JP6060854B2 - Surface treatment method for resin film and method for producing copper clad laminate including the same - Google Patents

Description

  The present invention relates to a surface treatment method applied to a resin film before the film formation process of the resin film, and in particular, for improving adhesion before performing film formation such as sputtering while conveying a long resin film. The present invention relates to a surface treatment method applied to the long resin film.

  In a liquid crystal panel, a notebook computer, a digital camera, a mobile phone, and the like, a flexible wiring board in which a wiring pattern is formed on a heat resistant resin film is used. This flexible wiring board can be obtained by patterning a copper-clad laminate in which a copper thin film is formed on one side or both sides of a heat resistant resin film. In recent years, wiring patterns tend to be more delicate and denser, and accordingly, copper-clad laminates themselves are required to be smooth without wrinkles.

  As a method for producing a heat-resistant resin film with a metal film typified by the copper-clad laminate described above, conventionally, a method for producing a metal foil attached to a heat-resistant resin film with an adhesive (a method for producing a three-layer substrate), A metal film coated with a heat-resistant resin solution on a metal foil and dried (casting method), a vacuum film-forming method alone on a heat-resistant resin film, or a combination of a vacuum film-forming method and a wet plating method. A method (metalizing method) for producing a film by forming a film is known. Examples of the vacuum film forming method used for the metalizing method include a vacuum deposition method, a sputtering method, an ion plating method, and an ion beam sputtering method.

  Regarding the metallizing method, Patent Document 1 describes a method of forming a conductor layer by sputtering copper after sputtering a chromium layer on a polyimide insulating layer. Patent Document 2 discloses a flexible circuit in which a first metal thin film formed by sputtering using a copper-nickel alloy as a target and a second metal thin film formed by sputtering using a copper as a target are formed in this order on a polyimide film. A substrate material is disclosed.

  Film formation by these sputtering methods is generally excellent in adhesion, but it is said that the heat load applied to the heat-resistant resin film as a base material is larger than that in the vacuum evaporation method. It is also known that when a large heat load is applied to the heat resistant resin film during film formation, the film is likely to be wrinkled. Therefore, in order to prevent the generation of wrinkles, a sputtering web coater is generally used in the process of forming a heat resistant resin film with a metal film by forming a film on a heat resistant resin film such as a polyimide film by a vacuum film forming method. Is used. This apparatus includes a can roll in which a refrigerant is circulated, and a long heat-resistant resin film conveyed by roll-to-roll is wound around the outer peripheral surface of the can roll and cooled from the back side. Sputtering is performed.

  By the way, in the production process of the heat-resistant resin film with a metal film as described above, in order to further improve the adhesion between the heat-resistant resin film and the metal film, the heat-resistant resin film is previously subjected to plasma treatment or ion beam irradiation treatment. Application is known to be effective. For example, Patent Document 3 discloses not only initial adhesion but also adhesion in a high-temperature environment and a high-temperature and high-humidity environment by regulating the thickness of the modified layer on the polyimide film surface formed by plasma treatment to a predetermined value or less. The technology to improve the balance is shown. Further, in Patent Document 4, when the surface modification of polyimide is performed by a dry method, only the initial adhesion force can be obtained by suppressing the thickness of the mixed layer of polyimide and metal formed by the modification to a predetermined value or less. A technique for improving the adhesion after aging is disclosed.

Japanese Patent Laid-Open No. 2-98994 Japanese Patent No. 3447070 JP 2007-318177 A International Publication No. 2010/098236 Pamphlet

  However, in the plasma treatment, if excessive plasma treatment is performed to improve the initial peel strength, the PCT peel strength (Pressure Cooker Test 121 ° C. × 95% × 2 atm × 100), which is an index of adhesion in a high temperature and high humidity environment. The heat-resistant peel strength (150 ° C. × 168 hours), which is an index of adhesion strength in a high temperature environment, may be significantly reduced compared to (time). This reduction in heat-resistant peel strength results in the formation of a thick modified layer on the polyimide surface due to excessive plasma treatment, and the oxygen contained in the modified layer oxidizes the underlying metal layer, reducing the adhesion to the polyimide. It is thought that it is to do.

  The present invention has been made paying attention to such conventional problems, and in the step of forming a metal film on a resin film by sputtering, the resin film and the metal film can be formed without reducing the heat-resistant peel strength. An object of the present invention is to provide a pretreatment method capable of increasing the adhesion.

In order to solve the above-mentioned problems, the surface treatment method for a resin film of the present invention is a surface treatment method prior to film formation on a resin film by a dry plating method in a reduced-pressure atmosphere, wherein after removing the fragile layer on the surface of the resin film by performing a process of irradiating the ion beam of the ion beam voltage 600～3000V (excluding 3000 V), and performs a process of irradiating plasma on the same surface, the In the plasma irradiation process, in the correlation between the plasma voltage and the peel strength obtained in advance, the plasma voltage is higher than the plasma voltage when the PCT peel strength starts to drop when the plasma voltage is lowered and the plasma voltage is raised. the heat-resistant peel strength is applied a plasma voltage of the plasma voltage following range when starts to decrease when Tsu It is characterized.

  According to the present invention, in a heat-resistant resin film substrate with a metal film obtained by performing sputtering film formation on a long heat-resistant resin film substrate conveyed by roll-to-roll, in addition to high initial peel strength, high PCT peel It becomes possible to achieve both strength and high heat-resistant peel strength.

It is a typical front view of the vacuum film-forming apparatus which can suitably implement one specific example of the pretreatment method concerning the present invention. It is a typical front view of the vacuum film-forming apparatus which can carry out other specific examples of the pretreatment method concerning the present invention suitably. It is a typical front view of the vacuum film-forming apparatus which can implement the pre-processing method of a reference example. In Example 1, it is a graph which shows the relationship between the ion beam voltage and peel strength in the conveyance speed of 6 m / min. In Example 1, it is a graph which shows the relationship between the ion beam voltage and peel strength in the conveyance speed of 8 m / min.

  First, a long resin film vacuum film forming apparatus that can suitably carry out the pretreatment method of the present invention will be described with reference to FIG. 1 by taking a roll-to-roll sputtering apparatus as an example. 1 is a continuous film forming apparatus also called a sputtering web coater, and is a long heat-resistant resin film (hereinafter referred to as unrolled roll) in an unwinding chamber 210. F is first pre-treated in the ion beam chamber 234 and the plasma chamber 239, and then subjected to film formation in the film formation chamber 211 and taken up by a take-up roll 229 in the take-up chamber 212. It has become.

  More specifically, the resin film F is unwound from the unwinding roll 214 in the unwinding chamber 210, and is measured in the tension sensor roll 215 before being sent into the heater box 216, where the heater 217, The front and back surfaces are dried by 218. The dried resin film F is sent to the ion beam chamber 234 through a free roll 219.

  In the ion beam chamber 234, the ion beam is guided to the first cooling roll 236 through the free roll 235, and the resin film F is wound around the outer peripheral surface of the first cooling roll 236 and cooled from the back side, and is subjected to heat load. Beam processing is performed. This ion beam treatment is performed by irradiating the resin film F with an ion beam from an ion beam irradiation device 238 provided so as to face the outer peripheral surface of the first cooling roll 236. The resin film F subjected to the ion beam treatment is sent to the plasma chamber 239 through the free roll 237.

  In the plasma chamber 239, it is guided to the second cooling roll 241 through the free roll 240, where the resin film F is wound around the outer peripheral surface of the second cooling roll 241 and cooled from the back side while being subjected to a heat treatment. Is given. This plasma treatment is performed by irradiating the resin film F with plasma from a plasma generator 243 provided so as to face the outer peripheral surface of the second cooling roll 241. The resin film F plasma-treated in the plasma chamber 239 passes through the free roll 242 and then enters the film formation chamber 211. The ion beam chamber 234 and the plasma chamber 239 are isolated from each other, and the atmosphere gas composition and pressure can be controlled separately so that the processing atmospheres are different from each other.

  In the film forming chamber 211, the resin film F is guided to the water-cooled can roll 223 through the free roll 220, the tension sensor roll 221, and the front feed roll 222. Here, while the resin film F is wound around the outer peripheral surface of the water-cooled can roll 223 and cooled from the back surface side, a film forming process is performed by the sputtering cathodes 230, 231, 232, and 233.

  By attaching a plate-like sputtering target to the sputtering cathodes 230 to 233, for example, a metal layer made of a nickel-chromium alloy as a base metal layer and a copper thin film layer made of a copper layer as a metal layer thereon are formed. A film can be formed, thereby obtaining a copper clad laminate. In the plate-like sputtering target, nodules (foreign substance growth) may occur on the target. When this becomes a problem, a cylindrical rotary target that does not generate nodules and has high target use efficiency may be used. In addition, the composition of the base metal layer is selected according to desired characteristics such as electrical insulation and migration resistance of the copper clad laminate, and the material is Ni—Cr alloy, Inconel, Constantan, Monel, etc. Alloys can be used.

In the film formation chamber 211, for the above-described sputtering film formation, a pressure reduction to an ultimate pressure of about 10 ⁻⁴ Pa and a subsequent pressure adjustment of about 0.1 to 10 Pa by introduction of a sputtering gas are performed. A known gas such as argon is used as the sputtering gas, and a gas such as oxygen is further added according to the purpose. Therefore, various devices such as a dry pump, a turbo molecular pump, and a cryocoil (not shown) are provided. Note that there are no particular limitations on the shape or material of the vacuum chamber that forms the film formation chamber 211, as long as it can withstand such a reduced pressure state, and various types can be used. The resin film F that has been subjected to film formation is sent to the take-up chamber 212 via a rear feed roll 224, a tension sensor roll 225, and a free roll 226.

  The resin film F that has entered the take-up chamber 212 passes through the free roll 227 and the tension sensor roll 228, and is then taken up by the take-up roll 229. In FIG. 1, some free rolls and vacuum exhaust equipment for changing the transport direction of the resin film F are not shown. Further, the rotation speeds of the unwinding roll, the front feed roll, the rear feed roll, and the cooling roll are controlled by each tension sensor roll.

  A resin film with a metal thin film in which a metal layer having a predetermined film thickness is laminated by the above-described continuous series of treatments is obtained. In addition, depending on the film thickness of the target copper layer, when the copper-clad laminate is completed only with the resin film with the metal thin film, the surface of the copper thin film layer is further subjected to copper plating by wet plating, and the film thickness of the copper layer May be completed as a copper-clad laminate with increased thickness. In this wet plating method, there are a case where a metal film is formed only by an electroplating treatment, and an electroless plating treatment as a primary plating and an electrolytic plating treatment as a secondary plating are combined. In addition, various conditions of a general wet plating method can be employed for these wet plating processes.

  Next, the ion beam treatment and the plasma treatment will be examined in more detail. The ion beam treatment has a high directivity of the ion beam to be irradiated, and has an action of scraping the surface of the object to be processed by sputtering the surface of the object to be processed with the ion beam to knock out the particles. By performing ion beam irradiation treatment using this action, it is possible to remove the fragile layer on the surface of the resin film that causes a decrease in the adhesion between the resin film and the film formed on the surface.

  The fragile layer will be described. In the process of producing a resin film, for example, a polyimide film is produced by condensation polymerization using a known solution casting method. This polycondensation usually imidizes the polyamic acid as a precursor, but heating at a high temperature is required to fully imidize the polyamic acid. Moreover, in order to provide the toughness as a polyimide film, it is necessary to express sufficient packing between molecular chains, and for that purpose, it is necessary to heat at a high temperature. However, when heated at a high temperature, the fragile layer described above may occur on the surface of the polyimide film.

  As a countermeasure, a method for improving the adhesion of the polyimide film by controlling the heating temperature and the heating time in the production conditions of the polyimide film is known. However, in this method, the fragile layer is not uniform due to heat transfer. There was a case. Alternatively, it is conceivable to remove the fragile layer with a chemical solution such as sand blasting or alkali, but in this case, the surface of the resin film cannot be continuously treated, which is not efficient. In addition, the resin film from which the fragile layer has been removed in the air easily adsorbs molecules and the like in the air, making it difficult to obtain the expected surface treatment effect.

  Therefore, in the resin film surface treatment method according to the present invention, the fragile layer on the surface of the resin film is removed by ion beam treatment in a reduced-pressure atmosphere, and then the target functional groups and the like are obtained by performing plasma treatment. Can be introduced on the surface. That is, by applying a plasma treatment under conditions in which the atmospheric gas composition is appropriately adjusted, hydrophilic functional groups such as carboxyl groups and hydroxyl groups can be introduced into the surface portion of the long resin film. The adhesion between the film F and the metal film formed on the surface thereof can be improved. For example, in the case of oxygen plasma, oxygen atoms can be added to the surface of the resin film F to introduce functional groups such as OH groups.

  Since specific ion beam treatment conditions and plasma treatment conditions vary depending on the surface treatment apparatus and the long resin film, the treatment conditions may be appropriately determined in the following procedure. That is, first, the resin film F such as polyimide is dried by the heaters 217 and 218 at a drying temperature of 180 ° C. While sending this dried resin film F to the ion beam chamber 234, the resin film F is brought into close contact with the outer peripheral surface of the first cooling roll 236 in which the cooling water whose temperature is adjusted to 10 ° C. is circulated. For example, 50 sccm of oxygen gas is introduced into the ion beam irradiation apparatus 238, and ion beam processing is performed at a predetermined potential in the range of 600 V to 3000 V in order to remove the fragile layer.

  The ion beam treatment conditions may be any conditions that can remove the fragile layer of the resin film and do not deteriorate the resin film. This can be adjusted by the treatment time in addition to the applied voltage of the ion beam. For example, when the processing conditions are changed by changing the ion beam voltage stepwise or changing the film transport speed stepwise, the thickness, initial strength, heat-resistant peel strength, and PCT when the surface of the resin film is removed. Optimum ion beam processing conditions can be determined by measuring the relationship with the peel strength in advance.

  In this ion beam treatment, in order to improve the initial peel strength (adhesion strength), if an excessive ion beam treatment is performed, the PCT peel strength (121 ° C. × 95% × 2) is more than the heat-resistant peel strength (150 ° C. × 168 hours). (Atmospheric pressure × 100 hours) is remarkably reduced, so care must be taken in determining the ion beam conditions. Further, nitrogen gas may be introduced into the ion beam irradiation apparatus 238.

  Next, the resin film F subjected to the ion beam treatment is sent to the plasma chamber 239, and the resin film F is applied to the outer peripheral surface of the second cooling roll 241 in which the cooling water whose temperature is adjusted to 10 ° C. is circulated. For example, oxygen gas is introduced at 200 sccm into the plasma generator 243 while being in close contact, and plasma treatment is performed by changing the plasma voltage stepwise within a range of 500 to 3000V. At that time, the transport distance from the start of film formation of the resin film F when the plasma voltage is changed (that is, the distance from one end portion in the longitudinal direction of the resin film F) is recorded. Then, after wet-plating as necessary to thicken the film, the obtained copper-clad laminate is determined for each plasma voltage area (determined from the transport distance when the plasma voltage is changed as described above). The test piece is cut out and linear patterning is performed on each test piece to measure the initial peel strength, the PCT peel strength, and the heat-resistant peel strength. Thereby, optimal plasma processing conditions can be determined.

  Note that nitrogen gas may be introduced into the plasma generator 243. Further, in a series of processes including the ion beam process and the plasma process, the plasma process increases the operating pressure, that is, the atmospheric gas pressure, as compared with the ion beam process. This is because the ion beam is not turned on and cannot be irradiated even if the ion beam is irradiated with the atmospheric pressure of the plasma treatment. For this reason, the ion beam chamber 234 and the plasma chamber 239 are isolated from each other, and are controlled separately so as to have different processing atmospheres.

  Next, another specific example of the surface treatment method of the present invention will be described with reference to FIG. The sputtering web coater shown in FIG. 2 is processed in the same manner as the apparatus shown in FIG. 1 except for the ion beam chamber 334 and the plasma chamber 339. In FIG. 2 and FIG. 1, among the devices indicated by the three-digit code, the devices having the same code when the three-digit code hundreds are removed are the same devices. In the apparatus shown in FIG. 2, the ion beam chamber 334 is not provided with a cooling roll, and therefore the resin film F is irradiated with an ion beam from the ion beam irradiation apparatus 338 in a so-called floating state without being cooled from the back.

  Further, the plasma chamber 339 is not provided with a cooling roll, so that the resin film F is irradiated with plasma from the plasma generator 343 in a floating state without being cooled from the back like the ion beam chamber 334. A resin film having a thickness of more than 25 μm can withstand the thermal load during plasma treatment or ion beam treatment, so that plasma irradiation or ion beam irradiation can be performed even in the above-described floating state. Also in the case of FIG. 2, the ion beam chamber 334 and the plasma chamber 339 are isolated from each other, and the atmospheric gas composition and pressure are controlled separately.

  As described above, after performing ion beam treatment for removing the fragile layer in order to increase the adhesion between the long resin film and the metal film as a pretreatment for the sputtering film forming treatment of the long resin film, The surface of the resin film from which the fragile layer has been removed by the treatment is subjected to plasma irradiation treatment to introduce a functional group, so that the initial peel strength is high, and the high PCT peel strength and the high heat-resistant peel strength are compatible. It becomes possible to manufacture a high copper-clad laminate board with high productivity.

  A flexible wiring board can be obtained by patterning this copper-clad laminate by, for example, a subtractive method. That is, a resist is formed on a copper clad laminate, a pattern is formed by a general method, and a metal film (for example, copper layer) portion not covered with the patterned resist is removed by etching. Thus, a flexible wiring board having a desired circuit pattern can be manufactured. As described above, the flexible printed circuit board thus produced has high adhesion and high quality, so that it can be used in devices that can be used in harsh environments such as notebook computers, digital cameras, and mobile phones. Therefore, the reliability of these devices can be improved.

  Since the vacuum film forming apparatus shown in FIGS. 1 and 2 performs the sputtering process, the magnetron sputtering cathode is provided as the film forming means. However, in the case of performing another vacuum film forming process. As the film forming means, a CVD (chemical vapor deposition) means, a vacuum vapor deposition means and the like are provided. Further, as the copper-clad laminate, a structure in which a metal film such as a nickel-chromium alloy or copper is laminated on a long resin film is exemplified. In addition to the metal film, an oxide film and a nitride may be used depending on the purpose. The film forming method of the present invention can be used for forming a film, a carbide film or the like.

  Examples of the heat-resistant resin film used for the copper-clad laminate include a polyimide film, a polyamide film, a polyester film, a polytetrafluoroethylene film, a polyphenylene sulfide film, a polyethylene terephthalate film, and a polyethylene naphthalate film. Alternatively, a resin film such as a liquid crystal polymer film can be used. These resin films are preferable from the viewpoints of flexibility as a flexible substrate with a metal film, strength necessary for practical use, and electrical insulation suitable as a wiring material. Furthermore, the advantageous effects as described above can be obtained even if a single-wafer type resin film is subjected to surface treatment according to the above-described procedure of the surface treatment method for a long resin film.

[Reference example]
Using a film-forming apparatus (sputtering web coater) for the resin film F shown in FIG. 3, a heat-resistant resin film with a metal film was prepared by sputtering film formation on a long heat-resistant resin film. A polyimide film “Kapton (registered trademark)” manufactured by Toray DuPont Co., Ltd. having a width of 500 mm, a length of 1000 m, and a thickness of 25 μm was used for a long heat-resistant resin film (hereinafter also referred to as resin film F). 3 is substantially the same as the apparatus of FIG. 1 except that it does not have the plasma chamber 239 provided with the plasma apparatus 243, and the apparatus indicated by the three-digit code in FIGS. Of these, when the three-digit code hundreds are removed, those having the same code are the same devices.

  For the can roll 123, a cylindrical member having a diameter of 800 mm and a width of 800 mm was used, and hard chromium plating was applied to the outer peripheral surface thereof. In addition, an IH heating roll having a diameter of 150 mm and an effective width of 500 mm is used for the front feed roll 122, and the peripheral speed of the can roll 123 is determined based on the speed reference so that the resin film F is strongly adhered to the outer peripheral surface of the can roll 123. It rotated at a speed 0.1% slower than the peripheral speed. The temperature of the can roll 123 was controlled to 60 ° C., and the temperature of the heaters 117 and 118 was controlled to 180 ° C.

The tension between the unwinding roll 114 and the winding roll 129 was 100N. A long resin film F wound around the unwinding roll 114 was set, and the tip of the resin film F was pulled out and attached to the winding roll 129 via a roll group such as a can roll 123. In this state, after evacuating the unwinding chamber 110, the plasma chamber 134, the film forming chamber 111, and the winding chamber 112 to 5 Pa with a plurality of dry pumps, further using a plurality of turbo molecular pumps and cryocoils. The air was exhausted to 3 × 10 ⁻³ Pa.

  A line-type DC ion beam irradiation apparatus was used as the ion beam irradiation apparatus 138 used for improving the adhesion between the resin film F and the nickel-chromium thin film as the underlying metal layer. In order to reduce the thermal load of the ion beam received by the resin film F, the ion film was irradiated from the ion beam irradiation device 138 while the resin film F was in close contact with the first cooling roll 136. The ion beam irradiation device 138 is connected to a DC power source (not shown), and the intensity of the ion beam can be adjusted with an ion beam voltage of 500 to 3000 V by voltage control. In this reference example, the ion beam voltage was 2000V. In the film forming apparatus for the resin film F in FIG. 3, the ion beam 2000V voltage is a process within a range in which the fragile layer of the polyimide film is removed and the polyimide itself is not deteriorated. Further, 50 sccm of oxygen gas was introduced into the ion beam irradiation apparatus 138.

  As a metal film to be formed on the resin film F, a nickel-chrome target is attached to the magnetron sputtering cathode 130 in order to form a copper thin film on a base metal layer made of a nickel-chromium thin film, and a magnetron sputtering cathode 131 is formed. A copper target was attached to ˜133. The transfer speed of the resin film F is set to 8 m / min, and the applied power to each sputtering cathode is adjusted so that a nickel-chromium thin film with a film thickness of about 10 nm and a copper thin film with a film thickness of about 100 nm thereon can be formed. did. Then, 300 sccm of argon gas was introduced into each cathode, and the film formation was started by controlling the power applied to each sputtering cathode.

  When conveyance of the long resin film F of 1000 m was completed, voltage supply to the line type DC ion beam irradiation device 138 was stopped, and supply of oxygen gas was also stopped. Subsequently, the power to the magnetron sputtering cathodes 130 to 133 was stopped, the supply of Ar gas was stopped, and the transport of the resin film F was stopped. Thereafter, the plurality of dry pumps, the plurality of turbo molecular pumps, and the cryocoil in the unwinding chamber 110, the plasma chamber 134, the film forming chamber 111, and the winding chamber 112 were stopped. Then, after introducing the atmosphere into the unwinding chamber 110, the plasma chamber 134, the film forming chamber 111, and the winding chamber 112, the resin film on which the metal film was formed was taken out.

  A part of the resin film on which the metal film is formed by the above sputtering film formation is cut out, and copper copper plating is performed thereon to thicken the copper thin film layer, and the copper clad laminate having a copper layer with a film thickness of 8 μm The test piece was obtained. In accordance with JPCA BM01-11.5.3, an initial peel strength, a heat-resistant peel strength (150 ° C. × 168 hours), and a PCT peel strength (121 ° C. × 95% × 2 atm) were applied to the test piece of this copper-clad laminate. × 100 hours). As a result, the initial peel strength was 650 N / m, the heat-resistant peel strength was 500 N / m, and the PCT peel strength was 300 N / m.

[Example 1]
A long heat-resistant resin film was formed by sputtering using a long resin film vacuum film forming apparatus (sputtering web coater) shown in FIG. 1 to produce a heat-resistant resin film with a metal film. The vacuum film forming apparatus shown in FIG. 1 is the same as the vacuum film forming apparatus of the reference example described above except that a plasma chamber 239 is provided between the ion beam chamber 234 and the film forming chamber 211. is there. In other words, unlike Example 1 described above, Example 1 was subjected to plasma treatment after ion beam treatment. Specifically, after the ion beam treatment is performed on the resin film F in the same manner as in the reference example, the ion beam treatment is performed in a state where the resin film F is wound around the second cooling roll 241 and cooled from the back side. The surface was irradiated with plasma from a plasma generator 243.

  As the plasma generator 243, a line type DC plasma generator was used, and oxygen gas was introduced thereto at 500 sccm. A DC power source (not shown) is connected to the plasma generator 243 so that the plasma intensity can be adjusted to a plasma voltage of 500 to 3000 V by voltage control. Then, the film formation was started by setting the transport speed of the resin film F to 8 m / min so that a nickel-chromium thin film having a thickness of about 10 nm and a copper thin film having a thickness of about 100 nm thereon could be formed. During the film formation, the plasma voltage was changed stepwise from 600 V to 3000 V at 200 V intervals. In addition, the conveyance distance from the start of film formation of the resin film F when the plasma voltage was changed was recorded.

  And when the long resin film F was conveyed about 500 m with the conveyance speed of 8 m / min, the conveyance speed was changed to 6 m / min. When the conveyance speed of the resin film F is set to 6 m / min, the applied power to each sputtering cathode is set so that a nickel-chromium thin film with a film thickness of about 10 nm and a copper thin film with a film thickness of about 100 nm thereon can be formed. It was adjusted. Then, the plasma voltage was changed stepwise from 600 V to 3000 V in steps of 200 V while recording the transport distance from the start of film formation of the resin film F as described above. Thus, the film-forming process was performed until 1000 m conveyance of the long resin film F was completed. When the transfer speed was 8 m / min, the total power applied to the sputtering cathode was 80 kW, and when the transfer speed was 6 m / min, the total power applied to the sputtering cathode was 60 kW. A copper clad laminate was produced in the same manner as in the reference example except for the above.

[Example 2]
A long heat-resistant resin film was used to form a heat-resistant resin film with a metal film by performing sputtering film formation on the long heat-resistant resin film using a long-film-resin vacuum film forming apparatus (sputtering web coater) shown in FIG. In the vacuum film forming apparatus shown in FIG. 2, the ion beam chamber 334 and the plasma chamber 339 are not provided with cooling rolls. Therefore, in Example 2, plasma processing and ion beam processing were performed in a floating state. A copper clad laminate was produced in the same manner as in Example 1 except for the above.

[Evaluation]
A test piece was cut out for each plasma irradiation condition changed from the resin film on which the metal film was formed in Example 1 at the conveyance speed of 8 m / min, and the film was further formed at the conveyance speed of 6 m / min. A test piece was cut out for each changed plasma irradiation condition. Electrolytic copper plating was performed on the surface of the copper thin film layer for these test pieces, so that the film thickness of the copper layer was 8 μm. The initial peel strength, heat-resistant peel strength (150 ° C. × 168 hours), and PCT peel strength (121 ° C. × 95% × 2 atm × 100 hours) were measured according to JPCA BM01-11.5.3. These peel strength data are plotted in FIGS. 4 and 5, respectively.

  From the graphs of FIGS. 4 and 5, it can be seen that as the plasma voltage increases, the heat-resistant peel strength decreases and the PCT peel strength improves. As described above, the heat-resistant resin film substrate is subjected to plasma treatment in which hydrophilic functional groups such as carboxyl groups and hydroxyl groups are introduced in the vicinity of the surface in order to improve the adhesion with the metal film. When the plasma treatment is performed, the modified layer of polyimide becomes too thick, and as a result, the base metal layer is oxidized due to oxygen contained in the modified layer. As a result, the PCT peel strength (121 ° C. × 95% × 2 It is considered that the heat-resistant peel strength (150 ° C. × 168 hours) was significantly reduced as compared to the atmospheric pressure × 100 hours.

  That is, it can be seen that the improvement in the PCT heat-resistant peel strength depends on the plasma voltage of the plasma treatment for forming the modified layer. As the plasma voltage is increased, the modified layer is gradually formed thicker, and both the increased PCT peel strength and the heat-resistant peel strength increased without degrading the polyimide itself by ion beam treatment. The optimal area to appear will appear. However, when the plasma voltage is further increased, the high heat-resistant peel strength state obtained by the ion beam treatment cannot be maintained, and the modified layer of polyimide becomes too thick due to excessive plasma irradiation. It is considered that the seed layer is oxidized by oxygen contained in the metal and the adhesion with the polyimide is reduced.

  The resin film formed in Example 2 was similarly cut out and thickened to a thickness of 8 μm, and the initial peel strength, heat-resistant peel strength, and PCT peel strength were measured. Results were obtained. From this result, it was found that the polyimide film having a thickness of 25 μm can be pretreated well even in the floating state.

F Long resin film 110 Unwinding chamber 111 Deposition chamber 112 Winding chamber 114 Unwinding roll 115, 121, 125, 128 Tension sensor roll 116 Heater box 117, 118 Heater 119, 120, 126, 127, 135, 137 Free Roll 122 Front feed roll 123 Can roll 124 Rear feed roll 129 Winding rolls 130, 131, 132, 133 Magnetron sputtering cathode 134 Ion beam chamber 136 Cooling roll 138 Ion beam irradiation device 210 Unwinding chamber 211 Film forming chamber 212 Winding chamber 214 Unwinding roll 215, 221, 225, 228 Tension sensor roll 216 Heater box 217, 218 Heater 219, 220, 226, 227, 235, 237, 2 0, 242 Free roll 222 Front feed roll 223 Can roll 224 Rear feed roll 229 Winding roll 230, 131, 132, 133 Magnetron sputtering cathode 234 Ion beam chamber 236, 214 Cooling roll 238 Ion beam irradiation device 239 Plasma chamber 243 Plasma generation Apparatus 310 Unwinding chamber 311 Film forming chamber 312 Winding chamber 313 Heat resistant resin film substrate 314 Unwinding roll 315, 321, 325, 328 Tension sensor roll 316 Heater box 317, 318 Heater 319, 320, 326, 327, 335, 337, 340, 342 Free roll 322 Front feed roll 323 Can roll 324 Rear feed roll 329 Winding roll 330, 331, 332, 33 Magnetron sputtering cathodes 334 ion beam chamber 338 ion beam irradiation apparatus 339 plasma chamber 343 plasma generator

Claims (7)

A surface treatment method before forming a film on a resin film by a dry plating method in a reduced pressure atmosphere, wherein at least one surface of the resin film is irradiated with an ion beam having an ion beam voltage of 600 to 3000 V (excluding 3000 V). After removing the fragile layer on the surface of the resin film by performing a treatment, a treatment is performed to irradiate the same surface with plasma. In the treatment with plasma, the correlation between the plasma voltage and the peel strength obtained in advance In the relationship, the plasma voltage is higher than the plasma voltage when the PCT peel strength starts to decrease when the plasma voltage is lowered, and within the range below the plasma voltage when the heat resistant peel strength starts decreasing when the plasma voltage is increased. The surface treatment method of the resin film characterized by applying the plasma voltage of this . The resin film surface treatment method according to claim 1 , wherein an atmosphere of the treatment of irradiating the ion beam and an atmosphere of the treatment of irradiating the plasma are different from each other. The surface treatment method for a resin film according to claim 1 or 2 , wherein the resin film is a long resin film conveyed by roll-to-roll. The surface treatment of a resin film according to claim 3 , wherein the long resin film is cooled from a surface opposite to a surface to be irradiated during the ion beam irradiation and the plasma irradiation. Method. A method for forming a film on a long resin film under a reduced pressure atmosphere, wherein the surface of the long resin film is subjected to surface treatment by the surface treatment method according to claim 3 or 4 on the surface of the long resin film. A film forming method comprising forming a film on a treated surface by a dry plating method. A method for producing a copper clad laminate having a laminate structure by forming a base metal layer on the surface of a long resin film without using an adhesive, and forming a copper layer on the surface of the base metal layer,
The surface of the long resin film is subjected to a surface treatment by the surface treatment method according to claim 3 or 4 , and then the base metal layer and the copper layer are sequentially applied to the surface subjected to the surface treatment of the long resin film. A method for producing a copper clad laminate, which is formed by a dry plating method. The method for producing a copper-clad laminate according to claim 6 , wherein the dry plating method is a sputtering method.

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