JP6083619B2 - Processed copper foil for low dielectric resin substrate, copper-clad laminate and printed wiring board using the treated copper foil - Google Patents

Description

  The present invention relates to a treated copper foil having high peel strength even with respect to a low dielectric resin base material and excellent in transmission characteristics.

  A printed wiring board used for information communication equipment or the like is obtained by forming a conductive wiring pattern on a resin base material. This resin base material is used for rigid printed wiring boards in which a reinforcing material such as glass cloth or paper is impregnated with insulating phenol resin, epoxy resin, polyphenylene ether resin, bismaleimide triazine resin, polyimide resin or cycloolefin polymer. For flexible printed wiring boards made of resin or the like.

  On the other hand, copper foil is generally used as a conductive wiring pattern material.

  This printed wiring board is made by heating and pressurizing the resin base material and copper foil to produce a copper-clad laminate and then removing unnecessary portions of the copper foil by etching to form a wiring pattern. Can do.

  Copper foils are roughly classified into two types, electrolytic copper foils and rolled copper foils, depending on the production method. In addition, any copper foil is rarely used as it is, and is provided with various treatment layers such as a roughening treatment layer, a heat-resistant treatment layer, a rust prevention treatment layer, and the like (hereinafter referred to as various types). A copper foil provided with a treatment layer is referred to as a “treatment copper foil”).

With recent information communication devices having higher functions and wider networking, signals used for information communication have become faster and higher in frequency, and there is an increasing demand for printed wiring boards that can handle high speed and high frequency.
However, high-speed and high-frequency printed wiring boards are required to have “transmission characteristics” represented by transmission loss in addition to the characteristics required for conventional printed wiring boards.

  The transmission loss indicates the degree to which the current flowing through the printed wiring board is attenuated according to the distance or the like. Generally, the transmission loss tends to increase as the frequency increases. A large transmission loss means that only a part of a predetermined current is transmitted to the load side. Therefore, in order to use it without any practical problem, the transmission loss must be kept lower.

  The transmission loss of a printed wiring board is a sum of dielectric loss and conductor loss. The dielectric loss is derived from the resin base material and is caused by the dielectric constant and the dielectric loss tangent. On the other hand, the conductor loss is derived from the conductor, that is, the copper foil, and is caused by the conductor resistance. Therefore, in order to reduce transmission loss, it is necessary to reduce the conductor resistance of the copper foil as well as the dielectric constant and dielectric loss tangent of the resin base material.

As described above, the transmission loss tends to increase as the current frequency increases. This is because the conductor loss, that is, the conductor resistance increases, and the “skin effect” and “surface shape of the treated copper foil”. Is involved.
The skin effect is an effect in which the current flowing through the conductor flows near the surface of the conductor as the frequency increases. The skin depth δ, which is defined as the distance to a point where the current is 1 / e times the current on the conductor surface, is expressed by equation (1).

δ = (2 / (ωσμ)) ^1/2 (Formula 1)

ω is the angular frequency, σ is the conductivity, and μ is the magnetic permeability.

In the case of copper, Equation (1) is as follows from its conductivity and relative permeability.

δ = 0.066 / f ^1/2 (Formula 2)

f is the frequency.

  From equation (2), it can be seen that the current flows closer to the surface of the conductor as the frequency increases. For example, when the frequency is 10 MHz, the skin depth is about 20 μm, while the frequency is 40 GHz. Is about 1 μm, and almost flows only on the surface.

  From this, when a high-frequency current is passed through a treated copper foil provided with a roughening treatment layer as in the past in order to enhance the adhesion with the resin base material, the current flows along the surface shape of the roughening treatment layer. Therefore, the propagation distance is increased as compared with the case where it mainly flows straight through the central portion, so that the conductor resistance is increased, leading to an increase in transmission loss.

  Therefore, it is necessary to keep the conductor resistance low as a treated copper foil for high-speed, high-frequency transmission-compatible printed wiring boards. For that purpose, the particle diameter of the roughened particles constituting the roughened layer is reduced, and the surface It is considered better to reduce the roughness.

Also in the resin base material, in order to suppress dielectric loss, it is better that there are few functional groups with high polarity that increase transmission loss.
A resin substrate generally called a low dielectric resin substrate contains a liquid crystal polymer, polyfluorinated ethylene, an isocyanate compound, and the like, and reduces or eliminates highly polar functional groups.

  Focusing only on the transmission characteristics, untreated copper foil without a roughened layer has a small surface roughness, so the current propagation distance can be shortened, and as a result, the resistance can be reduced. However, when focusing on the adhesiveness between the copper foil and the resin base material, those without a roughened layer have little anchoring effect and weak adhesion to the resin base material, so the peel strength Cannot be secured, and it is difficult to use it for a printed wiring board.

  In particular, the low-dielectric resin base material has a reduced or disappearance of highly polar functional groups that contribute to adhesion, and the adhesion due to chemical bonds cannot be expected. It is necessary to ensure. Furthermore, the roughened particle diameter needs to be increased in order to obtain a high adhesion force, that is, a high peel strength.

  If a roughened layer is provided on the untreated copper foil, and the adhesion amount of the roughened particles constituting the roughened layer is increased or the particle diameter is increased, the anchor effect is enhanced, so that the peeling strength is increased. However, as described above, the provision of the roughening layer increases the current propagation distance, increases the conductor resistance, and increases the transmission loss.

  In this way, in the case of a printed wiring board compatible with high-speed and high-frequency signals, if the functional group with high polarity is reduced to suppress transmission loss due to the resin base material, high adhesion with the treated copper foil cannot be obtained, and the resin base material If the particle size of the roughened particles is increased in order to improve the adhesion between the copper foil and the treated copper foil, a dilemma that transmission loss increases due to the skin effect occurs.

  However, printed wiring boards that support high-speed and high-frequency transmission must satisfy all of them in practice, and even if a low-dielectric resin substrate with few polar functional groups has sufficient peel strength, In addition, development of a treated copper foil that becomes a printed wiring board with reduced transmission loss is desired.

JP2013-155415A International Publication Number WO2003 / 102277

  Patent Document 1 discloses a treated copper foil provided with a roughening treatment layer and a heat-resistant treatment layer in order to improve adhesion with an insulating resin compatible with high-frequency transmission.

  The treated copper foil disclosed in Patent Document 1 is intended to ensure the peel strength by increasing the particles constituting the roughened layer.

  However, when the coarse particles are large, there is a problem that the transmission loss increases because the current propagation distance becomes long.

  Further, the transmission loss is further increased by the heat-resistant treatment layer, the rust-proof treatment layer, and the silane coupling agent layer, and particularly when the heat-resistant treatment layer contains Ni, the skin depth becomes shallow, so that the current is reduced to the copper foil. There is a problem that the flow is concentrated on the surface portion, and the transmission loss is further increased due to the influence of the unevenness on the surface of the treatment layer.

  In Patent Document 2, in order to improve the adhesion of a resin base material for high-frequency transmission, a roughened layer, a rust-proof layer containing zinc and nickel, a chromate layer on the rust-proof layer, and a silane on the chromate layer A treated copper foil provided with a coupling agent adsorption layer, which is intended to suppress transmission loss by adjusting the surface roughness of the treated surface to a certain range, is disclosed.

  However, since the roughening particles in the roughening layer are large, there is a problem that the current propagation distance becomes long and the transmission loss increases.

  Moreover, since Ni is contained in the rust-proofing layer, there is a problem that the skin depth becomes shallow, current flows in a concentrated manner on the surface portion of the copper foil, and transmission loss further increases.

  The present inventors made it a technical subject to solve the above-mentioned problems, and as a result of many trial and error trial manufactures and experiments, the roughened layer was formed of copper particles having a particle diameter of 300 to 600 nm. The anti-oxidation treatment layer contains molybdenum and cobalt, the ten-point average roughness Rz of the treated surface to be bonded to the low dielectric resin base material is 0.6 to 2.0 μm, and the color difference ΔE * between the untreated copper foil and the treated surface If the ab is 35 to 55 treated copper foil, it is a conductor with excellent transmission characteristics even when a roughened layer is provided, which has the same transmission loss as that of the untreated copper foil. The above technical problem has been achieved by obtaining a remarkable knowledge that high peel strength can be obtained even for a material.

  The technical problem can be solved by the present invention as follows.

  The present invention is for a low dielectric resin base material having a roughened layer on at least one surface of an untreated copper foil and an anti-oxidant layer on the roughened layer and having a dielectric loss tangent of a frequency of 1 GHz or higher of 0.005 or lower The roughened layer is formed of copper particles having a particle diameter of 300 to 600 nm, and the antioxidant layer contains molybdenum and cobalt, and has a ten-point average of the treated surfaces to be bonded to the resin base material. The roughness Rz is 0.6 to 2.0 μm, and the processed copper foil for a low dielectric resin base material having a color difference ΔE * ab between the untreated copper foil and the treated surface of 35 to 55 (Claim 1). .

Further, the present invention is the treated copper foil for a low dielectric resin base material according to claim 1, wherein one or more of the following layers a and b are provided on the antioxidant treatment layer (claim 2).
a. Chromate layer
b.Silane coupling agent layer

  Further, the present invention is a copper clad laminate in which the treated copper foil according to claim 1 or 2 is bonded to a low dielectric resin base material having a dielectric loss tangent of 1 GHz or more and 0.005 or less (claim 3).

  Further, the present invention provides a copper clad laminate according to claim 3, wherein the peel strength from a low dielectric resin base material having a dielectric loss tangent at a frequency of 1 GHz or more containing a liquid crystal polymer is 0.005 or less is 0.6 kN / m or more. (Claim 4).

Further, the present invention is a treatment method of providing a roughened layer of the treated copper foil for low dielectric resin substrate according to claim 1 or 2 by an electrolytic method, the starch decomposition product in the electrolytic solution of the electrolytic method 3. The method for treating a roughened layer of a treated copper foil for a low dielectric resin base material according to claim 1 or 2, characterized in that is added (claim 5).

  Further, the present invention provides the copper according to claim 3 or 4, wherein the treated copper foil and a low dielectric resin base material having a dielectric loss tangent of a frequency of 1 GHz or more and 0.005 or less are heated and pressed together. A method for producing a tension laminate (claim 6).

  Further, the present invention is a printed wiring board formed using the copper clad laminate according to claim 3 or 4 (claim 7).

  In the present specification, the roughened layer in the present invention may be particularly referred to as a resin-induced permeation layer.

  The treated copper foil in the present invention is a copper particle having a particle size of 300 to 600 nm of the roughened particles constituting the roughened layer (resin-induced permeation layer), and the ten-point average roughness of the treated surface to be bonded to the resin base material Rz is 0.6 to 2.0 μm, and the color difference ΔE * ab between the untreated copper foil and the treated surface is 35 to 55. Therefore, when the resin base material is heated and pressed, the resin is roughened. Even if it is a low-dielectric resin base material that penetrates uniformly between particles, the treated copper foil surface and the resin are three-dimensionally bonded in a large area, and there are few functional groups with high polarity that contribute to the peel strength, Strong peel strength can be achieved.

  In particular, a peel strength of 0.6 kN / m or more can be obtained for a low dielectric resin base material having a dielectric loss tangent of 1 GHz or more including a liquid crystal polymer of 0.005 or less.

  Further, the ten-point average roughness Rz of the treated surface to be bonded to the low dielectric resin base material of the treated copper foil in the present invention is 0.6 to 2.0 μm, the antioxidant treatment layer contains molybdenum and cobalt, nickel or the like Since it does not contain a metal that increases transmission loss, the copper clad laminate in which the treated copper foil of the present invention is laminated on a low dielectric resin base material is not provided with a roughened layer even if it has a high frequency. Transmission loss can be suppressed to the same extent as a copper clad laminate laminated with a treated copper foil.

  In particular, the copper-clad laminate bonded to a low dielectric resin base material with a dielectric loss tangent of 1 GHz or more containing liquid crystal polymer of 0.005 or less has a transmission loss of −5.5 dB / 100 mm or more at a high frequency of 40 GHz, Compared with the untreated copper foil, the transmission loss due to the resin-induced permeation layer can be suppressed to less than 5%.

It is a schematic diagram of the process copper foil cross section in this invention. It is a scanning electron micrograph of 15,000 times the cross section of the treated copper foil in the present invention.

<Untreated copper foil>
The copper foil before each treatment (hereinafter referred to as “untreated copper foil”) used in the present invention is not particularly limited, and a copper foil with no distinction between front and back and a copper foil with distinction between front and back should be used. Can do.

One surface to be surface-treated (hereinafter referred to as “treated surface”) is not particularly limited, and the rolled copper foil may be any surface, and the electrolytic copper foil may have a precipitation surface or a glossy surface. Either side is acceptable.
In addition, when using rolled copper foil, it is preferable to perform a roughening process after immersing in a hydrocarbon type organic solvent and removing rolling oil.

  Although the thickness of untreated copper foil will not be specifically limited if it is the thickness which can be used for a printed wiring board after surface treatment, 6-300 micrometers is preferable, More preferably, it is 9-70 micrometers.

  In addition, the surface of the untreated copper foil subjected to surface treatment is L * 83 to 88, a * 14 to 17, b * 15 to when measuring the color system L * a * b * defined in JIS Z8781. A range of 19 is preferred.

<Resin-induced permeation layer (roughening treatment layer)>
The particle diameter of the copper particles constituting the resin-induced permeation layer is preferably 300 to 600 nm, more preferably 380 to 530 nm.
In the present invention, the lower limit is set to 300 nm, but this does not exclude the inclusion of particles of 300 nm or less. However, if there are many particles less than 300 nm, there is a possibility that sufficient peel strength sufficient for use on a flexible printed wiring board may not be obtained when pasted on a low dielectric resin substrate. In either case, the surface roughness increases and the transmission loss increases.

  Moreover, it is preferable that the space | interval of the convex part of a copper particle is the range of 350-450 nm.

  The thickness of the resin-induced permeation layer is preferably 370 to 810 nm, more preferably 500 to 680 nm.

  If the thickness is less than 370 nm, sufficient peel strength may not be obtained, and if it exceeds 810 nm, transmission loss increases, which is not preferable in either case.

  The particle diameter of the resin-induced permeation layer, the spacing and thickness of the convex portions of the copper particles should be measured by, for example, observing and measuring the magnification at 10,000 to 30,000 times at an inclination angle of 40 ° with a scanning electron microscope or the like. Can do.

  For the formation of the resin-induced permeation layer, an electrolytic solution of copper sulfate pentahydrate 50 to 150 g / L and sulfuric acid 90 to 110 g / L is preferable.

If the concentration of copper sulfate pentahydrate is less than 50 g / L, more particles having a particle diameter of the copper particles child is less than 300nm is also one for roughening particles When it is 150 g / L or more is not formed It is not preferable.

Various additives can be added to the electrolytic solution.
Additives that can be suitably added include starch degradation products, metal sulfates, and metal oxides.

The starch decomposition product added to the electrolytic solution is not particularly limited, and may be complete decomposition or partial decomposition.
The average molecular weight is preferably from 100 to 100,000, more preferably from 100 to 10,000.

  Examples of the metal sulfate or oxide include indium sulfate, vanadium pentoxide, and germanium dioxide.

As an anode an insoluble electrode such as a platinum group oxide-coated titanium electrolytic solution immersed untreated copper foil as a cathode, a current density of 10 to 50 A / dm ^2, the amount of electricity 80~100C / dm ^2, a liquid temperature 35 to 45 ° C. It is preferable to form a resin-induced permeation layer by electrolysis under the above electrolysis conditions.

If the current density is 10 A / dm ² and the amount of electricity is lower than 80 C / dm ² , copper particles will not adhere sufficiently, and if the current density is 50 A / dm ² and the amount of electricity is higher than 100 C / dm ² , the particle diameter Since the ratio of copper particles exceeding 600 nm increases, neither is preferable.

<Antioxidation treatment layer>
The treated copper foil in the present invention includes an antioxidant treatment layer on the resin-induced permeation layer.

Adhesion amount of antioxidant treatment layer is preferably ^{30~300mg / m 2, 50~120mg / m} 2 is more preferable.

If the adhesion amount of the antioxidant treatment layer is 30 mg / m ² or less, the resin-induced permeation layer cannot be completely covered, and if it is 300 mg / m ² or more, transmission loss may increase, and 300 mg This is because an improvement in antioxidant performance cannot be expected even when the amount is more than / m ² or more.

Moreover, 20-155 mg / m < ² > is preferable for cobalt contained in the antioxidant treatment layer, and 10-145 mg / m < ² > for molybdenum is preferable.
This is because if the concentration is less than the lower limit value, the antioxidant performance is not sufficient, and if the concentration exceeds the upper limit value, transmission loss may increase.

  The electrolytic solution for forming the antioxidant treatment layer is preferably prepared by adjusting an aqueous solution containing 1 to 80 g / L of a molybdenum-containing compound to a pH of 4 to 10 in an aqueous solution of 10 to 100 g / L of a cobalt-containing compound.

  Examples of the cobalt-containing compound include cobalt sulfate heptahydrate.

  Examples of the molybdenum-containing compound include disodium molybdate dihydrate.

The electrolyte solution, an insoluble electrode such as a platinum group oxide coated titanium as an anode, immersed copper foil to form a resin derived permeation layer as a cathode, a current density of 0.1 to 10 A / dm ^2, the amount of electricity 5~20C / dm ^2, The oxidation treatment layer can be formed by electrolysis under conditions of a liquid temperature of 20 to 50 ° C.

<Chromate layer and silane coupling agent layer>
In the treated copper foil in the present invention, one or more layers selected from a chromate layer and a silane coupling agent layer can be provided on the antioxidant treatment layer as necessary.

  The electrolytic solution for forming the chromate layer is preferably prepared by adjusting the pH of the chromic acid-containing compound to 10 to 100 g / L.

  Examples of the chromic acid-containing compound include sodium dichromate dihydrate.

Chromate layer is immersed as an anode an insoluble electrode such as a platinum group oxide-coated titanium electrolytic solution, a copper foil to form an anti-oxidation treatment layer as a cathode, a liquid temperature 20 to 50 ° C., a current density of 0.1 to 10 A / dm ² It can be formed by electrolysis under the condition of an electric quantity of 0.5 to 20 C / dm ² .

  Note that zinc may be contained in the chromate layer.

  A silane coupling agent layer can be provided on the chromate layer or the antioxidant treatment layer.

  The silane coupling agent used in the silane coupling agent layer is not particularly limited, and includes a vinyl group, an epoxy group, a styryl group, a methacryl group, an acrylic group, an amino group, a ureido group, and a mercapto group. However, the amino group, epoxy group or vinyl group-containing silane coupling agent has very high effects of moisture absorption resistance and rust prevention, and can be used more suitably.

  One silane coupling agent may be used, or two or more silane coupling agents may be used in combination.

  After immersing in a silane coupling agent aqueous solution prepared at a liquid temperature of 20 to 50 ° C. or after spraying by a method such as spraying, it can be formed by washing with water.

<Resin substrate>
The low dielectric resin base material for laminating the treated copper foil in the present invention is a resin base material in which a large polar functional group contributing to adhesion between the copper foil and the resin base material is reduced or eliminated, and 1 GHz A resin substrate having a dielectric loss tangent of 0.005 or less at the above frequency.

  Examples of the low dielectric resin base material include a resin containing a liquid crystal polymer, polyfluorinated ethylene, an isocyanate compound, and a modified polyphenylene ether.

<Measurement of color difference ΔE * ab>
After measuring the color system L * a * b * defined in JIS Z8781 of the untreated copper foil surface and the treated copper foil treated surface, ([ΔL *] ² + [Δa *] ² + [ Δb *] ² ) ^1/2 can be calculated.

  Examples of the present invention are shown below, but the present invention is not limited thereto.

<Untreated copper foil>
As an untreated copper foil of Examples and Comparative Examples, a rolled copper foil or an electrolytic copper foil having a thickness of 12 μm was used.
The rolled copper foil was immersed in a hydrocarbon-based organic solvent for 60 seconds to remove the rolling oil and then subjected to each treatment.

(Examples 1 to 6)
<Formation of resin-induced permeation layer>
Table 1 electrolyte solution was made the adjustment described. Titanium whose surface is coated with platinum group oxide is used for the anode, untreated copper foil is used for the cathode, both electrodes are immersed in each electrolytic solution, and electrolysis is performed under each electrolytic condition described in Table 1. A resin-induced permeation layer was formed on one surface of the untreated copper foil.
As the starch degradation product, a mixture of degradation products having a molecular weight of 100 to 10,000 was used.

<Cobalt-molybdenum-containing antioxidant treatment layer>
Cobalt sulfate heptahydrate 38g / L, disodium molybdate dihydrate 23g / L, trisodium citrate dihydrate 45g / L, pH 5.6 containing sodium sulfate 80g / L, liquid temperature 30 ° C Using a treated copper foil with a platinum group oxide surface coated as an anode and a resin-induced permeation layer on the cathode, an electric current density of 7.0 A / dm ² and an electric charge of 14 C A cobalt-molybdenum-containing antioxidant treatment layer was provided on the resin-induced permeation layer under the electrolytic conditions of / dm ² .

<Chromate layer>
Using chromate aqueous solution prepared at pH 12.0 with sodium hydroxide, sodium dichromate dihydrate 40g / L aqueous solution with a liquid temperature of 30 ° C, and titanium coated with platinum group oxide on the anode. , Using a treated copper foil with a resin-induced permeation layer and a cobalt-molybdenum-containing anti-oxidation treatment layer on the cathode, cobalt under electrolysis conditions of current density 2.0 A / dm ² and electric quantity 10 C / dm ² for both electrodes -A chromate layer was provided on the molybdenum-containing antioxidant treatment layer.

<Silane coupling agent layer>
A treated copper foil provided with each treatment layer was immersed in an aqueous solution containing 5 ml / L of γ-aminopropyltriethoxysilane at a liquid temperature of 30 ° C. for 10 seconds to form a silane coupling agent layer on the chromate layer.

  After forming the silane coupling agent layer, it was naturally dried at a temperature of about 25 ° C. to obtain a treated copper foil of each example.

(Comparative Example 1)
It was created under the same conditions as in Example 1 except that the resin-induced permeation layer was not provided.

(Comparative Example 2)
Untreated copper foil is immersed in an electrolytic solution consisting of 47 g / L copper sulfate pentahydrate and 100 g / L sulfuric acid, and electrolysis is performed under electrolysis conditions of current density 50 A / dm ² , electric quantity 130 C / dm ² , and liquid temperature 30 ° C. After forming a fine particle layer, it is immersed in an electrolytic solution consisting of copper sulfate pentahydrate 200 g / L, sulfuric acid 100 g / L, current density 5 A / dm ² , electric quantity 400 C / dm ² , liquid temperature 40 ° C. It was produced under the same conditions as in Example 1 except that the resin-induced permeation layer was formed by electrolysis under the above electrolysis conditions.

(Comparative Example 3)
After preparing an electrolytic solution consisting of copper sulfate pentahydrate 55g / L and diethylenetriaminepentaacetic acid pentasodium 100g / L with sulfuric acid to pH 4.5, untreated copper foil was immersed in a current density of 1.4A / dm ² , electricity It was produced under the same conditions as in Example 1 except that a resin-induced permeation layer was formed by electrolysis under the electrolytic conditions of an amount of 85 C / dm ² and a liquid temperature of 32 ° C.

(Comparative Example 4)
Immerse untreated copper foil in an electrolyte solution consisting of copper sulfate pentahydrate 45 g / L, sulfuric acid 80 g / L, titanyl sulfate 2 g / L, sodium tungstate dihydrate 0.045 g / L, and current density 10 A / dm ² After forming a fine particle layer by electrolysis under an electrolysis condition of 50C / dm ² and a liquid temperature of 35 ° C, an electric current is immersed in an electrolytic solution of copper sulfate pentahydrate 200g / L and sulfuric acid 100g / L. It was produced under the same conditions as in Example 1 except that the resin-induced permeation layer was formed under electrolytic conditions of a density of 10 A / dm ² , an amount of electricity of 250 C / dm ² , and a liquid temperature of 40 ° C.

(Comparative Example 5)
Prepare an electrolyte solution consisting of copper sulfate pentahydrate 61 g / L, cobalt sulfate heptahydrate 29 g / L, nickel sulfate hexahydrate 49 g / L, sodium sulfate 80 g / L with sulfuric acid to pH 2.5. After that, it was the same as Example 1 except that the untreated copper foil was immersed and electrolyzed under electrolysis conditions of current density 5 A / dm ² , electric quantity 45 C / dm ² , and liquid temperature 30 ° C. to form a resin-induced permeation layer. It was produced under the conditions of

(Comparative Example 6)
Except for immersing an untreated copper foil in the electrolyte of Comparative Example 5 and forming a resin-induced permeation layer by electrolysis under electrolysis conditions of a current density of 5 A / dm ² , an amount of electricity of 105 C / dm ² and a liquid temperature of 30 ° C. It was produced under the same conditions as in Example 1.

(Comparative Example 7)
An electrolytic solution consisting of nickel sulfate hexahydrate 30 g / L, sodium hypophosphite monohydrate 2.0 g / L, sodium acetate trihydrate 10 g / L was adjusted to pH 4.5 with sulfuric acid, It was produced under the same conditions as in Example 1 except that the oxidation treatment layer was formed by electrolysis under the conditions of density 5.0 A / dm ² , electric quantity 10 C / dm ² , and liquid temperature 30 ° C.

(Comparative Example 8)
Electrolyte prepared from nickel sulfate hexahydrate 55g / L, cobalt sulfate heptahydrate 22g / L, adjusted to pH 3.0 with sulfuric acid, current density 5.0A / dm ² , electric charge 10C / dm ^2. It was produced under the same conditions as in Example 1 except that the oxidation treatment layer was formed by electrolysis under an electrolytic condition of a liquid temperature of 40 ° C.

(Comparative Example 9)
The treated copper foil of Comparative Example 3 is laminated with a non-low dielectric polyimide resin.

(Reference Examples 1-6)
The treated copper foils of Examples 1 to 6 are laminated with a polyimide resin that is not low dielectric.

<Copper-clad laminate A>
A liquid crystal polymer resin substrate (produced by Kuraray Co., Ltd.) having a dielectric loss tangent at 25 GHz by a triplate line resonator of 0.002 for each treated surface of each treated copper foil of Examples 1 to 6 and Comparative Examples 1 to 8 as an adherend surface. Product name: CT-Z, 50μm thickness), preheated under vacuum (7torr) at 260 ° C for 15 minutes using a vacuum heat press (KVHC-II manufactured by Kitagawa Seiki), then under vacuum (7 torr), temperature 300 ° C., pressure 4 MPa, heating and pressure molding were performed for 10 minutes to obtain a copper clad laminate A.
Copper-clad laminate A was used to measure the peel strength.

<Copper-clad laminate B>
The treated surfaces of each treated copper foil of Examples 1 to 6 and Comparative Examples 1 to 8 were combined with a liquid crystal polymer resin substrate (manufactured by Kuraray Co., Ltd., product name: CT-Z, thickness 50 μm), and each treated copper was combined. After matching the copper foil for grounding (70μm) on the other side of the foil, using a vacuum heat press machine, preheat for 15 minutes at 260 ° C under vacuum (7torr), then under vacuum (7torr), A copper-clad laminate B was obtained by heating and pressure molding at a temperature of 300 ° C. and a pressure of 4 MPa for 10 minutes.
Copper-clad laminate B was used to measure transmission loss.

<Copper laminate C>
Each treated surface of each treated copper foil of Comparative Example 9 and Reference Examples 1 to 6 was used as an adherend surface, and after matching with a polyimide resin substrate (manufactured by Kaneka Corporation, product name: FRS-142, thickness 25 μm), vacuum Using a hot press machine, preheat for 15 minutes at 260 ° C under vacuum (7torr), then heat and press mold under vacuum (7torr), 300 ° C, pressure 4MPa for 10 minutes, and copper-clad Laminate C was obtained.

  Evaluation of untreated copper foil or treated copper foil was performed by the following method.

<Measurement of surface roughness>
For each surface provided with a treated layer of untreated copper foil or treated copper foil, surf coder SE1700α (manufactured by Kosaka Laboratory Co., Ltd.) that conforms to the stylus type surface roughness meter specified in JIS B0651-2001 A ten-point average roughness Rz defined in JISB0601-1994 was measured with a stylus tip radius of 2 μm as the stylus and a cut-off value for the roughness curve of 0.8 mm and a measurement distance of 4.0 mm.

<Measurement of particle size>
Using a scanning microscope SEM (JEOL JSM-6010LA) and observing the sample stage at a magnification of 10,000 to 30,000 while tilting the sample stage by 40 °, the observed length of the copper particle group constituting the resin-induced permeation layer The average value obtained by measuring 10 points was taken as the particle size value.

<Color difference ΔE * ab>
Using a spectrocolorimeter (CM-600d manufactured by Konica Minolta), the color system L * a * b * defined in JIS Z8781 of each treated copper foil is measured, and the L * a * b of untreated copper foil A color difference ΔE * ab (= ([ΔL *] ² + [Δa *] ² + [Δb *] ² ) ^1/2 ) from * was determined.

  The copper clad laminate was evaluated by the following method.

<Stripping strength>
Using an etching machine (SPE-40, manufactured by Ninomiya System Co., Ltd.), a copper circuit sample having a width of 1 mm was produced by etching. In accordance with JIS C6481, the peel strength was measured using a universal testing machine.

<Transmission loss>
Using an etching machine, single-ended microstrip lines were formed by etching. The circuit width of the substrate was 110 μm for the copper-clad laminate B and 50 μm for the copper-clad laminate C so that the characteristic impedance was 50Ω. The S circuit (S21) having a frequency of 160 MHz to 40 GHz was measured on the fabricated circuit board using a network analyzer (N5247A manufactured by Agilent Technologies).

The evaluation results are shown in Table 2.

  From Examples 1 to 6, the transmission loss of the treated copper foil in the present invention is comparable to that of the treated copper foil (Comparative Example 1) that does not include the resin-induced permeation layer, and the treated copper foil in the present invention has a low dielectric constant. It was confirmed to have high peel strength with the conductive resin substrate.

The treated copper foil in the present invention is an excellent conductor having a transmission loss comparable to that of the untreated copper foil, but has a low dielectric resin group that has few functional groups with a large polarity that contribute to adhesion and is difficult to obtain high peel strength. Even if it is a material, since high peeling strength can be implement | achieved, the copper clad laminated board which can be used conveniently also for a flexible printed wiring board can be provided.
Therefore, the treated copper foil of the present invention is an invention with high industrial applicability.

1 Copper foil 2 Resin-induced permeation layer 3 Antioxidation treatment layer

Claims (7)

A treated copper foil for a low dielectric resin base material having a roughening treatment layer on at least one surface of the untreated copper foil and an anti-oxidation treatment layer on the roughening treatment layer and having a dielectric loss tangent of a frequency of 1 GHz or more of 0.005 or less The roughening treatment layer is formed of copper particles having a particle diameter of 300 to 600 nm, and the antioxidant treatment layer contains molybdenum and cobalt, and the ten-point average roughness Rz of the treatment surface to be bonded to the resin substrate is A treated copper foil for a low dielectric resin base material having a color difference ΔE * ab of 35 to 55 between 0.6 and 2.0 μm and the untreated copper foil and the treated surface. 2. The treated copper foil for a low dielectric resin substrate according to claim 1, wherein one or more of the following layers a and b are provided on the antioxidant treatment layer.
a. Chromate layer
b.Silane coupling agent layer A copper-clad laminate obtained by bonding the treated copper foil according to claim 1 or 2 to a low dielectric resin base material having a dielectric loss tangent of 1 GHz or more and 0.005 or less. 4. The copper clad laminate according to claim 3, wherein the peel strength from the low dielectric resin base material having a dielectric loss tangent of 1 GHz or more containing liquid crystal polymer of 0.005 or less is 0.6 kN / m or more. A processing method for providing a roughened layer of the copper foil for low dielectric resin substrate according to claim 1 or 2 by an electrolytic method, wherein a starch decomposition product is added to the electrolytic solution of the electrolytic method The method for treating a roughened layer of the treated copper foil for a low dielectric resin substrate according to claim 1 or 2. 5. The method for producing a copper-clad laminate according to claim 3, wherein the treated copper foil and a low dielectric resin base material having a dielectric loss tangent of a frequency of 1 GHz or more and 0.005 or less are pressed and bonded together while being heated. . A printed wiring board formed using the copper-clad laminate according to claim 3 or 4.