TW202001000A - Surface-treated copper foil, copper-cladded laminate plate, and printed wiring board - Google Patents

Abstract

Provided is a surface-treated copper foil which has such fine wiring pattern processability that a fine wring pattern having an L & S value of 30/30 [mu]m or less, for example, can be formed by a subtractive process having excellent process cost, and which has excellent close adhesiveness to a resin-made substrate. A surface-treated copper foil having, formed on a surface thereof, a roughened surface roughened by a roughening treatment, wherein the foil thickness is 10 [mu]m or less and the vertex curvature arithmetic average Ssc of the roughened surface is 0.7 to 3.8 [mu]m<SP>-1</SP> inclusive. When a cross section is analyzed by an electron backscatter diffraction method after heating at 200 DEG C for two hours, the ratio R1 of the number of crystal grains each having a crystal grain diameter of 0.5 [mu]m or more and less than 1.0 [mu]m is 0.51 to 0.97 inclusive, the ratio R2 of the number of crystal grains each having a crystal grain diameter of 1.0 [mu]m or more and less than 3.0 [mu]m is 0.03 to 0.42 inclusive and the ratio R3 of the number of crystal grains each having a crystal grain diameter of 3.0 [mu]m or more is 0.07 or less in crystal grains each having a crystal grain diameter of 0.5 [mu]m or more.

Description

Surface-treated copper foil, copper-clad laminate and printed circuit board

The present invention relates to a surface-treated copper foil, a copper-clad laminate and a printed wiring board using the surface-treated copper foil. The surface-treated copper foil is suitable for the fineness of printed wiring boards with high-density wiring circuits (fine patterns), etc. Wiring processability and adhesion to resin substrates are excellent.

As the copper foil used for the copper clad laminate and the printed wiring board, an electrolytic copper foil obtained by peeling the copper foil deposited on the drum of the electrolysis device from the drum is used. The electrolysis copper foil obtained by peeling off the drum has a relatively smooth starting surface (smooth surface. Hereinafter, referred to as "S surface"), and an end surface (rough surface. "M plane") usually has irregularities. A resin substrate is arranged on the M surface of the electrolytic copper foil and is subjected to thermocompression bonding to produce a copper-clad laminate. The M surface is roughened by roughening to improve the adhesion to the resin substrate.

Recently, the industry has previously bonded an adhesive resin such as epoxy resin on the roughened surface of the copper foil to make the adhesive resin semi-cured (stage B) insulating resin layer to make a copper foil with resin The copper foil with resin is used as a copper foil for surface circuit formation, and the side of the insulating resin layer of the copper foil is thermocompression-bonded to an insulating substrate, thereby manufacturing a printed wiring board (especially a build-up wiring board). For multi-layer circuit boards, it is desired to integrate various electronic components highly. Corresponding to this, wiring patterns are also required to be denser, and thus gradually become wiring patterns requiring fine line widths and spacing between lines, so-called fine Patterned printed circuit board. For example, as a multilayer substrate used in servers, routers, communication base stations, automotive substrates, etc., or a multilayer substrate for smartphones, a printed circuit board with high-density and extremely fine wiring is required (hereinafter, referred to as "high-density circuit board" ).

Any-layer (AnyLayer) high-density circuit boards (connected between layers using laser vias with a high degree of freedom in configuration) are mainly used for smart phone motherboards, but in recent years, fine wiring has been continuously promoted, requiring line width and line-to-line The wiring distance between them (hereinafter referred to as "L&S") is 30 µm or less. High-density circuit boards were previously manufactured by printed circuit board manufacturers using the photoresist subtraction method, but if the L&S becomes narrower, the cross-sectional shape of the wiring collapses, so the high-density circuit is made with a large area such as more than 500 mm square When the board is packaged and molded, it is difficult to form wiring with an L&S of 30 µm/30 µm (line width (L) of 30 µm and distance between lines (S) of 30 µm).

Therefore, recently, in order to form wiring with L&S of 30 µm/30 µm or less in high-density wiring boards, the introduction of the MSAP method (Modified Semi Additive Process) has been continuously promoted. However, the MSAP method has a higher process cost than the subtractive method, so there is a problem of a large burden on the circuit board manufacturer. In addition, when forming fine wiring, it is effective to reduce the surface roughness of the copper foil. On the other hand, if the surface roughness of the copper foil is reduced, the adhesion between the resin substrate and the copper foil may be reduced.

Patent Literature 1 discloses a technique for forming fine wiring by miniaturizing the average crystal grain size of the entire ultra-thin copper layer, but if the crystal grain size is too small, there may be side corrosion (lateral etching of the wiring cross section). Therefore, it is impossible to obtain a high etching factor. In addition, Patent Document 2 discloses a copper foil having excellent adhesion to a high heat-resistant resin, but coarse particles with sharp shapes are easily dissolved and left during etching (residual roots), and the workability of fine wiring becomes insufficient Yu.

[Prior Technical Literature] (Patent Literature) Patent Document 1: Japanese Patent No. 6158573 Patent Document 2: Japanese Patent Laid-Open No. 2010-236058

[Problems to be solved by the invention] The problem of the present invention is to provide a surface-treated copper foil having a fine wiring processability that can form fine wiring with L&S of, for example, 30 µm/30 µm or less by a reduction method excellent in process cost, and has adhesion to a resin substrate Excellent. In addition, the problem of the present invention is to provide a copper-clad laminate having fine wiring processability as described above, and a printed wiring board having high-density extremely fine wiring.

[Technical Means for Solving the Problems] The main purpose of the surface-treated copper foil of one aspect of the present invention is that it is a surface-treated copper foil with a roughened surface formed by roughening treatment on the surface, and the foil thickness is 10 μm or less, The arithmetic mean Ssc of the vertex curvature of the roughened surface is 0.7 µm ^-1 or more and 3.8 µm ^-1 or less. After heating at 200°C for 2 hours, the crystal grain size is 0.5 µm when the profile is analyzed by the electron beam backscatter diffraction method Among the above crystal grains, the ratio R1 of the number of crystal grains having a crystal grain diameter of 0.5 µm or more and less than 1.0 µm is 0.51 or more and 0.97 or less, and those having a crystal grain diameter of 1.0 µm or more and less than 3.0 µm The ratio R2 of the number is 0.03 or more and 0.42 or less, and the ratio R3 of the number of crystal particles having a crystal grain size of 3.0 µm or more is 0.07 or less.

In addition, the main aspect of the copper-clad laminate according to another aspect of the present invention is: a resin substrate provided with the surface-treated copper foil of the above aspect, and a roughened surface laminated on the surface-treated copper foil. Furthermore, the main purpose of the printed wiring board of another aspect of the present invention is to include the above-mentioned copper clad laminate of another aspect.

[Effect of invention] The surface-treated copper foil of the present invention has fine wiring processability for forming fine wirings with L&S of, for example, 30 µm/30 µm or less by a reduction method excellent in process cost, and has excellent adhesion to a resin substrate. In addition, the copper-clad laminate of the present invention has the fine wiring processability as described above. Furthermore, the printed wiring board of the present invention has high-density extremely fine wiring.

An embodiment of the present invention will be described. In addition, the embodiment described below shows an example of the present invention, and the present invention is not limited to this embodiment. In addition, various changes or improvements can be added to the present embodiment, and such changes or improvements can also be included in the present invention.

The inventors of the present invention conducted intensive studies, and as a result, it was found that the fine wiring processability of copper foil has a high influence on the distribution state of crystal grains having a crystal grain diameter of 0.5 µm or more in the copper foil. In general, it is known that in the etching process of fine wiring, it is preferentially dissolved in the grain boundaries of the crystal grains compared to the crystal grains. The crystal grain boundary is equivalent to the boundary of crystal grains with different plane orientations. There are many mismatches and defects in the arrangement of atoms, so it is in an energy-active state, so it is easily dissolved in etching. Therefore, it can be considered that the finer the crystal grains in the copper foil, the more the crystal grain boundaries increase, and the faster the dissolution rate.

The factors affecting the improvement of the processability of the fine wiring of the copper foil were investigated, and as a result, it was found that when heated at 200°C for 2 hours, the crystal grains with a crystal grain diameter of 0.5 µm or more and less than 1.0 µm were in a fixed ratio, and the longitudinal dissolution during etching The speed increases and the etching factor increases. However, on the other hand, it was found that if the ratio of crystal grains of this size is too large, on the contrary, the lateral dissolution of the top side of the wiring pattern cross section (hereinafter, the upper part of the pattern is the top and the lower part of the pattern is the bottom) is preferentially performed, The etch factor is reduced.

Specifically, when the profile is analyzed by electron beam backscatter diffraction after heating at 200°C for 2 hours, among crystal grains with a crystal grain size of 0.5 µm or more, if the crystal grain size is 0.5 µm or more and less than 1.0 The ratio R1 of the number of crystal grains of µm is 0.51 or more and 0.97 or less, the etching factor increases. However, if the ratio R1 is greater than 0.97, the etching on the top side is preferentially performed and the fine wiring processability is reduced. If the ratio R1 is less than 0.51, the etching speed in the thickness direction of the copper foil is slowed and the fine wiring process is reduced.

In addition, if the crystal grain size is 3.0 µm or more, the area of the grain boundary is small relative to the volume of the crystal grains, and it is easy to dissolve and remain. Therefore, the wiring pattern is likely to be trailed due to the decrease in the etching rate. Specifically, when the profile is analyzed by electron beam backscatter diffraction after heating at 200°C for 2 hours, one of the crystal grains having a crystal grain size of 0.5 µm or more has a crystal grain size of 3.0 µm or more. When the ratio R3 of the number is 0 or more than 0 and within the range of 0.07 or less, the fine wiring processability is improved. However, if the ratio R3 is greater than 0.07, the influence of the dissolving residue of large-sized crystal grains increases and the fine wiring processability decreases.

The details will be described later. The distribution of the crystal grains as described above can be controlled by making the current density given to the electrolyte uniform during the manufacture of the electrolytic copper foil. Furthermore, in the course of investigating factors contributing to the processability of fine wiring, it was found that the arithmetic average of the curvature of the portion near the ridge of the roughened particles of the copper foil (the arithmetic average of the apex curvature of the roughened surface) Ssc has a strong influence. Specifically, when the arithmetic mean Ssc of vertex curvature is 0.7 µm ^-1 or more and 3.8 µm ^-1 or less, the etching factor increases. The vertex curvature arithmetic mean Ssc is the average peak curvature of various mountain structures and is expressed by the following formula. In the following formula, z(x, y) is the coordinate in the height direction of the x and y coordinates, and N is the number of vertices of the coarsened particles.

[Formula 1]

When the arithmetic mean Ssc of the apex curvatures exists within this range, the curvature of the apex of the roughened particles on the roughened surface of the copper foil is in a moderate state, so it is considered that no root residues will occur during etching (the top of the roughened particles will dissolve and remain) Condition) and easy to dissolve, the tailing of the copper foil is suppressed and the etching factor increases.

When the arithmetic mean Ssc of the apex curvature is greater than 3.8 µm ^-1 , the apex of the roughened particles is strongly bent, so the roughened particles penetrate deeply into the resin substrate, causing root residues during etching, and copper foil tailing It becomes longer and the etching factor decreases. When the arithmetic mean Ssc of the vertex curvature is less than 0.7 µm ^-1 , the vertices of the roughened particles have a gentle curvature, so the roughened particles have poor penetration into the resin substrate (weak anchor effect), and the adhesion between the resin substrate and the copper foil reduce.

The details will be described later. The vertex curvature arithmetic mean Ssc can be reduced by dissolving the vertices of the coarsened particles. Therefore, if the copper foil is immersed in an aqueous solution of copper sulfate after pulse plating and roughening Method to dissolve the vertex of the coarsened particles, the vertex curvature arithmetic mean Ssc can be controlled.

That is, the surface-treated copper foil of one embodiment of the present invention is a surface-treated copper foil having a roughened surface formed by roughening on the surface, and the foil thickness is 10 µm or less, and the arithmetic mean of the vertex curvature of the roughened surface is Ssc It is 0.7 µm ^-1 or more and 3.8 µm ^-1 or less. In addition, when the profile was analyzed by electron beam backscatter diffraction after heating at 200°C for 2 hours, among crystal grains with a crystal grain size of 0.5 µm or more, crystal grains with a crystal grain size of 0.5 µm or more and less than 1.0 µm The ratio R1 of the number of particles is 0.51 or more and 0.97 or less, the ratio R2 of the number of crystal particles whose crystal grain size is 1.0 µm or more and less than 3.0 µm is 0.03 or more and 0.42 or less, and the crystal grain size is 3.0 µm or more The ratio R3 of the number of crystal grains is 0.07 or less. That is, crystal grains having a crystal grain diameter of 3.0 µm or more are arbitrary components, and the ratio R3 is 0 or more and 0.07 or less.

In the surface-treated copper foil according to an embodiment of the present invention, it is further preferable that the arithmetic mean Ssc of the vertex curvature of the roughened surface is 1.0 µm ^-1 or more and 2.5 µm ^-1 or less. In addition, it is preferable to analyze the cross section by electron beam backscatter diffraction after heating at 200°C for 2 hours. Of the crystal grains having a crystal grain size of 0.5 µm or more, the crystal grain size is 0.5 µm or more and less than 1.0 The ratio R1 of the number of crystal particles of µm is 0.59 or more and 0.96 or less, the ratio R2 of the number of crystal particles of 1.0 µm or more and less than 3.0 µm is 0.04 or more and 0.41, and the crystal particle size is 3.0 The ratio R3 of the number of crystal grains above µm is 0.

The surface-treated copper foil of the present embodiment described above has fine wiring processability for forming fine wirings with L&S of, for example, 30 µm/30 µm or less by a reduction method excellent in process cost, and has excellent adhesion to a resin substrate. Therefore, the surface-treated copper foil of this embodiment can be preferably used for manufacturing copper-clad laminates and printed wiring boards, and can produce printed wiring boards with high-density and extremely fine wiring.

In the surface-treated copper foil of this embodiment, the foil thickness is 10 µm or less. If the thickness of the surface-treated copper foil exceeds 10 µm, there is a possibility that the dissolution time of the copper foil becomes longer and the etching factor decreases. In addition, in the surface-treated copper foil of this embodiment, the Rpm of the roughened surface (10-point average of the maximum mountain height of the roughness curve) may also be set to 0.5 µm or more and 3.5 µm or less. If the Rpm of the roughened surface is less than 0.5 µm, there is a possibility that the adhesiveness with the resin substrate may decrease. On the other hand, if the Rpm of the roughened surface exceeds 3.5 µm, there is a risk that the etching factor will decrease.

Furthermore, in the surface-treated copper foil of this embodiment, the tensile strength under normal conditions may be set to 400 MPa or more and 780 MPa or less, and the tensile strength measured at normal temperature after heating at 220°C for 2 hours may also be set to 300 MPa or more. If the tensile strength under normal conditions is 400 MPa or more and 780 MPa or less, the operability and etching properties of the surface-treated copper foil are good. In addition, when the tensile strength measured at room temperature after heating at 220°C for 2 hours is 300 MPa or more, the etching property is good.

In addition, in the present invention, the "crystal grain size" refers to a circle-equivalent diameter. In addition, in the present invention, the “normal state” refers to a state where the surface-treated copper foil is left at normal temperature (that is, about 25° C.) without undergoing thermal history such as heat treatment. The tensile strength under normal conditions can be measured at room temperature by the method according to IPC-TM-650. In addition, the tensile strength after heating can be measured by heating the surface-treated copper foil to 220°C for 2 hours and then naturally cooling to room temperature at room temperature by the same method as the tensile strength under normal conditions.

Hereinafter, the surface-treated copper foil of this embodiment will be described in more detail. First, the method of manufacturing the surface-treated copper foil will be described. (1) About the manufacturing method of electrolytic copper foil The electrolytic copper foil can be manufactured using, for example, the electrolysis device shown in FIG. 1. The electrolysis device of FIG. 1 includes: an insoluble anode 104 containing titanium coated with platinum group elements or their oxides; a cathode drum 102 made of titanium, which is opposed to the insoluble anode 104; and a polishing wheel 103, which is opposite The cathode drum 102 is ground to remove the oxide film generated on the surface of the cathode drum 102.

An electrolyte 105 (a sulfuric acid-copper sulfate aqueous solution) is supplied between the cathode drum 102 and the insoluble anode 104, and while the cathode drum 102 is rotated at a fixed speed, a direct current is connected between the cathode drum 102 and the insoluble anode 104. With this, copper is precipitated onto the surface of the cathode drum 102. The deposited copper was peeled from the surface of the cathode drum 102 and coiled continuously to obtain an electrolytic copper foil 101.

The inventors of the present invention conducted intensive studies and found that the current between the cathode drum 102 and the insoluble anode 104 is caused by the method of generating a strong turbulent flow of the electrolyte 105 compared to the previous method of stirring the electrolyte by the pump The density is more uniform than that of general electrolytic foils, so that the distribution of crystal grains of copper foil can be controlled. As an example of a method for generating a strong turbulent flow of the electrolyte 105, the introduction of gas such as air can be cited. If a gas inlet device is provided in the electrolysis device, the gas is supplied to the electrolyte 105 while the flow rate is adjusted to make the electrolyte 105 bubbly, then the bubbles move randomly in the electrolyte 105 to generate a strong turbulent flow.

Specifically, if the flow rate of the gas is set to 2 L/min or more and 8 L/min or less, the current density can be made uniform, and it is easy to obtain diffraction by electron beam back scattering after heating at 200°C for 2 hours The distribution of crystal grains in the cross-sectional analysis by the method is the same as the electrolytic copper foil of the surface-treated copper foil of the present embodiment described above. If the flow rate of the gas is less than 2 L/min, a region with a low current density is generated locally, and coarse crystal grains are easily formed, so there is a possibility that the etching factor may decrease. On the other hand, if the flow rate of the gas exceeds 8 L/min, the ratio R1 becomes larger and side erosion becomes an advantage, so the etching factor may be reduced.

In addition, as another embodiment, continuous irregularities may be formed on the surface of the insoluble anode. Near the irregularities, the flow rate of the electrolyte is slow. On the other hand, between the insoluble anode and the cathode, the flow rate of the electrolyte becomes faster, resulting in a speed difference. It was found that due to this speed difference, a strong turbulent flow is generated, and the current density distribution is more uniform compared to the previous electrolytic foil making, so that the distribution of the crystal grains of the copper foil can be controlled.

Specifically, a convex portion having a height of 0.5 mm to 1.5 mm and a width of 10 mm to 70 mm is continuously formed along the circumferential direction of the anode with a space of 60 mm, thereby generating turbulent flow, which is easily obtained at 200°C After the heating for 2 hours, the distribution of the crystal grains when analyzing the cross section by the electron beam backscatter diffraction method is the same as the aforementioned electrolytic copper foil of the surface-treated copper foil of the present embodiment.

When manufacturing an electrolytic copper foil, additives may be added to the electrolytic solution 105. The type of additive is not particularly limited, and examples include thiosemicarbazide, polyethylene glycol, tetramethylthiourea, and polypropylene amide. Here, by increasing the amount of thiourea and tetramethylthiourea, the tensile strength under normal conditions and the tensile strength measured at room temperature after heating at 220°C for 2 hours can be increased.

If the tensile strength under normal conditions is 400 MPa or more and 780 MPa or less, the operability and etching properties of the surface-treated copper foil are good. If the tensile strength under normal conditions is less than 400 MPa, the surface-treated copper foil is a thin foil product, so wrinkles may occur during transportation and the handling may deteriorate. On the other hand, if the tensile strength under normal conditions is greater than 780 MPa, when the copper foil is produced using an electrolysis device, the copper foil that has precipitated to the drum is likely to break the foil and is not suitable for manufacturing.

In addition, when the tensile strength measured at room temperature after heating at 220°C for 2 hours is 300 MPa or more, the crystal grains are also heated after the step of manufacturing the copper-clad laminate by laminating the surface-treated copper foil and the resin substrate. Fine and etchable. If the tensile strength measured at room temperature after heating at 220°C for 2 hours does not reach 300 MPa, the crystal grains will change due to the heating in the step of manufacturing the copper-clad laminate by laminating the surface-treated copper foil and the resin substrate It is too large and hardly dissolves in etching, so there is a possibility that the etching property is lowered.

In addition, molybdenum may be added to the electrolytic solution 105. By adding molybdenum, the etching property of copper foil can be improved. Generally, in electrolysis, the copper concentration of the electrolyte 105 (the concentration of copper only in the sulfuric acid component of the copper sulfate) is 13 g/L to 72 g/L, and the sulfuric acid concentration of the electrolyte 105 is 26 g/L to 133 g/L, the liquid temperature of the electrolyte 105 is 18°C to 67°C, the current density is 3 A/dm ² to 67 A/dm ² , and the processing time is 1 second or more and 1 minute 55 seconds or less.

(2) About the surface treatment of electrolytic copper foil >Roughening> It is known that the surface of the electrolytic copper foil is roughened for the purpose of improving the adhesion to the resin substrate to form a roughened surface. However, in general, a roughening treatment with high adhesion is easy during etching. The roots remain, and the etching factor is easily reduced. The inventors of the present invention conducted intensive studies, and found that by slightly dissolving the vertices of the roughened particles, the strength of the vertices' bending degree is reduced (the arithmetic mean Ssc of the vertices of the roughened surface is reduced), and it is not easy to produce roots during etching The etching factor is increased while remaining. The method of dissolving the apexes of the roughened particles is not particularly limited, and examples thereof include: a method of dissolving by pulse plating using a moderate reverse current, and immersing the copper foil in an aqueous solution of copper sulfate after roughening, preferably The method of dissolving the top.

In addition, it was found that if the arithmetic mean Ssc of the vertex curvature of the roughened surface is 0.7 µm ^-1 or more and 3.8 µm ^-1 or less, and after heating at 200°C for 2 hours, the crystal is analyzed by electron beam backscatter diffraction method The distribution of the particles is as described above (that is, when the profile is analyzed by electron beam backscatter diffraction after heating at 200°C for 2 hours, the crystal particle size of the crystal particles with a crystal particle size of 0.5 µm or more is 0.5 µm The ratio R1 of the number of crystal grains above and less than 1.0 µm is 0.51 or more and 0.97, and the ratio R2 of the number of crystal grains whose crystal grain size is 1.0 µm or more and less than 3.0 µm is 0.03 or more and 0.42 or less, The ratio R3 of the number of crystal grains with a crystal grain size of 3.0 µm or more is 0, or when the cross section is analyzed by electron beam backscatter diffraction after heating at 200°C for 2 hours, the crystal grain size is 0.5 µm or more Among the crystal grains, the ratio R1 of the number of crystal grains having a crystal grain diameter of 0.5 µm or more and less than 1.0 µm is 0.51 or more and 0.97 or less, and the number of crystal grains having a crystal grain diameter of 1.0 µm or more and less than 3.0 µm When the ratio R2 is 0.03 or more and 0.42 or less, and the ratio R3 of the number of crystal grains with a crystal particle size of 3.0 µm or more is more than 0 and 0.07 or less), the etching factor of the copper foil increases specifically.

It can be considered that this is caused by a good balance between the dissolution rate in the longitudinal direction (direction from the top side of the wiring toward the bottom side) in the copper foil and the dissolution rate in the roughened surface (lateral direction, that is, the width direction of the wiring) effect. For example, when the dissolution rate of the roughened surface (the dissolution in the horizontal direction) is faster than the dissolution speed of the copper foil (the dissolution in the vertical direction), an under cut will occur (the dissolution of the roughened surface in the horizontal direction is much more advanced than the copper foil Problem).

>Formation of nickel layer, zinc layer, chromate treatment layer> In the surface-treated copper foil of this embodiment, a nickel layer and a zinc layer may be sequentially formed on the roughened surface formed by roughening treatment. The zinc layer plays the role of preventing the deterioration of the resin substrate caused by the reaction of the surface-treated copper foil and the resin-made substrate when the surface-treated copper foil and the resin-made substrate are thermocompression-bonded, and the surface-treated copper foil The surface is oxidized to improve the adhesion between the surface-treated copper foil and the resin substrate. In addition, the nickel layer prevents the zinc of the zinc layer from thermally diffusing into the surface-treated copper foil when the surface-treated copper foil and the resin-made substrate are thermocompression-bonded. That is, the nickel layer functions as a base layer of the zinc layer to effectively exert the above-mentioned functions of the zinc layer.

Furthermore, the nickel layer and the zinc layer can be formed by a well-known electrolytic plating method or electroless plating method. In addition, the nickel layer may be formed of pure nickel, or may be formed of a phosphorus-containing nickel alloy. In addition, if chromate treatment is further performed on the zinc layer, it is preferable to form an antioxidant layer on the surface of the surface-treated copper foil. The applied chromate treatment may be based on a well-known method, and for example, the method disclosed in Japanese Patent Laid-Open No. 60-86894 can be cited. By attaching chromium oxides and their hydrates converted into chromium in an amount of about 0.01 mg/dm ² to about 0.3 mg/dm ² , the surface-treated copper foil can be given an excellent antioxidant function.

>Silane treatment> The surface treated with chromate can be further treated with silane coupling agent (silane treatment). The surface treatment using a silane coupling agent imparts a functional group with a strong affinity to the adhesive to the surface of the surface-treated copper foil (the surface on the bonding side with the resin-made substrate), so the surface-treated copper foil and the resin-made substrate The adhesion is further improved, and the rust resistance and moisture absorption heat resistance of the surface treated copper foil are further improved.

The type of silane coupling agent is not particularly limited, and examples thereof include vinyl silane, epoxy silane, styrene silane, methacrylic silane, acrylic silane, amino silane, urea silane, and chloropropyl Silane, mercapto silane, sulfide silane, isocyanate silane, etc. These silane coupling agents are usually used as aqueous solutions having a concentration of 0.001% by mass or more and 5% by mass or less. After applying this aqueous solution to the surface of the surface-treated copper foil and heating and drying, the silane treatment can be performed. Furthermore, instead of the silane coupling agent, a titanate-based, zirconate-based coupling agent or the like can be used to obtain the same effect.

(3) About the manufacturing method of copper clad laminate and printed circuit board First, surface-treated copper foil is placed on one or both surfaces of an electrically insulating resin substrate made of glass epoxy resin, polyimide resin, or the like. At this time, the roughened surface of the surface-treated copper foil was opposed to the resin substrate. Then, while heating the superposed resin substrate and surface-treated copper foil, while applying pressure in the direction of lamination, the resin substrate and the surface-treated copper foil are joined to obtain a copper-clad laminate with or without a carrier. Since the surface-treated copper foil of this embodiment has a high tensile strength under normal conditions and after heating, it can be adequately handled even without a carrier.

Next, the surface of the copper foil of the copper-clad laminate is irradiated with CO ₂ gas laser to make holes. That is, the surface of the copper foil on which the laser absorption layer is formed is irradiated with CO ₂ gas laser to form a through-hole process that forms a through hole penetrating the surface-treated copper foil and the resin substrate. Then, a circuit such as a high-density wiring circuit is formed on the surface-treated copper foil by a conventional method, so that a printed wiring board can be obtained.

[Example] Hereinafter, Examples and Comparative Examples are shown, and the present invention will be described more specifically. (A) Manufacture of electrolytic copper foil Using the electrolysis device shown in FIG. 1 and using a sulfuric acid-copper sulfate aqueous solution as an electrolytic solution, an electrolytic copper foil was manufactured by the following operation. That is, by supplying the electrolyte between the anode and the cathode drum opposite to the anode, while passing air into the electrolyte and rotating the cathode drum at a fixed speed, a direct current is connected between the anode and the cathode drum. Thus, copper is precipitated onto the surface of the cathode drum. Then, the precipitated copper was peeled from the surface of the cathode drum and continuously wound up, thereby manufacturing an electrolytic copper foil.

The copper concentration, sulfuric acid concentration, and chlorine concentration in the electrolyte are shown in Table 1. In one part of Example 1 to Example 14 and Comparative Example 1 to Comparative Example 5, as shown in Table 1, ethidium thiourea, polyethylene glycol, tetramethylthiourea, And two kinds of glue (molecular weight 20000), the concentration of these additives is shown in Table 1. In addition, the temperature, current density, and air flow rate of the electrolyte when manufacturing the electrolytic copper foil are shown in Table 1. Furthermore, in Examples 13 and 14, convex portions having a height of 1.0 mm and a width of 60 mm were continuously formed at intervals of 60 mm along the circumferential direction of the anode.

[Table 1]

(B) Coarse processing Next, the S surface or the M surface of the electrolytic copper foil (refer to Table 2) is subjected to a roughening treatment to make the surface roughened to produce a surface-treated copper foil. Specifically, electroplating (pulse plating) that electrodeposits fine copper particles onto the surface of an electrolytic copper foil is performed as a roughening process, thereby producing a roughened surface formed with fine irregularities from copper particles. The plating solution used for electroplating contains copper, sulfuric acid, molybdenum, and nickel. The copper concentration, sulfuric acid concentration, molybdenum concentration, and nickel concentration are shown in Table 2.

In addition, the conditions of the roughening treatment, that is, pulse plating (surface to be roughened (treatment surface), electrolytic conditions, plating treatment time, temperature of plating solution) are shown in Table 2. Under the electrolysis conditions in Table 2, Ion1 represents the pulse current density of the first stage, Ion2 represents the pulse current density of the second stage, ton1 represents the pulse current application time of the first stage, ton2 represents the pulse current application time of the second stage , Toff represents the time when the current between the pulse current of the second stage and the pulse current of the first stage is set to 0.

In addition, regarding Example 11, Example 12, and Comparative Example 1, normal plating was performed instead of pulse plating. Under the electrolysis conditions in Table 2, I is the current density of the plating performed in Example 11, Example 12, and Comparative Example 1. Furthermore, regarding Examples 11 and 12, the obtained surface-treated copper foil was further immersed in a copper sulfate bath (copper sulfate aqueous solution) to dissolve the apexes of fine convex portions formed on the surface of the electrolytic copper foil Round, adjust the arithmetic mean Ssc of the vertex curvature of the roughened surface. The copper concentration, sulfuric acid concentration, and immersion time of the copper sulfate bath are shown in Table 2.

[Table 2]

(C) Formation of nickel layer (underlayer) Next, the roughened surface of the surface-treated copper foil is electrolytically plated under the Ni plating conditions shown below, thereby forming a nickel layer (the adhesion amount of Ni is 0.06 mg/dm ² ). The plating solution for nickel plating contains nickel sulfate, ammonium persulfate ((NH ₄ ) ₂ S ₂ O ₈ ), boric acid (H ₃ BO ₃ ), the nickel concentration is 5.0 g/L, and the ammonium persulfate concentration is 40.0 g/L, boric acid concentration is 28.5 g/L. In addition, the temperature of the plating solution is 28.5°C, the pH is 3.8, the current density is 1.5 A/dm ² , and the plating treatment time is 1 second to 2 minutes.

(D) Formation of zinc layer (heat-resistant treatment layer) Furthermore, electrolytic plating is performed on the nickel layer under the Zn plating conditions shown below, thereby forming a zinc layer (Zn adhesion amount 0.05 mg/dm ² ) . The plating solution used for zinc plating contains zinc sulfate heptahydrate and sodium hydroxide. The zinc concentration is 1 g/L to 30 g/L, and the sodium hydroxide concentration is 10 g/L to 300 g/L. In addition, the temperature of the plating solution is 5°C to 60°C, the current density is 0.1 A/dm ² to 10 A/dm ² , and the plating treatment time is 1 second to 2 minutes.

(E) Formation of chromate treatment layer (rust-preventive treatment layer) Furthermore, electrolytic plating is performed on the zinc layer under the Cr plating conditions shown below, thereby forming a chromate treatment layer (adhesion of Cr Amount 0.02 mg/dm ² ). The plating solution used for chromium plating contains chromic anhydride (CrO ₃ ) with a chromium concentration of 2.5 g/L. In addition, the temperature of the plating solution is 15°C to 45°C, the pH is 2.5, the current density is 0.5 A/dm ² , and the plating treatment time is 1 second to 2 minutes.

(F) Formation of silane coupling agent layer Furthermore, the treatment shown below is performed to form a silane coupling agent layer on the chromate treatment layer. That is, methanol or ethanol is added to the aqueous solution of the silane coupling agent, adjusted to a predetermined pH, and a treatment liquid is obtained. The chromate treatment layer of the surface-treated copper foil is coated with this treatment liquid, and after holding for a predetermined time, it is dried by hot air, thereby forming a silane coupling agent layer.

(G) Evaluation As described above, the surface-treated copper foils of Examples 1 to 14 and Comparative Examples 1 to 5 were manufactured, respectively. The thickness of these surface-treated copper foils is shown in Table 3. Various evaluations were performed for each surface-treated copper foil obtained.

>Tensile strength> The surface-treated copper foils of Examples 1 to 14 and Comparative Examples 1 to 5 obtained in the above manner were cut into short strips with a width of 12.7 mm and a length of 130 mm, and used as tensile test pieces. By the method according to IPC-TM-650, the tensile strength of the tensile test piece under normal conditions was measured. As a measurement device, a 1122 type tensile tester of Instron Corporation was used, and the measurement temperature was set to normal temperature. In addition, after heating the tensile test piece at 220°C for 2 hours, it was naturally cooled to normal temperature. For the tensile test piece after such a thermal history was given, the tensile strength was measured in the same manner as the tensile strength under normal conditions. The results are shown in Table 3.

>etching factor> By subtractive method, a resist pattern with L&S of 30 µm/30 µm was formed on the surface-treated copper foils of Examples 1 to 14 and Comparative Examples 1 to 5. Then, etching is performed to form a wiring pattern. As the resist, a dry resist film was used, and as the etching solution, a mixed solution containing copper chloride and hydrochloric acid was used. Then, the etching factor (Ef) of the obtained wiring pattern was measured. The etching factor refers to a value represented by the following formula when the thickness of the copper foil is H, the bottom width of the formed wiring pattern is B, and the top width of the formed wiring pattern is T. Ef＝2H/(B-T) In this embodiment and the comparative example, the test piece having an etching factor of 2.5 or more is regarded as a good product, and the test piece less than 2.5 is regarded as a defective product.

If the etching factor is small, the verticality of the side walls in the wiring pattern collapses, and in the case of fine wiring patterns with narrow line widths, there is a risk of dissolution and residue of copper foil between adjacent wiring patterns, resulting in the risk of short-circuit and wire breakage. Sex. In this test, with respect to the wiring pattern when the etching position becomes appropriate (the position of the end of the resist is aligned with the position of the bottom of the wiring pattern), the bottom width B and the top width T are measured with a microscope, and the etching factor is calculated. The results are shown in Table 3.

[Adhesion] A resin substrate was joined to the roughened surface of the copper foil to prepare a sample for measurement. As the resin substrate, a commercially available polyphenylene ether resin (Ultra Low Transmission Loss Multilayer Substrate Material MEGTRON6 manufactured by Panasonic Corporation) was used, and the curing temperature during bonding was 210°C, and the curing time was 2 hours.

After etching the copper foil of the prepared measurement sample into a circuit wiring with a width of 10 mm, the resin substrate side is fixed to the stainless steel plate with double-sided tape, and the circuit wiring is oriented in a 90-degree direction at a speed of 50 mm/minute Stretched and peeled, and the adhesiveness (kN/m) was measured. The measurement of the adhesion is performed using a universal material testing machine (Tensilon manufactured by A&D Co., Ltd.). In this example and the comparative example, the case where the adhesiveness is 0.4 kN/m or more is regarded as a good product, and the case where it is less than 0.4 kN/m is regarded as a defective product.

[Operability: Number of bad wrinkles] The surface-treated copper foils of Examples 1 to 14 and Comparative Examples 1 to 5 were cut into a square shape with a side of 200 mm, and pressure-bonded to the substrate FR4 to produce a copper-clad laminate. The joining conditions are temperature 170°C, pressure 1.5 MPa, and pressurization time 1 hour. For each surface-treated copper foil, 30 pieces of copper-clad laminates were produced, and the wrinkles of the copper foil were visually confirmed, and the number of copper-clad laminates with wrinkles in the copper foil (the number of defective wrinkles) was counted. Based on the number of wrinkles, the operability of the surface-treated copper foil was evaluated. When the number of wrinkle defects is 3 or less, it is regarded as a pass, and when it is 4 or more, it is regarded as a pass. The results are shown in Table 3.

[Vertical Curvature Arithmetic Average Ssc, Rpm] The surface shape of the roughened surface of the surface-treated copper foil of Examples 1 to 14 and Comparative Examples 1 to 5 was measured using Wyko ContourGT-K, a three-dimensional white light interference microscope of BRUKER, and the shape was analyzed to obtain The vertex curvature arithmetic mean Ssc and Rpm. The shape analysis system uses a high-resolution CCD (charge coupled device) camera in a VSI (Virtual Switch Interface) measurement method. The conditions are set to white light source, measuring magnification of 10 times, measuring range of 477 µm × 357.8 µm, lateral sampling (Lateral Sampling) 0.38 µm, speed (speed) 1, back scanning height (Backscan) 10 µm , Length (Length) is 10 µm, Threshold (Threshold) is 3%, Project Removal (Cylinder and Tilt), Data Restore (Methods: legacy, iterations 5), Statistics After filtering (Statistic Filter) (Filter Size: 3, Filter Type: Median), data processing is performed. The results are shown in Table 3.

[Distribution of crystal grains] Use EBSD (Electron Back Scatter Diffraction) camera Hikari/DC5.2/A5.2 of TSL Solutions Co., Ltd. and scanning electron microscope JSM-7001FA of JEOL, The crystal grains of the roughened surface of the surface-treated copper foil were measured under the conditions of a magnification of 5000 times and a beam step of 0.05. In the measurement of crystal grains by EBSD, the crystal grain boundaries with an orientation difference of 15° or more are set, and the area surrounded by the crystal grain boundaries is set as crystal grains.

At this time, CP (Cross Section Polisher, cross-section polisher) polishing was performed on the cut surface of the surface-treated copper foil, and EBSD was measured on the part of the polished surface within the range shown in FIG. 2. That is, when the foil thickness of the surface-treated copper foil is set to t, as shown in FIG. 2, the vertical (length in the thickness direction) 0.8 t and the horizontal (positive to the thickness direction) of the surface in contact with the surface opposite to the roughened surface The length of the direction of intersection) 1.6 t rectangular area, measured EBSD. For example, when the foil thickness t is 10 µm, it becomes a rectangular area of 8.0 µm in length and 16.0 µm in width. When the foil thickness t is 6 µm, it becomes a rectangular area of 4.8 µm in length and 9.6 µm in width. The foil thickness t is 4 µm At this time, it becomes a rectangular area of 3.2 µm in length and 6.4 µm in width. Based on the data of GBSD SIZE of EBSD (Electron Beam Backscatter Diffraction Method), the aforementioned ratios of crystal grains R1, R2, R3 are calculated. The results are shown in Table 3.

[table 3]

Comparative Example 1 is a copper foil manufactured under known foil-making conditions (Example 2 of Japanese Patent No. 4583149), but since the ratio R3 of the number of crystal grains is large, the etching factor (Ef) is small and cannot be Make L&S thinner. Comparative Example 2 has a smaller flow rate than Example 3, so the ratio of the number of crystal grains R2 and R3 becomes large, and the L&S cannot be made fine.

In Comparative Example 3, since the inflow rate is too large, the ratio R1 of the number of crystal grains becomes large, and the L&S cannot be made fine. In Comparative Example 4, as compared with Example 1, the reverse current was not applied with the pulse current of the roughening process and the coarsened particles were not dissolved, so the etching factor was reduced. In Comparative Example 5, since the current of the roughening process is large, the coarsened particles become coarse, which causes the root residue to easily occur during etching, and the etching factor decreases.

101‧‧‧Electrolytic copper foil 102‧‧‧Cathode drum 103‧‧‧ Polishing wheel 104‧‧‧Insoluble anode 105‧‧‧Electrolyte

FIG. 1 is a diagram illustrating a method of manufacturing an electrolytic copper foil using an electrolysis device. Fig. 2 is a diagram illustrating a method for measuring the distribution of crystal grains.

Domestic storage information (please note in order of storage institution, date, number) no

Overseas hosting information (please note in order of hosting country, institution, date, number) no

Claims (6)

A surface-treated copper foil, which is a surface-treated copper foil having a roughened surface formed by roughening treatment on the surface, and the foil thickness is 10 µm or less, and the arithmetic mean Ssc of the vertex curvature of the roughened surface is 0.7 µm ^-1 or more And when the profile is analyzed by electron beam backscatter diffraction after heating for 2 hours at 200°C for 3.8µm ^-1 or less, among the crystal grains with a crystal grain size of 0.5µm or more, the crystal grain size is 0.5µm or more and not The ratio R1 of the number of crystal grains up to 1.0µm is 0.51 or more and 0.97, the ratio R2 of the number of crystal grains of 1.0µm or more and less than 3.0µm is 0.03 or more and 0.42, the crystal grain size The ratio R3 of the number of crystal grains of 3.0 µm or more is 0.07 or less. The surface-treated copper foil according to claim 1, wherein the arithmetic mean Ssc of the vertex curvature of the roughened surface is 1.0 µm ^-1 or more and 2.5 µm ^-1 or less, the aforementioned ratio R1 is 0.59 or more and 0.96 or less, and the aforementioned ratio R2 It is 0.04 or more and 0.41 or less, and the aforementioned ratio R3 is 0. The surface-treated copper foil according to claim 1 or 2, wherein the Rpm of the roughened surface is 0.5 µm or more and 3.5 µm or less. The surface-treated copper foil according to any one of claims 1 to 3, wherein the tensile strength under normal conditions is 400 MPa or more and 780 MPa or less, and the tensile strength measured at ordinary temperature after heating at 220°C for 2 hours It is more than 300MPa. A copper-clad laminate comprising the surface-treated copper foil as described in any one of claims 1 to 4 and a resin substrate laminated on the roughened surface of the surface-treated copper foil. A printed wiring board equipped with a copper-clad laminate as described in item 5 of the patent application scope.

Images