阅读说明：本技术 铜表面的加工装置 (Processing device for copper surface ) 是由 小锻冶快允 佐藤牧子 于 2020-05-07 设计创作，主要内容包括：本发明的目的在于提供一种新型的铜表面的加工装置。本发明的加工装置是针对具有被铜覆盖的表面的物体的上述表面的加工装置,该加工装置具有用于将上述表面氧化的第一槽、和用于对经过氧化的上述表面进行电镀处理的第二槽。(The invention aims to provide a novel copper surface processing device. The processing apparatus of the present invention is directed to a processing apparatus for processing the surface of an object having a surface covered with copper, the processing apparatus including a first tank for oxidizing the surface and a second tank for plating the oxidized surface.)

1. A machining device for a surface of an object having a surface covered with copper, the machining device comprising:

a first groove for oxidizing the surface; and

a second tank for performing an electroplating process on the oxidized surface.

2. The processing apparatus as set forth in claim 1, wherein:

the current density of the electroplating treatment in the second tank is 5A/dm²The following.

3. The processing apparatus according to claim 1 or 2, wherein:

the second tank has an anode and a power source.

4. The processing apparatus according to any one of claims 1 to 3, wherein:

having a third bath for alkali treatment of the surface with an aqueous alkali solution prior to oxidizing the surface.

5. The processing apparatus according to any one of claims 1 to 4, wherein:

there is a fourth tank for reducing the oxidized surface with a reducing agent and/or a fifth tank for dissolving the oxidized surface with a dissolving agent after oxidizing the surface and before performing an electroplating process.

6. The object according to any one of claims 1 to 5, wherein:

the object is copper foil, copper particles, copper powder, copper wire, copper plate, copper lead frame or copper-plated object.

Technical Field

The present invention relates to a copper surface processing apparatus.

Background

The copper foil used for the printed wiring board is required to have adhesion to a resin. In order to improve the adhesion, a method of roughening the surface of the copper foil by etching or the like to improve the physical bonding strength is used. However, from the viewpoint of high density of printed wiring boards and transmission loss in high frequency bands, the surface of copper foil is required to be planarized. In order to satisfy such contradictory requirements, a copper surface treatment method has been developed in which an oxidation step, a reduction step, and the like are performed (WO2014/126193 publication). In this way, the copper foil is pretreated, immersed in a chemical solution containing an oxidizing agent to oxidize the surface of the copper foil to form irregularities of copper oxide, and then immersed in a chemical solution containing a reducing agent to reduce the copper oxide, thereby adjusting the irregularities of the surface and adjusting the surface roughness. Further, as a method for improving adhesion in the treatment of a copper foil by oxidation-reduction, a method of adding a surface active molecule in an oxidation step (japanese patent application laid-open No. 2013-534054) and a method of forming a protective coating on the surface of a copper foil using an aminothiazole compound or the like after a reduction step (japanese patent application laid-open No. 8-97559) have been developed. Further, a method has been developed in which the surface of a copper conductor pattern on an insulating substrate is roughened, and a plating film having metal particles distributed discretely is formed on the surface having a copper oxide layer by electroless plating (see patent document 4).

Generally, the oxide of a metal has a higher resistance than the unoxidized metal. For example, pure copper has a resistivity value of 1.7X 10^-8(Ω m), 1-10 (Ω m) of copper oxide, and 1 × 10 of cuprous oxide⁶～1×10⁷(Ω m), the conductivity of both copper oxide and cuprous oxide is inferior to that of pure copper. Therefore, in the case of using oxidation treatment for roughening the surface of the copper foil, electroless plating is used as a plating method instead of electroplating (japanese patent application laid-open No. 2000-151096). On the other hand, when the surface of the copper foil is roughened by adhering copper particles to the copper foil by electroplating, since no oxide is present on the surface of the copper foil, another metal can be plated on the roughened surface of the copper foil by electroplating again (japanese patent No. 5764700 and japanese patent No. 4948579).

The plating film is required to have adhesion to such an extent that it can withstand the use and environment and has no practical problem. As a method therefor, a method is known in which a metal bond is reinforced by removing an oxide layer on the metal surface, and adhesion is secured by performing surface roughening to disperse stress (a method for improving adhesion of a plating film "とそ of adhesion of an めっき film" ("method for improving adhesion of a plating film" and method for improving the same ")).

Disclosure of Invention

Technical problem to be solved by the invention

The invention aims to provide a novel copper surface processing device.

Technical solution for solving technical problem

In general, when an oxide layer is present on the metal surface, the metal foil is not directly plated but is subjected to oxide removal by acid treatment or the like before the oxide is removed for the reason that the conductivity is deteriorated or the adhesion between the metal foil and the metal plating layer is difficult to obtain. This is because it is generally known that adhesion between a metal and a metal plating layer can be secured by a metal bond, and if an oxide layer is present at the interface between the metal and the plating metal, the metal bond between the metal and the plating metal is inhibited, and it is difficult to obtain adhesion. Further, if the metal is smooth, stress propagates so as to concentrate at the interface between the metal and the plating metal, and interface peeling is likely to occur.

On the other hand, an interface having irregularities has no clear surface for transmitting stress unlike a smooth surface. It is considered that a part of the energy is used to deform the plating metal or the metal during the energy transfer, and the energy is consumed thereby to improve the adhesion force.

As a result of intensive studies, the inventors of the present invention have found that, by forming an oxide layer formed on the surface of copper to an average of 400nm or less by using the processing apparatus of the present invention and successfully forming a metal coating on the surface of the oxide layer by electroplating, the influence of deterioration of the electrical conductivity and the resistance of metal bonds is minimized, and the adhesion between the metal and the plated metal can be improved by the anchor effect due to the fine uneven shape. Conventionally, there are techniques and apparatuses for performing oxidation treatment, reduction treatment, or plating treatment on a copper surface, but there are no treatment techniques for performing plating treatment after performing oxidation treatment, and there are no processing apparatuses therefor. Thus, the inventors of the present invention have completed the invention of a novel copper surface processing apparatus.

One embodiment of the present invention is directed to a processing apparatus for processing the surface of an object having a surface covered with copper, the processing apparatus including a first tank for oxidizing the surface and a second tank for plating the oxidized surface. The second tank may have an anode and a power source. The method may further comprise a third bath for alkali-treating the surface with an aqueous alkali solution before oxidizing the surface. There may be further provided a fourth tank for reducing the oxidized surface with a reducing agent and/or a fifth tank for dissolving the oxidized surface with a dissolving agent after oxidizing the surface and before performing the plating treatment. The object may be a copper foil, copper particles, copper powder or a copper-plated object.

Cross reference to related documents

The present invention is based on the priority claim of japanese patent application No. 2019-089118, filed on 5/9/2019, the contents of which are incorporated by reference in the present specification.

Drawings

Fig. 1 is a schematic view showing a first bath for oxidizing a surface and a second bath for plating the oxidized surface according to an embodiment of the present invention.

Fig. 2 is a schematic view of the entire processing apparatus according to an embodiment of the present invention.

Fig. 3 is a schematic view of the conveying roller provided between the tanks in one embodiment of the present invention.

Fig. 4 is a schematic view of a squeeze roller provided to a conveyance roller in one embodiment of the present invention.

Fig. 5 is a schematic view of a guide roller provided to the conveyance roller in one embodiment of the present invention.

Fig. 6 is a graph showing the relationship between the thickness of the oxide layer and the peel strength in examples and comparative examples.

Fig. 7 is a graph showing the relationship between the thickness of the oxide layer and the thermal deterioration resistance rate in examples and comparative examples.

FIG. 8 is a graph showing the thickness of the oxide layer and the thermal discoloration resistance Δ E in examples and comparative examples^＊ab relationship.

Detailed Description

Hereinafter, embodiments of the present invention will be described in detail with reference to examples. Further, the object, features, advantages and concept of the present invention can be obtained from the description of the present specification, and those skilled in the art can easily reproduce the present invention from the description of the present specification. The embodiments of the invention and specific examples described below are preferred embodiments of the invention, and are shown for the purpose of illustration and description, and the invention is not limited thereto. Those skilled in the art will appreciate that various modifications can be made based on the description of the present specification within the spirit and scope of the present invention disclosed in the present specification.

Device for machining copper surfaces

One embodiment of the present invention is directed to a processing apparatus (100) for an object having a surface covered with copper, the processing apparatus having at least a first tank (4) for oxidizing the surface and a second tank (7) for plating the oxidized surface. Before the first tank (4), a third tank (1) for alkali treatment of the copper surface with an aqueous alkali solution may be provided. Further, a sixth tank (2) for performing a cleaning treatment using an acid and a seventh tank (3) for performing a weak alkali treatment may be provided next to the third tank (1). Then, the first tank (4) can be followed, and thereafter an eighth tank (5) for reducing the oxidized copper surface with a reducing agent and/or a ninth tank (6) for dissolving the oxidized copper surface with a dissolving agent can be provided between the second tank (7). More than 1 rinsing bath may be provided between the baths and/or at the beginning and end of the total treatment. Further, it is preferable that each tank has a heating unit and a timer, and thus, the temperature and time of the process in each tank can be set. The operation of each tank in the processing of the copper surface will be described below with reference to fig. 2, which is a schematic view of the entire apparatus having 1 each of all the tanks except the water washing tank and using a roll to roll (roll) conveyance system. The device structure is an example, and all the means that can be understood by those skilled in the art according to the present invention are included in the technical scope of the present invention. For example, although 1 groove is provided for each type in fig. 2, a plurality of grooves may be provided for each type.

In addition, in the case of performing continuous processing on copper parts like a roll-to-roll conveying system, the copper parts are electrified for plating from the rolls, but the electrified part is not limited to the immediate front or the immediate back of the second tank (7) for plating processing, and the electrification may be performed from the rolls of other tanks.

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

In the sixth tank (2), the copper surface is subjected to a cleaning treatment using an acid in order to remove the natural oxide film and reduce the treatment unevenness. Therefore, the sixth tank (2) is made of a material resistant to the acid used.

In the seventh tank (3), the copper surface is subjected to an alkali treatment using a weak alkali solution in order to reduce treatment unevenness and prevent an acid used in the cleaning treatment from being mixed into the oxidizing agent. Therefore, the third tank (1) is made of a material resistant to the alkali used.

In the first tank (4), an oxidation treatment is performed in which the surface of copper is oxidized with an alkaline solution containing an oxidizing agent to form an oxide on the surface of copper. The first tank (4) is therefore made of a material resistant to the oxidizing agent and the base used. The first groove (4) may have a structure in which only a part of the surface of the copper member is subjected to oxidation treatment. For example, the copper part may be transported horizontally relative to the solution surface so that the non-treated surface is not in contact with the liquid. Alternatively, a liquid retaining member (for example, sponge) capable of containing an alkaline solution containing an oxidizing agent may be disposed in the first bath (4), and the oxidation treatment may be performed by bringing only a part of the surface of the copper member into contact with the liquid retaining member without directly immersing the copper member in the solution.

In the eighth tank (5), the oxidized copper surface is subjected to a reduction treatment using an alkaline solution containing a reducing agent. This is to reduce the copper oxide formed on the copper foil and to adjust the number and length of the irregularities. Therefore, the eighth tank (5) is made of a material resistant to the reducing agent and the alkali used.

In the ninth tank (6), a dissolving treatment is performed to dissolve the oxidized copper surface with a dissolving agent. Therefore, the ninth tank (6) is made of a material resistant to the dissolving agent used. The purpose of the dissolution treatment is to adjust the convex portions of the oxidized copper surface.

In the second tank (7), the surface of copper is plated with a metal other than copper. The second tank (7) has an anode for electrolysis and a power supply. The type of anode is not particularly limited, and may be an insoluble anode such as a pB plate or a noble metal oxide film Ti, or a soluble anode which dissolves itself and is plated on a copper foil or the like.

The water in the rinsing tank can be heated to the same or similar temperature as the water in the front and rear tanks, thereby preventing wrinkles caused by a difference in thermal expansion.

The solution used in the tank other than the second tank may be stored in the tank to impregnate the copper surface, or may be sprayed onto the copper surface by a spray device provided in the tank. In the case where the solution is stored in the tank, it is preferable to provide a liquid circulation device in the tank. This can reduce treatment unevenness caused by the solution.

In fig. 2, when the surface of copper such as copper foil is processed, the copper foil is conveyed between the grooves by a roll-to-roll conveying system. Fig. 3 shows an enlarged view of the roller (11). The conveying conditions in this case are not particularly limited, and for example, the linear velocity of the copper foil may be set to 50 to 3000m/hr, and the tension of the copper foil may be set to 1 to 130 kgf/m. In this system, a squeeze roll (12) as shown in fig. 4 may be provided. This can squeeze out the liquid from the copper foil, thereby reducing the liquid introduced into the next groove. Further, a guide roller (13) as shown in fig. 5 may be provided. This prevents the occurrence of longitudinal wrinkles and breakage of the copper foil.

The inter-tank conveyance of the object having the copper surface to be treated is not limited to the roll-to-roll conveyance system, and may be performed manually or by a conveyor such as a conveyor belt.

A drying device for drying the copper surface after the completion of all the steps may be provided. The drying temperature is not particularly limited, and the copper surface may be dried at room temperature to about 230 ℃.

Method for processing copper surface

A method of processing a copper surface using the processing apparatus described above will be described. Here, in order to process only the copper surface of the portion to be processed, only the portion may be treated by immersing the portion in each liquid or the like. In addition, a known method (japanese patent application laid-open nos. 2010-236037 and 2004-232063) can be used to perform plating treatment only on one surface of a copper foil or the like.

First, the copper surface is subjected to an alkali treatment in a third tank (1) using an aqueous alkali solution. The method of alkali treatment is not particularly limited, and the treatment may be carried out using an alkali aqueous solution of preferably 30 to 50g/L, more preferably 40g/L, for example, an aqueous sodium hydroxide solution at 30 to 50 ℃ for about 0.5 to 2 minutes. The copper surface is then preferably washed with water.

Next, the copper surface subjected to the alkali treatment may be subjected to a cleaning treatment with an acid in the sixth tank (2). For example, the copper surface is immersed in 5 to 20 wt% sulfuric acid at a liquid temperature of 20 to 50 ℃ for 1 to 5 minutes. The copper surface is then preferably washed with water.

Subsequently, the copper surface may be subjected to a weak alkali treatment in a seventh bath (3). The method of the alkali treatment is not particularly limited, and the copper surface may be treated with an alkali aqueous solution, for example, an aqueous sodium hydroxide solution, preferably 0.1 to 10g/L, more preferably 1 to 2g/L, at 30 to 50 ℃ for about 0.5 to 2 minutes. The copper surface is then preferably washed with water.

Before the copper surface is oxidized, the copper surface may be physically roughened by etching or the like as a pretreatment.

Then, oxidation treatment is performed in the first bath (4) to oxidize part or all of the copper surface with an oxidizing agent to form an oxide on the copper surface. The oxidizing agent is not particularly limited, and for example, an aqueous solution of sodium chlorite, sodium hypochlorite, potassium chlorate, potassium perchlorate, or the like can be used. Various additives (e.g., phosphate salts such as trisodium phosphate dodecahydrate) or surface active molecules may be added to the oxidizing agent. Examples of the surface active molecule include porphyrin, macrocyclic porphyrin, expanded porphyrin, contracted porphyrin, linear porphyrin polymer, porphyrin sandwich coordination complex, porphyrin array, silane, tetraorgano-silane, aminoethyl-aminopropyl-trimethoxysilane, ((3-aminopropyl) trimethoxysilane), 1- [3- (Trimethoxysilyl) propyl ] urea (l- [3- (Trimethoxysilyl) propyl ] urea), (3-aminopropyl) triethoxysilane, (3-glycidoxypropyl) trimethoxysilane, (3-chloropropyl) trimethoxysilane, (3-glycidoxypropyl) trimethoxysilane, dimethyldichlorosilane, 3- (Trimethoxysilyl) propyl methacrylate, ethyltriacetoxysilane, and mixtures thereof, Triethoxy (isobutyl) silane, triethoxy (octyl) silane, tris (2-methoxyethoxy) (vinyl) silane, chlorotrimethylsilane, methyltrichlorosilane, silicon tetrachloride, tetraethoxysilane, phenyltrimethoxysilane, chlorotriethoxysilane, ethylene-trimethoxysilane, amines, sugars, and the like. In addition, as the oxidizing agent, a solvent such as alcohol, ketone, carboxylic acid, or the like may be used in combination. The oxidation reaction conditions are not particularly limited, and the liquid temperature of the oxidizing agent is preferably 40 to 95 ℃, and more preferably 40 to 90 ℃. The reaction time is preferably 0.5 to 30 minutes, more preferably 1 to 10 minutes.

By this oxidation treatment, the average particle diameter is 400nm or less. Preferably, the average particle diameter is 200nm or less, more preferably 160nm or less. The thickness of the oxide layer is preferably 20nm or more on average, more preferably 30nm or more on average, and still more preferably 40nm or more on average. The proportion of the region having a thickness of 400nm or less is not particularly limited, but is preferably 50% or more and 400nm or less, more preferably 70% or more and 400nm or less, still more preferably 90% or more and 400nm or less, still more preferably 95% or more and 400nm or less, and still more preferably almost 100% or less and 400nm or less.

The ratio of the thickness of the oxide layer can be calculated, for example, by a continuous electrochemical reduction method (SERA) for 10 measurement points in an area of 10 × 10 cm.

The arithmetic average roughness (Ra) of copper oxide is preferably 0.02 μm or more, more preferably 0.04 μm or more, and preferably 0.20 μm or less, more preferably 0.060 μm or less.

The maximum height roughness (Rz) of copper oxide is preferably 0.2 μm or more, more preferably 0.4 μm or more, and is preferably 1.0 μm or less, more preferably 0.50 μm 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 l.

The arithmetic average roughness (Ra) is an average of absolute values of z (x) (i.e., peak height and valley depth) in a profile curve (y ═ z (x)) represented by the following formula in the reference length l.

Surface roughness Ra, Rz is measured by JIS B0601: 2001 (according to the method specified in International Standard ISO 4287-1997).

Subsequently, the oxidized copper surface may be subjected to a reduction treatment using a reducing agent in the eighth tank (5). As the reducing agent, DMAB (dimethylamine borane), diborane, sodium borohydride, hydrazine, or the like can be used, and reduction treatment can be performed by a known method using a solution containing a reducing agent, a basic compound (for example, sodium hydroxide or potassium hydroxide), and a solvent (for example, pure water or a buffer solution).

Next, in the ninth tank (6), a dissolving treatment is performed in which the oxidized copper surface is dissolved by a dissolving agent. The dissolving agent is not particularly limited, and examples thereof include a chelating agent, a biodegradable chelating agent, and the like, and specifically, EDTA (ethylenediaminetetraacetic acid), DHEG (dihydroxyethylglycine), GLDA (tetrasodium L-glutamic diacetate), EDDS (ethylenediamine-N, N '-disuccinic acid), HIDS (sodium 3-hydroxy-2, 2' -iminodisuccinate), MGDA (trisodium methylglycinediacetate), ASDA (tetrasodium aspartate diacetate), HIDA (disodium N-2-hydroxyethyliminodiacetate), sodium gluconate, etidronic acid (hydroxyethane diphosphonic acid), and the like. The solvent used in this step may be used in combination with a solvent such as alcohol, ketone, or carboxylic acid. The pH of the dissolving agent is not particularly limited, but is preferably alkaline, more preferably pH9.0 to 14.0, further preferably pH9.0 to 10.5, and further preferably pH9.8 to 10.2, because the amount of the dissolving agent is large under acidic conditions, and thus the treatment is difficult to control, the treatment is likely to be uneven, and a convex portion or the like having an optimum Cu/O ratio cannot be formed. In the ninth tank (6), the surface of copper is preferably dissolved until the dissolution rate of copper oxide reaches 35 to 99%, preferably 77 to 99%, and the thickness of CuO reaches 4 to 150nm, preferably 8 to 50 nm.

Then, the copper surface is subjected to plating treatment using a metal other than copper in the second tank (7). The plating method may use a known technique, and for example, as a metal other than copper, Sn, Ag, Zn, Al, Ti, Bi, Cr, Fe, Co, Ni, Pd, Au, Pt, or an alloy thereof may be used. Particularly when the object having a surface covered with copper is a copper foil, in order to impart heat resistance thereto, metals having heat resistance higher than that of copper, such as Ni, Pd, Au, and Pt, or alloys thereof, are preferable. In the case of copper foil or the like, the plating may be performed 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 10nm or more, more preferably 15nm or more, and still more preferably 20nm or more. Further, it is preferably 100nm or less, more preferably 70nm or less, and further preferably 50nm or less.

Alternatively, the amount of metal in the metal layer formed by electroplating is preferably 15 μ g/cm when the weight of the metal per unit area is used as the metal²Above, more preferably 18. mu.g/cm²More preferably 20. mu.g/cm²The above. Further, it is preferably 100. mu.g/cm²Less than, more preferably 80. mu.g/cm²The concentration is preferably 50. mu.g/cm or less²The following.

The average thickness of the metal layer in the vertical direction can be calculated by dissolving the metal forming the metal layer with an acidic solution, measuring the amount of the metal by ICP analysis, and dividing the measured amount by the area of the object. Alternatively, it can be calculated by dissolving the object itself, and detecting and measuring only the amount of the metal forming the metal layer.

Since electric charges are also required for reducing the oxide portion of the oxide layer during electroplating, for example, when nickel plating is performed on a copper foil, it is preferable to give a thickness of 15C/dm per unit area of the object to be subjected to electroplating treatment to a preferable range²Above 90C/dm²The following charge.

In addition, the current density is preferably 5A/dm²The following. When the current density is too high, plating is performed on a convex portion group or the like, and uniform plating is difficult to achieve. In addition, the current at the time of coating the plating layer may be changed until the oxide portion of the oxide layer is reduced. Further, the thickness is adjusted to a predetermined thickness according to the metal to be coated.

As the nickel plating and the nickel-plated alloy, there may be mentioned pure nickel, Ni-Cu alloy, Ni-Cr alloy, Ni-Co alloy, Ni-Zn alloy, Ni-Mn alloy, Ni-Pb alloy, Ni-P alloy and the like.

Examples of the plating ion supplying agent include nickel sulfate, nickel sulfamate, nickel chloride, nickel bromide, zinc oxide, zinc chloride, dichlorodiamminepalladium, iron sulfate, iron chloride, anhydrous chromic acid, chromium chloride, sodium chromium sulfate, copper pyrophosphate, cobalt sulfate, manganese sulfate, and sodium hypophosphite.

Examples of the other additives including a pH buffer and a gloss agent include boric acid, nickel acetate, citric acid, sodium citrate, ammonium citrate, potassium formate, malic acid, sodium malate, 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 thiocyanate, sodium thiosulfate, potassium bromate, potassium pyrophosphate, ethylenediamine, ammonium nickel sulfate, sodium thiosulfate, fluorosilicic acid, sodium fluorosilicate, strontium sulfate, cresolsulfonic acid, β -naphthol, saccharin, 1,3, 6-naphthalenetrisulfonic acid, sodium naphthalene (di, tri) sulfonate, 1-4 butynediol such as sulfonamide and sulfinic acid, coumarin, and sodium lauryl sulfate.

In the case of nickel plating, the bath composition preferably contains nickel sulfate (100g/L to 350 g/L), nickel sulfamate (100g/L to 600 g/L), nickel chloride (0g/L to 300 g/L) and a mixture thereof, and may contain sodium citrate (0g/L to 100 g/L) and/or boric acid (0g/L to 60 g/L) as an additive.

The ratio of the metal in the metal layer other than copper is not particularly limited, and the ratio of Cu is preferably 80 wt% or less, more preferably 50 wt% or less, and further preferably 30 wt% or less with respect to the total metal amount at a depth of 6 nm. The proportion of Cu is preferably 90% by weight or more, more preferably 95% by weight or more, and still more preferably 99% by weight or more, based on the total metal amount at a depth where no oxygen is contained. The Cu/O ratio at a depth at which the atomic composition ratio of Cu is 40% is preferably 1 or more, more preferably 2 or more, and further preferably 5 or more. The proportion of Cu with respect to the total metal amount at a prescribed depth can be measured, for example, by ion sputtering and X-ray photoelectron spectroscopy (XPS).

The metal layer is preferably a uniform layer free of particles. The term "uniform" means that the thickness of a layer is not more than 5 times, preferably not more than 3 times, or more preferably not more than 2 times the average thickness of the layer, and is 95% or more, preferably 98% or more, and more preferably 99% or more of the surface. By forming a uniform metal layer without particles, the adhesion after heat treatment can be improved.

After these steps, a coupling treatment with a silane coupling agent or the like and/or an anticorrosive treatment with a benzotriazole or the like may be performed.

It is preferable to set conditions such as temperature and time in advance in a test experiment so that an oxide layer suitable for the purpose of use of the oxide can be obtained through the series of steps.

Object and surface shape thereof

The object having a copper surface to be processed may be an object made of copper, an object having a copper layer provided on a surface of an object made of a substance other than copper, or an object subjected to copper plating, and the shape of the object is not particularly limited, and may be, for example, foil, pellet, powder, or a copper foil such as an electrolytic copper foil or rolled copper foil containing copper as a main component, copper pellet, copper wire, copper plate, or copper lead frame.

By processing the copper surface by the processing apparatus, a convex portion is formed on at least a part of the surface of the metal layer.

The average height of the projections is preferably 10nm or more, more preferably 50nm or more, and still more preferably 100nm or more, and is preferably 1000nm or less, more preferably 500nm or less, and still more preferably 200nm or less. The height of the protrusion may be, for example: in a Scanning Electron Microscope (SEM) image of a cross section of a composite copper foil produced by Focused Ion Beam (FIB), the distance between the midpoint of a line segment connecting the minimum points of adjacent recesses sandwiching a projection and the maximum point of the projection located between the recesses is measured.

On the surface of the object, the number of projections having a height of 50nm or more is preferably 15 or more, more preferably 30 or more, and further preferably 50 or more on average per 3.8 μm. Further, the number of the cells is preferably 100 or less, more preferably 80 or less, and further preferably 60 or less. The number of convex portions can be counted, for example, by counting the number of convex portions having a height of 50nm or more per 3.8 μm in a Scanning Electron Microscope (SEM) image of a cross section of the composite copper foil obtained by Focused Ion Beam (FIB).

The arithmetic average roughness (Ra) of the metal layer is preferably 0.02 μm or more, more preferably 0.04 μm or more, and preferably 0.20 μm or less, more preferably 0.060 μm or less.

The maximum height roughness (Rz) of the metal layer is preferably 0.2 μm or more, more preferably 0.4 μm or more, and is preferably 1.4 μm or less, more preferably 0.50 μm or less.

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

Method for using an object having a roughened copper surface

The object having the roughened copper surface by the processing apparatus of the present invention can be used for a copper foil used for a printed wiring board, a copper wire wired on a substrate, a copper foil for an LIB negative electrode current collector, and the like.

For example, the processing apparatus of the present invention can be used for manufacturing a printed wiring board by roughening the surface of a copper foil used for a printed wiring board and bonding the copper foil to a resin in a layered form to produce a laminated board. The type of resin used in this case is not particularly limited, but polyphenylene ether, epoxy, PPO, PBO, PTFE, LCP, or TPPI is preferable.

In addition, for example, by roughening the surface of the copper foil used for the LIB negative electrode current collector using the processing apparatus of the present invention, the adhesion between the copper foil and the negative electrode material is improved, and a good lithium ion battery with little capacity deterioration can be obtained. The negative electrode current collector for a lithium ion battery can be produced by a known method. For example, a negative electrode material containing a carbon-based active material is prepared, and dispersed in a solvent or water to prepare an active material slurry. After the active material slurry was coated on a copper foil, drying was performed to evaporate the solvent or water. Then, the negative electrode current collector is pressed and dried again, and then formed into a desired shape. The negative electrode material may contain silicon or a silicon compound, germanium, tin, lead, or the like, which has a larger theoretical capacity than the carbon-based active material. The electrolyte may be not only an organic electrolytic solution in which a lithium salt is dissolved in an organic solvent, but also an electrolyte using a polymer made of polyethylene oxide, polyvinylidene fluoride, or the like. The copper foil whose surface has been processed using the processing apparatus of the present invention is suitable not only for a lithium ion battery but also for a lithium ion polymer battery.

Example < 1. production of an object having a roughened copper surface >

In examples 1 to 9 and comparative examples 1 to 4, a DR-WS (manufactured by Kogaku corporation, thickness: 18 μm) copper foil was used. In the examples and comparative examples, a plurality of test pieces were prepared under the same conditions.

(1) Pretreatment

[ alkali degreasing treatment ]

The copper foil was immersed in a 40g/L aqueous solution of sodium hydroxide at a liquid temperature of 50 ℃ for 1 minute and then washed with water.

[ acid cleaning treatment ]

The copper foil after the alkali degreasing treatment was immersed in a 10 wt% sulfuric acid aqueous solution at a liquid temperature of 25 ℃ for 2 minutes and then washed with water.

[ Pre-impregnation treatment ]

The copper foil after the acid cleaning treatment was immersed in a chemical solution for prepreg of 1.2g/L sodium hydroxide (NaOH) at a liquid temperature of 40 ℃ for 1 minute.

(2) Oxidation treatment

The copper foil subjected to the alkali treatment was subjected to oxidation treatment using an aqueous oxidation treatment solution based on the conditions described in table 1. After these treatments, the copper foil was washed with water.

The evaluation method is described in < 2. evaluation of the sample after oxidation treatment >.

(3) Electroplating treatment

The copper foil after the oxidation treatment was subjected to the plating treatment based on the conditions described in table 1. In comparative examples 2 and 3, no nickel was deposited even after 3 minutes of plating.

(4) Coupling treatment

The copper foil after the plating treatment was subjected to a coupling treatment under the conditions described in table 1. < 2. evaluation of sample after Oxidation treatment >

(1) Determination of the thickness of the copper oxide

The thickness of copper oxide on the surface of the copper foil was measured by the continuous electrochemical reduction (SERA) method using QC-100 (manufactured by ECI) using the following electrolyte.

Electrolyte (pH 8.4)

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

Specifically, the gasket diameter is used: 0.32cm and at current density: 90 muA/cm²When the above-mentioned electrolyte is used, the potential is determined to be from-0.85V to-0.6VBreaking into a peak of copper oxide (CuO).

(2) Calculation of Ra and Rz

The surface shape of the oxidized copper foil was measured using a confocal scanning electron microscope opterlics H1200 (manufactured by Lasertec Corporation), and the surface shape was measured according to JIS B0601: 2001, Ra and Rz were calculated. As measurement conditions, the scan width was 100 μm, the scan type was an area, the Light source (Light source) was Blue, and the cutoff value was 1/5. The data at 3 were acquired with the objective lens set to x100, the contact lens set to x14, the digital zoom set to x1, and the Z pitch set to 10nm, and the average values thereof were taken as Ra, Rz for each example and comparative example. Since it could not be calculated in example 6 and comparative examples 1 to 3, it is denoted as n.d. in the table.

< 3. evaluation of samples after plating and coupling treatment >

(1) Calculation of the amount of Nickel

As a method for measuring the average thickness of nickel in the vertical direction, for example, a copper member was dissolved in 12% nitric acid, the concentration of a metal component was measured with respect to the obtained liquid by an ICP emission spectrometer 5100SVDV ICP-OES (agilent technologies, ltd.), and the thickness of a metal layer as a layer was calculated in consideration of the density of the metal and the surface area of the metal layer.

(2) Calculation of Ra and Rz

The surface shape of the copper foil after the plating and coupling treatment was measured by a confocal scanning electron microscope opterlics H1200 (manufactured by Lasertec Corporation), and the surface shape was measured according to JIS B0601: 2001, Ra and Rz were calculated. As measurement conditions, the scanning width was 100 μm, the scanning type was an area, the light source was Blue, and the cutoff value was 1/5. Data at 3 were acquired with the objective lens set to x100, the contact lens set to x14, the digital zoom set to x1, and the Z pitch set to 10nm, Ra, Rz being the average at 3.

(3) Measurement of peeling Strength before and after Heat treatment of laminate

The copper foil after the plating and coupling treatment was laminated to measure the peel strength before and after the heat treatment. When the peel strength was measured, the peeled surface was visually checked to confirm whether or not the plating layer was peeled. First, for each copper foil, MEGTRON6 (manufactured by SONGHUO Co., Ltd.) containing PPE as a resin was laminated by heating and pressure bonding under vacuum at a pressure of 2.9MPa, a temperature of 210 ℃ and a pressing time of 120 minutes, to obtain 2 measurement samples. Each of the 1 measurement samples was heat-resistant treated (177 ℃ C. for 10 days) to examine the heat resistance. Then, the samples after heat treatment and the samples without heat treatment were subjected to a 90 ° peel test (japanese industrial standard (JIS) C5016) to determine the peel strength (kgf/cm). The heat deterioration resistance rate was calculated as the ratio of the difference between the peel strengths before and after the heat resistance test divided by the peel strength before the heat resistance test.

Although MEGTRON6 was used as the resin sheet, deterioration due to the copper foil hardly occurred even when other commercially available resin sheets such as MEGTRON4 were used, and similar adhesion before and after heat treatment could be obtained.

(4) Calculation of color change before and after Heat treatment of copper foil

The heat resistance of the copper foil after the plating and coupling treatment was also evaluated by color change. Specifically, the heat treatment was carried out in an oven at 225 ℃ for 30 minutes by Δ E^＊ab colour change before and after evaluation. Measuring the color difference (L) of the copper foil before heat treatment^＊、a^＊、b^＊) Then, the copper foil was put into an oven at 225 ℃ for 30 minutes, and the color difference of the heat-treated copper foil was measured to calculate Δ E by the following formula^＊ab。

ΔE^＊ab＝[(ΔL^＊)²+(Δa^＊)²+(Δb^＊)²]^1/2

[ Table 1]

As described above, when the thickness of copper oxide is 502nm or more, electroplating cannot be performed (comparative examples 2 and 3). Further, even if the thickness of copper oxide is such that plating can be performed, when the thickness of copper oxide is greater than 400nm, adhesion between the plating layer and the metal member cannot be obtained, and peeling occurs (comparative example 1). On the other hand, in examples 1 to 9 in which the thickness of copper oxide was 400nm or less, adhesion between the plating layer and the metal member was obtained, and adhesion to the resin and heat resistance were excellent.

And, when the current density is more than 5A/dm²In contrast, the alloy had a low heat resistance (comparative example 4) and had a current density of 5A/dm²In examples 1 to 9 below, the adhesion to resin and heat resistance were excellent.

Industrial applicability

The present invention can provide a novel copper surface processing apparatus.