JP6606317B1 - Surface-treated copper foil, copper-clad laminate, and printed wiring board - Google Patents

Abstract

Providing a surface-treated copper foil that has fine wiring processability that allows formation of fine wiring with an L & S of, for example, 30/30 μm or less, and excellent adhesion to a resin substrate by a subtractive construction method that excels in process costs. To do. A surface-treated copper foil having a roughened surface by a roughening treatment, the foil thickness is 10 μm or less, and the vertex curvature arithmetic average Ssc of the roughened surface is 0.7 μm−1 or more and 3.8 μm−1 or less. is there. 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 and less than 1.0 μm among the crystal grains having a crystal grain size of 0.5 μm or more. The ratio R1 of the number of crystal grains is 0.51 or more and 0.97 or less, 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 having a crystal grain size of 3.0 μm or more is 0.07 or less.

Description

  The present invention uses a surface-treated copper foil excellent in fine wiring workability suitable for a printed wiring board or the like having a high-density wiring circuit (fine pattern), and adhesion to a resin substrate, and the surface-treated copper foil. The present invention relates to a copper-clad laminate and a printed wiring board.

  As a copper foil used for a copper clad laminate or a printed wiring board, an electrolytic copper foil obtained by peeling a copper foil deposited on a drum of an electrolytic deposition apparatus from the drum is used. The electrolytic deposition starting surface (shiny surface; hereinafter referred to as “S surface”) of the electrolytic copper foil peeled from the drum is relatively smooth and the electrolytic deposition finish surface (matt surface; hereinafter referred to as the opposite surface). , "M-plane") generally has irregularities. A copper-clad laminate is manufactured by placing a resin substrate on the M surface of the electrolytic copper foil and thermocompression bonding. By roughening the M surface by roughening, adhesion to the resin substrate is achieved. It is improving.

  Recently, an adhesive resin such as an epoxy resin is pasted on the roughened surface of the copper foil in advance, and the resin-coated copper foil is used for forming a surface circuit by using the adhesive resin as an insulating resin layer in a semi-cured state (B stage). A printed wiring board (particularly a build-up wiring board) is manufactured by thermocompression bonding the insulating resin layer side to an insulating substrate. In the build-up wiring board, it is required to highly integrate various electronic components. Correspondingly, the wiring pattern is also required to have a high density, and a wiring pattern having a fine line width and a pitch between lines, so-called fine wiring. There is a growing demand for printed wiring boards with patterns. For example, multilayer boards used for servers, routers, communication base stations, in-vehicle boards, etc. and multilayer boards for smartphones require printed wiring boards with high density and extremely fine wiring (hereinafter referred to as “high density wiring boards”). Has been.

  High-layer wiring boards of AnyLayer (interlayer connection using laser vias with a high degree of freedom in arrangement) are mainly used for the main board of smartphones. Wiring with a pitch (hereinafter referred to as “L & S”) of 30 μm or less is required. A high-density wiring board is conventionally manufactured by a subtractive method using a photoresist in a printed wiring board manufacturer. However, since the cross-sectional shape of the wiring collapses when the L & S becomes narrow, it has a large area exceeding 500 mm square. When a high-density wiring board is formed at once, it has been difficult to form a wiring having an L & S of 30/30 μm (the line width (L) is 30 μm and the pitch between lines (S) is 30 μm) or less.

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

Patent Document 1 discloses a technique for forming a fine wiring by refining the average crystal grain size of the bulk of an ultrathin copper layer. However, if the crystal grain size is too small, side etching (the side of the wiring cross section) is disclosed. There was a possibility that a high etching factor could not be obtained due to the influence of (directional etching).
Further, Patent Document 2 discloses a copper foil that is excellent in adhesion to a high heat-resistant resin. However, sharpened rough particles are likely to remain undissolved during etching (root residue), and fine wiring processing. There was a risk that the property would be insufficient.

Japanese Patent Gazette No. 6158573 Japanese Patent Publication No. 2010 No. 236058

  The present invention is a subtractive method with excellent process cost, and has a fine wiring workability capable of forming fine wiring with an L & S of, for example, 30/30 μm or less, and a surface treatment excellent in adhesion to a resin substrate. It is an object to provide a copper foil. Another object 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 ultrafine wiring.

The surface-treated copper foil according to one embodiment of the present invention is a surface-treated copper foil having a roughened surface by a roughening treatment on the surface, the foil thickness is 10 μm or less, and the vertex curvature arithmetic average Ssc of the roughened surface is 0.7 [mu] m ^-1 or 3.8 .mu.m ^-1 or less, when analyzing the cross-section by electron backscatter diffraction after heating 2 hours at 200 ° C., of grain size of more crystal grains 0.5 [mu] m, The ratio R1 of the number of crystal grains having a crystal grain size 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 size of 1.0 μm or more and less than 3.0 μm The gist is that the ratio R3 is 0.03 or more and 0.42 or less, and the ratio R3 of the number of crystal grains having a crystal grain size of 3.0 μm or more is 0.07 or less.

Moreover, the copper clad laminated board which concerns on the other aspect of this invention is provided with the surface-treated copper foil which concerns on the said one aspect, and the resin-made board | substrate laminated | stacked on the roughening surface of this surface-treated copper foil. And
Furthermore, the gist of the printed wiring board according to another aspect of the present invention is that it includes the copper-clad laminate according to the other aspect.

  The surface-treated copper foil of the present invention has a fine wiring processability capable of forming a fine wiring having an L & S of, for example, 30/30 μm or less by a subtractive method with excellent process cost, and is in close contact with a resin substrate. Excellent in properties. Moreover, the copper clad laminated board of this invention has the above fine wiring processability. Furthermore, the printed wiring board of the present invention has high density and extremely fine wiring.

It is a figure explaining the method of manufacturing an electrolytic copper foil using an electrolytic deposition apparatus. It is a figure explaining the measuring method of distribution of a crystal grain.

  An embodiment of the present invention will be described. 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 forms to which such changes or improvements are added can also be included in the present invention.

  As a result of intensive studies, the present inventors have found that the distribution of crystal grains having a crystal grain size of 0.5 μm or more in the copper foil is highly influenced by the fine wiring processability of the copper foil. In general, it is known that in the fine wiring etching process, the dissolution proceeds preferentially at the grain boundaries of the crystal grains rather than within the crystal grains. A crystal grain boundary is a boundary between crystal grains having different plane orientations, and is in an energetically active state because there are many atomic arrangement mismatches and defects, so that it is easily dissolved by etching. Therefore, it is considered that the crystal grain boundaries increase and the dissolution rate increases as the crystal grains in the copper foil become finer.

  As a result of investigating factors affecting the improvement of the fine wiring workability of the copper foil, when the crystal grains having a crystal grain size of 0.5 μm or more and less than 1.0 μm are in a certain ratio after being heated at 200 ° C. for 2 hours It was found that the vertical dissolution rate during etching increased and the etching factor increased. However, on the other hand, if the proportion of crystal grains of this size is too large, the horizontal melting on 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 given priority. As a result, it was found that the etching factor decreased.

  Specifically, 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 and 1. When the ratio R1 of the number of crystal grains less than 0 μm is 0.51 or more and 0.97 or less, the etching factor increases. However, if the ratio R1 is larger than 0.97, the etching on the top side preferentially proceeds and the fine wiring workability deteriorates. If the ratio R1 is smaller than 0.51, the etching rate in the thickness direction of the copper foil is reduced. Slows down and fine wiring processing decreases.

  Further, when the crystal grain size is 3.0 μm or more, the area of the grain boundary is small with respect to the volume of the crystal grains and it is easy to remain undissolved. Specifically, a crystal having a crystal grain size of 3.0 μm or more among crystal grains having a crystal grain size of 0.5 μm or more when the cross section is analyzed by electron beam backscatter diffraction after heating at 200 ° C. for 2 hours. Fine wiring workability is improved when the ratio R3 of the number of grains is 0 or in the range of more than 0 and less than or equal to 0.07. However, if the ratio R3 is greater than 0.07, melting of large crystal grains is improved. The remaining effect increases and the fine wiring processability decreases.

Although details will be described later, the distribution of crystal grains as described above can be controlled by making the current density applied to the electrolytic solution uniform when manufacturing the electrolytic copper foil.
Furthermore, in investigating factors contributing to fine wiring workability, it was found that the influence of the arithmetic mean of the curvature (the average curvature of the top surface of the roughened surface) Ssc in the vicinity of the top of the roughened particles of the copper foil is strong. . Specifically, the etching factor increases when the vertex curvature arithmetic average Ssc is 0.7 μm ⁻¹ or more and 3.8 μm ⁻¹ or less. The vertex curvature arithmetic average Ssc is an average summit curvature of various mountain structures, and is expressed by the following equation. In the following formula, z (x, y) is a coordinate in the height direction in the x, y coordinate, and N is the number of vertices of the roughened particles.

  When there is a vertex curvature arithmetic average Ssc in this range, since the degree of bending of the vertices of the roughened particles on the roughened surface of the copper foil is in an appropriate state, the root residue (the tip of the roughened particles remains undissolved) during etching. It is considered that the film is easily melted without being in a state), and the skirting of the copper foil is suppressed to increase the etching factor.

When the vertex curvature arithmetic average Ssc is larger than 3.8 μm ⁻¹ , the degree of bending of the roughened particles is strong, so that the roughened particles are deeply stuck in the resin substrate, resulting in a root residue during etching. The skirting of the copper foil becomes longer and the etching factor decreases. When the vertex curvature arithmetic average Ssc is smaller than 0.7 μm ⁻¹ , the degree of bending of the roughened particles on the resin substrate is poor (because the anchor effect is weak) because the degree of bending of the vertex of the roughened particles is loose. Adhesion between the substrate and copper foil is reduced.

  Although details will be described later, since the vertex curvature arithmetic average Ssc can be lowered by dissolving the vertices of the roughened particles, roughening is performed by pulse plating or a method of immersing the copper foil in an aqueous copper sulfate solution after the roughening treatment. If the vertices of the chemical particles are dissolved, the vertex curvature arithmetic average Ssc can be controlled.

That is, the surface-treated copper foil according to one embodiment of the present invention is a surface-treated copper foil having a roughened surface by a roughening treatment on the surface, the foil thickness is 10 μm or less, and the vertex curvature arithmetic of the roughened surface. The average Ssc is 0.7 μm ⁻¹ or more and 3.8 μm ⁻¹ or less. And, when the cross section is analyzed by electron beam backscatter diffraction after heating at 200 ° C. for 2 hours, among 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 μm The ratio R1 of the number of crystal grains is 0.51 or more and 0.97 or less, 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 having a crystal grain size of 3.0 μm or more is 0.07 or less. That is, a crystal grain having a crystal grain size of 3.0 μm or more is an optional component, and the ratio R3 is 0 or is greater than 0 and not greater than 0.07.

In the surface-treated copper foil according to an embodiment of the present invention, further, the vertex curvature arithmetic mean Ssc of the roughened surface is preferably 1.0 .mu.m ^-1 or 2.5 [mu] m ^-1 or less. In addition, 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 and less than 1.0 μm among the crystal grains having a crystal grain size of 0.5 μm or more. The ratio R1 of the number of crystal grains is 0.59 or more and 0.96 or less, and the ratio R2 of the number of crystal grains whose crystal grain diameter is 1.0 to 3.0 μm is 0.04 or more and 0.41 or less. The ratio R3 of the number of crystal grains having a diameter of 3.0 μm or more is preferably 0.

  The surface-treated copper foil according to the present embodiment has a fine wiring processability capable of forming a fine wiring having an L & S of, for example, 30/30 μm or less by a subtractive method with excellent process cost, and is made of resin. Excellent adhesion to the substrate. Therefore, the surface-treated copper foil according to the present embodiment can be suitably used for the production of copper-clad laminates and printed wiring boards, and can produce printed wiring boards having high-density ultrafine wiring. .

In the surface-treated copper foil according to this embodiment, the foil thickness is 10 μm or less. If the foil thickness of the surface-treated copper foil exceeds 10 μm, there is a possibility that inconvenience that the melting time of the copper foil becomes long and the etching factor decreases.
Moreover, in the surface-treated copper foil which concerns on this embodiment, Rpm (10-point average of the maximum peak height of a roughness curve) of a roughening surface is good also as 0.5 to 3.5 micrometer. When the Rpm of the roughened surface is less than 0.5 μm, there is a possibility that inconvenience that the adhesion to the resin substrate is lowered. On the other hand, if the Rpm of the roughened surface exceeds 3.5 μm, there is a possibility that an inconvenience that the etching factor is lowered.

Furthermore, in the surface-treated copper foil according to this embodiment, the tensile strength in a normal state may be 400 MPa or more and 780 MPa or less, and the tensile strength measured at room temperature after heating at 220 ° C. for 2 hours may be 300 MPa or more.
When the tensile strength in the normal state is 400 MPa or more and 780 MPa or less, the handling property and etching property of the surface-treated copper foil are good. 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 the present invention, “crystal grain size” means an equivalent circle diameter. In the present invention, the “normal state” means that the surface-treated copper foil is kept at a normal temperature (ie, about 25 ° C.) without receiving a thermal history such as heat treatment. The tensile strength in the normal state can be measured at room temperature by a method based on IPC-TM-650. The tensile strength after heating can be measured at room temperature by the same method as the tensile strength in a normal state after heating the surface-treated copper foil to 220 ° C. and holding it for 2 hours, and then naturally cooling it to room temperature.

Below, the surface-treated copper foil which concerns on this embodiment is demonstrated in detail. First, the manufacturing method of surface-treated copper foil is demonstrated.
(1) About the manufacturing method of electrolytic copper foil Electrolytic copper foil can be manufactured, for example using an electrolytic deposition apparatus as shown in FIG. The electrolytic deposition apparatus of FIG. 1 polishes an insoluble anode 104 made of titanium coated with a platinum group element or its oxide, a titanium cathode drum 102 provided opposite to the insoluble anode 104, and the cathode drum 102. And a buff 103 for removing an oxide film generated on the surface of the cathode drum 102.

  An electrolytic solution 105 (sulfuric acid-copper sulfate aqueous solution) is supplied between the cathode drum 102 and the insoluble anode 104, and a direct current is applied between the cathode drum 102 and the insoluble anode 104 while rotating the cathode drum 102 at a constant speed. Energize. As a result, copper is deposited on the surface of the cathode drum 102. The deposited copper is peeled off from the surface of the cathode drum 102 and continuously wound up, whereby the electrolytic copper foil 101 is obtained.

  As a result of intensive studies by the present inventors, the current density between the cathode drum 102 and the insoluble anode 104 is increased by a method of generating a strong turbulent flow in the electrolytic solution 105 compared to the conventional method of stirring the electrolytic solution by a pump. Has been found to be more uniform than general electrolytic foils and to control the distribution of crystal grains of the copper foil. As an example of a method for generating a strong turbulent flow in the electrolytic solution 105, bubbling of a gas such as air can be given. When a gas bubbling device is provided in the electrolytic deposition apparatus and gas is supplied to the electrolytic solution 105 while bubbling while adjusting the flow rate, bubbles move randomly in the electrolytic solution 105 and a strong turbulent flow is generated.

  Specifically, when the gas flow rate is 2 L / min or more and 8 L / min or less, the current density becomes uniform, and the crystal grains when the cross section is analyzed by electron beam backscatter diffraction after heating at 200 ° C. for 2 hours It is easy to obtain an electrolytic copper foil having the same distribution as the surface-treated copper foil according to this embodiment described above. When the gas flow rate is less than 2 L / min, a region where the current density is locally generated is generated, and coarse crystal grains are likely to be formed, so that the etching factor may be reduced. On the other hand, if the gas flow rate is more than 8 L / min, the ratio R1 increases and side etching becomes dominant, which may reduce the etching factor.

  As another embodiment, continuous irregularities may be formed on the surface of the insoluble anode. In the vicinity of the unevenness, the flow rate of the electrolytic solution is low, while the flow rate of the electrolytic solution is high between the insoluble anode and the cathode, resulting in a speed difference. It has been found that a strong turbulent flow is generated by this speed difference, the current density distribution is made more uniform than that of the conventional electrolytic foil, and the crystal grain distribution of the copper foil can be controlled.

  Specifically, the turbulent flow is formed by continuously forming convex portions having a height of 0.5 to 1.5 mm and a width of 10 to 70 mm at intervals of 60 mm along the circumferential direction of the anode. When the cross section is analyzed by electron beam backscatter diffraction after heating at 200 ° C. for 2 hours, an electrolytic copper foil similar to the surface-treated copper foil according to this embodiment described above is obtained. Cheap.

  In the production of the electrolytic copper foil, an additive may be added to the electrolytic solution 105. The type of additive is not particularly limited, and examples thereof include ethylene thiourea, polyethylene glycol, tetramethyl thiourea, polyacrylamide and the like. Here, by increasing the addition amount of ethylenethiourea and tetramethylthiourea, the tensile strength in a normal state and the tensile strength measured at room temperature after heating at 220 ° C. for 2 hours can be improved.

  When the tensile strength in the normal state is 400 MPa or more and 780 MPa or less, the handling property and etching property of the surface-treated copper foil are good. When the tensile strength in a normal state is less than 400 MPa, the surface-treated copper foil is a thin foil sheet product, and thus wrinkles are generated during transportation, which may deteriorate handling properties. On the other hand, if the tensile strength in the normal state is larger than 780 MPa, the copper foil deposited on the drum is likely to break the foil when producing the copper foil using the electrolytic deposition apparatus, which may be unsuitable for production.

  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 after being heated in the process of manufacturing the copper-clad laminate by laminating the surface-treated copper foil and the resin substrate The grains are fine and the etching property is good. When the tensile strength measured at room temperature after heating at 220 ° C. for 2 hours is less than 300 MPa, the crystal grains become larger by etching in the process of producing a copper-clad laminate by laminating a surface-treated copper foil and a resin substrate. Since it becomes difficult to melt | dissolve, there exists a possibility that etching property may fall.

Note that molybdenum may be added to the electrolytic solution 105. By adding molybdenum, the etching property of the copper foil can be enhanced. Usually, in electrolytic deposition, the electrolytic solution 105 has a copper concentration (concentration of only copper sulfate that does not consider the sulfuric acid content) of 13 to 72 g / L, the electrolytic solution 105 has a sulfuric acid concentration of 26 to 133 g / L, and the electrolytic solution. The liquid temperature of 105 is 18 to 67 ° C., the current density is 3 to 67 A / dm ² , and the treatment time is 1 second to 1 minute 55 seconds.

(2) Surface treatment of electrolytic copper foil <roughening treatment>
For the purpose of improving the adhesion to the resin substrate, the surface of the electrolytic copper foil is roughened to form a roughened surface. It is known that it tends to occur and the etching factor tends to decrease. As a result of intensive studies by the present inventors, the strength of the bending of the vertexes is reduced by slightly dissolving the vertices of the roughened particles (the vertex curvature arithmetic mean Ssc of the roughened surface is lowered), and the roots during etching are reduced. It has been found that the etching factor is improved because it is difficult to remain.
The method of dissolving the top of the roughened particles is not particularly limited, but the method of dissolving by pulse plating using an appropriate reverse current, or the copper foil is immersed in an aqueous copper sulfate solution after the roughening treatment is preferential. And a method for dissolving the tip.

The crystal in the case where the vertex curvature arithmetic mean Ssc of the roughened surface is 0.7 μm ⁻¹ or more and 3.8 μm ⁻¹ or less and the cross section is analyzed by electron beam backscatter diffraction after heating at 200 ° C. for 2 hours. The distribution of grains is as described above (that is, when the cross section is analyzed by electron beam backscatter diffraction after heating at 200 ° C. for 2 hours, among the grains having a grain size of 0.5 μm or more, the grain size is 0 The ratio R1 of the number of crystal grains having a size of 0.5 μm or more and less than 1.0 μm is 0.51 or more and 0.97 or less, and the ratio R2 of the number of crystal grains having a grain size of 1.0 μm or more and less than 3.0 μm is 0.8. The ratio R3 of the number of crystal grains of 03 to 0.42 and the crystal grain size of 3.0 μm or more is 0, or the cross section is analyzed by electron beam backscatter diffraction after heating at 200 ° C. for 2 hours When the crystal grain size is 0.5 μm or more, The ratio R1 of the number of crystal grains having a crystal grain size 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 size 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 having a crystal grain size of 3.0 μm or more is more than 0 and 0.07 or less, the etching factor of the copper foil is It was found to rise specifically.

  This is due to the good balance between the dissolution rate in the vertical direction (direction from the top side of the wiring toward the bottom side) of the copper foil and the dissolution rate on the roughened surface (lateral direction, that is, the width direction of the wiring). It is considered to be an effect. For example, when the dissolution rate of the roughened surface (dissolution in the horizontal direction) is too fast than the dissolution rate of the copper foil (dissolution in the vertical direction), the undercut (dissolution of the roughened surface in the horizontal direction than the copper foil) Problem).

<Formation of nickel layer, zinc layer, chromate treatment layer>
In the surface-treated copper foil according to the present embodiment, a nickel layer and a zinc layer may be further formed in this order on the roughened surface formed by the roughening treatment.
The zinc layer prevents deterioration of the resin substrate and surface oxidation of the surface-treated copper foil due to the reaction between the surface-treated copper foil and the resin substrate when the surface-treated copper foil and the resin substrate are thermocompression bonded. Thus, it functions to improve the adhesion between the surface-treated copper foil and the resin substrate. The nickel layer prevents the zinc in the zinc layer from being thermally diffused into the surface-treated copper foil when the surface-treated copper foil and the resin substrate are thermocompression bonded. That is, the nickel layer functions as a base layer for the zinc layer for effectively exhibiting the functions of the zinc layer.

These nickel layers and zinc layers can be formed by applying a known electrolytic plating method or electroless plating method. The nickel layer may be formed of pure nickel or a phosphorus-containing nickel alloy.
Further, it is preferable to further perform chromate treatment on the zinc layer because an antioxidant layer is formed on the surface of the surface-treated copper foil. As the chromate treatment to be applied, a known method can be used. For example, the method disclosed in JP-A-60-86894 can be exemplified. An excellent antioxidant function can be imparted to the surface-treated copper foil by attaching about 0.01 to 0.3 mg / dm ² of chromium oxide and its hydrate in terms of the amount of chromium.

<Silane treatment>
A surface treatment (silane treatment) using a silane coupling agent may be further performed on the chromated surface. The surface treatment using a silane coupling agent gives a functional group having a strong affinity for the adhesive to the surface of the surface-treated copper foil (the surface on the side bonded to the resin substrate). Adhesion with the substrate is further improved, and the rust prevention and moisture absorption heat resistance of the surface-treated copper foil are further improved.

  The type of silane coupling agent is not particularly limited, but vinyl silane, epoxy silane, styryl silane, methacryloxy silane, acryloxy silane, amino silane, ureido silane, chloropropyl silane, mercapto Examples thereof include silane coupling agents such as silane, sulfide silane and isocyanate silane. These silane coupling agents are usually used in the form of an aqueous solution having a concentration of 0.001% by mass or more and 5% by mass or less. Silane treatment can be performed by applying this aqueous solution to the surface of the surface-treated copper foil and then drying by heating. In addition, it can replace with a silane coupling agent, and even if it uses coupling agents, such as a titanate type | system | group and a zirconate type | system | group, the same effect can be acquired.

(3) About the manufacturing method of a copper clad laminated board and a printed wiring board First, surface-treated copper foil is piled up on one or both surfaces of the electrically insulating resin-made board | substrates which consist of glass epoxy resin, a polyimide resin, etc. At that time, the roughened surface of the surface-treated copper foil is opposed to the resin substrate. And while heating the laminated resin substrate and the surface-treated copper foil, applying pressure in the laminating direction to join the resin substrate and the surface-treated copper foil, a copper-clad laminate with or without a carrier is obtained. It is done. Since the surface-treated copper foil according to the present embodiment has a high tensile strength after normal and heating, it can sufficiently cope even without a carrier.

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

〔Example〕
The present invention will be described more specifically with reference to the following examples and comparative examples.
(A) Production of electrolytic copper foil Using the electrolytic deposition apparatus shown in FIG. 1, an electrolytic copper foil was produced by the following operation using a sulfuric acid-copper sulfate aqueous solution as an electrolytic solution. That is, an electrolytic solution is supplied between the anode and a cathode drum provided opposite to the anode, air is bubbled through the electrolytic solution, and the cathode drum is rotated at a constant speed, while the anode and the cathode drum are rotated. By applying a direct current to the copper, copper was deposited on the surface of the cathode drum. And the copper which precipitated was peeled off from the surface of the cathode drum, and the electrolytic copper foil was manufactured by winding up continuously.

  The copper concentration, sulfuric acid concentration, and chlorine concentration in the electrolytic solution are as shown in Table 1. In some of Examples 1 to 14 and Comparative Examples 1 to 5, as shown in Table 1, as an additive to the electrolyte, ethylenethiourea, polyethylene glycol, tetramethylthiourea, and glue (molecular weight 20000) Two types were added, and the concentrations of these additives are as shown in Table 1. Further, the temperature of the electrolytic solution, the current density, and the bubbling flow rate of air during the production of the electrolytic copper foil are as shown in Table 1. Further, 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.

(B) Roughening process Next, the roughening process which makes a surface a roughening surface was given to the S surface or M surface (refer Table 2) of electrolytic copper foil, and the surface-treated copper foil was manufactured. Specifically, electroplating (pulse plating) for electrodepositing fine copper particles on the surface of the electrolytic copper foil was performed as a roughening treatment to obtain a roughened surface on which fine irregularities were formed by the 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 as shown in Table 2.

  Table 2 shows the conditions of the roughening treatment, that is, the pulse plating (the surface subjected to the roughening treatment (treated surface), the electrolysis conditions, the plating time, and the temperature of the plating solution). In the electrolysis conditions in Table 2, Ion1 represents the first-stage pulse current density, Ion2 represents the second-stage pulse current density, ton1 represents the first-stage pulse current application time, and ton2 represents the second-stage pulse current density. Pulse current application time, and toff represents the time when the current between the two-stage pulse current and the first-stage pulse current is zero.

In Examples 11 and 12 and Comparative Example 1, normal electroplating was performed instead of pulse plating. In the electrolysis conditions in Table 2, I is the current density of electroplating performed in Examples 11 and 12 and Comparative Example 1.
Furthermore, about Example 11 and 12, the surface treatment copper foil obtained was further immersed in a copper sulfate bath (copper sulfate aqueous solution), thereby dissolving the apex of fine convex portions formed on the surface of the electrolytic copper foil. Then, the vertex curvature arithmetic average Ssc of the roughened surface was adjusted. The copper concentration, sulfuric acid concentration, and immersion time of the copper sulfate bath are as shown in Table 2.

(C) Formation of Nickel Layer (Underlayer) Next, a nickel layer (amount of Ni deposited: 0.06 mg / dm) is obtained by electrolytic plating on the roughened surface of the surface-treated copper foil under the Ni plating conditions shown below. ² ) formed. The plating solution used for nickel plating contains nickel sulfate, ammonium persulfate ((NH ₄ ) ₂ S ₂ O ₈ ), boric acid (H ₃ BO ₃ ), nickel concentration is 5.0 g / L, ammonium persulfate The concentration is 40.0 g / L and the boric acid concentration is 28.5 g / L. 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 time is 1 second to 2 minutes.

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

(E) Formation of chromate treatment layer (rust prevention treatment layer) Further, the chromate treatment layer (Cr adhesion amount 0.02 mg / dm ² ) is formed on the zinc layer by electrolytic plating under the following Cr plating conditions. Formed. The plating solution used for chromium plating contains chromic anhydride (CrO ₃ ), and the chromium concentration is 2.5 g / L. The temperature of the plating solution is 15 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 Further, the following treatment was performed to form a silane coupling agent layer on the chromate treatment layer. That is, methanol or ethanol was added to the aqueous silane coupling agent solution to adjust the pH to a predetermined value to obtain a treatment liquid. This treatment liquid was applied to the chromate treatment layer of the surface-treated copper foil, held for a predetermined time, and then dried with warm air to form a silane coupling agent layer.

(G) Evaluation The surface-treated copper foils of Examples 1 to 14 and Comparative Examples 1 to 5 were produced as described above. The foil thicknesses of these surface-treated copper foils are as shown in Table 3. Various evaluation was performed about each obtained surface-treated copper foil.

[Tensile strength]
The surface-treated copper foils of Examples 1 to 14 and Comparative Examples 1 to 5 obtained as described above were cut into strips having a width of 12.7 mm and a length of 130 mm to obtain tensile test pieces. The tensile strength of the tensile test piece in a normal state was measured by a method based on IPC-TM-650. An Instron 1122 type tensile tester was used as the measuring device, and the measurement temperature was room temperature.
The tensile test piece was heated at 220 ° C. for 2 hours and then naturally cooled to room temperature. About the tensile test piece which provided such a heat history, the tensile strength was measured like the tensile strength in a normal state. The results are shown in Table 3.

[Etching factor]
A resist pattern having an L & S of 30/30 μm was formed on the surface-treated copper foils of Examples 1 to 14 and Comparative Examples 1 to 5 by the subtractive construction method. Etching was then performed to form a wiring pattern. A dry resist film was used as the resist, and a mixed solution containing copper chloride and hydrochloric acid was used as the etching solution. Then, the etching factor (Ef) of the obtained wiring pattern was measured. The etching factor is a value represented by the following equation, where H is the thickness of the copper foil, B is the bottom width of the formed wiring pattern, and T is the top width of the formed wiring pattern.
Ef = 2H / (BT)
In this example and the comparative example, those having an etching factor of 2.5 or more were regarded as non-defective products, and those having an etching factor of less than 2.5 were regarded as defective products.

  If the etching factor is small, the verticality of the sidewalls in the wiring pattern is lost, and in the case of a fine wiring pattern with a narrow line width, there is a risk of short-circuiting or disconnection due to unmelted copper foil between adjacent wiring patterns. There is a risk of binding. In this test, the bottom width B and the top width T of the wiring pattern when the just etch position (the position of the resist end and the position of the bottom of the wiring pattern are aligned) are measured with a microscope, and the etching factor is measured. Was calculated. The results are shown in Table 3.

[Adhesion]
A resin substrate was bonded to the roughened surface of the copper foil to prepare a measurement sample. As the resin substrate, a commercially available polyphenylene ether-based resin (Ultra Low Transmission Loss Multilayer Substrate Material MEGRON6 manufactured by Panasonic Corporation) was used, the curing temperature at the time of bonding was 210 ° C., and the curing time was 2 hours.

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

[Handling: Wrinkle defect count]
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 bonding conditions are a temperature of 170 ° C., a pressure of 1.5 MPa, and a pressing time of 1 hour. 30 copper-clad laminates were prepared for each surface-treated copper foil, the copper foils were visually checked for wrinkles, and the number of copper-clad laminates with wrinkles in the copper foils (number of wrinkle defects) was counted. did. The handling property of the surface-treated copper foil was evaluated based on the number of defective wrinkles. When the number of wrinkle defects was 3 or less, it was accepted, and when it was 4 or more, it was rejected. The results are shown in Table 3.

[Vertical curvature arithmetic average Ssc, Rpm]
Using the BRUKER 3D white light interference microscope Wyko ContourGT-K, the surface shape of the roughened surface of the surface-treated copper foils of Examples 1 to 14 and Comparative Examples 1 to 5 was measured and subjected to shape analysis. The vertex curvature arithmetic averages Ssc and Rpm were obtained. The shape analysis was performed by the VSI measurement method using a high resolution CCD camera. The conditions are as follows: the light source is white light, the measurement magnification is 10 times, the measurement range is 477 μm × 357.8 μm, Lateral Sampling is 0.38 μm, speed is 1, Backscan is 10 μm, Length is 10 μm, Threshold is 3%, Terms Removal Data processing was performed after filtering (Cylinder and Tilt), Data Restore (Method: legacy, iterations 5), and Static Filter (Filter Size: 3, Filter Type: Median). The results are shown in Table 3.

[Grain distribution]
Using an EBSD (Electron Back Scatter Diffraction) camera Hikari / DC5.2 / A5.2 from TSL Solutions Inc. and a scanning electron microscope JSM-7001FA from JEOL Ltd. (JSM-7001FA) at a magnification of 5000 times and a beam step of 0.05 Under the conditions, the crystal grains of the roughened surface of the surface-treated copper foil were measured. In the measurement of crystal grains by EBSD, crystal grain boundaries having an orientation difference of 15 ° or more were used, and regions surrounded by the crystal grain boundaries were used as crystal grains.

At that time, the cut surface of the surface-treated copper foil was subjected to CP (cross section polisher) polishing, and the EBSD measurement was performed on the portion of the polished surface in the range shown in FIG. That is, when the foil thickness of the surface-treated copper foil is t, as shown in FIG. 2, the vertical (length in the thickness direction) 0.8 t and the horizontal (thickness direction) in contact with the surface opposite to the roughened surface. EBSD measurement was performed on a rectangular range of 1.6 t (length in the orthogonal direction). For example, when the foil thickness t is 10 μm, the rectangular range is 8.0 μm long and 16.0 μm wide, and when the foil thickness t is 6 μm, the rectangular range is 4.8 μm long and 9.6 μm wide, When the foil thickness t is 4 μm, the rectangular range is 3.2 μm long and 6.4 μm wide.
Based on the data of GRAIN SIZE of EBSD (electron beam backscatter diffraction method), the above-described crystal grain ratios R1, R2, and R3 were calculated. The results are shown in 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 the L & S Could not be made thin.
Since the bubbling flow rate of Comparative Example 2 was smaller than that of Example 3, the ratios R2 and R3 of the number of crystal grains were large, and the L & S could not be reduced.

In Comparative Example 3, since the bubbling flow rate was too large, the ratio R1 of the number of crystal grains was large, and the L & S could not be thinned.
In Comparative Example 4, compared with Example 1, since the reverse current was not applied with the pulse current of the roughening treatment and the roughened particles were not dissolved, the etching factor was lowered.
In Comparative Example 5, since the current for the roughening treatment was large, the coarsened particles became coarse, so that they remained easily during etching, and the etching factor was reduced.

101 Electrolytic copper foil 102 Cathode drum 104 Insoluble anode 105 Electrolyte

Claims (6)

A surface-treated copper foil having a roughened surface by a roughening treatment on the surface,
The foil thickness is 10 μm or less,
The vertex curvature arithmetic average Ssc of the roughened surface is 0.7 μm ⁻¹ or more and 3.8 μm ⁻¹ or less,
When the cross section is analyzed by electron beam backscatter diffraction after heating at 200 ° C. for 2 hours, among the crystal grains having a crystal grain size of 0.5 μm or more, the crystal grains having a crystal grain size of 0.5 μm or more and less than 1.0 μm The ratio R1 of the number of crystal grains is 0.51 or more and 0.97 or less, and the ratio R2 of the number of crystal grains having a crystal grain size of 1.0 to 3.0 μm is 0.03 or more and 0.42 or less. A surface-treated copper foil having a ratio R3 of the number of crystal grains having a grain size of 3.0 μm or more of 0.07 or less. Vertex curvature arithmetic average Ssc of the roughened surface is at 1.0 .mu.m ^-1 or 2.5 [mu] m ^-1 or less,
The surface-treated copper foil according to claim 1, wherein the ratio R1 is 0.59 or more and 0.96 or less, the ratio R2 is 0.04 or more and 0.41 or less, and the ratio R3 is 0.   The surface-treated copper foil according to claim 1 or 2, wherein 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 a tensile strength in a normal state is 400 MPa or more and 780 MPa or less, and a tensile strength measured at room temperature after heating at 220 ° C for 2 hours is 300 MPa or more.   A copper clad laminated board provided with the surface-treated copper foil as described in any one of Claims 1-4, and the resin-made board | substrate laminated | stacked on the roughening surface of this surface-treated copper foil.   A printed wiring board provided with the copper clad laminate according to claim 5.

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