KR20180037133A - A surface-treated copper foil for a printed wiring board, a copper clad laminate for a printed wiring board and a printed wiring board - Google Patents

Abstract

A surface-treated copper foil for a printed wiring board having a silane coupling agent layer on a surface on which roughening particles are formed,
Wherein the average height of the roughening particles in the surface of the silane coupling agent layer is 0.05 탆 or more and less than 0.5 탆,
Wherein the BET surface area ratio of the surface of the silane coupling agent layer is 1.2 or more and the fine surface coefficient Cms is 2.0 or more and less than 8.0.

Description

A surface-treated copper foil for a printed wiring board, a copper clad laminate for a printed wiring board and a printed wiring board

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

2. Description of the Related Art In recent years, with the advancement of high performance and high functionality of computers and information communication devices and progress of networking, it has become necessary to transmit large amounts of information at higher speeds. Therefore, a signal to be transmitted tends to be increased in frequency, and a printed wiring board in which the transmission loss of a high-frequency signal is suppressed is required. In the production of a printed wiring board, a copper-clad laminated board is usually produced by laminating a copper foil and an insulating base material (resin base) and heating and pressing them, and a conductor circuit is formed by using this copper clad laminate. Three factors of the conductor loss, the dielectric loss and the radiation loss are related to the transmission loss when the high frequency signal is transmitted to the conductor circuit (high frequency transmission).

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 by using a copper clad laminate, a skin effect phenomenon occurs. That is, when the alternating current is passed through the conductor circuit, the magnetic flux changes and a back electromotive force is generated in the center of the conductor circuit. As a result, the current hardly flows through the conductor center. Conversely, the current density of the conductor surface portion (skin portion) increases. This skin effect phenomenon reduces the effective cross-sectional area of the conductor, so that so-called skin resistance occurs. The thickness (skin depth) of the epidermal section through which current flows is inversely proportional to the square root of the frequency.

Recently, high-frequency devices exceeding 20 GHz have been developed. When a high-frequency signal of a GHz frequency band is transmitted to the conductor circuit, the skin depth becomes about 2 μm or less, and the current does not flow only on the very surface layer of the conductor. Therefore, when the surface roughness of the copper foil is large in the copper-clad laminate used for the high-frequency device, the transmission path of the conductor formed by the copper foil becomes long and the transmission loss increases. Therefore, it is preferable that the surface roughness of the copper foil of the copper clad laminate used in high-frequency equipment is reduced.

On the other hand, a copper foil used for a printed wiring board generally has a roughened layer (a layer in which roughened particles are formed) is formed on its surface by a technique such as electroplating or etching, and a physical effect ) To improve adhesion to the resin substrate. However, if the coarsened particles formed on the surface of the copper foil are increased in order to effectively increase the adhesive force with the resin base material, the transmission loss increases as described above.

The dielectric loss is due to the dielectric constant and dielectric tangent of the resin substrate. When a pulse signal is passed through the conductor circuit, a change occurs in the electric field around the conductor circuit. When the period (frequency) of the change of the electric field becomes closer to the relaxation time of the polarization of the resin base material (the movement time of the charge object causing the polarization) (that is, when the frequency becomes high), a delay occurs in the electric field change. In such a state, molecular friction occurs in the resin, heat is generated, and transmission loss is caused. In order to suppress this dielectric loss, a resin having a small amount of high polarity substituent or a resin having no high polarity substituent is employed as the resin base material of the copper clad laminate, and polarization of the resin base material along with the change in electric field is made difficult There is a need.

On the other hand, in addition to the formation of the above-mentioned roughening treatment layer, the copper foil used in the printed wiring board may be treated with a silane coupling agent to improve the chemical bonding strength with the resin base material. In order to improve the chemical adhesion between the silane coupling agent and the resin substrate, the resin substrate needs to have a substituent having a certain polarity to some extent. However, in order to suppress the dielectric loss, the resin substrate has a low dielectric constant When the base material is used, the chemical bonding strength is lowered, and sufficient adhesion between the copper foil and the resin base material is difficult to be secured.

As described above, in the copper clad laminate, the transmission loss is suppressed and the adhesiveness (adhesion) between the copper foil and the resin substrate is improved (durability is improved).

In recent years, high-frequency compatible printed wiring boards have been developed in fields where reliability is more demanded. For example, in the use as a printed wiring board for mobile communication such as a vehicle application, a high reliability that can withstand use under harsh environments is required. In the copper clad laminate corresponding to this demand, it is necessary to highly increase the adhesion between the copper foil and the resin base material.

Technological development is proceeding to satisfy the above requirements. For example, Patent Document 1 discloses a method in which coarse particles are adhered to a copper foil to form a roughened surface having a surface roughness Rz of 1.5 to 4.0 μm and a lightness value (brightness value) of 30 or less, A surface treated copper foil which is evenly distributed and has protrusions formed from the above-mentioned roughening particles has a specific height and width. By using the surface treated copper foil, the adhesiveness to a resin substrate for a high frequency circuit board including liquid crystal polymer It can be increased.

Flexible printed wiring boards (hereinafter referred to as FPCs) are employed in small electronic devices such as smart phones and tablet PCs because of their ease of wiring and light weight. In recent years, as these small electronic devices have become more sophisticated, signal transmission speeds have increased, and impedance matching (matching of output resistance and input resistance) of the FPC has become important. A resin substrate (typically, polyimide) serving as a base of the FPC is layered (thickened) in order to realize impedance matching for increasing the signal transmission speed.

The FPC is subjected to predetermined processing such as bonding to a liquid crystal substrate or mounting of an IC chip. The alignment at the time of machining is performed with the positioning pattern (which is recognized as an eye) which is transmitted through the resin base material of the portion from which the copper foil is removed by etching as an index. For this reason, the permeability (visibility) of the resin substrate becomes important in the alignment. The transparency of this resin base material is generally evaluated and controlled by using the total light transmittance and haze (haze value) in the visible light region. In recent years, diversification of the layering and alignment process of the resin substrate has progressed, and the level of permeability required for the resin substrate after etching has increased. The permeability of the resin substrate after etching greatly affects the surface shape of the copper foil applied to the resin base material in addition to the characteristics of the resin itself.

A resin substrate having flexibility such as polyimide or liquid crystal polymer is brought into contact with the copper foil under high temperature and high pressure conditions. At this time, since the resin enters the roots of the roughening particles formed on the roughened surface of the copper foil, the larger the roughening particles are, the deeper the projections and projections transferred to the resin become, and as a result, It tends to be scattered, and the permeability tends to deteriorate.

Patent Document 2 discloses an FPC in which an adhesive layer bonded to an insulating layer is provided with an anti-rust treatment layer made of a nickel-zinc alloy, and the surface roughness (Rz) of the adhesive surface is 0.05 (COF) type having an electroconductive copper foil having a specular gloss of at least 250 and an incident angle of 60 DEG or more and having an excellent light transmittance, Is also good.

In Patent Document 3, roughened particles are formed by roughening treatment, the roughened surface has an average roughness Rz of 0.5 to 1.3 μm and a gloss of 4.8 to 68, and the surface area A of the roughened particles and the roughening particles Treated copper foil having a ratio A / B to an area B obtained when viewed from the front side from the surface side of the copper foil is 2.00 to 2.45, and the copper-clad laminate formed by laminating the copper foil with the surface- It is described that the resin transparency is good and the adhesion between the copper foil and the resin is good.

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

The surface-treated copper foil described in Patent Document 1 is excellent in adhesion to a high frequency compatible resin base material. However, the copper-clad laminate using the surface-treated copper foil has a high transmission loss in the high frequency band of GHz band, It did not come to a sufficient degree to satisfy the requirement of.

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

In the surface-treated copper foil described in Patent Document 3, when a low-dielectric base material is used as the resin base material, sufficient adhesion with the resin base material is not obtained.

Disclosed is a surface-treated copper foil for printed wiring boards, which is capable of highly suppressing transmission loss even when a high-frequency signal of GHz band is transmitted, achieving a printed wiring board having high adhesion with resin base material and excellent durability, . It is another object of the present invention to provide a copper clad laminate for a printed wiring board and a printed wiring board (circuit board) using the surface-treated copper foil for a printed wiring board.

The above object of the present invention is solved by the following means.

[One]

A surface-treated copper foil for a printed wiring board having a silane coupling agent layer on a surface on which roughening particles are formed,

Wherein the average height of the roughening particles in the surface of the silane coupling agent layer is 0.05 탆 or more and less than 0.5 탆,

Wherein the BET surface area ratio of the surface of the silane coupling agent layer is 1.2 or more and the fine surface coefficient Cms is 2.0 or more and less than 8.0.

[2]

The surface-treated copper foil for a printed wiring board according to [1], wherein the average height of the roughening particles on the surface of the silane coupling agent layer is 0.05 m or more and less than 0.3 m.

[3]

Of the silane coupling agent layer on the surface, L ^* a ^* b ^* color system of L ^* a table 40 or 60 is less than [1] or [2] The surface-treated copper foil for printed wiring board according to according to.

[4]

Wherein the surface on which the roughening particles are formed has a metal treatment layer having at least one metal selected from the group consisting of chromium, iron, cobalt, nickel, copper, zinc, molybdenum and tin, The surface-treated copper foil for a printed wiring board according to any one of [1] to [3], which has a metal treatment layer having an alloy consisting of two or more metals selected from nickel, copper, zinc, molybdenum and tin.

[5]

The silane Si element amount to be contained in the coupling agent layer 0.5μg / dm ² or more 15μg / dm ² is less than [1] to [4] wherein any one of surface-treated copper foil for printed wiring board according to the.

[6]

The silane coupling agent is at least one selected from the group consisting of an epoxy group, an amino group, a vinyl group, a (meth) acryloyl group, a styryl group, a ureide group, an isocyanurate group, a mercapto group, a sulfide group, and an isocyanate group Treated copper foil for a printed wiring board according to any one of [1] to [5], which has a functional group of the following formula

[7]

A copper clad laminate for a printed wiring board in which a resin layer is laminated on the surface of the silane coupling agent layer of the surface-treated copper foil for a printed wiring board according to any one of [1] to [6].

[8]

A printed wiring board using the copper clad laminate for a printed wiring board according to [7].

The surface-treated copper foil for a printed wiring board of the present invention is used for a conductor circuit of a printed wiring board. The copper foil for a printed wiring board according to the present invention highly suppresses the transmission loss when a high frequency signal of GHz band is transmitted and exhibits high adhesion between the copper foil and the resin substrate and excellent durability , And a printed wiring board excellent in visibility can be obtained.

By using the copper clad laminate for printed wiring boards of the present invention as a substrate of a printed wiring board, the transmission loss at the time of transmitting a high frequency signal of GHz band is highly suppressed, the adhesion between the copper foil and the resin substrate is high and the durability is excellent , And a printed wiring board excellent in visibility can be obtained.

The printed wiring board of the present invention is highly resistant to transmission loss when a high frequency signal of GHz band is transmitted, has high adhesion between the copper foil and the resin base material, has excellent durability, and is also excellent in visibility.

These and other features and advantages of the present invention will become more apparent from the following description, with reference to the accompanying drawings appropriately.

Fig. 1 is an explanatory diagram showing an example of a method for measuring the height of the coarse particles.
2 is an explanatory view showing an example of a method for measuring the height of the coarse particles.

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

[Surface-treated copper foil for printed wiring board]

The surface-treated copper foil for a printed wiring board of the present invention (hereinafter referred to as " surface-treated copper foil of the present invention ") is a copper foil obtained by subjecting a surface on which coarse particles are formed (That is, having a silane coupling agent layer on the surface on which the roughening particles are formed), the average height of the roughening particles in the surface of the silane coupling agent layer (surface-treated copper foil surface) m or less, a BET surface area ratio of the surface of the silane coupling agent layer is 1.2 or more, and a surface area coefficient (Cms) of the surface of the silane coupling agent layer is 2.0 or more and less than 8.0. In the surface-treated copper foil of the present invention, it is preferable that the surface of the silane coupling agent layer has an average height of coarse grains measured on the surface of not less than 0.05 탆 and less than 0.5 탆, a BET surface area ratio of the surface of not less than 1.2, Is not less than 2.0 but less than 8.0 is simply referred to as " harmonized surface ". It is preferable that the roughened surface is entirely covered with a silane coupling agent. However, as long as the effect of the present invention is attained, a part of the roughened surface may not be covered with a silane coupling agent (that is, A part of the silane coupling agent layer on the roughened surface may have a film defect, and such a form is also included in the "having a silane coupling agent layer" in the present invention.

In the surface-treated copper foil of the present invention, at least one surface may be a roughened surface, and both surfaces may be roughened. In the surface-treated copper foil of the present invention, usually only one side is a roughened surface.

In the surface-treated copper foil of the present invention, the roughened surface has a BET surface area ratio of at least 1.2, although the average height of the roughed grains is as low as less than 0.5 mu m. Therefore, when the surface-treated copper foil and the resin layer are laminated via the roughened surface to prepare a copper clad laminate, the anchoring effect of the roughened particles and the large surface area are matched to each other, the adhesion between the copper foil and the resin layer becomes extremely high, An excellent copper clad laminate can be obtained. In addition, the roughened surface has a low average height of roughened particles of less than 0.5 mu m, and can reduce the influence of the presence of harmful particles on the length of the transmission path. Therefore, even when a high-frequency signal of GHz band is transmitted to the conductor circuit using the copper clad laminate, transmission loss can be effectively suppressed.

Until now, a method of increasing the BET surface area ratio to 1.2 or more, while forming small coarsened particles having an average height of less than 0.5 占 퐉 on the surface of the copper foil, is unknown. Under such circumstances, the present inventors succeeded in producing copper foil surfaces having coarse particles having an average height of 0.05 μm or more and less than 0.5 μm and a BET surface area ratio of 1.2 or more, by employing the specific harmonious plating treatment conditions described later, Thereby completing the present invention.

The average height of the coarsely grained particles on the roughened surface is preferably 0.05 m or more and less than 0.5 m, more preferably 0.05 m or more and less than 0.3 m, from the viewpoint of more effectively reducing the transmission loss while maintaining high adhesiveness with the resin base material More preferable.

In the present invention, it is preferable that the coarsely grained particles are uniformly formed on the entire roughened surface. The average height of the harmonic grains is measured by the method described in Examples described later.

The BET surface area ratio is calculated based on a method of measuring the surface area by the BET method. That is, the BET surface area ratio is determined by adsorbing gas molecules whose adsorption occupancy area is already known on the sample surface, determining the surface area (BET measurement surface area) of the sample based on the adsorption amount, Is a ratio of the surface cut-off area obtained by subtracting the surface area (cutout area of the sample) assuming that there is no cut-out area, and is measured by the method described in the following embodiments.

In the surface-treated copper foil of the present invention, the BET surface area ratio of the roughened surface means that the larger the value, the larger the surface area. Therefore, the larger the BET surface area ratio of the roughened surface is, the higher the interactivity with the resin becomes, and the better the anchoring effect of the roughening particles, the better the adhesion between the copper foil and the resin layer when the resin layer is laminated. 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 by the laser microscope generally used in the measurement of the surface area of the copper foil, it is impossible in principle to measure the portion which becomes "shaded" in which the laser beam does not touch due to the shape of the coarse particles, It is also difficult to detect the surface area with high sensitivity. For example, even if the height and the diameter are the same as the coarse particles, the coarse grains having a tapered root portion and the non-coarse grains are electrons having a large area in close contact with the resin. In the surface area measurement using a laser microscope, .

In comparison with this, in the measurement of the surface area by the BET method, since the surface area is measured by adsorption of gas molecules, it is possible to measure a portion where the sensitivity to fine irregularities is high and the laser light becomes "shaded". Therefore, the surface area of the sample on which the coarse particles are formed can be measured with higher accuracy than with a laser microscope.

The present inventors succeeded in further increasing the ratio of the surface area of the "shaded portion" or the fine uneven portion which can not be measured by the laser microscope by performing the specific harmonious plating process described later. As a result, the average height of the roughening particles can be suppressed, the transmission loss when the high-frequency signal is transmitted can be effectively suppressed, the adhesion with the resin base material can be greatly increased, and the visibility of the resin base material after etching can be kept good And the present invention has been completed.

The Cms is a ratio of a surface area ratio measured by a BET method to a surface area ratio measured by a laser microscope, and is a numerical value of the ratio of the surface area of the "shadow" portion or the fine irregular portion that can not be measured by a laser microscope. The details of the calculation method of Cms are as described in the following embodiments. In the surface-treated copper foil of the present invention, the Cms of the roughened surface is 2.0 or more and less than 8.0. By setting the average height of harmonic grains on the roughened surface and the BET surface area ratio of the roughened surface within the range specified in the present invention and setting the Cms of the roughened surface to be less than 2.0 and less than 8.0, It is possible to maintain the visibility (permeability) of the resin after the etching well, while enhancing the adhesion to the substrate to a high degree. 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 are different from each other in the principle of measurement of the surface area, 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 brightness index L ^* (Lightness) of the roughened surface is preferably 40 or more and less than 60, and more preferably 40 or more and 55 or less. In the so-called blackening treatment, a treatment surface of a brown to black color (a surface on which an alloy or a copper oxide is formed) tends to have a small L ^* and a high transmission loss. On the other hand, if the shape of the coarsely grained particles is rounded, L ^* tends to rise and the adhesion with the resin base tends to be lowered. L ^* is measured by the method described in the following Examples.

In the surface-treated copper foil of the present invention, the surface on which the roughening particles are formed before the treatment with the silane coupling agent is at least one selected from the group consisting of chromium (Cr), iron (Fe), cobalt (Co), nickel (Ni) ), Molybdenum (Mo), and tin (Sn), or a metal-treated layer having at least one metal selected from chromium, iron, cobalt, nickel, copper, zinc, molybdenum, and tin It is preferable to have a metal treatment layer having an alloy made of at least two kinds of metals. This metal treatment layer is formed of a metal having a metal treatment layer having at least one kind of metal selected from nickel, zinc and chromium, or a metal having an alloy made of at least two metals selected from nickel, zinc and chromium It is more preferable to have a treatment layer.

The copper clad laminate or the printed wiring board using the surface-treated copper foil of the present invention is subjected to heat many times such as a bonding step between the resin and the copper foil or a soldering process in the production step. By this heat, the copper is diffused to the resin side to lower the adhesion between the copper and the resin. By providing the metal treatment layer, diffusion of copper can be prevented, and high adhesion with the resin substrate can be stably . The metal constituting the metal treatment layer also functions as a rust preventive metal for preventing 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 coarse particles are formed before the silane coupling agent treatment. In other words, when the amount of nickel adhered is large, the rust of copper is hardly generated and the adhesion with the resin at high temperature tends to be improved. However, nickel is liable to remain after etching and sufficient insulation reliability is hardly obtained. When the surface-treated copper foil of the present invention has a metal-treated layer, it is preferable that the amount of the nickel element in the roughened surface is 0.1 mg / dm ² or more and less than 0.3 mg / dm ² .

[Production of surface-treated copper foil for printed wiring board]

<Copper>

The copper foil to be used in the production of the surface-treated copper foil of the present invention can be selected depending on the application and other purposes, such as rolled copper foil and electrolytic copper foil. The thickness of the copper foil used in the surface-treated copper foil of the present invention is not particularly limited and may be suitably selected in accordance with the purpose. The thickness is usually 4 to 120 占 퐉, preferably 5 to 50 占 퐉, and more preferably 6 to 18 占 퐉.

<Harmonious plating treatment>

In the production of the surface-treated copper foil of the present invention, the roughened surface can be formed by applying a specific roughening treatment condition. That is, the present invention is based on discovering that the present inventors can form the above-mentioned roughened surface by carrying out electroplating treatment under specific conditions to be described later within a specific range of molybdenum concentration .

(Condition for harmonious plating treatment)

In order to enable the formation of 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 harmful plating process (electroplating process). When the concentration of molybdenum is less than 50 mg / L, problems such as dropping of the powder (grain) are liable to occur. When the concentration exceeds 600 mg / L, the surface after the treatment with the silane coupling agent To 1.2 or more.

In order to enable the formation of the roughened surface, it is necessary to set the inter-pole (inter-pole) flow rate to 0.15 m / sec to 0.4 m / sec in the roughening treatment. If the inter-pole flow rate is less than 0.15 m / sec, the hydrogen gas generated on the copper foil does not progress, and the effect of molybdenum is hard to be obtained, and problems such as dropping of powder (grain) are likely to occur. If the inter-pole flow velocity exceeds 0.4 m / sec, the supply of copper ions to the fine recesses excessively proceeds, the recesses are buried by plating, and it becomes difficult to increase the BET surface area ratio of the surface after the silane coupling agent treatment to 1.2 or more .

In order to enable formation of the roughened surface, it is preferable that the value obtained by multiplying the current density by the processing time in the roughening treatment is set to 20 (A / dm ² ) · sec to 250 (A / dm ² ) need. If this value is less than 20 (A / dm ² ) 占 seconds, it becomes difficult to make the average height of the coarsened grains of the roughened surface to be 0.05 탆 or more after the silane coupling agent treatment, so that sufficient adhesion with the resin to be laminated is ensured It becomes difficult to do. In addition, if it exceeds 250 (A / dm ² ) · sec, it becomes difficult to make the average height of the formed harmonic grains less than 0.5 μm, so that the transmission loss tends to deteriorate. It is preferable that the value obtained by multiplying the current density by the treatment time is less than 160 (A / dm ² ) · sec. From 20 (A / dm ² ) · sec.

(A / dm ² ) / sec} / (mg / L), which is obtained by dividing the value obtained by multiplying the current density by the treatment time by the Mo concentration in the harmonious plating treatment, (A / dm ² ) 占 seconds} / (mg / L) or more. If this value is less than 1.0 (A / dm ² ) sec} / (mg / L), it becomes difficult to obtain a sufficient BET surface area ratio while satisfying other properties. If this value is more than 3.0 ((A / dm ² ) 占 seconds} / (mg / L), it becomes difficult to make Cms less than 8.0. The value obtained by dividing the value obtained by multiplying the current density by the treatment time by the Mo concentration is not less than 1.2 {(A / dm ² ) · seconds} / (mg / L) or more and 2.4 {(A / dm ² ) / L).

Preferable conditions for coarsening plating for enabling formation of the roughened surface are shown below.

- Condition for harmonious plating treatment -

Cu: 10 to 30 g / L

H ₂ SO ₄ : 100-200 g / L

Bath temperature: 20 ~ 30 ℃

Mo concentration: 50 to 600 mg / L

Inter-pole flow rate: 0.15 ~ 0.4m / sec

Current density: 15 to 70 A / dm ²

Processing time: 0.1 to 10 seconds

Current density x processing time: 20 to 250 (A / dm ² )

Current density × processing time ÷ Mo concentration: 1.0 ~ 3.0 {(A / dm 2) · sec} / (mg / L)

The addition of molybdenum to the plating solution is a form in which molybdenum dissolves as ions and is not particularly limited so long as it does not change the pH of the copper sulfate plating solution or contain metal impurities incorporated into the copper plating film. For example, an aqueous solution of a molybdate (for example, sodium molybdate or potassium molybdate) may be added to the copper sulfate plating solution.

<Metal Treatment Layer>

When the surface-treated copper foil of the present invention has a metal treatment layer, the method for forming the metal treatment layer is not particularly limited and can be formed by a conventional method. For example, in the case of forming a metal treatment layer having nickel, zinc and chromium, nickel plating, zinc plating and chromium plating are carried out in this order, for example, under the following conditions. .

(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 ℃

Current density: 1 to 50 A / dm ²

Processing 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 ℃

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 ℃

Current density: 0.1 to 10 A / dm ²

Processing time: 1 second to 2 minutes

pH: not more than 3.0

Surface-treated copper foil of the present invention is preferably present Si element amount (i.e., Si element amount to be contained in the silane coupling agent layer) is 0.5μg / dm ² or more 15μg / dm ² is less than that in the surface roughening treatment. Is written as the Si element amount of less than 0.5μg / dm ² or more 15μg / dm ^2, while suppressing the amount of the silane coupling agent, it can improve the adhesion to the resin effectively. Si element amount to be contained in the silane coupling agent layer is, more preferably, 3μg / dm ² or more and 15μg / dm less than ^2, more preferably from 5μg / dm ² or more and less than 15μg / dm ^2.

The silane coupling agent is appropriately selected according to the molecular structure (kind of functional group, etc.) of the resin constituting the resin layer to be laminated with the surface-modified copper foil of the present invention. Among them, the silane coupling agent is preferably at least one selected from an epoxy group, an amino group, a vinyl group, a (meth) acryloyl group, a styryl group, a ureide group, an isocyanurate group, a mercapto group, a sulfide group and an isocyanate group It is preferable to have one kind of functional group. The term "(meth) acryloyl group" means "acryloyl group and / or methacryloyl group".

The treatment of the surface of the copper foil on which the coarse particles are formed with the silane coupling agent can be carried out by a conventional method. For example, a solution (coating liquid) of a silane coupling agent is prepared, and the coating liquid is applied to the surface of the copper foil on which the coarse particles are formed and dried, whereby the surface of the copper foil on which the coarse particles are formed is adsorbed . As the coating liquid, 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 method of applying the coating liquid. For example, the coating liquid is uniformly flowed on the surface on which the coarse particles are formed in a state where the copper foil is obliquely, and a liquid is drained by using a roll The film can be coated by applying a coating liquid to a copper foil adhered with the surface on which the coarse particles are formed in a downward direction (downward) between the rolls, draining the solution into rolls, and then heating and drying . The coating temperature is not particularly limited, and is usually 10 to 40 占 폚.

[Copper clad laminate for printed wiring board]

The copper clad laminate for a printed wiring board of the present invention (hereinafter referred to as "copper clad laminate of the present invention") has a structure in which a resin layer (resin base) is laminated on the roughened surface of the surface-treated copper foil of the present invention . The resin layer is not particularly limited, and a resin layer which is usually used for a copper clad laminate for manufacturing a printed wiring board can be employed. For example, a halogen-free low-dielectric substrate used in a rigid substrate or a low-dielectric polyimide commonly used in a flexible substrate can be used.

The method for laminating the surface-treated copper foil and the resin base material is not particularly limited. For example, the copper foil and the resin base material can be adhered to each other by a heat press molding method using a hot press machine. The press temperature in the thermo-compression molding method is preferably about 150 to 400 캜. The press pressure is preferably set to about 1 to 50 MPa.

The thickness of the copper clad laminate is preferably 10 to 1000 占 퐉.

[Printed circuit board]

The printed wiring board of the present invention is manufactured using the copper clad laminate of the present invention. That is, the copper-clad laminate according to the present invention can be obtained by performing a treatment such as etching to form a conductor circuit pattern and, if necessary, forming or mounting other structures by a conventional method.

Example

Hereinafter, the present invention will be described in more detail based on examples. In addition, the following is an example of the present invention, and various forms can be employed in the practice of the present invention within the scope of not deviating from the gist of the present invention.

[Production of copper foil]

An electrolytic copper foil or a rolled copper foil was used as a copper foil to be a substrate for carrying out the roughening treatment.

In Examples 1, 2, 4, 5, 7 and 8, and Comparative Examples 1 to 4 and 7 and Reference Example 1, an electrolytic copper foil having a thickness of 12 탆 was used, which was produced under the following conditions.

&Lt; Preparation conditions of electrolytic copper foil &

CuSO ₄ : 280 g / L

H ₂ SO ₄ : 70 g / L

Chlorine concentration: 25 mg / L

Bath temperature: 55 ℃

Current density: 45 A / dm ²

(additive)

Sodium 3-mercapto-1-propanesulfonate: 2 mg / L

Hydroxyethylcellulose: 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 sheet (manufactured by UACJ Co., Ltd.) was subjected to a degreasing treatment under the following conditions.

<Condition for degreasing treatment>

Degreasing solution: An aqueous solution of Cleaner 160S (manufactured by Meltex Inc.)

Concentration: 60 g / L aqueous solution

Bath temperature: 60 ℃

Current density: 3A / dm ²

Power-on time: 10 seconds

[Formation of Harmonized Surface]

A roughened surface was formed on one side of the copper foil by electroplating. The surface to be roughened plating was formed by setting the concentration of molybdenum as shown in Table 1 below and using the intercooled flow rate, the current density and the treatment time as shown in Table 1 below, using the following coarse plating bath basic bath composition did. The molybdenum concentration was adjusted by adding an aqueous solution of sodium molybdate dissolved in pure water to the basic bath.

&Lt; Basic bath composition of harmony plating solution >

Cu: 25 g / L

H ₂ SO ₄ : 180 g / L

Bath temperature: 25 ℃

<Formation of Metal Treatment Layer>

Subsequently, the surface subjected to the harmonious plating was subjected to metal plating in the order of Ni, Zn, and Cr in the following conditions to form a metal-treated layer. In addition, the metal treatment layer was not formed in Reference Example 1.

<Ni plating>

Ni: 40 g / L

H ₃ BO ₃ : 5 g / L

Bath temperature: 20 ℃

pH: 3.6

Current density: 0.2 A / dm ²

Power-on time: 10 seconds

<Zn plating>

Zn: 2.5 g / L

NaOH: 40 g / L

Bath temperature: 20 ℃

Current density: 0.3 A / dm ²

Power-up time: 5 seconds

<Cr plating>

Cr: 5 g / L

Bath temperature: 30 ℃

pH: 2.2

Current density: 5 A / dm ²

Power-up time: 5 seconds

&Lt; Application of silane coupling agent (Formation of roughened surface) >

A commercially available silane coupling agent solution (30 占 폚) as shown in Table 2 was applied to the entire surface of the metal treatment layer, and excess liquid drainage was performed by squeegee, followed by drying at 120 占 폚 under atmospheric pressure for 30 seconds. A method for preparing a solution of each silane coupling agent is as follows.

3-glycidoxypropylmethyldimethoxysilane (KBM-402 manufactured by Shin-Etsu Chemical Co., Ltd.): A 0.3 wt% solution was prepared with pure water.

3-Aminopropyltrimethoxysilane (KBM-903 manufactured by Shin-Etsu Chemical Co., Ltd.): 0.25 wt% solution was prepared with pure water.

Vinyltrimethoxysilane (KBM-1003 manufactured by Shin-Etsu Chemical Co., Ltd.): 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.): 0.25 wt% solution was prepared with a solution adjusted to pH 3 by adding sulfuric acid to pure water.

3-isocyanate propyltriethoxysilane (KBE-9007, Shin-Etsu Chemical Co., Ltd.): 0.2 wt% solution was prepared by adding sulfuric acid to pure water and adjusting the pH to 3.

3-ureide propyltriethoxysilane (KBE-585 manufactured by Shin-Etsu Chemical Co., Ltd.): A 0.3 wt% solution was prepared by mixing 1: 1 of ethanol and pure water.

[Measurement of average height of harmonic particles]

The average height of the roughed grains in 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 an SEM image of a cross section parallel to the thickness direction of the roughened surface (surface after the silane coupling agent treatment) of the surface-treated copper foil prepared in Comparative Example 6. Fig. Likewise, on the cross section of each copper foil, SEM observation was performed randomly for five different visual fields at a magnification that allows confirmation of the two heads and bottom portions of the coarse grains in the field of view and including about 10 coarse grains. The heights of the coarsened grains having the highest height were measured for each of five visual fields of one copper foil and the average of the obtained five measured values (maximum value) was taken as the average height of the coarsened particles on the roughened surface of the copper foil.

A method of measuring the height of harmonic particles will be described in detail with reference to the drawings. As shown in Fig. 1, the coarse particles to be measured are arranged such that the shortest distance between a straight line connecting a leftmost and rightmost bottom portion (a straight line connecting point a and point b) The shortest distance between the two points (point c) of the point A and the straight line connecting point a and point b is the height H of the coarsened particles.

2 is an SEM image of a cross section parallel to the thickness direction of the roughened surface (surface after the silane coupling treatment) of the surface-treated copper foil prepared in Example 2. Fig. When the coarsely grained particles are formed in such a manner as to branch off, the whole including the branched structure is regarded as one coarsely grained particle. That is, the two points (f point) and d point of the coarse particles and the point (d) of the coarse particles having the longest distance from the straight line connecting the left and right lowermost portions of the coarse particles formed in resin form The shortest distance from the straight line connecting the points was defined as the height H of the harmonic grains.

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 (BET measurement surface area) of the roughened surface measured by the BET method by the sample cutout area that is the area seen from the plane.

The BET measurement surface area was measured by a krypton gas adsorption BET multi-point method using a gas adsorption pore distribution measuring apparatus ASAP 2020 manufactured by Micromeritics Japan. Prior to the measurement, the pre-treatment was carried out under reduced pressure drying at 150 占 폚 for 6 hours.

The sample (copper foil) to be used for the measurement was cut out into 3 m ² of approximately 3 g, cut into 5 mm squares, and 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, the surface area of only the surface of the surface-treated copper subjected to the roughening treatment on one surface can not be measured. Here, the BET surface area ratio A was actually calculated by the following formula.

<BET surface area ratio A>

The BET surface area ratio A was calculated by the following equation, assuming that the surface area ratio of the surface on which the roughening treatment was not performed (the surface opposite to the roughened surface) was equal to 1, that is, the sample cutout area.

(BET surface area ratio A) = [(BET measurement surface area) - (sample cutout area)] / (sample cutout area)

Further, in the surface area measurement of the BET method, the surface area of the surface (side surface) other than the roughened surface and the surface not subjected to roughening treatment is also measured. However, at the thin thickness (for example, The aspect ratio of the area occupied by the entire plane is very small and can be ignored in practice.

In the case where the surface is not roughened as in Reference Example 1, the BET measurement surface area may be smaller than the cutout area due to the measurement principle of the BET method (that is, the BET surface area ratio A is less than 1 There is work. On the other hand, when the surface having fine irregularities is formed by the roughening treatment, it is possible to detect fine irregularities with high sensitivity by applying the BET method, and as a result, the BET surface area ratio A exceeds 1.

[Measurement of laser surface area ratio B]

The laser surface area ratio B was calculated based on the surface area measurement using a laser microscope VK8500 (manufactured by KEYENCE CORPORATION.). To be more specific, the roughened surface of the sample (copper foil), the observation times magnification of 1000, and measuring a three-dimensional surface area of the area of 6550μm ² portions in a plan view, written by dividing the three-dimensional surface area to 6550μm ^2, a laser surface area The ratio B was obtained. The measurement pitch was set to 0.01 mu m. The results are shown in Table 3.

[Calculation of fine surface coefficient Cms]

The fine surface coefficient Cms was calculated based on the BET surface area ratio A and the laser surface area ratio B on the basis of the following equation. 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 (mu g / dm &lt; ² &gt;) in the roughened surface (i.e., the amount of Si element contained in the silane coupling agent layer) was masked with the coating material on the surface not subjected to the roughening treatment of the sample, , Only the surface portion was dissolved by a mixed acid heated to 80 DEG C (nitric acid 2: hydrochloric acid 1: pure water 5 (volume ratio)), and the Si mass in the obtained solution was measured at an atom of Hitachi High-Tech Science Corporation And quantitatively analyzed by atomic absorption spectrometry using a spectrophotometer (model: Z-2300). The results are shown in Table 3 below as the amount of Si element.

[Measurement of lightness index L ^* ] [

The lightness index L ^* is an L ^* in the color space L ^* a ^* b ^* as defined in JIS-Z8729. An ultraviolet visible spectrophotometer V-660 (an integrating sphere unit) manufactured by Nihon Bunko Co., Ltd. was used for the measurement of the brightness index L ^* . The total light ray spectral reflectance of the roughened surface was measured at a wavelength of 870 to 200 nm. From the obtained spectrum, the brightness index L ^* value was calculated by the software provided with the measuring apparatus, and it is shown in Table 3.

[Evaluation of high-frequency characteristics]

As an evaluation of the high frequency characteristics, the transmission loss to the high frequency band was measured. The roughened surface (surface treated with the silane coupling agent) of the surface-treated copper foil having the roughened surface prepared in each of the above Examples and Comparative Examples was applied to a polyphenylene ether-based low dielectric constant A copper clad laminate was produced by pressing two sheets of the resin substrate MEGTRON6 (thickness 50 to 100 mu m) under the conditions of surface pressure 3 MPa and 200 DEG C for 2 hours. The obtained laminate was subjected to circuit processing, and MEGTRON6 was further laminated thereon to finally form a three-layer copper clad laminate. A microstrip line having a width of 100 m and a length of 40 mm was formed in the transmission line. In this transmission line, a high-frequency signal up to 100 GHz was transmitted using a network analyzer, and transmission loss was measured. The characteristic impedance was 50 Ω.

The measurement of the transmission loss means that the smaller the absolute value is, the lower the transmission loss and the better the high-frequency characteristic. Table 4 shows the evaluation results of transmission loss at 20 GHz and 70 GHz. The evaluation criteria are as follows.

<Evaluation Criteria for Transmission Loss at 20 GHz>

◎: transmission loss is -6.2 dB or more

○: From transmission loss less than -6.2 dB to more than -6.5 dB

×: transmission loss less than -6.5 dB

<Evaluation criteria of transmission loss at 70 GHz>

◎: transmission loss is -20.6 dB or more

?: -24.0 dB or more from a transmission loss of less than -20.6 dB

X: Less than -24.0 dB

Further, on the basis of the evaluation result of the transmission loss, the high frequency characteristics were evaluated based on the following evaluation criteria. The results are shown in Table 4 below.

<General evaluation criteria for high frequency characteristics>

◎ (Good): The evaluation results of transmission loss of 20 GHz and transmission loss of 70 GHz are all ◎.

(Positive): The evaluation result of the transmission loss at 20 GHz is ⊚, and the evaluation result of the transmission loss at 70 GHz is ◯.

(Pass): The evaluation result of the transmission loss at 70 GHz is x, but the transmission loss at 20 GHz is ⊚ or ◯.

× (Failed): The evaluation results of transmission loss of 20 GHz and transmission loss of 70 GHz are all ×.

[Evaluation of visibility]

The haze value (haze value) was measured as an evaluation of visibility. The roughened surface of the sample prepared in Examples and Comparative Examples was applied as a resin adhering surface and adhered to both surfaces of a PIXEO (FRS-522, thickness 12.5 m) as a polyimide for a laminate made by Kaneka Corporation. A copper clad laminate was produced. With respect to these copper-clad laminated sheets, the copper foil bonded to both surfaces was removed by etching with an aqueous solution of copper chloride to prepare a sample film for haze measurement.

The haze of the produced sample film was measured based on the method described in JIS K7136: 2000 using an ultraviolet visible spectrophotometer V-660 (integral sphere unit) manufactured by Nihon Bunko. (Tt: total light transmittance, Td: diffusion transmittance) was calculated as the haze value (Td / Tt) × 100 (%).

The haze value indicates the degree of cloudiness of the sample film, and the smaller the numerical value, the lower the degree of fogging and the better the visibility. The visibility was evaluated based on the following evaluation criteria. The results are shown in Table 4 below.

<Evaluation criteria of visibility>

⊚: Haze value is less than 30%

○: Haze value is 30% or more and less than 60%

?: Haze value is 60% or more and less than 80%

×: haze value of not less than 80%

If the visibility is ⊚, ◯ or △, it can be said that visibility is practically acceptable.

[Evaluation of Adhesion-1]

The adhesion was evaluated by peeling test. A copper clad laminate was prepared in the same manner as the copper clad laminate produced in the above [evaluation of high frequency characteristics], and the copper clad part of the obtained copper clad laminate was masked with a 10 mm wide tape. The copper-clad laminate was subjected to copper chloride etching, and then the tape was removed to prepare a circuit board having a width of 10 mm. A circuit wiring portion (copper foil portion) having a width of 10 mm on the circuit board was peeled off from the resin substrate at a rate of 50 mm / min in a direction of 90 degrees using a tensile tester manufactured by Toyo Seiki Seisakusho Co., The peel strength was measured. Using the obtained measurement value as an index, the adhesiveness was evaluated based on the following evaluation criteria. In addition, the MEGTRON6 resin contributes more to the adhesion than the PIXEO resin in the anchor effect. The results are shown in Table 4 below.

<Evaluation Criteria of Adhesion>

?: Peel strength of 0.6 kN / m or more

DELTA: Peel strength of 0.5 kN / m or more and less than 0.6 kN / m

X: Peel strength less than 0.5 kN / m

[Evaluation of adhesion 2]

A copper clad laminate was prepared in the same manner as the copper clad laminate produced in [Evaluation of visibility], and the copper clad part of the obtained copper clad laminate was masked with a 10 mm wide tape. The copper clad laminate was subjected to copper chloride etching, and then the tape was removed to prepare a circuit board having a width of 10 mm. The peeling strength when the circuit wiring portion (copper foil portion) of 10 mm in width of this circuit wiring was peeled off from the resin base material at a rate of 50 mm / min in the 90 degree direction was measured using a tensile tester of Toyosaka Seisakusho Co., Respectively. Using the obtained measurement value as an index, the adhesiveness was evaluated based on the following evaluation criteria. The results are shown in Table 4 below.

<Evaluation Criteria of Adhesion>

?: Peel strength of 1 kN / m or more

X: peel strength less than 1 kN / m

Further, on the basis of the evaluation results of the adhesion, the adhesiveness was evaluated based on the following evaluation criteria. The results are shown in Table 4 below.

<Adhesiveness Overall Evaluation Standard>

⊚ (Good): The evaluation results of [adhesion evaluation 1] and [adhesion evaluation 2] described above are ◯.

(Pass): The evaluation result of [Adhesion evaluation-1] is?, And the evaluation result of [Adhesion evaluation-2] is?.

× (rejection): The evaluation result of at least one of the [evaluation of adhesion-1] and the [adhesion evaluation-2] described above is X.

[Overall evaluation]

All of the above-described high-frequency characteristics, visibility and adhesiveness were integrated and evaluated based on the following evaluation criteria.

<Evaluation Criteria of Overall Evaluation>

A (good): The results of the comprehensive evaluation of high-frequency characteristics, the evaluation of visibility and the evaluation of adhesion are both ◎.

B (Pass): Although A is not satisfied, there is no X in the result of comprehensive evaluation of high-frequency characteristics, evaluation of visibility, and evaluation of adhesion.

C (rejection): At least one evaluation result of the comprehensive evaluation of high-frequency characteristics, the evaluation of visibility, and the evaluation of adhesion is x.

The results shown in the above tables will be discussed.

Comparative Example 1 is an example in which the average height of the harmonic grains existing on the roughened surface of the surface-treated copper foil is smaller than that specified in the present invention. When the copper clad laminate was produced by using the surface-treated copper foil of Comparative Example 1, the adhesion between the copper foil and the resin substrate was poor.

In Comparative Examples 2, 3 and 7, both the BET surface area ratio and the Cms of the roughened surface of the surface-treated copper foil are smaller than those specified in the present invention. When the copper-clad laminated boards were produced by using the surface-treated copper foils of Comparative Examples 2, 3 and 7, adhesion between the copper foil and the resin substrate was deteriorated.

In Comparative Examples 4 and 5, the average height of the harmonic grains existing on the roughened surface of the surface-treated copper foil is larger than that specified in the present invention. When the copper-clad laminate was produced by using the surface-treated copper foils of Comparative Examples 4 and 5 and a conductor circuit was formed, both the high-frequency characteristics and the visibility were significantly lowered.

Comparative Example 6 is an example in which Cms is smaller than that specified in the present invention. When the copper-clad laminate was produced using the surface-treated copper foil of Comparative Example 6, the adhesion of the MEGTRON 6 resin, which contributed greatly to the anchor effect to the adhesion, was poor.

Reference Example 1 is an example in which the roughening treatment is not performed on the copper foil, and neither the metal treatment layer nor the silane coupling agent treatment is performed. When the copper clad laminate was produced by using the copper foil of Reference Example 1, the adhesion between the copper foil and the resin substrate was greatly reduced.

In contrast to this, when the average height of the coarse grains formed on the roughened surface of the surface-treated copper foil is within the range specified in the present invention and the BET surface area ratio and Cms of the roughened surface are also in the range of the present invention When the copper clad laminate was produced using the surface-treated copper foil of Examples 1 to 8, the adhesion between the copper foil and the resin substrate was excellent. The conductor circuits formed from the copper-clad laminated boards using the surface-treated copper foils of Examples 1 to 8 effectively suppressed the transmission loss even when a high-frequency signal was transmitted. Further, the surface-treated copper foils of Examples 1 to 8 were laminated and adhered to each other The base material exhibited good visibility when the copper foil was thereafter removed by etching.

The present application is based on Japanese patent application 2015-240007 filed in Japan on Dec. 9, 2015, which is incorporated herein by reference and its contents as part of the description of this specification.

Claims (8)

A surface-treated copper foil for a printed wiring board having a silane coupling agent layer on a surface on which roughening particles are formed,
Wherein the average height of the roughening particles in the surface of the silane coupling agent layer is 0.05 탆 or more and less than 0.5 탆,
Wherein the BET surface area ratio of the surface of the silane coupling agent layer is 1.2 or more and the fine surface coefficient Cms is 2.0 or more and less than 8.0. The method according to claim 1,
Wherein the average height of the roughening particles on the surface of the silane coupling agent layer is from 0.05 mu m or more to less than 0.3 mu m. 3. The method according to claim 1 or 2,
The silane coupling agent layer on the surface, L ^* a ^* b ^* color system of table L ^* is 40 or more is less than 60, surface-treated copper foil for printed wiring board according to. 4. The method according to any one of claims 1 to 3,
Wherein the surface on which the roughening particles are formed has a metal treatment layer having at least one metal selected from the group consisting of chromium, iron, cobalt, nickel, copper, zinc, molybdenum and tin, A surface treated copper foil for a printed wiring board having a metal treatment layer having an alloy made of at least two metals selected from nickel, copper, zinc, molybdenum, and tin. 5. The method according to any one of claims 1 to 4,
The silane coupling Si element amount is 0.5μg / dm ² or more 15μg / dm ² below, the surface treated copper foil for printed wiring board to be contained in the agent layer. 6. The method according to any one of claims 1 to 5,
The silane coupling agent is at least one selected from the group consisting of an epoxy group, an amino group, a vinyl group, a (meth) acryloyl group, a styryl group, a ureide group, an isocyanurate group, a mercapto group, a sulfide group, and an isocyanate group Of the surface-treated copper foil for a printed wiring board. A copper clad laminate for a printed wiring board comprising a surface-treated copper foil for a printed wiring board according to any one of claims 1 to 6, wherein a resin layer is laminated on the surface of the silane coupling agent layer. A printed wiring board using the copper clad laminate for a printed wiring board according to claim 7.

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