TWI802225B - Surface treated copper foil, copper clad laminate and printed wiring board - Google Patents

Abstract

The present invention is a surface-treated copper foil comprising a copper foil and a surface-treated layer formed on at least one surface of the copper foil. The amount of change in Spk represented by the following formula (1) of the surface treatment layer is 0.02 to 0.24 μm. Change in Spk = P2 - P1 ・・・（1） In the formula, P1 is the Spk calculated by applying the λs filter with a cut-off value λs of 2 μm, and P2 is the Spk calculated without applying the λs 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, the dielectric loss depends on the type of resin substrate, so in high frequency signal flow In the mobile circuit board, it is more desirable to use a resin substrate formed of low dielectric materials (such as liquid crystal polymer, low dielectric polyimide). 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. In addition, the surface-treated copper foil whose size of the roughened particles is not sufficient may reduce the anchoring effect caused by the roughened particles, and the adhesion between the copper foil and the resin base material may not be sufficiently obtained. sex.

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, after analyzing the surface shape of the surface-treated copper foil thus obtained, the present inventors found that the amount of change in Spk of the surface-treated layer is closely related to the surface shape, and thus completed 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 amount of change in Spk represented by the following formula (1) of the surface treatment layer is 0.02 to 0.24 μm.

Change of Spk=P2-P1‧‧‧(1)

In the formula, P1 is the Spk calculated by applying the λs filter whose cut-off value λs is 2 μm, and P2 is the Spk without applying the above Spk calculated by 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.

According to the embodiment of the present invention, in another aspect, there can be provided 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, 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.

10: copper foil

11: convex part

12: Concave

20: coarse particles

30: coated coating

A: Coarsening particles of average size

B: Overgrown Coarse Particles

Spk: Protruding mountain height (the average height of the protruding mountain above the core)

Sk: The difference between the core part (the difference between the upper limit level and the lower limit level of the core part)

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 Spk 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.

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 elements can be deleted from all the components shown in the following embodiments As for the constituent elements, 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 is concave downward from the core part The part is the protruding valley.

In Figure 1, Sk refers to the level difference of the core portion (the difference between the upper limit level and the lower limit level of the core portion), Spk refers to the height of the protruding mountain portion (the average height of the protruding mountain portion above the core portion), 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, the particularly high-height regions in the surface treatment layer can be interpreted as regions caused by overgrown particles among the particles (in particular, roughened particles).

The protruding valley depth Svk is the average value of the height of the protruding valley, that is, the area where the height of the measurement object is low, and refers to the average value of the height of the particularly low area in the surface treatment layer. Here, the copper foil has concave parts such as oil pits on the surface, and the surface treatment layer is formed on the surface of the copper foil, so it can be interpreted that Svk is a value related to the depth of the oil pits.

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, so the level difference Sk of the core part can be said to be the average size of particles (especially The difference between the particle with the maximum height (especially the coarse particle) and the particle with the minimum height (especially the coarse particle) among the coarse particles).

In short, as a result of the analysis conducted by the present inventors in the above-mentioned manner, the following findings were obtained: in the surface-treated copper foil according to the embodiment of the present invention, the highest value and the lowest value of Sk and the height of the particles of the average size constituting the surface-treated layer The difference is related, Spk is related to the height of the overgrown particles, and Svk is related to the depth of the oil pit. Furthermore, in the following, the case where the coarsening particles are set as particles is used as an example to explain, but it should be noted that Particles are not limited to coarse particles.

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 texture parameters that should be paid attention to.

In the analysis of the measurement data of the surface roughness, the inventors of the present invention obtained the following insight: the surface texture parameters calculated by applying the λs filter with a cutoff value λs of 2 μm and the surface texture parameters calculated without using the λs filter When used 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 is data derived from a waveform with a shorter period than the cut-off value λs, so it can be understood as the 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 obtained 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 Spk expressed by the following formula (1) of the surface treatment layer is related to the overgrowth The adhesion amount of the coarsening particles is closely related.

Change of Spk=P2-P1‧‧‧(1)

In the formula, P1 is the Spk calculated by applying the λs filter whose cutoff value λs is 2 μm, and P2 is the Spk calculated without applying the above-mentioned λS filter.

Here, FIG. 2 shows a schematic schematic diagram for explaining the roughening particles and Spk 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 Spk corresponds to the height of the portion of the roughened grains B overgrown on the convex portion of the copper foil surface that is higher than the roughened grains A of the average size. Spk is often 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 Spk value after removing the information from the coarsening particles, in other words, it is the Spk value with the information from the oil pit retained. Taking the difference between P2 and P1 refers to removing the information contained in Spk derived from macroscopic shapes such as oil pits. As a result, information on the overgrown roughening particles B can be extracted with high precision.

The surface-treated copper foil that controls the variation of Spk related to the amount of overgrown roughened particles B attached to an appropriate range can improve the adhesion between the surface-treated copper foil and the resin substrate. It can be considered that the surface-treated copper foil with many overgrown roughened particles B is easily broken due to stress concentration on the overgrown roughened particles B after being bonded to the resin base material and the surface-treated copper foil is peeled off. , and the subsequent force decreases. On the other hand, it can be considered that the surface-treated copper foil that controls the overgrown roughened particles B to an appropriate range causes the stress to be dispersed in each roughened particle centered on the average-sized roughened particle A, and as a result, the roughened particles are hard to break , The adhesive force with the resin base material is improved.

From this point of view, the surface-treated copper foil according to the embodiment of the present invention in which the amount of change in Spk is 0.02 to 0.24 μm exhibits sufficient adhesion to the resin base material. From the viewpoint of obtaining this effect stably, the amount of change in Spk is preferably 0.08-0.23 μm, more preferably 0.10-0.17 μm.

The Ssk (skew) calculated without applying the above-mentioned λs filter to the surface treatment layer is preferably -1.10~0.60.

Ssk is a parameter expressing 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 value, the more skewed the height distribution is to the upper side relative to the average line. Therefore, the Ssk of the surface treatment layer is an index for evaluating the height distribution of the unevenness of the surface treatment layer.

For example, when a roughening treatment layer is formed on the surface of copper foil, an Ssk of -1.10~0.60 means that the roughening particles that are excessively grown on the convex part of the copper foil surface are coarse roughening particles, or the Around the concave portion (the end portion of the convex portion), there were few portions where no roughened particles were formed. 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.

Both the surface-treated copper foil with many coarse particles and the 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. Power 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.

From the viewpoint of stably obtaining 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 Sa (arithmetic mean height) calculated without applying the aforementioned 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 value 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 substrate, the anchoring effect is likely to be exhibited. On the other hand, if the Sa of the surface-treated layer is too large, the skin effect of the surface-treated copper foil will cause the 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 stably obtaining the above effect, 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.

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 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 the above effects, 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 , and more preferably 0.43 μm.

Also, when emphasizing the suppression of transmission loss caused by the skin effect and the ease of quality control as an industrial product, the Sa of the surface treatment layer is preferably 0.20-0.32 μm, and the Sq is preferably 0.26-0.40 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 Sku (kurtosis) calculated without applying the above-mentioned λs filter to the surface treatment layer is preferably 2.50~4.50.

Sku is a parameter indicating the sharpness (sharpness) of the histogram when creating a height histogram 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. Therefore, the Sku of the surface treatment layer is an index for evaluating the height distribution of the unevenness.

The Sku of the surface treatment layer is 2.50~4.50, 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 a distribution state in which the height distribution is not biased. 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 2.50~4.50, 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. In this way, it is considered that the state in which the roughened particles are uniformly formed on the surface of the copper foil means that the adhesive force between the copper foil and the resin base material is good.

Therefore, the lower limit of Sku of the surface treatment layer is preferably 2.90, and the upper limit is preferably 4.10 from the viewpoint of stably obtaining adhesion to the resin substrate.

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 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 surface treatment layers include roughening treatment layers, heat-resistant treatment layers, antirust treatment layers, chromic acid Salt treatment layer, silane coupling treatment layer, etc. 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 roughened particles 20 are formed not only in the vicinity of the center of the convex portion 11 on the surface of the copper foil 10 but also in the periphery of the concave portion 12 (the end of the convex portion 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 Spk 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.

Although it does not specifically _limit as a tungsten compound, For example, sodium tungstate ( _Na2WO4 ) etc. 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. Furthermore, the upper limit of the content of the tungsten compound is not particularly limited, and from the viewpoint of suppressing the increase in resistance, it is better to Preferably it is 20ppm.

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 forming roughened particles 20)

Plating solution composition: 5~15g/L Cu, 40~100g/L sulfuric acid, 1~6ppm sodium tungstate

Plating solution temperature: 20~50℃

Electroplating conditions: current density 30~90A/dm ² , time 0.1~8 seconds

(Conditions for forming the coating layer 30)

Plating solution composition: 10~30g/L Cu, 70~130g/L sulfuric acid

Plating solution temperature: 30~60℃

Electroplating conditions: current density 4.8~15A/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: 1~30g/L Ni, 1~30g/L Zn

pH value of plating solution: 2~5

Plating solution temperature: 30~50℃

Electroplating conditions: current density 0.1~10A/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.) layer. 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: 1~10g/L K ₂ Cr ₂ O ₇ , 0.01~10g/L Zn

pH value of chromate solution: 2~5

Chromate solution temperature: 30~55℃

Electrolysis conditions: current density 0.1~10A/dm ² , time 0.1~5 seconds (in the case of electrolytic chromate treatment)

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.

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。 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 roll of titanium or stainless steel, with a flat S-side (polished side) formed on the side of the rotating roll 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. 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 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 Spk of the surface treatment layer can be controlled by adjusting the formation conditions of the surface treatment layer, especially the formation conditions of the aforementioned roughening treatment layer.

The surface-treated copper foil according to the embodiment of the present invention controls the variation of Spk of the surface treatment layer to 0.02-0.24 μm, so it can improve the compatibility with resin substrates, especially resin substrates suitable for high-frequency applications. material adhesion.

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, the surface of the part (excess part) where the resist pattern is not formed is The surface-treated copper foil is removed by etching to form a circuit pattern. 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)

Prepare a rolled copper foil (HA-V2 foil manufactured by JX Metal Co., Ltd.) with a thickness of 12 μm, degrease and pickle one side, and then form a roughening treatment layer, heat-resistant treatment layer (Ni-Zn layer), and chromate treatment in this order. layer and silane coupling treatment layer as a surface treatment layer, thereby obtaining a surface-treated copper foil. The formation conditions of each treatment layer are as follows.

(1) Coarse processing layer

<Formation Conditions of Coarsening Particles>

Plating solution composition: 11g/L Cu, 50g/L sulfuric acid, 5ppm tungsten (derived from sodium tungstate dihydrate)

Plating solution temperature: 27°C

Electroplating conditions: current density 74.8A/dm ² , time 0.56 seconds

Plating treatment times: 2 times

<Conditions for Formation of Plating Layer>

Plating solution composition: 20g/L Cu, 100g/L sulfuric acid

Plating solution temperature: 50°C

Plating conditions: current density 11.5A/dm ² , time 1.05 seconds

Plating treatment times: 2 times

(2) heat-resistant treatment layer

<Conditions for forming Ni-Zn layer>

Plating solution composition: 23.5g/L Ni, 4.5g/L Zn

pH value of plating solution: 3.6

Plating solution temperature: 40°C

Electroplating conditions: current density 0.73A/dm ² , time 0.53 seconds

Plating treatment times: 1 time

(3) Chromate treatment layer

<Formation conditions of electrolytic chromate treatment layer>

Chromate solution composition: 3g/L K ₂ Cr ₂ O ₇ , 0.33g/L Zn

pH value of chromate solution: 3.7

Chromate solution temperature: 55°C

Electrolysis conditions: current density 2.00A/dm ² , time 0.53 seconds

Number of chromate treatments: 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)

Surface-treated copper foil was obtained on the same conditions as in Example 1 except that the following conditions were changed.

<Formation Conditions of Coarsening Particles>

Plating solution composition: 11g/L Cu, 50g/L sulfuric acid, 6ppm tungsten (derived from sodium tungstate dihydrate)

Electroplating conditions: current density 38.8A/dm ² , time 1.27 seconds

<Conditions for Formation of Plating Layer>

Electroplating conditions: current density 8.2A/dm ² , time 1.44 seconds

<Conditions for forming Ni-Zn layer>

Electroplating conditions: current density 0.59A/dm ² , time 0.73 seconds

<Formation conditions of electrolytic chromate treatment layer>

Electrolysis conditions: current density 1.42A/dm ² , time 0.73 seconds

(Example 3)

Surface-treated copper foil was obtained on the same conditions as in Example 1 except that the following conditions were changed.

<Formation Conditions of Coarsening Particles>

Electroplating conditions: current density 46.8A/dm ² , time 1.01 seconds

<Conditions for Formation of Plating Layer>

Electroplating conditions: current density 9.6A/dm ² , time 1.44 seconds

<Conditions for forming Ni-Zn layer>

Electroplating conditions: current density 0.88A/dm ² , time 0.73 seconds

<Formation conditions of electrolytic chromate treatment layer>

Electrolysis conditions: current density 1.42A/dm ² , time 0.73 seconds

(Example 4)

Prepare a rolled copper foil (HG foil manufactured by JX Metal Co., Ltd.) with a thickness of 12 μm, degrease and pickle one side, and then form a roughening treatment layer, a heat-resistant treatment layer (Ni-Zn layer), a chromate treatment layer and The silane coupling treatment layer is used as a surface treatment layer, thereby obtaining a surface-treated copper foil. The formation conditions of each treatment layer are as follows.

(1) Coarse processing layer

<Formation Conditions of Coarsening Particles>

Plating solution composition: 12g/L Cu, 50g/L sulfuric acid, 5ppm tungsten (derived from sodium tungstate dihydrate)

Plating solution temperature: 27°C

Electroplating conditions: current density 48.3A/dm ² , time 0.81 seconds

Plating treatment times: 2 times

<Conditions for Formation of Plating Layer>

Plating solution composition: 20g/L Cu, 100g/L sulfuric acid

Plating solution temperature: 50°C

Electroplating conditions: current density 11.9A/dm ² , time 1.15 seconds

Plating treatment times: 2 times

(2) heat-resistant treatment layer

<Conditions for forming Ni-Zn layer>

Plating solution composition: 23.5g/L Ni, 4.5g/L Zn

pH value of plating solution: 3.6

Plating solution temperature: 40°C

Electroplating conditions: current density 1.07A/dm ² , time 0.59 seconds

Plating treatment times: 1 time

(3) Chromate treatment layer

<Formation conditions of electrolytic chromate treatment layer>

Chromate solution composition: 3g/L K ₂ Cr ₂ O ₇ , 0.33g/L Zn

pH value of chromate solution: 3.65

Chromate solution temperature: 55°C

Electrolysis conditions: current density 1.91A/dm ² , time 0.59 seconds

Number of chromate treatments: 2 times

(4) Silane coupling treatment layer

Coat N-2-(aminoethyl)-3-aminopropyltrimethoxysilane in 1.2% by volume aqueous solution and dry dry, thereby forming 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)

Surface-treated copper foil was obtained on the same conditions as in Example 1 except that the following conditions were changed.

<Formation Conditions of Coarsening Particles>

Plating solution composition: 11g/L Cu, 50g/L sulfuric acid

Electroplating conditions: current density 38.8A/dm ² , time 1.27 seconds

<Conditions for Formation of Plating Layer>

Electroplating conditions: current density 8.2A/dm ² , time 1.44 seconds

<Conditions for forming Ni-Zn layer>

Electroplating conditions: current density 0.59A/dm ² , time 0.73 seconds

<Formation conditions of electrolytic chromate treatment layer>

Electrolysis conditions: current density 1.42A/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.

<Spk, Ssk, Sa, Sq and Sku>

According to ISO 25178-2:2012, the measurement (image capture) was performed using a laser microscope (LEXT OLS4000) manufactured by Olympus Corporation. 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 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: 60nm, pixel number of imported data: 1024×1024)

Imported image size [number of pixels]: 257 μm in width x 258 μm in length [1024 x 1024]

(As measured in the transverse direction, the estimated length corresponds to 257 μm)

DIC: off

Multilayer: Off

Laser Strength: 100

Compensation: 0

Confocal level: 0

Beam Diameter Diaphragm: Closed

Image averaging: 1 time

Noise Reduction: On

Uneven Brightness Correction: On

Optical Noise Filter: On

Cut-off: When measuring P1(Spk), apply λc=200μm and λs=2μm, and do not apply λf. When measuring P2(Spk), Ssk, Sa, Sq and Sku, apply λc=200μm, 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 Spk, the amount of change in Spk 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>

The measurement of L*, a* and b* of the CIE L*a*b* colorimetric system was carried out in accordance with JIS Z8730:2009 using MiniScan (registered trademark) EZ Model 4000L manufactured by HunterLab Co., Ltd. as a measuring device. 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: 63.5mm, observation light source: D65

Measuring method: reflection

Lighting diameter: 25.4mm

Measuring diameter: 20.0mm

Measurement wavelength, interval: 400~700nm, 10nm

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 base material, a circuit with a width of 3mm was formed along the MD direction (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, the circuit (surface-treated copper foil) is measured at a speed of 50mm/min with respect to the surface of the resin substrate in a 90° direction, that is, when the surface of the resin substrate is peeled vertically upward. Strength (MD90°peel strength). The measurement was performed 3 times, and the average value thereof was taken as the result of the peel strength. If the peeling is strong If the density is 0.50kgf/cm or more, it can be said that the adhesion between the circuit (surface-treated copper foil) and the resin substrate 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 evaluation of the above characteristics.

As shown in Table 1, the surface-treated copper foils of Examples 1 to 4 in which the amount of change in Spk of the surface treatment layer was in the range of 0.02 to 0.24 μm had high peel strength.

On the other hand, the surface-treated copper foil of Comparative Example 2 in which the amount of change in Spk of the surface-treated layer was out of the specific range had low peel strength.

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. Also, 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.

Claims (9)

A surface-treated copper foil, which has a copper foil and a surface treatment layer formed on at least one side of the copper foil, the surface treatment layer is represented by the following formula (1), the amount of change in Spk is 0.02 to 0.24 μm, the amount of change in Spk =P2-P1‧‧‧(1) In the formula, P1 is the Spk calculated by applying the λs filter whose cut-off value λs is 2 μm, and P2 is the Spk calculated without applying the λs filter. The surface-treated copper foil according to claim 1, wherein the variation of Spk is 0.08-0.23 μm. The surface-treated copper foil according to claim 1, wherein the variation of Spk is 0.10-0.17 μm. The surface-treated copper foil according to any one of claims 1 to 3, wherein the Ssk of the surface treatment layer calculated without applying the λs filter is -1.10 to 0.60. The surface-treated copper foil according to claim 4, wherein the Ssk is -0.80~0.40. The surface-treated copper foil according to any one of claims 1 to 3, wherein the Sa of the surface treatment layer calculated without applying the λs filter is 0.20 to 0.40 μm. The surface-treated copper foil according to any one of claims 1 to 3, 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 7 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 8.

Images