JP6294862B2 - Surface-treated copper foil for printed wiring board, copper-clad laminate for printed wiring board, and printed wiring board - Google Patents

Description

  The present invention relates to a surface-treated copper foil for a printed wiring board. Moreover, this invention relates to the copper clad laminated board for printed wiring boards and the printed wiring board using the said surface treatment copper foil for said printed wiring boards.

  In recent years, with the advancement of high performance and high functionality of computers and information communication devices and the progress of networking, it is necessary to transmit large volumes of information at higher speed. For this reason, transmitted signals tend to have higher frequencies, and printed wiring boards that suppress transmission loss of high-frequency signals are required. For the production of printed wiring boards, copper foil and an insulating base material (resin base material) are usually laminated, and this is heated and pressed to produce a copper-clad laminate, which is bonded to the copper-clad laminate. A conductor circuit is formed by using. The transmission loss when a high-frequency signal is transmitted to this conductor circuit (high-frequency transmission) is related to three factors: conductor loss, dielectric loss, and radiation loss.

  The conductor loss is caused by the skin resistance of the conductor circuit. When a high-frequency signal is transmitted to a conductor circuit formed using a copper-clad laminate, a skin effect phenomenon occurs. That is, when an alternating current is passed through the conductor circuit, the magnetic flux changes and a back electromotive force is generated at the center of the conductor circuit. As a result, it is difficult for current to flow through the center of the conductor. The phenomenon that increases. This skin effect phenomenon causes so-called skin resistance to reduce the effective cross-sectional area of the conductor. The thickness (skin depth) of the skin portion through which current flows is inversely proportional to the square root of the frequency.

In recent years, high frequency compatible devices exceeding 20 GHz have been developed. When a high-frequency signal having a frequency in the GHz band is transmitted to the conductor circuit, the skin depth is about 2 μm or less, and the current flows only on the surface layer of the conductor. Therefore, if the surface roughness of the copper foil is large in the copper clad laminate used for such high frequency equipment, the transmission path of the conductor formed by the copper foil (that is, the transmission path of the skin portion) becomes long and transmission loss is reduced. To increase. Therefore, it is desired to reduce the surface roughness of the copper foil of the copper clad laminate used for high-frequency equipment.
On the other hand, copper foil used for printed wiring boards generally forms a roughened layer (layer on which roughened particles are formed) on the surface using a technique such as electroplating or etching, and has a physical effect ( The adhesive force with the resin base material is enhanced by the anchor effect). However, if the roughened particles formed on the surface of the copper foil are increased in order to effectively increase the adhesive strength with the resin base material, the transmission loss increases as described above.

The dielectric loss is caused by the dielectric constant and dielectric loss tangent of the resin base material. When a pulse signal is passed through a conductor circuit, the electric field around the conductor circuit changes. When the period (frequency) at which the electric field changes approaches the relaxation time of polarization of the resin base material (the moving time of the charged body that generates polarization) (that is, when the frequency is increased), the electric field change is delayed. In such a state, molecular friction occurs inside the resin, heat is generated, and transmission loss occurs. In order to suppress this dielectric loss, a resin with a small amount of a large polar substituent or a resin without a large polar substituent is adopted as the resin base of the copper-clad laminate, and the resin base is polarized due to a change in electric field. It is necessary to make it difficult to produce.
On the other hand, the copper foil used for the printed wiring board increases the chemical adhesive force with the resin base material by treating the copper foil surface with a silane coupling agent in addition to the formation of the roughening treatment layer. Is also done. In order to improve the chemical adhesion between the silane coupling agent and the resin base material, it is necessary that the resin base material has a substituent having a certain degree of polarity. When a low dielectric substrate with a reduced amount of groups is used, the chemical adhesive strength is reduced, and it is difficult to ensure sufficient adhesion between the copper foil and the resin substrate.

  As described above, in the copper-clad laminate, suppression of transmission loss and improvement in adhesion (adhesion) between the copper foil and the resin base material are in a trade-off relationship with each other.

In recent years, high-frequency compatible printed wiring boards have been deployed in fields where higher reliability is required. For example, for use as a printed wiring board for mobile communication such as in-vehicle use, high reliability that can withstand use in harsh environments is required. A copper-clad laminate that meets this requirement requires a high degree of adhesion between the copper foil and the resin substrate.
Technological development is underway to meet these requirements. For example, in Patent Document 1, roughened particles are attached to a copper foil, a roughened surface having a surface roughness Rz of 1.5 to 4.0 μm and a brightness value of 30 or less is formed. A surface-treated copper foil in which the protrusions formed from the roughened particles have a specific height and width is described in which the surface-treated copper foil is distributed substantially evenly in density. It is described that the adhesion to a resin base material for a high-frequency circuit board is improved.

In a small electronic device such as a smartphone or a tablet PC, a flexible printed wiring board (hereinafter referred to as FPC) is adopted because of easy wiring and light weight. In recent years, with the increase in functionality of these small electronic devices, the speed of signal transmission has increased, and impedance matching (matching of output resistance and input resistance) of FPC has become important. In order to realize impedance matching for an increase in signal transmission speed, a resin base material (typically polyimide) serving as a base for an FPC is thickened.
The FPC is subjected to predetermined processing such as being bonded to a liquid crystal substrate or mounting an IC chip. The alignment at the time of this processing is performed using a positioning pattern that is visible through the portion of the resin base material from which the copper foil has been removed by etching as an index. Therefore, in the above alignment, the permeability (visibility) of the resin base material is important. The transparency of this resin substrate is usually evaluated and managed using the total light transmittance in the visible light region and haze (haze value). In recent years, the thickness of the resin base material and the alignment process have been diversified, and the level of permeability required for the resin base material after etching has increased. In addition to the characteristics of the resin itself, the surface shape of the copper foil bonded to the resin substrate greatly affects the permeability of the resin substrate after etching.
A resin base material having flexibility such as polyimide and liquid crystal polymer is laminated with a copper foil under high temperature and high pressure conditions. At that time, since the resin enters the base of the roughened particles formed on the roughened surface of the copper foil, the larger the roughened particles, the deeper the unevenness transferred to the resin. The transmitted light tends to be scattered and tends to be inferior in transparency.

  Further, Patent Document 2 relating to FPC includes a rust-proofing layer made of a nickel-zinc alloy on an adhesion surface bonded to an insulating layer, and the surface roughness (Rz) of the adhesion surface is 0.05 to 1.5 μm. An FPC suitable for a chip-on-film (COF) type having an electrolytic copper foil having a specular gloss of 250 or more at an incident angle of 60 ° is described, and the FPC exhibits excellent light transmittance, and the copper foil and the resin It is described that the adhesion to the substrate is also good.

  Further, in Patent Document 3, roughened particles are formed by roughening treatment, the average roughness Rz of the roughened surface is 0.5 to 1.3 μm, the glossiness is 4.8 to 68, and roughened particles. A surface-treated copper foil having a ratio A / B of 2.00 to 2.45 of the surface area A and the area B obtained when the roughened particles are planarly viewed from the copper foil surface side is described. The copper clad laminate formed by laminating the treated copper foil and the resin substrate has good resin transparency after the copper foil is removed by etching, and good adhesion between the copper foil and the resin. Have been described.

Japanese Patent No. 4833556 Japanese Patent No. 4090467 Japanese Patent No. 5497808

  The surface-treated copper foil described in Patent Document 1 is excellent in adhesion with a high-frequency resin substrate, but the copper-clad laminate using this surface-treated copper foil has a high transmission loss in the high-frequency band of the GHz band, The advanced requirements for high frequency printed circuit boards have not been fully met.

  In addition, the electrolytic copper foil used in the FPC described in Patent Document 2 is not roughened, and achieves a high degree of adhesion with a resin substrate required for printed wiring boards other than COF. It has not been done.

  In addition, the surface-treated copper foil described in Patent Document 3 cannot obtain sufficient adhesion with a resin substrate when a low dielectric substrate is used as the resin substrate.

  The present invention provides a printed wiring board that has a high transmission loss even when transmitting a high frequency signal in the GHz band, has high adhesion to a resin base material, is excellent in durability, and has excellent visibility. It is an object to provide a surface-treated copper foil for a printed wiring board that can be obtained. Moreover, this invention makes it a subject to provide the copper clad laminated board for printed wiring boards and the printed wiring board (circuit board) using the said surface-treated copper foil for printed wiring boards.

The above-mentioned problems of the present invention are solved by the following means.
[1]
A surface-treated copper foil for a printed wiring board having a silane coupling agent layer on the surface on which roughened particles are formed by roughening plating ,
On the surface of the silane coupling agent layer, the average height of the roughened particles is 0.05 μm or more and less than 0.5 μm,
A surface-treated copper foil for a printed wiring board, wherein a BET surface area ratio on the surface of the silane coupling agent layer is 1.2 or more and a fine surface coefficient Cms is 2.0 or more and less than 8.0.
[2]
The surface-treated copper foil for printed wiring board according to [1], wherein the average height of the roughened particles is 0.05 μm or more and less than 0.3 μm on the surface of the silane coupling agent layer.
[3]
Of the silane coupling agent layer surface, L ^* a ^* b ^* Table L ^* is less than 40 or more 60 in the color system, [1] or a printed circuit board for surface-treated copper foil according to [2].
[4]
The surface on which the roughened particles are formed has a metal treatment layer having at least one metal selected from chromium, iron, cobalt, nickel, copper, zinc, molybdenum, and tin, or chromium, iron The printed wiring board according to any one of [1] to [3], comprising a metal-treated layer having an alloy composed of two or more metals selected from cobalt, nickel, copper, zinc, molybdenum, and tin Surface treated copper foil.
[5]
The surface treatment for a printed wiring board according to any one of [1] to [4], wherein the amount of Si element contained in the silane coupling agent layer is 0.5 μg / dm ² or more and less than 15 μg / dm ^2. Copper foil.
[6]
The silane coupling agent is at least one functional group selected from an epoxy group, an amino group, a vinyl group, a (meth) acryloyl group, a styryl group, a ureido group, an isocyanurate group, a mercapto group, a sulfide group, and an isocyanate group. The surface-treated copper foil for printed wiring boards according to any one of [1] to [5].
[7]
The copper clad laminated board for printed wiring boards by which the resin layer is laminated | stacked on the said silane coupling agent layer surface of the surface-treated copper foil for printed wiring boards of any one of [1]-[6].
[8]
The printed wiring board using the copper clad laminated board for printed wiring boards as described in [7].

The surface-treated copper foil for a printed wiring board according to the present invention is used for a conductor circuit of a printed wiring board, so that transmission loss when transmitting a high-frequency signal in the GHz band is suppressed to a high level. It is possible to obtain a printed wiring board having high adhesion to the substrate, excellent durability, and excellent visibility.
The copper-clad laminate for a printed wiring board according to the present invention is used as a substrate for a printed wiring board, so that transmission loss when transmitting a high-frequency signal in the GHz band is suppressed to a high level. It is possible to obtain a printed wiring board having high adhesion and excellent durability and excellent visibility.
The printed wiring board of the present invention is highly suppressed in transmission loss when transmitting a high frequency signal in the GHz band, has high adhesion between the copper foil and the resin base material, is excellent in durability, and is also visible. Excellent.

It is explanatory drawing which shows an example of the measuring method of the height of roughening particle | grains. It is explanatory drawing which shows an example of the measuring method of the height of roughening particle | grains.

  Preferred embodiments of the surface-treated copper foil for printed wiring board of the present invention will be described below.

[Surface-treated copper foil for printed wiring boards]
The surface-treated copper foil for printed wiring boards of the present invention (hereinafter referred to as “surface-treated copper foil of the present invention”) has a surface on which roughened particles are formed (a surface on which an antiseptic metal is further adhered if necessary). Treated with a coupling agent (that is, having a silane coupling agent layer on the surface on which the roughened particles are formed), and on the surface of the silane coupling agent layer (surface treated copper foil outermost surface) The average height of the activated particles is 0.05 μm or more and less than 0.5 μm, the BET surface area ratio of the silane coupling agent layer surface is 1.2 or more, and the fine surface area coefficient of the silane coupling agent layer surface (Cms) is 2.0 or more and less than 8.0. In the surface-treated copper foil of the present invention, the average height of the roughened particles measured on the surface of the silane coupling agent layer is 0.05 μm or more and less than 0.5 μm, and the BET surface area ratio of the surface Is 1.2 or more and the surface Cms is 2.0 or more and less than 8.0 is simply referred to as “roughening surface”. The roughened surface is preferably entirely covered with a silane coupling agent, but as long as the effects of the present invention are achieved, a portion of the roughened surface may not be covered with the silane coupling agent. (In other words, as long as the effect of the present invention is exhibited, a film defect may be generated in a part of the silane coupling agent layer on the roughened surface, and such a form also has “a silane coupling agent layer” in the present invention. Included in the form).
The surface-treated copper foil of the present invention only needs to have at least one roughened surface, and both surfaces may be roughened surfaces. The surface-treated copper foil of the present invention is usually in a form in which only one surface is a roughened surface.

In the surface-treated copper foil of the present invention, the roughened surface has a large BET surface area ratio of 1.2 or more although the average height of the roughened particles is as low as less than 0.5 μm. Therefore, when the surface-treated copper foil and the resin layer are laminated through the roughened surface, and the copper-clad laminate is produced, the anchor effect of the roughened particles and the large surface area are combined, Adhesion between the copper foil and the resin layer is highly enhanced, and a copper-clad laminate having excellent heat resistance can be obtained. Further, the roughened surface has an average height of roughened particles as low as less than 0.5 μm, and the influence of the presence of roughened particles on the length of the transmission path can be reduced. Therefore, transmission loss can be effectively suppressed even when a high-frequency signal in the GHz band is transmitted to a conductor circuit using the copper-clad laminate.
So far, there is no known method for increasing the BET surface area ratio to 1.2 or more while forming small rough particles having an average height of less than 0.5 μm on the copper foil surface. Under such circumstances, the present inventors employ the specific roughening plating treatment conditions described later to have roughened particles having an average height of 0.05 μm or more and less than 0.5 μm, and a BET surface area ratio of 1. The present invention was completed by successfully producing two or more copper foil surfaces.
From the viewpoint of more effectively reducing transmission loss while maintaining high adhesion with the resin base material, the average height of the roughened particles on the roughened surface is preferably 0.05 μm or more and less than 0.5 μm. 0.05 μm or more and less than 0.3 μm is more preferable.
In the present invention, the roughened particles are preferably formed uniformly (homogeneously) on the entire roughened surface. The average height of the roughened particles is measured by the method described in Examples described later.

The BET surface area ratio is calculated based on the surface area measurement method by the BET method. That is, the BET surface area ratio is obtained by adsorbing a gas molecule whose adsorption occupation area is known on the sample surface, obtaining the surface area of the sample (BET measurement surface area) based on the adsorption amount, and unevenness on the sample surface from the BET measurement surface area. This is the ratio of the value obtained by subtracting the surface area (sample cut-out area) when it is assumed to be absent to the sample cut-out area, and is measured by the method described in the examples described later.
In the surface-treated copper foil of the present invention, the larger the value of the BET surface area ratio of the roughened surface, the larger the surface area. Therefore, the larger the BET surface area ratio of the roughened surface, the higher the interaction with the resin, and in combination with the anchor effect of the roughened particles, the copper foil and the resin layer when the resin layers are laminated Adhesion is improved. In the surface-treated copper foil of the present invention, the BET surface area ratio of the roughened surface is preferably 1.2 or more and 10 or less, more preferably 4 or more and 8 or less.

In the surface area measurement with a laser microscope generally used in the surface area measurement of copper foil, it is impossible in principle to measure the “shade” part where the laser beam does not reach due to the shape of the roughened particles, and it is extremely fine. It is also difficult to detect the surface area of the uneven portion with high sensitivity. For example, even if rough particles with the same height and diameter are compared with rough particles with a narrow root and rough particles that do not, the former has a larger area in close contact with the resin. In the surface area measurement by, the values are almost the same.
On the other hand, in the measurement of the surface area by the BET method, since the surface area is measured by adsorption of gas molecules, the sensitivity to fine irregularities is high, and it is possible to measure a portion that is “shadow” by laser light. Therefore, the surface area of the sample on which the roughened particles are formed can usually be measured with higher accuracy than when a laser microscope is used.
The present inventors have succeeded in further increasing the ratio of the surface area of “shadows” and fine irregularities that cannot be measured with a laser microscope by applying a specific roughening plating process described later. Thereby, while suppressing the average height of the roughened particles and effectively suppressing the transmission loss when transmitting a high-frequency signal, it is possible to greatly improve the adhesion with the resin base material, and after etching The inventors have found that the visibility of the resin base material can be maintained well, and have completed the present invention.

The Cms is the ratio of the surface area ratio measured by the BET method to the surface area ratio measured by the laser microscope, and the ratio of the surface area of the “shadow” portion and the fine uneven portion that cannot be measured by the laser microscope is quantified. Is. Details of the calculation method of Cms are as described in the examples described later. In the surface-treated copper foil of the present invention, Cms of the roughened surface is 2.0 or more and less than 8.0. The average height of the roughened particles on the roughened surface and the BET surface area ratio of the roughened surface are within the range defined by the present invention, and the Cms of the roughened surface is 2.0 or more and less than 8.0. Thus, the visibility (transmittance) of the resin after etching can be maintained well while the adhesion between the surface and the resin base material is highly enhanced. Cms is preferably 2.5 or more and less than 5.0.
The surface area measured by the laser microscope and the surface area measured by the BET method have different surface area measurement principles, and Cms may be less than 1 depending on the shape of the roughened surface.

In the surface-treated copper foil of the present invention, the lightness index L ^* (Lightness) of the roughened surface is preferably 40 or more and less than 60, and more preferably 40 or more and less than 55. If the surface is a brown-brown to black treated surface (a surface on which an alloy or copper oxide is formed) as in the so-called blackening treatment, L ^* is small and transmission loss tends to increase. On the other hand, when the shape of the roughened particles is rounded, L ^* increases and the adhesion to the resin base material tends to decrease. L ^* is measured by the method described in Examples described later.

In the surface-treated copper foil of the present invention, the surface on which the roughened particles are formed before the silane coupling agent treatment is chromium (Cr), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu ), Zinc (Zn), molybdenum (Mo), and tin (Sn), or a metal treatment layer having at least one metal selected from chromium, iron, cobalt, nickel, copper, zinc, molybdenum, And a metal treatment layer having an alloy composed of two or more metals selected from tin. This metal treatment layer has a metal treatment layer having at least one metal selected from nickel, zinc, and chromium, or an alloy made of two or more metals selected from nickel, zinc, and chromium. It is more preferable to have a metal treatment layer.
The copper clad laminate or printed wiring board in which the surface-treated copper foil of the present invention is used is often subjected to heat in the production process, such as an adhesion process between a resin and a copper foil, or a solder process. Due to this heat, copper may diffuse to the resin side and reduce the adhesion between copper and resin, but by providing the metal treatment layer, copper diffusion is prevented and high adhesion to the resin substrate is achieved. Sex can be maintained more stably. Moreover, the metal which comprises a metal processing layer functions also as a rust prevention metal which prevents the rust of copper.
From the viewpoint of further improving the etching property of the copper foil, it is also important to control the amount of nickel as a rust preventive metal on the surface on which the roughened particles are formed before the silane coupling agent treatment. That is, when there is a large amount of nickel adhered, copper rust is less likely to occur, and the adhesiveness to the resin at high temperatures tends to improve, but nickel tends to remain after etching, and sufficient insulation reliability is difficult to obtain. When the surface-treated copper foil of the present invention has a metal treatment layer, the amount of nickel element on the roughened surface is 0.1 mg / dm ² or more and 0.3 mg / dm from the viewpoint of achieving both adhesion and etching at high temperatures. It is preferable to be less than ² .

[Manufacture of surface-treated copper foil for printed wiring boards]
<Copper foil>
As copper foil used for manufacture of the surface-treated copper foil of this invention, it can select according to uses and other objectives, such as rolled copper foil and electrolytic copper foil. There is no restriction | limiting in particular in the foil thickness of the copper foil used for the surface treatment copper foil of this invention, What is necessary is just to select suitably according to the objective. The foil thickness is usually 4 to 120 μm, preferably 5 to 50 μm, and more preferably 6 to 18 μm.

<Roughening plating treatment>
In the production of the surface-treated copper foil of the present invention, the roughened surface can be formed by applying specific roughened plating conditions. That is, according to the present invention, it is possible for the present inventors to form the roughened surface by performing electroplating treatment within a specific range of molybdenum concentration and under specific conditions described later. It is an invention based on finding out.

(Roughening plating conditions)
In order to make it possible to form the roughened surface, it is necessary to control the molybdenum concentration to 50 mg / L or more and 600 mg / L or less in the roughing plating process (electroplating process). If the molybdenum concentration is less than 50 mg / L, problems such as powder falling are likely to occur, and if it exceeds 600 mg / L, the surface after treatment with the silane coupling agent (that is, the roughened surface) BET while satisfying other characteristics. It becomes difficult to increase the surface area ratio to 1.2 or more.

  In order to make it possible to form the roughened surface, it is necessary that the flow rate between the electrodes be 0.15 m / second or more and 0.4 m / second or less in the roughing plating treatment. When the inter-electrode flow rate is less than 0.15 m / sec, the desorption of hydrogen gas generated on the copper foil does not proceed and the effect of molybdenum is difficult to obtain, and problems such as powder falling are likely to occur. Further, when the inter-electrode flow rate exceeds 0.4 m / sec, the supply of copper ions to fine recesses proceeds excessively, and the recesses are filled with plating, and the BET surface area ratio of the surface after the silane coupling agent treatment is 1.2. It becomes difficult to raise more.

In order to enable the formation of the roughened surface, the value obtained by multiplying the current density by the treatment time in the roughing plating process is 20 (A / dm ² ) · second or more and 250 (A / dm ² ) · second. It is necessary to: When this value is less than 20 (A / dm ² ) · sec, it becomes difficult to make the average height of the roughened particles on the roughened surface after the silane coupling agent treatment 0.05 μm or more. It becomes difficult to ensure sufficient adhesion with the resin to be laminated. On the other hand, if it exceeds 250 (A / dm ² ) · sec, it becomes difficult to make the average height of the formed coarse particles less than 0.5 μm, so that transmission loss tends to deteriorate. A value obtained by multiplying the current density by the treatment time is preferably 20 (A / dm ² ) · second or more and less than 160 (A / dm ² ) · second.

In order to make it possible to form the roughened surface, the value obtained by multiplying the current density multiplied by the processing time by the Mo concentration in the roughing plating process is 1.0 {(A / dm ² ) · sec. } / (Mg / L) to 3.0 {(A / dm ² ) · second} / (mg / L) or less. When this value is less than 1.0 {(A / dm ² ) · sec} / (mg / L), it is difficult to obtain a sufficient BET surface area ratio while satisfying other characteristics. If this value exceeds 3.0 {(A / dm ² ) · second} / (mg / L), it tends to be difficult to make Cms less than 8.0 . The value obtained by multiplying the above current density by the treatment time divided by the Mo concentration is 1.2 {(A / dm ² ) · sec} / (mg / L) or more and 2.4 {(A / dm ² ). -It is preferable to be less than second} / (mg / L).

The preferable roughening plating process conditions for enabling the formation of the roughened surface are shown below.
-Roughening plating conditions-
Cu: 10 to 30 g / L
H ₂ SO _4: 100~200g / L
Bath temperature: 20-30 ° C
Mo concentration: 50-600 mg / L
Inter-electrode flow velocity: 0.15-0.4 m / sec Current density: 15-70 A / dm ²
Treatment time: 0.1 to 10 seconds Current density × treatment time: 20 to 250 (A / dm ² ) · second Current density × treatment time ÷ Mo concentration: 1.0 to 3.0 {(A / dm ² ) · Second} / (mg / L)

  In addition, the addition of molybdenum to the plating solution is a form in which molybdenum dissolves as ions, and it must change the pH of the copper sulfate plating solution or contain metal impurities that are incorporated into the copper plating film. There is no particular limitation. For example, an aqueous solution of molybdate (for example, sodium molybdate or potassium molybdate) can be added to the copper sulfate plating solution.

<Metal treatment layer>
When the surface-treated copper foil of this invention has a metal treatment layer, there is no restriction | limiting in particular in the formation method of a metal treatment layer, It can form by a conventional method. For example, taking a case where a metal treatment layer having nickel, zinc and chromium is formed as an example, a metal treatment layer is formed by applying nickel plating, zinc plating and chromium plating in this order, for example, under the following conditions. Can do.

(Ni plating)
Ni: 10 to 100 g / L
H ₃ BO ₃ : 1 to 50 g / L
PO ₂ : 0 to 10 g / L
Bath temperature: 10-70 ° C
Current density: 1 to 50 A / dm ²
Treatment time: 1 second to 2 minutes pH: 2.0 to 4.0
(Zn plating)
Zn: 1 to 30 g / L
NaOH: 10 to 300 g / L
Bath temperature: 5-60 ° C
Current density: 0.1 to 10 A / dm ²
Processing time: 1 second to 2 minutes (Cr plating)
Cr: 0.5 to 40 g / L
Bath temperature: 20-70 ° C
Current density: 0.1 to 10 A / dm ²
Treatment time: 1 second to 2 minutes pH: 3.0 or less

In the surface-treated copper foil of the present invention, the amount of Si element existing on the roughened surface (that is, the amount of Si element contained in the silane coupling agent layer) is 0.5 μg / dm ² or more and less than 15 μg / dm ^2. It is preferable. By setting the amount of Si element to 0.5 μg / dm ² or more and less than 15 μg / dm ² , it is possible to effectively improve the adhesion to the resin while suppressing the amount of the silane coupling agent used. The amount of Si element contained in the silane coupling agent layer is more preferably 3 μg / dm ² or more and less than 15 μg / dm ² , and further preferably 5 μg / dm ² or more and less than 15 μg / dm ² .
The said silane coupling agent is suitably selected according to the molecular structure (kind of functional group etc.) of the resin which comprises the resin layer laminated | stacked with the surface modification copper foil of this invention. Among these, the silane coupling agent is at least one selected from an epoxy group, an amino group, a vinyl group, a (meth) acryloyl group, a styryl group, a ureido group, an isocyanurate group, a mercapto group, a sulfide group, and an isocyanate group. It preferably has a functional group. “(Meth) acryloyl group” means “acryloyl group and / or methacryloyl group”.

The treatment with the silane coupling agent on the surface of the copper foil on which the roughened particles are formed can be performed by a conventional method. For example, a silane coupling agent solution (coating solution) is prepared, and this coating solution is applied to the surface of the copper foil on which the roughened particles are formed and dried, so that the silane cup is formed on the surface of the copper foil on which the roughened particles are formed. A ring agent can be adsorbed or bound. As the coating solution, for example, a solution containing a silane coupling agent at a concentration of 0.05 wt% to 1 wt% using pure water can be used.
There is no particular limitation on the coating method of the coating solution. For example, in a state where the copper foil is slanted, the coating solution is uniformly flowed on the surface on which the roughened particles are formed, and after being drained using a roll, it is dried by heating. Alternatively, it can be applied by spraying a coating solution on a copper foil stretched with the surface on which the roughened particles are formed facing down between the rolls, and then drying by heating after draining with a roll. There is no restriction | limiting in particular in application | coating temperature, Usually, it implements at 10-40 degreeC.

[Copper-clad laminate for printed wiring boards]
The copper-clad laminate for printed wiring boards of the present invention (hereinafter referred to as “the copper-clad laminate of the present invention”) has a resin layer (resin substrate) on the roughened surface of the surface-treated copper foil of the present invention. It has a laminated structure. There is no restriction | limiting in particular in the said resin layer, The resin layer normally used for the copper clad laminated board for producing a printed wiring board is employable. For example, a halogen-free low dielectric base material used for a rigid substrate or a low dielectric polyimide widely used for a flexible substrate can be used.
There is no restriction | limiting in particular in the lamination | stacking method of surface-treated copper foil and a resin base material, For example, copper foil and a resin base material can be adhere | attached by the hot-press molding method etc. which used the hot press processing machine. It is preferable that the press temperature in the said hot-press molding method shall be about 150-400 degreeC. The press pressure is preferably about 1 to 50 MPa.
The thickness of the copper clad laminate is preferably 10 to 1000 μm.

[Printed wiring board]
The printed wiring board of the present invention is produced using the copper clad laminate of the present invention. That is, the copper-clad laminate of the present invention can be processed by etching or the like to form a conductor circuit pattern, and other components can be formed or mounted by a conventional method as required.

  Below, based on an Example, this invention is demonstrated further in detail. The following is an example of the present invention, and various forms can be employed in implementing the present invention without departing from the spirit of the present invention.

[Manufacture of copper foil]
Electrolytic copper foil or rolled copper foil was used as the copper foil serving as the base material for the roughening treatment.
In Examples 1, 2, 4, 5, 7 and 8, Comparative Examples 1 to 4 and 7 and Reference Example 1, an electrolytic copper foil having a thickness of 12 μm produced under the following conditions was used.
<Production conditions for electrolytic copper foil>
CuSO ₄ : 280 g / L
H ₂ SO ₄ : 70 g / L
Chlorine concentration: 25 mg / L
Bath temperature: 55 ° C
Current density: 45 A / dm ²
(Additive)
・ 3-mercapto 1-propanesulfonic acid sodium salt: 2 mg / L
Hydroxyethyl cellulose: 10 mg / L
・ Low molecular weight glue (molecular weight 3000): 50 mg / L

In Examples 3 and 6 and Comparative Examples 5 and 6, a commercially available 12 μm tough pitch copper rolled foil (manufactured by UACJ Co., Ltd.) subjected to degreasing treatment under the following conditions was used.
<Degreasing conditions>
Degreasing solution: Aqueous solution of cleaner 160S (Meltex Co., Ltd.) Concentration: 60 g / L aqueous solution Bath temperature: 60 ° C
Current density: 3 A / dm ²
Energizing time: 10 seconds

[Formation of roughened surface]
A roughened plated surface was formed on one side of the copper foil by electroplating. The roughening plating treatment surface uses the following rough plating solution basic bath composition, the molybdenum concentration is as shown in Table 1 below, and the interelectrode flow velocity, current density, and treatment time are as shown in Table 1 below. Formed as. The molybdenum concentration was adjusted by adding an aqueous solution of sodium molybdate dissolved in pure water to the basic bath.
<Roughening plating solution basic bath composition>
Cu: 25 g / L
H ₂ SO ₄ : 180 g / L
Bath temperature: 25 ° C

<Formation of metal treatment layer>
Subsequently, the surface subjected to the roughening plating treatment was further subjected to metal plating in the order of Ni, Zn, and Cr under the following conditions to form a metal treatment layer. In Reference Example 1, no metal treatment layer was formed.
<Ni plating>
Ni: 40 g / L
H ₃ BO ₃ : 5 g / L
Bath temperature: 20 ° C
pH: 3.6
Current density: 0.2 A / dm ²
Energizing time: 10 seconds <Zn plating>
Zn: 2.5 g / L
NaOH: 40 g / L
Bath temperature: 20 ° C
Current density: 0.3 A / dm ²
Energizing time: 5 seconds <Cr plating>
Cr: 5 g / L
Bath temperature: 30 ° C
pH: 2.2
Current density: 5 A / dm ²
Energizing time: 5 seconds

<Application of silane coupling agent (formation of roughened surface)>
A solution (30 ° C.) of a commercially available silane coupling agent shown in Table 2 was applied to the entire surface of the metal treatment layer, and excess liquid was removed with a squeegee, followed by drying at 120 ° C. in the atmosphere for 30 seconds. The preparation method of each silane coupling agent solution is as follows.

3-Glycidoxypropylmethyldimethoxysilane (KBM-402 manufactured by Shin-Etsu Chemical Co., Ltd.): A 0.3 wt% solution is prepared with pure water.
3-aminopropyltrimethoxysilane (KBM-903, manufactured by Shin-Etsu Chemical Co., Ltd.): A 0.25 wt% solution was prepared with pure water.
Vinyltrimethoxysilane (KBE-1003 manufactured by Shin-Etsu Chemical Co., Ltd.): A 0.2 wt% solution was prepared with a solution adjusted to pH 3 by adding sulfuric acid to pure water.
3-Methacryloxypropylmethyldimethoxysilane (KBM-502 manufactured by Shin-Etsu Chemical Co., Ltd.): A 0.25 wt% solution was prepared with a solution adjusted to pH 3 by adding sulfuric acid to pure water.
3-isocyanatopropyltriethoxysilane (KBE-9007 manufactured by Shin-Etsu Chemical Co., Ltd.): A 0.2 wt% solution was prepared with a solution adjusted to pH 3 by adding sulfuric acid to pure water.
3-ureidopropyltriethoxysilane (KBE-585, manufactured by Shin-Etsu Chemical Co., Ltd.): A 0.3 wt% solution is prepared with a solution in which ethanol and pure water are mixed at a ratio of 1: 1.

[Measurement of average height of roughened particles]
The average height of the roughened particles on the roughened surface was obtained by SEM observation of a cross section parallel to the thickness direction of the copper foil obtained by ion milling. Details will be described below.
FIG. 1 is a SEM image of a cross section parallel to the thickness direction of the roughened surface (surface after silane coupling agent treatment) of the surface-treated copper foil produced in Comparative Example 6. Similarly, in the cross section of each copper foil, the top and bottom of the roughened particles can be confirmed within the field of view, and SEM observation is performed for five different fields of view at a magnification that includes about 10 roughened particles. did. For each of the five fields of view of one copper foil, the height of the roughened particles having the highest height is measured, and the average of the five measured values (maximum values) obtained is the roughened surface of the copper foil. The average height of roughened particles in
A method for measuring the height of the roughened particles will be described in detail with reference to the drawings. As shown in FIG. 1, the rough particle to be measured has the longest shortest distance from the straight line connecting the left and right bottoms (the straight line connecting points a and b) of the rough particle to be measured. The shortest distance between the top (point c) and the straight line connecting points a and b was defined as the height H of the roughened particles.
2 is an SEM image of a cross section parallel to the thickness direction of the roughened surface (surface after silane coupling treatment) of the surface-treated copper foil produced in Example 2. FIG. When the roughened particles are branched and formed in this way, the whole including the branched structure is regarded as one roughened particle. That is, the top of the roughened particles (point f) having the longest shortest distance from the straight line connecting the left and right bottoms of the roughened particles formed in a dendritic shape (straight line connecting points d and e) The shortest distance between the point d and the straight line connecting the points e was defined as the height H of the roughened particles.
The results are shown in Table 3 below.

[Measurement of BET surface area ratio A]
The BET surface area ratio A is calculated by dividing the surface area of the roughened surface (BET measurement surface area) measured by the BET method by the sample cut-out area that is the planar view area.
The BET measurement surface area was measured by a krypton gas adsorption BET multipoint method using a gas adsorption pore distribution measuring device ASAP2020 manufactured by Micromeritics. Prior to measurement, vacuum drying was performed at 150 ° C. for 6 hours as a pretreatment.
A sample (copper foil) used for the measurement was cut into 3 dm ² to be approximately 3 g, cut into 5 mm squares, and then introduced into the measuring apparatus.
In the surface area measurement by the BET method, since the surface area of the entire surface of the sample introduced into the apparatus is measured, it is not possible to measure the surface area of only the roughened surface in the surface-treated copper foil subjected to the roughening treatment on one side. Therefore, the BET surface area ratio A was actually calculated by the following formula.

<BET surface area ratio A>
The surface area ratio of the surface not subjected to the roughening treatment (surface opposite to the roughening treatment surface) was regarded as 1, that is, the same as the sample cut-out area, and the BET surface area ratio A was calculated by the following formula.
(BET surface area ratio A) = [(BET measurement surface area) − (sample cutout area)] / (sample cutout area)

In addition, in the surface area measurement of the BET method, a surface other than the roughened surface and the surface that has not been roughened (
The surface area of the side surface) is also measured, but even if it is 120 μm, which is the thickest foil thickness assumed by the present invention, the ratio is less than 5% of the total planar view area, so it can be virtually ignored.

  When the surface is not roughened as in Reference Example 1, the BET measurement surface area may be smaller than the cut-out area due to the measurement principle of the BET method (that is, the BET surface area ratio A is less than 1). Sometimes). On the other hand, when a surface having fine irregularities is formed by the roughening treatment, it is possible to detect fine irregularities and the like with high sensitivity by applying the BET method. As a result, the BET surface area ratio A is 1 It will be over.

[Measurement of laser surface area ratio B]
The laser surface area ratio B was calculated based on the measured surface area using a laser microscope VK8500 (manufactured by Keyence Corporation). More particularly, the roughening treated surface of the sample (copper foil), and observed at a magnification 1000 times, to measure the three-dimensional surface area of the plan view area 6550Myuemu ² portions, dividing the three-dimensional surface area 6550Myuemu ² Thus, the laser surface area ratio B was determined. The measurement pitch was 0.01 μm. The results are shown in Table 3.

[Calculation of fine surface coefficient Cms]
The fine surface coefficient Cms was calculated based on the following formula using the BET surface area ratio A and the laser surface area ratio B. The results are shown in Table 3 below.

Fine surface coefficient Cms = BET surface area ratio A / laser surface area ratio B

[Measurement of Si]
The amount of Si element (μg / dm ² ) on the roughened surface (that is, the amount of Si element contained in the silane coupling agent layer) is obtained after masking the surface of the sample that has not been subjected to roughening plating with a paint. After cutting into a 10 cm square and dissolving only the surface part with a mixed acid (nitric acid 2: hydrochloric acid 1: pure water 5 (volume ratio)) heated to 80 ° C., the Si mass in the resulting solution was determined by Hitachi High-Tech Science Corporation. It was determined by quantitative analysis by atomic absorption spectrometry using an atomic absorption spectrophotometer (model: Z-2300). The results are shown in Table 3 below as the amount of Si element.

[Measurement of brightness index L ^* ]
Lightness index ^{L *} is ^{L *} in JIS-Z8729 color system as defined in ^L * ^a * ^{b *.} For measurement of the lightness index L ^*, an ultraviolet-visible spectrophotometer V-660 (integrating sphere unit) manufactured by JASCO Corporation was used. The total light spectral reflectance of the roughened surface was measured between wavelengths 870 and 200 nm. From the obtained spectrum, the lightness index L ^* value was calculated by the software attached to the measuring instrument and is shown in Table 3.

[Evaluation of high frequency characteristics]
As an evaluation of high frequency characteristics, transmission loss in the high frequency band was measured. The roughened surface (surface treated with a silane coupling agent) of the surface-treated copper foil having a roughened surface produced in each of the above examples and comparative examples is a polyphenylene ether-based low dielectric constant manufactured by Panasonic Corporation. A copper-clad laminate was prepared by pressing the resin base material MEGTRON 6 (thickness 50 to 100 μm) for 2 hours under conditions of a surface pressure of 3 MPa and 200 ° C. Circuit processing was performed on the obtained laminated plate, and MEGRON 6 was further laminated thereon to finally form a three-layer copper-clad laminate. The transmission line was a microstrip line having a width of 100 μm and a length of 40 mm. A high frequency signal up to 100 GHz was transmitted to this transmission line using a network analyzer, and the transmission loss was measured. The characteristic impedance was 50Ω.
The measured value of transmission loss means that the smaller the absolute value, the smaller the transmission loss and the better the high frequency characteristics. Table 4 lists the evaluation results of transmission loss at 20 GHz and 70 GHz. The evaluation criteria are as follows.
<20 GHz transmission loss evaluation criteria>
◎: Transmission loss is −6.2 dB or more ○: Transmission loss is less than −6.2 dB to −6.5 dB or more ×: Transmission loss is less than −6.5 dB <70 GHz transmission loss evaluation criteria>
A: Transmission loss is −20.6 dB or more ○: Transmission loss is less than −20.6 dB to −24.0 dB or more ×: Less than −24.0 dB

Furthermore, based on the evaluation result of the transmission loss, high frequency characteristics were comprehensively evaluated based on the following evaluation criteria. The results are shown in Table 4 below.
<High-frequency characteristics comprehensive evaluation criteria>
A (excellent): The evaluation results of the transmission loss of 20 GHz and the transmission loss of 70 GHz are both A.
○ (good): The evaluation result of the transmission loss at 20 GHz is “◎”, and the evaluation result of the transmission loss at 70 GHz is “◯”.
Δ (pass): The evaluation result of the transmission loss at 70 GHz is “x”, but the transmission loss at 20 GHz is “◎” or “◯”.
X (failure): The evaluation results of the transmission loss of 20 GHz and the transmission loss of 70 GHz are both x.

[Evaluation of visibility]
As an evaluation of visibility, the haze (haze value) was measured. Copper-clad laminates laminated on both sides of PIXEO (FRS-522, thickness 12.5 μm), which is a polyimide for laminating manufactured by Kaneka Co., Ltd., with the roughened surface of the samples produced in Examples and Comparative Examples as the resin-bonded surface. Was made. About those copper clad laminated boards, the copper foil bonded on both surfaces was removed by etching with an aqueous copper chloride solution to prepare a sample film for haze measurement.
About the produced sample film, the haze was measured based on the method as described in JISK7136: 2000 using the JASCO-made ultraviolet visible spectrophotometer V-660 (integral sphere unit). (Td / Tt) × 100 (%) was calculated as a haze value (Tt: total light transmittance, Td: diffuse transmittance).
The haze value represents the haze of the sample film. The smaller the value, the lower the haze and the better the visibility. Such visibility was evaluated based on the following evaluation criteria. The results are shown in Table 4 below.
<Evaluation criteria for visibility>
◎: Haze value is less than 30% ○: Haze value is 30% or more and less than 60% Δ: Haze value is 60% or more and less than 80% ×: Haze value is 80% or more

  If the visibility is ◎, ○ or Δ, it can be said that the visibility is acceptable in practice.

[Evaluation of adhesion-1]
Adhesion was evaluated by a peel test. A copper-clad laminate was produced in the same manner as the copper-clad laminate produced in [Evaluation of high-frequency characteristics], and the copper foil part of the obtained copper-clad laminate was masked with a 10 mm width tape. The copper-clad laminate was etched with copper chloride, and then the tape was removed to prepare a circuit wiring board having a width of 10 mm. Using a Tensilon tester manufactured by Toyo Seiki Seisakusho Co., Ltd., peel strength when peeling a 10 mm wide circuit wiring portion (copper foil portion) of this circuit wiring board from a resin base material at a speed of 50 mm / min in a 90 degree direction. It was measured. Using the obtained measured value as an index, the adhesion was evaluated based on the following evaluation criteria. Note that the MEGRON 6 resin has a greater contribution to the anchoring effect on adhesion than the PIXEO resin. The results are shown in Table 4 below.
<Adhesion evaluation criteria>
○: Peel strength is 0.6 kN / m or more Δ: Peel strength is 0.5 kN / m or more and less than 0.6 kN / m ×: Peel strength is less than 0.5 kN / m

[Evaluation of adhesion-2]
A copper-clad laminate was produced in the same manner as the copper-clad laminate produced in the above [Evaluation of visibility], and the copper foil part of the obtained copper-clad laminate was masked with a 10 mm width tape. The copper-clad laminate was etched with copper chloride, and then the tape was removed to prepare a circuit wiring board having a width of 10 mm. Using a Tensilon tester manufactured by Toyo Seiki Seisakusho Co., Ltd., peel strength when peeling a 10 mm wide circuit wiring portion (copper foil portion) of this circuit wiring board from a resin base material at a speed of 50 mm / min in a 90 degree direction. It was measured. Using the obtained measured value as an index, the adhesion was evaluated based on the following evaluation criteria. The results are shown in Table 4 below.
<Adhesion evaluation criteria>
○: Peel strength is 1 kN / m or more ×: Peel strength is less than 1 kN / m

Furthermore, based on the said evaluation result of adhesiveness, adhesiveness was comprehensively evaluated based on the following evaluation criteria. The results are shown in Table 4 below.
<Adhesion comprehensive evaluation criteria>
A (excellent): Both evaluation results of [Adhesion Evaluation-1] and [Adhesion Evaluation-2] are ◯.
○ (Pass): The evaluation result of [Adhesion Evaluation-1] is Δ, and the evaluation result of [Adhesion Evaluation-2] is ○.
X (failure): The evaluation result of at least one of [Adhesion evaluation-1] and [Adhesion evaluation-2] is x.

[Comprehensive evaluation]
All of the above high-frequency characteristics, visibility, and adhesiveness were synthesized and comprehensively evaluated based on the following evaluation criteria.
<Evaluation criteria for comprehensive evaluation>
A (excellent): The results of overall evaluation of high-frequency characteristics, evaluation of visibility, and comprehensive evaluation of adhesion are all “密 着”.
B: (Accepted): The above A is not satisfied, but there is no x in the results of the comprehensive evaluation of the high frequency characteristics, the evaluation of the visibility, and the comprehensive evaluation of the adhesion.
C (failure): At least one evaluation result of comprehensive evaluation of high-frequency characteristics, evaluation of visibility, and comprehensive evaluation of adhesion is x.

Consider the results shown in the above tables.
Comparative Example 1 is an example in which the average height of the roughened particles present on the roughened surface of the surface-treated copper foil is smaller than that defined in the present invention. When the copper clad laminated board was produced using the surface-treated copper foil of the comparative example 1, it was inferior to the adhesiveness of copper foil and a resin base material.
Comparative Examples 2, 3 and 7 are examples in which both the BET surface area ratio and Cms of the roughened surface of the surface-treated copper foil are smaller than those defined in the present invention. When the copper clad laminated board was produced using the surface-treated copper foils of Comparative Examples 2, 3 and 7, the adhesion between the copper foil and the resin base material was inferior.
Comparative Examples 4 and 5 are examples in which the average height of the roughened particles existing on the roughened surface of the surface-treated copper foil is larger than that defined in the present invention. When copper-clad laminates were produced using the surface-treated copper foils of Comparative Examples 4 and 5 and a conductor circuit was formed, the results were greatly inferior in both high-frequency characteristics and visibility.
Comparative Example 6 is an example in which Cms is smaller than that defined in the present invention. When a copper-clad laminate was produced using the surface-treated copper foil of Comparative Example 6, MEGRON 6 resin, which greatly contributes to the anchor effect on adhesion, resulted in poor adhesion.
Reference Example 1 is an example in which the copper foil is not subjected to a roughening treatment, and further, neither a metal treatment layer is formed nor a silane coupling agent treatment is performed. When the copper clad laminated board was produced using the copper foil of the reference example 1, it became a result inferior to the adhesiveness of copper foil and a resin base material greatly.

  In contrast, the average height of the roughened particles formed on the roughened surface of the surface-treated copper foil is within the range defined by the present invention, and the BET surface area ratio and Cms of the roughened surface are also present. The surface-treated copper foils of Examples 1 to 8 that satisfy the specifications in the invention were excellent in adhesion between the copper foil and the resin base material when a copper-clad laminate was produced using this. Moreover, the conductor circuit formed from the copper clad laminated board using the surface-treated copper foil of Examples 1-8 can suppress transmission loss effectively, even if it transmits a high frequency signal, Furthermore, the surface treatment of Examples 1-8 The resin base material on which the copper foil was laminated and adhered showed good visibility when the copper foil was removed by etching thereafter.

Claims (8)

A surface-treated copper foil for a printed wiring board having a silane coupling agent layer on the surface on which roughened particles are formed by roughening plating ,
On the surface of the silane coupling agent layer, the average height of the roughened particles is 0.05 μm or more and less than 0.5 μm,
A surface-treated copper foil for a printed wiring board, wherein a BET surface area ratio on the surface of the silane coupling agent layer is 1.2 or more and a fine surface coefficient Cms is 2.0 or more and less than 8.0.   The surface-treated copper foil for printed wiring boards of Claim 1 whose average height of a roughening particle is 0.05 micrometer or more and less than 0.3 micrometer on the said silane coupling agent layer surface. The silane coupling agent layer ^{surface, L * a * b * L} * in the color system is less than 40 or more 60, claim 1 or 2 for a printed circuit board surface-treated copper foil according to.   The surface on which the roughened particles are formed has a metal treatment layer having at least one metal selected from chromium, iron, cobalt, nickel, copper, zinc, molybdenum, and tin, or chromium, iron The surface for printed wiring boards of any one of Claims 1-3 which has a metal treatment layer which has an alloy which consists of 2 or more types of metals chosen from cobalt, nickel, copper, zinc, molybdenum, and tin Treated copper foil. The surface-treated copper foil for printed wiring boards according to any one of claims 1 to 4, wherein an amount of Si element contained in the silane coupling agent layer is 0.5 µg / dm ² or more and less than 15 µg / dm ^2. .   The silane coupling agent is at least one functional group selected from an epoxy group, an amino group, a vinyl group, a (meth) acryloyl group, a styryl group, a ureido group, an isocyanurate group, a mercapto group, a sulfide group, and an isocyanate group. The surface-treated copper foil for printed wiring boards of any one of Claims 1-5 which has these.   The copper clad laminated board for printed wiring boards by which the resin layer is laminated | stacked on the said silane coupling agent layer surface of the surface treatment copper foil for printed wiring boards of any one of Claims 1-6. The printed wiring board using the copper clad laminated board for printed wiring boards of Claim 7.