KR102274906B1 - Copper foil and copper clad laminate having the same - Google Patents

Abstract

An object of the present invention is to provide a copper foil capable of realizing excellent adhesion, transmission characteristics and heat resistance, and a copper clad laminate using the same. When the characteristic of the bonding surface of copper foil is expressed by the undulation number Wn calculated from the roughness motif determined by the motif method prescribed in JIS B0631:2000 and the roughness motif average depth R, the wavy number Wn is 11 to 30 pieces/mm , Further, the roughness motif average depth R is 0.20 to 1.10 μm, Copper foil characterized in that.

Description

Copper foil and copper clad laminate having the same

The present invention relates to a copper foil and a copper clad laminate having the same.

In recent years, miniaturization and thinning of electronic devices are progressing, and in particular, various electronic components used in communication devices such as servers, antennas, and mobile phones are highly integrated, and ICs and LSIs with small and high-density printed circuit boards, etc. this is being used

In response to this, high density is also required for circuit wiring patterns in multilayer printed wiring boards for high-density mounting, flexible printed wiring boards, etc. (hereinafter, sometimes simply referred to as printed wiring boards) used for these, and the width and spacing of circuit wirings are reduced. Demand for printed wiring boards with fine circuit wiring patterns, so-called fine patterns, is increasing.

Conventionally, the copper foil used for a printed wiring board makes the surface on the side to be thermocompression-bonded to a resin base material a roughening surface, and exhibits the anchor effect with respect to a resin base material in this roughening surface, and the bonding strength of a resin base material and copper foil is improved. High reliability as a printed wiring board was ensured (for example, patent document 1).

However, in order to improve the information processing speed of electronic devices and to cope with wireless communication, high-speed transmission of electrical signals is required for electronic components, and the application of high-frequency compatible substrates is also progressing. In high-frequency compatible substrates, it is necessary to reduce transmission loss for high-speed transmission of electrical signals, and in addition to lowering the dielectric constant of the resin substrate, it is required to reduce transmission loss of circuit wiring serving as a conductor. In particular, in a high frequency band exceeding several GHz, since the current flowing through circuit wiring is concentrated on the surface of the copper foil due to the skin effect, when the copper foil subjected to the conventional roughening treatment is used for a high frequency compatible substrate, it is roughened. There was a problem in that the transmission loss in the processing unit increased and the transmission characteristics deteriorated.

In order to solve the above-mentioned problems, as a copper foil used for a printed wiring board corresponding to a fine pattern or a high frequency, a smooth copper foil not subjected to a roughening treatment is used, and the method of sticking this to a resin substrate and using it has been studied so far It has been (for example, Patent Documents 2 to 4).

Here, as a method of reducing the roughness of the copper foil surface, the method of plating with the electrolytic plating bath which put the brightening agent in the copper foil surface after foil manufacture is known (patent document 5). Moreover, as a method of obtaining the copper foil which has moderate surface roughness, the method of forming a roughening particle layer by pulse electrolysis is known (patent document 6).

However, although these smooth copper foils and microroughened copper foils are excellent in fine pattern circuit formability and transmission characteristics in a high frequency region, it is difficult to stably and sufficiently increase the adhesion between the copper foil and the resin substrate. did. In particular, when such smooth copper foil was used, there existed a problem that the adhesiveness of copper foil and a resin base material further fell by the manufacturing process of a printed wiring board, or the thermal load during use. Therefore, conventionally, it was common to aim at coexistence of a transmission characteristic and the adhesiveness of copper foil and a resin base material by optimizing roughening of copper foil.

On the other hand, in recent years, high multilayer high frequency substrates exceeding 30 layers have been manufactured, and defects are diversifying due to the complexity of the process accompanying the high multilayering. In particular, in the solder reflow process at the time of mounting various electronic components on a printed wiring board, not only the delamination between resin-copper foil (thermal expansion), but also the delamination between resin and resin frequently. Such delamination between resin and resin is known as a phenomenon in which outgas generated by decomposition of resin upon heating collects in the resin and resin and delaminates due to pressure increase of the outgas. The resin surface of the resin-resin bonding surface has the shape of a replica of the copper foil surface, and since the shape of the copper foil surface affects the easiness of delamination, an appropriate replica is required to suppress the delamination between the resin and the resin. It is important to apply a copper foil having a surface shape from which the shape is obtained. However, in the conventional micro-roughened copper foil and smooth copper foil in which low transmission loss was anticipated, the delamination between resin and resin was not fully suppressed. Moreover, it is thought that the delamination between resin-resin shifts to the interface destruction of resin-copper foil with a raise of a heating temperature, and it became a factor in which circuit wiring peels from a resin base material. Therefore, especially in the printed wiring board corresponding to the fine pattern in which the bonding area of circuit wiring (copper foil) and the resin base material is comprised very small, the yield fall by these delaminations is serious, and the improvement of heat resistance was desired.

Japanese Patent Laid-Open No. 5-029740 Japanese Patent Laid-Open No. 2003-023046 Japanese Patent Laid-Open No. 2007-165674 Japanese Patent Laid-Open No. 2008-007803 Japanese Patent Laid-Open No. 9-272994 Japanese Patent Laid-Open No. 2011-162860

This invention was made in view of the said situation, and an object of this invention is to provide the copper foil which can implement|achieve the outstanding adhesiveness, transmission characteristic, and heat resistance, and the copper clad laminated board which has this.

In the conventional copper foil, from the viewpoint of reducing transmission loss, a smooth copper foil surface with few irregularities is required, and from the viewpoint of adhesion to the resin and heat resistance improvement, a copper foil having a rough shape and a large surface area in contact with the resin It is technical common sense that the surface is calculated|required, and it was common to adjust the surface shape of copper foil with the unevenness|corrugation by the small roughening particle of 0.01-1 micrometer order from these viewpoints. In addition, Ra (arithmetic mean roughness) and Rz (10-point average roughness), which are the evaluation indexes of the copper foil surface shape that have been generally used conventionally, are, on the basis of the calculation principle, the length per each mountain shape on the copper foil surface, per unit length. Information such as the number of mountain shapes or the depth per mountain shape is not included, and these indicators are the copper foil surface shape that causes resin adhesion, heat resistance, and transmission loss in printed wiring board applications requiring higher performance. It was difficult to evaluate the effect of Therefore, in the conventional copper foil evaluated by the above-mentioned index|index, the influence of the undulation in the copper foil surface is not considered, and sufficient transmission loss characteristic is not acquired, or the problem that sufficient heat resistance is not acquired. there was

On the other hand, the present inventors repeated intensive studies on the surface irregularities of copper foil, and focused on relatively macro irregularities such as wavy, rather than fine (micro) irregularities excellent in the conventional anchor effect, as a result, Reduction of transmission loss in a higher frequency region than in the prior art such as when the wave number Wn and the illuminance motif average depth R calculated from the illuminance motif determined by the motif method specified in JIS B0631:2000 are, for example, 40 GHz; It was discovered that a favorable correlation was shown with respect to the improvement of adhesiveness with resin, and heat resistance. And, based on this knowledge, by giving a wave shape of a relatively long wavelength of about tens to 100 μm on the surface of the copper foil, and controlling the depth to a relatively shallow shape of about 0.2 to 1.1 μm, the roughness of the surface of the copper foil is reduced. After keeping the resulting transmission loss small, it discovered that the improvement of adhesiveness with a resin layer and heat resistance could be made compatible very well, and came to complete this invention. The present invention provides, in the bonding surface of the copper foil, by controlling the wavy number Wn and the roughness motif average depth R within a predetermined range, for example, when a printed wiring board is formed, while improving the adhesion between the copper foil and the resin. , it is possible to suppress the deterioration of the transmission characteristics, and also effectively suppress the occurrence of delamination between the resin and the resin during heating.

That is, the summary structure of this invention is as follows.

[1] When the characteristic of the bonding surface of copper foil is expressed by the undulation number Wn calculated from the roughness motif determined by the motif method prescribed in JIS B0631:2000 and the roughness motif average depth R, the number of undulations Wn is 11 to 30 /mm, and the roughness motif average depth R is 0.20 to 1.10 µm, The copper foil characterized in that it is.

[2] The copper foil according to [1], wherein the wavy number Wn is 12 to 27 pieces/mm, and the roughness motif average depth R is 0.30 to 0.90 µm.

[3] The copper foil according to [2], wherein the wavy number Wn is 14 to 22 pieces/mm, and the roughness motif average depth R is 0.40 to 0.80 µm.

[4] The copper according to any one of [1] to [3], wherein the bonding surface has a surface area ratio of an actual three-dimensional surface area to a two-dimensional surface area measured by projection on a plane of 1.05 to 2.85. foil.

[5] The copper foil according to [4], wherein the bonding surface has a surface area ratio of a measured three-dimensional surface area to a two-dimensional surface area measured by projecting onto a plane from 2.00 to 2.70.

[6] The copper foil according to any one of [1] to [5], wherein the copper foil is an electrolytic copper foil.

[7] The copper foil according to any one of [1] to [6], wherein the bonding surface is a matte surface.

[8] The copper foil is a surface-treated copper foil comprising a copper foil substrate and a surface treatment layer on the surface of the copper foil substrate on the bonding surface side;

The surface treatment layer includes at least one of a roughened particle layer, a Ni surface treatment layer, a Zn surface treatment layer, a Cr surface treatment layer, and a silane coupling agent layer,

The copper foil according to any one of [1] to [7], wherein the bonding surface is an outermost surface of the surface treatment layer.

[9] The surface treatment layer includes the Ni surface treatment layer,

The copper foil as described in said [8] whose adhesion amount of Ni is 0.010-0.800 mg/dm<2>.

[10] The copper foil according to the above [9], wherein the adhesion amount of Ni is 0.020 to 0.400 mg/dm 2 .

[11] The surface treatment layer includes the Cr surface treatment layer,

The copper foil according to any one of [8] to [10], wherein the adhesion amount of Cr is 0.010 to 0.300 mg/dm 2 .

[12] The copper foil according to [11], wherein the Cr adhesion amount is 0.015 to 0.200 mg/dm 2 .

[13] A copper clad laminate comprising the copper foil according to any one of [1] to [12], and an insulating substrate adhesively laminated on the bonding surface.

ADVANTAGE OF THE INVENTION According to this invention, it became possible to provide the copper foil which can implement|achieve the outstanding adhesiveness, transmission characteristic, and heat resistance, and the copper clad laminated board which has this.

1 : is a graph which shows the relationship between the roughness motif average depth R and the wave number Wn about the copper foil which concerns on this invention, and the conventional copper foil (conventional example A).
2 : is a schematic sectional drawing which shows the manufacturing procedure of the test piece T2 at the time of performing a reflow heat resistance test in an Example.

<Copper foil>

EMBODIMENT OF THE INVENTION Hereinafter, preferable embodiment of the copper foil of this invention is demonstrated in detail.

In the copper foil according to the present invention, when the characteristics of the bonding surface are expressed by the wavy number Wn calculated from the roughness motif determined by the motif method specified in JIS B0631:2000 and the roughness motif average depth R, the wavy number Wn is 11 to 30 pieces/mm, and the roughness motif average depth R is 0.20 to 1.10 µm.

In this invention, an adhesive surface is the outermost surface of copper foil, and is a surface for adhesively laminating a resin base material. In addition, the bonding surface of copper foil is at least one surface of copper foil, and both surfaces may be sufficient as it. In addition, in this invention, copper foil shall contain the electrolytic copper foil, rolled copper foil, the surface-treated copper foil etc. which surface-treated them, unless it mentions specially. Therefore, for example, when the copper foil of this invention is a surface-treated copper foil provided with a surface-treated layer on the surface of a copper foil base|substrate and this copper foil base|substrate, the adhesion surface becomes the outermost surface of a surface treatment layer. .

The present inventors, paying attention to the relatively macro surface property called "wavy" with respect to the unevenness of the surface of the copper foil, by controlling the wavy properties in the adhesive surface of the copper foil, transmission properties and heat resistance of a previously unprecedented high level It found that it could be realized and came to complete the present invention.

In this invention, in evaluating the waviness of the bonding surface of copper foil, the motif parameter standardized by JIS B 0631:2000 was introduce|transduced. A motif is a curved portion sandwiched between two local mountains, indicated by the motif length and the motif depth. In particular, in this invention, the roughness motif average length AR and roughness motif average depth R prescribed|regulated by the measurement conditions mentioned later are evaluated.

Here, the roughness motif average length AR is an arithmetic mean value of the _{roughness motif length AR i calculated|required by the evaluation length.} That is, it is represented by the following formula (1).

In the formula (1), n is the number of roughness motifs (equivalent to _{the number of AR i ).} In addition, roughness motif length AR _i turns into length A or less.

Further, the average roughness depth R motif, is the arithmetic average of the roughness motif depth H _j obtained by the evaluation length. That is, it is represented by the following formula (2).

In the formula (2), m is the number of _{H j .}

A specific measurement is performed under the following conditions.

First, with respect to the bonding surface of the copper foil, in the TD direction (direction perpendicular to the long side direction (corresponding to the foil making direction) of the copper foil) in a certain range (for example, a straight line range of 50 mm in length), JIS B 0631 Measure the roughness motif average length AR and the roughness motif average depth R according to the provisions of :2000. The measuring device may be any device capable of performing a measurement according to the JIS standard, and for example, a surface roughness measuring device (Surfcorder SE3500, manufactured by Kosaka Corporation) or the like can be used. In addition, measurement conditions are set to A=0.1mm, B=0.5mm, ln=3.2mm, lambda s=2.5 micrometer according to the measurement conditions recommended by the said JIS standard.

In the present invention, the wave number Wn (pieces/mm) is calculated by the following formula (3) based on the roughness motif average length AR measured under the above conditions.

Wn=1/AR … (3)

According to Equation (3) above, the average number of undulations on a line of 1 mm is calculated.

The copper foil of this invention is the bonding surface. WHEREIN: Wn-wave number Wn is 11-30 pieces/mm. By setting it as the said range, a low transmission loss, high adhesiveness, and excellent heat resistance can be implement|achieved. On the other hand, when the wave number Wn is less than 11 pieces/mm, delamination due to the pressure of outgas (low molecular weight resin component gasified by heat) generated from the resin at the resin-resin interface or the resin-copper foil interface. Since propagation cannot be sufficiently suppressed, circuit wiring is easily peeled from the resin substrate, and the yield (heat resistance) is lowered. In addition, when the wave number Wn is more than 30 pieces/mm, a high-frequency signal easily flows through the surface of the copper foil due to the skin effect, the path through which the signal propagates becomes long, and the transmission loss increases. In particular, from the viewpoint of realizing excellent heat resistance and transmission characteristics, the number of undulations Wn is preferably 12 to 27 pieces/mm, more preferably 14 to 22 pieces/mm.

Moreover, the copper foil of this invention WHEREIN: Roughness motif average depth R is 0.20-1.10 micrometers. By controlling the motif average depth R together with the wave number Wn, it is possible to achieve both transmission characteristics and heat resistance at a higher level than before. On the other hand, when the roughness motif average depth R is less than 0.20 µm, the propagation of delamination due to the pressure of outgas generated from the resin at the resin-resin interface or the resin-copper foil interface cannot be sufficiently suppressed. It becomes easy to peel a circuit wiring from a base material, and a yield (heat resistance) falls. In addition, when the roughness motif average depth R is more than 1.10 µm, a high-frequency signal easily flows through the surface of the copper foil due to the skin effect, the path through which the signal propagates becomes long, and the transmission loss increases. In particular, from the viewpoint of realizing excellent heat resistance and transmission characteristics, the roughness motif average depth R is preferably 0.30 to 0.90 µm, more preferably 0.40 to 0.80 µm.

In addition, the wavy number Wn and the roughness motif average depth R should just be controlled within the predetermined range on the bonding surface to be joined with the resin, and the surface properties of other surfaces are appropriate within the range that does not impair the effects of the present invention. can be adjusted

In addition, as for the bonding surface of the copper foil of the present invention, the surface area ratio of the actually measured three-dimensional surface area to the two-dimensional surface area when measured by projecting to a plane is preferably 1.05 to 2.85, and more preferably 2.00 to 2.70. . The surface area ratio of this bonding surface is expressed by the ratio (A/B) of the measured three-dimensional surface area A of the copper foil surface and the two-dimensional surface area B when it is projected and measured on a plane. In addition, the three-dimensional surface area A can be measured, for example with a laser microscope (VK8500, the product made from Keyence Corporation) etc. In addition, the two-dimensional surface area B is an area corresponding to the measurement range of the three-dimensional surface area A at the time of planar view from the copper foil surface side.

In general, it is known that the smaller the surface area ratio is, the shorter the path of the high-frequency signal flowing through the surface layer is due to the skin effect, and the smaller the transmission loss. However, in a heat resistance test, since the contact area between resin - copper foil or resin - resin decreases, there exists a problem that heat resistance falls.

On the other hand, in the copper foil of the present invention, since the surface area ratio is set to 1.05 or more and 2.85 or less by controlling the wavy characteristics of the bonding surface in a predetermined relationship as described above, there is little difference in elevation between the wavy concave and convex portions, and roughening is achieved. The current density in the plating process becomes equal, and roughening particles of the same size are uniformly formed in the concave and convex portions, thereby eliminating non-uniformity in adhesion to the resin and improving heat resistance with low transmission loss. can On the other hand, when the surface area ratio (A/B) is less than 1.05, the contact area between the resin and the copper foil or between the resin and the resin is small, and the heat resistance tends to decrease. Moreover, when the surface area ratio (A/B) is more than 2.85, the path through which a high frequency flows becomes long, and there exists a tendency for a transmission loss to become large.

Moreover, it is preferable that the copper foil of this invention is an electrolytic copper foil. In the case of an electrolytic copper foil, the glossy surface (S surface) is the surface in contact with the electrolytic drum, and the shape of the drum surface becomes a replica, and the uniformity of roughening is easily impaired by the influence of the replica shape. On the other hand, the mat surface (the M surface, also referred to as a roughening surface) is a surface on the electrolytic solution side at the time of electrolysis, and since the irregularities on the drum surface are lost, there is a characteristic that the uniformity of the roughening treatment is excellent. Therefore, in the electrolytic copper foil, it is preferable that the waviness Wn and the roughness motif average depth R are controlled in the said predetermined range especially in the mat surface.

Moreover, it is preferable that the copper foil of this invention is a surface-treated copper foil provided with a surface-treated layer on the surface of a copper foil base|substrate and this copper foil base|substrate by the side of an adhesion|attachment surface. Moreover, it is preferable that the said surface treatment layer contains at least 1 layer of a roughening particle layer, Ni surface treatment layer, Zn surface treatment layer, Cr surface treatment layer, and a silane coupling agent layer, Among them, Ni surface treatment layer and Cr It is more preferable to include at least one of the surface treatment layers, and it is still more preferable to have a multilayer structure comprised by said each layer. Such a surface-treated copper foil WHEREIN: The bonding surface is the surface of the outermost layer of a surface treatment layer.

In addition, since the surface treatment layer is a region with a very thin treatment thickness, it does not affect the undulation number Wn and the roughness motif average depth R in the bonding surface, and the characteristic of the wavy in the bonding surface of the surface-treated copper foil is not affected. Silver is substantially determined by the wavy characteristic in the surface of the copper foil base|substrate corresponding to the said bonding surface. Therefore, the copper foil base of the surface-treated copper foil preferably has a wavy number Wn of 12 to 85 pieces/mm, and an average roughness motif depth R of 0.10 to 1.50 µm on the surface on the bonding surface side. Do. In addition, any of an electrolytic copper foil and a rolled copper foil may be sufficient as such a copper foil base|substrate.

Moreover, since the surface treatment layer contains a roughening particle layer, the adhesiveness of copper foil and a resin base material becomes high by the anchor effect, and even if outgas is generated from a resin base material at the time of heating in a reflow heat resistance test, copper foil and When the adhesiveness of the resin substrate is high, there is an effect of suppressing expansion (delamination), and heat resistance, particularly reflow heat resistance, is improved. It is preferable that a roughening particle layer is formed as a roughening layer on the surface of copper foil base|substrate. Such a roughened particle layer has the advantage of improving adhesiveness and heat resistance as described above. In addition, since there is also a disadvantage that transmission loss increases due to the effect of the skin effect when the size of the roughened particles increases, it is preferable to appropriately adjust the particle size of the roughened particles.

In addition, the surface treatment layer includes a metal treatment layer of at least one of the Ni surface treatment layer, the Zn surface treatment layer, and the Cr surface treatment layer, thereby preventing copper diffusion and providing high adhesion between the copper foil and the resin substrate. can be kept more stable. In the manufacturing process of a printed wiring board, there exist processes accompanying heating, such as a bonding process of resin and copper foil, and a soldering process. The heat added in these steps may cause copper to diffuse to the resin side and reduce the adhesion between the copper foil and the resin. However, by providing a metal treatment layer containing Ni or Cr, diffusion of copper can be effectively prevented. have. In addition, the metal treatment layer as described above also functions as a rust-preventing metal that prevents rust of copper.

The Ni surface treatment layer is a metal treatment layer containing Ni, and in particular, it is preferably formed as a base layer on the surface of the copper foil substrate or on the roughened particle layer. Here, it is preferable that it is 0.010-0.800 mg/dm<2>, and, as for the adhesion amount of Ni, it is more preferable that it is 0.020-0.400 mg/dm<2>. As described above, in the surface of the copper foil substrate on the bonding surface side, the wavy characteristics are controlled within a predetermined range, and the difference in the unevenness of the undulations is suppressed to a certain level or less. It is possible to form a Ni layer having a thickness of one, so that heat resistance is improved compared to the prior art. On the other hand, when the Ni adhesion amount is less than 0.010 mg/dm 2 , since the amount of Ni is small, the copper diffusion preventing effect is small, and the resin tends to deteriorate, so that the heat resistance (resin-copper foil) tends to decrease. Moreover, when Ni adhesion amount is more than 0.800 mg/dm<2>, since Ni has lower electrical conductivity than Cu, there exists a tendency for transmission loss to become large under the influence of a skin effect.

The Cr surface-treated layer is a metal-treated layer containing Cr, and is more preferably formed as a rust-preventive layer on the bonding surface side. Here, it is preferable that it is 0.010-0.300 mg/dm<2>, and, as for the adhesion amount of Cr, it is more preferable that it is 0.015-0.200 mg/dm<2>. As described above, in the surface of the copper foil substrate on the bonding surface side, the wavy characteristics are controlled within a predetermined range, and the difference in the unevenness of the undulations is suppressed to a certain level or less. A Cr layer having one thickness can be formed, and heat resistance is improved compared to the prior art. In addition, by treating Cr on the surface layer, the surface is covered with chromium oxide and chromium hydroxide to obtain an anti-rust effect. On the other hand, when the Cr adhesion amount is less than 0.010 mg/dm 2 , since the Cr amount is small, the copper diffusion preventing effect is small and the resin tends to deteriorate, so that the heat resistance (resin-copper foil) tends to decrease. Moreover, when Cr adhesion amount is more than 0.300 mg/dm<2>, since Cr has lower electrical conductivity than Cu, there exists a tendency for transmission loss to become large under the influence of a skin effect.

The Zn surface treatment layer is a metal treatment layer containing Zn, and is particularly preferably formed as a heat resistant treatment layer between the Ni surface treatment layer and the Cr surface treatment layer. Here, it is preferable that it is 0.005-0.500 mg/dm<2>, and, as for the adhesion amount of Zn, it is more preferable that it is 0.010-0.400 mg/dm<2>. By having such a Zn surface treatment layer, there are advantages such as prevention of discoloration during heating, anti-rust effect, and improvement of heat resistance.

The silane coupling agent layer has an effect of chemically bonding the copper foil and the resin substrate, and is preferably formed as the outermost layer of the surface treatment layer. Here, it is preferable that it is 0.0002-0.0300 mg/dm<2>, and, as for the adhesion amount of a silane, it is more preferable that it is 0.0005-0.0100 mg/dm<2> in conversion of a silicon (Si) atom. By having such a silane coupling agent layer, the adhesiveness of copper foil and a resin base material can further be improved.

In addition, the adhesion amount of the said Ni, Cr, Zn, and a silane can be measured by fluorescence X-ray analysis. Specific measurement conditions are described in Examples to be described later.

The copper foil of this invention can be used suitably as a copper clad laminated board. It is preferable that a copper clad laminated board has the copper foil of this invention, and the insulating board adhesively laminated|stacked on the said bonding surface. Such a copper clad laminated board can produce the circuit board excellent in high heat-resistant adhesiveness and high frequency transmission characteristic, and has the outstanding effect. As an insulating substrate, a flexible resin substrate, a rigid resin substrate, etc. are mentioned, for example. Moreover, the copper clad laminated board of this invention can be used especially suitably as a printed wiring board.

<Manufacturing method of copper foil>

Next, the preferable manufacturing method of the copper foil of this invention is demonstrated.

Hereinafter, an example of the manufacturing method of copper foil is demonstrated taking an electrolytic copper foil (or surface-treated electrolytic copper foil) as an example.

(1) making

The electrolytic copper foil uses an aqueous solution of sulfuric acid-copper sulfate as an electrolyte, and supplies the electrolyte between an insoluble anode containing titanium coated with a platinum group element or an oxide element thereof, and a negative electrode drum made of titanium provided to face the anode, Copper is deposited on the surface of the negative electrode drum by passing a direct current between the anodes while rotating the drum at a constant speed, and the deposited copper is peeled from the surface of the negative electrode drum and continuously wound.

Usually, the wavy number Wn and the roughness motif average depth R depend on the composition of the electrolyte (for example, the concentration of additional components and various components, etc.) and the electrolysis conditions (for example, the current density, liquid temperature, flow rate, etc.) I think. In particular, in a conventional general electrolyte solution, as an additive component of the electrolyte solution other than sulfuric acid and copper sulfate, for example, 3-mercapto-1-propanesulfonate sodium (MPS), hydroxyethyl cellulose (HEC), low molecular weight glue (PBF) , chlorine (added with Cl, eg NaCl) and the like have been used. However, when the present inventors have studied the relationship between the composition of the electrolyte and the wavy phase, when the electrolytic copper foil is manufactured by using the electrolyte containing the additives as described above, as shown in the conventional example A of FIG. 1 , the roughness motif It was found that when the average depth R is reduced, the wave number Wn increases, and the transmission loss characteristic cannot be sufficiently improved.

Therefore, further research was conducted, by adding an additive having the effect of increasing the overvoltage of plating by forming a complex with copper ions such as sodium citrate, sulfamic acid, and aqueous ammonia in addition to the above additives, the roughness motif average depth R In this low state, it was found that the wave number Wn could be reduced (invention of Fig. 1). Although the mechanism by which this phenomenon occurs is not necessarily clear, sodium citrate, sulfamic acid, and aqueous ammonia form a complex with copper ions, thereby increasing the overvoltage of the plating, and as a result, the uniformity of the plating process is increased, and the waviness W can be assumed to have been reduced.

Based on the said knowledge, in this invention, it is preferable to adjust suitably the composition of the electrolyte solution used for foil making. Below, the composition of the electrolyte solution suitable for manufacture of the electrolytic copper foil of this invention, and the example of electrolysis conditions are shown. In addition, the following conditions are a preferable example, The kind, quantity, and electrolysis conditions of an additive can be suitably changed and adjusted as needed within the range which does not impair the effect of this invention.

(Conditions for binding)

Copper sulfate pentahydrate… In conversion of copper (atom), Preferably it is 60-110 g/L, More preferably, it is 60-90 g/L.

sulfuric acid… Preferably 40 to 135 g/L, more preferably 40 to 80 g/L

MPS… Preferably 1 to 10 mg/L, more preferably 2 to 3 mg/L

HEC… Preferably 1 to 7 mg/L, more preferably 1 to 2 mg/L

PBF… Preferably 3 to 9 mg/L, more preferably 3 to 4 mg/L

Sodium citrate… Preferably 0 to 40 g/L, more preferably 20 to 40 g/L

Sulfamic acid… Preferably 0 to 30 g/L, more preferably 10 to 20 g/L

Ammonia water (ammonia concentration 30% by mass)... Preferably 0 to 35 g/L, more preferably 10 to 25 g/L

Chlorine (as Cl, NaCl)... Preferably 15 to 60 mg/L, more preferably 30 to 40 mg/L

Current density… preferably 35 to 60 A/dm 2 , more preferably 40 to 50 A/dm 2

liquid temperature... Preferably 40 to 65°C, more preferably 50 to 60°C

foil thickness... Preferably 6 to 100 μm, more preferably 6 to 65 μm

(2) leveling processing

As a result of earnestly researching a method for appropriately reducing the wave number Wn for the electrolytic copper foil produced as described above, using an electrolytic bath with a strong leveling effect (treatment to reduce the unevenness of the copper foil surface), pulse It has been found that by electrolysis with an electric current, the wave number Wn becomes an appropriate value.

Examples of additional components of the electrolyte solution other than sulfuric acid and copper sulfate used in the electrolytic bath having such a strong leveling effect include low molecular weight glue (PBF), coumarin, 1,4-butynediol, and the like. Moreover, since reflow heat resistance tends to fall when a leveling effect is too strong, it is preferable to adjust suitably in balance with reflow heat resistance.

In addition, with respect to the electrolysis by the pulse current, the _{pulse reverse electrolysis time (t rev} ) is longer than the pulse forward _{electrolysis time (t on} ), and the pulse forward current density (l _on ) is higher than the pulse reverse current density (l _{rev )} It is preferable to set Here, the forward current is a cathode reaction in which the copper foil surface is plated, and the reverse current is an anode reaction in which the copper foil surface is dissolved. By making high the ratio of the reverse current in which the copper foil surface melts in a pulse current, the undulation|corrugation of the corrugation on the surface of copper foil melt|dissolves appropriately, and it is estimated that the copper foil which has an appropriate wave number Wn is obtained.

Based on the said knowledge, in this invention, it is preferable to adjust suitably the composition of the electrolyte solution used for a leveling process, and a pulse current. Below, the composition of the electrolyte solution suitable for the leveling process of this invention, and an example of electrolysis conditions are shown. In addition, the following conditions are a preferable example, The kind, quantity, and electrolysis conditions of an additive can be suitably changed and adjusted as needed within the range which does not impair the effect of this invention.

(Leveling processing conditions)

Copper sulfate pentahydrate… In terms of copper (atomic), preferably 40 to 80 g/L, more preferably 60 to 75 g/L

sulfuric acid… Preferably 60 to 125 g/L, more preferably 100 to 120 g/L

PBF… Preferably 0 to 800 mg/L, more preferably 300 to 500 mg/L

Coumarin... Preferably 0 to 4 g/L, more preferably 2.5 to 3.0 g/L

1,4-butynediol… Preferably 0 to 3 g/L, more preferably 1.0 to 2.0 g/L

Chlorine (as Cl, NaCl)... Preferably 20 to 55 mg/L, more preferably 30 to 40 mg/L

Delivery time... Preferably 3 to 25 seconds, More preferably 5 to 20 seconds

liquid temperature... Preferably 30 to 70°C, more preferably 50 to 60°C

<Pulse condition>

Pulse net electrolysis time (t _on )… preferably 0 to 30 milliseconds,

More preferably 0 to 10 milliseconds

Pulse reversal time (t _rev )… preferably 50 to 600 milliseconds,

More preferably 200 to 300 milliseconds

Pulse electrolysis stop time (t _off )… preferably 0 to 40 milliseconds,

More preferably 20 to 30 milliseconds

Pulse net current density (l _on )… preferably 0 to 10 A/dm 2 ,

More preferably 0 to 6A/dm

Pulse reverse current density (l _rev )… preferably -15 to -50 A/dm 2 ,

More preferably -20 to -30A/dm

(3) surface treatment

In addition, the electrolytic copper foil produced as mentioned above may be used as a copper foil base|substrate, and on the mat surface, surface treatment layers, such as a roughening layer, a base layer, a heat-resistant treatment layer, and a rust prevention treatment layer, as needed, are appropriate. It can also be formed as a surface treatment electrolytic copper foil. In addition, these surface treatment layers do not influence the wavy characteristic in the mat surface of the said electrolytic copper foil, The wavy characteristic in the outermost surface of the surface-treated electrolytic copper foil is the electrolytic copper foil used as a copper foil base|substrate. It is substantially the same as the wavy properties on the mat surface of In addition, a surface treatment layer is not limited to the said processing layer, The part or all may be combined suitably, and may be combined with processing layers other than the above.

Here, although a roughening layer can be formed by a well-known method, it is preferable to perform by electroplating, for example, and it is more preferable to perform by two-step roughening plating process. Such a roughening plating process can be suitably adjusted and performed by a well-known method.

Hereinafter, the composition of the plating liquid for roughening plating processes, and the example of electrolysis conditions are shown. In addition, the following conditions are a preferable example, The kind, quantity, and electrolysis conditions of an additive can be suitably changed and adjusted as needed within the range which does not impair the effect of this invention.

(Conditions for roughening plating treatment (1))

Copper sulfate pentahydrate… In terms of copper (atomic), preferably 5 to 30 g/L, more preferably 10 to 20 g/L

sulfuric acid… Preferably 100 to 150 g/L, more preferably 130 to 140 g/L

Ammonium molybdate… In terms of molybdenum (atom), preferably 1 to 6 g/L, more preferably 2 to 4 g/L

Cobalt sulfate heptahydrate… In terms of cobalt (atom), preferably 1 to 5 g/L, more preferably 2 to 3 g/L

Iron (II) sulfate heptahydrate... In terms of iron (atom), preferably 0.05 to 5.0 g/L, more preferably 0.1 to 1.5 g/L

Current density… preferably 15 to 50 A/dm 2 , more preferably 20 to 40 A/dm 2

Delivery time... Preferably 1 to 80 seconds, More preferably 1 to 60 seconds

liquid temperature... Preferably 20 to 50 °C, more preferably 30 to 40 °C

(Conditions for roughening plating treatment (2))

Copper sulfate pentahydrate… In terms of copper (atomic), preferably 10-80 g/L, more preferably 13-72 g/L

sulfuric acid… Preferably 20 to 150 g/L, more preferably 26 to 133 g/L

Current density… preferably 2 to 70 A/dm 2 , more preferably 3 to 67 A/dm 2

Delivery time... Preferably 1 to 80 seconds, More preferably 1 to 60 seconds

liquid temperature... Preferably 15 to 75°C, more preferably 18 to 67°C

Further, the underlayer includes, for example, a Ni surface treatment layer containing Ni formed by Ni plating treatment, an underlayer formed by Cu-Zn alloy plating, Cu-Ni alloy plating treatment, and the like. have. These plating processes can be suitably adjusted and performed by a well-known method.

Hereinafter, the composition of the plating liquid for Ni plating processes and the example of electrolysis conditions are shown. In addition, the following conditions are a preferable example, The kind, quantity, and electrolysis conditions of an additive can be suitably changed and adjusted as needed within the range which does not impair the effect of this invention.

(Conditions for Ni plating)

Nickel sulfate… In terms of nickel (atomic), preferably 3.0 to 7.0 g/L, more preferably 4.0 to 6.0 g/L

Ammonium persulfate… Preferably 30.0 to 50.0 g/L, More preferably 35.0 to 45.0 g/L

Boric acid… Preferably 20.0-35.0g/L, More preferably, 25.0-30.0g/L

Current density… preferably 0.5 to 4.0 A/dm 2 , more preferably 1.0 to 2.5 A/dm 2

Delivery time... Preferably 1 to 80 seconds, More preferably 1 to 60 seconds

Liquid pH… Preferably 3.5 to 4.0, more preferably 3.7 to 3.9

liquid temperature... Preferably 25 to 35 °C, more preferably 26 to 30 °C

As a heat-resistant process layer, the heat-resistant process layer etc. which were formed with the Zn surface-treated layer containing Zn formed by Zn plating process, for example are mentioned. These plating processes can be suitably adjusted and performed by a well-known method.

Hereinafter, examples of the composition and electrolysis conditions of the plating solution for Zn plating are shown. In addition, the following conditions are a preferable example, The kind, quantity, and electrolysis conditions of an additive can be suitably changed and adjusted as needed within the range which does not impair the effect of this invention.

(Conditions for Zn plating)

Zinc sulfate heptahydrate… In terms of zinc (atomic), preferably 1 to 40 g/L, more preferably 1 to 30 g/L

Sodium hydroxide… Preferably 8 to 350 g/L, more preferably 10 to 300 g/L

Current density… Preferably 0.1 to 15 A/dm 2 , more preferably 0.1 to 10 A/dm 2

Delivery time... Preferably 1 to 80 seconds, More preferably 1 to 60 seconds

liquid temperature... Preferably 5 to 80 °C, more preferably 5 to 60 °C

As a rust preventive treatment layer, the Cr surface treatment layer (inorganic rust preventive layer) containing Cr formed by Cr plating treatment, for example, an organic rust preventive layer formed by organic rust preventive treatment, such as a benzotriazole treatment, a silane coupling agent, for example. The rust prevention layer etc. which were formed by the process are mentioned. These plating processes can be suitably adjusted and performed by a well-known method.

Cr plating treatment is performed _{by dissolving CrO 3} or K ₂ Cr ₂ O ₇ in water to make an aqueous solution, immersing copper foil in the aqueous solution, washing with water, drying, or using copper foil as a cathode in aqueous solution to conduct electrolysis After carrying out, a process is performed by washing with water and drying.

Hereinafter, the composition of the plating for Cr plating process and the example of electrolysis conditions are shown. In addition, the following conditions are a preferable example, The kind, quantity, and electrolysis conditions of an additive can be suitably changed and adjusted as needed within the range which does not impair the effect of this invention.

(Conditions for Cr plating)

chromic anhydride (CrO ₃ )… In terms of chromium (atomic), preferably 0.5 to 1.5 g/L, more preferably 0.8 to 1.1 g/L

Current density… Preferably 0.3 to 0.6 A/dm 2, more preferably 0.4 to 0.6 A/dm 2

Delivery time... Preferably 1 to 80 seconds, More preferably 1 to 60 seconds

Liquid pH… Preferably 2.2 to 2.8, more preferably 2.3 to 2.6

liquid temperature... Preferably 15 to 50 °C, more preferably 20 to 40 °C

The benzotriazole treatment is performed by dissolving benzotriazole or a benzotriazole derivative in an organic solvent or water and immersing copper foil in the solution, followed by drying.

In addition, after melt|dissolving a silane coupling agent in an organic solvent or water, copper foil is immersed in the solution, or a silane coupling agent process apply|coats on copper foil, a process is performed by drying. Examples of the silane coupling agent used herein include vinylsilane, epoxysilane, styrylsilane, methacrylsilane, acrylsilane, aminosilane, ureasilane, mercaptosilane, sulfidesilane, and isocyanatesilane.

In addition, you may perform the said chromate process, a benzotriazole process, and a silane coupling agent process combining suitably.

As mentioned above, although embodiment of this invention was described, the said embodiment is only an example of this invention. The present invention includes all aspects included in the concept and claims of the present invention, and various modifications can be made within the scope of the present invention. For example, although the manufacturing method of an electrolytic copper foil was demonstrated in detail in the above, the method of manufacturing the copper foil of this invention is not limited to the said method. That is, if the characteristic of the bonding surface of copper foil is controlled in the appropriate range of this invention, a rolled copper foil (or surface-treated rolled copper foil) may be sufficient, and the copper foil produced by other manufacturing methods may be sufficient.

<Example>

Hereinafter, although this invention is demonstrated in more detail based on an Example, the following is an example of this invention.

(Examples 1 to 24 and Comparative Examples 1 to 20)

[1] Seduction

First, the electrolytic copper foil was made into the composition and electrolysis conditions of the electrolytic solution shown in Table 1. At this time, about Examples 1-21 and Comparative Examples 19 and 20, foil thickness was adjusted in advance so that the thickness of copper foil might be set to 18 micrometers after the leveling process performed next, and it made into foil. In addition, about Comparative Examples 1-18, since the leveling process was not performed, at this time, it made foil so that foil thickness might be set to 18 micrometers. Further, Example 24 is a copper foil, containing oxygen-free rolled copper A, having a thickness of 17.8 µm, a surface roughness Rz specified in JIS-B-0601 of 0.7 µm, and tensile at a temperature of 25 degrees The rolled copper foil whose elongation rate at the time of testing was used was 6.0 %.

In Table 1, "Cu" represents copper sulfate pentahydrate in terms of Cu atom, "MPS" represents sodium 3-mercapto-1-propanesulfonate, "HEC" represents hydroxyethyl cellulose, and "PBF" is a low molecular weight glue, "ammonia water" is ammonia water with a concentration of 30% by mass, "Cl" is a chlorine component added as sodium chloride, "SPS" is sodium 4-styrenesulfonate, "DDAC" is diallyldimethylammonium chloride Polymers are respectively meant (the same applies in Tables 2 and 3 below).

[2] Leveling processing

In Examples 1-21 and Comparative Examples 19 and 20, the electrolytic copper foil after [1] and the rolled copper foil of Example 24 were further subjected to a leveling treatment under the composition and electrolysis conditions of the electrolyte shown in Table 2, A leveling layer was formed. The foil thickness of the copper foil after leveling layer formation was 18 micrometers.

[3] Formation of a roughening layer (roughening particle layer)

ㆍRoughening plating treatment (1)

The copper foil obtained in said [1] and [2] was used as a base|substrate, and the roughening plating process was performed on the mat surface. At this time, the composition and electrolysis conditions of the plating liquid were made into the conditions shown in Table 3. In addition, in Example 21 and Comparative Example 13, the roughening plating process (1) was not implemented.

In Table 3, "Mo" is ammonium molybdate added in terms of Mo atoms, "Co" is cobalt sulfate heptahydrate injected in terms of Co atoms, and "Fe" is iron sulfate added in terms of Fe atoms ( II) each means heptahydrate.

ㆍRoughening plating treatment (2)

Then, the roughening plating process (2) was further performed with respect to the surface (mat surface) of the copper foil base|substrate after the said roughening plating process (1). At this time, the composition and electrolysis conditions of the plating liquid are as follows. In addition, in Example 21 and Comparative Example 13, the roughening plating process (1) was not implemented.

<Roughening plating (2) conditions>

Copper sulfate pentahydrate… … … … In terms of copper (atomic), 65.0 g/L

sulfuric acid… … … … 108g/L

liquid temperature... … … … 56℃

Current density… … … … 4A/d㎡

Delivery time... … … … 1 to 20 seconds

[4] Formation of an underlayer containing Ni (Ni surface treatment layer)

Next, on the said roughening layer, the base layer used as the foundation|substrate of a heat-resistant process layer was formed by electroplating. At this time, Ni plating conditions are as follows. In addition, in Example 12 and Example 20, the Ni process was not implemented.

<Ni plating conditions>

Nickel sulfate… … … … In terms of nickel (atomic), 5.0 g/L

Ammonium persulfate… … … … 40.0 g/L

Boric acid… … … … 28.5g/L

liquid temperature... … … … 28.5℃

Liquid pH… … … … 3.8

Current density… … … … 1.5A/d㎡

Delivery time... … … … 1 to 20 seconds

[5] Formation of a heat-resistant treatment layer containing Zn (Zn surface treatment layer)

Then, a heat-resistant treatment layer (amount of Zn adhesion: 0.05 mg/dm 2 ) was formed on the underlayer by electrolytic plating. At this time, the Zn plating conditions are as follows. In addition, in Example 20, Zn treatment was not performed.

<Zn plating conditions>

Zinc sulfate heptahydrate… … … … In terms of zinc (atomic), 10 g/L

Sodium hydroxide… … … … 50g/L

liquid temperature... … … … 32℃

Current density… … … … 5.0A/d㎡

Delivery time... … … … 1 to 20 seconds

[6] Formation of an anti-rust treatment layer containing Cr (Cr surface treatment layer)

Moreover, on the said heat-resistant process layer, the antirust process layer was formed by electroplating. At this time, Cr plating conditions are as follows. In addition, in Examples 16 and 20, Cr treatment was not implemented.

<Cr plating conditions>

chromic anhydride (CrO ₃ )… … … … In terms of chromium (atomic), 0.9 g/L

liquid temperature... … … … 32.0℃

Liquid pH… … … … 2.5

Current density… … … … 0.5A/d㎡

Delivery time... … … … 1 to 20 seconds

[7] Formation of silane coupling agent layer

Finally, on the rust-preventive treatment layer, an aqueous solution of 3-methacryloxypropyltrimethoxysilane having a concentration of 0.7% by mass is applied, dried, and a silane coupling agent layer (the amount of silane adhered in terms of Si atoms is 0.0070 mg/ dm2) was formed.

(evaluation)

About the copper foil which concerns on the said Example and a comparative example, the measurement and evaluation shown below were performed. Each evaluation condition is as follows. A result is shown in Table 4.

In addition, the following measurement WHEREIN: The bonding surface of copper foil is the surface (the outermost surface of the mat surface side of the electrolytic copper foil which is base|substrate) of the silane coupling agent layer which is the outermost layer of copper foil. In Table 4, the surface treatment layer (i) includes a roughened particle layer, a Ni surface treatment layer, a Zn surface treatment layer, a Cr surface treatment layer, and a silane coupling agent layer, the surface treatment layer (ii) is Ni A surface-treated layer (iii) comprising a surface-treated layer, a Zn surface-treated layer, a Cr surface-treated layer and a silane coupling agent layer, the surface-treated layer (iii) comprises a roughened particle layer, a Zn surface-treated layer, a Cr surface-treated layer, and a silane coupling agent layer. The surface-treated layer (iv) includes a roughened particle layer, a Ni surface-treated layer, a Zn surface-treated layer, and a silane coupling agent layer, and the surface-treated layer (v) includes a roughened particle layer and a silane coupling agent layer. It is meant to include a layered layer, respectively.

[1] Wave number Wn

About the bonding surface of copper foil, roughness motif average length AR (mm) was measured according to the prescription|regulation of JISB0631:2000. The measurement was performed at arbitrary five places about each copper foil, and the average value (N=5) was made into roughness motif average length AR of each copper foil. In addition, as a measuring device, a surface roughness measuring device (Surfcorder SE3500, manufactured by Kosaka Genkyusho Co., Ltd.) was used, and measurement conditions were A = 0.1 mm, B = 0.5 mm, ln = 3.2 mm, λs = 2.5 μm, The measurement range was made into the range of 50 mm in length in the TD direction (direction perpendicular|vertical with respect to the long side direction (corresponding to the film forming direction) of copper foil). From the measured roughness motif average length AR, the average number of undulations (1/AR) on a line of 1 mm was calculated as the number of undulations Wn (pieces/mm).

[2] Roughness motif average depth R

About the adhesive surface of copper foil, according to the prescription|regulation of JISB0631:2000, roughness motif average depth R (micrometer) was measured. The measurement was performed at arbitrary five places with respect to each copper foil, and the average value (N=5) was made into the roughness motif average depth R of each copper foil. In addition, as a measuring device, a surface roughness measuring device (Surfcorder SE3500, manufactured by Kosaka Genkyusho Co., Ltd.) was used, and measurement conditions were A = 0.1 mm, B = 0.5 mm, ln = 3.2 mm, λs = 2.5 μm, The measurement range was performed in the range of 50 mm in length in the TD direction (direction perpendicular|vertical with respect to the long side direction (corresponding to the film forming direction) of copper foil).

[3] Contact roughness Rz, Ra

About the bonding surface of copper foil, according to the prescription|regulation of JISB0601:1994, 10-point average roughness Rz (micrometer) and arithmetic mean roughness Ra (micrometer) were measured. The measurement was performed at arbitrary five places about each copper foil, and the average value (N=5) was made into 10-point average roughness Rz and arithmetic mean roughness Ra of each copper foil, respectively. In addition, as a measuring apparatus, the contact-type surface roughness meter (SE1700, the Kosaka Genkyusho Co., Ltd. make) was used. The measurement conditions were made into a measurement length of 4.8 mm, sampling length of 4.8 mm, and a cut-off value of 0.8 mm.

[4] Non-contact roughness Rz, Ra

As in the case of the above [3] contact-type roughness, except that a non-contact laser microscope (VK8500, manufactured by Keyence, Ltd.) was used as the measuring device, the 10-point average roughness Rz (μm) on the adhesive surface of the copper foil and The arithmetic mean roughness Ra (μm) was measured.

[5] Surface area ratio A/B

The adhesion surface of copper foil WHEREIN: The three-dimensional surface area (micrometer ² ) was measured using the laser microscope (VK8500, the product made by Keyence Corporation). The measurement was performed at five arbitrary places about each copper foil, and the average value (N=5) was made into the three-dimensional surface area of each copper foil. In addition, the measurement field was made into the range of 30.0 micrometers x 44.9 micrometers, and this was made into the two-dimensional area corresponding to the three-dimensional surface area. From the measured three-dimensional surface area A and the corresponding secondary area B, a surface area ratio (three-dimensional surface area A/2-dimensional surface area B) was calculated.

[6] Ni, Zn, Cr and silane adhesion amount

The adhesion amounts of Ni, Zn, Cr and silane were measured. The measurement was analyzed using a fluorescence X-ray analyzer (ZSXPrimus, manufactured by Rigaku Co., Ltd.) at an analysis diameter: phi 35 mm. In addition, the adhesion amount of Zn and silane is as above-mentioned.

[7] Transmission loss

A resin substrate was bonded to the bonding surface of the copper foil to prepare a substrate sample for measurement of transmission characteristics. As the resin substrate, a commercially available polyphenylene ether-based resin (ultra-low transmission loss multilayer substrate material MEGTRON6, manufactured by Panasonic Corporation) was used, and the curing temperature at the time of bonding was 210° C., and the curing time was 2 hours. The substrate for transmission loss measurement had a strip-line structure, and was adjusted to have a conductor length of 400 mm, a conductor thickness of 18 µm, a conductor width of 0.14 mm, a total thickness of 0.31 mm, and a characteristic impedance of 50 Ω. For the measurement samples adjusted as described above, transmission losses at 10 GHz and 40 GHz were measured using a vector network analyzer E8363B (KEYSIGHT TECHNOLOGIES). In the evaluation result, the unit is dB/m, and the transmission loss measured at a conductor length of 400 mm is converted into a transmission loss value per 1000 mm of conductor length (the value of the transmission loss measured at a conductor length of 400 mm is multiplied by 2.5). expressed as a value. In this embodiment, a pass level of 19.5 dB/m or less of transmission loss at 10 GHz was set as a pass level, and a transmission loss of 66.0 dB/m or less at 40 GHz was set as the pass level.

[8] Reflow heat resistance

In FIG. 2, the schematic of the manufacturing procedure of the test piece T2 of a reflow heat resistance test is shown. First, as shown in Fig. 2(a), a commercially available polyphenylene ether-based resin (ultra-low transmission loss multilayer substrate material MEGTRON6, manufactured by Panasonic Corporation) is prepared as the first resin substrate (B1), B1 Each copper foil (M1) according to the present Example or Comparative Example was laminated and adhered on both surfaces of the to prepare a copper-clad laminate (P). Then, as shown in FIG.2(b), the copper clad laminated board P was etched with the copper(II) chloride solution, and all the copper foil parts M1 were melt|dissolved. Thereafter, a second resin substrate (B2) is laminated and adhered to both surfaces of the etched first resin substrate (resin core layer) (B1) (FIG. 2(c)), and further, the second resin substrate on both surfaces ( A test piece (T2) (100 mm × 100 mm) for measuring reflow heat resistance was prepared by laminating and adhering each copper foil (M2) according to the present Example or Comparative Example on the prepreg layer) (B2) (Fig. 2(d)). Five test pieces were produced with respect to each copper foil. Next, the produced test piece (T2) is passed through a reflow furnace with a top temperature of 260°C and a heating time of 10 seconds, between each layer of copper foil-resin (M2-B2) or resin-resin (B2-B1). , it was visually observed whether swelling (delamination) occurred. Thereafter, the test piece (T2) in which delamination was observed on both the copper foil-resin and the resin-resin was removed, and the other test piece (T2) was passed through the reflow furnace under the heating conditions again, and the copper foil- The passage through the reflow and observation of delamination were repeated until swelling was observed in both layers of the resin and the resin-resin. And with respect to each interlayer of copper foil-resin and resin-resin, the number of passages by reflow when delamination generate|occur|produced was measured. This measurement was implemented with 5 test pieces about each copper foil, and evaluated the average value (N=5) of the number of passages by each reflow as the reflow heat resistance of each copper foil. Here, the reflow heat resistance between the copper foil and the resin represents the heat resistance of the joint between the copper foil and the prepreg layer, and the reflow heat resistance between the resin and the resin represents the heat resistance of the joint between the core layer and the prepreg layer, respectively. It has shown that it is excellent in heat resistance, so that there are many times of passage through a furnace. In this Example, about each interlayer of copper foil-resin and resin-resin, the thing which passed 8 times or more by reflow until delamination was observed was made into the pass level.

[9] Adhesion strength (peel strength)

The resin base material was bonded to the adhesive surface of copper foil, and the sample for a measurement was produced. As the resin substrate, a commercially available polyphenylene ether-based resin (ultra-low transmission loss multilayer substrate material MEGTRON6, manufactured by Panasonic Corporation) was used, and the curing temperature at the time of bonding was 210° C., and the curing time was 1 hour. The prepared measurement sample was subjected to etching processing with a circuit wiring of 10 mm width, the resin side was fixed to a stainless plate with a double-sided tape, and the circuit wiring was peeled off at a speed of 50 mm/min in a 90 degree direction, an index of adhesion strength The peel strength (kN/m) was measured as The measurement was performed using a universal material testing machine (Tensilon, manufactured by A&D Corporation). In this Example, peeling strength (initial stage adhesiveness) made 0.4 kN/m or more the pass level.

As shown in Table 4, the copper foils according to Examples 1 to 24 had a wavy number Wn of 11 to 30 pieces/mm, and an average roughness motif depth R of 0.20 to 1.10 µm on the bonding surface with the resin substrate. It was confirmed that it has low transmission loss, excellent reflow heat resistance, and exhibits high adhesion strength.

On the other hand, in the copper foils according to Comparative Examples 1 to 20, in the bonding surface with the resin substrate, the undulation Wn is not controlled to 11 to 30 pieces/mm, or the roughness motif average depth R is controlled to 0.20 to 1.10 µm It was not made, or since it was both, it was confirmed compared with the copper foil which concerns on Examples 1-24 that any one or more of a transmission loss, reflow heat resistance, and adhesive strength was inferior.

Claims (13)

When the characteristic of the bonding surface of copper foil is expressed by the undulation number Wn calculated from the roughness motif determined by the motif method prescribed in JIS B0631:2000 and the roughness motif average depth R, the wavy number Wn is 11 to 30 pieces/mm , Further, the roughness motif average depth R is 0.20 to 1.10 μm, Copper foil characterized in that. According to claim 1,
The said wavy number Wn is 12-27 pieces/mm, and the said roughness motif average depth R is 0.30-0.90 micrometers, Copper foil. 3. The method of claim 2,
The said wavy number Wn is 14-22 pieces/mm, and the said roughness motif average depth R is 0.40-0.80 micrometers, Copper foil. 4. The method according to any one of claims 1 to 3,
The said bonding surface is a copper foil whose surface area ratio with respect to the two-dimensional surface area when projected and measured on the plane of the three-dimensional surface area of an actual measurement is 1.05-2.85. 5. The method of claim 4,
The said bonding surface is a copper foil whose surface area ratio with respect to the two-dimensional surface area when projected and measured on the plane of the three-dimensional surface area actually measured is 2.00-2.70. 4. The method according to any one of claims 1 to 3,
The copper foil whose said copper foil is an electrolytic copper foil. 4. The method according to any one of claims 1 to 3,
Copper foil, wherein the bonding surface is a matte surface. 4. The method according to any one of claims 1 to 3,
The said copper foil is a copper foil base|substrate and the surface-treated copper foil provided with a surface treatment layer on the surface of the said copper foil base|substrate on the said bonding surface side,
The surface treatment layer includes at least one of a roughened particle layer, a Ni surface treatment layer, a Zn surface treatment layer, a Cr surface treatment layer, and a silane coupling agent layer,
The said adhesive surface is copper foil whose outermost surface of the said surface treatment layer. 9. The method of claim 8,
The surface treatment layer includes the Ni surface treatment layer,
Copper foil whose adhesion amount of Ni is 0.010-0.800 mg/dm<2>. 10. The method of claim 9,
The adhesion amount of the Ni is 0.020 to 0.400 mg/dm 2 , copper foil. 9. The method of claim 8,
The surface treatment layer includes the Cr surface treatment layer,
Copper foil whose adhesion amount of Cr is 0.010-0.300 mg/dm<2>. 12. The method of claim 11,
The adhesion amount of the Cr is 0.015 to 0.200 mg/dm 2 , copper foil. The copper clad laminated board which has the copper foil as described in any one of Claims 1-3, and the insulating board adhesively laminated|stacked on the said bonding surface.

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