JP2020183085A - Laminate - Google Patents

Abstract

To provide a new laminate of a composite copper member and a resin substrate.MEANS FOR SOLVING THE PROBLEM: In a laminate in which a resin substrate having a dielectric constant of 3.8 or less is layered on a surface of a copper member having a plurality of fine projections on at least a part of the surface, a fractal dimension of the layered surface of the copper member and the resin substrate is 1.25 or more.SELECTED DRAWING: None

Description

The present invention relates to a laminate.

The copper foil used for the printed wiring board is required to have adhesion to the insulating resin base material. In order to improve this adhesiveness, a method has been used in which the surface of the copper foil is roughened by etching or the like to increase the mechanical adhesive force by the so-called anchor effect. However, from the viewpoint of increasing the density of printed wiring boards and transmission loss in the high frequency band, flattening of the copper foil surface has been required. In order to satisfy these conflicting requirements, copper surface treatment methods such as performing an oxidation step and a reduction step have been developed (Patent Document 1). According to the report, the copper foil is pre-conditioned and 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 obtain copper oxide. By reducing the amount of water, the unevenness of the surface is adjusted and the roughness of the surface is adjusted. Further, as a method for improving the adhesion in the treatment of copper foil using oxidation / reduction, a method of adding a surface active molecule in the oxidation step (Patent Document 2) or copper using an aminothiazole compound or the like after the reduction step. A method of forming a protective film on the surface of a foil (Patent Document 3) has been developed. Further, a method has been developed in which the surface of a copper conductor pattern on an insulating substrate is roughened to form a plating film having metal particles dispersedly distributed on the surface on which a copper oxide layer is formed (Patent Document 4). ..

On the other hand, in the adhesion between resin and metal, in addition to mechanical adhesive force, 1) physical bond force due to intermolecular force between resin and metal, 2) covalent bond between functional group of resin and metal, etc. It is said that the chemical binding force caused by the above is also involved. Insulating resins for high-frequency circuits have a reduced proportion of OH groups (hydroxyl groups) due to their low dielectric constant and low dielectric loss tangent, but the OH groups of the resin are involved in bonding with metals, so copper foil The chemical bonding force with and is weakened (Patent Document 5). Therefore, stronger mechanical adhesive force is required for adhesion between the insulating resin for high frequency circuits and copper foil.

International Publication No. 2014/126193 Special Table 2013-534054 Japanese Unexamined Patent Publication No. 8-97559 Japanese Unexamined Patent Publication No. 2000-151096 International Publication No. 2017/150043

An object of the present invention is to provide a novel laminate of a composite copper member and a resin base material.

As a result of diligent research, the inventors of the present application have succeeded in producing a new laminate of a composite copper member and a resin base material, which has excellent peel strength and heat resistance. The present invention includes the following embodiments:
[1] A laminated body of a copper member having a plurality of fine protrusions on at least a part of the surface, wherein a resin base material having a dielectric constant of 3.8 or less is laminated on the surface.
A laminate having a fractal dimension of 1.25 or more on the laminated surface of the copper member and the resin base material.
[2] The laminate according to [1], wherein the fractal dimension of the laminate surface is larger than 1.4.
[3] The laminate according to [1] or [2], wherein at least a part of the surface of the copper member contains a copper oxide layer.
[4] A metal layer other than copper is formed on the surface of at least a part of the copper member, and the metal other than copper is Sn, Ag, Zn, Al, Ti, Bi, Cr, Fe, Co, Ni. The laminate according to [1] or [2], which is at least one metal selected from the group consisting of Pd, Au and Pt.
[5] The laminate according to [4], wherein the average thickness of the metal layer other than copper in the vertical direction is 10 nm or more and 150 nm or less.
[6] The laminate according to any one of [1] to [5], wherein the height of the convex portion is 50 nm or more and 500 nm or less on average in the vertical cross section of the laminate.
[7] The laminate according to [6], which has an average of 30 or more convex portions per 3.78 μm cross-sectional width in the vertical cross section of the laminate.
[8] The laminate according to any one of [1] to [7], wherein the resin base material contains a liquid crystal polymer containing polyphenylene ether, polytetrafluoroethylene, or parahydroxybenzoic acid.
[9] The laminate according to [8], wherein when the resin base material and the composite copper member are peeled off, the peeling mode is cohesive failure.
[10] The laminate according to [9], wherein the deterioration rate is 50% or less in a heat resistance test.
[11] The laminate according to any one of [1] to [10], which is for a high frequency circuit of 1 GHz or more.
[12] An electronic component manufactured by using the laminate according to any one of [1] to [11].

It is a figure which shows the SEM cross-section analysis image (fractal dimension) in one Example of this invention. It is a schematic diagram for demonstrating the convex shape in this invention. It is a figure which shows the shape of the convex part of the laminated surface in the SEM cross-sectional analysis image in one Example of this invention. It is a figure which shows the appearance of the test piece after a peel test in one Example of this invention. It is a figure which shows the transmission loss measurement result in one Example of this invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings, but the present invention is not necessarily limited thereto. The object, feature, advantage, and idea thereof of the present invention will be apparent to those skilled in the art 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. it can. The embodiments and specific examples of the invention described below show preferred embodiments of the present invention and are shown for illustration or explanation purposes, and the present invention is described in them. It is not limited. It will be apparent to those skilled in the art that various modifications and modifications can be made based on the description of this specification within the intent and scope of the present invention disclosed herein.

== Laminated body ==
One aspect of the present invention is a laminated body in which a resin base material having a dielectric constant of 3.8 or less is laminated on a copper member having a plurality of fine protrusions on the surface.
It is preferable that the copper member and the resin base material are in close contact with each other. For example, in a scanning electron microscope (SEM) cross-sectional image (magnification 30000 times, resolution 1024x768) in which a cross section of a laminate created by a focused ion beam (FIB) is observed, between a copper member and a layer of a resin substrate. It is preferable that no voids can be detected.

Copper members include, but are not limited to, copper foils such as electrolytic copper foils and rolled copper foils, copper wires, copper plates, and copper lead frames. A copper member is a member containing 50% by mass or more of Cu, that is, a material that becomes a part of a structure, and is a copper alloy (that is, white copper, brass, aluminum bronze, etc.) or a material coated with copper (for example, copper). Copper-plated iron) may be included, but a material made of pure copper having a Cu purity of 99.9% by mass or more is preferable, and it is more preferably formed of tough pitch copper, deoxidized copper, and oxygen-free copper. It is more preferably formed of anoxic copper having an oxygen content of 0.001% by mass to 0.0005% by mass.

The resin base material is not particularly limited, but may contain a thermoplastic resin or a thermosetting resin, and specifically, polyethylene (PE), polypropylene (PP), polystyrene (PS), or polyvinyl chloride. Weight of (PVC), polyvinyl acetate (PVAc), polyamide (PA), polyacetal (POM), polycarbonate (PC), modified polyphenylene ether (m-PPE), polyphenylene ether containing polystyrene polymer, triallyl cyanurate Combined or copolymer, phenol-added butadiene polymer, diallyl phthalate, divinylbenzene, polyfunctional methacryloyl, unsaturated polyester, polypropylene, styrene-butadiene, styrene-butadiene / styrene-butadiene crosslinked polymer, bismaleimide triazine (BT) ),
Polyethylene terephthalate (PET), fiberglass reinforced polyethylene terephthalate
(GF-PET), Polybutylene terephthalate (PBT), Cyclic polyolefin (COP), Polyphenylene sulfide (PPS), Polytetrafluoroethylene (PTFE), Polysulfone (PSF), Polyethersulfone (PES), Acrylic poly Arilate (PAR), liquid crystal polymer (LCP) (eg, polycondensate containing parahydroxybenzoic acid and ethylene terephthalate; polycondensate of parahydroxybenzoic acid, phenol and phthalic acid; parahydroxybenzoic acid and 2,6-hydroxy (Polycondensate of naphthoic acid, etc.), polyetheretherketone (PEEK), thermoplastic polyimide (PI), polyamideimide (PAI) and a substrate containing a mixture thereof can be mentioned.
The resin base material may further contain an inorganic filler or glass fiber.
The permittivity of such a resin base material can be measured by a known method, for example, IPC TM (The Institute for Interconnecting and Packaging Electronic Circuits Test Method) -650 2.5.5.5 or IPC TM-650. It can be measured according to a standard such as 2.5.5.9. As an example of the resin base material, MEGTRON6 (manufactured by Panasonic Corporation; dielectric constant 3.71 (1 GHz)) composed of 20 to 70% by weight of polyphenylene ether (PPE), 0 to 20% by weight of silica, and 30 to 70% of glass fiber is used. Can be mentioned.

It is preferable that the laminated surface of the resin base material and the metal layer has a plurality of fine convex portions. The shape of the convex portion can be defined as the fractal dimension or the radius of the inscribed circle at the tip of the convex portion. The fractal dimension can be calculated as the fractal dimension of the curve in which the laminated surface appears in the cross-sectional image created by the focused ion beam (FIB) using a scanning electron microscope (SEM). For example, the fractal dimension can be calculated using the box counting method, but the calculation method is not limited to this. The inscribed circle radius of the tip of the convex portion can be calculated by measuring the convex portion in the cross-sectional image created by the focused ion beam (FIB) using a scanning electron microscope (SEM).

The fractal dimension is an index showing the complexity of the shape, the degree of unevenness on the surface, and the like, and the larger the value of the fractal dimension, the more complicated the unevenness. For example, the fractal dimension by the box counting method is defined as:
Assuming that the number of boxes required to cover a certain figure F with a square box having a side size of δ is Nδ (F), the fractal dimension is defined by the following equation.

In the present disclosure, the cross section of the laminated body is divided by a grid of equidistant δs, and the number of boxes (that is, squares formed by the grid division) containing a curve in which the laminated surface appears is calculated for a plurality of δs. Count. Next, the size of δ is plotted on the log-log graph with the number of boxes counted for each δ as the vertical axis, and the fractal dimension can be obtained from the slope of the graph.

More specifically, the contour of the fine convex portion obtained from the SEM cross-sectional image (magnification 30000 times, resolution 1024x768) is attached to a sheet having a resolution of 256, 128, 64, 32, 16 or 8 pixels, and the cell containing the contour is attached. Count the number of. The logarithm of the pixel size is on the vertical axis, the logarithm of the number of cells is on the horizontal axis, the number of cells counted for each pixel size is plotted, an approximate straight line is created, and the fractal dimension value is calculated from the slope. ..
The value of the fractal dimension of the curve in which the laminated surface appears is 1.250 or more or greater than 1.250, or preferably 1.300 or more or greater than 1.300, and 1.350 or more or 1.350 or more. A value greater than 1.350 is more preferred, and a value greater than or equal to 1.400 or greater than 1.400 is even more preferred.

In one aspect of the present invention, the surface of the copper member may contain a copper oxide layer containing copper (I) oxide and / or copper (II) oxide. Such a copper oxide layer may be formed by an oxidation treatment, an oxidation dissolution treatment, an oxidation reduction treatment, or an oxidation dissolution reduction treatment.
The oxidation treatment includes a step of converting pure copper into copper (II) oxide with an oxidizing agent.
The dissolution treatment includes a step of dissolving copper (II) oxide oxidized by the oxidation treatment with a dissolving agent.
The reduction treatment includes a step of reducing copper (II) oxide oxidized by the oxidation treatment to copper (I) oxide or pure copper with a reducing agent.
The oxidation treatment, dissolution treatment, and reduction treatment may include a step of forming fine protrusions (that is, fine hairs) on the surface of the copper member and a step of adjusting the shape and number of the fine protrusions. The plurality of fine protrusions on the laminated surface of the resin base material and the metal layer may be caused by the fine protrusions formed by these treatments.

A metal layer other than copper may be formed on the surface of at least a part of the copper member. When the copper oxide layer is formed, the metal layer is formed on at least a part of the surface of the copper oxide layer, and a resin base material having a dielectric constant of 3.8 or less is laminated on at least a part of the surface of the metal layer. Is preferable. The type of metal constituting the metal layer is not particularly limited, but at least one metal selected from the group consisting of Sn, Ag, Zn, Al, Ti, Bi, Cr, Fe, Co, Ni, Pd, Au and Pt. Is preferable. In particular, in order to have heat resistance, metals having higher heat resistance than copper, such as Ni, Pd, Au and Pt, are preferable.

The average thickness of the metal layer in the vertical direction is not particularly limited, but is preferably 6 nm or more, and more preferably 10 nm or more, 14 nm or more, 18 nm or more, or 20 nm or more. However, if it is too thick, the fine protrusions on the surface of the composite copper member will be smoothed by leveling, the value of the fractal dimension will be small, and the adhesion will be reduced. Therefore, it is preferably 150 nm or less, preferably 100 nm or less, or It is more preferably 75 nm or less.
As a method for measuring the thickness, for example, a copper member is dissolved in 12% nitrate, and the obtained liquid is measured for the concentration of a metal component using an ICP emission spectrometer 5100 SVDV ICP-OES (manufactured by Azilent Technology). , The thickness of the metal layer as a layer can be calculated by considering the density of the metal and the surface area of the metal layer.

The metal layer may be formed on the surface of the copper member by plating. The plating method is not particularly limited, and examples thereof include electrolytic plating, electroless plating, vacuum vapor deposition, and chemical conversion treatment, but electrolytic plating is preferable.

In one aspect of the present invention, the average height of the convex portion of the curve in which the laminated surface appears in the SEM cross-sectional image of the laminated body is preferably 10 nm or more, more preferably 50 nm or more, and more preferably 100 nm or more. It is more preferably 1000 nm or less, more preferably 500 nm or less, and even more preferably 200 nm or less. The height of the convex portion is, for example, the distance between the midpoint of the line segment connecting the minimum points of the concave portions adjacent to each other across the convex portion and the maximum point of the convex portion between the concave portions in the SEM cross-sectional image. can do.
In one aspect of the present invention, the number of convex portions having a height of 50 nm or more on the curve in which the laminated surface appears in the SEM cross-sectional image of the laminated body is 25, 30 or 35 or more on average per 3.78 μm in cross-sectional width. You may. Alternatively, there may be an average of 6, 10 or 12 or more convex portions having a height of 100 nm or more per 3.78 μm cross-sectional width. Alternatively, there may be two or three or more convex portions having a height of 150 nm or more per 3.78 μm cross-sectional width.
The larger the height of the convex portion, the greater the mechanical adhesive force due to the anchor effect, which is preferable from the viewpoint of peel strength, but the influence of the skin effect phenomenon becomes large. The skin effect is a phenomenon in which the current flowing through a conductor concentrates on the surface of the conductor as the frequency increases, and the internal current density decreases. The thickness of the epidermis (epidermis depth) through which current flows is inversely proportional to the square root of frequency. Due to this skin effect phenomenon, when a high-frequency signal having a frequency in the GHz band is transmitted to a conductor circuit, the skin depth becomes about 2 μm or less, and current flows only on the very surface layer of the conductor. Therefore, in a high-frequency circuit, if the convex portion on the surface of the copper member is large, the transmission path of the conductor formed by the copper member becomes long due to the influence of the skin effect phenomenon, and the transmission loss increases. Therefore, it is desirable that the convex portion on the surface of the copper member used in the high frequency circuit is small, but if it is too small, sufficient peel strength cannot be obtained, so that the convex portion having the above degree is preferable.

In the present specification, the radius of the inscribed circle at the tip of the convex portion can be used as an index of the thickness of the convex portion. The inscribed circle radius of the tip of the fine convex portion here is parallel to the maximum point a of the convex portion having a height of 10 nm or more and the tangent line at the maximum point a of the convex portion in the SEM cross-sectional image. It is defined as the radius of a circle whose outer circumference is three points b and c, which are the intersections of a straight line 10 nm apart from each other and the outer peripheral portion of the convex portion (FIG. 2A). The larger the inscribed circle radius, the thicker the tip of the convex portion, and the smaller the inscribed circle radius, the thinner the tip of the convex portion.

In one aspect of the present invention, when the resin base material and the composite copper member are peeled off, it is preferable that at least a part of the fracture mode on the peeled surface on the composite copper member side is cohesive fracture. Here, the cohesive fracture is a state in which the resin is attached to about half or more of the area when observing the copper side of the peeled surface.

In one aspect of the present invention, the deterioration rate of the laminate in the heat resistance test may be 50% or less, but preferably 40% or less, 30% or less, or 20% or less. The deterioration rate in the heat resistance test can be measured by a known method. For example, the peel strength before and after the heat resistance test can be measured, and the difference in peel strength can be expressed as a ratio divided by the peel strength before the heat resistance test. As the heat resistance test, for example, it can be measured according to a standard such as IPC TM-650 2.4.8.

== Manufacturing method of laminated body ==
One embodiment of the present invention is a method for producing a laminate.
The first step of forming a convex portion on the surface of a copper member and
This is a method for producing a laminate, which comprises a third step of heating and adhering a resin base material on a copper surface having a convex portion or a plated surface. This manufacturing method may include a second step of plating the copper surface on which the convex portion is formed after the first step.

First, in the first step, the copper surface is oxidized with an oxidizing agent to form a copper oxide layer and a convex portion on the surface. Prior to this oxidation step, a roughening treatment step such as etching is not necessary, but it may be performed. Alkaline treatment may be performed to prevent acid from being brought into the degreasing cleaning or oxidation process. The method of alkaline treatment is not particularly limited, but is preferably 0.1 to 10 g / L, more preferably 1 to 2 g / L in an alkaline aqueous solution, for example, a sodium hydroxide aqueous solution at 30 to 50 ° C. for 0.5 to 2 minutes. It should be processed to some extent.

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 (for example, phosphates such as trisodium phosphate dodecahydrate) and surface active molecules may be added to the oxidizing agent. Surface active molecules include porphyrin, porphyrin-membered ring, expanded porphyrin, ring-reduced porphyrin, linear porphyrin polymer, porphyrin sandwich coordination complex, porphyrin sequence, silane, tetraorgano-silane, aminoethyl-aminopropyl-trimethoxysilane. , (3-Aminopropyl) trimethoxysilane, (1- [3- (trimethoxysilyl) propyl] urea) ((l- [3- (Trimethoxysilyl) propyl] urea)), (3-aminopropyl) triethoxy Silane, ((3-glycidyloxypropyl) trimethoxysilane), (3-chloropropyl) trimethoxysilane, (3-glycidyloxypropyl) trimethoxysilane, dimethyldichlorosilane, 3- (trimethoxysilyl) propylmethacrylate, Ethyltriacetoxysilane, triethoxy (isobutyl) silane, triethoxy (octyl) silane, tris (2-methoxyethoxy) (vinyl) silane, chlorotrimethylsilane, methyltrichlorosilane, silicon tetrachloride, tetraethoxysilane, phenyltrimethoxysilane, Examples thereof include chlorotriethoxysilane, ethylene-trimethoxysilane, amines, and sugars.

The oxidation reaction conditions are not particularly limited, but the liquid temperature of the oxidizing agent is preferably 40 to 95 ° C, more preferably 45 to 80 ° C. The reaction time is preferably 0.5 to 30 minutes, more preferably 1 to 10 minutes.

In the first step, the surface of the oxidized copper member may be dissolved with a dissolving agent to adjust the uneven portion of the surface of the oxidized copper member.

The solubilizer used in this step is not particularly limited, but a chelating agent, particularly a biodegradable chelating agent, is preferable, and ethylenediaminetetraacetic acid, diethanolglycine, L-glutamate diacetic acid / tetrasodium, ethylenediamine-N, N'- Examples thereof include disuccinic acid, 3-hydroxy-2, 2'-sodium iminodiacetic acid, methylglycine diacetate 3 sodium, aspartate diacetate 4 sodium, N- (2-hydroxyethyl) iminodiacetic acid disodium, sodium gluconate and the like. it can.

The pH of the solubilizer is not particularly limited, but is preferably alkaline, more preferably 8 to 10.5, still more preferably 9.00 to 10.5, and pH 9.8 to 10.2. Is more preferable.

Further, in the first step, the copper oxide layer formed on the copper member is subjected to a chemical solution containing a reducing agent (
The number and height of the convex portions may be adjusted by reducing with a chemical solution for reduction).

As the reducing agent, DMAB (dimethylamine borane), diborane, sodium borohydride, hydrazine and the like can be used. The chemical solution for reduction is a liquid containing a reducing agent, an alkaline compound (sodium hydroxide, potassium hydroxide, etc.), and a solvent (pure water, etc.).

In the second step, a composite copper member is manufactured by plating a copper oxide layer having a convex portion with a metal other than copper. As a plating treatment method, a known technique can be used. For example, as a metal other than copper, Sn, Ag, Zn, Al, Ti, Bi, Cr, Fe, Co, Ni, Pd, Au, Pt, or Various alloys can be used. The plating process is not particularly limited, and plating can be performed by electroplating, electroless plating, vacuum deposition, chemical conversion treatment, or the like.

In the case of electroless nickel plating, it is preferable to perform treatment using a catalyst. As the catalyst, iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium and salts thereof are preferably used. By performing the treatment with a catalyst, a uniform metal layer in which particles are not scattered can be obtained. As a result, the heat resistance of the composite copper member is improved. In the case of electroless nickel plating, it is preferable to use a reducing agent in which copper, copper (I) oxide and copper (II) oxide do not have catalytic activity. Examples of the reducing agent in which copper, copper (I) oxide and copper (II) oxide do not have catalytic activity include hypophosphates such as sodium hypophosphite.

The composite copper member produced in these steps may be optionally subjected to a coupling treatment using a silane coupling agent or the like or a rust preventive treatment using benzotriazoles or the like.

As a third step, a resin base material is laminated on a copper oxide layer having a convex portion formed in the first step or a plating layer of a copper member plated in the second step to produce a laminate. .. The method for producing the laminate is not particularly limited, and a known method can be used, for example, vacuum heating and crimping using a vacuum press. The press pressure, temperature, and press time are appropriately changed depending on the resin base material used. For example, in the case of MEGTRON6 (Panasonic Corporation) containing PPE resin as the resin base material, heat crimping is performed at 0.49 MPa until the temperature reaches 110 ° C. while heating, and then heat crimping is performed at 210 ° C. for 120 minutes at 2.94 MPa, PTFE. In the case of NX9255 (Park Electrochemical Co., Ltd.) containing resin, heat-bonded at 0.69 MPa until it reaches 260 ° C. while heating, and then crimped at 1.03 MPa to 1.72 MPa while heating until it reaches 385 ° C. It is recommended, but not limited to, heat crimping at 385 ° C. for 10 minutes.
A resin base material for a high frequency circuit having a dielectric constant of 3.8 or less tends to have a higher press temperature than a resin base material for a wiring board having a dielectric constant of more than 3.8 (for example, FR-4), and has fine irregularities. It becomes more susceptible to change. Copper is affected by heat, but the finer the unevenness, the greater the effect. This is because even if a change due to heat of the same degree occurs, the smaller the affected object, the greater the contribution. For example, in the case of fine unevenness, the uneven shape may be impaired after pressing and sufficient peel strength may not be exhibited. Therefore, it is required that the uneven portion has an uneven shape that can withstand the temperature at the time of pressing and can exhibit sufficient peel strength even after lamination.

As described above, by performing the first to third steps on the copper member, a new laminate of the copper member and the resin base material can be produced. Further, the copper member used in the laminated body may be wired in a pattern by a known method (for example, etching).
The laminate according to the present invention may be used in the production of a printed wiring board, or may be used in the production of an electronic component including a printed wiring board and electronic components.
The printed wiring board produced by using this laminated body is particularly suitable as a substrate for a high frequency band having a signal frequency of 1 GHz or more.
Further, since this laminated body has an uneven shape on the laminated surface, it has excellent adhesion and is also suitable for a flexible substrate.

<1. Manufacture of laminate>
In Examples 1 and 2 and Comparative Examples 1 and 2, DR-WS (manufactured by Furukawa Electric Co., Ltd., thickness: 18 μm) was used as the copper foil.

(1) Pretreatment [Alkaline degreasing treatment]
The copper foil was immersed in a sodium hydroxide aqueous solution at a liquid temperature of 50 ° C. and 40 g / L for 1 minute, and then washed with water.
[Acid cleaning treatment]
The copper foil subjected to the alkaline degreasing treatment was immersed in a sulfuric acid aqueous solution having a liquid temperature of 25 ° C. and 10% by weight for 2 minutes, and then washed with water.
[Pre-dip processing]
Preconditioning was performed at 40 ° C. for 1 minute with a 1.2 g / L aqueous sodium hydroxide solution. This is for degreasing cleaning for the purpose of reducing unevenness in the oxidation treatment.

(2) Oxidation Treatment The alkali-treated copper foil was oxidized with an aqueous solution for oxidation treatment (NaClO ₂ 130 g / L; NaOH 12 g / L) at 45 ° C. for 1 minute. After these treatments, the copper foil was washed with water. In Comparative Examples 1 and 2, after the oxidation treatment, they were immersed in a reducing agent (dimethylamine borane 5 g / L; sodium hydroxide 5 g / L) for 1 minute at room temperature to perform the reduction treatment.

(3) Plating Treatment In Examples 1 and 2, electrolytic plating was performed on the shiny surface of the oxidized copper foil using an electrolytic solution for nickel plating (nickel 470 g / L-boric acid 40 g / L). did. The conditions were 50 degrees and a current density of 0.5 A / dm ² × 30 seconds (= 15 C / dm ² per copper foil area).

(4) Heat crimping of resin base material In Example 1 and Comparative Example 1, MEGTRON6 (prepreg R5670KJ, manufactured by Panasonic, dielectric constant 3.71 (1 GHz), thickness 100 μm) was laminated on each copper foil. A laminated body was obtained by heat-pressing under the conditions of a press pressure of 2.9 MPa, a temperature of 210 ° C., and a press time of 120 minutes using a vacuum high-pressure press machine.
In Example 2 and Comparative Example 2, a PTFE base material (NX9255, manufactured by Park Electrochemical Co., Ltd., dielectric constant 2.55 (10 GHz), thickness 0.762 mm) was laminated on each copper foil, and a vacuum high-pressure press was applied. A laminate was obtained by heat-pressing under the conditions of a press pressure of 1.5 MPa, a temperature of 385 ° C., and a press time of 10 minutes using a machine.
For Examples and Comparative Examples, a plurality of test pieces were prepared under the same conditions.

<2. SEM cross-section image analysis>
1. 1. Method The cross sections of the obtained laminates (Examples 1 and 2; Comparative Examples 1 and 2) were obtained by FIB (focused ion beam) processing under the conditions of an accelerating voltage of 30 kV and a probe current of 4 nA. Using a focused ion beam scanning electron microscope (Auriga, manufactured by Carl Zeiss), the obtained cross section was observed under the conditions of a magnification of 30,000 times and a resolution of 1024x768, and an SEM cross section image was acquired. The obtained SEM cross-sectional image is shown in FIG. Based on the image of this cross section, the fractal dimension value, the height of the convex portion, and the inscribed circle radius of the tip of the convex portion were measured. Image analysis software WinROOF2018 (Mitani Corporation, Ver4.5.5) for measuring the height of the convex part and the radius of the inscribed circle at the tip of the convex part.
Was performed using. An example of measuring the radius of the inscribed circle at the tip of the convex portion is shown in FIG. 2B.

2. Results The results are shown in Tables 1 to 3 below.

<3. Peel strength measurement>
1. 1. Method The peel strength of the laminates of Examples 1 and 2 and Comparative Examples 1 and 2 was measured according to a 90 ° peeling test (Japanese Industrial Standards (JIS) C5016).

2. Results The results are shown in Table 4.
In the comparative example, the peel strength was lower than that in the example, and the fracture mode was interfacial peeling or partial interfacial peeling, whereas in the example, resin coagulation fracture was observed. As described above, the laminate according to the present invention is superior in peel strength as compared with the comparative example.

<4. Heat resistance measurement>
1. 1. Method The peel strength of the laminates of Example 1 and Comparative Example 1 was measured before and after the heat resistance test. The heat resistance test was carried out by baking at 125 ° C. for 4 hours and then floating in a solder bath at 288 ° C. for 10 seconds (IPC TM-650 2.4.8 compliant). The ratio was calculated by dividing the difference in peel strength before and after the heat resistance test by the peel strength before the heat resistance test.

2. Results The results are shown in Table 5 and FIG.
When comparing the peel strength between the normal state and the heat resistance test, 53% deterioration occurred in Comparative Example 1, but only 19% deterioration occurred in Example 1 (Table 5). Further, after the heat resistance test, discoloration was confirmed in the copper member in the comparative example (emphasized by the red line frame in FIG. 3). This is because the unevenness on the surface of the copper member was melted by the heat resistance test. As described above, the laminate according to the present invention is excellent in peel strength and heat resistance as compared with the comparative example.

<4. High frequency characteristics>
1. 1. Method As Example 1 and Comparative Example 3, copper foil FV-WS (manufactured by Furukawa Electric Co., Ltd., thickness: 18 μm, Rz: 1.2 μm) and MEGTRON6 (prepreg R5670KJ, manufactured by Panasonic, thickness 100 μm) as a resin base material. Was laminated by thermal pressure molding, and then a sample for measuring transmission characteristics was prepared and the transmission loss in the high frequency band was measured. The transmission characteristics were evaluated using a known stripline resonator method suitable for measurement in the 0 to 50 GHz band. Specifically, the S21 parameter was measured under the following conditions without a coverlay film.
Measurement conditions: Microstrip structure; Base material MEGTRON6; Circuit length 150 mm; Conductor width 250 μm; Conductor thickness 18 μm; Base material thickness 100 μm; Characteristic impedance 50 Ω

2. Results The results are shown in FIG.
The copper foil FV-WS used in Comparative Example 3 has low roughness and is a copper foil for high-frequency substrates that requires low transmission loss for information communication equipment such as high-end routers and servers and antenna substrates for communication base stations. However, the transmission loss of Example 1 is smaller than that of Comparative Example 3. As described above, the laminate according to the present invention is excellent in high frequency characteristics.

INDUSTRIAL APPLICABILITY According to the present invention, it has become possible to provide a novel laminate of a copper member and a resin base material.

(3) Plating Treatment In Examples 1 and 2, the electrolytic solution for nickel plating (nickel sulfamate ) was formed on the shiny surface (glossy surface, which is flat when compared with the opposite surface ) of the oxidized copper foil . Electroplating was performed using 470 g / L-boric acid 40 g / L). The conditions were 50 degrees and a current density of 0.5 A / dm ² × 30 seconds (= 15 C / dm ² per copper foil area).

Claims (12)

A laminated body of a copper member having a plurality of fine protrusions on at least a part of the surface, wherein a resin base material having a dielectric constant of 3.8 or less is laminated on the surface.
A laminate having a fractal dimension of 1.25 or more on the laminated surface of the copper member and the resin base material. The laminate according to claim 1, wherein the fractal dimension of the laminate surface is larger than 1.4. The laminate according to claim 1 or 2, wherein at least a part of the surface of the copper member contains a copper oxide layer. At least a part of the surface of the copper member is formed of a metal layer other than copper, and the metal other than copper is Sn, Ag, Zn, Al, Ti, Bi, Cr, Fe, Co, Ni, Pd, The laminate according to claim 1 or 2, which is at least one metal selected from the group consisting of Au and Pt. The laminate according to claim 4, wherein the average thickness of the metal layer other than copper in the vertical direction is 10 nm or more and 150 nm or less. The laminate according to any one of claims 1 to 5, wherein the height of the convex portion is 50 nm or more and 500 nm or less on average in the vertical cross section of the laminate. The laminate according to claim 6, which has an average of 30 or more convex portions per 3.78 μm cross-sectional width in the vertical cross section of the laminate. The laminate according to any one of claims 1 to 7, wherein the resin base material contains a liquid crystal polymer containing polyphenylene ether, polytetrafluoroethylene, or parahydroxybenzoic acid. The laminate according to claim 8, wherein when the resin base material and the copper member are peeled off, the peeling mode is cohesive failure. The laminate according to claim 9, wherein the deterioration rate is 50% or less in the heat resistance test. The laminate according to any one of claims 1 to 10, which is used for a high frequency circuit of 1 GHz or more. An electronic component manufactured by using the laminate according to any one of claims 1 to 11.