Double-sided copper-clad laminated film, printed circuit board comprising same, and method for manufacturing double-sided copper-clad laminated film

Abstract

Disclosed are a double-sided copper-clad laminated film, a printed circuit board comprising same, and a method for manufacturing the double-sided copper-clad laminated film. The double-sided copper clad laminated film comprises: a polyimide-based substrate having a thickness of 10 ㎛ (exclusive) to 30 ㎛; a first nickel layer disposed on a first surface of the polyimide-based substrate; a first copper layer disposed on a surface of the first nickel layer opposite to the first surface of the polyimide-based substrate; a second nickel layer disposed on a second surface of the polyimide-based substrate; and a second copper layer disposed on a surface of the second nickel layer opposite to the second surface of the polyimide-based substrate, wherein the thickness of the first copper layer or the second copper layer is 10% to 25% (exclusive) based on the thickness of the polyimide-based substrate, and when the surface of the first copper layer or the second copper layer is etched with an etching solution containing ferric chloride, chromium is not detected by energy dispersive spectroscopy (EDAX) or electron probe microanalysis (EPMA), and the height of curls on the film surface may be less than 0.1 mm.

Description

Double-sided copper-clad laminate film, printed circuit board including the same, and method for manufacturing the double-sided copper-clad laminate film

[0001] The present invention relates to a double-sided copper-clad laminate film, a printed circuit board including the same, and a method for manufacturing the double-sided copper-clad laminate film.

[0002] With the advancement of semiconductor integrated circuits, electronic products are accelerating toward miniaturization, weight reduction, thinner designs, higher density, and greater flexibility. This trend is driving demand for materials that achieve high integration for various electronic devices.

[0003] For example, a printed circuit board (PCB) is a structure in which both the upper and lower surfaces of an insulating substrate film are bonded with copper foil to form a circuit. This structure can form lands (solderable points) on both the upper and lower surfaces. Therefore, when components are mounted, the component density can be increased within the same size. Typically, printed circuit boards can be manufactured using a casting method in which a molten polymer film substrate is coated on copper foil; a method in which one side of a substrate film is sputtered and then electroplated; and a laminating method in which copper foil and a thermosetting substrate film are thermally bonded. However, even with the above methods, problems such as thermal shock, film folding, wrinkles, or curling occur during the manufacturing process of a copper-clad laminate using an ultra-thin film substrate applied to a printed circuit board.

[0004] Accordingly, there is a need for a copper-clad laminate film using an ultra-thin film substrate that is easy to etch because it does not cause folding, wrinkles, or curling of the film even when it goes through a high-temperature manufacturing process, has excellent peel strength and flexibility, and does not detect chromium components after acid etching, and thus is easy to etch, a flexible printed circuit board including the same, and a method for manufacturing the double-sided copper-clad laminate film.

[0005] One aspect is to provide a double-sided copper-clad laminate film that is easy to etch because it does not cause folding, wrinkling, or curling of the film, has excellent peel strength and flexibility, and does not detect chromium components after acid etching.

[0006] Another aspect is to provide a printed circuit board including the above copper foil laminate film.

[0007] Another aspect is to provide a method for manufacturing the double-sided copper-clad laminate film.

[0008] According to one aspect,

[0009] A polyimide-based substrate having a thickness of more than 10 ㎛ to 30 ㎛;

[0010] A first nickel layer located on the first surface of the polyimide-based substrate;

[0011] A first copper layer located on a surface of the first nickel layer opposite to the first surface of the polyimide-based substrate;

[0012] A second nickel layer located on the second surface of the polyimide-based substrate; and

[0013] A second copper layer located on a surface of the second nickel layer opposite to the second surface of the polyimide-based substrate;

[0014] The thickness of the first copper layer or the second copper layer is less than 10% to 25% based on the thickness of the polyimide-based substrate,

[0015] When etching the surface of the first copper layer or the second copper layer with an etching solution containing ferric chloride, chromium is not detected by EDAX (Energy Dispersive Spectroscopy) or EPMA (Electron Probe MicroAnalysis).

[0016] A double-sided copper-clad laminate film is provided, wherein the height of the curl on the film surface is less than 0.1 mm.

[0017] The thickness of the first nickel layer or the second nickel layer may be 3 nm to 10 nm.

[0018] The first copper layer and the second copper layer may each include a copper sputter layer and an electrolytic copper plating layer.

[0019] The peel strength according to the following equation 1 can be satisfied:

[0020] [Formula 1]

[0021] 0.3 ≤ |P1 - P2| ≤ 0.5

[0022] Among the foods,

[0023] P1 is the peel strength (kgf / in) of the first copper layer or the second copper layer on the polyimide-based substrate measured at a speed of 50 mm / min and an angle of 180° after the film has been left at room temperature for 4 hours,

[0024] P2 is the peel strength (kgf / in) of the first copper layer or the second copper layer on the polyimide-based substrate, measured at a speed of 50 mm / min and an angle of 180° after the film was heat-treated at 150°C for 2 hours, left at room temperature for 30 minutes twice, and further heat-treated at 240°C for 10 minutes.

[0025] Fatigue life by MIT measurement according to JIS C 6471 can be more than 200,000 cycles.

[0026] Depending on other aspects,

[0027] A printed circuit board including the aforementioned copper-clad laminate film is provided.

[0028] According to another aspect,

[0029] A step of providing a polyimide-based substrate having a thickness of more than 10 ㎛ to 30 ㎛;

[0030] A step of sequentially forming a first nickel layer and a first copper layer on the first surface of the polyimide-based substrate; and

[0031] A step of manufacturing a double-sided copper-clad laminate film by sequentially forming a second nickel layer and a second copper layer on the second surface of the polyimide-based substrate;

[0032] The thickness of the first copper layer or the second copper layer is less than 10% to 25% based on the thickness of the polyimide-based substrate,

[0033] When etching the surface of the first copper layer or the second copper layer with an etching solution containing ferric chloride, chromium is not detected by EDAX (Energy Dispersive Spectroscopy) or EPMA (Electron Probe MicroAnalysis).

[0034] A method for manufacturing a double-sided copper-clad laminate film having a curl height of less than 0.1 mm on the film surface is provided.

[0035] The step of providing the above polyimide-based substrate may be to provide the polyimide-based substrate using a roll-to-roll process that can be controlled so that the ends and the center of the roll have different tensions.

[0036] A double-sided copper-clad laminate film and a printed circuit board including the same according to one aspect are films using an ultra-thin film substrate, and even when subjected to a high-temperature manufacturing process, the film does not fold, wrinkle, or curl, and has excellent peel strength and flexibility, and no chromium component is detected after acid etching, making etching easy. The method for manufacturing a double-sided copper-clad laminate film can improve process contamination even when subjected to a high-temperature manufacturing process.

[0037] Figure 1 is a cross-sectional schematic diagram of a double-sided copper-clad laminate film according to one embodiment.

[0038] Figure 2 is a photograph showing the measurement of the curl height of a double-sided copper-clad laminate film manufactured according to Example 1.

[0039] Figure 3 is a photograph showing the measured curl height of a double-sided copper-clad laminate film manufactured by Comparative Example 1.

[0040] Hereinafter, with reference to examples and drawings of the present invention, a double-sided copper-clad laminate film, a printed circuit board including the same, and a method for manufacturing the double-sided copper-clad laminate film will be described in detail. These examples are provided solely as examples to more specifically explain the present invention, and it will be apparent to those skilled in the art that the scope of the present invention is not limited by these examples.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. In case of conflict, the present specification, including its definitions, shall prevail.

[0042] Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, suitable methods and materials are described herein.

[0043] The term "including" in this specification means that other components may be included rather than excluding other components unless specifically stated to the contrary.

[0044] The term "combination of these" in this specification means a mixture or combination of one or more of the described components.

[0045] As used herein, the term "and / or" is meant to include any and all combinations of one or more of the items described herein. As used herein, the term "or" means "and / or." The expressions "at least one" or "one or more" preceding elements herein may modify the entire list of elements and do not mean that they modify individual elements described above.

[0046] When a component is referred to herein as being "on" or "over" another component, the component may be directly on the other component, or there may be intervening components between the components. Conversely, when a component is referred to as being "directly on" or "over" another component, there may not be intervening components.

[0047] In this specification, “~-based polymer (resin)” or “~-based copolymer (resin)” is a broad concept that includes all of “~ polymer (resin)”, “~ copolymer (resin)”, or / and “~ polymer (resin) or copolymer (resin) derivatives”.

[0048] In this specification, "polyimide" means a polymer containing a repeating structural unit including an imide group. "Polyimide system" is a concept that includes both polyimide and polymers containing a repeating structural unit including an amide group in addition to an imide group. Examples of polymers containing a repeating structural unit including both an imide group and an amide group include polyamideimide.

[0049] One method for manufacturing printed circuit boards (PCBs) involves sputtering one side of a substrate layer and then electroplating. However, this method can cause problems such as thermal shock during high-temperature processing, film folding, wrinkling, or detection of chromium components after acid etching when using an ultra-thin film substrate.

[0050] To solve these problems, a copper-clad laminate film and a manufacturing method thereof are known that attach an adhesive protective film to the back of an ultra-thin film substrate and then de-laminate it to address thermal shock, film folding, wrinkling, or curling during high-temperature sputtering and electroplating processes. However, since most of these technologies use a roll-to-roll process for the Chip on Film (COF) process used in driver integrated circuits (ICs), curling occurs when processed into sheets used in the production of flexible printed circuit boards (FPCBs) or camera coils. To address the curling problem, a technology has been used that performs sputtering and electroplating on one side of the substrate, attaches a protective film, and then de-lamines the protective film. However, this technology suffers from contamination during the attachment and de-laminating of the protective film, and it is difficult to completely resolve issues such as curling, bending, and easy etching.

[0051] Taking these points into consideration, the inventors of the present invention propose a novel double-sided copper-clad laminate film, a printed circuit board including the same, and a method for manufacturing the double-sided copper-clad laminate film.

[0052] Figure 1 is a cross-sectional schematic diagram of a double-sided copper-clad laminate film according to one embodiment.

[0053] Referring to FIG. 1, a double-sided copper-clad laminate film (480) according to one embodiment has a structure in which a first nickel layer (410) or a second nickel layer (430) is disposed on both sides of a polyimide-based substrate (420), and a first copper layer (400) or a second copper layer (440) is disposed on the first nickel layer (410) or the second nickel layer (430).

[0054] Specifically, a double-sided copper-clad laminate film according to one embodiment comprises: a polyimide-based substrate having a thickness of more than 10 ㎛ to 30 ㎛; a first nickel layer located on a first side of the polyimide-based substrate; a first copper layer located on a side of the first nickel layer opposite the first side of the polyimide-based substrate; a second nickel layer located on a second side of the polyimide-based substrate; And a second copper layer located on a surface of the second nickel layer opposite to the second surface of the polyimide-based substrate; wherein the thickness of the first copper layer or the second copper layer is less than 10% to 25% based on the thickness of the polyimide-based substrate, and when etching the surface of the first copper layer or the second copper layer with an etchant containing ferric chloride, chromium is not detected by EDAX (Energy Dispersive Spectroscopy) or EPMA (Electron Probe MicroAnalysis), and the height of curl on the film surface may be less than 0.1 mm. The double-sided copper-clad laminate film is a film using a polyimide-based substrate having a thickness of more than 10 ㎛ to 30 ㎛, and can provide a film that is easy to etch as it does not fold or wrinkle even when going through a high-temperature manufacturing process, has excellent peel strength and flexibility, and no chromium component is detected after acid etching.

[0055] The polyimide-based substrate may be a polyimide film or a low-k polyimide (modified polyimide) film. The polyimide film used as the substrate may be manufactured by extruding polyamic acid, a polyimide precursor, into a film, and then heat-treating and drying the film to imidize the polyamic acid. Moisture and residual gases may be removed through a drying process commonly used in the art. For example, the drying may be performed through a roll-to-roll type heat treatment under atmospheric pressure or using an infrared (IR) heater in a vacuum atmosphere.

[0056] The glass transition temperature (Tg) of the above polyimide-based substrate may be 200°C or higher. The substrate may have sufficient heat resistance, so that no physical or chemical changes may occur within a high temperature range and for a long period of time. If the glass transition temperature (Tg) of the polyimide-based substrate is 200°C or lower, the substrate may melt during the printed circuit board manufacturing process or the substrate may undergo dimensional changes after a high-temperature process, resulting in warping of the circuit board.

[0057] The thickness of the polyimide-based substrate may be greater than 10 μm to 30 μm. For example, the thickness of the substrate may be 11 μm to 28 μm, 12 μm to 26 μm, or 12.5 μm to 25 μm. A copper-clad laminate film including a substrate having such a thickness is suitable for use in electronic devices requiring fine patterns, such as flexible printed circuit boards (FPCBs) and / or camera coils.

[0058] If necessary, the polyimide-based substrate may be subjected to plasma treatment on its surface. The plasma treatment may be performed using RF plasma or an ion beam. The plasma treatment may be performed on one or both sides of the substrate. The plasma treatment not only enhances the chemical activity of the substrate surface but also improves the surface roughness, thereby further enhancing the peel strength between the polyimide-based substrate and the first copper layer or the second copper layer.

[0059] A first nickel layer or a second nickel layer may be positioned on the first surface or the second surface of the polyimide-based substrate. A copper-clad laminate film including the first nickel layer or the second nickel layer is easy to etch because no transition metal such as chromium is detected when etched with an acidic etchant such as an etchant containing ferric chloride, compared to a copper-clad laminate film including an alloy layer of nickel and another transition metal. For example, a general nickel-chromium alloy sputtered layer retains chromium when etched with an acidic etchant, but a nickel layer does not use any chromium that was not etched when etched with an acidic etchant, so no chromium is detected.

[0060] The thickness of the first nickel layer or the second nickel layer may be 3 nm to 10 nm. For example, the thickness of the first nickel layer or the second nickel layer may be 3.1 nm to 9 nm, 3.2 nm to 9 nm, 3.3 nm to 8 nm, 3.4 nm to 7 nm, or 3.5 nm to 6 nm. When the thickness of the first nickel layer or the second nickel layer is within the above range, the peel strength between the polyimide-based substrate and the first copper layer or the second copper layer can be improved, while the flexibility of the copper-clad laminate film can be improved. Therefore, it is suitable for use in electronic devices such as flexible printed circuit boards and / or camera coils requiring fine patterns.

[0061] The first copper layer and the second copper layer may each include a copper sputter layer and an electrolytic copper plating layer. The copper sputter layer may be formed on the first nickel layer or the second nickel layer by 10 -4 10 inland -2 It may be a layer deposited by sputtering in a vacuum tank under reduced pressure of 10 torr. Any sputtering method available in the relevant technical field may be used for sputtering, but for example, physical vapor deposition (PVD), chemical vapor deposition (CVD), low-pressure chemical vapor deposition (LPCVD), or vacuum deposition may be used.

[0062] The thickness of the copper sputter layer may be 50 nm to 150 nm. For example, the thickness of the copper sputter layer may be 50 nm to 140 nm, 50 nm to 130 nm, or 50 nm to 120 nm. If the thickness of the copper sputter layer is within the above range, conductivity can be secured during film formation and low surface roughness (R z ) can be provided.

[0063] The electrolytic copper plating layer may be disposed on the opposite surface of the copper sputtered layer that is in contact with the first nickel layer or the second nickel layer. Electrolytic plating may be performed using a method commonly used in the art.

[0064] Electroplating is performed by, for example, forming a copper plating layer on the copper sputter layer by performing electroplating using copper sulfate and sulfuric acid as base materials. Electroplating can be performed using a plating solution containing copper at a concentration of 15 g / L to 40 g / L, for example, 15 g / L to 38 g / L, for example, 17 g / L to 36 g / L. Electroplating can be performed while maintaining the temperature of the plating solution at 22°C to 37°C, for example, 25°C to 35°C, for example, 27°C to 34°C. Within the temperature range of the plating solution, formation of a plating layer is easy and excellent productivity can be achieved.

[0065] Optionally, one or more pH adjusters may be included in the plating solution. The pH adjusters may include organic acids, inorganic acids, organic bases, inorganic bases, or mixtures thereof. For example, the inorganic acid may include phosphoric acid, nitric acid, sulfuric acid, hydrochloric acid, or a combination thereof. For example, the inorganic base may include ammonium hydroxide, sodium hydroxide, potassium hydroxide, or a combination thereof. For example, the pH of the plating solution may be greater than 7. For this purpose, the pH may be adjusted with an inorganic base such as sodium hydroxide. Meanwhile, the plating solution may contain known additives such as brighteners, levelers, correctors, and softeners for productivity and surface uniformity.

[0066] Electroplating can be performed under conditions of a current density of 0.1 A / m² to 20 A / m², for example, 0.1 A / m² to 17 A / m², for example, 0.3 A / m² to 15 A / m². Within the above range of current density, a copper plating layer can be easily formed and excellent productivity can be achieved.

[0067] The thickness of the first copper layer or the second copper layer may be 10% to less than 25% of the thickness of the polyimide-based substrate. For example, the thickness of the first copper layer or the second copper layer may be 11% to less than 25% or 12% to less than 25% of the thickness of the polyimide-based substrate. When the thickness of the first copper layer or the second copper layer is within the above range, the flexibility may be further improved, and the peel strength between the polyimide-based substrate and the first copper layer or the second copper layer may be further improved.

[0068] When etching the surface of the first or second copper layer with an etchant containing ferric chloride, chromium may not be detected by EDAX (Energy Dispersive Spectroscopy) or EPMA (Electron Probe MicroAnalysis). Therefore, the problem of a pattern not being clearly formed due to remaining chromium components after etching with an acidic etchant, such as an etchant containing ferric chloride, on the surface of the first or second copper layer does not occur.

[0069] The height of the curl on the film surface may be less than 0.1 mm. For example, the height of the curl on the film surface may be less than 0.05 mm, less than 0.001 mm, or 0 mm.

[0070] The film can satisfy the peel strength according to the following equation 1:

[0071] [Formula 1]

[0072] 0.3 ≤ |P1 - P2| ≤ 0.5

[0073] Among the foods,

[0074] P1 is the peel strength (kgf / in) of the first copper layer or the second copper layer on the polyimide-based substrate measured at a speed of 50 mm / min and an angle of 180° after the film has been left at room temperature for 4 hours,

[0075] P2 is the peel strength (kgf / in) of the first copper layer or the second copper layer on the polyimide-based substrate, measured at a speed of 50 mm / min and an angle of 180° after the film was heat-treated at 150°C for 2 hours, left at room temperature for 30 minutes twice, and further heat-treated at 240°C for 10 minutes.

[0076] The film may have a fatigue life of at least 200,000 cycles as measured by MIT in accordance with JIS C 6471. For example, the film may have a fatigue life of at least 190,000 cycles as measured by MIT in accordance with JIS C 6471.

[0077] A printed circuit board according to another embodiment may include the double-sided copper-clad laminate film described above. The printed circuit board may be a flexible printed circuit board.

[0078] According to another embodiment, a method for manufacturing a double-sided copper-clad laminate film includes the steps of: providing a polyimide-based substrate having a thickness of more than 10 ㎛ to 30 ㎛; sequentially forming a first nickel layer and a first copper layer on a first surface of the polyimide-based substrate; and sequentially forming a second nickel layer and a second copper layer on a second surface of the polyimide-based substrate to manufacture a double-sided copper-clad laminate film; wherein the thickness of the first copper layer or the second copper layer is 10% to less than 25% based on the thickness of the polyimide-based substrate, and when etching the surface of the first copper layer or the second copper layer with an etchant containing ferric chloride, chromium is not detected by EDAX (Energy Dispersive Spectroscopy) or EPMA (Electron Probe MicroAnalysis), and the height of curl on the film surface may be less than 0.1 mm. The above-described method for manufacturing a double-sided copper-clad laminate film can improve process contamination even when using a high-temperature manufacturing process. A double-sided copper-clad laminate film manufactured using this method exhibits excellent peel strength and flexibility without folding, wrinkling, or curling of the film, and is easy to etch as no chromium components are detected after acid etching.

[0079] The step of providing the above polyimide-based substrate may be a method of providing the polyimide-based substrate using a roll-to-roll process that can control the tensions at both ends and the center of the roll. In the roll-to-roll process, a control system equipped with a tension sensor can be used to control the tensions at both ends and the center of the roll. The inlet and outlet tensions are controlled through the control system equipped with the tension sensor. The tension sensors are located at the front and end of the main panel. The control system may include an input unit for inputting one or more characteristic values ​​related to a polyimide-based substrate from a user, a receiving unit for receiving a measured tension value from a tension sensor, a database unit for storing a plurality of standard values ​​related to the polyimide-based substrate and a plurality of target tension values ​​matching the standard values, a search module for receiving the characteristic values ​​and searching the database unit for a standard value corresponding to an approximate value of the received characteristic value and a target tension value matching the standard value, a control module for comparing the received measured tension value with the searched target tension value and then controlling the measured tension value so that the measured tension value is identical to the target tension value, a control unit configured with a signal generation module for generating a selection signal so that a voltage corresponding to the target tension value is output, and an output unit for outputting a voltage corresponding to the target tension value so that the target tension value is reached. The control module generates a control signal to increase the measured tension value to the target tension value when the measured tension value is lower than the target tension value, or generates a control signal to decrease the measured tension value to the target tension value when the measured tension value is higher than the target tension value. If necessary, it includes a signal generation module including a conversion module selection signal generation module that generates a conversion module selection signal for selecting each change module for current and voltage stress in response to the control signal.

[0080] The thickness of the first nickel layer or the second nickel layer may be 3 nm to 10 nm. For example, the thickness of the first nickel layer or the second nickel layer may be 3.1 nm to 9 nm, 3.2 nm to 9 nm, 3.3 nm to 8 nm, 3.4 nm to 7 nm, or 3.5 nm to 6 nm. When the thickness of the first nickel layer or the second nickel layer is within the above range, the peel strength between the polyimide-based substrate and the first copper layer or the second copper layer can be improved, while the flexibility of the copper-clad laminate film can be improved. Therefore, it is suitable for use in electronic devices such as flexible printed circuit boards and / or camera coils requiring fine patterns.

[0081] The first copper layer and the second copper layer may each include a step of forming a copper seed layer by sputtering and a step of forming a copper electroplating layer. The sputtering and copper electroplating methods are as described above.

[0082] The film can satisfy the peel strength according to the following equation 1:

[0083] [Formula 1]

[0084] 0.3 ≤ |P1 - P2| ≤ 0.5

[0085] Among the foods,

[0086] P1 is the peel strength (kgf / in) of the first copper layer or the second copper layer on the polyimide-based substrate measured at a speed of 50 mm / min and an angle of 180° after the film has been left at room temperature for 4 hours,

[0087] P2 is the peel strength (kgf / in) of the first copper layer or the second copper layer on the polyimide-based substrate, measured at a speed of 50 mm / min and an angle of 180° after the film was heat-treated at 150°C for 2 hours, left at room temperature for 30 minutes twice, and further heat-treated at 240°C for 10 minutes.

[0088] The film may have a fatigue life of at least 200,000 cycles as measured by MIT in accordance with JIS C 6471. For example, the film may have a fatigue life of at least 190,000 cycles as measured by MIT in accordance with JIS C 6471.

[0089]

[0090] Hereinafter, the composition and resulting effects of the present invention will be described in more detail through examples and comparative examples. However, it should be understood that these examples are intended to illustrate the present invention more specifically, and that the scope of the present invention is not limited to these examples.

[0091]

[0092] [Example]

[0093]

[0094] Example 1: Double-sided copper-clad laminate film

[0095] A double-sided copper-clad laminate film was manufactured using a roll-to-roll process as follows. The roll-to-roll process used a system equipped with a tension sensor to control the tension at both ends and the center of the roll.

[0096] As a substrate, a polyimide film (Kapton 50ENC, manufactured by TDC) having a thickness of about 12.5 ㎛ was wound into a roll, and the tension at both ends of the roll was controlled to be about 20% greater than the tension at the center. A first nickel layer having a thickness of about 3.5 nm and a first copper seed layer having a thickness of about 100 nm were sequentially formed on the first surface of the polyimide film by physical vapor deposition (PVD) using a roll-to-roll type sputtering device. At this time, the first nickel layer used nickel having a purity of 99.9% or more, and the first copper seed layer used copper having a purity of 99.995%. A first copper plating layer having a thickness of about 1.5 ㎛ was formed on the first copper seed layer by electrolytic copper plating. The electrolytic copper plating solution used was Cu 2+A copper sulfate plating solution having a concentration of 28 g / L and sulfuric acid content of 190 g / L was used, and additionally containing 0.01 g / L of 3-N,N-dimethylaminodithiocarbamoyl-1-propanesulfonic acid as a brightener and a corrector (manufactured by Atotech). Electroplating was performed at 30°C, and a current was applied at a current density of 2.0 A / m² to form the film. Then, a second nickel layer having a thickness of about 3.5 nm, a second copper seed layer having a thickness of about 100 nm, and a second copper plating layer having a thickness of about 1.5 μm were sequentially formed on the second surface of the polyimide film in the same manner as described above, thereby manufacturing a double-sided copper clad laminate film. At this time, the thickness of the first copper seed layer and the first copper plating layer (i.e., the first copper layer) or the thickness of the second copper seed layer and the second copper plating layer (i.e., the second copper layer) was approximately 12.8% based on the thickness of the polyimide film.

[0097]

[0098] Example 2: Double-sided copper-clad laminate film

[0099] A double-sided copper-clad laminate film was manufactured in the same manner as in Example 1, except that a first copper plating layer or a second copper plating layer having a thickness of about 3 μm was formed on the first copper seed layer or the second copper seed layer by electrolytic copper plating. At this time, the thickness of the first copper seed layer and the first copper plating layer (i.e., the first copper layer) or the thickness of the second copper seed layer and the second copper plating layer (i.e., the second copper layer) was about 24.8% based on the thickness of the polyimide film.

[0100]

[0101] Comparative Example 1: Double-sided copper-clad laminate film

[0102] A double-sided copper-clad laminate film was manufactured in the same manner as in Example 1, except that a first copper plating layer or a second copper plating layer having a thickness of about 5 μm was formed on the first copper seed layer or the second copper seed layer by electrolytic copper plating.

[0103]

[0104] Comparative Example 2: Double-sided copper-clad laminate film

[0105] A double-sided copper-clad laminate film was manufactured in the same manner as in Example 1, except that a first copper plating layer or a second copper plating layer having a thickness of about 0.5 μm was formed on the first copper seed layer or the second copper seed layer by electrolytic copper plating.

[0106]

[0107] Comparative Example 3: Double-sided copper-clad laminate film

[0108] A double-sided copper-clad laminate film was manufactured in the same manner as Example 1, except that a first nickel-chromium alloy layer or a second nickel-chromium alloy layer was formed instead of a first nickel layer or a second nickel layer on the first or second side of the polyimide film. The first nickel-chromium alloy layer and the second nickel-chromium alloy layer were formed to a thickness of about 3.5 nm with a weight ratio of Ni and Cr of 80:20 (purity: 99.9% or more).

[0109]

[0110] Comparative Example 4: Double-sided copper-clad laminate film

[0111] A polyimide film (Kapton 50ENC, manufactured by TDC) having a thickness of approximately 12.5 μm was prepared as a substrate. A protective film (LE951, manufactured by Toyo) having a thickness of approximately 50 μm and consisting of an acrylic adhesive layer and a polyethylene terephthalate (PET) film was laminated to the first surface of the polyimide film. A first nickel-chromium alloy layer and a first copper seed layer were sequentially formed on the opposite surface of the polyimide film to which the protective film was laminated using a roll-to-roll type sputtering device by physical vapor deposition (PVD). The first nickel-chromium alloy layer was formed to a thickness of approximately 3.5 nm with a weight ratio of nickel to chromium of 80:20 (purity: 99.9% or higher), and the first copper seed layer was formed to a thickness of approximately 100 nm using copper having a purity of 99.995%.

[0112] A first copper plating layer of about 3 ㎛ thickness was formed on the first copper seed layer by electrolytic copper plating. The electrolytic copper plating solution used was Cu 2+ A copper sulfate plating solution having a concentration of 28 g / L and sulfuric acid content of 190 g / L was used, and a solution containing 0.01 g / L of 3-N,N-dimethylaminodithiocarbamoyl-1-propanesulfonic acid as a brightener and a corrector (Atotech) was additionally used. Electroplating was performed at 30°C, and a current density of 2.0 A / m² was applied to form the film. The protective film was then reverse-wound. In addition, a protective film (LE951, manufactured by Toyo) having a thickness of about 50 μm and composed of an acrylic adhesive layer and a polyethylene terephthalate (PET) film was laminated to the second surface of the polyimide film in the same manner as described above, and a second nickel-chromium alloy layer having a thickness of about 3.5 nm, a second copper seed layer having a thickness of about 100 nm, and a second copper plating layer having a thickness of about 3 μm were sequentially formed on the opposite surface of the polyimide film to which the protective film was laminated, and then the protective film was reverse-wound to manufacture a double-sided copper-clad laminate film.

[0113] At this time, the thickness of the first copper seed layer and the first copper plating layer (i.e., the first copper layer) or the thickness of the second copper seed layer and the second copper plating layer (i.e., the second copper layer) is about 24.8% based on the thickness of the polyimide film.

[0114]

[0115] Comparative Example 5: Double-sided copper-clad laminate film

[0116] A double-sided copper-clad laminate film was manufactured in the same manner as in Example 1, except that a first copper seed layer or a second copper seed layer having a thickness of about 100 nm was formed on the first or second side of the polyimide film by physical vapor deposition (PVD) using a roll-to-roll type sputtering device.

[0117]

[0118] Evaluation Example 1: Physical Property Evaluation

[0119] The physical properties of each double-sided copper-clad laminate film manufactured in Examples 1 to 2 and Comparative Examples 1 to 5 were evaluated as follows. The results are shown in Table 1 below, and some of the results are shown in FIGS. 2 and 3, respectively.

[0120]

[0121] (1) Thickness of nickel layer and copper layer (nm / ㎛)

[0122] The thicknesses of the first nickel layer, the second nickel layer, the first copper layer, and the second copper layer of each double-sided copper-clad laminate film were measured using a FIB (Focused Ion Beam)-TEM device. The results are shown in Table 1.

[0123]

[0124] (2) Chromium content detected after acid etching (ppm) - EDX / EPMA

[0125] A circuit pattern with a width of 3 mm was formed on the surface of each double-sided copper-clad laminate film, and the opposite surface of the entire copper-clad laminate film on which the circuit pattern was formed was etched with an etchant containing ferric chloride, and the content of chromium components detected by EDX / EPMA (Titan G2 ChemiSTEM Cs Probe, FEI Company) was analyzed. The results are shown in Table 1.

[0126]

[0127] (3) Curl height (mm)

[0128] Each double-sided copper-clad laminate film was cut to a size of 500 mm x 500 mm to prepare a sample. The prepared sample was then placed on a table, and the height of the curl was measured by adjusting the eye level to the table surface (reference surface) and measuring the part protruding from the center or end surface of the sample with a ruler. The photographs measuring the curl height of the double-sided copper-clad laminate films manufactured according to Example 1 and Comparative Example 1 are shown in FIGS. 2 and 3, respectively.

[0129]

[0130] (4) Peel strength of copper layer on substrate (kgf / in)

[0131] The room temperature peel strength (P1) and high temperature peel strength (P2) were measured using the following methods, and the absolute value of the difference between the room temperature peel strength (P1) and high temperature peel strength (P2) was calculated. The results are shown in Table 1.

[0132] 1) Room temperature peel strength (P1)

[0133] For each double-sided copper-clad laminate film, a sample was prepared by cutting a 3 mm wide line. The sample was left at room temperature for 4 hours, and then the peel strength (kgf / in) of the first copper layer to the substrate was measured by peeling at a speed of 50 mm / min and an angle of 180° using a peel strength tester (AG-50NIS, SHIMAZU).

[0134] 2) High temperature peel strength (P2)

[0135] For each double-sided copper-clad laminate film, a sample was prepared by cutting a 3 mm wide line. The sample was heat-treated at 150°C for 2 hours, left at room temperature for 30 minutes twice, and further heat-treated at 240°C for 10 minutes. Then, the peel strength (kgf / in) of the first copper layer relative to the substrate was measured at a speed of 50 mm / min and an angle of 180° using a peel strength tester (AG-50NIS, SHIMAZU).

[0136]

[0137] (5) MIT fatigue life (times)

[0138] For each double-sided copper-clad laminate film, the fatigue life was evaluated using an MIT flexural tester according to JIS C 6471. The results are shown in Table 1.

[0139] Fatigue life was evaluated by measuring it through an experiment using the MIT flexural tester.

[0140] Each double-sided copper-clad laminate film was cut to a size of 15 mm x 170 mm to form a pattern (width: 1000 ㎛), etched with an acid solution, stored for 24 hours, and stored in an 80 ℃ oven for 1 hour to prepare a sample. One end of the prepared sample in the longitudinal direction was fixed to the nip jig of an MIT bending tester, and the other end was fixed with a weight (500 g load). (+) and (-) electrodes were hung on both ends of the sample, and the sample was bent so that the radius of curvature became 0.38 mm while rotating it alternately left and right at an angle of 135±5° around the nip portion, and the number of times until the sample was short-circuited was measured. The MIT bending tester used was SFT-9250, TOYO SEIKI equipment.

[0141]

[0142] As shown in Table 1, the double-sided copper-clad laminate films according to Examples 1 and 2 had a thickness of the first copper layer or the second copper layer of about 12.8% and about 24.8%, respectively, based on the thickness of the polyimide-based substrate, and no chromium was detected after acid etching and the curl height was less than 0.1 mm. In addition, the double-sided copper-clad laminate films according to Examples 1 and 2 had a peel strength |P1 - P2| of the first copper layer to the substrate of 0.37 and an MIT fatigue life of 250,000 times or more.

[0143] In comparison, the double-sided copper-clad laminate films according to Comparative Examples 1 and 2 had a thickness of the first copper layer or the second copper layer of 40% and 4%, respectively, based on the thickness of the polyimide-based substrate, a peel strength |P1 - P2| of the first copper layer with respect to the substrate of 0.24, and a low MIT fatigue life of 180,000 times and 80,000 times, respectively.

[0144] The double-sided copper-clad laminate film according to Comparative Example 3 formed a first nickel-chromium alloy layer or a second nickel-chromium alloy layer on the first side or the second side of a polyimide film, and the chromium content detected after acid etching was 0.03 ppm and the curl height was as high as 25 mm.

[0145] The double-sided copper-clad laminate film according to Comparative Example 4 was a double-sided copper-clad laminate film with a protective film laminated thereto, and the chromium content detected after acid etching was 0.03 ppm, and the MIT fatigue life was low at 170,000 cycles.

[0146] The double-sided copper-clad laminate film according to Comparative Example 5 did not include the first nickel layer or the second nickel layer, and had a high curl height of 25 mm, a peel strength |P1 - P2| of the first copper layer to the substrate of 0.16, and a low MIT fatigue life of 110,000 cycles, respectively.

[0147]

[0148] From this, the double-sided copper-clad laminate films according to Examples 1 and 2 are easy to etch because no chromium is detected after acid etching, and have excellent peel strength and flexibility, so they are suitable for application to printed circuit boards, specifically, flexible printed circuit boards (FPCBs) or flexible copper-clad laminate films requiring fine circuit patterns.

[0149]

[0150] [Explanation of symbols]

[0151] 400: First copper layer, 410: First nickel layer, 420: Polyimide-based substrate

[0152] 430: Second nickel layer, 440: Second copper layer, 480: Double-sided copper-clad laminate film

Claims

A polyimide-based substrate having a thickness of more than 1.10 ㎛ to 30 ㎛; A first nickel layer located on the first surface of the polyimide-based substrate; A first copper layer located on a surface of the first nickel layer opposite to the first surface of the polyimide-based substrate; A second nickel layer located on the second surface of the polyimide-based substrate; and A second copper layer located on a surface of the second nickel layer opposite to the second surface of the polyimide-based substrate; The thickness of the first copper layer or the second copper layer is less than 10% to 25% based on the thickness of the polyimide-based substrate, When etching the surface of the first copper layer or the second copper layer with an etching solution containing ferric chloride, chromium is not detected by EDAX (Energy Dispersive Spectroscopy) or EPMA (Electron Probe MicroAnalysis). A double-sided copper-clad laminate film having a curl height of less than 0.1 mm on the film surface.

2. In paragraph 1, A double-sided copper-clad laminate film, wherein the thickness of the first nickel layer or the second nickel layer is 3 nm to 10 nm.

3. In paragraph 1, A double-sided copper-clad laminate film, wherein the first copper layer and the second copper layer each include a copper sputter layer and an electrolytic copper plating layer.

4. In paragraph 1, A double-sided copper-clad laminate film satisfying the peel strength according to the following formula 1: [Formula 1] 0.3 ≤ |P1 - P2| ≤ 0.5 Among the foods, P1 is the peel strength (kgf / in) of the first copper layer or the second copper layer on the polyimide-based substrate measured at a speed of 50 mm / min and an angle of 180° after the film has been left at room temperature for 4 hours, P2 is the peel strength (kgf / in) of the first copper layer or the second copper layer on the polyimide-based substrate, measured at a speed of 50 mm / min and an angle of 180° after the film was heat-treated at 150°C for 2 hours, left at room temperature for 30 minutes twice, and further heat-treated at 240°C for 10 minutes.

5. In paragraph 1, Double-sided copper-clad laminate film with a fatigue life of 200,000 cycles or more as measured by MIT according to JIS C 6471.

6. A printed circuit board comprising a double-sided copper-clad laminate film according to any one of clauses 1 to 5. A step of providing a polyimide-based substrate having a thickness of more than 7.10 ㎛ to 30 ㎛; A step of sequentially forming a first nickel layer and a first copper layer on the first surface of the polyimide-based substrate; and A step of manufacturing a double-sided copper-clad laminate film by sequentially forming a second nickel layer and a second copper layer on the second surface of the polyimide-based substrate; The thickness of the first copper layer or the second copper layer is less than 10% to 25% based on the thickness of the polyimide-based substrate, When etching the surface of the first copper layer or the second copper layer with an etching solution containing ferric chloride, chromium is not detected by EDAX (Energy Dispersive Spectroscopy) or EPMA (Electron Probe MicroAnalysis). A method for manufacturing a double-sided copper-clad laminate film having a curl height of less than 0.1 mm on the film surface.

8. In paragraph 7, A method for manufacturing a double-sided copper-clad laminate film, wherein the step of providing the polyimide-based substrate is to provide the polyimide-based substrate using a roll-to-roll process that can be controlled so that the ends and the center of the roll have different tensions.

9. In paragraph 7, A method for manufacturing a double-sided copper-clad laminate film, wherein the thickness of the first nickel layer or the second nickel layer is 3 nm to 10 nm.

10. In paragraph 7, A method for manufacturing a double-sided copper-clad laminate film, wherein the first copper layer and the second copper layer each include a step of forming a copper seed layer by sputtering and a step of forming a copper electroplating layer.

11. In paragraph 7, A method for manufacturing a double-sided copper-clad laminate film that satisfies the peel strength according to the following formula 1: [Formula 1] 0.3 ≤ |P1 - P2| ≤ 0.5 Among the foods, P1 is the peel strength (kgf / in) of the first copper layer or the second copper layer on the polyimide-based substrate measured at a speed of 50 mm / min and an angle of 180° after the film has been left at room temperature for 4 hours, P2 is the peel strength (kgf / in) of the first copper layer or the second copper layer on the polyimide-based substrate, measured at a speed of 50 mm / min and an angle of 180° after the film was heat-treated at 150°C for 2 hours, left at room temperature for 30 minutes twice, and further heat-treated at 240°C for 10 minutes.

12. In paragraph 7, A method for manufacturing a double-sided copper-clad laminate film having a fatigue life of 200,000 cycles or more as measured by MIT according to JIS C 6471.

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