JP2020158832A - Surface-treated copper foil, and copper-clad laminate and printed circuit board using the same - Google Patents

Abstract

To provide a surface-treated copper foil, which realizes a good transmission characteristic, adhesion property, heat resistance, and circuit-board moisture proof reliability without powder fall when used especially in a conductor circuit of a printed circuit board, and to provide a copper-clad laminate and a printed circuit board using the surface-treated copper foil.SOLUTION: A surface-treated copper foil comprises a surface-treated film including a rough-treatment layer, in which roughened particles are formed at least on the one surface of a copper-foil base material. When the cross section of the surface-treated copper foil is observed by Scanning Electron Microscope (SEM), the average particle height (h) of the roughened particles is 0.8-2.0 μm and the average ratio (h/w) of the particle height (h) to particle width (w) of the roughened particles is 1.5-4.5 in the domain of crosswise direction 75 μm of the surface-treated film. The surface-treated copper foil has 1-60 roughened particles (P) that meet the factors (I)-(IV) among the roughened particles.SELECTED DRAWING: Figure 1

Description

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

In recent years, the number of high-frequency compatible devices such as servers, routers and smartphones exceeding 1 GHz has increased, and excellent transmission characteristics are required for copper foils through which high-frequency signals actually flow. At the same time, the peel strength has been conventionally required to be at a certain level or higher as an index of reliability, and it is required to achieve both transmission characteristics and peel strength (hereinafter referred to as "adhesion") at a high level.

Generally, as a method of increasing the adhesive force between the resin base material and the surface of the copper foil, a roughening treatment layer (a layer on which roughened particles are formed) is formed on the surface by electroplating, etching, or the like, and the resin is used. A method of increasing the adhesive force by obtaining a physical adhesive effect (anchor effect) with the base material can be mentioned.
However, if the particle size of the roughened particles formed on the copper foil surface is increased in order to effectively increase the adhesive force (adhesion) between the copper foil surface and the resin base material, the transmission loss increases due to the skin effect. Resulting in.
As described above, in the copper-clad laminate, the improvement of the adhesion between the copper foil and the resin base material and the suppression of the transmission loss are in a trade-off relationship with each other.

Therefore, in the copper foil conventionally used for the copper-clad laminate, it has been studied to improve the adhesion between the copper foil and the resin base material and to suppress the transmission loss. For example, Patent Documents 1 to 4 propose a technique for improving the adhesion between a copper foil and a resin base material by appropriately controlling the shape of the roughened particles.

However, in the conventional technique as described above, since the specific surface area is increased by forming fine irregularities on the roughened surface, it is roughened depending on the type of the resin base material when it is bonded to the resin base material. Poor filling of resin on the surface may occur. In such a case, there is a problem that a gap is generated between the resin base material and the copper foil, which causes deterioration in heat resistance and moisture resistance and reliability of the substrate.

Japanese Unexamined Patent Publication No. 2017-515456 JP-A-2017-520558 Japanese Unexamined Patent Publication No. 2015-147978 Japanese Unexamined Patent Publication No. 2018-172790

Therefore, the present invention uses a surface-treated copper foil that can realize excellent transmission characteristics, adhesion, heat resistance, and substrate moisture resistance reliability, especially when used in a conductor circuit of a printed wiring board, and does not cause powder to fall off. It is an object of the present invention to provide a copper-clad laminate and a printed wiring board.

As a result of diligent studies, the present inventors have made the surface-treated copper in a surface-treated copper foil having a surface-treated film containing a roughened-treated layer in which roughened particles are formed on at least one surface of the copper foil substrate. When the cross section of the foil is observed with a scanning electron microscope (SEM), the average value of the particle heights (h) of the roughened particles is 0.8 to 0.5 in the region of 75 μm in the width direction of the surface of the surface treatment film. The average value of the ratio (h / w) of the particle height (h) to the particle width (w) of the roughened particles is 2.0 μm, and the average value of the roughened particles is 1.5 to 4.5. Of these, by configuring 1 to 60 coarse particles (P) that satisfy the following requirements (I) to (IV), it has excellent transmission characteristics and close contact, especially when used in a conductor circuit of a printed wiring board. We have found that a surface-treated copper foil capable of achieving properties, heat resistance, and substrate moisture resistance reliability can be obtained, and have completed the present invention.
-Requirement (I): The particle height (h) of the roughened particles is 1.5 to 3.5 μm.
-Requirement (II): The ratio (h / w) of the particle height (h) to the particle width (w) of the roughened particles is 2.5 to 15.
-Requirement (III): The number of nodes of the roughened particles is 10 to 25.
-Requirement (IV): The shortest root-to-root distance between the roughened particles and other roughened particles having a particle height of 1.5 μm or more closest to the roughened particles is 0.7 to 10.0 μm.

That is, the gist structure of the present invention is as follows.
[1] A surface-treated copper foil having a surface-treated film containing a roughened-treated layer in which roughened particles are formed on at least one surface of a copper foil substrate.
When observing the cross section of the surface-treated copper foil with a scanning electron microscope (SEM), in a region of 75 μm in the width direction of the surface-treated film,
The average value of the particle height (h) of the roughened particles is 0.8 to 2.0 μm.
The average value of the ratio (h / w) of the particle height (h) to the particle width (w) of the roughened particles is 1.5 to 4.5.
A surface-treated copper foil in which 1 to 60 roughened particles (P) satisfying the following requirements (I) to (IV) are present among the roughened particles.
-Requirement (I): The particle height (h) of the roughened particles is 1.5 to 3.5 μm.
-Requirement (II): The ratio (h / w) of the particle height (h) to the particle width (w) of the roughened particles is 2.5 to 15.
-Requirement (III): The number of nodes of the roughened particles is 10 to 25.
-Requirement (IV): The shortest root-to-root distance between the roughened particles and other roughened particles having a particle height of 1.5 μm or more closest to the roughened particles is 0.7 to 10.0 μm.
[2] The surface-treated copper foil according to the above [1], wherein the linear density (d) of the roughened particles is 1.0 to 1.8 particles / μm.
[3] The surface-treated copper foil according to the above [1] or [2], wherein the developed area ratio (Sdr) measured by a three-dimensional white interference type microscope is 300 to 380% on the surface of the surface-treated film.
[4] A copper-clad laminate formed by using the surface-treated copper foil according to any one of the above [1] to [3].
[5] A printed wiring board formed by using the copper-clad laminate according to the above [4].

According to the present invention, a surface-treated copper foil capable of achieving excellent transmission characteristics, adhesion, heat resistance, and substrate moisture resistance reliability, especially when used in a conductor circuit of a printed wiring board, and using a surface-treated copper foil that does not cause powder to fall off. It is possible to provide a copper-clad laminate and a printed wiring board.

FIG. 1 shows the state of the surface of the surface-treated coating film of the surface-treated copper foil of the present invention from directly above (a) as it is, (b) from the processed cross section as it is, and (c) resin filling processing. It is an example of each SEM image observed from the later processed cross section. FIG. 2 is an example of a procedure for image analysis of an SEM image of a processed cross section of a surface-treated copper foil. FIG. 3 is a diagram for explaining an example of a method for measuring coarsened particles. FIG. 4 is a diagram for explaining a method for measuring roughened particles and the like having a special shape. FIG. 5 is a diagram for explaining a method of measuring the number of coarsened particle nodes of the roughened particles. FIG. 6 is a diagram for explaining an example of a method for measuring the shortest root-to-root distance between the roughened particles and other coarsened particles having a particle height of 1.5 μm or more closest to the roughened particles. ..

An embodiment of a surface-treated copper foil according to the present invention, and a copper-clad laminate and a printed wiring board using the same will be described in detail below.

<Surface-treated copper foil>
The surface-treated copper foil according to the present invention has a surface-treated film containing a roughened-treated layer in which roughened particles are formed on at least one surface of the copper foil substrate, and scans a cross section of the surface-treated copper foil. When observed with a type electron microscope (SEM), the average value of the particle height (h) of the roughened particles is 0.8 to 2.0 μm in the region of 75 μm in the width direction of the surface of the surface treatment film. The average value of the ratio (h / w) of the particle height (h) to the particle width (w) of the roughened particles is 1.5 to 4.5, and among the roughened particles, the following requirement (I) )-(IV) are satisfied by 1 to 60 coarse particles (P).
-Requirement (I): The particle height (h) of the roughened particles is 1.5 to 3.5 μm.
-Requirement (II): The ratio (h / w) of the particle height (h) to the particle width (w) of the roughened particles is 2.5 to 15.
-Requirement (III): The number of nodes of the roughened particles is 10 to 25.
-Requirement (IV): The shortest root-to-root distance between the roughened particles and other roughened particles having a particle height of 1.5 μm or more closest to the roughened particles is 0.7 to 10.0 μm.

The surface-treated copper foil of the present invention has a copper foil substrate and a surface-treated film containing a roughening-treated layer formed by forming roughened particles on at least one surface of the copper foil substrate. The surface of such a surface-treated film is at least one surface of the outermost surface (front and back surfaces) of the surface-treated copper foil, and a state in which roughened particles formed on at least one surface of the copper foil substrate are formed. It is a roughened surface having a fine uneven surface shape that reflects the particle shape and the like. The surface of such a surface-treated film (hereinafter referred to as "roughened surface") may be, for example, the surface of a roughened-treated layer formed on a copper foil substrate, or on the roughened-treated layer. An intermediate layer such as a Ni-containing base layer, a Zn-containing heat-resistant treatment layer, and a Cr-containing rust preventive treatment layer on the surface of the silane coupling agent layer directly formed on the surface or on the roughening treatment layer. It may be the surface of the silane coupling agent layer formed through. Further, when the surface-treated copper foil of the present invention is used, for example, in a conductor circuit of a printed wiring board, the roughened surface becomes a surface (attachment surface) for adhering and laminating a resin base material. ..

Here, the state of the roughened surface of the surface-treated copper foil of the present invention is shown in FIGS. 1 (a), 1 (b) and 1 (c). FIG. 1A is an example of an SEM image obtained by observing the roughened surface of the surface-treated copper foil of the present invention as it is (without processing such as resin filling) from directly above with a scanning electron microscope (SEM). In FIG. 1B, the surface-treated copper foil is cut perpendicular to the roughened surface as it is, the cross section is precision-polished using an ion milling apparatus, and the processed cross section is scanned electron. This is an example of an SEM image observed with a microscope (SEM). Further, in FIG. 1 (c), the surface side of the surface-treated copper foil is resin-filled, then cut perpendicularly to the roughened surface, and the cross section is precision-polished using an ion milling device to obtain the processed cross section. This is an example of an SEM image observed by a scanning electron microscope (SEM).
In particular, as is clear from FIG. 1 (b), a certain number of roughened particles having a protrusion shape (hereinafter referred to as "knot") are formed on the roughened surface of the surface-treated copper foil of the present invention. ..

In the shape evaluation of roughened particles on such a special roughened surface, only the outermost node can be observed in the measurement principle when observing from the surface of the roughened surface with a contact type roughness measuring instrument or an optical microscope. It is not possible to observe the shape of each roughened particle in the entire growth direction. Therefore, in the present invention, as one method of evaluating the roughened surface, as shown in FIG. 1 (b), the formation state of the roughened particles on the roughened surface is analyzed from the cross section of the surface-treated copper foil. It was decided to define and evaluate the characteristics of the roughened surface. Specifically, it is carried out by the following method.

First, the surface-treated copper foil is cut perpendicular to the roughened surface, and the cross section is precision-polished using an ion milling device. The processed cross section is secondary with a magnification of 10,000 times at an SEM acceleration voltage of 3 kV. Observe the electron image. During SEM observation, the surface-treated copper foil is fixed horizontally on a smooth support so that the surface-treated copper foil does not warp or sag, and the surface-treated copper foil is fixed in the cross-sectional SEM photograph. The foil shall be adjusted to be horizontal.
As the observation sample for taking a cross-sectional SEM photograph, the surface-treated copper foil may be used as it is, or the observation surface may be filled with resin if necessary.

Further, the size of the roughened particles on the roughened surface is measured by image analysis of the SEM photograph obtained by the above SEM observation. FIG. 2 shows an example of the image analysis procedure. First, a cross-sectional SEM photograph having a magnification of 10,000 times as shown in FIG. 2A is obtained. Next, this cross-sectional SEM photograph is image-processed to extract a contour line having a cross-sectional shape as shown in FIG. 2 (b). Finally, as shown in FIG. 2C, only the contour line of the cross-sectional shape in the same processed cross section is extracted. It should be noted that such image processing can be performed by known processing software such as "Photoshop", "imageJ", and "Real World Paint", which are general image editing software. Specifically, it will be described in Examples described later.

The above image processing is performed to extract the roughened shape of the outermost surface from the cross-sectional SEM photograph of the surface-treated copper foil. Therefore, the above processing is not required when observing the cross section of the test piece in which the surface side of the copper foil is resin-filled or the cross section of the circuit board bonded to the resin base material.

Next, the roughened particles are specified based on the extracted outline of the cross-sectional shape and FIG. 2C, and various dimensions are measured. It should be noted that such measurement can be performed by known processing software such as "WinROOF" and "Photo Ruler", which are general image measurement software. Specifically, it will be described in Examples described later. Hereinafter, an example of the simplest method for measuring coarsened particles is shown in FIG.

First, as shown in FIG. 3A, for the convex portion (roughened particles) to be measured on the contour line, a line L passing through the apex V of the convex portion is drawn in the growth direction of the particles. Next, as shown in FIG. 3B, a rectangle (including a square) Sq having two upper and lower sides perpendicularly intersecting the line L is drawn. In this rectangle Sq, the upper side intersects the apex V, and one of the corners of the lower side intersects the root of the convex portion far from the apex (this angle is referred to as "R1"). Further, the other corner of the lower side of the rectangle Sq (this corner is referred to as "R2") is an orthogonal point between one side extending parallel to the line L from the upper side direction and the lower side. However, the one side is drawn so as to pass through the other side of the base of the convex portion (this point is referred to as "R2'"). Then, as shown in FIG. 3C, of the sides of such a rectangle Sq, the dimension of one side parallel to the line L is defined as the particle height (h) of the coarsened particles, and the side perpendicular to the line L. Let the dimension be the particle width (w) of the roughened particles. In addition, except for the following special example, all the convex portions measured by drawing the rectangle Sq are regarded as one roughened particles.

When observing the cross section of the test piece in which the surface side of the copper foil is resin-filled or the cross section of the circuit board bonded to the resin base material, the cross section can be observed as it is without extracting the contour line. , The roughened particles existing diagonally behind the cut surface may be partially cut and reflected in the observation cross section. Such roughened particles appear to float from the surface-treated copper foil in the observed cross section, but such roughened particles are not measured.

Further, an example of not measuring as roughened particles and a method of measuring roughened particles having a special shape will be described with reference to FIG. 4 as necessary.
First, although not particularly shown, among the convex portions measured by the above criteria, those having a particle height (h) of less than 0.2 μm do not affect the transmission characteristics and adhesions of interest in the present invention. In addition, since accurate measurement is difficult, it is not included in the measurement target, and in this case, it is not included in the "roughened particles" of the present invention.

Further, as shown in FIG. 4A, the ratio (h / w) of the particle height (h) to the particle width (w) is less than 0.40 among the convex portions measured by the above criteria. Since the particles do not affect the transmission characteristics and adhesions of interest in the present invention, they are not included in the observation target and are not included in the "roughened particles" of the present invention.

Further, FIG. 4B is a measurement example of a convex portion having two or more vertices. In this case, as shown in FIG. 4B, each vertex may be regarded as one particle and measured based on the above definition.

Further, FIG. 4C is a measurement example of a convex portion having two or more steps near the root. In this case, the root is determined from the viewpoint of to what part of the convex portion the transmission characteristics and adhesions of interest in the present invention affect. That is, the angle R1 that intersects the root of the convex portion that intersects with the one farther from the apex is set to the position of the lowest step of the root. In this case, the growth direction of the particles is determined as the whole particles.

Further, in FIG. 4 (d), there is yet another convex portion on the convex portion having a relatively ambiguous root with a dimensional ratio (h / w) of less than 0.40 as shown in FIG. 4 (a). This is a measurement example when there is. In this case, the ambiguous root is not a measurement target, and the convex portion having a distinguishable root may be focused on and measured based on the above definition. This is because the gentle convex portion having an ambiguous root does not affect the transmission characteristics and adhesions of interest in the present invention.

Further, for the roughened particles having a shape other than the above, the particle height (h) and the particle width (h) and the particle width ( w) is measured.

Then, based on the particle height (h) and particle width (w) of the roughened particles measured as described above, and the number of the roughened particles, the particle height in the region of 75 μm in the width direction of the observation field ( h), the average value of the ratio (h / w) of the particle height (h) to the particle width (w) and the particle width (w), and the linear density (d) of the roughened particles are calculated.

Further, among the roughened particles observed in the region of 75 μm in the width direction of the observation field of view, the roughened particles satisfying the following requirements (I) to (IV) are certified as specific roughened particles (P), and the number thereof. To measure.
-Requirement (I): The particle height (h) of the roughened particles is 1.5 to 3.5 μm.
-Requirement (II): The ratio (h / w) of the particle height (h) to the particle width (w) of the roughened particles is 2.5 to 15.
-Requirement (III): The number of nodes of the roughened particles is 10 to 25.
-Requirement (IV): The shortest root-to-root distance between the roughened particles and other roughened particles having a particle height of 1.5 μm or more closest to the roughened particles is 0.7 to 10.0 μm.

Hereinafter, the method for certifying the specified roughened particles (P) will be described in detail.
First, among the roughened particles observed in the region of 75 μm in the width direction of the observation field of view, the roughened particles satisfying the above requirements (I) and (II) are extracted as the roughened particles (p). Such roughened particles (p) do not fall off and contribute to the improvement of adhesion.

Next, among the roughened particles (p), the roughened particles satisfying the above requirement (III) are extracted as the roughened particles (p'). Since the anchor effect of such roughened particles (p') works more effectively, the peel strength cannot be expressed only by the effect of the particle height (h) and the ratio of the particle height to the particle width (w). Bring improvement.
Hereinafter, a method for measuring the number of nodes (hereinafter, may be simply referred to as “roughened particle nodes”) of the roughened particles specified in the requirement (III) will be described with reference to FIG.
First, as shown in FIG. 5A, the apex V, the line L, the point R1, the point R2, and the point R2'are identified for the coarsened particles (p) to be measured according to the above method. Next, as shown in FIG. 5 (b), straight lines k ₁ , k ₂ , ..., K _n perpendicular to the line L of the roughened particle (p) to be measured are straight lines passing through the root R2'. Pull in the direction of the apex V at intervals of 0.05 μm from k ₁ . Next, as shown in FIG. 5 (c), each of the straight lines k ₁ , k ₂ , ..., K _n has an intersection with the region surrounded by the contour line of the roughened particles (p). Is specified, and the dimensions t ₁ , t ₂ , ..., T _n of the common portion are measured. The dimensions t ₁ , t ₂ , ..., T _n need not be the dimensions of one continuous line segment, and there are two intersections with the straight line k ₂₉ , for example, k _29. If there is more than that, the sum of these two or more line segments is measured as the dimension t ₂₉ . Then, based on each measured dimension t _n , m satisfying the following formula (i) is obtained, and the number of m is obtained as the number of roughened particle nodes of the roughened particles (p).
( _Tm −t _m-1 ) × (t _{m + 1} −t _m ) <0 (m = 2, 3, ..., n-1) ... (i)
Among the roughened particles (p), the roughened particles having 10 to 25 roughened particle nodes are extracted as the roughened particles (p').

Further, among the roughened particles (p'), the roughened particles satisfying the above requirement (IV) are certified as specific roughened particles (P).
Hereinafter, with reference to FIG. 6, a method for measuring the shortest root-to-root distance with the closest coarsened particles having a particle height of 1.5 μm or more, which is defined in the requirement (IV), will be described.
First, as shown in FIG. 6, among the coarse particles having a particle height of 1.5 μm or more existing on the left side of the coarse particles (p') to be measured, the closest other roughened particles are coarsened. Among the roughened particles having a particle height of 1.5 μm or more existing on the right side of the chemicalized particles (q1) and the roughened particles (p'), the other roughened particles closest to each other are specified as the roughened particles (q2). .. Next, roughening particles (p ') roots 2 points R1 _p', R2 and one of _'p', by connecting one of the root 2 points _R1 q1, R2 _'q1 of roughening particles (q1) 4 among types of line segments (in the case of FIG. 6, the dimensions of R1p'-R2 _'q1) combination of line segments of dimensions dimensions is minimized and, measured as left shortest root distance (x1). Similarly, four types of line segments formed by connecting one of the two root points R1p'and R2p' of the roughened particle (p') and one of the two root points R1 _q2 and R2' _q2 of the roughened particle (q2). among min (in the case of FIG. 6, R2 _'p' dimensions -R1 _q2) a combination of line segments dimension size is minimized to be measured as the right shortest base distance (x2). Then, the shorter dimension of x1 and x2 is recognized as the shortest root-to-root distance (x) with other roughened particles having a particle height of 1.5 μm or more closest to the roughened particles (p'). .. However, when the coarsened particles (q1) or the roughened particles (q2) are not present in the observation field of view, the measurement dimension of x1 and x2 is defined as the shortest root-to-root distance (x).
As shown in FIG. 6, there are particles between the roughened particles (p') and the roughened particles (q1), or between the roughened particles (p') and the roughened particles (q2). Other coarse particles with a height of less than 1.5 μm may be present.

In the present invention, among the roughened particles (p'), the roughened particles having the shortest root-to-root distance (x) of 0.7 to 10.0 μm are recognized as specific roughened particles (P).
The roughened particles (p') themselves can contribute to the improvement of adhesion, but other coarsening particles having a particle height of 1.5 μm or more at a close distance (within 10.0 μm in the distance between roots). The presence of particles can further improve adhesion. However, if other roughened particles having a particle height of 1.5 μm or more are too close to the roughened particles (p'), the roughened particles (p') are produced when the copper-clad laminate is produced. ) Is not sufficiently filled with the resin of the resin base material, so that a gap tends to be formed between the resin base material and the copper foil.
Therefore, among the roughened particles (p') that satisfy the above requirements (I) to (III), the anchor effect is particularly excellent, and a gap is unlikely to occur between the resin base material and the copper foil, and the above requirement (IV). ) Satisfying the specified roughened particles (P) in the present invention.

Since the identification and measurement of the various roughened particles are for determining the contour line, some errors may occur depending on different measurers. However, such an error can be sufficiently minimized by observing a region of 75 μm in the width direction and averaging the measurement results of a large number of coarsened particles.

Specifically, the particle height (h) and particle width (w) of the roughened particles are measured for each cross-sectional photograph based on the above criteria, and the roughened particles existing around 75 μm in the width direction of the observation field. The number of (observation target particles) and the number of specific roughened particles (P) are measured.
Although it depends on the size of the cross-sectional photograph, for example, when the observation field of view per cross-sectional photograph is 12.5 μm in the width direction, the total of 6 arbitrary points (6 cross-sectional photographs) is an area of 75 μm in the width direction. It is the observation result of. Further, although it depends on the size and number of cross-sectional photographs, when the total observation field of view is 75 μm or more in the width direction, the value obtained by converting the measured value into about 75 μm in the width direction is used as the observation result.
A more specific measurement method and calculation method will be described in Examples described later.

Hereinafter, the characteristics of the roughened particles on the roughened surface of the surface-treated copper foil of the present invention will be individually described.

On the roughened surface, the average value of the particle height (h) of the roughened particles is 0.8 to 2.0 μm, preferably 0.8 to 1.4 μm, and more preferably 1.0 to 1. It is .4 μm. Within the above range, excellent transmission characteristics, adhesion, heat resistance, and substrate moisture resistance reliability can be realized. If the average value of the particle height (h) of the roughened particles is less than 0.8 μm, the adhesion, heat resistance and substrate moisture resistance reliability tend to decrease, and if it exceeds 2.0 μm, the transmission characteristics deteriorate. Tend to do.

The average value of the width (w) of the roughened particles is preferably 0.2 to 1.0 μm, more preferably 0.2 to 0.6 μm, and further preferably 0.3 to 0.5 μm. Is. In particular, when the average value of the width (w) of the roughened particles is 0.5 μm or less, the heat resistance can be further improved.

The average value of the ratio (h / w) of the particle height (h) to the particle width (w) of the roughened particles is 1.5 to 4.5, preferably 1.6 to 4.0. Yes, more preferably 2.0 to 4.0, still more preferably 2.4 to 4.0. Within the above range, excellent adhesion, heat resistance, and substrate moisture resistance reliability can be realized without powder falling. In particular, the adhesion can be further improved by setting the average value of the ratio (h / w) to 2.0 or more. Even if the average value of the ratio (h / w) exceeds 4.5, it is meaningless, and rather tends to cause poor powder removal.

The linear density (d) of the roughened particles on the roughened surface is preferably 0.5 to 2.5 particles / μm, more preferably 0.8 to 2.1 particles / μm, and further. It is preferably 1.0 to 1.8 pieces / μm. In particular, when the linear density (d) of the roughened particles is 0.8 particles / μm or more, better adhesion and heat resistance can be realized. Further, when the linear density (d) of the roughened particles is 2.1 particles / μm or less, more excellent transmission characteristics can be realized. The linear density (d) of the roughened particles is a value calculated from the number of roughened particles (observation target particles) existing around 75 μm in the width direction of the observation field, and is per unit line region (width region). Means the particle number density of.

The number of specific roughened particles (P) on the roughened surface is 1 to 60, preferably 3 to 60, more preferably 3 to 48, and even more preferably 3 to 36. It is an individual. Within the above range, excellent transmission characteristics, heat resistance, and substrate moisture resistance reliability can be realized. When the number of the specified roughened particles (P) is 0, the heat resistance and the moisture resistance reliability of the substrate tend to decrease, and when the number exceeds 60, the transmission characteristics tend to decrease.

By the way, conventionally, as a parameter representing the surface shape of a copper foil, ten-point average roughness Rzjis has been generally used, but in ten-point average roughness Rzjis, the height direction with respect to the two-dimensional cross-sectional shape of the surface. Only the information of was included, and sufficient evaluation could not be performed. On the other hand, since the developed area ratio (Sdr) includes three-dimensional information on the surface, more appropriate characteristic evaluation becomes possible.

The developed area ratio (Sdr) means the ratio of the area added according to the surface texture with reference to the ideal surface having the size of the measurement area, and is defined by the following formula (iii).

In the above equation (iii), x and y are plane coordinates, and z is the height direction coordinates. z (x, y) indicates the coordinates of a certain point, and by differentiating this, the slope at that coordinate point is obtained. Further, A is a flat area of the measurement area.

Further, the developed area ratio (Sdr) is measured and evaluated by measuring and evaluating the unevenness difference on the copper foil surface by, for example, a three-dimensional white interference type microscope, a scanning electron microscope (SEM), an electron beam three-dimensional roughness analyzer, or the like. Can be sought. In general, the developed area ratio (Sdr) tends to increase as the spatial complexity of the surface texture increases, regardless of the change in surface roughness (Sa).
In the present invention, by measuring the developed area ratio (Sdr) as the average information of many roughened particles on the roughened surface, more appropriate characteristic evaluation becomes possible.

In the surface-treated copper foil of the present invention, the developed area ratio (Sdr) measured by a three-dimensional white interference type microscope is preferably 250 to 400%, more preferably 290 to 390% on the roughened surface. More preferably, it is 300 to 380%. In particular, when the developed area ratio (Sdr) is 290% or more, more excellent adhesion and heat resistance can be realized. Further, when the developed area ratio (Sdr) of the roughened particles is 390% or less, more excellent transmission characteristics can be realized.

Further, according to the surface-treated copper foil of the present invention, by using this in the conductor circuit of the printed wiring board, it is possible to highly suppress the transmission loss when transmitting a high frequency signal having a frequency of, for example, 1 GHz or more, and the temperature is high. It is possible to obtain a printed wiring board which can maintain good adhesion between the surface-treated copper foil and the resin base material even under high humidity and has excellent durability under harsh conditions.

<Manufacturing method of surface-treated copper foil>
Next, an example of a preferred method for producing the surface-treated copper foil of the present invention will be described. In the present invention, it is preferable to perform a roughening treatment for forming roughened particles on the surface of the copper foil substrate.

(Copper foil substrate)
As the copper foil substrate, it is preferable to use an electrolytic copper foil or a rolled copper foil having a smooth and glossy surface without coarse irregularities. Above all, it is preferable to use an electrolytic copper foil from the viewpoint of productivity and cost, and in particular, it is more preferable to use an electrolytic copper foil having smooth both sides, which is generally called "double-sided glossy foil".

In the electrolytic copper foil, the smooth and glossy surface is, for example, the S (shiny) surface in the ordinary electrolytic copper foil, and both the S surface and the M (matte) surface in the double-sided glossy foil. The smooth and glossy surface is the M surface. In the present invention, when any electrolytic copper foil is used, it is preferable to perform a roughening treatment described later on a smoother and glossy surface.

By the way, in the electrolytic copper foil, there are slight irregularities even on the smooth surface as described above. Such unevenness is derived from the surface shape of the cathode surface when the electrolytic copper foil is produced. Normally, the cathode surface of titanium or the like is kept smooth by buffing, but a slight polishing mark remains. Therefore, the S surface formed with the cathode surface as the precipitation surface has a replica shape to which the polishing marks on the cathode surface are transferred, and the M surface is a surface that follows or is affected by the polishing marks on the cathode surface. It becomes a shape. On the S and M surfaces of such an electrolytic copper foil, streak-shaped protrusions or recesses derived from polishing marks on the cathode surface are formed. However, the streaky protrusions or recesses on the S-plane and the M-plane are very macroscopic and have different scales when compared with the particle size of the roughened particles to be formed by the present invention. Therefore, such streaky protrusions or recesses give undulations to the baseline of the roughened surface, but do not affect the shape of the roughened particles formed on it. Therefore, although it is not intentionally explained in the above definition, it goes without saying that macro unevenness such as waviness of the roughened surface is not a measurement target as roughened particles in the present invention.

(Roughening process)
As the roughening treatment, for example, it is preferable to perform the roughening plating treatment (1) as shown below. Further, the fixed plating treatment (2) may be combined as needed, and it is more preferable to perform the fixed plating treatment (2) as shown below after the roughening plating treatment (1).

・ Rough plating treatment (1)
The roughening plating treatment (1) is a treatment for forming roughened particles on at least one surface of the copper foil substrate. Specifically, the plating treatment is performed in a copper sulfate bath. In such a copper sulfate bath (basic bath for roughened plating solution), molybdenum (Mo), arsenic (As), antimony (Sb), and bismuth are used for the purpose of preventing roughened particles from falling off, that is, "powder falling off". Conventionally known additives such as (Bi), selenium (Se), tellurium (Te), and tungsten (W) can be added. As a result of diligent research, the present inventor has found that the following factors affect the surface properties of surface-treated copper foil, and by setting these conditions precisely, it is possible to suppress powder falling and transmission characteristics. It was found that the adhesion, heat resistance and moisture resistance and reliability of the substrate can be satisfied at a high level.

First, if the copper concentration of the copper sulfate bath in the rough plating treatment (1) is less than 10 g / L, the shape of the roughened particles becomes excessively thin, that is, the ratio (h / w) value becomes excessively large. Therefore, there is a tendency for powder to fall off easily. Further, when the copper concentration in the plating bath exceeds 30 g / L, copper ions are efficiently supplied in the vicinity of the roughened particles in which the crystals are growing, so that the growing roughened particles generate more copper ions. The force that seeks to extend far, that is, the force that tries to grow in the height direction, is removed, and the particle height relative to the height (h) of the roughened particles and the particle width (w) of the roughened particles. Each of the ratios (h / w) of (h) becomes smaller. Further, when the copper concentration in the plating bath is high, the diffusion of copper ions is promoted, so that the roughened particles are densely formed, and the linear density (d) of the roughened particles tends to be excessively high. .. As a result, heat resistance tends to deteriorate. Therefore, the copper concentration is preferably 10 to 30 g / L.

In particular, in the present invention, as the anode electrode, a structure in which a plurality of (for example, three or more) anodes connected to one rectifier and whose dimensions in the copper foil transport direction are gradually lengthened are arranged in the copper foil transport direction (for example, three or more). Hereinafter, it is desirable to adopt "lattice-shaped anode").
By using such a grid-shaped anode, in the roughening treatment process of the roughening treatment plating (1), the area of the anode gradually increases, and the current density gradually decreases, and the plating is performed periodically. You will be able to process it. As a result, the starting point of nucleation of roughened plating is likely to occur not only on the surface of the copper foil substrate but also on the side surfaces of the roughened particles that have already been generated, so that a plurality of protrusions are formed on the side surfaces and a predetermined number of protrusions are formed. It is possible to form roughened particles having the roughened particle nodes of.
For example, anode 1 (width d ₀ , length d ₁ in the copper foil transport direction, current density J ₁ ), anode 2 (width d ₀ , length d ₂ in the copper foil transport direction, current) in the order in which the copper foil passes. It is assumed that the density J ₂ ) and the anode 3 (width d ₀ , length d ₃ in the copper foil transport direction, current density J _3, ) are installed. At this time, assuming that the ratio of the lengths d ₁ , d ₂ and d ₃ of each anode in the copper foil transport direction is d ₁ : d ₂ : d ₃ = 1: 2: 3, the current density J of each anode The ratio of ₁ , J ₂ and J ₃ is J ₁ : J ₂ : J ₃ = 3: 2: 1. The specific dimensions of each anode may be appropriately adjusted so as to have a large average current density as in the embodiment.
The average current density is obtained by averaging the current density values of a plurality of anodes having different dimensions in the copper foil transport direction by the number of anodes. That is, in the case of the device configuration of the above example, the average current density is [(J ₁ + J ₂ + J ₃ ) / 3].

Next, the electrolytic conditions and the like of the rough plating treatment (1) will be described.
In the present invention, the plating treatment method is preferably a roll-to-roll method, for example, from the viewpoint of mass production and production cost.

Further, if the charge density (C / dm ² ), which is the product of the average current density (A / dm ² ) and the processing time (seconds), is less than 65 C / dm ² , the sufficient adhesion required by the present invention can be obtained. Becomes difficult. Further, when the charge density exceeds 220 C / dm ² , the roughened particles grow excessively, and it becomes difficult to obtain the good transmission characteristics required by the present invention. Therefore, the charge density is preferably 65 to 220 C / dm ² .

・ Fixed plating (2)
The fixed plating treatment (2) is a treatment for performing smooth covering plating on the copper foil substrate surface-treated in the roughening plating treatment (1). Specifically, the plating treatment is performed in a copper sulfate bath. Usually, this treatment is performed to prevent the coarsened particles from falling off, that is, to immobilize the roughened particles.
As the plating method, for example, from the viewpoint of mass production and production cost, a roll-to-roll method is preferable.

The composition and electrolytic conditions of the plating solution for rough plating treatment are shown below. The following conditions are a preferable example, and the type and amount of the additive and the electrolytic conditions can be appropriately changed and adjusted as necessary within a range that does not interfere with the effects of the present invention.

<Conditions for rough plating (1)>
Copper sulfate pentahydrate: 10 to 30 g / L in terms of copper (atom)
Sulfuric acid: 100-250 g / L
Anode: Lattice-shaped anode Processing speed: 5 to 15 m / min Average current density: 20 to 80 A / dm ²
Treatment time: 1.0 to 3.0 seconds Bath temperature: 30 to 50 ° C

<Conditions for fixed plating (2)>
Copper sulfate pentahydrate: 50 to 70 g / L in terms of copper (atom)
Sulfuric acid: 80-160 g / L
Processing speed: 5 to 15 m / min Current density: 1 to 5 A / dm ²
Treatment time: 1.0 to 5.0 seconds Bath temperature: 50 to 70 ° C

Further, the surface-treated copper foil of the present invention has a roughening-treated layer having a predetermined fine uneven surface shape formed by electrodeposition of roughened particles on at least one surface of the copper foil substrate, and further. On the roughening treatment layer, directly or through an intermediate layer such as a base layer containing nickel (Ni), a heat treatment treatment layer containing zinc (Zn), and a rust prevention treatment layer containing chromium (Cr). The silane coupling agent layer may be further formed. Since the thickness of the intermediate layer and the silane coupling agent layer is very thin, it does not affect the particle shape of the roughened particles on the roughened surface of the surface-treated copper foil. The particle shape of the roughened particles on the roughened surface of the surface-treated copper foil is substantially determined by the particle shape of the roughened particles on the surface of the roughened surface corresponding to the roughened surface.

Further, as a method of forming the silane coupling agent layer, for example, a silane coupling agent solution is applied directly or via an intermediate layer on the uneven surface of the roughened surface of the surface-treated copper foil, and then air-dried ( Examples thereof include a method of forming by natural drying) or heating and drying. When the water in the solution evaporates, the applied coupling agent solution forms a silane coupling agent layer, so that the effect of the present invention is fully exhibited. Heat drying at 50 to 180 ° C. is preferable in that the reaction between the silane coupling agent and the copper foil is promoted.

The silane coupling agent layer is any one of epoxy-based silane, amino-based silane, vinyl-based silane, methacrylic-based silane, acrylic-based silane, styryl-based silane, ureido-based silane, mercapto-based silane, sulfide-based silane, and isocyanate-based silane. It preferably contains more than a seed.

As another embodiment, it is selected from a Ni-containing base layer, a Zn-containing heat-resistant treatment layer, and a Cr-containing rust preventive treatment layer between the roughening treatment layer and the silane coupling agent layer. It is preferable to have at least one intermediate layer.

In the base layer containing Ni, for example, when copper (Cu) in the copper foil substrate or the roughening treatment layer diffuses to the resin substrate side, copper damage may occur and the adhesion may decrease. It is preferably formed between the roughening treatment layer and the silane coupling agent layer. The Ni-containing base layer is preferably formed of at least one selected from nickel (Ni), nickel (Ni) -phosphorus (P), and nickel (Ni) -zinc (Zn).

The heat-resistant treatment layer containing Zn is preferably formed when it is necessary to further improve the heat resistance. The heat-resistant treatment layer containing Zn is, for example, zinc or an alloy containing zinc, that is, zinc (Zn) -tin (Sn), zinc (Zn) -nickel (Ni), zinc (Zn) -cobalt (Co). , Zinc (Zn) -Copper (Cu), Zinc (Zn) -Chrome (Cr) and Zinc (Zn) -Vanadium (V) can be formed with an alloy containing at least one zinc. preferable.

The rust preventive treatment layer containing Cr is preferably formed when it is necessary to further improve the corrosion resistance. Examples of the rust preventive treatment layer include a chrome layer formed by chrome plating and a chromate layer formed by chromate treatment.

When all of these three layers are formed, the above-mentioned base layer, heat-resistant treatment layer, and rust-prevention treatment layer are preferably formed on the roughening treatment layer in this order, and the application and purpose. Either one layer or only two layers may be formed depending on the characteristics to be applied.

[Preparation of surface-treated copper foil]
The method for producing the surface-treated copper foil of the present invention is summarized below.
In the present invention, it is preferable to prepare the surface-treated copper foil according to the following forming steps (S1) to (S5).
(S1) Step of Forming Roughening Treatment Layer A roughening treatment layer having a fine uneven surface is formed on a copper foil substrate by electrodeposition of roughened particles.
(S2) Substrate Formation Step A Ni-containing underlayer is formed on the roughening treatment layer, if necessary.
(S3) Step of Forming Heat-Resistant Treatment Layer A heat-resistant treatment layer containing Zn is formed on the roughening treatment layer or the base layer, if necessary.
(S4) Forming Step of Anti-corrosion Treatment Layer A rust-prevention treatment layer containing Cr is formed on the roughening treatment layer and / or the heat-resistant treatment layer formed on the roughening treatment layer if necessary. To do.
(S5) Step of Forming Silane Coupling Agent Layer An intermediate layer in which a silane coupling agent layer is directly formed on the roughened treatment layer, or at least one layer of a base layer, a heat resistant treatment layer and a rust prevention treatment layer is formed. A silane coupling agent layer is formed through.

<Copper laminated board and printed wiring board>
The surface-treated copper foil of the present invention is suitably used for producing a copper-clad laminate. Such a copper-clad laminate is suitably used for manufacturing a printed wiring board having excellent high adhesion and high-frequency transmission characteristics, and exhibits excellent effects. In particular, the surface-treated copper foil of the present invention is suitable when used as a printed wiring board for a high frequency band of, for example, 1 GHz or more, preferably 10 GHz to 40 GHz band.

Further, the copper-clad laminate can be formed by a known method using the surface-treated copper foil of the present invention. For example, in a copper-clad laminate, a surface-treated copper foil and a resin base material (insulating substrate) are laminated and bonded so that the roughened surface (sticking surface) of the surface-treated copper foil and the resin base material face each other. Manufactured by Examples of the resin base material include a flexible resin substrate and a rigid resin substrate.

Further, when a copper-clad laminate is manufactured, it may be manufactured by laminating a surface-treated copper foil having a silane coupling agent layer and a resin base material by a heating press. A silane coupling agent is applied onto the resin base material, and the resin base material coated with the silane coupling agent and the surface-treated copper foil having the rust preventive treatment layer on the outermost surface are bonded together by a heat press. The produced copper-clad laminate also has the same effect as that of the present invention.

Further, the printed wiring board can be formed by a known method using the copper-clad laminate.

Although the embodiment of the present invention has been described above, the above embodiment is only an example of the present invention. The present invention includes all aspects included in the concept of the present invention and the scope of claims, and can be variously modified within the scope of the present invention.

Hereinafter, the present invention will be described in more detail based on examples, and the following is an example of the present invention.

(Manufacturing example: Preparation of copper foil substrate)
A roll-shaped electrolytic copper having a thickness of 12 μm under the following electrolytic conditions using a copper sulfate electrolytic solution having the following composition using the following cathode and anode as the copper foil substrate to be the base material for roughening treatment. A foil (double-sided glossy foil) was produced.

<Cathode and anode>
Cathode: Titanium rotary drum whose roughness has been adjusted by buffing # 1000 to # 2000 Anode: Dimensional stability anode DSA (registered trademark)
<Electrolytic solution composition>
Cu: 80 g / L
H ₂ SO ₄ : 70 g / L
Chlorine concentration: 25 mg / L
(Additive)
-Sodium 3-mercapto-1-propanesulfonate: 2 mg / L
-Hydroxyethyl cellulose: 10 mg / L
-Low molecular weight glue (molecular weight 3000): 50 mg / L
<Electrolysis conditions>
Bath temperature: 55 ° C
Current density: 45A / dm ²

(Example 1)
In Example 1, the following steps [1] to [3] were performed to obtain a surface-treated copper foil. This will be described in detail below.

[1] Formation of Roughening Treatment Layer The electrolytic copper foil produced in the above production example was used as a copper foil substrate, and the M surface of the copper foil substrate was roughened and plated by a roll-to-roll method. This roughening plating treatment was performed by a two-step electroplating treatment. In the rough plating treatment (1), the following rough plating solution basic bath composition is used, the copper concentration is as shown in Table 1 below, and the treatment speed and the length ratio in the copper foil transport direction are 1: 2: 3. Whether or not multiple anodes were used (whether or not a lattice-shaped anode was used), bath temperature, average current density, processing time, and charge density were as shown in Table 1 below. Further, in the fixed plating treatment (2), the following fixed plating solution composition was used, and the current density, treatment speed, treatment time, and charge density were as shown in Table 1 below.

<Basic bath composition of roughened plating solution>
H ₂ SO ₄ : 150 g / L

<Fixed plating solution composition, bath temperature>
Cu: 60 g / L
H ₂ SO ₄ : 120 g / L
Bath temperature: 60 ° C

[2] Formation of metal-treated layer Next, the surface of the roughened-treated layer formed in [1] above is metal-plated in the order of Ni, Zn, and Cr under the following conditions to form a metal-treated layer (intermediate layer). Was formed.

<Ni plating conditions>
Ni: 40g / L
H ₃ BO ₃ : 5 g / L
Bath temperature: 20 ° C
pH: 3.6
Current density: 0.2A / dm ²
Processing time: 10 seconds

<Zn plating conditions>
Zn: 2.5 g / L
NaOH: 40 g / L
Bath temperature: 20 ° C
Current density: 0.3A / dm ²
Processing time: 5 seconds

<Cr plating conditions>
Cr: 5g / L
Bath temperature: 30 ° C
pH: 2.2
Current density: 5A / dm ²
Processing time: 5 seconds

[3] Formation of silane coupling agent layer Finally, 3-glycidoxy having a concentration of 0.2% by mass is placed on the metal-treated layer (particularly, the outermost Cr plating layer) formed in [2] above. An aqueous solution of propyltrimethoxysilane was applied and dried at 100 ° C. to form a silane coupling agent layer.

(Examples 2 to 9 and Comparative Examples 1 to 6)
In Examples 2 to 9 and Comparative Examples 1 to 6, the conditions of the roughening plating treatment (1) and the fixed plating treatment (2) in the roughening treatment layer forming step [1] are as shown in Table 1 above. A surface-treated copper foil was obtained in the same manner as in Example 1 except that.

[Evaluation]
The characteristics of the surface-treated copper foils according to the above Examples and Comparative Examples were evaluated as shown below.
The evaluation conditions for each characteristic are as follows, and unless otherwise specified, each measurement was performed at room temperature (20 ° C ± 5 ° C). The results are shown in Table 2.

[Cross section observation]
The cross-sectional observation of the surface-treated copper foil was carried out by image analysis in the following procedure steps (i) to (iii).
First, (i) a test piece is cut out from the obtained surface-treated copper foil at a size of 5 mm square, cut from the roughened surface side of the surface-treated copper foil perpendicular to the roughened surface, and the cut surface is cut by an ion milling apparatus (i). Using "IM4000" manufactured by Hitachi High-Technologies Corporation), precision polishing is performed for 30 minutes under the conditions of stage mode C1 (swing angle: ± 15 °, swing speed: 6 reciprocations / min) and acceleration voltage of 6 kV. Using a scanning electron microscope (“SU8020” manufactured by Hitachi High-Technologies Corporation), the processed surface of the surface-treated copper foil exposed on the surface of the prepared measurement sample is subjected to an acceleration voltage of 3 kV from the direction perpendicular to the processed surface. Observe the secondary electron image of 10,000 times, and prepare a cross-sectional photograph (SEM image, length 9.5 μm × width 12.5 μm) near the roughened surface.

Next, (ii) the cross-sectional photograph is subjected to image processing that emphasizes the contour of the roughened particles using image editing software (“Real World Paint”), the contour line of the cross-sectional shape is extracted, and finally. Only the contour line of the cross-sectional shape in the same processed cross section is extracted. Then, (iii) using image measurement software (PhotoRuler), the particle height (h) and particle width (w) of the coarsened particles in the contour line, and the coarsened particles existing in an arbitrary observation field (observation target). The number of particles) is measured respectively. Further, for the roughened particles that correspond to the above-mentioned roughened particles (p), the number of roughened particle nodes and the shortest distance between roots are further measured.

Based on the above measured values, the average value of the particle height (h), the particle width (w), and the ratio (h / w) of the particle height (h) to the particle width (w) of the roughened particles, and the coarseness. The linear density (d) of the chemical particles and the number of the specific roughened particles (P) are obtained respectively.

The analysis up to this point is performed for the same surface-treated copper foil at 6 arbitrary cross sections and a total field of view of 75 μm in the width direction. Then, based on each measured value of a total of 6 cross-sectional photographs, the average value of the particle height (h) of the roughened particles, the average value of the particle width (w), and the particle height (h) with respect to the particle width (w). The average value of the ratio (h / w) and the average value of the linear density (d) were calculated, and each of these average values was used as the measured value of the surface-treated copper foil as the observation target. Further, the number of the specified roughened particles (P) observed in each cross-sectional photograph was totaled, and this value was taken as the measured value of the surface-treated copper foil as the observation target. Table 2 shows the measured values of the surface-treated copper foils of each Example and Comparative Example.

[Expanded area ratio (Sdr)]
The developed area ratio (Sdr) is measured by measuring the surface shape of the roughened surface of the surface-treated copper foil using a white light interference type optical microscope (WykoContourGT-K, manufactured by BRUKER), and further analyzing the shape. Was done by.
For surface shape measurement, a high-density CCD camera is used in the VSI measurement method, the zoom lens magnification is 1x, the objective lens magnification is 50x, the measurement area is 96.1 μm × 72.1 μm, the light source is a white light source, and Lateral Sample is 0. The measurement was performed under the conditions of 075 μm, 1 time speed, 10 μm Backscan, 10 μm Lens, and 3% Thrashold.
Further, as shape analysis, (1) Terms Removal (Cylinder and Tilt), (2) DataRestore (Metamode: legacy, iterations: 5, RestoreEdit: not selected), (3) Cutoff frequency by Fourier transform 62.5 mm ^-1. After filtering in the order of the high-frequency path Gaussian filter, data processing was performed.
The developed area ratio (Sdr) was measured at any 10 points on the roughened surface of the surface-treated copper foil for one surface-treated copper foil, and the obtained values (N = 10) were averaged. The developed area ratio (Sdr) of the surface-treated copper foil was used.

[Evaluation of powder drop]
First, a test piece was cut out from the surface-treated copper foil at a size of about 80 mm × 50 mm square, and fixed on a plastic plate having a flat surface with the roughened surface facing up. Next, two types of filter paper (manufactured by ADVANTEC) specified in JIS P3801-1995 were superposed on the roughened surface, and a weight having a weight of 250 g was further placed on the filter paper. At this time, the contact surface between the filter paper and the weight was circular with a diameter of 30 mm.
Next, the filter paper was pulled horizontally by 100 mm in 5 seconds with the weight on it. Then, the weight was removed, and the filter paper on the surface-treated copper foil was gently peeled off in the vertical direction to collect the filter paper.
The filter paper was checked with the naked eye, and if the adhesion of copper particle powder was not confirmed, it was evaluated as "no", and if the adhesion of copper particle powder was confirmed, it was evaluated as "yes". I evaluated it.

[Evaluation of transmission characteristics]
As an evaluation of the transmission characteristics, the transmission loss in the high frequency band was measured. Details will be described below.
A substrate for measuring transmission characteristics was prepared by laminating a polyphenylene ether-based low dielectric constant resin base material (Megtron 6, manufactured by Panasonic Corporation, thickness 60 μm) and a surface-treated copper foil. The structure of the substrate was a stripline structure, the conductor length was 400 mm, the conductor thickness was 18 μm, the conductor width was 0.14 mm, the total thickness was 0.39 mm, and the characteristic impedance was adjusted to 50 Ω. Further, the surface-treated copper foil and the resin base material are bonded by stacking the surface-treated copper foil so that the roughened surface faces the resin base material and pressing the surface-treated copper foil at a surface pressure of 3.1 MPa and 200 ° C. for 2 hours. Carried out.
Regarding the substrate for measuring the transmission characteristics, the transmission loss at 40 GHz was measured using a vector network analyzer E8364C (KEYSIGHT TECHNOLOGIES).
The measured value of the transmission loss means that the smaller the absolute value, the smaller the transmission loss and the better the transmission characteristics. Using the obtained measured values as an index, the transmission characteristics were evaluated based on the following evaluation criteria.
A: Absolute value of transmission loss at a conductor length of 400 mm at 40 GHz is less than 32 dB B: Absolute value of transmission loss at a conductor length of 400 mm at 40 GHz is 32 dB or more and 36 dB or less C: Transmission loss at a conductor length of 400 mm at 40 GHz Absolute value is greater than 36 dB

[Evaluation of adhesion]
As an evaluation of adhesion, a peeling test was performed based on JIS C 6681: 1996. Details will be described below.
Surface-treated The roughened surface of the copper foil is made by stacking two polyphenylene ether-based low-dielectric-constant resin substrates (Megtron 7, manufactured by Panasonic Corporation, thickness 60 μm) on one side under the conditions of a surface pressure of 3.5 MPa and 200 ° C. A copper-clad laminate was prepared by laminating by pressing for 2 hours. The copper foil portion (surface-treated copper foil) of the obtained copper-clad laminate was masked with a 10 mm width tape. After performing copper chloride etching on this copper-clad laminate, the tape was removed to prepare a circuit wiring board having a width of 10 mm. Peeling strength when the 10 mm wide circuit wiring part (copper foil part) of this circuit wiring board is peeled from the resin substrate at a speed of 50 mm / min in the 90 degree direction using a Tensilon tester manufactured by Toyo Seiki Seisakusho Co., Ltd. Was measured. Adhesion (normal adhesion) was evaluated based on the following evaluation criteria using the obtained measured values as an index.
<Evaluation criteria for adhesion>
A: Peeling strength is 0.60 kN / m or more B: Peeling strength is 0.50 kN / m or more and less than 0.60 kN / m C: Peeling strength is less than 0.50 kN / m

[Evaluation of heat resistance]
As an evaluation of heat resistance, the presence or absence of blister on the copper foil-resin base material interface after reflow was evaluated. Details will be described below.
First, surface-treated copper foil is laminated on both sides of two polyphenylene ether-based low-dielectric-constant resin base materials (Megtron 7, manufactured by Panasonic Corporation, thickness 60 μm) so that the roughened surfaces face the resin base material. , The surface pressure was 3.5 MPa and the pressure was 200 ° C. for 2 hours to bond them together to prepare a double-sided copper-clad laminate.
The obtained copper-clad laminate was cut into three pieces having a size of 100 mm × 100 mm, and this was used as a test piece.
Next, the prepared test piece was passed through a reflow furnace 10 times at a top temperature of 260 ° C. under heating conditions for 10 seconds.
The surface of the test piece on the copper foil side after heating under the above conditions was observed to check for the presence or absence of blisters. Those with blister confirmed from the surface were cut at the center of the blister region, and the cross section was observed with a microscope to confirm whether there was delamination between the copper foil and the resin substrate. For the test pieces in which delamination was observed, it was determined that blisters at the copper foil-resin base material interface had occurred. From the above observation results, the heat resistance was evaluated based on the following evaluation criteria.
<Evaluation criteria for heat resistance>
A: Of the above three test pieces, no blisters at the copper foil-resin base material interface were generated.
B: Of the above three test pieces, one of the test pieces had blister on the copper foil-resin base material interface.
C: Of the above three test pieces, two or more test pieces had blister on the copper foil-resin base material interface.

[Evaluation of substrate moisture resistance reliability]
As an evaluation of the substrate moisture resistance reliability, the presence or absence of blisters between the resin base material and the resin base material after the PCT (Pressure Cooker Test) and the solder float was evaluated. Details will be described below.
First, a double-sided copper-clad laminate was produced by the same method as described in [Evaluation of heat resistance] above. The copper foil on both sides of the double-sided copper-clad laminate is removed by etching the entire surface, and a polyphenylene ether-based low dielectric constant resin base material (Megtron 7, manufactured by Panasonic Corporation, thickness 60 μm) is applied to both sides after etching. Stack one by one, and stack one surface-treated copper foil on each surface of the stacked resin base material so that the roughened surfaces face each other, and press for 2 hours under the conditions of surface pressure of 3.5 MPa and 200 ° C. As a result, the resin base materials and the resin base materials and the copper foil were bonded together to obtain a laminated body. Further, the copper foils on both sides of the laminated body were removed by etching the entire surface, and finally, a resin base material laminated body in which four layers of resin base materials were stacked was obtained.
The resin base material laminate was cut into three pieces having a size of 100 mm × 100 mm, and this was used as a test piece.
Next, using the prepared test piece, PCT (Pressure Cooker Test) was performed under the following conditions, and within 1 hour after taking out, a solder float test was performed under the following conditions.
The PCT was carried out using a high acceleration life test HAST device (PC-422R8, manufactured by Hirayama Seisakusho Co., Ltd.) under the conditions of a temperature of 121 ° C., a humidity of 100% RH, and 48 hours.
Further, in the solder float test, the operation of floating the test piece in a solder bath heated to 288 ° C. for 10 seconds and then leaving it at room temperature for 10 seconds was repeated 10 times.
The surface of the test piece after the solder float test was observed, and the presence or absence of blisters was visually determined. From the observation results, the moisture resistance and reliability of the substrate were evaluated based on the following evaluation criteria.
<Evaluation criteria for substrate moisture resistance reliability>
A: Of the above three test pieces, no blisters were generated.
B: Of the above three test pieces, one of the test pieces had blisters.
C: Of the above three test pieces, two or more test pieces had blisters.

[Comprehensive evaluation]
All of the above powder removal, transmission characteristics, adhesion, heat resistance, and substrate moisture resistance reliability were integrated, and a comprehensive evaluation was performed based on the following evaluation criteria. In this example, S, A and B were set as pass levels in the comprehensive evaluation.
<Evaluation criteria for comprehensive evaluation>
S (best): There is no powder falling off, and all evaluations of transmission characteristics, adhesion, heat resistance, and substrate moisture resistance reliability are A evaluations.
A (excellent): There is no powder falling off, there is no C evaluation in all the evaluations of transmission characteristics, adhesion, heat resistance and substrate moisture resistance reliability, and any one of these evaluations is B evaluation.
B (Good): There is no powder falling, there is no C evaluation in all evaluations of transmission characteristics, adhesion, heat resistance and substrate moisture resistance reliability, and there is a B evaluation in any two or more of these evaluations. ..
C (Failure): There is a C rating based on one or more evaluations of transmission characteristics, adhesion, heat resistance, and substrate moisture resistance reliability.

As shown in Table 2, in the surface-treated copper foils of Examples 1 to 9, when the cross section thereof was observed by SEM, the roughened surface was the particle height (h) of the roughened particles in the region of 75 μm in the width direction. ) Is 0.8 to 2.0 μm, and the ratio (h / w) of the particle height (h) to the particle width (w) of the roughened particles is 1.5 to 4.5. Yes, since it is controlled so that 1 to 60 specific roughened particles (P) are present, there is no powder falling off, and excellent transmission characteristics, adhesion, and heat resistance are particularly good when used in a conductor circuit of a printed wiring board. And it was confirmed that the moisture resistance and reliability of the substrate can be realized.

On the other hand, in the surface-treated copper foils of Comparative Examples 1 to 6, the average value of the particle heights (h) of the roughened particles in the region of 75 μm in the width direction is 0.8 to 2.0 μm on the roughened surface. , The average value of the ratio (h / w) of the particle height (h) to the particle width (w) of the roughened particles is 1.5 to 4.5, and 1 to 60 specific roughened particles (P). Since it does not satisfy at least one of the existing ones, it has one or more of transmission characteristics, adhesion, heat resistance, substrate moisture resistance reliability, and powder removal as compared with the surface-treated copper foils of Examples 1 to 9. It was confirmed that the characteristics were inferior in the evaluation.

Claims (5)

A surface-treated copper foil having a surface-treated film containing a roughened-treated layer in which roughened particles are formed on at least one surface of the copper foil substrate.
When observing the cross section of the surface-treated copper foil with a scanning electron microscope (SEM), in a region of 75 μm in the width direction of the surface-treated film,
The average value of the particle height (h) of the roughened particles is 0.8 to 2.0 μm.
The average value of the ratio (h / w) of the particle height (h) to the particle width (w) of the roughened particles is 1.5 to 4.5.
A surface-treated copper foil in which 1 to 60 roughened particles (P) satisfying the following requirements (I) to (IV) are present among the roughened particles.
-Requirement (I): The particle height (h) of the roughened particles is 1.5 to 3.5 μm.
-Requirement (II): The ratio (h / w) of the particle height (h) to the particle width (w) of the roughened particles is 2.5 to 15.
-Requirement (III): The number of nodes of the roughened particles is 10 to 25.
-Requirement (IV): The shortest root-to-root distance between the roughened particles and other roughened particles having a particle height of 1.5 μm or more closest to the roughened particles is 0.7 to 10.0 μm. The surface-treated copper foil according to claim 1, wherein the linear density (d) of the roughened particles is 1.0 to 1.8 particles / μm. The surface-treated copper foil according to claim 1 or 2, wherein the developed area ratio (Sdr) measured by a three-dimensional white interference type microscope on the surface of the surface-treated film is 300 to 380%. A copper-clad laminate formed by using the surface-treated copper foil according to any one of claims 1 to 3. A printed wiring board formed by using the copper-clad laminate according to claim 4.