TW202302917A - Surface-treated copper foil, copper-clad laminate board, and printed wiring board - Google Patents

Abstract

This surface-treated copper foil comprises a copper foil and a surface-treatment layer formed on at least one surface of the copper foil. The amount of change in Sk given by formula (1) for the surface-treatment layer is 0.180-0.600 [mu]m. (1): Amount of change in Sk = P2 - P1 In the formula, P1 is the Sk calculated using a [lambda]s filter for which the cut off value [lambda]s is 2 [mu]m, and P2 is the Sk calculated without using this [lambda]s filter.

Description

Surface treated copper foil, copper clad laminate and printed wiring board

The invention relates to a surface-treated copper foil, a copper-clad laminate and a printed wiring board.

Copper-clad laminates are widely used in various applications such as flexible printed wiring boards. In this flexible printed wiring board, the copper foil of the copper-clad laminate is etched to form a conductive pattern (also called "wiring pattern"), and then the electronic parts are connected and assembled on the conductive pattern with solder, thereby achieving manufacture.

In recent years, in electronic devices such as personal computers and mobile terminals, with the increase in communication speed and capacity, electrical signals have become more and more high-frequency, and flexible printed wiring boards that can respond to them are required. In particular, the higher the frequency of the electrical signal, the greater the loss (attenuation) of the signal power, and the easier it is to fail to read the data, so it is necessary to reduce the loss of the signal power.

The causes of signal power loss (transmission loss) in electronic circuits can be roughly divided into two types. One is the conductor loss, that is, the loss caused by the copper foil, and the other is the dielectric loss, that is, the loss caused by the resin substrate. Conductor loss has the following characteristics, that is, there is a skin effect in the high frequency band, and the current flows on the surface of the conductor. Therefore, if the surface of the copper foil is rough, the current will flow along a complicated path. Therefore, in order to reduce the conductor loss of high-frequency signals, it is ideal to reduce the surface roughness of copper foil. Hereinafter, in this specification, when simply referred to as "transmission loss" and "conductor loss", it mainly refers to "transmission loss of high-frequency signal" and "conductor loss of high-frequency signal".

On the other hand, dielectric loss depends on the type of resin substrate, so it is ideal to use low-dielectric materials (such as liquid crystal polymers, low-dielectric polyimide) in circuit substrates where high-frequency signals flow. Formed resin substrate. In addition, the dielectric loss will also be affected by the adhesive between the copper foil and the resin substrate, so it is ideal to bond the copper foil and the resin substrate without using an adhesive. Therefore, in order to bond copper foil and a resin base material without using an adhesive, it has been proposed to form a surface treatment layer on at least one surface of the copper foil. For example, Patent Document 1 proposes a method in which a roughening treatment layer formed of roughening particles is provided on a copper foil, and a silane coupling treatment layer is formed on the outermost layer. [Prior Art Literature] [Patent Document]

[Patent Document 1] Japanese Unexamined Patent Publication No. 2012-112009

On the surface of the copper foil on which the surface treatment layer is formed, there are generally minute unevenness. For example, in the case of rolling copper foil, oil pits formed by rolling oil during rolling are formed on the surface in the form of minute unevenness. Also, in the case of the electrolytic copper foil, the grinding stripes of the rotating drum formed during the grinding will cause the precipitation of minute irregularities formed on the rotating drum side surface of the electrolytic copper foil on the rotating drum. If there are tiny concave-convex portions on the surface of the copper foil, for example, when forming a roughening treatment layer, the current concentration at the convex portion of the copper foil surface causes excessive growth of roughened particles. On the other hand, the concave and convex portions of the copper foil surface It is difficult to grow roughened particles because the current is not sufficiently supplied to the periphery. As a result, coarse roughened particles are formed on the convex portion of the surface of the copper foil. On the other hand, the roughened particles on the concave portion and the periphery of the copper foil surface are too small, especially the roughened particles near the end of the oil pit. Insufficient adhesion of the roughened particles means that the roughened particles on the surface of the copper foil are not uniformly formed. Surface-treated copper foil with many coarse roughened particles may be bonded to a resin base material, and if a force is applied to peel the surface-treated copper foil, the stress will concentrate on the coarse roughened particles and it will be easily broken. The adhesion of the resin substrate is reduced. Moreover, the surface-treated copper foil whose size of the roughened particle is insufficient may reduce the anchoring effect by the roughened particle, and may fail to obtain sufficient adhesiveness between the copper foil and the resin base material. In particular, resin substrates made of low-dielectric materials such as liquid crystal polymers and low-dielectric polyimides are more difficult to bond to copper foil than conventional resin substrates. The follow-up method. Also, although the silane coupling treatment layer has the effect of improving the adhesiveness between the copper foil and the resin base material, depending on the type, the effect of improving the adhesiveness may be insufficient.

Embodiments of the present invention are completed to solve the above-mentioned problems. In one aspect, it is intended to provide a surface-treated copper foil capable of improving adhesion to resin substrates, especially resin substrates suitable for high-frequency applications. . Moreover, the embodiment of this invention aims at providing the copper clad laminate excellent in the adhesiveness between the resin base material especially suitable for a high-frequency application, and surface-treated copper foil in another aspect. Moreover, the embodiment of this invention aims at providing the printed wiring board which is excellent in the adhesiveness between resin base material especially suitable for high frequency use, and a circuit pattern in another aspect.

In order to solve the above-mentioned problems, the inventors of the present invention obtained the following insights after intensive research on surface-treated copper foil: by adding a small amount of tungsten compound to the plating solution used to form the roughening treatment layer, the formation of tungsten on copper foil can be suppressed. Excessive growth of roughened particles on the convex part of the foil surface, and easy to form roughened particles around the concave part of the copper foil surface. Furthermore, the inventors of the present invention analyzed the surface shape of the surface-treated copper foil thus obtained, and found that the amount of change in Sk of the surface-treated layer is closely related to the surface shape, thereby completing the embodiment of the present invention.

That is, in one aspect, the embodiment of the present invention relates to a surface-treated copper foil having a copper foil and a surface-treated layer formed on at least one surface of the copper foil, The change amount of Sk represented by the following formula (1) of the said surface treatment layer is 0.180-0.600 micrometers. Change of Sk = P2 - P1 ・・・（1） In the formula, P1 is Sk calculated by applying a λs filter with a cut-off value λs of 2 μm, and P2 is Sk calculated without applying the above-mentioned λs filter.

In another aspect, an embodiment of the present invention relates to a copper-clad laminate including the above-mentioned surface-treated copper foil, and a resin-based resin substrate for the above-mentioned surface-treated layer next to the above-mentioned surface-treated copper foil. material. Moreover, embodiment of this invention relates to the printed wiring board provided with the circuit pattern formed by etching the said surface-treated copper foil of the said copper-clad laminate board in another aspect.

According to an embodiment of the present invention, in one aspect, it is possible to provide a surface-treated copper foil capable of improving the adhesiveness with a resin base material, especially a resin base material suitable for high-frequency use. Moreover, according to the embodiment of the present invention, in another aspect, a copper-clad laminate excellent in adhesion between a resin base material, especially a resin base material suitable for high-frequency applications, and a surface-treated copper foil can be provided. Furthermore, according to the embodiment of this invention, in another aspect, the printed wiring board which is excellent in the adhesiveness between resin base materials suitable for high frequency use, and a circuit pattern can be provided.

Hereinafter, preferred embodiments of the present invention will be specifically described, but the present invention should not be interpreted as being limited thereto, and various changes and improvements can be made based on the knowledge of those in the industry without departing from the gist of the present invention. wait. A plurality of constituent elements disclosed in the following embodiments can be appropriately combined to form various inventions. For example, some constituent elements may be deleted from all the constituent elements shown in the following embodiments, and constituent elements of different embodiments may be appropriately combined.

The surface-treated copper foil according to the embodiment of the present invention has a copper foil and a surface-treated layer formed on at least one surface of the copper foil. The surface treatment layer may be formed on only one side of the copper foil, or may be formed on both sides of the copper foil. When forming surface treatment layers on both surfaces of copper foil, the types of surface treatment layers may be the same or different.

The surface shape of the surface treatment layer can be specified using surface shape parameters, which can be obtained by measuring the surface shape according to ISO 25178-2:2012 and analyzing the load curve calculated from the measurement data. When explaining the load curve, first, the load area ratio will be explained. The so-called load area ratio refers to the ratio obtained by dividing the area corresponding to the cross-section of the measurement object when the three-dimensional measurement object is cut at a certain height plane by the area of the measurement field of view. In addition, in this invention, the surface treatment layer of copper foil or surface-treated copper foil, etc. are set as a measurement object. The load curve is a curve showing the load area ratio at each height. The height near 0% of the load area ratio indicates the height of the highest portion of the object to be measured, and the height near 100% of the load area ratio represents the height of the lowest portion of the object to be measured.

Next, FIG. 1 shows a typical load curve of the surface treatment layer. The load curve and the equivalent straight line derived from the load curve can be used to express the size of the protruding valleys, cores and protruding mountains of the surface treatment layer. The equivalent straight line is obtained according to item 5.2 of JIS B0681-2:2018. That is, first, move the secant line of the load curve drawn from the load area ratio of 0% along the load curve with the difference of the load area ratio being 40% from the load area ratio of 0% to 100%, and set the position where the slope of the secant line is the gentlest It is the central part of the load curve. Next, a straight line whose sum of squares of deviations in the vertical axis direction is the smallest with respect to the central portion is called an equivalent straight line. Using the equivalent straight line and load curve obtained in this way, the core portion, the protruding mountain portion, and the protruding valley portion of the object to be measured are distinguished. That is, in the measurement object, the part in the height range of the load area ratio of 0% to 100% on the equivalent straight line is the core part, the part protruding upward from the core part is the protruding mountain part, and the part concave downward from the core part To highlight the valley. In Figure 1, Sk refers to the level difference of the core part (the difference between the upper limit level and the lower limit level of the core part), Spk refers to the height of the protruding mountain part (the average height of the protruding mountain part above the core part), and Svk refers to Protruding valley depth (the average depth of the protruding valley below the core), Smr1 refers to the load area ratio separating the protruding mountain from the core, Smr2 refers to the load area ratio separating the protruding valley from the core . In addition, the protruding mountain portion refers to a particularly high region in the object to be measured. The protruding valley refers to the particularly low area of the object to be measured. The core part refers to the area other than the protruding mountains and valleys of the measurement object, that is, the area close to the average height.

The height of the protruding mountain portion Spk is the average value of the height of the protruding mountain portion, that is, the area where the height of the object to be measured is high, and refers to the average value of the height of the area with a particularly high height in the surface treatment layer. Here, regions of particularly high height in the surface treatment layer can be interpreted as regions caused by overgrown particles in particles (in particular, roughened particles). Regarding the core part, the height of the object to be measured is the average height of the region, which can be said to be the region of the average height of the surface treatment layer. Therefore, the level difference Sk of the core part can be said to be the average height of the surface treatment layer in one aspect. The difference between the largest height particle (especially coarse particle) and the smallest height particle (especially coarse particle) among the particle size (especially coarse particle). Also, if attention is paid to the fact that the core portion is the average area height of the surface treatment layer, the level difference Sk of the core portion can be interpreted as a value related to the adhesion amount of particles of average size (especially roughened particles). In short, as a result of the analysis conducted by the present inventors in the above-mentioned manner, it was found that in the surface-treated copper foil according to the embodiment of the present invention, Sk is related to the adhesion amount of particles of an average size constituting the surface-treated layer, and Spk is related to excessive The height correlation of the growing particles. In addition, in the following, the case where the coarsening particle is used as an example is demonstrated, but it should be noted that the particle is not limited to the roughening particle.

Measurement data for measuring the surface properties of the surface-treated copper foil according to the embodiment of the present invention can be acquired using, for example, laser microscopes such as a confocal laser microscope. Here, by performing Fourier transform on the measurement data, the measurement data can be separated into waveforms having various cycles and amplitudes. The inventors of the present invention think that after applying a filter that attenuates the amplitude of a waveform with a frequency in a specific range to each of the separated waveforms, and then synthesizing all the waveforms again, and analyzing the synthesized data, the measured data can be obtained. Calculate the surface properties parameters that should be paid attention to.

In the analysis of the measurement data of surface roughness, the inventors of the present invention obtained the following insights: the surface texture parameters calculated by applying the λs filter with a cut-off value λs of 2 μm and the surface texture parameters calculated without applying the λs filter By using them in combination, it is possible to obtain detailed information on the characteristic surface shape of the surface treatment layer according to the embodiment of the present invention (particularly, the adhesion state of the roughened particles constituting the surface treatment layer). Here, the λs filter is a profile filter that greatly attenuates the amplitude of a waveform of a wavelength smaller than the cutoff value λs. The λs filter is equivalent to the S filter in ISO 25178-2:2012. The magnitude of amplitude attenuation by the λs filter varies according to the wavelength of the waveform. In the wavelength of the cutoff value λs, the amplitude is attenuated to 50% of the original value, and in the waveform with a wavelength smaller than this, the amplitude can be attenuated more. The cut-off value λs of 2 μm is a size between the size of the roughened particles constituting the surface treatment layer and the size of the oil pit. The measurement data obtained by setting the cut-off value λs to 2 μm are data derived from a waveform with a shorter period than the cut-off value λs, so it can be understood as data obtained by removing the data originating from the coarsening particles. Based on this, it can be said that the difference between the surface property parameters calculated without applying the λs filter whose cut-off value λs is 2 μm, and the surface property parameters calculated by applying the λs filter is after removing the information of the oil pit The information of the surface treatment layer is the information of the roughened particles constituting the surface treatment layer.

Based on the above findings, the present inventors analyzed various surface property parameters obtained from the load curve, and found that the amount of change in Sk of the surface treatment layer represented by the following formula (1) is related to the average roughening particle constituting the surface treatment layer. Attachment is closely related. Change of Sk = P2 - P1 ・・・（1） In the formula, P1 is Sk calculated by applying a λs filter with a cut-off value λs of 2 μm, and P2 is Sk calculated without applying the above-mentioned λs filter.

Here, FIG. 2 shows a schematic schematic diagram for explaining the roughening particles and Sk constituting the surface treatment layer. As shown in FIG. 2 , the surface treatment layer includes roughened particles A with an average size and roughened particles B with excessive growth. As explained above, it can be considered that Sk is related to the adhesion amount of the average-sized roughening particles A formed on the relatively smooth portion of the surface of the copper foil. Sk is largely affected by macroscopic shapes such as oil pits. In order to read the information of the surface treatment layer more accurately, it is necessary to remove the influence of macroscopic shapes. P1 can be interpreted as the Sk value after removing the information from the coarsening particles, in other words, it is the Sk value that retains the information from the oil pits and the like. Taking the difference between P2 and P1 refers to removing the information contained in Sk derived from macroscopic shapes such as oil pits. As a result, information on roughened particles of average size can be extracted with high precision. It is considered that the average size of the roughened particles A formed on the relatively smooth portion of the copper foil surface is closely related to the adhesive force between the resin substrate and the surface treatment layer. It is considered that overgrown (coarse) coarsening particles B cause roughening and breaking, while coarsening particles B that are too small cannot be embedded into the resin substrate at all. Therefore, the adhesiveness with a resin base material can be improved by making it the surface-treated copper foil which controls the amount of change of Sk concerning the adhesion amount of the roughening particle A of an average size in an appropriate range. From the above viewpoint, the surface-treated copper foil according to the embodiment of the present invention in which the amount of change in Sk is 0.180 to 0.600 μm exhibits sufficient adhesion to the resin base material. From the viewpoint of obtaining this effect stably, the amount of change in Sk is preferably 0.180 to 0.500 μm, more preferably 0.210 to 0.410 μm.

The Sku (kurtosis) calculated without applying the above-mentioned λs filter to the surface treatment layer is preferably 2.50 to 4.50. Sku is a parameter indicating the sharpness (sharpness) of the histogram when the height histogram is created based on the average height. For example, in the case of Sku=3.00, it means that the height distribution is a normal distribution. Also, in the case of Sku>3.00, the larger the numerical value, the more concentrated the height distribution is. Conversely, in the case of Sku<3.00, the smaller the value, the more dispersed the height distribution.

The surface-treated copper foil according to the embodiment of the present invention has unevenness on the surface, and the unevenness contributes to the improvement of the adhesiveness between the copper foil and the resin base material. The Sku of the surface treatment layer becomes an index for evaluating the height distribution of the unevenness. The Sku of the surface treatment layer is 2.50 to 4.50, which means that the height distribution is a normal distribution or a distribution state close to this. On the other hand, if the Sku of the surface treatment layer is less than 2.50, it means that the height of the surface treatment layer (height from the surface of the copper foil) is intertwined with the lower part and the higher part, resulting in an unbiased distribution state of the height distribution. When the Sku of the surface treatment layer is greater than 4.50, it means that the distribution state of the height distribution is biased, that is, the surface of the surface treatment layer is a state where a certain height part protrudes and occupies many places. The height distribution of the surface treatment layer is a normal distribution or a distribution state close to it, which means that, for example, when a roughening treatment layer is formed on the surface of the copper foil, the particles that grow excessively on the convex portion of the copper foil surface, that is, coarse particles , or there are few parts where no particles are formed in the periphery of the concave part (the end of the convex part) on the surface of the copper foil. Therefore, the Sku of the surface treatment layer is 2.50 to 4.50, which means that the excessive growth of particles formed on the convex portion of the copper foil surface is suppressed, and roughened particles are also formed around the concave portion of the copper foil surface.

Surface-treated copper foil with many coarse particles and surface-treated copper foil with areas where no particles are formed are unfavorable from the viewpoint of adhesion to the resin substrate. For example, if a surface-treated copper foil with many coarse particles is bonded to a resin substrate, if a force is applied to peel the surface-treated copper foil, the stress will concentrate on the coarse particles and it will be easily broken. The sticking force is reduced instead. In addition, in surface-treated copper foil where no particles are present, the anchoring effect due to particles cannot be sufficiently ensured, and the adhesive force between the surface-treated copper foil and the resin base material may decrease. Therefore, from the viewpoint of stably obtaining adhesion to the resin substrate, the lower limit of Sku of the surface treatment layer is preferably 2.90, and the upper limit is preferably 4.10. Furthermore, the Sku of the surface treatment layer can be specified by measuring the surface roughness according to ISO 25178-2:2012, and analyzing the contour curve calculated from the measurement data.

The Sq (root mean square height) calculated without applying the above-mentioned λs filter to the surface treatment layer is preferably 0.20 to 0.60 μm. Sq is a parameter in the height direction specified by ISO 25178-2:2012, and represents the variation in the height of the convex portion on the surface of the surface treatment layer. The large Sq of the surface treatment layer means that the variation in the height of the protrusions on the surface of the surface treatment layer is large. If Sq is too large (the variation in the height of the convex portion is too large), it may become a problem from the viewpoint of quality control of industrial products. Therefore, by making Sq of the surface treatment layer into the above-mentioned range, it is possible to slightly allow variation in the height of the convex portion to secure productivity, and to perform appropriate quality control. From the viewpoint of stably obtaining this effect, the lower limit of Sq of the surface treatment layer is preferably 0.26 μm, more preferably 0.30 μm, and still more preferably 0.34 μm, and the upper limit is preferably 0.53 μm, more preferably 0.48 μm, more preferably 0.43 μm. Furthermore, the Sq of the surface treatment layer can be specified by measuring the surface roughness according to ISO 25178-2:2012, and analyzing the contour curve calculated from the measurement data.

The Sa (arithmetic mean height) calculated without applying the above-mentioned λs filter to the surface treatment layer is preferably 0.20 to 0.40 μm. Sa is a parameter in the height direction specified by ISO 25178-2:2012, which represents the average of the height difference from the mean plane. When Sa of the surface treatment layer is large, the surface of the surface treatment layer becomes rough, and therefore, when the surface treatment copper foil is adhered to the resin base material, the anchoring effect is easily exhibited. On the other hand, if the Sa of the surface-treated layer is too large, when the surface-treated copper foil is bonded to the resin base material to process a copper-clad laminate to produce a circuit board, the skin effect of the surface-treated copper foil will This results in larger transmission loss. Therefore, by making Sa of a surface treatment layer into the said range, the balance of the securing of the adhesive force of a surface-treated copper foil to a resin base material, and suppression of a transmission loss can be ensured. From the viewpoint of obtaining such an effect stably, the lower limit of Sa in the surface treatment layer is preferably 0.23 μm, more preferably 0.24 μm, and the upper limit is preferably 0.35 μm. Also, when emphasizing the suppression of transmission loss due to the skin effect and the ease of quality control as an industrial product, the surface treatment layer preferably has a Sa of 0.20 to 0.32 μm and a Sq of 0.26 to 0.40 μm. Furthermore, Sa of the surface treatment layer can be specified by measuring the surface roughness according to ISO 25178-2:2012, and analyzing the contour curve calculated from the measurement data.

The Ssk (skew) calculated without applying the above-mentioned λs filter to the surface treatment layer is preferably -1.10 to 0.60. Ssk is a parameter that expresses the degree of skewness (skew) of the histogram when the histogram of the height is created based on the average height. For example, in the case of Ssk=0.00, it means that the height distribution is symmetrical with respect to the mean line. Also, in the case of Ssk>0.00, a larger numerical value means that the height distribution is more skewed downward with respect to the average line. Conversely, in the case of Ssk<0.00, the smaller the numerical value, the more skewed the height distribution is to the upper side with respect to the average line. Therefore, Ssk of the surface treatment layer is the same as Sku, and is an index for evaluating the height distribution of unevenness of the surface treatment layer. For example, when a roughened layer is formed on the surface of copper foil, Ssk being -1.10 to 0.60 means that roughened particles that are excessively grown on the convex part of the surface of copper foil, that is, coarse roughened particles, or roughened particles on the surface of copper foil. There are few parts where roughened particles are not formed in the periphery of the concave portion (the end portion of the convex portion). On the other hand, if it is less than -1.10, it will be a state where there are many places where the roughening particle is not formed in the periphery of the recessed part on the copper foil surface. Moreover, when Ssk exceeds 0.60, it will be in the state with many roughening particles which grow excessively on the convex part of a copper foil surface. From the standpoint of obtaining stable adhesion to the resin substrate, the upper limit of Ssk of the surface treatment layer is preferably 0.40, and the lower limit is preferably -0.80. Furthermore, the Ssk of the surface treatment layer can be specified by measuring the surface roughness according to ISO 25178-2:2012, and analyzing the contour curve calculated from the measurement data.

The type of the surface treatment layer is not particularly limited, and various surface treatment layers known in the technical field can be used. Examples of the surface treatment layer include a roughening treatment layer, a heat-resistant treatment layer, an antirust treatment layer, a chromate treatment layer, a silane coupling treatment layer, and the like. These layers can be used individually or in combination of 2 or more types. Among them, the surface treatment layer preferably includes a roughening treatment layer from the viewpoint of adhesion with the resin base material. Also, when the surface treatment layer contains one or more layers selected from the group consisting of a heat-resistant treatment layer, an antirust treatment layer, a chromate treatment layer, and a silane coupling treatment layer, these layers are preferably provided on the rough surface. on the processing layer.

Here, FIG. 3 shows a schematic enlarged cross-sectional view of a surface-treated copper foil having a roughening treatment layer on one surface of the copper foil as an example. As shown in FIG. 3 , the roughening treatment layer formed on one surface of the copper foil 10 includes the roughening particles 20 and the plating layer 30 covering at least a part of the roughening particles 20 . The roughening particle 20 is formed not only in the vicinity of the center of the convex part 11 on the surface of the copper foil 10, but also in the periphery of the concave part 12 (end part of the convex part 11). In addition, the excessive growth of the roughened particles 20 formed on the protrusions 11 of the surface of the copper foil 10 is suppressed by adding a trace amount of tungsten compound to the plating solution. Therefore, the roughened particles 20 do not excessively grow into particles with a large particle size, but have a complex shape that grows in various directions. It is considered that such a structure can be obtained by controlling the change amount of Sk of the surface treatment layer within the above-mentioned range.

The roughening particles 20 are not particularly limited, and may be composed of a single element selected from the group consisting of copper, nickel, cobalt, phosphorus, tungsten, arsenic, molybdenum, chromium, and zinc, or an alloy containing two or more of these elements. form. Among them, the roughening particles 20 are preferably formed of copper or copper alloy, especially copper. The plating layer 30 is not particularly limited, and may be formed of copper, silver, gold, nickel, cobalt, zinc, or the like.

The roughening layer can be formed by electroplating. In particular, the roughened particles 20 can be formed by electroplating using a plating solution to which a trace amount of tungsten compound is added. The tungsten compound is not particularly limited, and for example, sodium tungstate (Na ₂ WO ₄ ) or the like can be used. The content of the tungsten compound in the plating solution is preferably at least 1 ppm. If it is such a content, the excessive growth of the roughening particle 20 formed in the convex part 11 will be suppressed, and the roughening particle 20 will become easy to form in the periphery of the recessed part 12. In addition, although the upper limit of content of a tungsten compound is not specifically limited, 20 ppm is preferable from a viewpoint of suppressing resistance increase.

The plating conditions for forming the roughened layer may be adjusted according to the plating apparatus to be used, and are not particularly limited, but typical conditions are as follows. In addition, each electroplating may be performed once, and may be performed plural times. (Conditions for the formation of coarse particles 20) Plating solution composition: 5-15 g/L of Cu, 40-100 g/L of sulfuric acid, 1-6 ppm of sodium tungstate Plating solution temperature: 20-50°C Electroplating Conditions: current density 30-90 A/dm ² , time 0.1-8 seconds

(Conditions for the formation of coating layer 30) Plating solution composition: 10-30 g/L Cu, 70-130 g/L sulfuric acid Plating solution temperature: 30-60°C Electroplating conditions: current density 4.8-15 A/dm ² , time 0.1 ~ 8 seconds

The heat-resistant treated layer and the rust-resistant treated layer are not particularly limited, and may be formed of materials known in the technical field. In addition, since the heat-resistant treatment layer may also function as a rust-proof treatment layer, one layer having both the functions of the heat-resistant treatment layer and the rust-proof treatment layer may be formed as the heat-resistant treatment layer and the rust-proof treatment layer. As a heat-resistant treatment layer and/or an anti-rust treatment layer, it can be formed to contain nickel, zinc, tin, cobalt, molybdenum, copper, tungsten, phosphorus, arsenic, chromium, vanadium, titanium, aluminum, gold, silver, platinum group A layer of one or more elements in the group of elements, iron, and tantalum (it can also be in any form of metal, alloy, oxide, nitride, sulfide, etc.). Among them, the heat-resistant treatment layer and/or the anti-rust treatment layer is preferably a Ni-Zn layer.

The heat-resistant treatment layer and the anti-rust treatment layer can be formed by electroplating. The conditions may be adjusted according to the plating apparatus used, and are not particularly limited. The conditions for forming the heat-resistant treatment layer (Ni—Zn layer) using a general plating apparatus are as follows. In addition, electroplating may be performed once or multiple times. Plating solution composition: 1-30 g/L Ni, 1-30 g/L Zn pH value of plating solution: 2-5 Plating solution temperature: 30-50°C Electroplating conditions: current density 0.1-10 A/ dm ² , time 0.1～5 seconds

The chromate treatment layer is not particularly limited, and can be formed of a material known in the technical field. Here, the "chromate treatment layer" in this specification refers to a layer formed from a liquid containing chromic anhydride, chromic acid, dichromic acid, chromate, or dichromate. The chromate treatment layer can contain elements such as cobalt, iron, nickel, molybdenum, zinc, tantalum, copper, aluminum, phosphorus, tungsten, tin, arsenic, titanium (also can be metal, alloy, oxide, nitride, sulfide any form of things, etc.). Examples of the chromate treatment layer include a chromate treatment layer treated with an aqueous solution of chromic anhydride or potassium dichromate, a chromate treatment layer treated with a treatment solution containing chromic anhydride or potassium dichromate, and zinc, etc. .

The chromate treatment layer can be formed by known methods such as dip chromate treatment and electrolytic chromate treatment. These conditions are not particularly limited, for example, the conditions for forming a general chromate treatment layer are as follows. In addition, chromate treatment may be performed once, and may be performed plural times. Chromate solution composition: 1-10 g/L of K ₂ Cr ₂ O ₇ , 0.01-10 g/L of Zn Chromate solution pH value: 2-5 Chromate solution temperature: 30-55°C Electrolysis conditions : Current density 0.1～10 A/dm ² , time 0.1～5 seconds (in the case of electrolytic chromate treatment)

系矽烷偶合劑等。該等中，較佳為胺基系矽烷偶合劑、環氧系矽烷偶合劑。上述矽烷偶合劑可單獨或組合2種以上使用。 作為代表性之矽烷偶合處理層之形成方法，可舉藉由塗佈上述矽烷偶合劑之1～3體積%水溶液並進行乾燥而形成矽烷偶合處理層之方法。 The silane coupling treatment layer is not particularly limited, and may be formed of materials known in the technical field. Here, the "silane coupling treatment layer" in this specification refers to a layer formed of a silane coupling agent. It does not specifically limit as a silane coupling agent, Those well-known in this technical field can be used. Examples of silane coupling agents include amino silane coupling agents, epoxy silane coupling agents, mercapto silane coupling agents, methacryloxy silane coupling agents, vinyl silane coupling agents, and imidazole silane coupling agents. mixture, three

Department of silane coupling agent, etc. Among them, amino-based silane coupling agents and epoxy-based silane coupling agents are preferred. The said silane coupling agent can be used individually or in combination of 2 or more types. A representative method for forming a silane coupling treatment layer is a method of forming a silane coupling treatment layer by applying a 1 to 3 volume % aqueous solution of the above-mentioned silane coupling agent and drying it.

It does not specifically limit as the copper foil 10, Any of electrolytic copper foil and rolled copper foil may be used. Electrodeposited copper foil is generally manufactured by electrolytically dissolving copper from a copper sulfate plating bath onto a drum of titanium or stainless steel, with a flat S-side (polished side) formed on the side of the rotating drum and the opposite side formed on the S-side The M surface (matte surface) on the side. The M surface of the electrolytic copper foil generally has a small concave-convex part. In addition, the S surface of the electrolytic copper foil has fine unevenness because the grinding stripes of the rotating drum formed during grinding are transferred. In addition, the rolled copper foil has minute irregularities on the surface because oil pits are formed by rolling oil during rolling.

The material of the copper foil 10 is not particularly limited, and when the copper foil 10 is a rolled copper foil, refined copper (JIS H3100 alloy number C1100), oxygen-free copper ( High-purity copper such as JIS H3100 alloy number C1020 or JIS H3510 alloy number C1011). Also, for example, copper alloys such as Sn-doped copper, Ag-doped copper, copper alloys added with Cr, Zr, Mg, etc., Cason-based copper alloys added with Ni, Si, etc. can also be used. In addition, in this specification, "copper foil 10" also includes the concept of copper alloy foil.

The thickness of the copper foil 10 is not particularly limited, for example, it can be set to 1-1000 μm, or 1-500 μm, or 1-300 μm, or 3-100 μm, or 5-70 μm, or 6-35 μm, or 9-18 μm.

The surface-treated copper foil having the above-mentioned structure can be manufactured according to a method well known in the technical field. Here, parameters such as the amount of change in Sk of the surface treatment layer can be controlled by adjusting the formation conditions of the surface treatment layer, especially the formation conditions of the above-mentioned roughening treatment layer.

In the surface-treated copper foil according to the embodiment of the present invention, since the variation of Sk of the surface-treated layer is controlled to 0.180-0.600 μm, the adhesion to resin substrates, especially resin substrates suitable for high-frequency applications can be improved.

A copper-clad laminate according to an embodiment of the present invention includes the above-mentioned surface-treated copper foil and a resin base material for a surface-treated layer next to the surface-treated copper foil. This copper-clad laminate can be manufactured by adhering a resin substrate to the surface-treated layer of the above-mentioned surface-treated copper foil. It does not specifically limit as a resin base material, Those well-known in this technical field can be used. Examples of resin substrates include paper-based phenolic resins, paper-based epoxy resins, synthetic fiber cloth-based epoxy resins, glass cloth-paper composite substrates, and glass cloth-glass nonwoven composite substrates. Epoxy resin, glass cloth base epoxy resin, polyester film, polyimide resin, liquid crystal polymer, fluororesin, etc. Among these, the resin substrate is preferably polyimide resin.

The bonding method between the surface-treated copper foil and the resin substrate is not particularly limited, and it can be performed according to a method known in the technical field. For example, a surface-treated copper foil and a resin base material can be laminated and bonded by thermocompression. The copper clad laminate manufactured in the above manner can be used in the manufacture of printed wiring boards.

Since the copper-clad laminate according to the embodiment of the present invention uses the above-mentioned surface-treated copper foil, the adhesion to resin substrates, especially resin substrates suitable for high-frequency applications can be improved.

A printed wiring board according to an embodiment of the present invention includes a circuit pattern formed by etching the surface-treated copper foil of the above-mentioned copper-clad laminate. This printed wiring board can be manufactured by etching the surface-treated copper foil of the said copper-clad laminate board, and forming a circuit pattern. It does not specifically limit as a formation method of a circuit pattern, Well-known methods, such as a subtractive method and a semi-additive method, can be used. Among them, the method for forming the circuit pattern is preferably a subtractive method.

When manufacturing a printed wiring board by the subtractive method, it is preferable to carry out as follows. First, a resist is coated on the surface of the surface-treated copper foil of the copper-clad laminate, and then exposed and developed to form a specific resist pattern. Next, a circuit pattern was formed by etching away the surface-treated copper foil of the part (excess part) in which the resist pattern was not formed. Finally, the resist pattern on the surface-treated copper foil is removed. In addition, various conditions in this subtraction method are not specifically limited, It can carry out according to the well-known conditions in this technical field.

Since the printed wiring board according to the embodiment of the present invention uses the above-mentioned copper-clad laminate, it is excellent in the adhesion between the resin base material, especially the resin base material suitable for high-frequency applications, and the circuit pattern. [Example]

Hereinafter, although the embodiment of this invention is demonstrated more concretely using an Example, this invention is not limited at all by these Examples.

(Example 1) A rolled copper foil (HA-V2 foil manufactured by JX Metal Co., Ltd.) with a thickness of 12 μm was prepared. After degreasing and pickling one side, a roughening treatment layer and a heat-resistant treatment layer (Ni-Zn layer ), a chromate treatment layer and a silane coupling treatment layer as the surface treatment layer, thereby obtaining a surface-treated copper foil. The formation conditions of each treatment layer are as follows. (1) Roughening treatment layer <Formation conditions of roughened particles> Plating solution composition: 11 g/L Cu, 50 g/L sulfuric acid, 5.3 ppm tungsten (derived from sodium tungstate dihydrate) Plating Liquid temperature: 27℃ Electroplating conditions: current density 46.8 A/dm ² , time 1.01 seconds Electroplating treatment times: 2 times

<Conditions for the formation of coating layer> Plating solution composition: 20 g/L Cu, 100 g/L sulfuric acid Plating solution temperature: 50°C Electroplating conditions: current density 9.6 A/dm ² , time 1.44 seconds Electroplating treatment times: 2 times

(2) Heat-resistant treatment layer <Ni-Zn layer formation conditions> Plating solution composition: 23.5 g/L Ni, 4.5 g/L Zn Plating solution pH value: 3.6 Plating solution temperature: 40°C Electroplating conditions: Current density 0.88 A/dm ² , time 0.73 seconds Electroplating treatment times: 1 time

(3) Chromate treatment layer <Formation conditions of electrolytic chromate treatment layer> Chromate solution composition: 3 g/L K ₂ Cr ₂ O ₇ , 0.33 g/L Zn Chromate solution pH value: 3.7 Chromate solution temperature: 55°C Electrolysis conditions: current density 1.42 A/dm ² , time 0.73 seconds Chromate treatment times: 2 times

(4) Silane coupling treatment layer A 1.2 volume % aqueous solution of N-2-(aminoethyl)-3-aminopropyltrimethoxysilane was applied and dried to form a silane coupling treatment layer.

(Example 2) Except having changed the following conditions, the surface-treated copper foil was obtained on the same conditions as Example 1. <Conditions for the formation of roughened particles> Plating solution composition: 11 g/L Cu, 50 g/L sulfuric acid, 5 ppm tungsten (derived from sodium tungstate dihydrate) Plating solution temperature: 27°C Electroplating conditions : current density 74.8 A/dm ² , time 0.61 seconds <formation condition of coating layer> electroplating condition: current density 8.2 A/dm ² , time 1.15 seconds <formation condition of Ni-Zn layer> electroplating condition: current density 0.63 A/ dm ² , time 0.59 seconds <Conditions for forming electrolytic chromate treatment layer> Electrolysis conditions: current density 1.81 A/dm ² , time 0.59 seconds

(Example 3) Except having changed the following conditions, the surface-treated copper foil was obtained on the same conditions as Example 1. <Conditions for the formation of roughened particles> Plating solution composition: 11 g/L Cu, 50 g/L sulfuric acid, 3 ppm tungsten (derived from sodium tungstate dihydrate) Electroplating conditions: current density 38.8 A/dm ^2. Time 1.27 seconds <Formation condition of coating layer> Electroplating condition: current density 8.2 A/dm ² , time 1.44 seconds <Ni-Zn layer formation condition> Electroplating condition: Current density 0.59 A/dm ² , time 0.73 second

(Example 4) Except having changed the following conditions, the surface-treated copper foil was obtained on the same conditions as Example 1. <Conditions for forming coarse particles> Plating solution composition: 11 g/L Cu, 50 g/L sulfuric acid, 5 ppm tungsten (derived from sodium tungstate dihydrate) Plating solution temperature: 27°C Electroplating conditions : Current density 46.8 A/dm ² , time 1.01 seconds Electroplating treatment times: 2 times

(Example 5) A rolled copper foil (HG foil manufactured by JX Metal Co., Ltd.) with a thickness of 12 μm was prepared. After degreasing and pickling one side, a roughening treatment layer, a heat-resistant treatment layer (Ni-Zn layer), and The chromate treatment layer and the silane coupling treatment layer are used as the surface treatment layer to obtain surface-treated copper foil. The formation conditions of each treatment layer are as follows. (1) Coarsening treatment layer <Formation conditions of coarsening particles> Plating solution composition: 12 g/L Cu, 50 g/L sulfuric acid, 5 ppm tungsten (derived from sodium tungstate dihydrate) Plating Liquid temperature: 27℃ Electroplating conditions: current density 48.3 A/dm ² , time 0.81 seconds Electroplating treatment times: 2 times

<Conditions for the formation of coating layer> Plating solution composition: 20 g/L Cu, 100 g/L sulfuric acid Plating solution temperature: 50°C Electroplating conditions: current density 11.9 A/dm ² , time 1.15 seconds Electroplating treatment times: 2 times

(2) Heat-resistant treatment layer <Ni-Zn layer formation conditions> Plating solution composition: 23.5 g/L Ni, 4.5 g/L Zn Plating solution pH value: 3.6 Plating solution temperature: 40°C Electroplating conditions: Current density 1.07 A/dm ² , time 0.59 seconds Electroplating treatment times: 1 time

(3) Chromate treatment layer <Formation conditions of electrolytic chromate treatment layer> Chromate solution composition: 3 g/L K ₂ Cr ₂ O ₇ , 0.33 g/L Zn Chromate solution pH value: 3.65 Chromate solution temperature: 55°C Electrolysis conditions: current density 1.91 A/dm ² , time 0.59 seconds Chromate treatment times: 2 times

(4) Silane coupling treatment layer A 1.2 volume % aqueous solution of N-2-(aminoethyl)-3-aminopropyltrimethoxysilane was applied and dried to form a silane coupling treatment layer.

(comparative example 1) The rolled copper foil (copper foil without surface treatment) used in Example 1 was used for comparison.

(Comparative example 2) Except having changed the following conditions, the surface-treated copper foil was obtained on the conditions similar to Example 1. <Conditions for the formation of coarse particles> Plating solution composition: 11 g/L Cu, 50 g/L sulfuric acid Electroplating conditions: current density 38.8 A/dm ² , time 1.27 seconds <Conditions for the formation of coating layers> Electroplating conditions: Current density 8.2 A/dm ² , time 1.44 seconds <Ni-Zn layer formation conditions> Electroplating conditions: current density 0.59 A/dm ² , time 0.73 seconds

The following characteristic evaluations were performed on the surface-treated copper foils or copper foils obtained in the above Examples and Comparative Examples. <Sk, Sku, Sq, Sa and Ssk> According to ISO 25178-2:2012, a laser microscope (LEXT OLS4000) manufactured by Olympus Co., Ltd. was used for measurement (image capture). Analysis of the captured image was performed using analysis software of a laser microscope (LEXT OLS4100) manufactured by Olympus Corporation. As a result, the average value of the values measured and analyzed at arbitrary 5 places was used. In addition, the temperature at the time of measurement was made into 23-25 degreeC. In addition, the main setting conditions of the laser microscope and analysis software are as follows. Objective lens: MPLAPON50XLEXT (magnification: 50 times, numerical aperture: 0.95, liquid immersion type: air, mechanical tube length: ∞, cover glass thickness: 0, field number: FN18) Optical zoom ratio: 1 times Scanning mode: XYZ high precision (height resolution: 60 nm, number of pixels to capture data: 1024×1024) Imported image size [number of pixels]: horizontal 257 μm x vertical 258 μm [1024 x 1024] (Evaluation length corresponds to 257 μm due to measurement in transverse direction) DIC: off Multilayer: off Laser Strength: 100 Compensation: 0 Confocal level: 0 Beam Diameter Diaphragm: Closed Take image average: 1 time Noise Reduction: On Uneven Brightness Correction: On Optical Noise Filter: On Cut-off: When measuring P1(Sk), apply λc=200 μm and λs=2 μm, and do not apply λf. When measuring P2(Sk), Sku, Sq, Sa and Ssk, apply λc=200 μm, and do not apply λs and λf. Filter: Gaussian filter Noise removal: pre-measurement processing Surface (slope) correction: implemented Brightness: adjust to the range of 30-50 Brightness is a value that should be appropriately set according to the hue of the measurement object. The above setting is a suitable value when measuring the surface of the surface-treated copper foil whose L* is -69~-10, a* is 2~32, and b* is 221. Also, regarding Sk, the amount of change in Sk is calculated according to the above formula (1). Furthermore, the λc filter is equivalent to the L filter in ISO 25178-2:2012.

<Measurement of color tone of measurement object> Using MiniScan (registered trademark) EZ Model 4000L manufactured by HunterLab as a measuring device, L*, a* and b* of the CIE L*a*b* colorimetric system were measured in accordance with JIS Z8730:2009. Specifically, the measurement target surface of the surface-treated copper foil or copper foil obtained in the above-mentioned Examples and Comparative Examples was pressed against the photosensitive part of the measuring device, and the measurement was performed without light entering from the outside. In addition, the measurement of L*, a*, and b* was performed based on the geometric condition C of JIS Z8722:2009. In addition, the main conditions of the measuring device are as follows. Optical system: d/8°, integrating sphere size: 63.5 mm, observation light source: D65 Measuring method: reflection Lighting diameter: 25.4 mm Measuring diameter: 20.0 mm Measurement wavelength, interval: 400~700 nm, 10 nm Light source: pulsed xenon lamp, 1 light emission/measurement Traceable standards: Calibration based on CIE 44 and ASTM E259 of the National Institute of Standards and Technology (NIST) Standard Observer: 10° In addition, the following object colors were used for the white tile used as a measurement standard. When measured by D65/10°, the values in the CIE XYZ color system are X: 81.90, Y: 87.02, Z: 93.76

＜Peel Strength＞ After laminating the surface-treated copper foil and the polyimide resin substrate, a circuit with a width of 3 mm was formed along the MD direction (the long side direction of the rolled copper foil). Formation of the circuit is carried out according to a usual method. Next, according to JIS C6471: 1995, when the circuit (surface-treated copper foil) is peeled off at a speed of 50 mm/minute to the 90° direction relative to the surface of the resin substrate, that is, when it is peeled vertically upward relative to the surface of the resin substrate The strength (MD90 ° peel strength). The measurement was performed 3 times, and the average value was taken as the result of the peel strength. When the peel strength is 0.50 kgf/cm or more, it can be said that the adhesion between the circuit (surface-treated copper foil) and the resin base material is good. Furthermore, since the copper foil of Comparative Example 1 could not be bonded to the polyimide resin substrate, the above-mentioned evaluation was not carried out.

Table 1 shows the results of the above characteristic evaluation.

[Table 1] Sk variation [μm] Sa [μm] Sq [μm] Ssk Sku Peel strength [kgf/cm] Example 1 0.217 0.24 0.31 0.01 3.56 0.60 Example 2 0.316 0.31 0.39 -0.40 3.11 0.85 Example 3 0.406 0.35 0.43 0.01 3.05 0.79 Example 4 0.236 0.27 0.35 0.28 4.04 0.68 Example 5 0.222 0.23 0.29 0.00 3.66 0.51 Comparative example 1 0.021 0.13 0.18 -1.30 5.65 -- Comparative example 2 0.176 0.30 0.40 0.70 4.59 0.48

As shown in Table 1, in Examples 1 to 5 in which the amount of change in Sk of the surface treatment layer was in the range of 0.180 to 0.600 μm, the peel strength of the surface treatment copper foil was high. On the other hand, the amount of change in Sk of the surface treatment layer was out of the specified range in Comparative Example 2, and the peel strength of the surface treatment copper foil was low.

With reference to the above results and the examination of the embodiments of the present invention described so far, according to the embodiments of the present invention, it is possible to provide a surface capable of improving adhesion to resin substrates, especially resin substrates suitable for high-frequency applications. Handle copper foil. Furthermore, according to the embodiment of the present invention, it is possible to provide a copper-clad laminate having excellent adhesion between a resin base material, especially a resin base material suitable for high-frequency applications, and a surface-treated copper foil. Furthermore, according to the embodiment of this invention, the printed wiring board which is excellent in the adhesiveness between the resin base material suitable for high-frequency use, and a circuit pattern especially can be provided.

10: copper foil 11: convex part 12: Concave 20: coarse particles 30: coated coating Sk: The difference between the core part (the difference between the upper limit level and the lower limit level of the core part) Spk: Protruding mountain height (the average height of the protruding mountain above the core) Svk: Protruding valley depth (average depth of protruding valleys below the core) Smr1: load area ratio separating the protruding mountain portion from the core portion Smr2: load area ratio separating the protruding valley from the core

[Fig. 1] is a typical load curve of the surface treatment layer. [ Fig. 2 ] is a schematic diagram for explaining roughening particles and Sk constituting the surface treatment layer. [ Fig. 3 ] A schematic enlarged cross-sectional view of a surface-treated copper foil having a roughened layer on one side of the copper foil.

Claims (10)

A surface-treated copper foil having a copper foil and a surface treatment layer formed on at least one side of the copper foil, The variation of Sk expressed by the following formula (1) of the surface treatment layer is 0.180-0.600 μm, Change of Sk = P2 - P1 ・・・（1） In the formula, P1 is the Sk calculated by applying the λs filter with a cut-off value λs of 2 μm, and P2 is the Sk calculated without applying the λs filter. The surface-treated copper foil according to claim 1, wherein the variation of Sk is 0.180-0.500 μm. The surface-treated copper foil according to claim 1, wherein the variation of Sk is 0.210-0.410 μm. The surface-treated copper foil according to any one of claims 1 to 3, wherein the Sku calculated without applying the λs filter to the surface treatment layer is 2.50 to 4.50. The surface-treated copper foil according to claim 4, wherein the Sku is 2.90-4.10. The surface-treated copper foil according to any one of claims 1 to 5, wherein the Sq calculated without applying the λs filter to the surface treatment layer is 0.20-0.60 μm. The surface-treated copper foil according to any one of claims 1 to 6, wherein the calculated Sa of the surface treatment layer without applying the λs filter is 0.20-0.40 μm. The surface-treated copper foil according to any one of claims 1 to 7, wherein the surface treatment layer includes a roughening treatment layer. A copper-clad laminate comprising the surface-treated copper foil according to any one of Claims 1 to 8 and a resin base material of the surface-treated layer next to the surface-treated copper foil. A printed wiring board comprising a circuit pattern formed by etching the surface-treated copper foil of the copper-clad laminate according to Claim 9.

Images