CN110546313A

CN110546313A - Surface treated copper foil

Info

Publication number: CN110546313A
Application number: CN201880026487.7A
Authority: CN
Inventors: 鹤田隆宏; 宇野岳夫; 奥野裕子
Original assignee: Guhe Electrical Industry Co Ltd
Current assignee: Guhe Electrical Industry Co Ltd; Furukawa Electric Co Ltd
Priority date: 2017-04-25
Filing date: 2018-04-18
Publication date: 2019-12-06
Also published as: TW201900927A; WO2018198905A1; JPWO2018198905A1; KR102340473B1; KR20190139883A; TWI745585B; JP6632739B2

Abstract

The invention provides a surface-treated copper foil. The invention aims to: the method eliminates poor adhesion due to press bonding between a copper foil and a resin, wherein the roughened surface of the copper foil is subjected to silane coupling treatment with an olefinic silane coupling agent. The present invention is a surface-treated copper foil, wherein, when measured by a contact roughness meter, the surface roughness Rz of the surface on the roughened layer side is 1.10 [ mu ] m or less, the minimum autocorrelation length Sal of the roughened surface is 0.20 [ mu ] m or more and 0.85 [ mu ] m or less, and the interfacial spreading area ratio (Sdr) of the roughened surface is in the range of 20% to 300%.

Description

Surface treated copper foil

Technical Field

The present invention relates to a surface-treated copper foil having excellent adhesion to a resin substrate made of an insulating resin, particularly a polyphenylene ether (hereinafter referred to as PPE) resin, which is used for a high-frequency compliant substrate.

Background

In recent years, with the development of high performance, and networking of computers and information communication devices, signals tend to be increased in frequency in order to perform high-speed transmission processing of large volumes of information. Such information communication devices use a copper-clad laminate. Such a copper-clad laminate is produced by heating and pressing a high-frequency-compatible insulating substrate (resin substrate) and a copper foil.

In general, a resin having excellent dielectric properties is used for an insulating substrate constituting a high-frequency copper-clad laminate such as a circuit board for a server or a router. Polyphenylene Ether (PPE) resins are used as resins having low relative permittivity and low dielectric loss tangent, and a silane coupling treatment agent for copper foil is mainly treated with an olefin silane coupling agent, because of good chemical affinity with the PPE resins. This is because a silicone crosslinked structure is formed on the surface of the copper foil by the silane coupling treatment, and the silicone crosslinked structure can be expected to function as an adhesive with the PPE-based resin.

For example, patent document 1 proposes: a heat-resistant treated layer is formed on the surface of a copper foil, and olefin-based silane coupling treatment is performed on the heat-resistant treated layer, thereby improving the adhesive strength and the rust resistance.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2003-201585

Patent document 2: japanese patent No. 4927463

Patent document 3: japanese patent No. 5242710

However, in patent document 1, although the adhesion strength which is not problematic in practical use is secured, no mention is made of the transmission characteristics which are indispensable for coping with high frequencies. In patent document 1, a copper foil having a surface roughness Rz after roughening of 1.20 μm or more is used in the examples, but if the surface roughness after roughening is too large, the skin effect (skin effect) becomes large, and this becomes a factor of lowering the transmission characteristics. Even if the adhesive strength is not problematic in practical use, when the PPE-based resin and the copper foil treated with the olefinic silane coupling agent are laminated and press-molded at high temperature in the actual production process, a local adhesion failure region called "bulge" is often generated at the interface between the copper foil and the resin, and the yield of the resin substrate is lowered. In addition, in patent document 2, although the use of a copper foil having a surface roughness of 1.10 μm or less in the examples provides transmission characteristics that are practically applicable to flexible substrate applications, there is no mention of the problem of the improvement of characteristics, such as local adhesion failure, that is, swelling, when a PPE-based resin is used.

Disclosure of Invention

problems to be solved by the invention

the present invention aims to eliminate poor adhesion in press bonding of a copper foil and a resin, particularly in press bonding of a copper foil and a resin in which a roughened surface of a copper foil is subjected to a silane coupling treatment with an olefinic silane coupling agent.

Technical scheme

In the surface-treated copper foil according to one embodiment of the present invention, when measured by a contact roughness meter, the surface roughness Rz of the roughened surface is 1.10 μm or less, the minimum autocorrelation length (Sal) of the roughened surface is in the range of 0.20 μm or more and 0.85 μm or less, and the interfacial spread area ratio (Sdr) of the roughened surface is in the range of 20% or more and 300% or less.

The present inventors have conducted investigations on the cause of swelling at the interface between the copper foil and the resin when the PPE resin and the copper foil are laminated and press-molded at high temperature, and as a result, they have found that the olefinic silane coupling agent tends to generate stress on the roughened surface and curl inward on the roughened surface side. The mechanism of stress generation on the surface by treatment with the olefinic silane coupling agent is not clear, but it is considered that: since the repulsive force between the functional groups attached to the surface of the copper foil is weak or the functional groups attract each other, stress is generated and curling occurs. It can be considered that: the stress generated at this time becomes larger at the time of pressing, and poor adhesion occurs.

It was found that a copper foil having the following surface properties is effective for solving the problem: this surface property can maintain reactivity with silane to ensure resin adhesion and disperse stress on the roughened surface side. Namely, it is known that: when the surface roughness Rz of the roughened surface of the copper foil is 1.10 μm or less, the minimum autocorrelation length (Sal) of the roughened surface is in the range of 0.20 μm or more and 0.85 μm or less, and the interfacial expansion area ratio (Sdr) of the roughened surface is in the range of 20% or more and less than 300%, when measured by a contact roughness measuring instrument, the stress on the roughened surface side can be dispersed, and the curl of the copper foil and the adhesion failure of the laminate sheet at the time of press bonding can be eliminated.

The surface roughness Rz is measured using a contact surface roughness measuring instrument. In one embodiment of the present invention, the ten-point average surface roughness Rzjis specified in JIS B0601-.

The minimum autocorrelation length (Sal) is a value specified in ISO25178, and is defined as the shortest distance in a plane in which the autocorrelation of the surface shape attenuates to a correlation value s (unless otherwise specified, the shortest distance from s1 to s 0.2) and is measured by a three-dimensional white interference microscope. Sal can be used as an index of the steepness of the surface shape of the copper foil due to the undulation of the surface of the foil before roughening, the unevenness formed by roughening, and the like. Namely, it can be said that: the smaller the value of Sal, the shorter the difference in height changes, and therefore the steeper the surface shape. In one embodiment of the present invention, the minimum autocorrelation length (Sal) was measured by gradient removal (cylindrical tilt correction) by F-operator processing, data completion (5 times repetition) and high-frequency cutoff (250KHz) by a gaussian filter at a magnification of 50 times using a white light interference type surface shape device Wyko manufactured by Bruker co.

The interfacial expansion area ratio (Sdr) is a value specified in ISO25178, is a ratio of surface area increased by surface properties based on an ideal surface having the size of a measurement region, and is defined by the following formula.

[ mathematical formula 1]

Here, x and y in the formula are plane coordinates, and z is a coordinate in the height direction. z (x, y) represents the coordinate of a certain point, and the slope at the coordinate point is obtained by differentiating the coordinate. Further, a is a plane area of the measurement region. The difference in roughness of the copper foil surface can be measured and evaluated by a three-dimensional white interference Microscope, a Scanning Electron Microscope (SEM), an Electron beam three-dimensional roughness analyzer, or the like, to obtain the interfacial spreading area ratio (Sdr). In one embodiment of the present invention, the interface spread area ratio Sdr was measured by removing the slope (column tilt correction) by F-operator processing, completing the data (conventional method (left method), repeating 5 times), and cutting off the data at a high frequency (250KHz) using a gaussian filter, using a white light interference type surface shape device Wyko manufactured by Bruker co, with a magnification of 50 times. Generally, Sdr tends to increase with the spatial complexity of the surface properties, irrespective of the change in the surface roughness Sa.

When the surface roughness Rz of the roughened surface of the copper foil is 1.10 μm or less when measured by a contact roughness measuring instrument, the swelling is less likely to occur at the interface between the copper foil and the resin when the PPE resin and the copper foil are laminated and bonded by high-temperature press. When the thickness exceeds 1.10 μm, the interface between the copper foil and the resin tends to bulge when the copper foil is press-bonded at a high temperature, resulting in poor adhesion.

When the minimum autocorrelation length Sal of the roughened surface of the copper foil is in the range of 0.20 μm or more and 0.85 μm or less, it is possible to achieve both good transmission characteristics in the case where the PPE resin and the copper foil are laminated and used as a high-frequency-compatible copper-clad laminate, and prevention of curling and contact failure during high-temperature pressing. When Sal is less than 0.20. mu.m, the steepness of the surface shape becomes too large, and the skin effect becomes large when the copper-clad laminate is used for high-frequency applications, and the transmission characteristics tend to deteriorate. On the other hand, when Sal exceeds 0.85 μm, the steepness of the surface shape is relaxed, and therefore, when the resin composition is used as a high-frequency-compatible copper-clad laminate, the skin effect is suppressed and the transmission characteristics are not problematic, but the stress is hardly dispersed by the olefinic silane coupling agent, and curling and contact failure during high-temperature pressing tend to be easily caused.

When the interfacial expansion area ratio Sdr on the roughened surface of the copper foil is in the range of 20% to 300%, it is possible to achieve both good transmission characteristics in the case where a PPE resin and a copper foil are laminated and used as a high-frequency-compatible copper-clad laminate, and prevention of curling and contact failure during high-temperature pressing. When Sdr is less than 20%, local stress on the surface on the roughened side is difficult to disperse, and the interface between the copper foil and the resin tends to bulge when the high-temperature press bonding is performed. When Sdr exceeds 300%, the skin effect becomes large when used as a high-frequency compatible copper-clad laminate, and the transmission characteristic tends to deteriorate.

Effects of the invention

According to the present invention, a surface-treated copper foil can be provided which can eliminate poor bonding when the surface-treated copper foil is press-bonded to a resin substrate and which has excellent adhesion to the resin substrate.

Drawings

Fig. 1 is a view showing a measurement site for calculating a curl value of a copper foil of an example.

Detailed Description

In the surface-treated copper foil according to another embodiment of the present invention, it is more preferable that the surface-treated copper foil according to the above-described embodiment has an interfacial spreading area ratio Sdr in the roughened surface in a range of 200% to 260%. When the interface spread area ratio (Sdr) of the roughened surface of the copper foil exceeds 200%, the stress on the roughened surface tends to be further dispersed, and the copper foil tends to be less likely to curl, and when it is less than 260%, the transmission characteristics tend to be more excellent when the copper-clad laminate is used as a high-frequency-compatible copper-clad laminate.

The surface-treated copper foil according to another embodiment of the present invention may be: in the surface-treated copper foil according to the above embodiment, the surface treatment includes an olefin-based silane coupling treatment. More suitably, in particular, the silane coupling agent is gamma-acryloxypropyltrimethoxysilane. In addition, the surface-treated copper foil according to another embodiment of the present invention has excellent adhesion to a resin substrate containing a PPE resin.

It is known that copper foil treated with an olefin-based silane coupling agent generally has good chemical affinity with PPE-based resin substrates. It can be considered that: a silicone crosslinked structure is formed on the surface of the copper foil, and the silicone crosslinked structure functions as an adhesive with the PPE-based resin. However, when the PPE-based resin and the copper foil subjected to the silane coupling treatment are laminated and subjected to high-temperature press molding as described above, a poor adhesion region called "bulge" is generated at the interface between the copper foil and the resin, and thus poor adhesion tends to occur. The copper foil according to the embodiment of the present invention has excellent adhesion to a resin substrate containing a PPE resin even when the copper foil is subjected to a silane coupling treatment with an olefinic silane coupling agent, particularly an acrylic silane.

(production of copper foil)

The copper foil used in the present invention may be any of an electrolytic copper foil and a rolled copper foil. Generally, electrolytic copper foil is widely used in printed wiring boards. In this case, the heat-resistant treatment layer and the olefinic silane coupling agent layer, which will be described later, may be formed on either the electrolytic deposition starting surface (S surface) on the roll surface side, which is the foil forming step, or the electrolytic deposition finishing surface (M surface) on the non-roll surface side. In general, the M-side is used as the adhesive surface, but the surface-treated copper foil of the present invention has excellent adhesion to a resin and excellent transmission characteristics when used as a high-frequency copper-clad laminate, regardless of which side is used as the adhesive surface, if the surface-treated copper foil is subjected to surface treatment including roughening treatment so that the interfacial spreading area ratio (Sdr) of the roughened side surface is in the range of 20% to 300%.

(formation of roughened layer)

A roughened layer having a fine uneven surface is formed on one surface of the copper foil by electrodeposition of fine copper particles. The roughened layer is formed by electroplating, and it is preferable that a chelating agent is added to the plating bath, and the concentration of the chelating agent is preferably 0.2mg/L to 0.4 mg/L. Examples of the chelating agent include: chelating agents such as DL-malic acid, EDTA (ethylenediaminetetraacetic acid) sodium solution, sodium gluconate, and diethylenetriaminepentaacetic acid (DTPA). The roughening treatment may be divided into 2 times, first plating at a relatively low copper concentration, and then roughening plating at a relatively higher copper concentration.

In the electrolytic bath, metals such as iron (Fe) and tungsten (W) are added in addition to copper sulfate and palladium (Pd) sulfate, whereby stress generated by the silane coupling agent can be dispersed, and a desired surface shape can be formed. Generally, electrodeposition is carried out under conditions of a copper concentration of 15g/L to 25g/L, a sulfuric acid concentration of 130g/L to 180g/L, a liquid temperature of 20 ℃ to 30 ℃, a current density of 30A/dm2 to 40A/dm2, and a treatment time of 5 seconds to 30 seconds.

(formation of Nickel layer, Zinc layer, chromate treatment layer)

In the present invention, it is preferable that a nickel layer and a zinc layer are further formed on the roughened surface in this order. The zinc layer serves as a heat-resistant treatment layer for preventing deterioration of the resin of the substrate and oxidation of the surface of the thin copper foil due to reaction of the resin of the thin copper foil substrate when the thin copper foil and the resin substrate are thermocompression bonded, thereby improving the bonding strength with the substrate. The nickel layer also functions as a base layer of the zinc layer to prevent the zinc of the zinc layer from thermally diffusing to the copper foil (electrolytic copper plating layer) side during thermocompression bonding to the resin substrate, thereby effectively exhibiting the above-described function of the zinc layer.

The nickel layer and the zinc layer can be formed by applying a known electroplating method or electroless plating method. In addition, the nickel layer may be formed of pure nickel or a phosphorus-containing nickel alloy.

Further, it is preferable to further chromate the surface of the zinc layer because an antioxidation layer is formed on the surface. As the chromate treatment to be applied, a known method is sufficient, and for example, a method disclosed in Japanese patent laid-open No. 60-86894 can be cited. By adhering chromium oxide or hydrate thereof in an amount of 0.01mg/dm2 to 0.3mg/dm2 as converted chromium, excellent rust inhibitive ability can be imparted to the copper foil.

(silane treatment)

the copper foil surface-treated as described above is then coated with an olefinic silane coupling agent having excellent affinity with the PPE resin to form a film of the olefinic silane coupling agent. The adhesion amount of the silane coupling agent is suitably from 0.25mg/dm2 to 0.40mg/dm2, and may also be from 0.20mg/dm2 μm to 0.50mg/dm2 μm. The coating solution is prepared using water, a weakly acidic aqueous solution, or the like as a solvent so that the concentration of the active ingredient becomes 0.001 to 10 mass%, preferably 0.01 to 6 mass%. When the content is less than 0.001 mass%, the effect of improving adhesion tends to be small, and when the content exceeds 10 mass%, the effect tends to be saturated and the solubility tends to be poor.

Examples of the olefinic silane coupling agent include: vinyl silane, acrylic silane, and methacrylic silane. The vinyl silane is vinyltrichlorosilane, vinyltrialkoxysilane, vinyldialkoxyalkylsilane, etc., for example, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (. beta. -methoxyethoxy) silane, vinyldimethoxymethylsilane, vinyldiethoxymethylsilane, etc. Examples of the acrylic silane include gamma-acryloxypropyltrimethoxysilane. Examples of methacrylic silanes include: gamma-methacryloxypropyltrimethoxysilane, gamma-methacryloxypropylmethyldimethoxysilane, gamma-methacryloxypropylmethyldiethoxysilane, gamma-methacryloxypropyltriethoxysilane, and the like. In particular, acrylic silane and the like can be used.

after the copper foil is coated with the olefinic silane coupling agent, the treated copper foil is air-dried or heat-dried. The effect of the present invention can be sufficiently exhibited by evaporation of water, but it is preferable that the drying is performed at 50 to 180 ℃ because the reaction of the silane coupling agent with the copper foil is promoted. Further, additives such as other silane coupling agents, pH adjusters, and buffers may be added and blended as needed.

The copper foil of the present invention may be pretreated with a silane treatment to form a silicone coating film. By forming the silicone coating film, the acid resistance of the copper foil can be further improved, and the adhesion strength with the insulating resin can be improved. As a method for forming a siloxane coating film, a silicate solution or a silicon compound such as tetraalkoxysilane may be diluted with a solvent such as water, methanol, ethanol, acetone, ethyl acetate, or toluene so as to be 0.001 wt% to 20 wt%, and applied to a copper foil by any method such as blowing with a sprayer, coating with a coater, dipping, or casting.

(production of copper-clad laminate)

A copper-clad laminate is produced by stacking a copper foil surface (roughened surface) on which a thin copper foil is placed on the surface of an electrically insulating substrate mixed with a resin containing a polyphenylene ether resin, for example, a polyphenylene ether resin or a polystyrene resin, and heating and pressing the copper foil surface.

Examples

The present invention will be described in further detail below with reference to examples. These examples show examples of preferred embodiments, and various modifications can be made in the practice within the scope not departing from the gist of the present invention.

(production of electrolytic copper foil)

To produce the copper foils of examples 1 to 12 and comparative examples 1 to 13, an electrolytic copper foil having a thickness of 18 μm was produced under the following conditions using a noble metal oxide-coated titanium electrode as a cathode and a titanium drum as a cathode at a current density of 50A/dm2 to 100A/dm 2.

Copper: 70g/L to 130g/L

Sulfuric acid: 80g/L to 140g/L

Additive: sodium 3-mercapto-1-propanesulfonate 1ppm to 10ppm

1ppm to 100ppm of hydroxyethyl cellulose

Low molecular weight glue (molecular weight 3000) 1ppm to 50ppm

Chloride ion concentration of 10ppm to 50ppm

Temperature: 50 ℃ to 60 DEG C

(roughening treatment)

Next, the copper foils of examples 1 to 12 were subjected to first roughening treatment 1 and then roughening treatment 2 under the following conditions.

(roughening treatment 1)

Copper sulfate (calculated as Cu concentration): 15g-Cu/L to 25g-Cu/L

Concentration of sulfuric acid: 130g/L to 180g/L

Palladium compound (calculated as palladium concentration): 0.01g-Pd/L to 0.05g-Pd/L

Iron compound (calculated as iron concentration): 0.1g-Fe/L to 0.3g-Fe/L

Tungsten compound (calculated as tungsten concentration): 0.5g-W/L to 1.5g-W/L

Liquid temperature: 20 ℃ to 30 DEG C

Current density: 30A/dm2 to 40A/dm2

(roughening treatment 2)

Copper sulfate (calculated as Cu concentration): 40g-Cu/L to 70g-Cu/L

Concentration of sulfuric acid: 80g/L to 120g/L

Liquid temperature: 20 ℃ to 30 DEG C

Current density: 1.5A/dm2 to 4A/dm2

on the other hand, the copper foils of comparative examples 1 to 4 were subjected to roughening plating based on the examples of patent document 2, and comparative examples 5 to 8 were subjected to roughening plating based on the examples of patent document 3. In addition, as for comparative examples 9 to 13, the following roughening treatment 3 and the above-described roughening treatment 2 were performed in combination, as for comparative examples 14 to 17, the following roughening treatment 4 and roughening treatment 2 were performed in combination, and as for comparative examples 18 to 21, the following roughening treatment 5 and roughening treatment 2 were performed in combination.

(roughening treatment 3)

Copper sulfate (calculated as Cu concentration): 15g-Cu/L to 25g-Cu/L

Concentration of sulfuric acid: 130g/L to 180g/L

Molybdenum compound (calculated as molybdenum concentration): 0.1g-Mo/L to 0.5g-Mo/L

Iron compound (calculated as iron concentration): 0.1g-Fe/L to 0.3g-Fe/L

Liquid temperature: 20 ℃ to 60 DEG C

Current density: 20A/dm2 to 50A/dm2

(roughening treatment 4)

Copper sulfate (calculated as Cu concentration): 15g-Cu/L to 25g-Cu/L

Concentration of sulfuric acid: 130g/L to 180g/L

Iron compound (calculated as iron concentration): 0.1g-Fe/L to 0.3g-Fe/L

Liquid temperature: 20 ℃ to 60 DEG C

Current density: 20A/dm2 to 50A/dm2

(roughening treatment 5)

Copper sulfate (calculated as Cu concentration): 15g-Cu/L to 25g-Cu/L

Concentration of sulfuric acid: 130g/L to 180g/L

Tungsten compound (calculated as tungsten concentration): 0.5g-W/L to 1.5g-W/L

liquid temperature: 20 ℃ to 60 DEG C

Current density: 20A/dm2 to 50A/dm2

(Metal plating treatment)

Next, the copper foils of examples 1 to 12 and comparative examples 1 to 21 were subjected to metal plating treatment under the following conditions in the order of nickel plating, zinc plating, and chromic acid plating.

(Nickel plating)

The primary treatment layer was performed in the following plating bath and plating conditions.

Nickel sulfate hexahydrate: 200g/L to 300g/L

Nickel chloride hexahydrate: 30g/L to 60g/L

Boric acid: 20g/L to 40g/L

Liquid temperature: 40 ℃ to 60 DEG C

Current density: 0.1A/dm2 to 10A/dm2

Energization time: 1 second to 2 minutes

(Zinc plating)

The secondary treatment layer was performed in the following plating bath and plating conditions.

Zinc sulfate heptahydrate: 1g/L to 30g/L

Sodium hydroxide: 10g/L to 150g/L

Liquid temperature: 10 ℃ to 30 DEG C

Current density: 0.1A/dm2 to 10A/dm2

Energization time: 1 second to 2 minutes

(chromic acid plating)

After the metal plating layer treatments, chromate treatment was performed under the following conditions.

Chromic anhydride: 0.1g/L to 10g/L

Liquid temperature: 20 ℃ to 40 DEG C

Current density: 0.1A/dm2 to 2A/dm2

Energization time: 1 second to 2 minutes

Next, the copper foils of examples 1 to 12 and comparative examples 1 to 21 were coated with 1 vol.% aqueous solutions of silane coupling agents belonging to the olefinic silane classes shown in table 1 at room temperature. More specifically, the aqueous solution of the silane coupling agent was allowed to flow uniformly over 1 minute with the copper foil tilted, and then, the copper foil was subjected to liquid removal by a roller and dried.

[ Table 1]

No.	Silane species
		Example 1	Gamma-acryloxypropyltrimethoxysilane
Example 2	Gamma-methacryloxypropylmethyldiethoxysilane
		Example 3	vinyl trimethoxy silane
Example 4	Vinyl tri (beta-methoxyethoxy) silane
		Example 5	Vinyl trichlorosilane
Example 6	Vinyl triethoxy silane
		Example 7	Gamma-acryloxypropyltrimethoxysilane
Example 8	Vinyl trimethoxy silane
		Example 9	Vinyl trichlorosilane
Example 10	Gamma-methacryloxypropylmethyldimethoxysilane
		Example 11	Vinyl tri (beta-methoxyethoxy) silane
Example 12	Gamma-acryloxypropyltrimethoxysilane
		Comparative example 1	Gamma-acryloxypropyltrimethoxysilane
Comparative example 2	Vinyl trichlorosilane
		Comparative example 3	Vinyl trimethoxy silane
Comparative example 4	Gamma-methacryloxypropylmethyldiethoxysilane
		Comparative example 5	Vinyl trimethoxy silane
Comparative example 6	Vinyl trichlorosilane
		Comparative example 7	Gamma-acryloxypropyltrimethoxysilane
Comparative example 8	Vinyl triethoxy silane
		Comparative example 9	Vinyl tri (beta-methoxyethoxy) silane
Comparative example 10	Gamma-methacryloxypropylmethyldimethoxysilane
		Comparative example 11	Gamma-acryloxypropyltrimethoxysilane
Comparative example 12	Vinyl tri (beta-methoxyethoxy) silane
		Comparative example 13	Gamma-acryloxypropyltrimethoxysilane
Comparative example 14	Vinyl trichlorosilane
		Comparative example 15	Vinyl triethoxy silane
Comparative example 16	Gamma-acryloxypropyltrimethoxysilane
		Comparative example 17	Vinyl trimethoxy silane
Comparative example 18	Vinyl trichlorosilane
		Comparative example 19	Gamma-methacryloxypropylmethyldimethoxysilane
Comparative example 20	Vinyl tri (beta-methoxyethoxy) silane
		Comparative example 21	Gamma-acryloxypropyltrimethoxysilane

The copper foils of examples 1 to 12 and comparative examples 1 to 21, which were subjected to the surface treatment described above, were measured for the interfacial expansion area ratio Sdr, the minimum autocorrelation length Sal, and the surface roughness Rz by the methods shown below, and then evaluated for the curl level.

(measurement of interface expansion area ratio Sdr and minimum autocorrelation Length Sal)

The slope removal (corrected by cylindrical tilt) by F-operator processing, data completion (conventional method (left method), repeated 5 times), and high frequency cutoff (250KHz) by a gaussian filter were performed at a magnification of 50 times using a white light interference type surface shape measuring apparatus Wyko manufactured by Bruker corporation to measure the interface spread area ratio Sdr and the minimum autocorrelation length Sal on the roughened surface side of the surface-treated copper foil. The measurement sites were 5 sites, and the average value of these sites was used as the measurement result. The results are shown in Table 2.

(measurement of surface roughness Rz)

As a contact surface roughness measuring device, the 10-point average roughness Rz was measured using SURFCORDER SE1700 manufactured by Okawa K.K. The results are shown in Table 2.

[ Table 2]

(evaluation of curl level)

As shown in FIG. 1, the copper foil 10 subjected to the silane coupling treatment was cut into a rectangular shape having a length of 10cm × a width of 5cm, the roughened surface (M-surface) side of the copper foil 10 was set as a surface, the copper foil was left on a horizontal table, and a stainless steel ruler (type C JIS1 grade 30cm) manufactured by Kokuyo TZ-1343 (trade name) was placed so that the width was 2cm at the left end thereof as a weight. Then, the height [ mm ] of the end portion from the rest surface of the copper foil 10 was measured for 3 total points in the longitudinal center portion (position a in the figure) and 2cm above and below the center portion (positions B and C in the figure) of the copper foil 10, and the curl value was measured by calculating the average value at 3 points.

The degree of curling obtained was evaluated according to the following criteria. That is, the test piece having a curl value of less than 0.5mm is excellent and marked as "excellent", the test piece having a curl value of 0.5mm or more and less than 1.5mm is good and marked as "o", and the test piece having a curl value of 1.5mm or more is defective and marked as "x", respectively shown in table 2.

Next, in order to evaluate the swelling and the transmission characteristics when the resin substrate was thermocompression bonded, the copper foils of examples 1 to 12 and comparative examples 1 to 21, which were subjected to the above surface treatment, were subjected to pressure bonding to the resin substrate by the following methods, and the swelling level and the transmission characteristics were evaluated.

(pressure bonding to resin substrate)

Polyphenylene ether resin and polystyrene resin were mixed at a specific ratio to prepare a resin substrate molded into a plate shape having a thickness of 0.2 mm. A copper-clad laminate composed of a surface-treated copper foil and a resin base material was produced as a test piece by a hot press molding method (press temperature 200 ℃ c., press pressure 3.0MPa) using a hot press processing machine (manufactured by toyoyo seiki corporation, MINITEST PRESS (trade name)) while overlapping the silane coupling agent-coated surface of the surface-treated copper foil with the resin base material.

(measurement of sealing Strength)

For the adhesion strength, a Tensilon tester (manufactured by a & D) was used to press the insulating substrate and the copper foil, and then the test piece was etched into a circuit pattern having a width of 10mm, and the peel strength when the circuit pattern was stretched at a speed of 50 mm/min in a 90-degree direction was measured. The number of the measurement samples was 5, and the average value of the results was set as the measurement result.

The level of adhesion strength was evaluated according to the following criteria. That is, the samples having a peel strength of 0.7kN/m or more were regarded as excellent and regarded as "excellent", the samples having a peel strength of 0.5kN/m or more and less than 0.7kN/m were regarded as good and regarded as "o", and the samples having a peel strength of 0.4kN/m or more and less than 0.5kN/m were regarded as defective and regarded as "x", and these samples are shown in table 2.

(evaluation of bulge level)

After laminating the resin base material 100mm × 100mm (1dm2) and a copper foil by hot press molding under the above conditions, the copper foil was etched using a copper chloride solution, and another polyphenylene ether resin base material was laminated on the surface where the copper foil was dissolved and removed, and hot press molding was performed to produce a test piece. The test piece was subjected to reflow heating in a reflow furnace at a maximum temperature of 260 ℃ to observe whether or not the test piece after cooling had swollen.

The level of swelling was evaluated according to the following criteria. That is, the test piece with 0 number of generated bulges/dm 2 was regarded as excellent and regarded as "excellent", the test piece with 1 to 2 number of generated bulges/dm 2 was regarded as good and regarded as "o", and the test piece with 3 number of generated bulges/dm 2 or more was regarded as defective and regarded as "x", and table 2 shows the results.

(Transmission characteristics)

After the surface-treated copper foil was laminated on a resin base material by hot press molding, a sample for measuring transmission characteristics was prepared, and transmission loss in a high frequency band was measured. For the evaluation of the transmission characteristics, the transmission loss (dB/100mm) at a frequency of 10GHz was measured by using a well-known strip line resonator method (a method of measuring S21 parameters in a state where a microstrip structure having a dielectric thickness of 50 μm, a conductor length of 1.0mm, a conductor thickness of 18 μm, a conductor circuit width of 120 μm, and a characteristic impedance of 50. omega. is not provided with a cover film) suitable for the measurement of a 1GHz to 25GHz band. The larger the transmission loss, the larger the negative absolute value. The number of the measurement samples was 5, and the average value of the results was set as the measurement result.

Based on the obtained transmission loss, the transmission characteristics were evaluated according to the following criteria. That is, a sample having a transmission loss with an absolute value of less than 16dB is excellent and marked as "excellent", a sample having a transmission loss with an absolute value of 16dB or more and less than 20dB is good and marked as "o", and a sample having a transmission loss with an absolute value of 20dB or more is defective and marked as "x", which are shown in table 2.

(comprehensive evaluation of copper foil characteristics)

The copper foil was comprehensively evaluated in consideration of the levels of the above adhesion strength, curl, bulge, and transmission characteristics according to the following criteria. That is, if there is no "x" at all and all the items are "excellent", it is "S", if "excellent" is 2 to 3, it is "a", and if "excellent" is1, it is "B". On the other hand, in the case of "x", if the number of "x" is1, "C" is assumed, "D" is assumed if 2, "E" is assumed if 3, "F" is assumed if all the items are "x", and these are shown in table 2.

As is clear from table 2, in examples 1 to 4, the curl level and the swell level were very good, and the transmission characteristics were also good. Next, in examples 5 to 8, the Sdr value was slightly smaller than that in example 1, and therefore the curl level and the bulge level were slightly inferior, but the transmission characteristics were good at a level that had no problem in quality. Further, in examples 9 to 12, the Sdr value was slightly larger than that in example 1, and therefore, the curl level and the bulge level were good, and the current skin effect was large with respect to the transmission characteristics, and therefore, the transmission characteristics were slightly inferior, but the transmission characteristics were at a level that had no problem in terms of quality.

In contrast, in comparative examples 1 to 4, since the Sdr value was 20% or less, both the curl level and the bulge level were not qualified in terms of quality. In comparative examples 5 to 8, the Sdr value exceeded 300%, and therefore there was no problem in the curl level and the bulge level, but the skin effect became too large, and the quality was not satisfactory. In comparative examples 9 to 13, the roughness Rz of the roughened surface exceeded 1.10 μm and was too large, and therefore, the curl level and the bulge level were not satisfactory regardless of the value of Sdr. The transmission loss is also not acceptable because the skin effect also becomes too large. In comparative examples 14 to 17, Sal value was too small to be less than 0.20. mu.m, and thus the skin effect became large and the transmission characteristics were not satisfactory. Further, in comparative examples 18 to 21, the Sal value exceeded 0.85 μm and was too large, and therefore the curl level and the bulge level were not satisfactory.

Industrial applicability of the invention

According to the present invention, it is possible to provide a surface-treated copper foil which can eliminate a bonding failure in press bonding a surface-treated copper foil to a resin substrate, has excellent adhesion to the resin substrate, and has excellent transmission characteristics, and thus has high industrial applicability, and a copper-clad laminate.

Description of the symbols

10 copper foil

20 ruler.

Claims

1. A surface-treated copper foil, wherein,

When measured by a contact roughness meter, the surface roughness Rz of the roughened surface is 1.10 μm or less, the minimum autocorrelation length Sal of the roughened surface is in the range of 0.20 μm or more and 0.85 μm or less, and the interfacial spreading area ratio (Sdr) of the roughened surface is in the range of 20% or more and 300% or less.

2. The surface-treated copper foil according to claim 1,

The interface spread area ratio (Sdr) is in the range of 200% to 260%.

3. The surface-treated copper foil according to claim 1 or 2,

The surface-treated copper foil has a silane coupling agent layer formed from an olefin-based silane coupling agent.

4. The surface-treated copper foil according to claim 3,

The olefin silane coupling agent is gamma-acryloxypropyltrimethoxysilane.

5. The surface-treated copper foil according to any one of claims 1 to 4, which is excellent in adhesion to a resin substrate containing a polyphenylene ether resin.

6. A surface-treated copper foil characterized in that,

The surface-treated copper foil is a surface-treated copper foil having an olefinic silane coupling agent layer on the surface thereof, and the curl value obtained by cutting the surface-treated copper foil into a rectangle having a length of 10cm × a width of 5cm, resting the surface-treated copper foil on a horizontal table with the M-side, which is the roughened surface of the surface-treated copper foil, as the surface and with the left end exposed by 2cm, placing a stainless steel ruler, measuring the height of the end portion standing from the surface on which the surface-treated copper foil is resting, for 3 total positions of the central portion in the longitudinal direction and the portions 2cm above and below the central portion, in mm, and calculating the average value of the standing heights at the 3 positions, thereby obtaining the curl value.

7. A surface-treated copper foil characterized in that,

The surface-treated copper foil is a surface-treated copper foil having an olefin-based silane coupling layer on the surface thereof,

In a copper-clad laminate obtained by laminating a mixed resin substrate having a thickness of 0.2mm and comprising a polyphenylene ether resin and the side of the olefinic silane coupling agent layer of the surface-treated copper foil, the number of measured bulges is 0,

In the measurement, the copper-clad laminate was cut to 100mm × 100mm, and a surface of the surface-treated copper foil was etched with a copper chloride solution to dissolve and remove the copper foil, and another polyphenylene ether resin base material was stacked and subjected to hot press molding to prepare a test piece, and reflow heating was performed in a reflow furnace at a maximum temperature of 260 ℃ to measure the number of the bulges generated in the test piece after cooling.