easily than when the electrolytic copper foil is used as a base for electrolytic copper plating. The reason for this is that in the manufacturing process of surface-treated rolled copper foil, even if electrolytic degreasing, alkaline degreasing, pickling, etc. are performed, a small amount of rolling oil or copper oxide still exists on the surface of the product. It is mentioned. A similar phenomenon also appears on the surface of the FCCL that has been subjected to direct plating treatment. Therefore, when electrolytic copper plating is applied to the FCCL that has been subjected to direct plating treatment, degreasing treatment is performed with an acidic solution as a pretreatment. .

  By the way, the microetching agent disclosed in Patent Document 1 is an acidic solution, and in the PWB manufacturing process, an etching resist or a solder resist can be satisfactorily formed on the copper and copper alloy base, or the copper etching agent can be used. In addition, for the purpose of improving the adhesion between the copper alloy substrate and the base resin, the solution is used when forming microscopic irregularities by microetching the surface of the substrate.

  Moreover, although the microetching agent disclosed in Patent Document 1 is not a degreasing agent for ground treatment of electrolytic copper plating, if the surface of the copper foil subjected to direct plating treatment is processed using this microetching agent, There is a possibility that a degreasing effect can be obtained by dissolving and removing oxides adhering to the surface and removing surface contaminants such as oil and fat components together with metal components dissolved by etching. Therefore, a microetching agent was prepared with reference to the bath composition described in Patent Document 1 and used as a degreasing agent for the surface treatment of electrolytic copper plating on CCL. As a result, it became clear that it was difficult to obtain a good surface state after electrolytic copper plating, as is apparent from the later comparative examples.

  From the above, it is possible to remove a small amount of oil and fat components remaining on the surface of copper or copper alloy while being acidic, and even if electro copper plating is applied to the copper or copper alloy surface after direct plating treatment, There is a need for an acidic degreasing agent used for pretreatment of copper electroplating on copper or copper alloy surfaces where no white spots or the like occur, and a method for electroplating copper or copper alloy surfaces pretreated with the acidic degreasing agent. It was.

  Therefore, as a result of earnest research, the inventors of the present invention have found that the following is an acidic degreasing agent used for pretreatment of electrolytic copper plating on the copper or copper alloy surface, and the copper or copper alloy surface pretreated with the acidic degreasing agent. I came up with an electro copper plating method.

Acidic degreasing agent according to the present invention: The acidic degreasing agent according to the present invention is an acidic degreasing agent used for pretreatment of electrolytic copper plating on the surface of copper or a copper alloy, and is ferric sulfate, a cationic surfactant, and a nonion. It is characterized by containing each component of a surfactant.

  In the acidic degreasing agent according to the present invention, the halogen ion contained in the acidic degreasing agent preferably has a concentration of 0.1 g / L or less.

  In the acidic degreasing agent according to the present invention, the ferric sulfate contained in the acidic degreasing agent preferably has a concentration of 2 g / L to 500 g / L.

  In the acidic degreasing agent according to the present invention, the cationic surfactant contained in the acidic degreasing agent preferably has a concentration of 0.01 g / L to 10 g / L.

  In the acidic degreasing agent according to the present invention, the concentration of the nonionic surfactant contained in the acidic degreasing agent is preferably 0.05 g / L to 50 g / L.

Electro-copper plating method on the copper or copper alloy surface according to the present invention: The electro-copper plating method on the copper or copper alloy surface according to the present invention is applied to the copper or copper alloy surface pretreated with the acidic degreasing agent. An electrolytic copper plating method comprising the following steps A to C:

Step A: An acidic degreasing step in which the surface of copper or copper alloy is treated by contacting with the acidic degreasing agent.
Step B: An activation step for activating the copper or copper alloy surface obtained in Step A.
Step C: An electrolytic copper plating step in which the surface of the copper or copper alloy obtained in Step B is subjected to copper plating by an electrolytic method.

  In the method of electrolytic copper plating on the copper or copper alloy surface according to the present invention, the step A is performed by setting the liquid temperature of the acidic degreasing agent to 20 ° C. to 75 ° C., and this and the surface of the copper or copper alloy. It is also preferable to be an acidic degreasing step in which contact is made for at least minutes and the surface of the copper or copper alloy is removed by etching to a thickness of 0.01 μm or more.

  The acidic degreasing agent according to the present invention is an acidic degreasing agent used for pretreatment of electrolytic copper plating on the surface of copper or a copper alloy containing each component of ferric sulfate, a cationic surfactant, and a nonionic surfactant. Does not contain intentionally added halogen components. Therefore, if this acidic degreasing agent is used for the pretreatment of the copper or copper alloy surface to be subjected to electrolytic copper plating, an electrolytic copper plating film having a good surface without color unevenness can be formed on the surface of copper or copper alloy. . Moreover, even if it uses for the pre-processing of the base of the electro copper plating which performed the direct plating process on the copper or copper alloy surface, the electro copper plating film | membrane without generation | occurrence | production of a white nonuniformity, a white spot, etc. is obtained.

Form of acidic degreasing agent according to the present invention: The acidic degreasing agent according to the present invention is an acidic degreasing agent used for a pretreatment of electrolytic copper plating on the surface of copper or a copper alloy, and is ferric sulfate, a cationic surfactant. And each component of a nonionic surfactant. If this acidic degreasing agent is used, the oil or fat component or metal oxide on the surface of copper or copper alloy, which is the object to be plated, is removed, and a uniform copper or copper alloy surface is obtained without greatly changing the micro shape of the surface. I can do it. Hereinafter, each component contained in the acidic degreasing agent according to the present invention will be described.

  In the acidic degreasing agent according to the present invention, the halogen ion contained in the acidic degreasing agent has a concentration of 0.1 g / L or less. However, it is general to intentionally include halogen ions in an aqueous solution such as a pretreatment liquid or a plating liquid used for surface treatment of copper or copper alloy. For example, the microetching agent used in the examples disclosed in Patent Document 1 contains 0.5% to 1.4% of halogen ions. Thus, when copper or a copper alloy is immersed in an aqueous solution containing halogen ions, the halogen ions are mainly adsorbed on the crystal grain boundaries provided in the metal structure. And the effect which improves the uniformity of surface treatment and plating is exhibited. Therefore, in the Example of patent document 1, the micro-etching agent containing chlorine is used, the oxidation reaction of the copper or copper alloy surface is accelerated by spray treatment, and the uniform micro-etching treatment is performed on the copper or copper alloy surface. . That is, in the example of Patent Document 1, an electrolytic copper foil having small crystal grains is subjected to a microetching process, and the crystal grain boundaries on which halogen ions are adsorbed are preferentially removed by etching to remove the crystal grains. A microetched surface with good irregularities is formed.

  However, in this invention, the rolled copper foil with which FCCL is provided is also assumed as the to-be-plated object made into the process target. The rolled copper foil used for FCCL is enlarged due to recrystallization of crystal grains due to the thermal history in the manufacturing process of FCCL, and there are few crystal grain boundaries compared with electrolytic copper foil, but the grain size of crystal grains tends to vary greatly May occur. Therefore, in the case of a rolled copper foil having a recrystallized structure, if a pretreatment liquid having a high halogen ion concentration is used, the situation of peeling and dropping differs depending on the size of the crystal grains, and uneven gloss and uneven color on the plating base. Is likely to occur.

  Therefore, the concentration of the halogen ion in the acidic degreasing agent according to the present invention is kept as low as possible and maintained at 0.1 g / L or less. If the concentration of halogen ions in the acidic degreasing agent is 0.1 g / L or less, there are few crystal grain boundaries where halogen ions are adsorbed on the surface of copper or copper alloy, and the difference in crystal peeling due to the difference in crystal grain size. This is because becomes smaller. And this acid degreasing agent exhibits the effect which enables a crystal grain boundary and the inside of a crystal grain to be etched on the same level combined with the effect of the cationic surfactant mentioned later. However, in order to maintain the halogen ion concentration of the acidic degreasing agent at a level of 0.1 g / L or less, city water cannot be used for the preparation of the acidic degreasing agent. Therefore, the present invention is based on the use of water that does not contain halogen ions such as ion-exchanged water and pure water. In the present application, water that does not intentionally contain halogen ions is collectively referred to as “ion-exchanged water”.

  In the acidic degreasing agent according to the present invention, the ferric sulfate contained in the acidic degreasing agent has a concentration of 2 g / L to 500 g / L. In actual operation using an acidic degreasing agent, raw acid chemicals such as ferric sulfate heptahydrate and 9 hydrate procured on the market are dissolved in ion-exchanged water to prepare the acidic degreasing agent. Accordingly, the concentration of ferric sulfate referred to here is indicated as the concentration of only the ferric sulfate component contained in these raw chemicals. And the ferric ion which this acidic degreasing agent contains performs the function which oxidizes the surface of copper or a copper alloy, and makes it a copper oxide, and copper oxide melt | dissolves in an acidic degreasing agent. However, when the concentration of the ferric sulfate is less than 2 g / L, the ability to oxidize and dissolve the copper or copper alloy surface is weak, and it becomes difficult to remove the surface layer by etching uniformly. Cannot be demonstrated reliably. On the other hand, when the concentration of the ferric sulfate exceeds 500 g / L, it is difficult to dissolve the nonionic surfactant in the acidic degreasing agent, and the desired effect cannot be obtained. From the above viewpoint, in order to adjust the surface of copper or copper alloy to be electroplated to an optimum degreasing surface, the concentration of the ferric sulfate contained in the acidic degreasing agent is more preferably 10 g / L to 100 g / L. preferable.

  In the acidic degreasing agent according to the present invention, the concentration of the cationic surfactant contained in the acidic degreasing agent is 0.01 g / L to 10 g / L. In the acidic degreasing agent, the cationic surfactant is adsorbed on a metal component on the surface of the copper or copper alloy surface of the electrolytic copper plating. As a result, even if the rolled copper foil is a base for electrolytic copper plating, a uniform acidic degreasing treatment is possible. Cationic surfactants can be broadly classified into alkylamine salt types and quaternary ammonium salt types, and any one selected from general commercial products may be used. Use of a polyethyleneamine cationic surfactant or a polyallylamine cationic surfactant is more preferable because the effect of uniforming the acid degreasing treatment can be stably obtained.

  However, when the concentration of the cationic surfactant is less than 0.01 g / L, it becomes difficult to adsorb the cationic surfactant on the entire surface of the copper or copper alloy surface of the electrolytic copper plating. Then, not only is it difficult to obtain the effect of uniforming the acid degreasing treatment, but uneven gloss and color unevenness occur on the surface of copper or copper alloy, which is not preferable. On the other hand, even if the concentration of the cationic surfactant exceeds 10 g / L, the effect of uniforming the acidic degreasing treatment reaches saturation, resulting in wasted resources. Further, a phenomenon in which the cationic surfactant is adsorbed in a multilayer structure occurs on the surface of copper or copper alloy, and uneven gloss or color occurs on the surface of copper or copper alloy, which is not preferable. Therefore, a more preferable concentration varies depending on the type of the cationic surfactant used, but tends to be near the lower limit. For example, when a cationic surfactant mainly composed of polyethylene polyamine is used at a concentration of about 0.1 g / L, a stable degreasing treatment effect can be obtained even if other factors fluctuate.

  In the acidic degreasing agent according to the present invention, the nonionic surfactant contained in the acidic degreasing agent has a concentration of 0.05 g / L to 50 g / L. The nonionic surfactant swells and desorbs oil and fat components adhering to the surface of copper or copper alloy as the object to be plated. Nonionic surfactants include ester type, ether type, polyoxyethylene alkyl ether type, polyoxyethylene phenyl ether type, polyoxyethylene propylene glycol type, etc. Good. It is more preferable to use a polyoxyethylene alkyl ether-based nonionic surfactant or a polyoxyethylene polyoxypropylene glycol-based nonionic surfactant because the effect of the degreasing treatment can be stably obtained.

  However, if the concentration of the nonionic surfactant is less than 0.05 g / L, it is not preferable because the function of swelling and desorbing the fat component from the copper or copper alloy surface cannot be exhibited. On the other hand, when the concentration of the nonionic surfactant exceeds 50 g / L, the amount of the nonionic surfactant adsorbed on the copper or copper alloy surface tends to increase. As a result, color unevenness occurs on the copper or copper alloy surface, which is not preferable. Furthermore, from the viewpoint of swelling and desorbing the fat and oil component from the surface of copper or copper alloy and eliminating adverse effects such as adsorption on the surface of copper or copper alloy, the concentration of the nonionic surfactant is 0.5 g / L to 5 g / L is more preferable.

Form of electrolytic copper plating method on copper or copper alloy surface according to the present invention: The electrolytic copper plating method on the copper or copper alloy surface according to the present invention is a copper or copper alloy surface pretreated with the acidic degreasing agent. It is an electro copper plating method, and includes the following steps A to C. If this electrolytic copper plating method is used, it is possible to form a favorable electrolytic copper plating film with uniform thickness and no uneven brightness or color unevenness on the surface of copper or copper alloy. Hereinafter, explanation is added for each process.

  Process A is an acidic degreasing process in which the surface of copper or copper alloy is treated by contacting with the acidic degreasing agent. In this step, the liquid temperature of the acidic degreasing agent is set to 20 ° C. to 75 ° C., and this is brought into contact with the surface of the copper or copper alloy to be plated for 1 minute or more, and 0.01 μm on the surface of the copper or copper alloy. The above thickness is removed by etching. At this time, when the liquid temperature of the acidic degreasing agent to be used is lower than 20 ° C., a decrease in the ability to oxidize ferric sulfate copper and copper alloy is observed. And a cationic surfactant and a nonionic surfactant become easy to adsorb | suck to the copper or copper alloy surface. Furthermore, the nonionic surfactant is not preferable because the effect of swelling and desorbing the oil and fat component appears. On the other hand, when the liquid temperature of the acidic degreasing agent exceeds 75 ° C., the nonionic surfactant reaches a cloud point, and the ability to swell and desorb the oil and fat component provided in the nonionic surfactant is not preferable.

  And in an acidic degreasing process, this acidic degreasing agent and the surface of copper or a copper alloy are made to contact for 1 minute or more. In the method using the microetching agent disclosed in Patent Document 1, the metal on the copper or copper alloy surface is etched while being oxidized, and the crystal grain boundaries are preferentially etched away to drop the crystal grains. Therefore, in the embodiment, the liquid temperature of the microetching agent is set to 40 ° C., and the spray process for 60 seconds is employed. However, the acidic degreasing agent according to the present invention does not contain intentionally added halogen ions and acid components. As a result, the etching rate of the metal on the copper or copper alloy surface is slow, and the amount of etching on the copper or copper alloy surface is small even when acidic degreasing treatment is performed for a long time. Thus, if a copper or copper alloy surface and an acidic degreasing agent are contacted for a long time, a nonionic surfactant can swell and desorb an oil and fat component. Therefore, when the contact time is shorter than 1 minute, the fat and oil component does not swell sufficiently and a sufficient degreasing effect may not be obtained.

  In the step of bringing the acidic degreasing agent into contact with the copper or copper alloy surface, the most suitable method is a method of immersing copper or a copper alloy in the acidic degreasing agent, a method of spraying the acidic degreasing agent on the copper or copper alloy, or the like. What is necessary is just to select and implement a method. However, in order to stably obtain a good appearance without unevenness on the copper or copper alloy surface, an immersion method is preferable. Moreover, in order to acquire an effect in a short time when an immersion system is employ | adopted, the stirring of the acidic degreasing agent which immersed copper or the copper alloy is effective. A roll-to-roll process is possible as long as it is a process in which copper plating is applied to FCCL that has been subjected to direct plating after drilling, and a method of meandering while being immersed in various processing tanks can be adopted. Agitation at this time is obtained by circulating the acidic degreasing agent to the treatment layer and the running speed of the FCCL, but air bubbling or the like can also be used as an auxiliary. The method of spraying an acidic degreasing agent on the surface of copper or copper alloy may cause uneven gloss or uneven color on the surface of copper or copper alloy due to hydraulic pressure variation on the surface of copper or copper alloy. Caution must be taken. Since the oil and fat component released at this time is not dissolved in the acidic degreasing agent, the oil and fat component is separated and removed by providing a filter in the liquid circulation path.

  In the acidic degreasing step, the thickness of 0.01 μm or more of the surface of the copper or copper alloy surface is removed by etching as described above. The etching removal thickness referred to here is a thickness obtained by calculation from the weight difference before and after the acid or degreasing treatment of the copper or copper alloy surface of a certain area. That is, it is necessary to recognize that there is a certain variation in the local etching removal thickness. And this etching removal thickness becomes the parameter | index of the certainty of the degreasing effect with respect to the copper or copper alloy surface, and the suppression of the roughening of the surface. Therefore, if the etching removal thickness is less than 0.01 μm, even if it looks visually uniform, a portion where removal of fats and oils and the like is insufficient is localized. This is not preferable because the thickness may become uneven. However, the upper limit of the etching removal thickness is not particularly limited as long as the surface of the copper or copper alloy can be uniformly adjusted to a surface state that can be plated without uneven gloss or uneven color. However, when the etching removal thickness is excessive, roughening may proceed locally depending on the surface state of copper or copper alloy. When electrolytic copper plating is applied to such a surface, the roughened portion is emphasized, and a copper plating film having uneven gloss and uneven color is obtained. Also, when direct plating treatment is applied to the surface of copper or copper alloy, if the etching removal thickness becomes excessive, the conductor film and copper formed by direct plating treatment tend to fall off from the base together Appears. Therefore, from the above viewpoint, the etching removal thickness is more preferably set to 0.15 μm to 0.3 μm.

  Step B is an activation step for activating the copper or copper alloy surface obtained in step A. The surface of the copper or copper alloy that has been pickled and degreased in step A is in a state where the surfactant is adsorbed on the surface of the copper or copper alloy even after being washed with water, and the surfactant adsorbed on the surface of the copper or copper alloy. Also exhibits a rust-proofing effect. Therefore, when the copper or copper alloy surface is subjected to electrolytic copper plating in a state where the amount of adsorption of the surfactant is uneven, an electrolytic copper plating film with uneven brightness and uneven color is obtained. Therefore, pickling is performed immediately before the electrolytic copper plating is performed, and the adsorption state of the surfactant is adjusted so as not to affect the electrolytic copper plating, and the surface of the copper or copper alloy is activated. This operation is surface cleaning, and a sufficient activation effect can be obtained by immersion treatment for about 1 minute. The acid used here is not particularly limited, and a strong acid such as sulfuric acid, hydrochloric acid or nitric acid can be diluted. However, in order to activate the copper or copper alloy surface without oxidation, it is preferable to use about 10% dilute sulfuric acid as an activator. If dilute sulfuric acid is used, the adsorption state of the cationic surfactant adsorbed on the surface becomes more uniform, which can contribute to the improvement of uniform precipitation in electrolytic copper plating. This step may be performed by selecting an optimum method from a method of immersing copper or copper alloy in an adjusted activator, a method of spraying the activator on copper or copper alloy, or the like.

Process C is an electrolytic copper plating process in which the surface of the copper or copper alloy obtained in process B is subjected to copper plating by an electrolytic method. The electrolytic copper plating solution used here is not particularly limited. Even if it is prepared with a recommended bath composition using additives for a commercially available electrolytic copper plating solution in consideration of the characteristics of the copper film to be formed, It may be prepared. In the method using a commercially available additive for an electrolytic copper plating solution, Capper Gream ST-901, Capper Gream CLX, etc. manufactured by Rohm and Haas Electronic Materials Co., Ltd., which are also used in Examples described later, can be preferably used. . If it is a method prepared by itself, the sulfuric acid acidic copper plating solution is applied to a basic bath with a copper concentration of about 45 g / L to 60 g / L and a sulfuric acid concentration of about 50 g / L to 100 g / L as necessary. It can be prepared by adding an additive selected from disulfide, polyethylene glycol, Janus green and chlorine. And the liquid temperature of these electro-copper plating liquid shall be 25 to 45 degreeC, a phosphorus containing copper chip | tip or a dimension stability anode is used for an anode, copper or a copper alloy is made into a cathode, Cathode current density 0.5A / If electrolysis is performed at dm ^{2 to} 5 A / dm ² , an electrolytic copper plating film can be formed. In this process, if the copper or copper alloy has an independent shape, the rack is electroplated, and the strip copper or copper alloy is roll-to-roll. What is necessary is just to select and implement the method most suitable for the shape.

  In addition, in the concept of copper or copper alloy used in the specification of the present application, in general, those having a copper or copper alloy film, that is, a form in which a copper or copper alloy film is formed on the surface of a resin product or a metal not containing copper. Refrain from including.

Preparation of acidic degreasing agent: In Example 1, ferric sulfate 9 hydrate of reagent grade 1 was used as ferric sulfate. And what used the commercially available polyethylene polyamine as the main ingredient was used for the cationic surfactant (in the table | surface, it is only displayed as "polyethylene polyamine"). The nonionic surfactant used was a commercially available polyoxyethylene alkyl ether as a main ingredient (in the table, simply indicated as “polyoxyethylene alkyl ether”). An acidic degreasing agent was prepared using these agents. Specifically, first, the prescribed amounts of ferric sulfate, cationic surfactant, and nonionic surfactant were sequentially added while stirring about 0.7 L of ion-exchanged water in a 1.0 L beaker. And dissolved. Thereafter, ion exchange water is added to the solution to adjust the total liquid volume to 1.0 L, Fe ₂ (SO ₄ ) ₃ : 20 g / L, polyethylene polyamine: 0.1 g / L, polyoxyethylene alkyl ether : 1.0 g / L, Cl ⁻ : 0.01 g / L acidic degreasing agent was obtained. This bath composition is shown in Table 1 below together with the conventional degreasing agent used in Comparative Examples 1 to 4 and the bath composition of the microetching agent used in Comparative Examples 5 and 6.

Preparation of material to be plated: As a material to be plated for direct plating and electrolytic copper plating, 18 μm-thick rolled copper foil is laminated on both sides of a 25 μm polyimide film via a 20 μm adhesive layer. FCCL having a size of about 0.1 mm and a size of 250 mm × 300 mm was prepared.

Direct plating process: The direct plating process for the FCCL was performed by outsourcing the black hole process to an FCCL having a black hole processed conductor film. Table 2 below shows the flow of the steps from direct plating treatment to electrolytic copper plating performed in Examples 1 to 5 and Comparative Examples 1 to 6. The test conditions of Example 1 are shown in Table 3 below together with the test conditions of Examples 2 to 5 and Comparative Examples 1 to 6.

Acid degreasing: In the acid degreasing step, FCCL including the black hole-treated conductor film was cut into a size of 125 mm × 50 mm and used as a test piece. This test piece was immersed in 1.0 L of the acidic degreasing agent in a 1.0 L tall beaker at a liquid temperature of 40 ° C. for 3 minutes and subjected to acidic degreasing treatment, and then subjected to running water for 60 seconds. Washed with water. The copper etching removal thickness was determined from the mass difference of the CCL before and after the acidic degreasing treatment and found to be 0.3 μm.

Copper electroplating: In the copper electroplating process, sulfuric acid electrolytic copper plating using ion-exchanged water and containing 75 g / L of CuSO ₄ .5H ₂ O, 190 g / L of H ₂ SO ₄ and 0.05 g / L of chlorine ions. A bath was prepared and used as a basic bath commonly used in Examples and Comparative Examples. In Example 1, an electrolytic copper plating solution was prepared by adding 5 mL / L of Capper Gream ST-901 manufactured by Rohm and Haas Electronic Materials Co., Ltd. to the basic bath. Before the electrolytic copper plating step, as an activation step, the acid degreased FCCL was immersed in 10% sulfuric acid at room temperature for 1 minute for an acid activation treatment. In the electrolytic copper plating, 1.5 L of the prepared electrolytic copper plating solution was put into a water tank for a Haring cell having a capacity of 1.5 L, and electrolyzed at room temperature while blowing air and stirring. Specifically, phosphorous copper was used for the anode, and FCCL subjected to the acid activation treatment was used as a cathode, and electrolysis was performed at a cathode current density (DK) of 2 A / dm ² for 25 minutes. And FCCL which gave electrolytic copper plating was air-dried after washing, and produced electrolytic copper plating FCCL.

Appearance Evaluation: The appearance of the electrolytic copper plating FCCL was evaluated by visual appearance and gloss [GS (20 °)]. The glossiness [GS (20 °)] mentioned here is obtained by measuring the intensity of light bounced at a reflection angle of 20 ° by irradiating the surface of the subject with measurement light at an incident angle of 20 °. Was measured using GM-26D manufactured by Murakami Color Research Laboratory based on JIS Z 8741-1997. The visual appearance was good to the extent that white spots were scattered, and the glossiness [GS (20 °)] was 626.3. The evaluation results are shown in Table 4 later together with the evaluation results of Examples 2 to 5, and Comparative Examples 1 to 6.

  In Example 2, in place of the electrolytic copper plating solution used in Example 1, an electric power obtained by adding 5 mL / L each of Capper Gream CLX, A agent and C agent manufactured by Rohm and Haas Electronic Materials Co., Ltd. to the basic bath An electrolytic copper plating FCCL was prepared in the same manner as in Example 1 except that the copper plating solution was used. The etching removal thickness of copper in the acid degreasing treatment of Example 2 was 0.3 μm.

Appearance Evaluation: In the same manner as in Example 1, the appearance of the electrolytic copper plating FCCL was evaluated by visual appearance and glossiness [GS (20 °)]. The visual appearance was good to the extent that white spots were scattered, and the glossiness [GS (20 °)] was 399.2. The evaluation results are shown in Table 4 later together with the results of Example 1, Examples 3 to 5, and Comparative Examples 1 to 6.

  In Example 3, in place of the black hole process used in Example 1 for the direct plating process, an electrolytic copper plating FCCL was prepared in the same manner as in Example 1 except that the Crimson process was outsourced. . The etching removal thickness of copper in the acid degreasing treatment of Example 3 was 0.3 μm.

Appearance Evaluation: In the same manner as in Example 1, the appearance of the electrolytic copper plating FCCL was evaluated by visual appearance and glossiness [GS (20 °)]. The visual appearance was good to the extent that white spots were scattered, and the glossiness [GS (20 °)] was 610.6. The evaluation results are shown in the following Table 4 together with the evaluation results of Example 1, Example 2, Example 4, Example 5, and Comparative Examples 1 to 6.

  In Example 4, instead of the electrolytic copper plating solution used in Example 3 in the FCCL subjected to the acid degreasing treatment in the same manner as in Example 3, the basic bath was replaced with copper manufactured by Rohm & Haas Electronic Materials Co., Ltd. An electrolytic copper plating FCCL was prepared in the same manner as in Example 3 except that the electrolytic copper plating solution added with 5 mL / L of Gream CLX, agent A and agent C was used. The etching removal thickness of copper in the acid degreasing treatment of this Example 4 was 0.3 μm.

Appearance Evaluation: In the same manner as in Example 1, the appearance of the electrolytic copper plating FCCL was evaluated by visual appearance and glossiness [GS (20 °)]. The visual appearance was good to the extent that white spots were scattered, and the glossiness [GS (20 °)] was 632.8. The evaluation results are shown in Table 4 later together with the evaluation results of Examples 1 to 3, Example 5, and Comparative Examples 1 to 6.

  In Example 5, an electrolytic copper plating FCCL was prepared under the same conditions as in Example 3 except that the copper etching removal thickness in the acid degreasing treatment was set to 1.5 μm, and the visual appearance and glossiness [GS (20 ° ]] And evaluated. Therefore, in the process shown in Table 1, only the processing time of the degreasing process was changed to 15 minutes, and the electrolytic copper plating FCCL was created. The visual appearance was good to the extent that white spots were scattered, and the glossiness [GS (20 °)] was 576.7. The evaluation results are shown in Table 4 later together with the results of Examples 1 to 4 and Comparative Examples 1 to 6.

Comparative example

  In the comparative example, an acidic conventional degreasing agent that contains a nonionic surfactant and swells and desorbs fats and oils, and a microetching agent that contains chlorine ions and desorbs adhering fats and oils by etching copper are prepared. , Used in the degreasing step of Table 2.

Comparative Example 1 In Comparative Example 1, a sulfuric acid degreasing agent containing H ₂ SO ₄ : 25 mL / L and polyoxyethylene alkyl ether: 1 g / L was prepared as a conventional degreasing agent. The Cl ⁻ contained in this conventional degreasing agent was 0.01 g / L. The components included in the conventional degreasing agent are shown in Table 1 together with the bath composition of the acidic degreasing agent used in Examples 1 to 5 and the bath composition of the microetching agent used in Comparative Examples 5 and 6. . And the electrolytic copper plating FCCL was created like Example 1 except having replaced with the acidic degreasing agent used in Example 1, and having used the conventional degreasing agent in the degreasing process of Table 2. The etching removal thickness of copper in the degreasing treatment of Comparative Example 1 was 0.005 μm.

  Moreover, the external appearance of the electrolytic copper plating FCCL was evaluated in the same manner as in Example 1 in terms of visual appearance and gloss [GS (20 °)]. In the visual appearance, many white spots were observed, and the glossiness [GS (20 °)] was 212.7. The evaluation results are shown in Table 4 later together with the evaluation results of Examples 1 to 5 and Comparative Examples 2 to 6.

Comparative Example 2: In Comparative Example 2, an electrolytic copper plating FCCL was prepared in the same manner as in Example 2, except that the conventional degreasing agent was used in place of the acidic degreasing agent used in Example 2 in the degreasing step of Table 2. did. The etching removal thickness of copper in the degreasing treatment of Comparative Example 2 was 0.005 μm.

  Moreover, the external appearance of the electrolytic copper plating FCCL was evaluated in the same manner as in Example 1 in terms of visual appearance and gloss [GS (20 °)]. In the visual appearance, many white spots were observed, and the glossiness [GS (20 °)] was 85.4. The above evaluation results are shown in the following Table 4 together with the evaluation results of Examples 1 to 5 and Comparative Example 1 and Comparative Examples 3 to 6.

Comparative Example 3: In Comparative Example 3, an electrolytic copper plating FCCL was prepared in the same manner as in Example 3, except that the conventional degreasing agent was used in place of the acidic degreasing agent used in Example 3 in the degreasing step of Table 2. did. The thickness of copper removed by etching in the degreasing treatment of Comparative Example 3 was 0.005 μm.

  Moreover, the external appearance of the electrolytic copper plating FCCL was evaluated in the same manner as in Example 1 in terms of visual appearance and gloss [GS (20 °)]. In the visual appearance, white spots were observed on the entire surface, and the glossiness [GS (20 °)] was 191.5. The evaluation results are shown in Table 4 below together with the evaluation results of Examples 1 to 5, Comparative Example 1, Comparative Example 2, and Comparative Examples 4 to 6.

Comparative Example 4: In Comparative Example 4, an electrolytic copper plating FCCL was prepared in the same manner as in Example 4 except that the conventional degreasing agent was used in place of the acidic degreasing agent used in Example 4 in the degreasing step of Table 2. did. The etching removal thickness of copper in the degreasing treatment of Comparative Example 4 was 0.005 μm.

  Moreover, the external appearance of the electrolytic copper plating FCCL was evaluated in the same manner as in Example 1 in terms of visual appearance and gloss [GS (20 °)]. In the visual appearance, many white spots were observed, and the glossiness [GS (20 °)] was 254.8. The evaluation results are shown in Table 4 later together with the evaluation results of Examples 1 to 5 and Comparative Examples 1 to 3, Comparative Example 5 and Comparative Example 6.

Comparative Example 5: In Comparative Example 5, microetching with a bath composition of FeCl ₃ .2H ₂ O: 1% (5.06 g / L for Cl ⁻ ), formic acid: 5%, and epomin SP-200: 0.0002% An agent (microetching agent described in Example 2 of Patent Document 1) was prepared. The components contained in the microetching agent are shown in Table 1, together with the bath composition of the acidic degreasing agent used in Examples 1 to 5 and the bath composition of the conventional degreasing agent used in Comparative Examples 1 to 4. . And in the degreasing process of Table 2, it replaced with the acidic degreasing agent used in Example 3, and produced the electrolytic copper plating FCCL like Example 3 except having used the microetching agent. In the visual appearance of this electrolytic copper plating FCCL, white spots were observed on the entire surface, and the glossiness [GS (20 °)] was 42.6. The evaluation results are shown in Table 4 later together with the results of Examples 1 to 5 and Comparative Examples 1 to 4 and Comparative Example 6.

Comparative Example 6: In Comparative Example 6, the same degreasing process as in Comparative Example 5 except that the degreasing process of Table 2 was performed for 15 minutes so that the copper etching removal thickness in the degreasing process was 1.5 μm. An electrolytic copper plating FCCL was prepared. In the visual appearance of this electrolytic copper plating FCCL, many white spots were observed, and the glossiness [GS (20 °)] was 160.8. The evaluation results are shown in Table 4 below together with the results of Examples 1 to 5 and Comparative Examples 1 to 5.

Comparison between Examples and Comparative Examples: Prior to the comparison, it is confirmed that each electrolytic copper plating FCCL whose appearance was evaluated has a bright electrolytic copper plating film having a thickness of about 10 μm. However, as described above, the difference in surface condition after electrolytic copper plating caused by the difference in the type of degreasing agent used in the pretreatment and the etching removal thickness of copper is the difference in glossiness [GS (20 °)]. It clearly appears as a difference in visual appearance.

Comparison between Acid Degreasing Agent and Conventional Degreasing Agent: The glossiness [GS (20 °)] of Examples 1 to 4 using an acid degreasing agent has an average value of 545.4 and a standard deviation of 103.6 ( The coefficient of variation is 20.0%). On the other hand, the glossiness [GS (20 °)] of Comparative Examples 1 to 4 using a conventional degreasing agent has an average value of 186.1 and a standard deviation of 62.4 (variation coefficient 33.5%). is there. Therefore, even when both are acidic degreasing agents that do not contain halogen ions, when the acidic degreasing agent according to the present invention is used, the gloss is stronger and more uneven than when the conventional degreasing agent is used. An electro copper plating film having a small surface state is obtained.

  In addition, in the visual appearance, the copper electroplating FCCL pretreated with the acidic degreasing agent has only observed white spots to the extent that it is scattered, whereas the copper electroplating FCCL pretreated with the conventional degreasing agent has Vitiligo covering many to the entire surface is observed. Therefore, the difference in glossiness [GS (20 °)] between the example and the comparative example is also affected by the presence or absence of vitiligo.

  The etching removal thickness of copper in the case of degreasing the FCCL including the conductor film formed by the direct plating process is set to 0.3 μm in the degreasing process using the acidic degreasing agent of the above example. If the acidic degreasing agent is used in the degreasing treatment, the cationic surfactant is adsorbed on the surface of the metallic copper. Therefore, even when ferric ions oxidize the surface of the metal copper, unevenness is unlikely to occur, and the crystal grain boundaries and the exposed metal surface are etched almost uniformly by 0.3 μm. Moreover, even if the cation activator adsorb | sucks, the metal copper surface which performed the acid activation process using the dilute sulfuric acid after a degreasing process is uniform. As a result, the electrolytic copper plating FCCL in which electrolytic copper plating is performed on the surface of the FCCL that has been degreased using an acidic degreasing agent has a good appearance and gloss.

  On the other hand, when a conventional degreasing agent is used, the copper etching removal thickness is 0. 0 even though the treatment is performed with the same liquid temperature and treatment time when an acidic degreasing agent is used. 005 μm and very few. That is, in the conventional degreasing process using a degreasing agent, although the dissolution of copper oxide on the surface and the etching at the grain boundaries proceeded, the thickness of the copper removed by etching is low due to the low ability to dissolve metallic copper. It seems that there were few. However, since only the grain boundaries were etched and the surface was roughened, the gloss of the copper electroplating FCCL [GS (20 °) even if the surface subjected to the degreasing treatment with a conventional degreasing agent was subjected to the bright electrolytic copper plating. ] Does not reach the glossiness [GS (20 °)] level of electrolytic copper plating FCCL when an acidic degreasing agent is used.

  From the above, it is considered that the difference between the acidic degreasing agent according to the present invention and the conventional degreasing agent is the difference in the amount of copper removed by etching, particularly the ability to etch metallic copper. From this, it can be presumed that the etching performance of metallic copper is essential for the degreasing agent used in the degreasing treatment carried out as a pretreatment for the electro copper plating.

Contrast of acid degreasing agent and microetching agent: Glossiness [GS (20 °) of electrolytic copper plating FCCL obtained by using acid degreasing agent to change copper etching removal thickness to 0.3 μm and 1.5 μm )] Is compared between Example 3 and Example 5, the glossiness of the electrolytic copper plating FCCL of Example 5 is compared to the glossiness [GS (20 °)] 632.8 of the electrolytic copper plating FCCL of Example 3. The degree [GS (20 °)] is 576.7, which is about 9% lower. On the other hand, the glossiness [GS (20 °)] of the electro-copper plating FCCL obtained by using a micro-etching agent and changing the etching removal thickness of copper to 0.3 μm and 1.5 μm is shown in Comparative Example 5. When compared with Comparative Example 6, the glossiness [GS (20 °)] of the electrolytic copper plating FCCL obtained in Comparative Example 5 is 42.6, indicating a substantially matte state. However, in Comparative Example 6, the glossiness [GS (20 °)] of the electrolytic copper plating FCCL has recovered to 160.8.

  From the above phenomenon, in the degreasing process of Comparative Example 5, the etching of copper at the crystal grain boundaries where chlorine ions were adsorbed remarkably progressed, and the surface gloss of the surface of the copper electroplating FCCL was lost as compared with the conventional degreasing agent. It is thought that it became a shape. However, in the degreasing process of Comparative Example 6, since the etching removal thickness of copper was increased 5 times, the removal of crystal grains and the dissolution of metallic copper proceeded and the surface was homogenized. The glossiness [GS (20 °)] of the electrolytic copper plating FCCL is considered to have increased. However, since the absolute level of the glossiness [GS (20 °)] of the electrolytic copper plating FCCL is the same level or lower than those of Comparative Examples 1 to 4, a microetching agent is used for the pretreatment of the electrolytic copper plating. If used, etching of copper proceeds, but it is difficult to say that a surface state suitable for electrolytic copper plating is obtained.

  As is clear from the above comparison results, the acidic degreasing agent according to the present invention has the ability to etch the copper or copper alloy surface uniformly, smoothly and slowly. Therefore, even if the etching removal thickness of the copper or copper alloy surface varies during the degreasing process, the surface shape is not greatly affected. In addition, in order to obtain a uniform surface state, it is not necessary to etch the copper or copper alloy surface on the order of μm unlike a microetching agent. That is, if the acidic degreasing agent according to the present invention is used, it becomes possible to change the setting of the degreasing conditions corresponding to the state of the copper or copper alloy surface, even if the copper or copper alloy surface subjected to the degreasing treatment for a long time. Even if the copper electroplating is applied, white unevenness and white spots are hardly generated.

  The acidic degreasing agent according to the present invention is an acidic degreasing agent used for pretreatment of electrolytic copper plating on the surface of copper or copper alloy containing each component of ferric sulfate, cationic surfactant, and nonionic surfactant. Does not contain such ingredients. If this acidic degreasing agent is used for a degreasing treatment in performing electrolytic copper plating on the surface of copper or a copper alloy, a good electrolytic copper plating film free from uneven brightness and uneven color can be obtained. And the copper or copper alloy surface provided with the conductor film formed by the direct plating process can be subjected to electrolytic copper plating without generation of white unevenness or white spots. Therefore, even in the case of using a direct plating process to obtain continuity such as a through hole in a flexible printed wiring board using a rolled copper foil, white unevenness, white spots, etc. are present in the subsequent electrolytic copper plating. It does not occur, and a high-quality flexible printed wiring board can be obtained. Moreover, it is applicable also to the field | area of the decorative plating with the same external appearance request | requirement.

Claims (7)

An acidic degreasing agent used for pretreatment of electrolytic copper plating on the surface of copper or copper alloy,
An acidic degreasing agent comprising each component of ferric sulfate, a cationic surfactant, and a nonionic surfactant. The acidic degreasing agent according to claim 1, wherein the halogen ion contained in the acidic degreasing agent has a concentration of 0.1 g / L or less. The acidic degreasing agent according to claim 1 or 2, wherein the ferric sulfate contained in the acidic degreasing agent has a concentration of 2 g / L to 500 g / L. The acidic degreasing agent according to any one of claims 1 to 3, wherein the concentration of the cationic surfactant contained in the acidic degreasing agent is 0.01 g / L to 10 g / L. The acidic degreasing agent according to any one of claims 1 to 4, wherein the nonionic surfactant contained in the acidic degreasing agent has a concentration of 0.05 g / L to 50 g / L. A method for electrolytic copper plating on a copper or copper alloy surface using the acidic degreasing agent according to claim 1,
A method of electrolytic copper plating on a copper or copper alloy surface, comprising the following steps A to C.
Step A: An acidic degreasing step in which the surface of copper or copper alloy is treated by contacting with the acidic degreasing agent.
Step B: An activation step for activating the copper or copper alloy surface obtained in Step A.
Step C: An electrolytic copper plating step in which the surface of the copper or copper alloy obtained in Step B is subjected to copper plating by an electrolytic method. In the step A, the liquid temperature of the acidic degreasing agent is set to 20 ° C. to 75 ° C., and this is brought into contact with the surface of the copper or copper alloy for 1 minute or more, and 0.01 μm or more of the surface of the copper or copper alloy. The method for electroplating copper or copper alloy on the surface of copper or copper alloy according to claim 6, which is an acid degreasing step in which the thickness is removed by etching.