TWI749123B - Surface treatment copper foil and copper clad laminate - Google Patents

Abstract

The present invention is a surface-treated copper foil, which is on at least one side of the copper foil, and the surface-treated copper foil is laminated with a roughening treatment layer, an anti-rust treatment layer and a silane coupling layer in this order based on the aforementioned copper foil, and The value of the spread area ratio Sdr of the interface, which is a composite parameter of the three-dimensional surface properties measured from the surface of the aforementioned silane coupling layer, is in the range of 8 to 140%.

Description

Surface treatment copper foil and copper clad laminate

The present invention relates to a surface-treated copper foil and a copper-clad laminate board, and more particularly to a surface-treated copper foil and a copper-clad laminate board suitable for use as a component constituting a printed wiring board, wherein the printed wiring board is above several gigahertz ( When used in the high frequency band of GHz), the transmission loss of high-frequency electrical signals is small, and it has excellent reflow heat resistance.

Due to the increase of cloud services and the development of communication equipment, the amount of data communication continues to increase. Along with this, in order to increase the communication speed, devices such as routers, servers, and mobile phone base station antennas have been developed in recent years to cope with high frequencies exceeding 20 GHz. Regarding the printed wiring boards of such high-frequency equipment, from the viewpoint of high-frequency transmission, resins such as modified polyphenylene ether resins or liquid crystal polymers with material characteristics of low dielectric constant and low dielectric loss tangent are used The base material, in addition, as a material for forming the circuit wiring through which the signal flows, copper foil with less transmission loss is required.

In the high frequency band exceeding a few GHz, the current flowing in the circuit wiring is concentrated on the surface of the conductor due to the skin effect. Therefore, in order to improve the adhesion to the resin and use the copper foil with a purely increased surface roughness, there is copper The problem of increased transmission loss on the foil surface. In order to reduce the transmission loss, it is usually better to use copper foil with reduced surface roughness.

As for high-frequency printed wiring boards, multi-layers have been developed along with higher functionality. In most cases, high-multilayer printed wiring boards with more than 30 layers are used. In multilayer printed wiring boards, delamination between layers is prone to occur under thermal load. In particular, in the reflow soldering step performed when electronic parts are mounted on the surface of a printed wiring board, there is a tendency that the printed wiring board is exposed to a high temperature heat load accompanied by a rapid temperature rise in a short period of time, so moisture or organic matter in the resin It evaporates at once and expands in volume, so foaming is likely to occur, and as a result, the risk of defective interlayer peeling increases. Therefore, from the viewpoint of reliability, good adhesion during reflow soldering (hereinafter referred to as "reflow heat resistance") is valued.

As a means for improving the peeling strength of the copper foil to the resin substrate and reducing the transmission loss in the high frequency band, for example, Patent Document 1 discloses a copper foil for a high frequency printed wiring board, which is characterized by: At least one surface has a roughening treatment layer composed of spherical fine roughened particles with a diameter of 0.05~1.0 µm, and the roughening treatment layer has at least one of molybdenum, nickel, tungsten, phosphorus, cobalt, and germanium. A heat-resistant anti-rust layer composed of more than one type, and has a chromate film layer on the heat-resistant anti-rust layer, and a silane coupling agent layer on the chromate film layer. In addition, Patent Document 1 discloses that by reducing the roughening particles formed on the copper foil, the peeling strength of the copper foil to the resin substrate is stronger, and the circuit bottom line of the copper foil after the circuit pattern is formed by etching ( The bottom line) has high linearity, which can reduce transmission loss. However, Patent Document 1 does not focus on the reflow heat resistance as the adhesiveness during reflow soldering. In addition, it has not studied the effect of the specific surface roughening shape and the skin effect on the reduction of the transmission characteristics.

In addition, Patent Document 2 discloses a surface-treated copper foil, which is characterized in that the surface roughness (Rzjis) of the bonding surface bonded to the insulating resin substrate is 2.5 µm or less, and the two-dimensional surface area is measured by the laser method. three-dimensional surface area (a) measured at an area of 6550 μm ² μm ² surface area of the two-dimensional ratio [(a) / (6550) ] of the value, i.e., the surface area ratio (B) is 1.2 to 2.5. In addition, Patent Document 2 discloses that if the surface-treated copper foil is used, the edge of the wiring circuit formed on the printed wiring board can obtain good linearity, not only has good adhesion with the insulating resin substrate, but also has chemical resistance. , Moisture resistance, etc. are also good. Regarding the transmission loss or characteristic impedance of high-frequency signals in the GHz band, electrical characteristics close to the design values can be achieved. However, although Patent Document 2 adopts a configuration in which the surface roughness (Rzjis) and the surface area ratio (B) are respectively limited to appropriate ranges, it is not possible to specify accurate surface properties when only the surface roughness and the surface area ratio are limited. For example, Figure 4(a) and Figure 4(b) conceptually show two surface states with the same surface area but different surface roughness from a geometrical point of view, but the comparison of the two surface states also shows that, The dimensions of the height or width of the mountain are very different, and it is difficult to be regarded as the same as the transmission characteristics or the adhesion with the resin. In addition, Patent Document 2 does not focus on the heat resistance of reflow, and has not studied the specific surface roughening shape and the effect of the skin effect on the reduction of transmission characteristics.

Patent Document 3 discloses a roughening treatment copper foil, which has a roughening treatment surface formed by precipitating fine copper particles on the surface of the copper foil, and the roughening treatment copper foil is characterized in that the roughening treatment surface includes Fine copper particles in the shape of protrusions with a head angle of 85° or less. In addition, Patent Document 3 discloses that the roughening treatment of copper foil is effective for liquid crystal polymer, polyphenylene oxide resin (PPO), polyphenylene ether resin (PPE), cycloolefin polymer ( COP) and other resins with high heat resistance and excellent high frequency characteristics have sufficient adhesion and can reduce transmission characteristics. However, Patent Document 3 only specifies the angle of the crown of the fine copper particles constituting the roughened surface, and does not impose any limitation on the shape other than the crown. In addition, although Patent Document 3 uses the L* value, a* value, and b* value of the L*a*b* color system to indirectly quantitatively roughen the shape, but L*, a*, and b* are the chromaticity parameter. Therefore, when a colored electroplated film is formed on the surface of copper foil due to Ni, Co, Cr, etc., or when the surface of the copper foil is oxidized and discolored, it will greatly affect these values. Therefore, it is necessary to accurately grasp and It is technically very difficult to manage the surface shape of the roughening treatment.

In addition, Patent Document 4 discloses a surface-treated copper foil in which a surface-treated layer is formed on at least one surface, the surface-treated layer includes a roughened layer, and the total amount of Co, Ni, and Fe in the surface-treated layer is adhered The amount is 300 µg/dm ² or less, the surface treatment layer has a Zn metal layer or an alloy treatment layer containing Zn, and the ratio of the three-dimensional surface area to the two-dimensional surface area measured by a laser microscope on the surface of the surface treatment layer is 1.0 ~1.9, and the surface roughness Rzjis of at least one surface is below 2.2 µm. In addition, Patent Document 4 discloses that in the surface-treated copper foil, the total adhesion amount of the metal (Co, Ni, Fe) exhibiting ferromagnetism at room temperature in the surface-treated layer is controlled to a predetermined amount or less, and is contained in Zn, which does not exhibit ferromagnetism at room temperature, reduces high-frequency transmission loss, and controls the surface roughness Rz and the ratio of the two-dimensional surface area to the three-dimensional surface area that more accurately represents the contact area with the resin (dielectric) The proper range can improve the transmission characteristics. However, in Patent Document 4, it is very difficult to specify the surface shape or characteristics of the surface-treated copper foil by the surface area ratio and Rz as described above, and it is impossible to clearly define the surface that significantly affects the transmission characteristics. In addition, usually in the steps of making printed wiring boards, an etching step or a reflow soldering step for forming a circuit is required, which requires chemical resistance, reflow heat resistance, and the like. On the other hand, as in the surface-treated copper foil described in Patent Document 4, when the transmission characteristics are improved by reducing the ferromagnetic metal in the surface-treated layer, the surface-treated layer containing Zn is used in the chlorination of etching. Copper, ferric chloride, sulfuric acid-hydrogen peroxide water and other etching solutions are easily dissolved. Therefore, over-etching is likely to occur during etching, and the linearity of the circuit is poor. In the worst case, it may be peeled off from the resin after the circuit pattern is made. In addition, Zn is easily diffused in the Cu layer due to heating. Therefore, in the reflow heat resistance test described later, peeling failures easily occur between the copper and the resin. That is, the transmission characteristics are excellent, but defects in the manufacturing steps of the printed wiring board are prone to occur, and there is also a problem that it cannot be manufactured stably in the industry. [Prior technical literature] [Patent literature]

Patent Document 1: Japanese Patent Laid-Open No. 2006-210689 Patent Document 2: Japanese Patent Laid-Open No. 2008-285751 Patent Document 3: Japanese Patent Laid-Open No. 2010-236058 Patent Document 4: Japanese Patent Laid-Open No. 2015-105440 Bulletin

[The problem to be solved by the invention]

As mentioned above, as a copper foil for high-frequency printed wiring boards with less transmission loss, copper foil with a surface shape with a smaller surface roughness is usually required. However, if the copper foil becomes smooth, it will adhere to the resin. Problems such as reduced performance and reduced heat resistance of reflow. In addition, in order to improve the adhesion to the resin, the surface of the copper foil is treated with a silane coupling agent to improve the chemical adhesion with the resin substrate. However, in order to improve the chemical adhesion between the silane coupling agent and the resin substrate, it is necessary to make the resin To a certain extent, it has a very polar substituent.

However, resins with a low dielectric constant or dielectric loss tangent do not have a substituent with a large polarity, or even with a substituent with a large polarity, its content is small, so the chemical adhesion with the silane coupling agent is reduced, and it is difficult to ensure Adequate adhesion between copper foil and resin substrate. On the other hand, if the surface roughness of the copper foil is increased in order to improve adhesion or reflow heat resistance, the problem of reduced transmission characteristics will occur. High-frequency substrates require copper foils that have such trade-off characteristics, that is, copper foils that have sufficient adhesion strength and reflow heat resistance, and excellent transmission characteristics.

As described above, when used as, for example, copper foil for high-frequency printed wiring boards used in high frequency bands exceeding several GHz, it is difficult to provide any of the surface-treated copper foils described in Patent Documents 1 to 4 A higher level of printed wiring boards that fully meets both transmission characteristics and reflow heat resistance requires further improvement of the surface properties of the surface-treated copper foil.

The object of the present invention is to provide a surface-treated copper foil and a copper-clad laminate. The surface-treated copper foil can be manufactured even if it is used as, for example, copper foil for high-frequency printed wiring boards used in high frequency bands exceeding several GHz. A printed wiring board with low transmission loss of high-frequency electrical signals and excellent reflow heat resistance. [Technical means to solve the problem]

The inventors of the present invention aimed at the surface shape of surface-treated copper foil with excellent reflow heat resistance and reduced transmission loss, and used a method different from the previous method to control the surface shape of the roughened layer, thereby, even if used as, for example, , Copper foil for high-frequency printed wiring boards used in high frequency bands exceeding a few GHz has also successfully provided printed wiring boards that fully satisfy both transmission characteristics and reflow heat resistance at a high level. Specifically, the following knowledge was obtained: In order to appropriately control the surface properties of the roughened layer, the surface properties of the roughened layer were strictly controlled by using an optical interference microscope, and the appropriateness of the surface properties was different from the previous one. The complex parameters of the novel three-dimensional surface properties can stably provide surface-treated copper foils that exhibit excellent characteristics.

That is, the main structure of the present invention is as follows. (1) A surface-treated copper foil, which is on at least one side of the copper foil, and the surface-treated copper foil is laminated with a roughening treatment layer, an anti-rust treatment layer, and a silane coupling layer in sequence based on the aforementioned copper foil, and It is characterized in that the value of the spread area ratio Sdr of the interface, which is a composite parameter of the three-dimensional surface properties measured from the surface of the aforementioned silane coupling layer, is in the range of 8 to 140%. (2) The surface-treated copper foil as described in (1) above, characterized in that the root mean square surface gradient Sdq, which is a composite parameter of the three-dimensional surface properties measured from the surface of the aforementioned silane coupling layer, has a value of 25 to 70° The scope. (3) The surface-treated copper foil as described in (1) or (2) above, wherein the value of the aspect ratio Str of the surface texture as the spatial parameter of the three-dimensional surface texture measured from the surface of the aforementioned silane coupling layer is 0.25~1 . (4) The surface-treated copper foil described in any one of (1) to (3) above, characterized in that: the ten-point average roughness Rzjis measured from the surface of the aforementioned silane coupling layer is in the range of 0.9 to 1.5 µm . (5) The surface-treated copper foil described in any one of (1) to (4) above, characterized in that the metal other than copper in the roughening treatment layer and the anti-rust treatment layer and the oxidation of the metal The total content of substances is 0.15~0.50 mg/dm ² in terms of metal elements. (6) The surface-treated copper foil as described in any one of (1) to (5) above, characterized in that the contents of Ni and Zn in the roughening treatment layer and the antirust treatment layer are 0.05~ 0.30 mg/dm ² . (7) The surface-treated copper foil described in any one of (1) to (6) above, characterized in that: the copper foil is an electrolytic copper foil, and only the M surface of the electrolytic copper foil has the roughening treatment Floor. (8) A copper-clad laminate, characterized by having the surface-treated copper foil described in any one of (1) to (7) above, and the silane coupling layer laminated on the surface-treated copper foil Resin, which has a dielectric constant of 3.5 or less and a dielectric loss tangent of 0.006 or less at a frequency of 10 GHz. [Effects of the invention]

According to the present invention, there is provided a surface-treated copper foil and a copper-clad laminate, wherein the above-mentioned surface-treated copper foil is a type of copper foil having a roughening treatment layer and an anti-rust treatment layer sequentially laminated on at least one side of the copper foil based on the aforementioned copper foil The surface treatment copper foil of the silane coupling layer and the silane coupling layer can be manufactured stably by using the spread area ratio Sdr of the interface as the composite parameter of the three-dimensional surface properties measured from the surface of the silane coupling layer to be in the range of 8~140% Surface-treated copper foil with a roughened surface shape that is difficult to control by previously used indicators (parameters) such as surface area or surface roughness. Copper foil for high-frequency printed wiring boards can also be used to produce printed wiring boards with low transmission loss of high-frequency electrical signals and excellent reflow heat resistance. In addition, by using a three-dimensional light interference microscope, it is possible to appropriately control the sharpness (surface gradient), the development area, etc. of the unevenness of the surface of the surface-treated copper foil.

Next, the embodiments of the present invention will be described in detail below. The surface-treated copper foil of the present invention is on at least one side of the copper foil, and a roughening treatment layer, an anti-rust treatment layer and a silane coupling layer are sequentially laminated based on the copper foil. That is, a roughening treatment layer is formed on at least one side of the copper foil, an antirust treatment layer is formed on the roughening treatment layer, and a silane coupling layer is formed on the antirust treatment layer. In addition, as the surface properties of the silane coupling layer corresponding to the outermost layer of this layered structure, the value of the spread area ratio Sdr of the interface, which is a composite parameter of the three-dimensional surface properties measured from the surface of the silane coupling layer, is controlled to be 8~140 % Range.

In the analysis of the surface properties of the surface-treated copper foil of the present invention, a three-dimensional light interference microscope can be used. Light interference is a phenomenon that occurs when there is a difference in the distance (optical path) of light from the surface of the object to a certain point. The optical interferometer uses this phenomenon to measure the unevenness of the surface of the object. As a characteristic of the three-dimensional light interference microscope, the resolution in the Z direction (height direction) is about 0.1 nm, which can be measured with very good sensitivity; even if the measurement magnification is changed, the resolution in the Z direction does not change. On the other hand, for example, the confocal laser microscope, which has been widely used before, implements biaxial scanning in the X and Y directions, so the resolution in the Z direction is as large as 10 nm~300 nm, which is not suitable for identification Surface treatment copper foil has very fine surface properties. In addition, in this confocal method, the resolution in the Z direction greatly changes depending on the measurement magnification, so it is not suitable for quantitatively expressing the roughened shape.

Therefore, the inventors of the present invention conducted studies using a three-dimensional light interference microscope in order to obtain a copper foil with low transmission loss and good reflow heat resistance. As a result, by strictly controlling the value of the spread area ratio Sdr as a composite parameter of the three-dimensional surface properties measured from the surface of the silane coupling layer, a surface treatment with less transmission loss and good reflow heat resistance can be obtained. Copper foil.

Sdr represents the spread area ratio of the interface (surface) of the roughened layer. Furthermore, in the present invention, the value of Sdr is measured from the surface of the silane coupling layer which is the outermost layer of the surface-treated copper foil. The roughening treatment layer is further laminated to form an anti-rust treatment layer and the surface shape of the silane coupling layer after the silane coupling layer is almost unchanged. Therefore, in the present invention, the value of Sdr measured from the surface of the silane coupling layer and the value of Sdr measured from the surface of the roughening treatment layer are regarded as the same and specified.

Here, Sdr represents the spread area ratio of the interface, which is expressed by the following formula. [Numerical formula 1]

The characteristic of Sdr is that the shape of the surface with similar arithmetic mean height Sa can be distinguished. The arithmetic average height Sa represents the average value of the absolute value of the height difference of each point with respect to the average surface of the surface. Therefore, although it is suitable for judging the information of the average height of the concavity and convexity, it cannot judge the complexity of the concavity and convexity of the surface shape.

In contrast, the value of Sdr is affected by both the amplitude and the interval of the unevenness of the surface shape. The larger the amplitude and the narrower the interval, the higher the value is displayed. Generally, when Sdr is low, Sa is usually low in most cases, and when Sdr is large, Sa tends to increase. However, Sa is a parameter representing height and therefore does not depend on the amplitude or interval of unevenness. That is, Sdr can recognize the complexity of the unevenness of the surface shape that cannot be represented by Sa. When the value of Sdr is small, it has a surface shape that is close to flat. On the other hand, when the value of Sdr is large, it has a surface shape with more unevenness.

The inventors tried to produce multiple surface-treated copper foils with different values of Sdr, and conducted painstaking research on the relationship between transmission characteristics and reflow heat resistance. By limiting the value of Sdr to between 8 and 140% Range, and the complexity of the unevenness of the roughened particles existing on the surface of the roughened layer is appropriately controlled. As a result, the transmission characteristics and reflow heat resistance are excellent. If the value of Sdr is less than 8%, a tendency to reduce the heat resistance of reflow can be observed. It is presumed that the reason for this is that the distance between the roughened particles is wide or grows unevenly, and therefore the adhesion with the resin is insufficient. On the other hand, if the value of Sdr is greater than 140%, a tendency to decrease the transmission characteristics can be observed. It is presumed that the reason for this is that as the Sdr becomes larger, the unevenness of the roughened particles becomes larger, and the transmission loss increases. Furthermore, the value of Sdr is preferably in the range of 20 to 120%, and more preferably in the range of 40 to 100%.

Furthermore, the reason why the transmission characteristics and reflow heat resistance are improved by controlling the surface area ratio of the roughening treatment layer is uncertain, but it can be considered that, especially when the current is concentrated due to the skin effect In the high frequency band on the surface of the conductor, there is a tendency that the current flowing through the entire surface of the roughened layer increases, so as the spread area ratio becomes higher, the transmission loss increases. In addition, if the roughened particles become fine to a certain degree of surface shape, the physical adhesion (anchor effect) between the roughened particles on the roughened surface of the surface-treated copper foil and the surface of the resin substrate tends to decrease, but By narrowing the gap between the roughened particles or making the height of the roughened particles non-uniform, the adhesion of the interface between the roughened particles and the resin substrate is improved. As a result, it is considered that blistering is less likely to occur during heating during reflow soldering, and the reflow heat resistance is improved.

Next, the influence of the spread area ratio of the surface of the roughened layer on the heat resistance of reflow will be explained. For the copper-clad laminated board formed by bonding the surface-treated copper foil and the resin substrate by hot pressing, the interface between the roughened layer of the surface-treated copper foil and the resin substrate appears due to the hot pressing There are fine voids such as defects (hereinafter, such voids are referred to as "cracks"). If the copper-clad laminate is heated during reflow soldering, the low-molecular-weight components in the resin base material volatilize in the form of gas and accumulate in the cracks to generate expansion force. At this time, when the spread area ratio is low, it can be considered that the cracks between adjacent coarse particles are easily connected and spread, and the cracks gradually propagate, so continuous peeling of the interface occurs and blistering occurs. On the other hand, if the spread area ratio is high to a certain level, the contact area between the roughened particles and the resin substrate increases, and the frictional force acting between the roughened layer and the resin substrate increases. Therefore, it can be considered that the frictional force acting between the roughening treatment layer and the resin substrate is greater than the expansion force generated by the cracks when the low molecular weight components in the resin substrate volatilize in the form of gas. , Thereby exerting the effect of restraining the propagation of cracks. As a result, it can be presumed that the propagation of cracks is not easy to proceed, the continuous peeling of the interface between the roughening treatment layer and the resin base material is suppressed, and blistering is unlikely to occur.

In addition, in the present invention, the value of the root mean square surface gradient Sdq, which is the composite parameter of the three-dimensional surface properties measured from the surface of the silane coupling layer, is preferably in the range of 25 to 70°. In addition, it was confirmed in the present invention that the value of Sdq is also the same as the value of Sdr, and the surface shape of the roughened layer constituting the surface-treated copper foil is further laminated on the roughened layer to form an antirust treatment layer and Compared with the surface shape of the silane coupling layer after the silane coupling layer, there is almost no change. Therefore, regarding Sdq, the value of Sdq measured from the surface of the silane coupling layer and the value of Sdq measured from the surface of the roughening treatment layer are also regarded as the same and specified.

再者，式中之x、y為平面坐標，Z為高度方向之坐標。Z(x，y)表示某點之坐標，藉由將其進行微分而成為在該坐標之斜率。上式係將所有點（A個）之x方向斜率與y方向斜率之平方相加並求平方根而得。The so-called Sdq refers to the surface gradient (slope) of the roughened layer. Specifically, it is the root mean square (rms) surface gradient of the surface evaluated in all directions, and is the value represented by the following formula.

Furthermore, the x and y in the formula are plane coordinates, and Z is the height coordinate. Z(x, y) represents the coordinate of a certain point, and it becomes the slope at that coordinate by differentiating it. The above formula is obtained by adding the square root of the slope in the x direction and the slope in the y direction of all points (A points).

The characteristic of Sdq is that the shape of the surface with similar arithmetic mean height Sa can be distinguished. The arithmetic average height Sa represents the average value of the absolute value of the height difference of each point relative to the average surface of the surface, so although it is suitable for judging the information of the average height of the unevenness, it cannot judge the sharpness (tilt) of the surface shape.

In contrast, the value of Sdq is affected by both the amplitude and interval of the surface shape. When the value of Sdq is small, it has a gentle surface shape. On the other hand, when Sdq becomes large, it has a sharp surface shape. The inventors tried to produce multiple surface-treated copper foils with different values of Sdq, and conducted painstaking research on the relationship with transmission characteristics and reflow heat resistance. By limiting the value of Sdq to 25-70° Range, and more appropriately control the sharpness of the roughened particles present on the surface of the roughened layer. As a result, it is possible to obtain a surface-treated copper foil with good transmission characteristics and reflow heat resistance. If the value of Sdq is less than 25°, the transmission characteristics will tend to decrease. If the value of Sdq exceeds 70°, the heat resistance of reflow will decrease. Therefore, the value of Sdq should be controlled within the range of 25~70°. The range of 30 to 65° is more preferable, and the range of 40 to 60° is further more preferable.

Furthermore, by controlling the sharpness of the roughened particles present on the surface of the roughened layer, the reason why the transmission characteristics and reflow heat resistance are improved is uncertain, but it can be considered that: The skin effect is concentrated in the high frequency band on the surface of the conductor. If the roughened particles become sharp to a certain degree of surface shape, the current cannot reach the top of the roughened particle, and it is difficult to flow in the path through the top. On the other hand, in the case of the sharp and small surface shape of the roughened particle, it can be considered that the current flowing in the high frequency band flows on the entire surface including the tip of the roughened particle, thereby increasing the transmission loss. In addition, if the sharpness of the roughened particles becomes too large, the gap between the roughened particles will be narrowed. When the surface-treated copper foil and resin are laminated, it is difficult to fill the resin to the bottom of the surface of the surface-treated copper foil (recesses). Location. As a result, it is considered that blistering is likely to occur during heating during reflow soldering, and the heat resistance of reflow soldering tends to deteriorate.

Next, the influence of the sharpness of the roughened particles constituting the surface of the roughened layer on the transmission characteristics will be explained. Figure 1 is disclosed in International Publication No. 2016/035876, in which the height of the coarsening particles is set to h, and the width of the h/2 height position of the coarsening particles is set to w, the skin depth d will be used to coarsen The height h and width w of the particles are standardized, and the calculation result of the equivalent conductivity of each roughened surface shape is shown. Specifically, the vertical axis and the horizontal axis in FIG. 1 are respectively h/d and w/d normalized by the skin depth d, and show the results of calculating the distribution of equivalent conductivity. In Figure 1, it can be seen that the equivalent conductivity is from the lower left area (equivalent conductivity: (5.5~6.0)×10 ⁷ S/m) to the upper right area (equivalent conductivity: (0~2.0)×10 ⁷ S/m) becomes lower.

The definition of equivalent conductivity is explained here. If a high-frequency current flows on the copper foil, the current distribution is concentrated in the area of the skin depth d from the surface of the copper foil, and current loss occurs at the concentrated part due to the conductor resistance. In particular, if current flows in a roughened conductor with protrusions (roughened particles) formed on the surface as a roughening treatment layer, instead of flowing in a smooth conductor without a roughening treatment layer formed on the surface, the current loss will increase. The increase in current loss due to the roughened particles present on the surface can be replaced with an equivalent increase in the loss due to the decrease in conductivity. That is, it is possible to evaluate the quality of the high-frequency characteristics of the roughened surface by the apparent conductivity. This apparent conductivity is defined as equivalent conductivity.

It is generally known that the equivalent conductivity will vary with the vertical axis of FIG. 1, that is, h/d. That is, it can be considered that the smaller the height h of the roughened particles is, the less there is a significant decrease in the equivalent electrical conductivity, which is allowable as the transmission characteristic of the copper foil. Previously, it has been known that the smaller the surface roughness, the better the transmission characteristics. Therefore, increasing the height of the roughened particles above the depth of the skin in order to ensure the adhesion will result in a decrease in the transmission characteristics, which is not ideal. In view of this previous idea, it is the same or higher than the depth of the skin. In the region where the height of the roughened particles, that is, h/d≥1, the transmission characteristics begin to deteriorate. Therefore, especially in order to obtain good transmission characteristics, it is usually difficult to adopt a surface shape with a higher roughening particle height.

In contrast, in the present invention, when w/d is 1 or less, even if h/d≥1, it is confirmed that the apparent conductivity (equivalent conductivity) does not decrease but the h/d range (area ) The tendency to expand, that is, the effect of improving the equivalent conductivity in the form of non-linear change is confirmed. By further setting w/d to 0.5 or less, the equivalent conductivity is maintained at a high state and hardly decreases , The improvement effect of equivalent conductivity can be observed. Especially when the height h of the roughened particles with h/d≥1 is higher (the surface roughness is coarser), the improvement effect of this equivalent conductivity is more significant. This finding is particularly effective when it is necessary to increase the height h of the roughened particles in order to ensure the adhesion with the resin substrate.

This phenomenon that the equivalent conductivity changes rapidly and non-linearly with the width w of the coarsened particles standardized by the skin depth d can be considered based on the principle described below.

(The width w and the current density of the roughened particles) Figure 2 (a) and (b) show the electromagnetic field analysis by applying a high-frequency electric field in the horizontal direction of the paper, and applying the high-frequency conduction current density flowing at this time on the copper foil section Shown in the conceptual diagram, the dotted line in the figure is the equal current density line. Fig. 2(a) shows a situation where the normalized width w/d value of coarse particles is relatively large, and Fig. 2(b) shows a situation where the normalized width w/d value of the coarse particles is relatively small. In addition, in Figure 2(a), point A is the point where the current density is small, and point B is the point where the current density is high. In addition, in Figure 2(b), point E is the point where the current density is relatively small, and point F is the point where the current density is relatively high.

Generally, the skin effect becomes more pronounced with the higher frequency of the conduction current. This phenomenon can be explained by the fact that the current flows more concentrated on the surface of the copper foil. This phenomenon is based on the premise that the copper foil has a smooth surface structure. Compared with the case where the surface is smooth, the current density condition when the surface has a roughened shape like the present invention becomes very special. Specifically, in both Fig. 2(a) and Fig. 2(b), it was confirmed that the current did not easily flow on the tip side of the roughened particles on the more surface side (point A, point E). At this time, what happens at the top of the roughened particle is the cancellation of the conduction current.

It is considered that this phenomenon is due to the following reasons. Most of the current is concentrated within the skin depth d on the surface of the copper foil, and when the currents flowing in the concentrated part do not interfere with each other at all, it becomes a conduction current. On the other hand, in the part below the skin depth d like the tip of the roughened particle (protrusion), when the currents in different directions interfere with each other (overlap), if the current flows in the opposite direction in the interference part, it will be cancelled. , The conduction current does not flow. For example, if the current in the direction toward the tip of the roughened particle interferes with the current flowing from the tip of the roughened particle to the base side, the current in the interfering part is canceled and the conduction current does not flow. However, this phenomenon can be considered as it is. Does not become the cause of current loss.

In more detail, the difference between the surface shapes shown in Fig. 2(a) and Fig. 2(b) will be described. In the case of Fig. 2(b), the width w of the roughened particles is narrower than that of Fig. 2(a), and the current density in the roughened particles is relatively small. For example, in the case of Figure 2(a), the surface position of the roughened particle (point D) is closer to the tip side than the position of 1/2 height of the height h of the roughened particle. The current density of the inner central point (point C) connected by the bases on both sides of the chemical particle is equivalent. That is, the current density of the surface at 1/2 height of the height h of the roughened particle is equivalent to the current density of the inner central point (point C) of the roughened particle. From this, it can be considered that Fig. 2(a) shows a state where the current easily flows to the height of the roughened particle close to the tip. Therefore, there is an increase in the current flowing on the tip side and the current flowing on the base side of the roughened particle. Less tendency.

In contrast, in the case of Figure 2(b), the surface position (point I) of the roughened particle is located at the base side compared to the 1/2 height position of the height h of the roughened particle. The current density at this position is The current density of the inner central point (point G) connected by the bases on both sides of the roughened particle is equivalent. That is, the current density of the surface at 1/2 height of the height h of the roughened particle is lower than the current density of the inner central point (point G) of the roughened particle. From this, it can be considered that, in FIG. 2(b), there is a tendency that the current flowing on the tip side of the roughened particle decreases, and the current flowing on the base side of the roughened particle tends to increase. It can be considered that the current consumption can be reduced by selecting the roughened surface structure, which is reduced on the tip side of the roughened particle (especially higher than the height of the protrusion) relative to the current flowing near the base of the roughened particle h/2 is closer to the tip side) the amount of current flowing.

In the present invention, based on this effect, by setting the value of Sdr in the range of 8 to 140%, the surface of the copper foil is roughened with an appropriate roughened shape to reduce transmission loss.

Based on the above content, in the present invention, the value of the spread area ratio Sdr of the interface, which is a composite parameter of the three-dimensional surface properties measured from the surface of the silane coupling layer, is set in the range of 8 to 140%, and it is preferable to further reduce the mean square The value of root surface gradient Sdq is set in the range of 25~70°.

In addition, the value of the aspect ratio Str, which is the spatial parameter of the three-dimensional surface properties measured from the surface of the silane coupling layer, is preferably 0.25~1, more preferably 0.30 or more, more preferably 0.50 or more Better. Str is a parameter representing the isotropy of the surface shape in the vertical and horizontal directions. The maximum value of Str is 1, and the case where the value of Str is 1 indicates complete isotropy. Generally, if the value of Str is 0.5 or more, it shows strong isotropy, on the contrary, if it is less than 0.30, it shows anisotropy. Usually, the circuit of the printed wiring board is randomly formed in the vertical, horizontal, and oblique directions. Therefore, the roughened shape exhibits isotropy in the surface of the copper foil, and the deviation of the transmission loss due to the measurement position, the measurement direction, etc., in the surface of the copper foil becomes smaller. Str is preferably close to 1. On the contrary, the smaller the value of Str, the greater the deviation of the transmission loss due to the measurement position and the measurement direction in the copper foil surface, which is not good.

Furthermore, it is preferable that the ten-point average roughness Rzjis measured from the surface of the silane coupling layer is in the range of 0.9 to 1.5 µm. The reason is that if the ten-point average roughness Rzjis is less than 0.9 µm, the adhesion, reflow heat resistance, etc. may become insufficient, and if the Rzjis exceeds 1.5 µm, the transmission loss may increase. In addition, it has been confirmed in the present invention that the values of Str and Rzjis are the same as the value of Sdr, which constitutes the surface shape of the roughened layer of the surface-treated copper foil, and the roughened layer is further laminated to form a rust preventive treatment. Compared with the surface shape of the silane coupling layer after the silane coupling layer, there is almost no change in the surface shape. Therefore, with regard to Str and Rzjis, the values of Str and Rzjis measured from the surface of the silane coupling layer and the values of Str and Rzjis measured from the surface of the roughening treatment layer are also regarded as the same and specified.

In addition, in the present invention, it is preferable that the total content of the metal other than copper and the oxide of the metal in the roughening treatment layer and the antirust treatment layer is 0.15 to 0.50 mg/dm ² in terms of metal elements. The surface shape of the roughened layer can be controlled by adding metals other than copper, such as Mo, Fe, Ni, Co, W, etc., to the roughening electroplating solution for forming the roughened layer. Well known. On the other hand, these metals have higher resistance than copper, and oxides are easily formed. Therefore, if the above-mentioned metals are excessively contained in the roughening treatment layer or the rust prevention treatment layer, it may adversely affect the transmission characteristics. Therefore, if the total content of metals other than copper and oxides of the metal in the roughening treatment layer and the antirust treatment layer is less than 0.15 mg/dm ² in terms of metal elements, it is difficult to effectively control the roughening treatment layer. Regarding the surface shape, if it exceeds 0.50 mg/dm ² , the electrical resistance will increase and the transmission characteristics will tend to deteriorate. Therefore, the total content of the metal other than copper and the oxide of the metal in the roughening treatment layer and the antirust treatment layer is preferably 0.15 to 0.50 mg/dm ² in terms of metal elements.

Furthermore, it is preferable that the contents of Ni and Zn in the roughening treatment layer and the antirust treatment layer are 0.05 to 0.30 mg/dm ^{2, respectively} . The reason is that if the contents of Ni and Zn in the roughening treatment layer and the rust prevention treatment layer are less than 0.05 mg/dm ² , respectively, the reflow heat resistance may become insufficient, and if the contents exceed 0.30, respectively mg/dm ² , the increase of Ni content will lead to the increase of transmission loss, and the increase of Zn content will lead to over-etching. As a result, the adhesion of the interface between the copper foil and the resin substrate may decrease, and the reflow heat resistance Sexual decrease.

Furthermore, the copper foil constituting the surface-treated copper foil of the present invention includes rolled copper foil or electrolytic copper foil. Generally, electrolytic copper foil deposits copper on the surface of a metal drum for foil making by electrolytic plating. The surface of the drum is called the S surface, and the opposite side is called the M surface. When the copper foil is an electrolytic copper foil, in terms of suppressing an increase in transmission loss, it is preferable to have the aforementioned roughening treatment layer only on the M surface of the electrolytic copper foil.

Furthermore, the present invention manufactures a copper-clad laminate. The copper-clad laminate has the above-mentioned surface-treated copper foil and a resin laminated on the aforementioned silane coupling layer of the surface-treated copper foil, wherein the resin has a dielectric material at a frequency of 10 GHz. With a constant of 3.5 or less and a dielectric loss tangent of 0.006 or less, a printed wiring board with low transmission loss of high-frequency electrical signals and excellent reflow heat resistance can be manufactured. Furthermore, the reason why the resin constituting the aforementioned copper clad laminate is limited to a resin with a dielectric constant of 3.5 or less and a dielectric loss tangent of 0.006 or less at a frequency of 10 GHz is that the effect of reducing transmission loss is greater.

(Production conditions of surface-treated copper foil) As the copper foil (original foil) constituting the surface-treated copper foil of the present invention, any one of a copper foil with a smooth surface and a copper foil with minute irregularities on the surface can be used. The surface shape of the M surface of the original foil A (the surface in contact with the electrolyte during the foil making) is shown in Figure 3(a). In addition, the M surface and the S surface of the original foil B (which is in contact with the electrolytic drum during the foil making) The surface properties of the contact surface are shown in Figure 3(b) and Figure 3(c), respectively.

＜Electrolysis condition of original foil A＞

＜Electrolysis condition of original foil B＞

(Formation conditions of the roughening treatment layer) The roughening treatment layer formed on the surface of the copper foil is implemented by a two-stage roughening treatment of a roughening electroplating step and a capsule electroplating step. The above-mentioned roughening electroplating step is used to form fine copper Particles, the above-mentioned capsule electroplating step is used to prevent the fine particles from falling off. In the roughening electroplating step, the copper-sulfuric acid aqueous solution added with metal ions is used as the roughening electroplating solution. As an example, preferable plating conditions are as follows.

＜Roughening plating conditions＞

In the capsule electroplating step, a copper-sulfuric acid aqueous solution is used as the capsule electroplating solution. As an example, preferable plating conditions are as follows.

＜Capsule plating conditions＞

In addition, the chloride ion concentration in the roughening plating solution and the capsule plating solution is preferably 0.3 mass ppm or less. As the raw material of electrolytic copper foil, pulverized wire scraps are usually used. This wire scrap contains oil, and if it is used directly, plating defects such as pinholes may occur. Therefore, the technology of using activated carbon to remove oil from the electroplating solution (electrolyte) is widely known. However, the activated carbon is treated with hydrochloric acid in the regeneration step, so chloride ions are adsorbed. Therefore, chloride ions are inevitably mixed in the electrolyte, and contain about several ppm.

If the chloride ion concentration is more than 0.3 mass ppm, the effects of metal ions such as Mo, Fe, Ni, Co, W, etc. cannot be fully exerted, and a uniform and fine surface shape cannot be obtained. In order to set the chloride ion concentration to 0.3 mass ppm or less, it is preferable to add a substance that can capture chloride ions and finally be removed from the electroplating solution into the electroplating solution, for example, add 0.01~0.2 mass to the electroplating solution Ag ion of about ppm. By adding Ag ions in the plating solution, Ag ions react with chloride ions to become silver chloride and precipitate. Therefore, the chloride ions can be removed from the plating solution. The precipitated silver chloride is removed from the electroplating bath with a filter, so it will not affect the roughened shape. In addition, the analysis of chloride ions uses ion chromatography.

In addition, it is preferable not to actively add organic additives to the roughening plating solution and the capsule plating solution. The reason is that if an organic additive is used, it tends to be difficult to manage the intake of the organic additive into the copper foil and the by-products produced by the oxidation reaction at the anode, and it is difficult to industrially produce it stably.

Furthermore, for the formation of the roughening treatment layer constituting the surface-treated copper foil of the present invention, it is preferable to balance the conditions to perform both roughening plating conditions and capsule plating conditions. For example, there may be mentioned: In the capsule plating conditions, the current density and processing time are mutually set appropriately. In addition, in addition to the current density and the treatment time, in order to exert the effect of making the roughened particles fine and uniform, it is preferable to appropriately select the type and amount of metal ions added to the roughening plating solution. If it is specifically exemplified, in the case of increasing the current density, it is only necessary to increase the concentration of the added metal ion. That is, the reason is that the roughened particles tend to grow unevenly by increasing the current density, but by adding a large amount of metal ions, fine and uniform roughened particles can be obtained.

Next, regarding the anti-rust treatment layer formed on the roughening treatment layer of the copper foil, the preferable range of the electroplating solution composition and electroplating conditions will be described below.

As the anti-rust treatment layer, one or more layers of various metal-containing or alloy-containing layers can be cited. As a specific example, three layers such as Ni plating layer, Zn plating layer, and chromate treatment layer can be cited. The situation is formed by layering in sequence. In addition, in addition to the Ni electroplating layer, Zn electroplating layer, and chromate treatment layer, or instead of at least one of these layers, an alloy electroplating layer of Ni-Zn, Zn-Cr, Ni-Cr, etc. can also be used. The following shows representative examples of electroplating bath compositions and electroplating conditions for forming Ni electroplated layers, Zn electroplated layers, Ni-Zn alloy electroplated layers, and chromate treated layers.

<Ni electroplating bath composition and electroplating conditions>

＜Zn electroplating bath composition and electroplating conditions＞

＜Ni-Zn alloy plating bath composition and plating conditions＞

＜Chromate treatment bath composition and treatment conditions＞

Next, on the rust-preventing treatment layer, a silane coupling layer is formed on the base layer in order to improve the adhesion with the resin. The types of silane coupling agents used include: silane coupling agents having epoxy groups, vinyl groups, amino groups, acrylic groups, methacrylic groups, and the like. These silane coupling agents have different effects due to the action of the reactive functional groups in the resin. Therefore, it is necessary to appropriately select the silane coupling agent used according to the compatibility with the resin.

Specific examples of the above-mentioned silane coupling agent include: aminoalkyltrimethoxysilane (for example, 3-aminopropyltrimethoxysilane), aminoalkyltriethoxysilane (for example, 3-amine Propyl triethoxy silane), vinyl trimethoxy silane, vinyl triethoxy silane, (3-(meth) propylene oxypropyl) trimethoxy silane, (3-(methyl) )Acrylicoxypropyl)triethoxysilane, (meth)acryloxypropyltriethoxysilane, 3-propenyloxypropyltrimethoxysilane, 3-propenyloxypropyl Triethoxysilane, styryltrimethoxysilane, styryltriethoxysilane, styrylpropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane Silane, 3-glycidoxypropyltrimethoxysilane, etc., even if they are other silane coupling agents, they can be appropriately selected and used.

Regarding the solution concentration of the silane coupling agent when the silane coupling agent is applied to the surface of the metal treatment layer, a sufficient amount of the silane coupling agent is applied to the (outermost) surface of the antirust treatment layer. And to achieve higher adhesion, it is better to set it as 0.01-15% by volume, and it is better to set it as 0.1-10% by volume. As the solvent of this solution, it is better to use water.

Furthermore, the above is only an example of the embodiment of the present invention, and various changes can be made within the scope of the patent application. [Example]

Next, try to produce the surface-treated copper foil of the present invention, and evaluate the performance, which will be described below. (Examples 1 to 42 and Comparative Examples 1 to 4) Regarding the copper foil (original foil), the original foil A and the original foil B with a thickness of 18 µm were respectively obtained under the manufacturing (electrolysis) conditions of the above two kinds of original foils. Regarding the surface roughness Rzjis of the original foil A, the S surface (the surface in contact with the electrolytic drum during foil making) is 1.5 µm, and the M surface (the surface in contact with the electrolyte during foil making) is 0.8 µm. Regarding the surface roughness Rzjis of the original foil B, the S surface is 1.5 µm and the M surface is 3.3 µm.

Next, roughening treatment I or II shown in Table 1 was performed on the original foil A or the original foil B, and roughening plating and capsule plating were performed. Table 2 shows the type of copper foil (original foil) and the surface to be treated, as well as the type of roughening treatment, roughening plating conditions, and capsule plating conditions. Furthermore, in the conditions of the roughening treatment, the limiting current density, critical current density, etc. will vary greatly depending on the composition or concentration of the plating solution (bath), and metal ion additives. Therefore, the roughening treatment shown in Table 2 The conditions are shown as an example of the composition of the electroplating bath shown above.

Then, on the roughened copper foil, use the electroplating solution shown below to form an anti-rust treatment layer composed of a nickel electroplated layer, a zinc electroplated layer and a chromate layer in sequence. Table 2 shows the adhesion amount of each layer constituting the anti-rust treatment layer. <Nickel plating bath composition and plating conditions>

＜Zn electroplating bath composition and electroplating conditions＞

＜Chromate treatment bath composition and treatment conditions＞

Then, on the anti-rust treatment layer of the copper foil, use 3-aminopropyltriethoxysilane with amino groups to form a silane coupling layer with the amount of silicon (Si) attached as shown in Table 2. Silane coupling treatment to manufacture surface-treated copper foil.

(Comparative Examples 5 and 6) Except that the roughening treatment II shown in Table 1 was used to form the roughening treatment layer, Comparative Examples 5 and 6 were treated under the same conditions as those of Examples 1 and 12 to produce surface-treated copper. Foil. Furthermore, the roughening electroplating solution and the capsule electroplating solution with higher chloride ion concentration used in the roughening treatment II shown in Table 1 only add activated carbon, and no addition is used to chlorinate the chloride ions. For the Ag ions that are precipitated and removed in the form of silver, the roughening plating solution used in the roughening treatment I shown in Table 1 and the lower chloride ion concentration in the capsule plating solution is to add activated carbon and add Ag ions to make chlorine The compound ion is precipitated and removed in the form of silver chloride.

(Comparative Example 7) In Comparative Example 7, on the M side of the original foil A, using the same method as Example 9 of Patent Document 1, Cu 20 g/L (copper sulfate pentahydrate 50 g/L), 3 -Sodium mercapto-1-propanesulfonate 0.25 g/L, cobalt ion 5.2 g/L, nickel ion 2.2 g/L, bath temperature 40℃, current density 10 A/dm ² , electrolysis time 10 seconds to form coarsening After treating the layer, use a solution of nickel (II) sulfate hexahydrate 30 g/L, molybdenum (VI) acid disodium dihydrate 60 g/L, trisodium citrate dihydrate 50 g/L, and pH 10.5. The composition is treated with a current density of 4 A/dm ² and an electrolysis time of 6 seconds, and then a chromate treatment layer is laminated by the method disclosed in Patent Document 1 to form a rust prevention treatment layer. Then, a silane coupling treatment was performed using aminopropyltriethoxysilane to produce a surface-treated copper foil.

(Production of copper clad laminate) In order to evaluate the high frequency transmission characteristics and especially the heat resistance of reflow, the surface treated copper foils obtained above were made such that the roughened surface faces the resin substrate and the thickness The 250 µm commercially available high-frequency response insulating resin substrate (Megtron 6 manufactured by Panasonic Co., Ltd.) overlaps, as an example, the pressing temperature: 200℃, pressing pressure: 3 MPa, pressing time: 120 minutes Under normal pressing conditions, lamination is performed to produce a copper-clad laminate, and circuit wiring is processed as necessary to prepare a measurement substrate.

<Characteristic evaluation of the test piece> (1) Measurement of the amount of metal adhesion For the measurement of the amount of metal adhesion in the roughening treatment layer and the anti-rust treatment layer, the surface of the sample that has not been roughened is covered with paint, and then cut In a square of 10 cm, use a mixed acid (nitric acid 1: hydrochloric acid 1 (volume ratio)) heated to 80°C to dissolve the roughened surface of the copper foil for about 3 to 5 µm, then use atomic absorption The photometer (Z-2300 manufactured by Hitachi High-Tech Co., Ltd.) quantitatively analyzes the metal mass in the obtained solution by atomic absorption analysis to obtain the metal adhesion amount.

(2) Measurement of surface roughness A contact surface roughness measuring machine (SE1700 type manufactured by Kosaka Laboratory Co., Ltd.) was used to measure the ten-point average roughness Rzjis in accordance with JIS B0601:2001. The reason for measuring the surface roughness with a contact surface roughness measuring machine is that in order to evaluate the macroscopic surface roughness of the copper foil obtained in this experiment, the three-dimensional white interference microscope for the purpose of observing the microscopic area cannot Accurately measure the difference in macroscopic surface roughness.

(3) Measurement of the parameters (S parameters) of the three-dimensional surface properties Regarding the values of Sdr, Sdq, and Str, the three-dimensional white interference microscope Wyko (Contour GT-K High Resolution CCD (Charged Coupled Device; Charge Coupled Device) manufactured by Bruker is used Element) Specifications: 1280×960 pixels), using vertical scanning white interference method (VSI) with a magnification of 10 times, from the surface of the silane coupling layer of the surface-treated copper foil to an area of 477 µm×357 µm at 3 different locations Measure and calculate the average value of these. Furthermore, no filtering is performed during the measurement.

(4) Evaluation of reflow heat resistance The evaluation of reflow heat resistance is based on IPC TM-650 2.4.24.1 "Determination of delamination time using TMA (Thermomechanical analysis)", using the above-mentioned copper clad laminate The obtained substrate for reflow heat resistance measurement was evaluated by the time until blistering occurred at 288°C (blistering time). For reflow heat resistance, the blistering time of 60 minutes or more is evaluated as "◎", the case of 45 minutes or more and less than 60 minutes is evaluated as "○", and the case of 30 minutes or more and less than 45 minutes is evaluated as "○" "Δ" is evaluated as "×" when it is less than 30 minutes. In the present invention, "◎", "○" and "Δ" are regarded as pass levels.

(5) Evaluation of transmission characteristics Regarding the transmission characteristics, a patterned film with a resist width of 300 µm was patterned on the above-mentioned copper-clad laminate by UV exposure, and then etching was performed to form a strip line with a length of 200 mm. A microstrip line is used to obtain a substrate for measuring transmission characteristics (size: length 210 mm, width 30 mm). A network analyzer (Keysight Technology N5247A) was used on the substrate for measurement of transmission characteristics, and the pass characteristic S21 was measured at a frequency of 40 GHz with a characteristic impedance of 50 Ω. For transmission characteristics, the case where the pass characteristic S21 is -28 dB or more is evaluated as "◎", the case where the pass characteristic S21 is -30 dB or more and less than -28 dB is evaluated as "○", and the case where the pass characteristic S21 is greater than and less than -33 dB The case of -30 dB is evaluated as "Δ", and the case of less than -33 dB is evaluated as "×". In the present invention, "◎", "○" and "Δ" are regarded as passing levels.

[Table 1]

[Table 2]

[table 3]

From the performance evaluation results shown in Table 3, it is known that the values of Sdr in Examples 1 to 42 are all within the appropriate range of the present invention. Therefore, both the reflow heat resistance and the transmission characteristics are at acceptable levels. In contrast, the values of Sdr in Comparative Examples 1 to 7 are all outside the appropriate range of the present invention. Therefore, at least one of the reflow heat resistance and the transmission characteristics is not at the acceptable level and is inferior. [Industrial availability]

According to the present invention, it is possible to provide a surface-treated copper foil and a copper-clad laminate, which can stably manufacture surface-treated copper foils with roughened shapes that are difficult to control by previously used indicators (parameters) such as surface area or surface roughness. The above-mentioned surface-treated copper foil is used as, for example, copper foil for high-frequency printed wiring boards used in high frequency bands exceeding several GHz. It can be used to produce high-frequency electrical signals with low transmission loss and excellent reflow heat resistance. Printed wiring board. In addition, by using a three-dimensional light interference microscope, the sharpness (surface gradient) and the development area of the surface of the surface-treated copper foil can be appropriately controlled. Furthermore, the surface-treated copper foil of the present invention can achieve high-level transmission characteristics, resin adhesion, and reflow heat resistance, and can achieve high-level multilayers for routers or servers that require high frequency bands exceeding tens of GHz. Printed wiring boards are extremely useful in industry.

none.

Fig. 1 is a graph showing the apparent conductivity measured on the surface of various surface-treated copper foils with respect to the height h and the width w of the roughened particles normalized by the skin depth d, divided into a plurality of regions. Figure 2 (a) and (b) are conceptual diagrams showing the high-frequency electric field applied in the horizontal direction of the paper in the electromagnetic field analysis, and the high-frequency conduction current density flowing at this time is shown on the cross-section of the copper foil, and Figure 2 (a) shows the case where there are roughened particles with a relatively large width w on the surface of the copper foil, and FIG. 2(b) shows the case where there are roughened particles with a relatively small width w on the surface of the copper foil. Figure 3(a)~(c) show the surface conditions of various copper foils (original foils), and Figure 3(a) is the surface SEM (Scanning Electron Microscope, Scanning Electron Microscope) photo of the M side of the original foil A (magnification) : 1000 times), Figure 3(b) is the surface SEM photo of the M side of the original foil B (magnification: 1000 times), and Figure 3(c) is the surface SEM photo of the S side of the original foil B (magnification: 1000 times) ). Figure 4(a) and Figure 4(b) are conceptual diagrams of two surface states with the same surface area but different surface roughness viewed from the geometry, and Figure 4(a) shows that the height and width of the mountain are relatively large Figure 4(b) shows the surface condition of the mountain with relatively small height and width.

Claims (7)

A surface-treated copper foil, which is on at least one side of the copper foil, and has a roughening treatment layer, an anti-rust treatment layer, and a silane coupling layer sequentially laminated on the basis of the aforementioned copper foil, and is characterized in that: The value of the spread area ratio Sdr of the interface, which is the composite parameter of the three-dimensional surface properties measured from the surface of the aforementioned silane coupling layer, is in the range of 8~140%, and the value of the root mean square surface gradient Sdq is in the range of 25~70°, and The value of the aspect ratio Str of the spatial parameters of the three-dimensional surface properties measured from the surface of the aforementioned silane coupling layer is 0.25~0.79. The surface-treated copper foil described in the first item of the scope of patent application, wherein the ten-point average roughness Rzjis measured from the surface of the aforementioned silane coupling layer is in the range of 0.9~1.5μm. The surface-treated copper foil described in item 1 or 2 of the scope of the patent application, wherein the total content of the metal other than copper and the oxide of the metal in the roughening treatment layer and the anti-corrosion treatment layer is converted into a metal element 0.15~0.50mg/dm ² . The surface-treated copper foil described in the first item of the scope of patent application, wherein the contents of Ni and Zn in the roughening treatment layer and the anti-rust treatment layer are 0.05 to 0.30 mg/dm ^{2 respectively} . In the surface-treated copper foil described in item 2 of the scope of patent application, the contents of Ni and Zn in the roughening treatment layer and the anti-rust treatment layer are respectively 0.05 to 0.30 mg/dm ² . The surface-treated copper foil described in item 3 of the scope of patent application, wherein the contents of Ni and Zn in the roughening treatment layer and the anti-rust treatment layer are respectively 0.05 to 0.30 mg/dm ² . A copper-clad laminate, characterized in that it has the surface-treated copper foil as described in any one of items 1 to 6 in the scope of the patent application, and a resin laminated on the silane coupling layer of the surface-treated copper foil, the aforementioned The resin has a dielectric constant of 3.5 or less at a frequency of 10 GHz and a dielectric loss tangent of 0.006 or less.

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