JP6784806B2 - Copper foil with carrier foil and copper-clad laminate - Google Patents

Description

This application relates to copper foil with carrier foil. In particular, the present invention relates to a peelable type copper foil with a carrier foil, which can easily peel off the carrier foil even after receiving a high temperature load.

Conventionally, the applicant has proposed a copper foil with a carrier foil disclosed in Patent Document 1 and the like as a raw material for manufacturing a printed wiring board provided with a fine pitch circuit. The copper foil with a carrier foil disclosed in Patent Document 1 is a so-called peelable type copper foil with a carrier foil, and a bonding interface layer formed by using an organic agent is formed on the surface of the carrier foil, and the bonding thereof is performed. It is characterized in that an electrolytic copper foil layer is precipitated and formed on the interface layer. According to the copper foil with a carrier foil, the peel strength of the bonding interface layer can be maintained low and stabilized, so that the instability of the peel strength of the carrier foil after press molding is eliminated and the size is small. It becomes possible to peel off the carrier foil in a stable manner by force.

However, in recent years, in the printed wiring board manufacturing process, the press temperature at the time of bonding the copper foil with the carrier foil and the insulating layer constituent material tends to be higher. In particular, a temperature exceeding 300 ° C. may be loaded. In such a case, in the copper foil with a carrier foil disclosed in Patent Document 1, the metal of the carrier foil and the electrolytic copper foil diffuses from each other due to a high temperature load, so that the carrier foil and the electrolytic copper foil are connected to each other. Therefore, the carrier foil cannot be peeled off from the electrolytic copper foil.

Therefore, the applicant has described the carrier described in Patent Document 2 as a copper foil with a carrier foil capable of stably peeling off the carrier foil with a small force even when a temperature exceeding 300 ° C. is applied. We have proposed copper foil with foil. In the copper foil with a carrier disclosed in Patent Document 2, the carrier foil and the electrolytic copper foil are formed before heating and after heating in the range of 225 to 360 ° C. by forming a bonding interface layer using thiocyanic acid. The peeling strength at the bonding interface is 200 gf / cm or less. According to the copper foil with a carrier foil, the carrier foil can be removed more stably than the conventional peelable type copper foil with a carrier foil.

Further, in Patent Document 3, the applicant forms an organic bonding interface layer on the surface of the carrier foil by using an organic agent, and any one of nickel, nickel alloy, cobalt, and cobalt alloy is formed on the organic bonding interface layer. We have proposed a method for producing a copper foil with a carrier foil, which forms a dissimilar metal layer using the above and has an electrolytic copper foil layer on the dissimilar metal layer. The copper foil with a carrier foil obtained by this production method has a layer structure of "carrier foil / organic bonding interface layer / dissimilar metal layer such as nickel and cobalt / electrolytic copper foil layer". By providing the dissimilar metal layer in the copper foil with a carrier foil, it is possible to more stably prevent the carrier foil and the electrolytic copper foil from being connected to each other when a temperature exceeding 300 ° C. is applied.

Japanese Unexamined Patent Publication No. 2000-309898 Japanese Unexamined Patent Publication No. 2001-068804 Japanese Unexamined Patent Publication No. 2003-328178

However, when a temperature of 250 ° C. or higher is applied, the carrier foil of the copper foil with carrier foil is peeled off from the electrolytic copper foil even if the copper foil with carrier foil disclosed in Patent Documents 2 and 3 is applied. There was a large variation within the lot in the peeling strength (hereinafter, simply referred to as "carrier foil peeling strength"). When the carrier foil peeling strength of the copper foil with the carrier foil is increased in this way, the carrier foil and the electrolytic copper foil are connected as described above, and the carrier foil cannot be easily peeled off from the electrolytic copper foil. I was able to confirm the phenomenon.

FIG. 2 shows this situation. FIG. 2 shows a cross section of a conventional copper foil with a carrier foil after being heat-treated at 250 ° C. for 60 minutes. In the enlarged joint interface layer in the lower part of FIG. 2, a relatively large mutual diffusion site formed by a high temperature load can be confirmed. FIG. 3 schematically shows the situation at this time in an easy-to-understand manner. In FIG. 3, a mutual diffusion site formed by a high temperature load penetrating the bonding interface layer 4 between the carrier foil 2 and the copper foil 3 (hereinafter, simply referred to as “connecting portion 5”). Is shown. It has been found that when the connecting portion 5 is large and large, the carrier foil cannot be easily peeled off from the copper foil.

From the above, the present invention can easily peel off the carrier foil from the copper foil even when used for manufacturing a copper-clad laminate to which a temperature of 250 ° C. or higher is applied, and the carrier with little variation in lots. The purpose is to provide copper foil with foil.

Therefore, as a result of diligent research by the present inventors, the carrier foil and copper are provided with certain conditions described below in the copper foil with a carrier foil after being heat-treated at a temperature of 250 ° C. or higher. It was conceived that the formation of a connecting portion in the bonding interface layer between the foils was suppressed, and the carrier foil could be easily peeled off from the copper foil. Hereinafter, this technical idea will be described.

Copper foil with carrier foil: The copper foil with carrier foil according to the present application has a layer structure of carrier foil / bonding interface layer / copper foil layer, and the carrier foil is heat-treated at 250 ° C. for 60 minutes. After performing the heat treatment using an electrolytic copper foil having a tensile strength of 40 kgf / mm ² or more, the maximum connecting portion diameter of the connecting portion between the carrier foil and the copper foil layer existing in the bonding interface layer. Is 200 nm or less.

Copper-clad laminate: The copper-clad laminate according to the present application is characterized in that it is obtained by using the above-mentioned copper foil with a carrier foil.

Printed wiring board: The printed wiring board according to the present application is characterized in that it is obtained by using the above-mentioned copper foil with a carrier foil.

In the copper foil with a carrier foil according to the present application, the carrier foil can be easily peeled off from the electrolytic copper foil even when a temperature of 250 ° C. or higher is applied, and variations within the lot can be reduced. Therefore, it can be suitably used in the production of copper-clad laminates to which a temperature of 250 ° C. or higher is applied.

In Example 2, 250 ° C. x 60 minutes of a copper foil with a carrier foil using an electrolytic copper foil having a tensile strength of "40 kgf / mm ² or more after heat treatment at 250 ° C. x 60 minutes" as the carrier foil. It is a cross-sectional observation photograph after performing the heat treatment of. In the comparative example, 250 ° C. × 60 minutes of a copper foil with a carrier foil using an electrolytic copper foil having a tensile strength of “less than 40 kgf / mm ² after heat treatment at 250 ° C. × 60 minutes” as the carrier foil. It is a cross-sectional observation photograph after performing a heat treatment. FIG. 5 is a schematic cross-sectional view assuming a case where a copper foil with a carrier foil is heat-treated at 250 ° C. for 60 minutes and then has six connecting portions existing in a predetermined joining interface.

Hereinafter, the forms of the "copper foil with carrier foil" and the "copper-clad laminate" according to the present application will be described.

Form of Copper Foil with Carrier Foil: The copper foil with carrier foil according to the present application has a layer structure of a carrier foil / a bonding interface layer / a copper foil layer. The carrier foil is characterized in that an electrolytic copper foil having a tensile strength of 40 kgf / mm ² or more is used after heat treatment at 250 ° C. for 60 minutes. The heating condition of "250 ° C. x 60 minutes" corresponds to the heating condition generally adopted when manufacturing a copper-clad laminate by laminating a copper foil for a printed wiring board and an insulating layer constituent material such as a prepreg. To do.

If an electrolytic copper foil having a tensile strength of 40 kgf / mm ² or more after being heat-treated at 250 ° C. for 60 minutes is used as the carrier foil, it is heated by inhibiting the crystal growth of the carrier foil in the heating step. The diffusion of copper on the carrier foil side in the process can be slowed down, and the formation of a connecting portion can be prevented. As a result, there is no variation in the lot, and the peeling strength when peeling the carrier foil from the copper foil layer after heating is stably 200 gf / cm or less, preferably 50 gf / cm or less. On the other hand, if an electrolytic copper foil having a tensile strength of less than 40 kgf / mm ² after heat treatment at 250 ° C. for 60 minutes is used as the carrier foil, the connecting portion is formed depending on the lot, and copper is formed after heating. The peeling strength when peeling the carrier foil from the foil layer may exceed 200 gf / cm. Further, at the place where the connecting portion is formed, the copper foil layer may be torn and remain on the surface of the carrier foil. For these reasons, it is not preferable to use an electrolytic copper foil having a tensile strength of less than 40 kgf / mm ² as the carrier foil after the heat treatment under the above heating conditions because the peeling operation may become difficult. ..

The carrier foil according to the present application may have a tensile strength after heating under the above heating conditions within the above specific range, and the tensile strength of the carrier foil before heating is not particularly limited. As the carrier foil, an electrolytic copper foil coated with a metal component such as zinc or tin before heating can also be used. When an electrolytic copper foil coated with a metal component such as zinc or tin is heated at about 250 to 400 ° C., the coated metal component diffuses into the electrolytic copper foil and the crystal growth of the carrier foil in the heating step is hindered. , The mechanical strength before heating can be maintained. Therefore, such an electrolytic copper foil is also suitable as a carrier foil for the copper foil with a carrier foil according to the present application.

Further, it is preferable that the electrolytic copper foil has an average crystal grain size of less than 1.0 μm after being heat-treated at 250 ° C. for 60 minutes. There is a certain correlation between the crystal structure of the electrolytic copper foil and the tensile strength, and when the crystal grains constituting the crystal structure are fine, the tensile strength of the electrolytic copper foil shows a relatively high value. .. The electrolytic copper foil composed of fine crystal grains having an average crystal grain size of less than 1.0 μm exhibits a high tensile strength of about 40 kgf / mm ² or more. The average crystal grain size in the present application is obtained by EBSD analysis of image data showing the crystal state of the cross section of the electrolytic copper foil according to the EBSD method. An example of a specific measurement method will be described in the examples.

The copper foil with a carrier foil according to the present application preferably includes a connecting portion for connecting the carrier foil and the copper foil layer in the bonding interface layer, and the maximum connecting portion diameter thereof is 200 nm or less. If there is a portion where the maximum connecting portion diameter exceeds 200 nm, it may be difficult to peel off the carrier foil at that portion. If the carrier foil is forcibly peeled off, the copper foil will be peeled off at the connecting portion exceeding 200 nm. The layer is more likely to tear and remain on the surface of the carrier foil. However, in the copper foil with carrier foil according to the present application, the connecting portion is the bonding interface due to mutual diffusion of copper between the carrier foil and the copper foil layer when heated under the above heating conditions and the like. The mutual diffusion site that penetrates the layer and connects the carrier foil and the copper foil layer is shown.

Further, the copper foil with carrier foil according to the present application exists in the bonding interface layer corresponding to 2000 nm when the direction orthogonal to the thickness direction of the copper foil with carrier foil is defined as the length direction as described above. It is preferable that the total length of the connecting portion is 500 nm or less. The total length of the connecting portions corresponds to the total length of each connecting portion diameter of each connecting portion existing in the bonding interface layer having a width of 2000 nm. If the total length of the connecting portion exceeds 500 nm, mutual diffusion due to heating occurs excessively, which may make it difficult to peel off the carrier foil, which is not preferable.

The copper foil with a carrier foil according to the present application has a bonding interface corresponding to a length of 2000 nm in the cross section of the bonding interface layer after the copper foil with a carrier foil is heat-treated at 250 ° C. for 60 minutes. The average connecting portion diameter existing in the layer is preferably 50 nm or less. If the average connecting portion diameter exceeds 50 nm, the peeling strength when peeling the carrier foil from the copper foil layer may exceed 200 gf / cm, so that the copper foil layer is torn and remains on the surface of the carrier foil. It is not preferable because it becomes. Here, reference numeral 5 in FIG. 3 indicates a “connecting portion” formed by diffusion of copper generated between the carrier foil 2 and the copper foil layer 3 by heating, and reference numeral 5 is shown in FIG. "R2, R3, R4, R5, R6" indicates the "connecting portion diameter". The "average connecting portion diameter" in the case of FIG. 3 is the value obtained by dividing the sum value of the six connecting portion diameters R1, R2, R3, R4, R5, and R6 by 6.

The bonded interface layer of the copper foil with a carrier foil according to the present application described above preferably has a thickness of 5 nm to 60 nm. If the thickness of the bonding interface layer is less than 5 nm, the distance between the carrier foil and the copper foil layer becomes too close, and the diffusion of copper that occurs between the carrier foil and the copper foil layer becomes easy, which is not preferable. On the other hand, if the thickness of the bonding interface layer exceeds 60 nm, it becomes unstable for the carrier foil to hold the copper foil layer, which is not preferable. The bonded interface layer is more preferably 5 nm to 30 nm in thickness. When the thickness of the bonding interface layer is 30 nm or less, the variation in the thickness of the bonding interface layer is small, and the distribution of the connecting portions formed in the bonding interface by heating becomes extremely uniform. Therefore, the copper foil layer to the carrier foil This is because the peeling strength at the time of peeling is stable.

The bonding interface layer of the copper foil with a carrier foil according to the present application includes an "organic bonding interface layer" formed by using an organic component and an "inorganic bonding interface layer" formed by using an inorganic component.

When the "organic bonding interface layer" is adopted, a compound containing at least one or more of compounds selected from the group consisting of nitrogen-containing organic compounds, sulfur-containing organic compounds and carboxylic acids should be used as organic components. Is preferable. The nitrogen-containing organic compound referred to here includes a nitrogen-containing organic compound having a substituent. Specifically, as the nitrogen-containing organic compound, 1,2,3-benzotriazole, carboxybenzotriazole, N', N'-bis (benzotriazolylmethyl) urea, 1H, which are triazole compounds having a substituent, are used. It is preferable to use -1,2,4-triazole, 3-amino-1H-1,2,4-triazole and the like. As the sulfur-containing organic compound, it is preferable to use mercaptobenzothiazole, thiothianulic acid, 2-benzimidazole thiol and the like. Further, as the carboxylic acid, it is preferable to use a monocarboxylic acid, and among them, oleic acid, linoleic acid, linoleic acid and the like are preferably used. This is because these organic components have excellent high-temperature heat resistance, and it is easy to form a bonded interface layer having a thickness of 5 nm to 60 nm on the surface of the carrier foil.

When the "inorganic bonding interface layer" is adopted, it is selected from the group consisting of Ni, Mo, Co, Cr, Fe, Ti, W, P or an alloy or compound containing these as main components as the inorganic component. It is possible to use at least one or more of the following. In the case of these inorganic bonded interface layers, it is possible to form them by using a known method such as a wet film forming method such as an electrolytic plating method or a non-electrolytic plating method, or a dry film forming method such as a sputtering method or a vapor deposition method. is there.

The copper foil with a carrier foil according to the present application described above has a layer structure of a carrier foil / a bonding interface layer / a copper foil layer. In order to enable the carrier foil to be stably peeled off from the copper foil layer after heating, it is necessary to suppress the diffusion of copper between the carrier foil and the copper foil layer via the bonding interface layer as described above. In order to more effectively suppress the diffusion behavior of copper, the copper foil with a carrier foil according to the present application is provided with a heat-resistant metal layer between the carrier foil and the copper foil layer in order to suppress the diffusion of copper due to heating. Is preferable. Specifically, the copper foil with carrier foil according to the present application includes "carrier foil / bonding interface layer / heat-resistant metal layer / copper foil layer", "carrier foil / heat-resistant metal layer / bonding interface layer / copper foil layer", etc. It is preferable to have a layer structure of.

In consideration of heat resistance stability, this heat-resistant metal layer is composed of nickel, nickel-phosphorus, nickel-chromium, nickel-molybdenum, nickel-molybdenum-cobalt, nickel-cobalt, nickel-tungsten, nickel-tin-phosphorus. It is possible to use a nickel alloy such as cobalt, cobalt-phosphorus, cobalt-molybdenum, cobalt-tungsten, cobalt-copper, cobalt-nickel-phosphorus, cobalt-tin-phosphorus, etc. preferable. This heat-resistant metal layer can be formed by using a known method such as a wet film forming method such as an electrolytic plating method or a electroless plating method, or a dry film forming method such as a sputtering method or a vapor deposition method. The thickness of the heat-resistant metal layer is preferably 1 nm to 50 nm.

In the copper foil with a carrier foil according to the present application, there is no particular limitation on the thickness of the carrier foil, and it is sufficient to consider it as a thickness of 9 μm to 200 μm that can function as a carrier foil. Further, the thickness of the copper foil layer is not particularly limited, but it may be considered as a thin copper foil that requires a carrier foil, and may be considered as a thickness of about 0.1 μm to 18 μm.

The copper foil with a carrier foil described above uses "an electrolytic copper foil having a tensile strength of 40 kgf / mm ² or more after being heat-treated at 250 ° C. for 60 minutes" as the carrier foil, and is used as the carrier foil / bonded. The layer structure of the interface layer / copper foil layer may be provided, and the copper foil constituting the copper foil layer is not particularly limited, and the manufacturing method thereof is also not limited. For example, the copper foil layer may be a copper layer formed by a wet film forming method such as an electrolytic plating method or a electroless plating method, or may be formed by a dry film forming method such as a sputtering method or a vapor deposition method. It may be a copper layer, or a copper foil layer may be formed by a plurality of copper layers having different manufacturing methods by appropriately using these manufacturing methods in combination. However, the copper layer formed by the wet film forming method is preferable because the production cost is lower than that of the dry film forming method. Further, as compared with the electroless plating method, the electrolytic copper foil layer is formed by the electrolytic plating method from the viewpoint that a copper layer having a predetermined thickness can be formed at a speed commensurate with the industrial production speed. Is preferable. The electrolytic copper foil has a crystal structure suitable for etching, and is suitable for use as a circuit forming layer for a printed wiring board or the like. When the copper foil layer is formed by the electrolytic plating method, the copper foil with a carrier foil according to the present application can be produced, for example, by the production method disclosed in Patent Document 1 described above. That is, the surface of the carrier foil is cleaned by pickling or the like, a bonded interface layer is formed on the surface of the cleaned carrier foil, a copper foil layer is formed on the bonded interface layer, and the copper foil is formed as necessary. The surface of the layer can be roughened, rust-proofed, silane coupling agent-treated, etc., and dried.

The copper foil with a carrier foil according to the present application can be used when manufacturing a copper-clad laminate and a printed wiring board, which will be described later. Further, when manufacturing a coreless build-up multilayer printed wiring board, the copper foil with a carrier foil can be used as a support substrate. Specifically, a build-up layer having a required number of layers is formed on the surface of a support substrate in which the copper foil with a carrier foil and a prepreg or the like are laminated by a build-up method. Then, the carrier foil and the copper foil layer are peeled off at the bonding interface layer of the copper foil with the carrier foil to separate the build-up layer. Through such a process, a coreless build-up multilayer printed wiring board can be obtained. If the copper foil with a carrier foil is used as a support substrate, even if the insulating layer is laminated on the copper foil with a carrier foil and heated at a temperature of 250 ° C. or higher, as described above, the copper foil is transferred from the carrier foil to the copper foil. The diffusion of copper into the layer is slow, and the formation of the connecting portion can be suppressed. Therefore, when the carrier foil and the copper foil layer are peeled off, the carrier foil can be stably peeled off. Therefore, after the build-up layer is formed, when the carrier foil and the copper foil layer are peeled off, problems such as the copper foil layer remaining on the carrier foil side do not occur, and a decrease in yield can be suppressed. Further, as described above, the copper foil with a carrier foil according to the present application has a high tensile strength of the carrier foil, so that it can satisfy the mechanical strength required for the support substrate and prevent the support substrate from warping. Can be easily handled with. Further, even if the thickness of the carrier foil of the copper foil with the carrier foil is thin, the mechanical strength required for the support substrate can be satisfied, so that the thickness of the carrier foil is prevented in order to prevent the support substrate from warping. It is not necessary to increase the thickness, and wasteful consumption of resources can be suppressed.

Copper-clad laminate: The copper-clad laminate according to the present application is a laminate of the above-mentioned copper foil with carrier foil and the insulating layer constituent material according to the present application, and is a rigid copper-clad laminate and a flexible copper-clad laminate. Including both. That is, there is no particular limitation on the type of the insulating layer constituent material referred to here. If the copper foil with a carrier foil according to the present application is used, the carrier foil is stable because the connecting portion is difficult to form as described above even if the copper foil with the carrier foil is used, even if it is heated at a temperature of 250 ° C. or higher when it is attached to the insulating layer constituent material. Can be peeled off. Further, even if the thickness of the carrier foil is thin, it has sufficient mechanical strength, so that when handling the copper-clad laminate, problems such as warping of the copper-clad laminate are unlikely to occur, and handling becomes easy. ..

Printed wiring board: The printed wiring board according to the present application is obtained by using the above-mentioned copper foil with carrier foil according to the present application, and both a rigid type printed wiring board and a flexible type printed wiring board can be used. Including. In addition, the printed wiring board according to the present application includes all printed wiring boards such as single-sided printed wiring boards, double-sided printed wiring boards, and multi-layer printed wiring boards.

Manufacture of carrier foil: A current density of 60 A / dm ² using a sulfuric acid-based copper electrolytic solution having a copper concentration of 80 g / L, a free sulfuric acid concentration of 250 g / L, a chlorine concentration of 2 mg / L, a gelatin concentration of 2 mg / L, and a liquid temperature of 50 ° C. To produce an electrolytic copper foil having a thickness of 18 μm, which was used as a carrier foil. At this time, the normal tensile strength of the electrolytic copper foil was 43.8 kgf / mm ² , and the tensile strength after heat treatment at 250 ° C. for 60 minutes was 42.2 kgf / mm ² . The normal state of the carrier foil and the measurement of the tensile strength after heating were performed in accordance with IPC-TM-650. The same applies to the following examples and comparative examples.

Formation of bonded interface layer: A bonded interface layer was formed on the surface of the carrier foil as follows. The carrier foil is immersed in an organic agent-containing dilute sulfuric acid aqueous solution having 150 g / L sulfuric acid, 10 g / L copper concentration, 800 mg / L carboxybenzotriazole (CBTA) concentration, and a liquid temperature of 30 ° C. for 30 seconds to remove the contaminating components attached to the carrier foil. While removing by pickling, CBTA was adsorbed on the surface of the carrier foil to form a bonding interface layer made of CBTA on the surface of the carrier foil to obtain a "carrier foil having a bonding interface layer".

Formation of copper foil layer: Next, in a copper electrolytic solution, a "carrier foil having a bonding interface layer" is cathode polarized, and a copper foil layer is formed on the surface of the bonding interface layer to obtain a copper foil with a carrier foil. It was. The copper foil layer is formed by electrolyzing a copper sulfate solution having a copper concentration of 70 g / L, a free sulfuric acid concentration of 150 g / L, and a liquid temperature of 45 ° C. at a current density of 30 A / dm ² and having a thickness of 3 μm. Was formed.

Surface treatment of copper foil layer: A zinc-nickel alloy rust preventive layer is formed on the surface of the copper foil layer of the copper foil with carrier foil obtained above without roughening treatment, and electrolytic chromate treatment and amino-based treatment are performed. A silane coupling agent treatment was applied to obtain a surface-treated copper foil with a carrier foil.

Measurement of average grain: For the measurement of the crystal grain size of the carrier foil, an FE gun-type scanning electron microscope (SUPRA 55VP, manufactured by Karl Zeiss Co., Ltd.) equipped with an EBSD evaluation device (OIM Analysis, manufactured by TSL Solutions Co., Ltd.) ) And the attached EBSD analyzer were used. Using this device, image data of the crystalline state of the cross section of the copper foil was obtained for the sample whose cross section was appropriately processed according to the EBSD method, and this image data was used as an EBSD analysis program (OIM Analysis, Inc.). The average crystal grain size was quantified in the analysis menu of (manufactured by TSL Solutions). In this evaluation, an orientation difference of 5 ° or more was regarded as a grain boundary. The conditions of the scanning electron microscope at the time of observation were an accelerating voltage of 20 kV, an aperture diameter of 60 mm, a high current mode, and a sample angle of 70 °. The measurement results are summarized in Table 1.

Measurement of peeling strength: The peeling strength of the carrier foil under normal conditions and after heating was performed in accordance with IPC-TM-650. At the time of measurement, a plate-shaped test piece prepared by the following method was used. First, an insulating resin layer constituent material was bonded to the surface of the copper foil layer of the above-mentioned copper foil with a carrier foil using an adhesive to prepare a copper-clad laminate. At this time, a cured prepreg having a thickness of 100 μm was used as the insulating layer constituent material. Then, the carrier foil on the surface of the copper-clad laminate was cut to prepare a plate-shaped test piece having a width of 10 mm and a length of 10 cm. When preparing a sample for measuring the normal peeling strength, a copper foil with a carrier foil before the heat treatment is used, and when preparing a sample for measuring the peeling strength after heating, the temperature is 250 ° C. in advance. A copper foil with a carrier foil that had been heat-treated for 60 minutes was used. The peeling strength of the carrier foil after heating was measured from five different locations of the copper foil with the carrier foil, and the range of the measured values was shown five times. The measurement results are summarized in Table 1.

Measurement of connecting portion diameter: Based on the image data of the crystalline state of the cross section of the copper foil used for measuring the average crystal grains, the copper foil with the carrier foil obtained above was heat-treated at 250 ° C. for 60 minutes. In the cross section of the later bonded interface layer, the diameter of the connecting portion existing in the bonded interface layer corresponding to the length of 2000 nm was obtained in the same manner as the method schematically shown in FIG. 3, and the average connecting portion diameter and the connecting portion were found. The total length and the maximum connecting diameter were calculated. The measurement results are summarized in Table 1.

The only difference between the second embodiment and the "formation of the bonding interface layer" and the "formation of the copper foil layer" of the first embodiment is that the step of "formation of the heat-resistant metal layer" is provided. Therefore, only "formation of heat-resistant metal layer" will be described.

Formation of heat-resistant metal layer: Next, a nickel layer was formed as a heat-resistant metal layer on the surface of the bonding interface layer. The formation of the refractory metal layer, a nickel electrolyte, nickel sulfate _{(NiSO 4 · 6H 2 O)} 330g / L, nickel chloride _{(NiCl 2 · 6H 2 O)} 45g / L, boric acid 35 g / L, liquid temperature 45 A nickel layer having a conversion thickness of 10 nm was formed by electrolysis at a current density of 2.5 A / dm ² using a watt bath at ° C. and pH 3.

Hereinafter, as in Example 1, a copper foil layer is formed on the surface of the "carrier foil provided with the heat-resistant metal layer and the bonding interface layer" on which the heat-resistant metal layer and the bonding interface layer exist, and the surface of the copper foil layer is surfaced. Treatment was performed to obtain a copper foil with a carrier foil. FIG. 1 shows a cross-sectional observation photograph of the electrolytic copper foil with a carrier foil obtained in Example 2.

The third embodiment is different from the first embodiment only in the carrier foil. Therefore, only the production of a carrier foil different from that of Example 1 will be described.

Manufacture of carrier foil: Copper concentration 80 g / L, free sulfuric acid concentration 140 g / L, chlorine concentration 0.25 mg / L, iodine concentration 5.0 mg / L using potassium iodide (KI), sulfuric acid system with solution temperature 50 ° C. An electrolytic copper foil having a thickness of 18 μm was produced by electrolysis at a current density of 75 A / dm ² using a copper electrolytic solution, and this was used as a carrier foil. Tensile strength of normal electrodeposited copper foil in this case the tensile strength after the heat treatment of ^{48.7kgf / mm 2, 250 ℃ ×} 60 minutes was 45.0kgf / mm ^2.

The fourth embodiment differs from the first embodiment only in the carrier foil. Therefore, only the production of a carrier foil different from that of Example 1 will be described.

Manufacture of carrier foil: Current density using a sulfuric acid-based copper electrolytic solution having a copper concentration of 80 g / L, a sulfuric acid concentration of 140 g / L, a molecular weight of 10000 polyethyleneimine 53 mg / L, a chlorine concentration of 2.2 mg / L, and a liquid temperature of 50 ° C. Electrolysis was performed at 70 A / dm ² to produce an electrolytic copper foil having a thickness of 18 μm, which was used as a carrier foil. At this time, the normal tensile strength of the electrolytic copper foil was 62.2 kgf / mm ² , and the tensile strength after heat treatment at 250 ° C. for 60 minutes was 48.1 kgf / mm ² .

Example 5 differs from Example 1 only in the carrier foil. Therefore, only the production of a carrier foil different from that of Example 1 will be described.

Production of carrier foil: In Example 5, a sulfuric acid acidic copper electrolytic solution having a copper concentration of 80 g / L, a sulfuric acid concentration of 140 g / L, a molecular weight of 10000 polyethyleneimine 100 mg / L, a chlorine concentration of 1.0 mg / L, and a liquid temperature of 50 ° C. was used. It was electrolyzed at a current density of 70 A / dm ² to produce an electrolytic copper foil having a thickness of 18 μm, which was used as a carrier foil. At this time, the normal tensile strength of the electrolytic copper foil was 79.0 kgf / mm ² , and the tensile strength after heat treatment at 250 ° C. for 60 minutes was 55.4 kgf / mm ² .

Comparative example

In the comparative example, instead of the electrolytic copper foil used as the carrier foil in Example 1, the normal tensile strength is 40.3 kgf / mm ² , and the tensile strength after heat treatment at 250 ° C. × 60 minutes is An electrolytic copper foil of 35.0 kgf / mm ² was used as the carrier foil. Regarding other steps, a copper foil with a carrier foil was obtained as a comparative example in the same manner as in Example 2. Then, the average crystal grains of the carrier foil, the peeling strength of the carrier foil, and the diameter of the connecting portion were measured in the same manner as in Examples. The measurement results are summarized in Table 1. Further, FIG. 1 shows a cross-sectional observation photograph of the electrolytic copper foil with a carrier foil obtained in the comparative example.

[Comparison between Examples and Comparative Examples]

As can be understood from Table 1, with reference to Examples 1 to 5, "an electrolytic copper foil having a tensile strength of 40 kgf / mm ² or more after being heat-treated at 250 ° C. for 60 minutes" as a carrier foil. Is used. On the other hand, the comparative example has only a tensile strength of 35.0 kgf / mm ² after being heat-treated at 250 ° C. for 60 minutes. As a result, with respect to Examples 1 to 5, "the maximum connecting portion diameter of the connecting portions existing in the bonding interface layer is 200 nm or less" and "the connection existing in the bonding interface layer corresponding to the length of 2000 nm". The total length of the part is 500 nm or less. " However, in the case of the comparative example, the maximum connecting portion diameter exceeds 200 nm, and the total length of the connecting portion also exceeds 500 nm. Therefore, it can be understood that the peeling strength and variation of the carrier foil of the comparative example are extremely high values as compared with the examples. In the case of the peeling strength of the carrier foil at the level of this comparative example, it may be difficult to peel off the carrier foil due to these variations.

In the copper foil with carrier foil according to the present application, the carrier foil can be easily peeled off from the electrolytic copper foil even when a temperature of 250 ° C. or higher is applied, so that copper to which a temperature of 250 ° C. or higher is applied. It can be suitably used in the production of stretched laminates. Since the peeling strength when peeling the carrier foil from the copper foil layer is stable at a low level, the carrier foil can be easily peeled off.

1 Copper foil with carrier foil 2 Carrier foil 3 Copper foil layer 4 Bonding interface layer 5 Connecting part

Claims (9)

A copper foil with a carrier foil having a layer structure of a carrier foil / a bonding interface layer / a copper foil layer.
As the carrier foil, an electrolytic copper foil having a tensile strength of 40 kgf / mm ² or more after being heat-treated at 250 ° C. for 60 minutes was used.
A copper foil with a carrier foil, characterized in that the maximum connecting portion diameter of the connecting portion between the carrier foil and the copper foil layer existing in the bonding interface layer after the heat treatment is 200 nm or less. Claim 1 in which the total length of the connecting portion existing in the bonding interface layer corresponding to the length of 2000 nm is 500 nm or less when the direction orthogonal to the thickness direction of the copper foil with the carrier foil is defined as the length direction. Copper foil with carrier foil as described in. The copper foil with a carrier foil according to claim 1 or 2, wherein the bonding interface layer has a thickness of 5 nm to 60 nm. The copper foil with a carrier foil according to any one of claims 1 to 3, wherein the bonding interface layer is formed by using an organic component. The copper foil with a carrier foil according to claim 4, wherein the organic component of the bonding interface layer contains at least one compound selected from the group consisting of a nitrogen-containing compound, a sulfur-containing compound, and a carboxylic acid. The copper foil with a carrier foil according to any one of claims 1 to 3, wherein the bonding interface layer is formed by using an inorganic component. The claim that the inorganic component of the bonding interface layer contains at least one selected from the group consisting of Ni, Mo, Co, Cr, Fe, Ti, W, P, or alloys or compounds containing these as main components. 6. The copper foil with a carrier foil according to 6. The copper foil with a carrier foil according to any one of claims 1 to 7, wherein a heat-resistant metal layer is provided between the carrier foil and the copper foil layer constituting the copper foil with a carrier foil. A copper-clad laminate obtained by using the copper foil with a carrier foil according to any one of claims 1 to 8.

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