TWI865507B - Copper surface processing equipment - Google Patents

Abstract

A copper surface processing device is used for processing the surface of an object having a surface covered with copper. The processing device comprises: a first tank for oxidizing the surface; and a second tank for electroplating the oxidized surface.

Description

Copper surface processing device

The present invention relates to a copper surface processing device.

Copper foil used for printed wiring boards requires good adhesion to resin. In order to improve this adhesion, there is a method of roughening the surface of copper foil by etching to improve physical adhesion. However, from the perspective of high density of printed wiring boards or transmission loss in high frequency bands, the surface of copper foil also needs to be flattened. In order to meet the above-mentioned opposite requirements, a copper surface treatment method that performs an oxidation step and a reduction step has been developed (see patent document 1). According to this method, the copper foil is pre-treated by immersing it in a solution containing an oxidizing agent to oxidize the surface of the copper foil to form copper oxide bumps, and then immersed in a solution containing a reducing agent to reduce the copper oxide, thereby adjusting the surface bumps to level the surface roughness. In addition, a method of adding interfacial active molecules in the oxidation step as a method of improving the adhesion of copper foil using redox treatment (see Patent Document 2), and a method of using aminothiazole compounds to form a protective film on the surface of copper foil after the reduction step (see Patent Document 3). In addition, a method has been developed in which a film having dispersed metal particles is formed by chemical plating on the surface of a copper oxide layer formed by roughening the surface of a copper conductor pattern on an insulating substrate (see Patent Document 4).

Generally speaking, metal oxides have a greater electrical resistance than unoxidized metals. For example, the electrical resistivity of pure copper is 1.7×10 ^-8 (Ωm), while the electrical resistivity of copper oxide is 1~10 (Ωm) and the electrical resistivity of cuprous oxide is 1×10 ⁶ ~1×10 ⁷ (Ωm). The electrical conductivity of copper oxide and cuprous oxide is worse than that of pure copper. Therefore, when oxidation treatment is used to roughen the surface of copper foil, the coating method does not use electroplating but chemical plating (see patent document 4). On the other hand, when copper particles are attached to copper foil by electroplating to roughen the surface of the copper foil, since there is no oxide on the surface of the copper foil, other metals can be plated on the roughened surface of the copper foil by performing electroplating again (Patent Documents 5 and 6).

The coating film is required to withstand use and environment, and have a degree of adhesion that does not cause practical obstacles. The known means include removing the oxide layer on the metal surface to strengthen the metal bond, and roughening the surface to disperse stress and ensure adhesion (Non-patent document 1).

Patent document 1 is International Publication No. WO2014/126193; Patent document 2 is Japanese Patent Publication No. 2013-534054; Patent document 3 is Japanese Patent Publication No. 8-97559; Patent document 4 is Japanese Patent Publication No. 2000-151096; Patent document 5 is Japanese Patent No. 5764700; Patent document 6 is Japanese Patent No. 4948579.

Non-patent document 1 is "Adhesion of coating film and its improvement method" written by Morikawa Tsutomu, Nakaide Takuo, and Yokoi Masayuki.

The purpose of the present invention is to provide a novel copper surface processing device.

Usually, when there is an oxide layer on the metal surface, electroplating is not performed directly due to reasons such as poor conductivity and difficulty in obtaining adhesion between the metal foil and the plated layer. Instead, the oxide is removed by acid treatment or the like before the electroplating is performed. This is because in general, it is known that the adhesion between the metal and the plated layer is ensured by metal bonding. If there is an oxide layer at the interface of the metal, it will hinder the metal bonding between the metal and the plated metal, making it difficult to obtain adhesion. In addition, if the metal is smooth, the stress is transferred to the interface between the metal and the plated metal and concentrated, and interface peeling is likely to occur. On the other hand, unlike a smooth surface, there is no clear surface for stress transmission at an uneven interface. When energy is transferred, it is believed that part of it causes the plated metal or the metal to deform, thereby consuming energy and improving adhesion. As a result of the inventor's research, the present invention has been used to make the oxide layer formed on the copper surface less than 400nm on average. The oxide layer surface is successfully coated with metal by electroplating, thereby minimizing the effects of poor electrical conductivity and metal bond obstruction. The fine concave and convex shapes can improve the adhesion between the metal and the plated metal by the anchor effect. In the past, there have been technologies and devices for oxidation treatment or reduction treatment, or electroplating treatment on the copper surface, but there is no technology for electroplating after oxidation treatment, and there is no processing device for it. In this way, the inventor has completed a novel copper surface processing device. One embodiment of the present invention is a copper surface processing device, which processes the surface of an object having a surface covered with copper, and the processing device has: a first tank for oxidizing the surface; and a second tank for electroplating the oxidized surface with a metal other than copper. The second tank may have an anode and a power source. A third tank may also be provided, and the third tank is used to alkaline-treat the surface with an alkaline aqueous solution before oxidizing the surface. A fourth tank and/or a fifth tank may also be provided, and the fourth tank is used to reduce the oxidized surface with a reducing agent after oxidizing the surface and before electroplating, and the fifth tank is used to dissolve the oxidized surface with a dissolving agent. The object may be a copper foil, copper particles, copper powder, or an object plated with copper.

1: Third slot

11: Scroll wheel

12: Squeeze roller

13: Guide roller

2: Sixth slot

3: The seventh slot

4: First slot

5: Fourth slot

6: Fifth slot

7: Second slot

8: Anode and power supply

100: Processing equipment

[Figure 1] A schematic diagram showing a first tank for oxidizing a surface and a second tank for electroplating the oxidized surface in one embodiment of the present invention.

[Figure 2] A schematic diagram of the overall processing device of one embodiment of the present invention.

[Figure 3] A schematic diagram of a conveying roller disposed between the grooves in one embodiment of the present invention.

[Figure 4] A schematic diagram of an extrusion roller provided on a conveying roller in one embodiment of the present invention.

[Figure 5] A schematic diagram of a guide roller provided on a transport roller in one embodiment of the present invention.

[Figure 6] A graph showing the relationship between the thickness of the oxide layer and the peeling strength in the embodiment and the comparative example.

[Figure 7] A graph showing the relationship between the thickness of the oxide layer and the heat-resistant degradation rate in the embodiment and the comparative example.

[Figure 8] A graph showing the relationship between the thickness of the oxide layer and the heat discoloration resistance ΔE*ab in the embodiments and comparative examples.

The following lists the implementation examples and describes the implementation forms of the present invention in detail. In addition, according to the description of this specification, those with ordinary knowledge in the technical field to which the invention belongs will understand the purpose, characteristics, advantages and concept of the present invention, and those with ordinary knowledge in the technical field to which the invention belongs can easily reproduce the present invention according to the description of this specification. The implementation forms and specific embodiments of the invention described below represent the preferred implementation forms of the present invention, which are used for illustration and explanation, and are not intended to limit the present invention. Those with ordinary knowledge in the technical field to which the invention belongs will understand that various modifications can be made based on the description of this specification within the intent and scope of the present invention disclosed in this specification.

Structure of a device for processing a copper surface: One embodiment of the present invention is a processing device (100) for processing the surface of an object having a surface covered with copper. The processing device has at least a first tank (4) and a second tank (7). The first tank (4) is used to oxidize the surface, and the second tank (7) is used to electroplating the oxidized surface. A third tank (1) can be arranged before the first tank (4). The third tank (1) is used to perform an alkaline treatment on the copper surface with an alkaline aqueous solution. In addition, a sixth tank (2) and a seventh tank (3) can be arranged next to the third tank (1). The sixth tank (2) is used to perform a cleaning treatment with an acid, and the seventh tank (3) is used to perform a weak alkaline treatment. And the fourth tank (5) and/or the fifth tank (6) can be set up between the first tank (4) and the second tank (7). The fourth tank (5) is used to reduce the oxidized copper surface with a reducing agent, and the fifth tank (6) is used to dissolve the oxidized copper surface with a solvent. One or more water washing tanks can be set between the tanks and/or at the beginning and end of the entire treatment. In addition, each tank is preferably equipped with a heating unit and a timer, by which the temperature or time of the treatment of each tank can be set. The function of each tank in the processing of the copper surface is explained below with reference to Figure 2. Figure 2 is a schematic diagram of the overall device in which all tanks except the water washing tank are equipped with one each and a roll-to-roll transport system is used. In addition, this device structure is an example, and any structure that can be revealed and understood by a person with ordinary knowledge in the technical field to which the invention belongs is included in the technical scope of the present invention. For example, Figure 2 sets one slot for each type of slot, but several slots can also be set for each type of slot.

Furthermore, in the case of continuous processing of copper components such as a roll-to-roll conveying system, the copper components are energized by the roller for electroplating. Other energizing positions are not limited to immediately before and after the second tank (7) for electroplating, and the rollers of other tanks may be energized.

In the third tank (1), the copper surface is subjected to an alkaline treatment using an alkaline aqueous solution. Therefore, the third tank (1) is made of a material that is resistant to the alkali used. The purpose of this alkaline treatment is degreasing.

In the sixth tank (2), the copper surface is cleaned with acid to remove the naturally oxidized film and reduce uneven processing. Therefore, the sixth tank (2) is made of a material that is resistant to the acid used.

In the seventh tank (3), in order to reduce uneven treatment and prevent the acid used for cleaning from mixing with the oxidant, a weak alkaline solution is used to perform alkaline treatment on the copper surface. Therefore, the seventh tank (3) is made of a material that is resistant to the alkali used.

The oxidation treatment in the first tank (4) is to use an alkaline solution containing an oxidant to oxidize the copper surface and form an oxide on the copper surface. Therefore, the first tank (4) is made of a material that is resistant to the oxidant and alkali used. The first tank (4) can have an operation mode of oxidizing only a portion of the surface of the copper component. For example, the copper component can be transported horizontally relative to the solution surface so that the non-treated surface does not contact the liquid. Alternatively, a liquid retaining component (such as a sponge) can be arranged in the first tank (4), which can contain an alkaline solution containing an oxidant, so that the copper component will not be directly immersed in the solution, and only a portion of the surface of the copper component will contact the liquid retaining component for oxidation treatment.

In the fourth tank (5), an alkaline solution containing a reducing agent is used to reduce the oxidized copper surface. This is to reduce the copper oxide formed on the copper foil to adjust the number and length of the bumps. For this purpose, the fourth tank (5) is made of a material that is resistant to the reducing agent and alkali used.

The fifth tank (6) is subjected to a dissolution treatment to dissolve the oxidized copper surface with a solvent. To this end, the fifth tank (6) is made of a material that is resistant to the solvent used. The purpose of the dissolution treatment is to adjust the protrusions on the oxidized copper surface.

In the second tank (7), the copper surface is electroplated with a metal other than copper. The second tank (7) is equipped with an anode and a power source for electrolysis. The type of anode is not particularly limited, and an insoluble anode such as a lead plate, a precious metal oxide film titanium, etc. can be used, or a soluble anode that dissolves and electrolyzes into a copper foil, etc. can be used.

The water in the washing tank can be heated to the same or similar temperature as the tanks before and after it, thereby preventing wrinkles that are easily caused by thermal expansion differences.

The solution used in the tanks other than the second tank (7) can be contained in the tank to immerse the copper surface, or can be sprayed onto the copper surface by a spray device installed in the tank. When the solution is contained in the tank, it is better to install a liquid circulation device in the tank. In this way, the uneven treatment caused by the solution can be reduced.

In FIG. 2, it is envisioned that the copper surface of copper foil, etc. is processed, and the copper foil is transported between the slots using a roll-to-roll transport system. FIG. 3 is an enlarged view of the roller (11). The transport conditions in this case are not particularly limited. For example, the linear speed of the copper foil can be 50~3000m/hr, and the tension of the copper foil can be 1~130kgf/m. In this system, an extrusion roller (12) as shown in FIG. 4 can be provided. In this way, liquid can be squeezed from the copper foil to reduce the liquid being carried into the next slot. In addition, a guide roller (13) as shown in FIG. 5 can be provided. In this way, longitudinal wrinkles can be prevented from occurring or the copper foil can be prevented from breaking.

The transportation of the copper-surfaced objects between the tanks is not limited to the roll-to-roll transportation system, and can be done manually or by a conveyor system such as a conveyor belt. In addition, a drying device can be provided to dry the copper surface after all steps are completed. The drying temperature is not particularly limited, and it is preferred to dry the copper surface at room temperature to about 230°C.

Copper surface processing method: The following describes a method for processing the copper surface using the above processing device. Here, in order to process only the portion that needs to be processed, only the portion can be processed by immersing only the portion in each liquid. In addition, in order to perform electroplating treatment on only one side of copper foil, etc., a known method (Japanese Patent Publication No. 2010-236037, Japanese Patent Publication No. 2004-232063) can be used.

First, in the third tank (1), the copper surface is treated with an alkaline aqueous solution. The method of alkaline treatment is not particularly limited. Preferably, a 30-50 g/L alkaline aqueous solution can be used, and a 40 g/L alkaline aqueous solution can be used. The alkaline aqueous solution, such as a sodium hydroxide aqueous solution, is treated at 30-50°C for 0.5-2 minutes. It is then preferred to wash the copper surface with water.

Next, the copper surface treated with alkaline can be cleaned with acid in the sixth tank (2). For example, the copper surface can be treated by immersing it in 5-20 wt% sulfuric acid at a liquid temperature of 20-50°C for 1-5 minutes. It is best to then wash the copper surface with water.

Afterwards, the copper surface can be treated with weak alkali in the seventh tank (3). The weak alkali treatment method is not particularly limited. It is preferably treated with 0.1~10g/L alkaline aqueous solution, and more preferably with 1~2g/L alkaline aqueous solution, such as sodium hydroxide aqueous solution, at 30~50℃ for 0.5~2 minutes. It is better to wash the copper surface with water. In addition, before oxidizing the copper surface, etching or other treatments to physically roughen the copper surface can also be performed as a pre-treatment.

Next, in the first tank (4), an oxidizing agent is used to oxidize a part or all of the copper surface to form an oxide on the copper surface. The oxidizing agent is not particularly limited, and for example, aqueous solutions of sodium chlorite, sodium hypochlorite, potassium chlorate, potassium perchlorate, potassium persulfate, etc. can be used. Various additives (for example, phosphates such as trisodium phosphate dodecahydrate) or surfactant molecules can be added to the oxidizing agent. Examples of the surfactant molecule include porphyrin, porphyrin macrocycle, expanded porphyrin, cycloporphyrin, porphyrin linear polymer, porphyrin sandwich coordination complex, porphyrin array, silane, tetraorgano-silane, aminoethyl-aminopropyl-trimethoxysilane, (3-aminopropyl)trimethoxysilane, (1-[3-(Trimethoxysilyl)propyl]urea), (3-aminopropyl)triethoxysilane, (3- Epoxypropyloxypropyl) Trimethoxysilane, (3-chloropropyl)trimethoxysilane, (3-epoxypropyloxypropyl)trimethoxysilane, dimethyldichlorosilane, 3-(trimethoxysilyl)propyl methacrylate, ethyltriethoxysilane, triethoxy(isobutyl)silane, triethoxy(octyl)silane, tris(2-methoxyethoxy)(vinyl)silane, chlorotrimethylsilane, methyltrichlorosilane, tetrachlorosilane, tetraethoxysilane, phenyltrimethoxysilane, chlorotriethoxysilane, vinyl-trimethoxysilane, amines, sugars, etc. In addition to the oxidizing agent, a solvent such as alcohols, ketones, or carboxylic acids may be used in combination. The oxidation reaction conditions are not particularly limited, and the liquid temperature of the oxidant is preferably 40~95°C, more preferably 45~80°C. The reaction time is preferably 0.5~30 minutes, more preferably 1~10 minutes.

By this oxidation treatment, the thickness of the oxide layer is 400 nm or less on average. Preferably, it is 200 nm or less on average, and more preferably, it is 160 nm or less on average. Moreover, the thickness of the oxide layer is preferably 20 nm or more on average, more preferably 30 nm or more on average, and more preferably 40 nm or more on average. In addition, the proportion of the region where the thickness of the oxide layer is 400 nm or less is not particularly limited, and preferably, more than 50% of the region is 400 nm or less, more preferably, more than 70% of the region is 400 nm or less, more preferably, more than 90% of the region is 400 nm or less, more preferably, more than 95% of the region is 400 nm or less, and more preferably, almost 100% of the region is 400 nm or less. The ratio of the oxide layer thickness can be calculated, for example, by the continuous electrochemical reduction method (SERA) from 10 measurement points in an area of 10×10 cm.

The arithmetic mean roughness (Ra) of copper oxide is preferably 0.02μm or more, more preferably 0.04μm or more, and more preferably 0.20μm or less, and more preferably 0.060μm or less. The maximum height roughness (Rz) of copper oxide is preferably 0.2μm or more, more preferably 0.4μm or more, and more preferably 1.0μm or less, and more preferably 0.5μm or less. Here, the maximum height roughness (Rz) is the sum of the maximum value of the peak height Zp and the maximum value of the valley depth Zv of the profile curve (y=Z(x)) in the reference length 1. The arithmetic mean roughness (Ra) is the average value of the absolute value of Z(x) (i.e., peak height and valley depth) in the profile curve (y=Z(x)) expressed by the following formula in the reference length 1.

Surface roughness Ra and Rz are calculated according to the method specified in JIS B 0601:2000 (based on the international standard ISO4287-1997).

Next, a reducing agent can be used in the fourth tank (5) to reduce the oxidized copper surface. The reducing agent can be DMAB (dimethylammonium borane), diborane, sodium borohydride, hydrazine, etc. The reduction treatment can be performed by a known method using a solution containing a reducing agent, an alkaline compound (sodium hydroxide, potassium hydroxide, etc.) and a solvent (pure water, etc.).

Then, a dissolution treatment is performed in the fifth tank (6) to dissolve the oxidized copper surface with a solvent. The solvent is not particularly limited, and examples thereof include chelating agents, biodegradable chelating agents, and the like. Specifically, there are EDTA (ethylenediaminetetraacetic acid), DHEG (dihydroxyethylglycine), GLDA (tetrasodium L-glutamine diacetate), EDDS (ethylenediamine-N,N'-disuccinic acid), HIDS (sodium 3-hydroxy-2,2'-iminodisuccinate), MGDA (trisodium methylglycine diacetate), ASDA (tetrasodium aspartic acid diacetate), HIDA (disodium N-2-hydroxyethyliminodiacetate), sodium gluconate, hydroxyethylidene diphosphonic acid, and the like. The solvent used in this step can be used in combination with alcohol, ketone, carboxylic acid and other solvents. The pH value of the solvent is not particularly limited, but due to the high solubility in acidic conditions, the treatment is difficult to control, and uneven treatment is easily produced, and the convex part produced by the optimal Cu/O ratio cannot be formed. Therefore, it is preferably alkaline, more preferably pH9.0~14.0, more preferably pH9.0~10.5, and more preferably pH9.8~10.2. In the fifth tank (6), the dissolution rate of copper oxide is 35~99%, preferably 77~99%, and the copper surface is preferably dissolved to a copper oxide thickness of 4~150nm, preferably 8~50nm.

Afterwards, in the second tank (7), the copper surface is electroplated with a metal other than copper. The electroplating method can use known techniques, and the metal other than copper can be, for example, tin, silver, zinc, aluminum, titanium, bismuth, chromium, iron, cobalt, nickel, palladium, gold, platinum or alloys thereof. In particular, when the object having a surface covered with copper is a copper foil, in order to have heat resistance, it is preferred to use a metal with higher heat resistance than copper, such as nickel, palladium, gold and platinum or alloys thereof. In addition, in the case of copper foil, etc., it can be plated on one side or both sides.

The average thickness of the metal layer formed by electroplating in the vertical direction is not particularly limited, but is preferably 10 nm or more, more preferably 15 nm or more, and more preferably 20 nm or more. Furthermore, it is preferably 100 nm or less, more preferably 70 nm or less, and more preferably 50 nm or less. Alternatively, the metal amount of the metal layer formed by electroplating, when expressed as the metal weight per unit area, is preferably 15 μg/cm ² or more, more preferably 18 μg/cm ² or more, and more preferably 20 μg/cm ² or more. In addition, it is preferably 100 μg/cm ² or less, more preferably 80 μg/cm ² or less, and more preferably 50 μg/cm ² or less. The average thickness of the metal layer in the vertical direction can be calculated by dissolving the metal forming the metal layer with an acid solution, measuring the metal amount by ICP analysis, and dividing the measured amount by the area of the object. Alternatively, it can also be calculated by dissolving the object itself and detecting and measuring only the amount of metal forming the metal layer.

Electroplating requires a charge to reduce a portion of the oxide layer. Therefore, for example, in the case of nickel plating copper foil, in order to keep the thickness within the optimal range, it is better to apply a charge of 15C/ ^dm2 to 90C/ ^dm2 per unit area of the object to be electroplated. In addition, the current density is preferably 5A/ ^dm2 or less. If the current density is too high, the plating will be concentrated on the protrusions, etc., making it difficult to plate uniformly. In addition, the current during the plating process can be changed until a portion of the oxide layer is reduced. In addition, the thickness can be appropriately adjusted to the specified thickness by the metal to be plated. Examples of nickel plating and nickel alloy plating include pure nickel, nickel-copper alloy, nickel-chromium alloy, nickel-cobalt alloy, nickel-zinc alloy, nickel-manganese alloy, nickel-lead alloy, and nickel-phosphorus alloy. Examples of plating ion suppliers include nickel sulfate, nickel sulfamate, nickel chloride, nickel bromide, zinc oxide, zinc chloride, diamine dichloropalladium, iron sulfate, iron chloride, anhydrous chromic acid, chromium chloride, sodium chromium sulfate, copper sulfate, copper pyrophosphate, cobalt sulfate, manganese sulfate, and sodium hypophosphite. Other additives including pH buffers or brighteners may include boric acid, nickel acetate, citric acid, sodium citrate, ammonium citrate, potassium formate, apple acid, sodium appleate, sodium hydroxide, potassium hydroxide, sodium carbonate, ammonium chloride, sodium cyanide, sodium potassium tartrate, potassium thiocyanate, sulfuric acid, hydrochloric acid, potassium chloride, ammonium sulfate, ammonium chloride, potassium sulfate, sodium sulfate. , sodium thiocyanate, sodium thiosulfate, potassium bromate, potassium pyrophosphate, ethylenediamine, nickel ammonium sulfate, sodium thiosulfate, fluorosilicic acid, sodium fluorosilicate, strontium sulfate, cresol sulfonic acid, β-naphthol, saccharin, 1,3,6-naphthalenetrisulfonic acid, sodium naphthalene disulfonate, sodium naphthalenetrisulfonate, sulfonamide, sulfinic acid, 1,4-butynediol, coumarin, sodium dodecyl sulfate, etc. The bath composition for nickel plating may preferably include, for example, nickel sulfate (100 g/L to 350 g/L), nickel sulfamate (100 g/L to 600 g/L), nickel chloride (0 g/L to 300 g/L), and mixtures thereof, and may also include sodium citrate (0 g/L to 100 g/L) or boric acid (0 g/L to 60 g/L) as an additive.

The ratio of metals in metal layers other than copper is not particularly limited. The ratio of copper to the total metal content at a depth of 6 nm is preferably 80% by weight or less, more preferably 50% by weight or less, and more preferably 30% by weight or less. In addition, the ratio of copper to the total metal content at a depth that does not contain oxygen is preferably 90% by weight or more, more preferably 95% by weight or more, and more preferably 99% by weight or more. In addition, the Cu/O ratio at a depth where the copper atomic composition ratio is 40% or more is preferably 1 or more, more preferably 2 or more, and more preferably 5 or more. The ratio of copper to the total metal content at a specified depth can be measured using, for example, ion sputtering and X-ray photoelectron spectroscopy (XPS).

The metal layer is preferably a uniform layer without particles. Here, uniform means that the layer thickness does not exceed 5 times, preferably 3 times, and more preferably 2 times the average layer thickness on more than 95% of the surface, preferably more than 98% of the surface, and more preferably more than 99% of the surface. By forming a uniform layer without particles, the adhesion after heat treatment can be improved. In addition, after the above steps, coupling treatment using silane coupling agent or rust-proofing treatment using benzotriazole or the like can be performed.

In order to obtain an oxide layer suitable for the purpose of oxide use through the above series of steps, it is better to conduct a preliminary experiment to set the temperature, time and other conditions.

Object and its surface shape: The object with copper surface to be processed may be an object formed of copper, or an object formed of an object other than copper with a copper layer on its surface, or an object plated with copper. The shape of the object is not particularly limited, for example, it may be foil, particle, powder, or copper foil such as electrolytic copper foil and rolled copper foil with copper as the main component, copper particles, copper powder, copper wire, copper plate, copper wire frame.

By processing the copper surface with the above-mentioned processing device, a convex portion is formed on the surface of at least a portion of the metal layer. The average height of the convex portion is preferably greater than 10nm, more preferably greater than 50nm, and more preferably greater than 100nm, and preferably less than 1000nm, more preferably less than 500nm, and more preferably less than 200nm. The height of the convex portion is, for example, the distance between the midpoint of the line connecting the minimum points of the concave portions adjacent to the convex portion in the image observed by a scanning electron microscope (SEM) of the cross section of the composite copper foil made by a focused ion beam (FIB) and the maximum point of the convex portion between the adjacent concave portions.

On the surface of the object, the number of protrusions with a height of 50nm or more per 3.8μm is preferably an average of 15 or more, more preferably 30 or more, and more preferably 50 or more. In addition, it is preferably 100 or less, more preferably 80 or less, and more preferably 60 or less. The number of protrusions is calculated by measuring the number of protrusions with a height of 50nm or more per 3.8μm in an image observed by a scanning electron microscope (SEM) of a cross section of a composite copper foil made by a focused ion beam (FIB).

The arithmetic mean roughness (Ra) of the metal layer is preferably 0.02μm or more, more preferably 0.04μm or more, and more preferably 0.20μm or less, and more preferably 0.060μm or less. The maximum height roughness (Rz) of the metal layer is preferably 0.2μm or more, more preferably 0.4μm or more, and more preferably 1.4μm or less, and more preferably 0.5μm or less.

In addition, the ratio of Ra after oxidation treatment to Ra after metallization treatment (Ra after oxidation treatment/Ra after metallization treatment) is preferably 0.7 or more and 1.3 or less, and the ratio of Rz after oxidation treatment to Rz after metallization treatment (Rz after oxidation treatment/Rz after metallization treatment) is preferably 0.8 or more and 1.2 or less. The closer this ratio is to 1, the more uniform the thickness of the metal layer formed by electroplating is.

Method for utilizing an object having a roughened copper surface: An object having a copper surface roughened by the processing device of the present invention can be used as copper foil used in printed wiring boards, copper wires for substrate wiring, copper foil for LIB negative electrode collectors, etc. For example, the surface of the copper foil used in the printed wiring board is roughened by the processing device of the present invention, and is adhered to a resin in a layered state to produce a laminate for use in the manufacture of printed wiring boards. The type of resin in this case is not particularly limited, and preferably polyphenylene ether, epoxy resin, PPO, PBO, PTFE, LCP or TPPI. For another example, the copper foil used for the negative electrode collector of LIB is roughened by the processing device of the present invention, thereby improving the adhesion between the copper foil and the negative electrode material, and obtaining a good lithium ion battery with less capacity degradation. The negative electrode collector for lithium ion battery can be manufactured according to known methods. For example, a negative electrode material containing a carbon-based active material is prepared and dispersed in a solvent or water to form an active material slurry. After applying this active material slurry on the copper foil, the solvent or water is evaporated and dried. After that, it is pressed, and after drying again, the negative electrode collector is formed into the desired shape. In addition, the negative electrode material may also include silicon or silicon compounds, germanium, tin or lead, etc., which have a theoretical capacity greater than that of carbon-based active materials. In addition, the electrolyte may be an organic electrolyte solution in which lithium salt is dissolved in an organic solvent, or a polymer formed by polyethylene glycol or polyvinylidene fluoride, etc. The copper foil whose surface is processed by the processing device of the present invention may be used for lithium-ion batteries as well as lithium-ion polymer batteries.

(Example) <1. Manufacturing an object with a roughened copper surface>: Examples 1 to 9 and Comparative Examples 1 to 4 use DR-WS (manufactured by Furukawa Electric Co., Ltd., thickness 18μm) copper foil. In addition, in the examples and comparative examples, several test pieces were made under the same conditions.

(1) Pretreatment: [Alkaline degreasing treatment] Immerse the copper foil in a 40g/L sodium hydroxide aqueous solution at 50°C for 1 minute, then rinse with water.

[Acid pickling] The copper foil that has undergone alkaline degreasing treatment is immersed in a 10 wt% sulfuric acid aqueous solution at a temperature of 25°C for 2 minutes, and then washed with water.

[Pre-immersion treatment] Immerse the pickled copper foil in a pre-immersion solution with a temperature of 40°C and 1.2g/L sodium hydroxide for 1 minute.

(2) Oxidation treatment: The copper foil treated with alkali is oxidized using an aqueous solution for oxidation treatment according to the conditions listed in Table 1. After the above treatment, the copper foil is washed with water. The evaluation method is described in <2. Evaluation of samples after oxidation treatment> later.

(3) Electroplating treatment: The copper foil that has been oxidized is electroplated according to the conditions listed in Table 1. Even after electroplating for 3 minutes, no nickel is precipitated in Comparative Examples 2 and 3.

(4) Coupling treatment: The copper foil that has been electroplated is subjected to coupling treatment according to the conditions listed in Table 1.

<2. Evaluation of samples after oxidation treatment>: (1) Determination of copper oxide thickness: Use QC-100 (manufactured by ECI) to measure the thickness of copper oxide on the surface of copper foil by continuous electrochemical reduction method (SERA) with the following electrolyte.

Electrolyte (pH=8.4)

Boric acid 6.18g/L; sodium tetraborate 9.55g/L

Specifically, when a pad with a diameter of 0.32 cm is used and the above electrolyte is used at a current density of 90 μA/cm ² , the potential from above -0.85 V to -0.6 V is determined to be the peak of copper oxide (CuO).

(2) Calculation of Ra and Rz: The surface shape of the copper foil after oxidation treatment was measured using a conjugate scanning electron microscope OPTELICS H1200 (manufactured by Lasertec Co., Ltd.), and Ra and Rz were calculated according to the method specified in JIS B 0601:2001. Measurement conditions: scanning width is 100μm, scanning type is Area, light source is blue light, and cut-off value is 1/5. Objective lens x100, eyepiece x14, digital zoom x1, Z distance is set to 10nm, data from 3 positions are obtained, and the average value is calculated as Ra and Rz for each example and each comparative example. Example 6 and Comparative Examples 1~3 cannot be calculated, so they are recorded as N.D. in the table.

<3. Evaluation of samples after electroplating and coupling treatment> (1) Calculation of nickel content: The average thickness of nickel in the vertical direction is measured by, for example, dissolving a copper component in 12% nitric acid and using the resulting solution to measure the concentration of metal components using an ICP emission spectrometer 5100 SVDV ICP-OES (manufactured by Agilent Technologies). The thickness of the layered metal layer is calculated by considering the metal density and the surface area of the metal layer.

(2) Calculation of Ra and Rz: The surface shape of the copper foil after electroplating and coupling treatment was measured using a conjugate scanning electron microscope OPTELICS H1200 (manufactured by Lasertec Co., Ltd.), and Ra and Rz were calculated according to the method specified in JIS B 0601:2001. Measurement conditions: scanning width is 100μm, scanning type is Area, light source is blue light, and cut-off value is 1/5. Objective lens x100, eyepiece x14, digital zoom x1, Z distance is set to 10nm, and data from 3 positions are obtained. Ra and Rz are the average values of the 3 positions.

(3) Determination of the peeling strength of the laminate before and after heat treatment: For the copper foil after electroplating and coupling treatment, a laminate was made and the peeling strength before and after heat treatment was measured. In addition, when measuring the peeling strength, the peeling surface was visually confirmed to confirm whether the coating layer was peeled. First, for each copper foil, MEGTRON6 (manufactured by Panasonic) containing PPE as a resin was heat-pressed in a vacuum at a pressure of 2.9 MPa, a temperature of 210°C, and a pressing time of 120 minutes to obtain two test samples. For each test sample, in order to know its heat resistance, a heat treatment (177°C, 10 days) was performed. Afterwards, a 90 peel test (Japanese Industrial Standard (JIS) C5016) was performed on each heat-treated sample and the non-heat-treated sample to obtain the peel strength (kgf/cm). The heat-resistant degradation rate is calculated by dividing the measured peel strength difference before and after the heat-resistant test by the peel strength before the heat-resistant test. MEGTRON6 is used as the prepreg above, but using other commercially available prepregs such as MEGTRON4 will hardly cause degradation caused by copper foil, and the same adhesion before and after heat treatment can be obtained.

(4) Calculate the color change of the copper foil before and after heat treatment: The heat resistance of the copper foil after electroplating and coupling treatment is also evaluated by color change. Specifically, the color change before and after heat treatment is evaluated by ΔE*ab after heat treatment in an oven at 225°C for 30 minutes. After measuring the color difference (L*, a*, b*) of the copper foil before heat treatment, put it in an oven at 225°C for 30 minutes, measure the color difference of the copper foil after heat treatment, and calculate ΔE*ab according to the following formula.

ΔE*ab=[(ΔL ^* ) ² +(Δa ^* ) ² +(Δb ^* ) ² ] ^1/2

Table 1

Thus, when the copper oxide thickness is 502 nm or more, electroplating is impossible (Comparative Example 2, Comparative Example 3). Moreover, even when the copper oxide thickness is electroplatable, when the copper oxide thickness is thicker than 400 nm, the adhesion between the coating layer and the metal component cannot be obtained and peeling occurs (Comparative Example 1). In contrast, in Examples 1 to 9 in which the copper oxide thickness is 400 nm or less, adhesion between the coating layer and the metal component is obtained, and adhesion to the resin and heat resistance are excellent. In addition, when the current density is greater than 5A/ ^dm2 , the heat resistance is low (Comparative Example 4). In contrast, Examples 1 to 9 in which the current density is less than 5A/ ^dm2 have excellent adhesion to the resin and heat resistance.

Industrial applicability: According to the present invention, a novel copper surface processing device can be provided.

1: Third slot

11: Scroll wheel

2: Sixth slot

3: The seventh slot

4: First slot

5: Fourth slot

6: Fifth slot

7: Second slot

8: Anode and power supply

100: Processing equipment

Claims (5)

A copper surface processing device is used for processing the surface of an object having a surface covered with copper. The processing device comprises: a first tank for oxidizing the surface so that the thickness of copper oxide is less than 400nm; and a second tank for electroplating the oxidized surface with a metal other than copper, and the current density of the electroplating treatment in the second tank is less than 5A/ ^dm2 . A copper surface processing device as claimed in claim 1, wherein the second tank has an anode and a power source. The copper surface processing device of claim 1 or 2 is also provided with a third tank, which is used to perform alkaline treatment on the surface with an alkaline aqueous solution before oxidizing the surface. The copper surface processing device of claim 1 or 2 is also provided with a fourth tank and/or a fifth tank, wherein the fourth tank is used to reduce the oxidized surface with a reducing agent after the surface is oxidized and before the electroplating treatment, and the fifth tank is used to dissolve the oxidized surface with a dissolving agent. A copper surface processing device as claimed in claim 1 or 2, wherein the object is copper foil, copper particles, copper powder, copper wire, copper plate, copper lead frame or copper-plated object.