JP6632739B2 - Surface treated copper foil - Google Patents

Description

  The present invention relates to a surface-treated copper foil having excellent adhesion to an insulating resin of a high-frequency-compatible substrate, particularly a resin substrate containing a polyphenylene ether (hereinafter, PPE) -based resin.

  2. Description of the Related Art In recent years, as computers and information communication devices have become more sophisticated and more sophisticated, and as networking has progressed, signals have tended to have higher frequencies in order to transmit and process large amounts of information at high speed. Such information communication devices use copper-clad laminates. Such a copper-clad laminate is manufactured by heating and pressing a high-frequency compatible insulating substrate (resin substrate) and a copper foil.

  Generally, a resin having excellent dielectric properties is used for an insulating substrate constituting a high-frequency compatible copper-clad laminate such as a circuit board for a server or a router. Polyphenylene ether (PPE) -based resin is used as a resin having a low relative dielectric constant and a low dielectric tangent. However, olefin-based silane coupling agent is mainly used as a silane coupling agent for copper foil due to its good chemical affinity with PPE-based resin. Treatment with a coupling agent is employed. This is because a siloxane cross-linking structure is formed on the surface of the copper foil by the silane coupling treatment, and it can be expected that this function as an adhesive with the PPE-based resin.

  For example, Patent Document 1 proposes that a heat-resistant treatment layer is formed on the surface of a copper foil, and an olefin-based silane coupling treatment is performed thereon, thereby improving the adhesive strength and rust prevention.

JP-A-2003-201585 Patent No. 4927463 Patent No. 5242710

  However, Patent Document 1 does not refer to transmission characteristics indispensable for high-frequency use, although the adhesion strength has no practical problem. Patent Literature 1 deals with a copper foil having a surface roughness Rz after roughening of 1.20 μm or more in the examples. However, if the surface roughness after roughening becomes excessive, the skin effect becomes large, so that the transmission characteristics are increased. Is a factor of decrease. In addition, even if the adhesion strength has no practical problem, in the actual manufacturing process, when the copper foil treated with the PPE-based resin and the olefin-based silane coupling agent is laminated and hot-pressed, the copper foil and the resin become However, a local adhesion failure area called so-called swelling often occurs at the interface, which causes a reduction in the yield of the resin substrate, but this point is not mentioned. Patent Document 2 deals with copper foil having a surface roughness of 1.10 μm or less in the examples, and transmission characteristics that are practically acceptable in flexible substrate applications are obtained. No mention is made of the improvement of the characteristics of the above or the problem of local adhesion failure such as blisters.

  The present invention relates to poor adhesion in press bonding between a copper foil and a resin, particularly in press bonding with a resin of a copper foil subjected to silane coupling treatment with an olefin-based silane coupling agent on a roughened surface of the copper foil. The purpose is to eliminate.

The surface-treated copper foil of one embodiment of the present invention has a surface roughness Rzjis of the surface on the roughening treatment side of not more than 1.10 μm when measured by a contact-type roughness measuring instrument, and the roughening treatment side. The minimum autocorrelation length (Sal) of the surface is in the range of 0.20 μm to 0.85 μm, and the interface development area ratio (Sdr) of the surface on the roughening treatment side is in the range of 20% to 300%. is there.
The present inventors investigated and investigated the cause of blisters generated at the interface between the copper foil and the resin when the PPE resin and the copper foil were laminated and subjected to high-temperature press molding. As a result, the olefin-based silane coupling agent was roughened. It was found that a stress was generated on the surface, and a curl having a roughened surface side facing inward was likely to be generated. The mechanism by which stress is generated on the surface by the treatment of the olefin-based silane coupling agent is not clear, but the repulsion between the functional groups attached to the copper foil surface is weak, or they are attracted to each other and the stress is generated, causing curl. It is thought that it is. It is considered that the stress generated at this time is further increased at the time of pressing and causes poor bonding.

In order to solve this problem, copper foil having a surface property capable of dispersing the stress on the roughened surface side while maintaining the reactivity with silane to ensure resin adhesion is effective. I found something. That is, when the surface roughness Rzjis of the surface on the roughened side of the copper foil is measured to be 1.10 μm or less when measured by a contact-type roughness measuring instrument, the minimum autocorrelation length (Sal) of the surface on the roughened side is determined. The stress on the roughened surface is dispersed by setting the ratio of the interface development area (Sdr) of the surface on the roughened surface to a range of 20% to less than 300% by setting the range of 0.20 μm to 0.85 μm. Thus, it was found that the curl of the copper foil and the adhesion failure of the laminate at the time of press bonding can be eliminated.
The surface roughness Rzjis is measured using a contact type surface roughness measuring device. In one embodiment of the present invention, a ten-point average surface roughness Rzjis defined by JIS B 0601-2001 is measured using a surf coder SE1700α manufactured by Kosaka Laboratory Co., Ltd.

  The minimum autocorrelation length (Sal) is a value defined by ISO25178, and is the shortest distance in a plane where the autocorrelation of the surface shape attenuates to the correlation value s (s = 1 to s = 0.2 unless otherwise specified). The shortest distance that attenuates to the maximum) and is measured with a three-dimensional white interference microscope. Sal can be used as an index of the steepness of the surface shape caused by undulation of the surface of the foil before roughening or unevenness due to the roughening in the copper foil. That is, it can be said that the smaller the value of Sal, the higher the height difference changes over a shorter distance, and thus the steeper the surface shape. In one embodiment of the present invention, using a white light interference type surface shaper Wyko manufactured by Bruker Co., Ltd., at a magnification of 50 times, F-operator processing to remove tilt (with cylinder / tilt correction), data complementation (legacy method) , 5 times), and a high frequency cutoff (250 KHz) using a Gaussian filter is performed to measure the minimum autocorrelation length (Sal).

  The interface development area ratio (Sdr) is a value defined by ISO25178, and means a ratio of a surface area added by a surface property based on an ideal surface having a size of a measurement region, and is defined by the following equation.

  Here, x and y in the expression are plane coordinates, and z is a coordinate in the height direction. z (x, y) indicates the coordinates of a certain point, and by differentiating this, it becomes the inclination at that coordinate point. A is the plane area of the measurement region. The interface development area ratio (Sdr) should be determined by measuring and evaluating the unevenness of the copper foil surface using a three-dimensional white interference microscope, scanning electron microscope (SEM), electron beam three-dimensional roughness analyzer, etc. Can be. In an embodiment of the present invention, using a white light interference type surface shaper Wyko manufactured by Bruker Co., Ltd., at a magnification of 50 ×, F-operator processing is used to remove tilt (with cylinder / tilt correction), and data complementation (legacy method) , 5 times), and a high frequency cutoff (250 KHz) using a Gaussian filter is performed to measure the interface development area ratio Sdr. In general, Sdr tends to increase as the spatial complexity of the surface texture increases, regardless of changes in the surface roughness Sa.

When the surface roughness Rzjis of the surface of the copper foil on the roughening treatment side is 1.10 μm or less as measured by a contact-type roughness measuring device, when the PPE resin and the copper foil are laminated and hot-press-bonded, copper Swelling is less likely to occur at the interface between the foil and the resin. On the other hand, if the thickness exceeds 1.10 μm, swelling occurs at the interface between the copper foil and the resin during high-temperature press bonding, which tends to cause poor bonding.
If the minimum autocorrelation length Sal of the surface of the copper foil on the roughening treatment side is in the range of 0.20 μm to 0.85 μm, PPE resin and copper foil are laminated and used as a copper-clad laminate for high frequency In this case, it is possible to achieve both good transmission characteristics and prevention of curling and poor contact during high-temperature pressing. If Sal is less than 0.20 μm, the steepness of the surface shape becomes excessive, and when used as a copper-clad laminate for high frequencies, the skin effect tends to increase, and the transmission characteristics tend to deteriorate. On the other hand, if Sal exceeds 0.85 μm, the steepness of the surface shape is reduced, and when used as a copper-clad laminate for high frequencies, the skin effect is suppressed and there is no problem in transmission characteristics. The stress caused by the silane coupling agent is not easily dispersed, and the curl and the poor contact at the time of high-temperature pressing tend to occur.

  When the interface development area ratio Sdr of the surface on the roughening treatment side of the copper foil is in the range of 20% or more and 300% or less, when the PPE resin and the copper foil are laminated and used as a copper-clad laminate for high frequency. It is possible to achieve both good transmission characteristics and prevention of contact failure during curling and high-temperature pressing. If the Sdr is less than 20%, local stress on the surface on the roughening treatment side is difficult to be dispersed, and when performing the above-mentioned high-temperature press bonding, blisters tend to be easily generated at the interface between the copper foil and the resin. . If the Sdr exceeds 300%, the skin effect when used as a copper-clad laminate for high frequencies tends to increase, and the transmission characteristics tend to deteriorate.

  ADVANTAGE OF THE INVENTION According to this invention, the joining failure at the time of press-joining a surface-treated copper foil to a resin substrate can be eliminated, and the surface-treated copper foil excellent in the adhesiveness with a resin substrate can be provided.

It is a figure which shows the measurement part for calculating the curl value of the copper foil of an Example.

The surface-treated copper foil according to another embodiment of the present invention is the surface-treated copper foil according to the above embodiment, further provided that the interface development area ratio Sdr of the surface on the roughening treatment side is in a range of 200% or more and 260% or less. It is suitable. When the interface development area ratio (Sdr) of the surface on the roughened side of the copper foil exceeds 200%, the stress on the surface on the roughened side is more dispersed, and the copper foil tends to be less likely to curl. If it is less than 260%, the transmission characteristics when used as a copper-clad laminate for high frequency tend to be further excellent.
The surface-treated copper foil of another embodiment of the present invention may be the surface-treated copper foil of the above embodiment, wherein the surface treatment includes an olefin-based silane coupling treatment. In particular, it is more preferable that the silane coupling agent is γ-acryloxypropyltrimethoxysilane. Moreover, the surface-treated copper foil of another embodiment of the present invention has excellent adhesion to a resin substrate containing a PPE resin.

  Generally, it is known that a copper foil treated with an olefin-based silane coupling agent has good chemical affinity with a PPE-based resin substrate. It is considered that a siloxane crosslinked structure is formed on the copper foil surface, and this functions as an adhesive with the PPE-based resin. However, as described above, when a PPE-based resin and a copper foil subjected to silane coupling treatment are laminated and subjected to high-temperature press molding, an adhesion failure area called so-called blister is generated at the interface between the copper foil and the resin, and the adhesion failure occurs. Tends to occur. The copper foil of the embodiment of the present invention is excellent in adhesion to a resin substrate containing a PPE resin, even if the copper foil is silane-coupled with an olefin-based silane coupling agent, particularly acrylic silane.

(Manufacture of copper foil)
The copper foil used in the present invention may be either an electrolytic copper foil or a rolled copper foil. Usually, electrolytic copper foil is widely used for printed wiring boards. In this case, an electrolytic deposition start surface (S surface) on the drum surface side in the foil making process, or an electrolytic deposition end surface (M surface) on the non-drum surface side, or a heat-resistant treatment layer described later. And an olefin-based silane coupling agent layer may be formed. Normally, the M surface is used as an adhesive surface. However, the surface-treated copper foil of the present invention has an interface development area ratio (Sdr) of the surface on the roughening treatment side by the surface treatment including the roughening treatment on either surface. Is in the range of 20% or more and 300% or less, the adhesiveness to the resin is excellent, and the transmission characteristics when used as a copper-clad laminate for high frequencies are excellent.

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

By adding a metal such as iron (Fe) and tungsten (W) to the electrolytic bath in addition to copper sulfate and palladium sulfate (Pd), the stress caused by the silane coupling agent can be dispersed. Surface shape can be formed. Normally, the copper concentration is 15 to 25 g / L, the sulfuric acid concentration is 130 to 180 g / L, the liquid temperature is 20 to 30 ° C., the current density is 30 to 40 A / dm ² , and the processing time is 5 to 30 seconds. Analysis is performed.

(Formation of nickel layer, zinc layer and chromate treatment layer)
In the present invention, it is preferable to further form a nickel layer and a zinc layer on the roughened surface in this order. When the thin copper foil and the resin substrate are thermocompressed, the zinc layer prevents the deterioration of the substrate resin and the surface oxidation of the thin copper foil due to the reaction with the thin copper foil substrate resin, thereby increasing the bonding strength with the substrate. , Functions as a heat-resistant layer. Further, the nickel layer prevents the zinc of the zinc layer from thermally diffusing to the copper foil (electrolytic copper plating layer) side during the thermocompression bonding to the resin substrate, and thus the zinc for effectively exhibiting the above-described function of the zinc layer. Serves as an underlayer for the layer.

The nickel layer and the zinc layer can be formed by applying a known electrolytic plating method or electroless plating method. Further, the nickel layer may be formed of pure nickel or a phosphorus-containing nickel alloy.
Further, it is preferable to further perform a chromate treatment on the surface of the zinc layer because an antioxidant layer is formed on the surface. The chromate treatment to be applied may be in accordance with a known method, for example, a method disclosed in Japanese Patent Application Laid-Open No. 60-86894. By adhering about 0.01 to 0.3 mg / dm ² of chromium oxide and its hydrate in terms of the amount of chromium, the copper foil can have excellent rust-preventive ability.

(Silane treatment)
Next, the copper foil subjected to the surface treatment as described above is coated with an olefin-based silane coupling agent having an excellent affinity for the PPE-based resin to form a thin film thereof. Adhesion amount of the silane coupling agent is preferably a 0.25~0.40mg / dm ^2, may be 0.20~0.50 mg / dm ² 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 is 0.001 to 10% by mass, preferably 0.01 to 6% by mass. If the amount is less than 0.001% by mass, the effect of improving adhesion tends to decrease, and if it exceeds 10% by mass, the effect tends to be saturated and the solubility tends to deteriorate.

  Examples of the olefin silane coupling agent include vinyl silane, acrylic silane, and methacryl silane. The vinyl silane is vinyltrichlorosilane, vinyltrialkoxysilane, vinyldialkoxyalkylsilane, and the like. For example, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, vinyldimethoxymethylsilane, vinyl And diethoxymethylsilane. Examples of the acrylic silane include γ-acryloxypropyltrimethoxysilane. Examples of the methacrylic silane include γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, and γ-methacryloxypropyltriethoxysilane. In particular, acrylic silane or the like can be used.

After applying the olefin-based silane coupling agent to the copper foil, the treated copper foil is air-dried or heat-dried. The effect of the present invention can be sufficiently exhibited as long as water evaporates, but drying at 50 to 180 ° C. is preferable because the reaction between the silane coupling agent and the copper foil is promoted. If necessary, other additives such as a silane coupling agent, a pH adjuster, and a buffer can be appropriately added and blended.
The copper foil of the present invention may be formed with a siloxane coating as a pretreatment before the silane treatment. By forming the siloxane coating, the acid resistance of the copper foil can be further improved, and the adhesive strength with the insulating resin can be improved. The method of forming a siloxane coating is to dilute a silicate solution or a silicon compound such as tetraalkoxysilane with a solvent such as water, methanol, ethanol, acetone, ethyl acetate or toluene so as to be 0.001 to 20% by weight. Then, it may be applied to the copper foil by any method such as spraying with a spray, coating with a coater, dipping, and pouring.

(Manufacture of copper-clad laminates)
A copper foil surface (roughened layer surface) of a thin copper foil is placed on a surface of an electrically insulating substrate in which a resin containing a polyphenylene ether resin, for example, a polyphenylene ether resin and a polystyrene resin are mixed, and heated and pressed. To produce a copper-clad laminate.

  Next, the present invention will be specifically described based on examples. These examples are merely examples of preferred embodiments, and the embodiments can take various forms without departing from the spirit of the present invention.

(Manufacture of electrolytic copper foil)
In order to produce the copper foils of Examples 1 to 12 and Comparative Examples 1 to 13, an electrolytic solution having the following composition was prepared, and under the following conditions, the anode was a noble metal oxide-coated titanium electrode, and the cathode was titanium. An electrolytic copper foil having a thickness of 18 μm was produced at a current density of 50 to 100 A / dm ² by using a rotary drum made of a resin.
Copper: 70-130 g / L
Sulfuric acid: 80-140 g / L
Additives: Sodium 3-mercapto-1-propanesulfonate = 1 to 10 ppm
Hydroxyethyl cellulose = 1 to 100 ppm
Low molecular weight glue (molecular weight 3,000) = 1 to 50 ppm
Chloride ion concentration = 10 to 50 ppm
Temperature: 50-60 ° C

(Roughening treatment)
Next, the copper foils of Examples 1 to 12 were subjected to the first roughening treatment 1 and the next roughening treatment 2 under the following conditions.

(Roughening treatment 1)
Copper sulfate: 15 to 25 g-Cu / L as copper concentration
Sulfuric acid concentration: 130-180 g / L
Palladium compound: 0.01 to 0.05 g-Pd / L as palladium concentration
Iron compound: 0.1 to 0.3 g-Fe / L as iron concentration
Tungsten compound: 0.5 to 1.5 g-W / L as tungsten concentration
Liquid temperature: 20-30 ° C
Current density: 30 to 40 A / dm ²

(Roughening treatment 2)
Copper sulfate: 40-70 g-Cu / L as copper concentration
Sulfuric acid concentration: 80 to 120 g / L
Liquid temperature: 20-30 ° C
Current density: 1.5 to 4 A / dm ²
On the other hand, the copper foils of Comparative Examples 1 to 4 were subjected to rough plating based on the example of Patent Document 2, and Comparative Examples 5 to 8 were subjected to rough plating based on the example of Patent Document 3. Further, for Comparative Examples 9 to 13, the following roughening treatment 3 and the above-described roughening treatment 2, and for Comparative Examples 14 to 17, the following roughening treatment 4 and the roughening treatment 2, No. 21 was performed by combining the following roughening treatments 5 and 2.

(Roughening treatment 3)
Copper sulfate: 15 to 25 g-Cu / L as copper concentration
Sulfuric acid concentration: 130-180 g / L
Molybdenum compound: 0.1 to 0.5 g-Mo / L as molybdenum concentration
Iron compound: 0.1 to 0.3 g-Fe / L as iron concentration
Liquid temperature: 20-60 ° C
Current density: 20 to 50 A / dm ²

(Roughening treatment 4)
Copper sulfate: 15 to 25 g-Cu / L as copper concentration
Sulfuric acid concentration: 130-180 g / L
Iron compound: 0.1 to 0.3 g-Fe / L as iron concentration
Liquid temperature: 20-60 ° C
Current density: 20 to 50 A / dm ²

(Roughening treatment 5)
Copper sulfate: 15 to 25 g-Cu / L as copper concentration
Sulfuric acid concentration: 130-180 g / L
Tungsten compound: 0.5 to 1.5 g-W / L as tungsten concentration
Liquid temperature: 20-60 ° C
Current density: 20 to 50 A / dm ²

(Metal plating)
Next, for the copper foils of Examples 1 to 12 and Comparative Examples 1 to 21, metal plating under the following conditions was performed in the order of nickel plating, zinc plating, and chromic acid plating.

(Nickel plating)
The primary treatment layer was applied under the following plating bath and plating conditions.
Nickel sulfate hexahydrate: 200-300 g / L
Nickel chloride hexahydrate: 30-60 g / L
Boric acid: 20-40 g / L
Liquid temperature: 40-60 ° C
Current density: 0.1 to 10 A / dm ²
Energizing time: 1 second to 2 minutes

(Zinc plating)
The secondary treatment layer was applied under the following plating bath and plating conditions.
Zinc sulfate heptahydrate: 1 to 30 g / L
Sodium hydroxide: 10 to 150 g / L
Liquid temperature: 10-30 ° C
Current density: 0.1 to 10 A / dm ²
Energizing time: 1 second to 2 minutes

(Chromic plating)
After each metal plating layer treatment, a chromate treatment was performed under the following conditions.
Chromic anhydride: 0.1 to 10 g / L
Liquid temperature: 20-40 ° C
Current density: 0.1 to ^{2 A} / dm ²
Energizing time: 1 second to 2 minutes

  Next, with respect to the copper foils of Examples 1 to 12 and Comparative Examples 1 to 21, 1 vol. % Aqueous solution was applied to the surface-treated copper foil at room temperature. More specifically, an aqueous solution of a silane coupling agent was uniformly flowed for 1 minute in a state where the copper foil was slanted, and then the solution was drained with a roll and dried.

  For the copper foils of Examples 1 to 12 and Comparative Examples 1 to 21 having been subjected to the above surface treatment, the interface development area ratio Sdr, the minimum autocorrelation length Sal, and the surface roughness Rz were measured by the following method. Then, the curl level was evaluated.

(Measurement of interface development area ratio Sdr and minimum autocorrelation length Sal)
Using a white light interference type surface shape measuring device Wyko manufactured by Bruker Co., Ltd. at 50 times magnification, F-operator processing to remove tilt (cylinder / tilt correction), data complement (legacy method, 5 repetitions), Gaussian A high-frequency cutoff (250 KHz) was performed using a filter to measure the interface development area ratio Sdr and the minimum autocorrelation length Sal on the roughened surface side of the surface-treated copper foil. The number of measurement points was five, and the average value was used as the measurement result. The results are shown in Table 2.

(Measurement of surface roughness Rz)
A 10-point average roughness Rz was measured using a surf coder SE1700 manufactured by Kosaka Laboratory Co., Ltd. as a contact-type surface roughness measuring device. The results are shown in Table 2.

(Evaluation of curl level)
As shown in FIG. 1, the copper foil 10 that has been subjected to the silane coupling treatment is cut into a rectangle of 10 cm in length and 5 cm in width, and the roughened surface (M surface) of the copper foil 10 is placed on a horizontal table. And a stainless steel straight ruler (C type JIS first grade 30 cm) 20 of KOKUYO TZ-1343 (trade name) was put as a weight so that the left end protruded 2 cm in width. Then, the surface on which the copper foil 10 was allowed to stand at a total of three points, that is, a central portion (position A in the figure) in the vertical direction of the copper foil 10 and portions 2 cm above and below it (positions B and C in the figure). The curl value was measured by measuring the height [mm] of the rise of the edge from the end and calculating the average value of three points.

The degree of curl obtained was evaluated according to the following criteria. That is, if the curl value is less than 0.5 mm, it is evaluated as “◎”, if it is 0.5 mm or more and less than 1.5 mm, it is evaluated as “Good”, and if it becomes 1.5 mm or more, it is evaluated as “X”. Are shown in Table 2.
Next, in order to evaluate blisters and transmission characteristics at the time of thermocompression bonding to a resin substrate, the copper foils of Examples 1 to 12 and Comparative Examples 1 to 21 which were subjected to the above-described surface treatment were subjected to the following method. Then, the blister level and the transmission characteristics were evaluated.

(Press bonding to resin substrate)
A polyphenylene ether resin and a polystyrene resin were mixed at a specific ratio to prepare a 0.2 mm-thick plate-shaped resin base material. The surface to be coated with the silane coupling agent of the surface-treated copper foil and the resin substrate are overlapped, and a hot press molding method (press, using a mini test press (trade name, manufactured by Toyo Seiki Seisaku-sho, Ltd.)) A temperature = 200 ° C., a pressing pressure = 3.0 MPa) was used to produce a copper-clad laminate composed of a surface-treated copper foil and a resin substrate, and used as a test piece.

(Measurement of adhesion strength)
The adhesion strength was determined by pressing the insulating substrate and copper foil using a tensilon tester (manufactured by A & D Corporation), etching the test piece into a 10 mm wide circuit pattern, and turning the circuit pattern in the 90 degree direction. Was measured at a speed of 50 mm / min. The number of measurement samples was 5, and the average value thereof was used as the measurement result.
The level of adhesion strength was evaluated according to the following criteria. In other words, those with a peel strength of 0.7 kN / m or more were evaluated as excellent (」), those with a peel strength of 0.5 kN / m or more and less than 0.7 kN / m were evaluated as good (「), and those with a peel strength of 0.4 kN / m or more Tables 2 each show "x", indicating that the sample was less than 0.5 kN / m.

(Evaluation of blister level)
After laminating the above-mentioned resin base material and copper foil of 100 mm × 100 mm (1 dm ² ) by hot pressing under the above conditions, the copper foil is etched using a cupric chloride solution, and the copper foil is dissolved and removed separately. The polyphenylene ether-based resin base material was laminated and hot-pressed to produce a test piece. The test piece was subjected to reflow heating at a top temperature of 260 ° C. through a reflow furnace, and the presence or absence of blisters generated on the cooled test piece was observed.
The blister level was evaluated according to the following criteria. That is, the number of blisters generated was 0 / dm ² as excellent (「), 1-2 / dm ² as good (○), 3 / dm ² or more as bad (不可). And “×” are shown in Table 2.

(Transmission characteristics)
After laminating the surface-treated copper foil on the resin substrate by hot press molding, a sample for measuring the transmission characteristics was prepared, and the transmission loss in the high frequency band was measured. To evaluate the transmission characteristics, a known stripline resonator method (microstrip structure: dielectric thickness: 50 μm, conductor length: 1.0 mm, conductor thickness: 18 μm, conductor circuit width: 120 μm) suitable for measurement in the 1 to 25 GHz band, Transmission loss (dB / 100 mm) at a frequency of 10 GHz was measured using a method of measuring the S21 parameter with a characteristic impedance of 50Ω and no coverlay film. As the transmission loss increases, the negative absolute value increases. The number of measurement samples was 5, and the average value thereof was used as the measurement result.
Based on the obtained transmission loss, the transmission characteristics were evaluated according to the following criteria. In other words, Table 2 shows that the absolute value of the transmission loss was less than 16 dB as "◎", that of 16 dB or more and less than 20 dB as "Good", and that of 20 dB or more as "X". Indicated.

(Comprehensive evaluation of copper foil properties)
In consideration of the above-described levels of adhesion strength, curl, blister, and transmission characteristics, a comprehensive evaluation of the copper foil was performed according to the following criteria. That is, there is no "x" and "S" if all items are "◎", "A" if there are two or three "◎", and "B" if there is one "◎". And On the other hand, if there is “×”, the number is “C” if the number is 1, “D” if it is 2, “E” if it is 3, and if all items are “×”. This is shown in Table 2 as “F”.

  As can be seen from Table 2, in Examples 1 to 4, both the curl level and the blister level were very good, and the transmission characteristics were also good. Next, in Examples 5 to 8, since the Sdr value was slightly smaller than that in Example 1, the curl level and blister level were slightly inferior, but the quality was not a problem, and the transmission characteristics were good. Further, in Examples 9 to 12, since the Sdr value is slightly larger than that in Example 1, the curl level and the blister level are good, and the transmission characteristics are slightly inferior because the skin effect of the current is large. There was no problem.

  On the other hand, in Comparative Examples 1 to 4, since the Sdr value was 20% or less, both the curl level and the blister level failed in terms of quality. In Comparative Examples 5 to 8, since the Sdr value exceeded 300%, there was no problem with the curl level and blister level, but the skin effect was too large and the quality was unacceptable. In Comparative Examples 9 to 13, since the roughness Rz of the roughened surface exceeded 1.10 μm and was excessive, the curl level and blister level were rejected regardless of the value of Sdr. Since the skin effect became too large, the transmission loss was also rejected. In Comparative Examples 14 to 17, since the Sal value was too small at less than 0.20 μm, the skin effect was increased and the transmission characteristics were unacceptable. Further, in Comparative Examples 18 to 21, the curl level and blister level were rejected because the Sal value was excessively larger than 0.85 μm.

  ADVANTAGE OF THE INVENTION According to this invention, the joining defect at the time of press-joining the surface-treated copper foil with the resin substrate can be eliminated, the surface-treated copper foil excellent in the adhesiveness with the resin substrate, and the copper excellent in the transmission characteristics. It can provide a laminated board and has high industrial applicability.

10 Copper foil 20 Ruler

Claims (7)

The ten-point average surface roughness Rzjis defined by JISB0601-2001 on the surface on the roughening treatment side is 0. 19 μm or more and 1.10 μm or less, and the minimum autocorrelation length (Sal) of the surface on the roughened side is in a range of 0.20 μm or more and 0.85 μm or less, and the surface on the roughened side. A surface-treated copper foil having an interface development area ratio (Sdr) of more than 100% to 300% or less.   The surface-treated copper foil according to claim 1, wherein the interface development area ratio (Sdr) is in a range of 200% or more and 260% or less.   The surface-treated copper foil according to claim 1, wherein a silane coupling agent layer is formed on the surface-treated copper foil using an olefin-based silane coupling agent.   The surface-treated copper foil according to claim 3, wherein the olefin-based silane coupling agent is γ-acryloxypropyltrimethoxysilane. Technology of peel strength between the resin substrate containing polyphenylene ether resin is at 0.5 kN / m or more, the peeling strength between the surface-treated copper foil and the resin substrate after pressing, the circuit of 10mm wide test pieces The method according to any one of claims 1 to 4, wherein the pattern is etched, and the circuit pattern is measured by pulling the circuit pattern in a 90-degree direction at a speed of 50 mm / min using a tensilon tester (manufactured by A & D Corporation). The surface-treated copper foil according to claim 1.   In a surface-treated copper foil having an olefin-based silane coupling agent layer on the surface, the surface-treated copper foil is cut into a rectangle of 10 cm (length) × 5 cm (width), and the roughened surface (M surface) of the surface-treated copper foil is turned upside down. Place it on a horizontal table and place a stainless steel straightedge so that the left end protrudes by 2 cm. The surface-treated copper foil is a total of three points: the central part in the vertical direction of the surface-treated copper foil and two cm above and below it. The curl value obtained by measuring the height [mm] of the rise of the end from the surface on which the sample is placed and calculating the average value of the rise heights at the three points is less than 0.5 mm. The surface-treated copper foil according to any one of claims 1 to 5, characterized in that: A surface-treated copper foil having an olefin-based silane coupling agent layer on its surface,
The number of blisters measured in a copper-clad laminate obtained by laminating a mixed resin base material having a thickness of 0.2 mm having a polyphenylene ether resin and the olefin-based silane coupling agent layer side of the surface-treated copper foil. Is zero,
In the measurement, the copper-clad laminate was cut into 100 mm x 100 mm, and the surface-treated copper foil was etched and dissolved and removed with a cupric chloride solution, and another polyphenylene ether-based resin base material was superimposed thereon and hot-pressed. Forming a test piece, performing reflow heating by passing the test piece through a reflow furnace at a top temperature of 260 ° C., and measuring the number of blisters generated on the test piece after cooling. The surface-treated copper foil according to any one of claims 1 to 6.

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