JP2014053410A - Production method and production apparatus of double side metal laminate film, and manufacturing method of flexible double side printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a double side metal laminate film in which the surface of an insulating film is not wrinkled, and excellent adhesion is ensured between the insulating film and a copper clad layer, even if an insulating film having a thickness of 20 μm or less is used.SOLUTION: A first surface treatment step of irradiating one surface of an insulating film 1 with an ion beam, a second surface treatment step of irradiating the other surface of an insulating film 1 with an ion beam, a first dry deposition step of sequentially depositing a base metal layer 2b and a copper thin film layer 3b, by dry plating method, on any one surface of the insulating film 1 subjected to surface treatment, and a second dry deposition step of sequentially depositing a base metal layer 2a and a copper thin film layer 3b, by dry plating method, on the surface of the insulating film where the copper thin film layer is not deposited, are performed sequentially.

Description

  The present invention relates to a method and an apparatus for producing a double-sided metal laminate film, which is used in a flexible double-sided printed wiring board and has a copper coating layer formed on both sides of an insulating film without using an adhesive. Moreover, this invention relates to the manufacturing method of the flexible double-sided printed wiring board using this double-sided metal laminated film.

  In recent years, electronic devices represented by televisions, mobile phones, notebook computers, digital cameras, game machines, and the like have been rapidly reduced in size, thickness, and weight, and the materials used for these devices are also small. There is a demand for high-density, high-performance materials that can store parts in the space. As a material that meets such requirements, flexible double-sided printed wiring boards that are thin and can be folded into narrow spaces and have excellent bending resistance have been widely used. However, for flexible double-sided printed wiring boards (flexible circuit boards) that are used in movable parts such as foldable mobile phones and sliding mobile phones, which have high demands for higher density, further narrower pitch and better performance Flexibility is required. The conventional flexible double-sided printed circuit board structure has the problem of causing disconnection after a long period of use when it is multi-layered or applied to a place with a smaller bending radius, and such high bending resistance is obtained. It has not been possible to provide a flexible double-sided printed wiring board with sufficient performance for the required applications. Therefore, in order to realize even higher bending resistance, it is required to further thin the flexible double-sided printed wiring board. Currently, the thickness of the insulating film constituting the board is about 20 μm or less. Research and development is actively underway.

  As a material of the flexible double-sided printed wiring board, a three-layer metal laminated film in which a copper foil as a conductor layer is bonded onto an insulating film using an adhesive as disclosed in JP-A-6-132628. A double-sided metal laminated film to which the structure is applied has been used. However, in the structure of this three-layer metal laminated film, side etching in which etching proceeds not only in the direction perpendicular to the substrate surface but also in the plane direction (side wall surface) during etching to obtain a desired wiring pattern. As a result, the cross-sectional shape of the wiring part tends to be a trapezoid with a flared base. As a result, there is a problem that it is difficult to narrow the wiring pattern pitch. Moreover, in this structure, since copper foil is bonded together on the surface of an insulating film through an adhesive layer, there is also a problem that it is difficult to thin the conductor layer with this copper foil.

  On the other hand, as a material for a flexible double-sided printed wiring board, a conductive layer is formed by a dry plating method or a wet plating method without using an adhesive on the insulating film instead of the structure of the three-layer metal laminated film. It is becoming mainstream to use a double-sided metal laminate film to which a structure of a two-layer metal laminate film that directly forms a copper coating layer is applied.

  As a method for forming such a two-layer metal laminated film, for example, Japanese Patent Laid-Open No. 8-139448 describes that a copper coating layer having a uniform thickness is formed on an insulating film by electroplating. ing. In this method, before the copper coating layer is formed by electroplating, a metal other than copper, such as chromium, chromium oxide, or nickel, is formed on the insulating film by a dry plating method such as vacuum deposition, sputtering, or ion plating. After the base metal layer made of about 50 to 200 mm is formed, a thin copper layer by dry plating and an electroless copper plating film by electroless plating are sequentially formed.

  Japanese Patent Laid-Open No. 6-120630 discloses a nickel method by sputtering from the viewpoint of enabling formation of a fine wiring pattern with a single etching solution while maintaining the adhesion between the insulating film substrate and the copper layer. It is shown that a base metal layer made of a nickel-chromium alloy having a content of 5 at% to 80 at% is formed.

  However, in any two-layer metal laminated film, since the anchor effect by the base metal layer cannot be sufficiently obtained, there is a problem that the adhesion between the insulating film and the base metal layer becomes weak.

  Regarding the improvement of the anchor effect, Japanese Patent Laid-Open No. 5-251843 discloses that a polyimide film is exposed to a glow discharge of a gas containing nitrogen oxide for a short time in order to improve the surface properties of the polyimide film which is an insulating film. It is disclosed that after the exposure, a base metal layer is continuously formed of an ultra-thin nickel-copper alloy film while maintaining a vacuum state. However, in the surface treatment of the insulating film by glow discharge, the anchor effect by the base metal layer is not sufficiently obtained.

As the surface treatment of such an insulating film, a plasma treatment method, an ion beam treatment method, and the like are also known. For example, Japanese Patent Application Laid-Open No. 2006-49893 discloses an ion beam processing method in which an ion beam is irradiated using an oxygen (O ₂ ) -argon (Ar) mixed gas. As described above, when the ion beam treatment method is used for the surface treatment of the insulating film, the adhesion between the insulating film and the base metal layer can be improved.

  In addition, when producing a double-sided metal laminated film by applying such a structure of a two-layer metal laminated film, as disclosed in JP-A-5-251843, one surface of the insulating film is modified, Usually, after forming a base metal layer and forming a copper thin film thereon, the other surface of the insulating film is modified to form a base metal layer and forming a copper thin film thereon. Yes.

JP-A-6-132628 Japanese Patent Laid-Open No. 8-139448 JP-A-6-120630 JP-A-5-251843 JP 2006-49893 A

  However, when a double-sided metal laminate film is to be manufactured using an ion beam treatment method as the surface treatment of the insulation film, it is possible to improve the adhesion between the insulation film and the base metal layer, but the double-sided metal laminate Wrinkles may occur on the surface of the insulating film forming the film. In particular, this tendency becomes prominent when an insulating film having a thickness of 20 μm or less is used for further thinning of the flexible double-sided printed wiring board, which causes a decrease in the yield of the flexible double-sided printed wiring board. ing.

  In view of the above-described problems, the object of the present invention is to form a base metal layer on both surfaces of an insulating film and to form a copper coating layer on both base metal layers in the production of a double-sided metal laminated film. In this case, an object of the present invention is to provide a method for producing a double-sided metal laminate film that ensures sufficient adhesion between the insulating film and the copper coating layer and that does not cause wrinkles in the insulating film.

  In view of such circumstances, as a result of intensive studies by the present inventors, after forming a base metal layer on both surfaces of the insulating film by a dry plating method, a copper coating layer is formed on the surface of the base metal layer. In the method for manufacturing a double-sided metal laminated film, after performing surface treatment on both sides of the insulating film by sequentially irradiating both sides of the surface of the insulating film, a base metal layer and copper are formed on both sides of the insulating film. By sequentially forming a thin film layer, a flexible double-sided printed wiring board having no wrinkles and sufficient adhesion can be obtained even when the insulating film having a thickness of 20 μm or less is used. The knowledge that it can be obtained was acquired. The present invention has been made based on such knowledge.

That is, in the method for producing a double-sided metal laminated film of the present invention, a base metal layer is formed by a dry plating method on both sides of an insulating film without using an adhesive, and then a copper film layer is formed on the surface of the base metal layer. When doing
(1) As a first surface treatment step, one surface of the insulating film is irradiated with an ion beam,
(2) After the first surface treatment step, as the second surface treatment step, the other surface of the insulating film is irradiated with an ion beam,
(3) After the second surface treatment step, as the first dry film formation step, one of the base metal layer and the copper coating layer is formed on any surface of the surface-treated insulating film by a dry plating method. The copper thin film layer constituting part or all of the film is sequentially formed,
(4) After the first dry film forming process, as the second dry film forming process, the base metal layer and the copper are formed on the surface of the insulating film on which the copper thin film layer is not formed by dry plating. A copper thin film layer constituting part or all of the coating layer is sequentially formed,
It is characterized by that.

  The present invention is suitably applied when the insulating film having a thickness of 20 μm or less is used.

  Preferably, in the ion beam irradiation in the first surface treatment step and the second surface treatment step, any one of argon, nitrogen, oxygen, or at least two mixed gases selected from these groups is used.

  In this case, the manufacturing method of the present invention uses a roll-to-roll film processing apparatus equipped with an ion gun that can irradiate the insulating film with the first surface treatment step and the second surface treatment step from one direction. Can be done.

  In addition, it is preferable to suppress the temperature rise of the insulating film before the 1st surface treatment process and after the 2nd surface treatment process to 50 degrees C or less.

  As the dry plating method, it is preferable to apply a sputtering method.

  Insulating films applicable to the present invention include polyimide films, polyamide films, polyester films, polytetrafluoroethylene films, polyfinylene sulfide films, polyethylene naphthalate films, and liquid crystal polymer films. It can be illustrated.

  As the base metal layer, it is preferable to use a nickel-chromium alloy containing chromium in a range of 15% by mass to 25% by mass.

  Moreover, it is preferable to form the said copper coating layer so that film thickness may be in the range of 0.01 micrometer-35 micrometers.

  If necessary, after the second dry film forming process, a wet film forming process for forming a copper plating layer on both surfaces of the copper thin film layer together with the copper thin film layer by a wet plating method. Can further be provided.

  In order to manufacture the double-sided metal laminated film of the present invention, a double-sided metal laminated film manufacturing apparatus including a vacuum chamber and a roll-to-roll film processing apparatus disposed in the vacuum chamber can be used.

Among these, the roll-to-roll film processing apparatus includes an unwinding roll, a winding roll, and a film track between these rolls,
A first ion gun that irradiates one surface of the insulating film with an ion beam;
A second ion gun disposed downstream of the first ion gun on the opposite side of the first ion gun across the film trajectory and irradiating the other surface of the insulating film with an ion beam;
The base metal layer and a copper thin film layer constituting a part or all of the copper coating layer are sequentially formed on any surface of the insulating film disposed on the downstream side of the second ion gun and subjected to a surface treatment. A first dry film forming apparatus for forming a film;
On the downstream side of the first dry film forming apparatus, disposed on the opposite side of the first dry film forming apparatus across the film trajectory, and on the surface of the insulating film on which the copper thin film layer is not formed, A second dry film forming apparatus for sequentially forming a base metal layer and a copper thin film layer constituting part or all of the copper coating layer;
Is provided.

  The flexible double-sided printed wiring board of the present invention can be obtained by wiring the double-sided metal laminated film produced by the production method by a subtractive method or a semi-additive method.

  According to the manufacturing method of the present invention, even when an insulating film having a thickness of 20 μm or less is used, the surface of the insulating film is not wrinkled during the surface treatment, and the insulating film It is possible to obtain a double-sided metal laminate film excellent in adhesion between the copper coating layer and the copper coating layer with a high yield.

  About the double-sided metal laminated film obtained by this invention, it is possible to obtain a flexible double-sided printed wiring board by the wiring process by a subtractive method or a semiadditive method. Such a flexible double-sided printed wiring board with a small thickness can be applied with high bending resistance to a movable part such as a foldable mobile phone or a sliding mobile phone, which has a high demand for high density.

FIG. 1 is a flowchart showing the steps of the present invention. FIG. 2 is a schematic view of a continuous sputtering apparatus for carrying out the method for producing a double-sided metal laminated film of the present invention.

1. Manufacturing method of double-sided metal laminated film The manufacturing method of the double-sided metal laminated film of the present invention is a method of forming a base metal layer made of a nickel alloy by dry plating without using an adhesive on both sides of an insulating film, It is a manufacturing method of the double-sided metal laminated film which forms a copper coating layer on the surface.

  In particular, the method for producing a double-sided metal laminated film of the present invention includes a first surface treatment step of irradiating one surface (1a) of an insulating film (1) with an ion beam, as shown in FIG. After the step, a second surface treatment step of irradiating the other surface (1b) of the insulating film (1) with an ion beam, and a second surface treatment step followed by a first surface treatment step and a second surface treatment step, A copper thin film layer (3b) constituting part or all of the underlying metal layer (2b) and the copper coating layer is sequentially formed on the surface (1b) of the surface-treated insulating film (1) by dry plating. After the first dry film forming step and the first dry film forming step, the base metal layer is formed on the surface (1a) of the insulating film (1) where the copper coating layer is not formed by dry plating. (2a) and part or all of the copper coating layer And a second dry film forming step of sequentially depositing a copper thin film layer (3a).

  In addition, in the manufacturing method of the double-sided metal laminated film of this invention, after performing surface treatment by irradiation of an ion beam to the surface (1a, 1b) of both sides of an insulating film (1), a base metal layer (2a, 2b) and The copper thin film layers (3a, 3b) may be formed, and the order of the surfaces on which the films are formed is not limited. That is, the films may be formed in the order shown in FIG. 1 or after both surface (1a, 1b) of the insulating film (1) is subjected to surface treatment by ion beam irradiation, After a base metal layer (2a) and a copper thin film layer (3a) are formed on one surface (1a) by a dry plating method, a base metal layer is formed on the other surface (1b) of the insulating film by a dry plating method. (2a) and a copper thin film layer (3a) may be formed.

(1) Surface treatment process Hereinafter, a 1st surface treatment process and a 2nd surface treatment process are demonstrated in detail among the manufacturing methods of the double-sided metal laminated film of this invention. As described above, the first surface treatment step and the second surface treatment step include a first surface treatment step of irradiating one surface (1a) of the insulating film (1) with an ion beam, and a first surface treatment step. Later, the second surface treatment step of irradiating the other surface (1b) of the insulating film (1) with an ion beam (see FIG. 1).

  As in the conventional method for producing a double-sided metal laminated film described in JP-A-5-251843, the surface treatment and the formation of a base metal layer and a copper thin film layer on one surface of an insulating film After performing the surface treatment and film formation of the base metal layer and the copper thin film layer on the other surface of the insulating film, when performing the surface treatment and film formation on the other surface, The mechanical load due to the surface treatment is not alleviated, and there is a possibility that problems such as wrinkles occur on the surface. Such a tendency starts to appear when an insulating film having a thickness of 40 μm or less is used, and becomes particularly prominent when a film having a thickness of 20 μm or less is used. On the other hand, in this invention, after surface-treating with respect to the surface of the both sides of an insulating film, the base metal layer and the copper thin film layer are formed into each of the surface after these surface treatments. For this reason, the mechanical load due to the irradiation of the ion beam is relieved, and even when an insulating film having a thickness of 20 μm or less is used, the generation of wrinkles can be prevented and sufficient adhesion can be achieved. The double-sided metal laminate film can be obtained.

(Insulating film)
The insulating film that can be used in the method for producing a double-sided metal laminate film of the present invention can be used without particular limitation as long as it is an insulating film that is used in the production of a general flexible circuit board. . Preferably, polyimide film, polyamide film, polyester film such as polyethylene terephthalate (PET) or polyethylene terephthalate (PEN), polytetrafluoroethylene film, polyphenylene sulfide film, polyethylene naphthalate film, liquid crystal polymer film One insulating film selected from the group of films is used. In particular, considering the heat resistance, dielectric properties, electrical insulation, flexible double-sided printed wiring board manufacturing process and chemical resistance in the next process, etc. required for flexible double-sided printed wiring board It is more preferable to select appropriately.

  As such an insulating film, specifically, polyimide films include Kapton (registered trademark) manufactured by Toray DuPont Co., Ltd., Upilex (registered trademark) manufactured by Ube Industries, Ltd., Apical manufactured by Kaneka Corporation ( Registered trademark), XENO (registered trademark) manufactured by Toyobo Co., Ltd., and the like. Examples of the aramid film that is an aromatic polyamide film include Mikutron (registered trademark) manufactured by Toray Industries, Inc., and Aramica (registered trademark) manufactured by Teijin Advanced Film Co., Ltd.

  In the present invention, the above-described effects can be obtained by the application of the double-sided metal laminated film having a thickness of 40 μm or less as an insulating film that has been used conventionally. In the production of a double-sided metal laminated film using an insulating film having a thickness of 20 μm or less, further 15 μm or less, which is thinner than the above, wrinkles can be prevented from occurring on the surface of the insulating film due to surface treatment. And in the obtained double-sided metal laminated film, the high adhesiveness between the insulating film and the copper coating layer as a conductor layer can be achieved.

(Ion beam irradiation)
Known surface treatment methods for insulating films include plasma treatment and ion beam treatment. Among these, the ion beam processing method is different from the plasma processing method in that the directivity is high, only ions are emitted, and the energy density of the irradiated part is high. That is, in the plasma processing method, when the insulating film is surface-treated, the insulating film passes through the plasma atmosphere, so that there is a possibility that the film is damaged by the plasma and the film strength is lowered. is there. On the other hand, in the ion beam processing method, since the insulating film does not pass through the plasma at the ion beam generation site, such a problem does not occur. In addition, the plasma processing method requires time for processing, and is not suitable for continuous processing using a roll-to-roll film processing apparatus, which will be described later. However, the ion beam processing method can perform surface processing in a short time. Is possible. For these reasons, in the present invention, an ion beam treatment method is employed as the surface treatment of the insulating film.

  As an ion beam processing method, an ion implantation method (ion implantation) in which ionized atoms or molecules collide with an insulating film while being accelerated at a high energy of several tens keV to several MeV, and these ions enter the insulating film. And an ion beam irradiation method (ion irradiation) in which an uneven surface is formed on the surface of the insulating film.

  In the ion beam processing method, when the surface of an insulating film is irradiated with an ion beam, the gas released from the ion gun is accelerated and at the same time a voltage is applied to the insulating film to be subjected to the surface treatment, generating from the ion gun. An attractive force or repulsive force is formed between the ions and the sample surface, and charge deformation is performed, thereby causing a change in the chemical bonding state of molecules on the surface of the insulating film. In addition, since the ion beam has high directivity, a fresh interface on the surface of the insulating film appears due to ion collision, and as a result, high adhesion can be realized with the metal layer formed thereafter. For example, when polyimide is used for the insulating film, a part of the imide ring is opened and an amide bond is formed, so that high adhesion is realized between the insulating film and the metal layer.

In the surface treatment process of the present invention, the energy of ion particles is set to 0.01 keV to 1 keV by selecting the discharge voltage, discharge current, discharge power, beam gas flow rate, ion gun quality pressure, film feed rate, etc. It is preferable. The irradiation amount is preferably 10 ¹² ions / cm ² to 10 ¹⁶ ions / cm ² . When the energy of the ion particles is less than 0.01 keV, or when the irradiation amount is less than 10 ¹² ions / cm ² , the surface treatment is not sufficiently performed. On the other hand, when the energy of the ion particles exceeds 1 keV, or when the irradiation dose exceeds 10 ¹⁶ ions / cm ² , the film receives too much damage, which causes problems such as a reduction in strength and breakage of the film. Appropriate treatment conditions for the insulation film depend on various conditions such as the output of the ion gun that performs surface treatment by ion beam irradiation, differences in the ion gun equipment, gas pressure of the ion gun, thickness and width of the insulation film, and conveyance speed. Is different. Appropriate processing conditions may be selected from the characteristics required for the obtained double-sided metal laminated film and the temperature change of the thermal load on the insulating film by ion beam processing. Such processing conditions were preliminarily tested. Preferably selected above.

In the surface treatment by ion beam irradiation according to the present invention, the gas released from the ion gun is argon (Ar), oxygen (O ₂ ), nitrogen (N ₂ ), or at least two selected from these groups. A mixed gas is preferably used, and argon (Ar) is particularly preferably used from the viewpoint of preventing gas contamination.

  In the surface treatment of the insulating film by ion beam irradiation, the temperature rise of the insulating film before the first surface treatment step and after the second surface treatment step is 50 ° C. or less, preferably 30 ° C. or less. It is preferable to adjust. When the temperature rise of an insulating film exceeds 50 degreeC, it may become a cause of malfunctions, such as generating a wrinkle in an insulating film. The regulation of the temperature rise of the insulating film can be performed, for example, by cooling the film being processed with a cooling roll or the like.

(2) Dry film forming step After surface treatment by irradiation of ion beam is performed on both surfaces (1a, 1b) of the insulating film (1), the base metal layer (2a, 2b) and the copper thin film are formed by dry plating. Layers (3a, 3b) are formed.

(Dry plating method)
As the dry plating method, a vacuum deposition method, a sputtering method, a CVD method, or the like can be used. In the present invention, it is preferable to form the base metal layer and the copper thin film layer by sputtering from the viewpoint of easy handling, productivity, and cost.

The sputtering conditions when the sputtering method is employed are appropriately selected. For example, a polyimide resin having a thickness of 10 μm to 20 μm is used as the insulating film, and a nickel alloy having a thickness of about 0.01 μm to 10 μm is used. In the case where the underlying metal layer and the copper thin film layer are continuously formed, it is preferable to form the film at an ultimate vacuum of 1 × 10 ⁻¹ Pa or less and a sputtering gas pressure of 0.5 Pa to 5.0 Pa. Note that other conditions such as input power vary depending on the type, size, or target film thickness of the target, and therefore it is preferable to select them appropriately after conducting a preliminary test or the like. The sputtering conditions are the same in the first dry film forming process and the second dry film forming process.

(Underlying metal layer)
The base metal layer contributes to improvement in adhesion between the insulating film and the copper coating layer and insulation reliability of the flexible double-sided printed wiring board. As such a base metal layer, a chromium alloy, a nickel alloy, or the like can be used. In particular, in the present invention, a nickel-chromium alloy, a nickel-chromium-molybdenum alloy, a nickel-vanadium alloy, or the like can be used as the base metal layer, and among these, the chromium content is 15 mass% to 25 mass%. It is preferable to use a nickel-chromium alloy having a range, and it is more preferable to use a nickel-chromium alloy having a chromium content in the range of 15% by mass to 22% by mass. When the chromium content is less than 15% by mass, there is a problem that the insulation reliability is lowered. When the chromium content is more than 25%, it is difficult to form a wiring pattern.

  The film thickness of the underlying metal layer is appropriately selected from the metal type and composition of the underlying metal layer, and the film thickness from the flexible double-sided printed wiring board and wiring processability, adhesion and insulation reliability required for wiring. However, in the present invention, the thickness is preferably 3 nm to 40 nm, more preferably 7 nm to 40 nm, and even more preferably 10 nm to 40 nm. If the thickness of the underlying metal layer is less than 3 nm, the adhesion between the insulating film and the copper coating layer cannot be made sufficient, and if it exceeds 40 nm, the thickness of the obtained flexible double-sided printed wiring board The thickness cannot be thinned sufficiently.

(Copper thin film layer)
The copper thin film layer constitutes part or all of the copper coating layer that becomes the wiring of the flexible double-sided printed wiring board by wiring processing. The copper thin film layer is formed on the surface by a dry plating method such as a sputtering method after the base metal layer is formed. The film thickness of the copper thin film layer formed by this dry plating method is preferably 0.01 μm to 1 μm, more preferably 0.03 μm to 0.7 μm, and still more preferably 0.05 μm to 0.35 μm. If the film thickness of the copper thin film layer is less than 0.01 μm, the underlying metal layer generates heat when performing copper electroplating described later, which may cause problems such as discoloration of the copper electroplating coating layer. On the other hand, since the film formation rate by the dry plating method is slower than the film formation rate by the electroplating method, if the film formation exceeds 1 μm by the dry plating method, the productivity is lowered.

(3) Wet film formation process The film thickness of the copper coating layer of the double-sided metal laminate film depends on the choice of the wiring method of the flexible double-sided printed wiring board, that is, the subtractive method or the semi-additive method. is there. When a wiring pattern is formed by the semi-additive method, a copper film layer thickness of about 1 μm is sufficient. Therefore, even if the copper film layer is formed only by a dry film forming process, productivity is deteriorated. Does not occur. However, when a wiring pattern is formed by a subtractive method, a copper coating layer having a film thickness exceeding 1 μm may be required. In such a case, the copper coating layer is formed only by a dry film forming process. It is conceivable that the productivity is remarkably reduced due to the film formation rate when it is formed. Therefore, in the present invention, when the copper coating layer is to be formed on the surface of the base metal layer with a thickness exceeding 1 μm, it is preferable to further include a wet film forming step, and such wet film forming is performed by electroplating. More preferably.

  The film thickness of the copper coating layer is preferably in the range of 0.01 μm to 35 μm, more preferably in the range of 0.3 μm to 15 μm, and even more preferably in the range of 0.3 μm to 12 μm. If the film thickness of the copper coating layer is less than 0.01 μm, a problem may easily occur in the electrical conductivity of the wiring portion, and a problem in strength may occur. On the other hand, if the film thickness exceeds 35 μm, hair cracking or warping may occur and adhesion may be reduced, and the influence of side etching may be increased, making narrow pitching difficult. In addition, it does not specifically limit as an electroplating method, For example, a well-known electroplating method can be used in copper sulfate aqueous solution.

(4) Manufacturing apparatus of double-sided metal laminated film In the present invention, the first surface treatment step and the second surface treatment step are roll-to-roll film treatment provided with an ion gun that can irradiate the insulating film from one direction. Preferably it is performed by an apparatus. Furthermore, in the present invention, in the continuous sputtering apparatus provided with the sputtering apparatus, all of the first surface treatment process, the second surface treatment process, the first dry film formation process, and the second dry film formation process can be performed continuously. It is preferable to do.

  As an example for carrying out such a production method of the present invention, a schematic view of a continuous sputtering apparatus (4) is shown in FIG. The continuous sputtering apparatus (4) includes a vacuum chamber (5) and a roll-to-roll film processing apparatus disposed in the vacuum chamber (5). This roll-to-roll film device comprises an unwinding roll (6), a winding roll (7), and a film track between these rolls.

  This roll-to-roll film processing apparatus irradiates one surface of an insulating film (1) with an ion beam between an unwinding roll (6) and a winding roll (7). (9a) on the downstream side of the first ion gun (9a) and on the opposite side of the first ion gun (9a) across the film trajectory, the other surface of the insulating film (1) is irradiated with an ion beam The base metal layer (2b) and the copper thin film layer are disposed on any surface of the second ion gun (9b) and the surface of the insulating film (1) that is disposed on the downstream side of the second ion gun (9b). (3b) and the first dry deposition apparatus (70), and the first dry deposition apparatus (70) on the downstream side of the first dry deposition apparatus (70) with the film trajectory in between. Is placed on the opposite side, copper thin film of insulating film (1) There are sequentially deposited surface serial underlying metal layer on the side not formed with (2a) a copper thin-film layer (3a), comprising at least a second dry film forming device (71).

  The insulating film (1) unwound from the unwinding roll (6) is conveyed to the heater (8) through the guide roll (10) and dried by the heater (8) that heats it. Thereafter, the insulating film (1) is conveyed in front of the first and second ion guns (9a, 9b) via the tension sensor roll (20) and the guide roll (11), and both side surfaces (1a, 1b) thereof. Surface treatment is performed by irradiating an ion beam to the ion gun (9a, 9b) (first and second surface treatment steps). In addition, when using a cooling roll in order to make the temperature rise of the insulating film before the 1st surface treatment process and the 2nd surface treatment process into 50 degrees C or less, for example, the 1st ion gun (9a) and the 1st It is preferable to arrange a cooling roll between the two ion guns (9b), and it is more preferable to use a guide roll (11) having a function as a cooling roll.

  As described above, the insulating film (1) is first subjected to surface treatment on both side surfaces (1a, 1b), and then the first dry film forming apparatus (70) through the guide roll (12) and the feed roll (30). ). In the first dry-type film forming apparatus (70), the base metal layer (2b) and the copper thin film are formed on the cooling can roll (40) by the sputtering method using the sputtering cathode (50, 51) on the surface (1b). The layer (3b) is formed (first dry film forming step).

  Furthermore, it is conveyed to a 2nd dry-type film-forming apparatus (71) through a guide roll (13), a tension sensor roll (21), a guide roll (14-16), and a feed roll (31). In the second dry film forming apparatus (71), the base metal layer (2a) and the copper thin film are formed on the cooling can roll (41) by the sputtering method using the sputtering cathode (60, 61) on the surface (1a). The layer (3a) is formed (second dry film forming step).

  In this way, the insulating film (1) is formed with the base metal layer (2a, 2b) and the copper thin film layer (3a, 3b) on both side surfaces (1a, 1b), and then the guide roll (17), tension It is wound up by a winding roll (7) through a sensor roll (22) and a guide roll (18).

In the continuous sputtering apparatus (4) as shown in FIG. 2, the shape of the vacuum chamber (5) is not limited, but it is necessary to be able to maintain a reduced pressure in the range of 10 ⁻⁴ Pa to 1 Pa. Further, as the unwinding roll (6) and the winding roll (7), those capable of maintaining the balance of the tension of the insulating film (1) by torque control using a powder clutch or the like are used. Further, as the cooling can roll (40, 41) and the feed roll (30, 31), those provided with power by a servo motor are used. Further, as the tension sensor roll (21) and the guide rolls (16, 18), those having a function as a drive roll are used.

  A partition is provided between the unwinding roll (6) and the guide roll (10), between the guide roll (12) and the feed roll (30), and between the guide roll (16) and the feed roll (31). It is also possible to change the atmosphere in each step by dividing the atmosphere of the take-out roll (6), ion gun (9a, 9b), sputtering cathode (50, 51), and sputtering cathode (60, 61).

2. Manufacturing method of flexible double-sided printed wiring board A flexible double-sided printed wiring board can be manufactured by wiring a double-sided metal laminate film by a subtractive method or a semi-additive method. Since these detailed methods are the same as those of the prior art, detailed description is omitted here. In addition, since the film thickness of a copper coating layer needs the film thickness equivalent to the film thickness of wiring, when carrying out wiring processing by a subtractive method, as mentioned above, it is further wet after a dry-type film-forming process. A film forming process may be required. On the other hand, in the case of wiring processing by the semi-additive method, the film thickness is only required to ensure the conductivity necessary for electrodeposition, and further, the portion unnecessary for wiring is considered to be removed by soft etching. Is enough. For this reason, there is no problem even if only the dry film forming step, but from the viewpoint of ensuring the reliability and higher strength of the electrical conductivity of the wiring portion, when forming a copper film layer of 1 μm or more, It is also possible to combine both the dry film forming process and the wet film forming process.

  Moreover, in the flexible double-sided printed wiring board, the thinner the insulating film, the more advantageous from the viewpoints of flexibility and workability of through holes. This is because the displacement of the wiring patterns on both sides due to the thin insulating film can be reduced, and through holes are formed by etching an insulating film such as polyimide with a chemical solution. In this regard, according to the method for manufacturing a flexible double-sided printed wiring board according to the present invention, an insulating film having a thickness of 20 μm or less can be used, compared with an insulating film having a thickness of about 40 μm that has been conventionally required. It can be said that it is extremely advantageous in bending resistance.

  Although through holes can be drilled with a laser or the like, burrs are generated in the processed part due to laser processing, and it is necessary to add a process for removing these burrs. The problem of rising.

1. Hereinafter, the present invention will be described in more detail with reference to examples. In the following Examples and Comparative Examples, (a) determination of wrinkles and (b) measurement of peel strength (peeling strength) were performed by the following methods.

(A) Judgment of wrinkles It was performed by visually observing the surface of the double-sided metal laminated film in a state of being taken out from the sputtering apparatus. As for the results of this observation, in Table 1, good wrinkles were not found, and fine wrinkles that did not affect the performance of the double-sided metal laminated film were found slightly (◯), Those in which wrinkles to the extent that they affect the performance of the double-sided metal laminated film were found were expressed as defective (x).

(B) Measurement of peel strength Initial peel strength was measured by a measuring method based on IPC-TM-650 and NUMBER 2.4.9. The measurement conditions at this time were such that the peel angle was 90 °. The wiring pattern was formed by a subtractive method. Specifically, the lead width of the sample is 1 mm, and a photosensitive resist (manufactured by Tokyo Ohka Kogyo Co., Ltd., PMERP-RH30PM) is applied to the surface of the copper coating layer of the double-sided metal laminated film to form a pattern with a width of 1 mm. So exposed. Thereafter, the film was developed with an aqueous sodium carbonate solution having a concentration of 0.3% by mass, immersed in a ferric chloride solution (specific gravity 40 ° Baume, temperature 43 ° C.) for 2 minutes, washed with water, and dried. Thereafter, the resist was peeled off using an aqueous sodium hydroxide solution having a concentration of 4% by mass.

  Also, the heat-resistant peel strength is the same as the initial peel strength. After holding the sample at 150 ° C. for 168 hours, taking it out and cooling it to room temperature, the peel angle is 90 ° as with the initial peel strength. The strength was measured.

  Table 1 shows that both the initial peel strength on both surfaces (1a, 1b) of the obtained double-sided metal laminate film and the peel strength after the heat test (heat peel strength) are 400 N / m or more. As a result, when there were those less than 400 N / m, they were expressed as defective (x).

Example 1
As the insulating film (1), a polyimide film (4 ton) manufactured by Toray DuPont Co., Ltd. having a thickness of 12.5 μm was used, and the polyimide film ( After performing surface treatment on both surfaces (1a, 1b) of 1), a base metal layer (2a, 2b) and a copper thin film layer (3a, 3b) are formed on both surfaces (1a, 1b). Filmed.

Specifically, the polyimide film (1) is placed in a continuous sputtering apparatus (4), the apparatus (4) is evacuated to 1 × 10 ⁻¹ Pa, and then the polyimide film is removed by an infrared heater (8). Heat was applied to remove moisture in the film. Then, the surface of one surface (1a) of the polyimide film (1) was surface-treated by evacuating to 1 × 10 ⁻⁴ Pa and irradiating an ion beam with a first ion gun (9a) (anode layer source type). After (first surface treatment step), the other surface (1b) of the polyimide film (1) was surface treated by irradiating an ion beam with the second ion gun (9b) (second surface treatment step). At this time, the gas type used was nitrogen gas (N ₂ ). In this example, as a result of using a guide roll (11) having a function as a cooling roll, the temperature rise of the insulating film before the first surface treatment step and after the second surface treatment step was 30. ° C.

  After the second surface treatment step, the polyimide film (1) is transported to the sputtering apparatus (70), and a Ni-20 mass% Cr alloy is mounted on the sputtering cathode (50) as a target, and the sputtering cathode (51). A Cu target was mounted, and a base metal layer (2b) and a copper thin film layer (3b) were formed by sputtering (first dry film forming step). Thereafter, the polyimide film (1) is conveyed to the sputtering device (71), and a Ni-20 mass% Cr alloy is mounted on the sputtering cathode (60) as a target, and a Cu target is mounted on the sputtering cathode (61). The base metal layer (2a) and the copper thin film layer (3a) were formed by sputtering (second dry film forming step). At this time, the thickness of the base metal layer (2a, 2b) was 10 nm, and the thickness of the copper thin film layer (3a, 3b) was 0.1 μm.

  After the second dry film-forming step, the obtained double-sided metal laminated film was taken out from the continuous sputtering apparatus (4), and the surface was visually checked for (a) wrinkles. As a result, generation of wrinkles was not confirmed. .

  Thereafter, a copper plating layer having a thickness of 8 μm was formed on both side surfaces of the obtained double-sided metal laminated film by electroplating using an aqueous sulfuric acid copper sulfate solution. The obtained double-sided metal laminate film was measured for (b) peel strength, and the initial peel strength and heat-resistant peel strength were evaluated.

(Examples 2 to 7)
A double-sided metal laminated film was obtained in the same manner as in Example 1 except that the gas type used for the surface treatment by ion beam irradiation was changed (Examples 2 to 7). Table 1 shows the determination results of (a) wrinkles and (b) peel strength.

(Examples 8 and 9)
The gas type used for the surface treatment by ion beam irradiation was changed to only argon gas (Ar), and the film thickness of the base metal layer (2a, 2b) was 20 nm in Example 8, and 30 nm in Example 9. A double-sided metal laminated film was obtained in the same manner as in Example 1 except for the above (Examples 8 and 9). Table 1 shows the determination results of (a) wrinkles and (b) peel strength.

(Examples 10 and 11)
In Example 10, Ni-10 mass% Cr-20 mass% Mo was used as the target (50) of the sputtering cathode in which the gas species used for the surface treatment by ion beam irradiation was changed to only argon gas (Ar). A double-sided metal laminate film was obtained in the same manner as in Example 1 except that the alloy used in Example 11 was a Ni-20 mass% Mo-7 mass% V alloy (Examples 10 and 11). Table 1 shows the determination results of (a) wrinkles and (b) peel strength.

(Examples 12 and 13)
By controlling the output of the cooling roll, the temperature rise of the insulating film before the first surface treatment step and after the second surface treatment step is 50 ° C. in Example 12 and 60 ° C. in Example 13. A double-sided metal laminate film was obtained in the same manner as in Example 1 except for adjusting to (Examples 12 and 13). As a result of visual judgment of wrinkles, almost no wrinkles were found in Example 12. On the other hand, in Example 13, fine wrinkles were found although they did not affect the performance of the double-sided metal laminated film. In the measurement of peel strength, both examples showed good values. Table 1 shows the determination results of (a) wrinkles and (b) peel strength.

(Comparative Example 1)
A double-sided metal laminate film was obtained in the same manner as in Example 1 except that the first and second surface treatments were not performed. Table 1 shows the measurement results of (a) determination of wrinkles and (b) peel strength at this time.

(Comparative Examples 2 to 4)
Surface treatment is performed on one surface (1a) of the polyimide film (1) to form a base metal layer (2a) and a copper thin film layer (3a), and then surface treatment is performed on the other surface (1b). The double-sided metal lamination was carried out in the same manner as in Example 1, except that the base metal layer (2b) and the copper thin film layer (3b) were formed, and the gas type used for the surface treatment by ion beam irradiation was changed. A film was obtained (Comparative Examples 2 to 4). Table 1 shows the measurement results of (a) determination of wrinkles and (b) peel strength at this time.

2. Manufacturing method of flexible double-sided printed wiring board Using the double-sided metal laminated film obtained by Examples 1-13 and Comparative Example 1, the flexible double-sided printed wiring board was manufactured. In addition, about the double-sided metal laminated film obtained from Comparative Examples 2-4, since wrinkles generate | occur | produced, the manufacture of a flexible double-sided printed wiring board was not performed. Specifically, a photosensitive resist (manufactured by Tokyo Ohka Kogyo Co., Ltd., PMERP-RH30PM) is applied to the surfaces of the copper plating layers on both sides of each double-sided metal laminated film, and comb-like wiring with a wiring width of 20 μm and a wiring spacing of 20 μm Exposed to form a pattern. Thereafter, the film was developed with an aqueous sodium carbonate solution having a concentration of 0.3% by mass, immersed in a ferric chloride solution (specific gravity 40 ° Baume, temperature 43 ° C.) for 2 minutes, washed with water, and dried. Thereafter, the resist was peeled off using an aqueous sodium hydroxide solution having a concentration of 4% by mass to obtain a flexible double-sided printed wiring board in which a comb-like wiring pattern having a wiring width of 20 μm and a wiring interval of 20 μm was formed on both surfaces.

  When the flexible double-sided printed wiring board obtained using the double-sided metal laminated film obtained in Examples 1 to 13 was observed with a microscope, no abnormality was found in these wirings. On the other hand, in the flexible double-sided printed wiring board obtained using the double-sided metal laminated film obtained in Comparative Example 1, a part of the wiring was peeled off.

DESCRIPTION OF SYMBOLS 1 Insulating film 1a, 1b Surface 2a, 2b Underlying metal layer 3a, 3b Copper thin film layer 4 Continuous sputtering apparatus 5 Vacuum chamber 6 Unwinding roll 7 Winding roll 8 Heater 9a 1st ion gun 9b 2nd ion gun 10-18 Guide roll 20 -22 Tension sensor roll 30, 31 Feed roll 40, 41 Cooling can roll 50, 51 Sputtering cathode 60, 61 Sputtering cathode 70 First dry film forming apparatus 71 Second dry film forming apparatus

Claims (12)

A method for producing a double-sided metal laminate film in which a copper coating layer is formed on the surface of the base metal layer after forming the base metal layer by dry plating without using an adhesive on both sides of the insulating film,
A first surface treatment step of irradiating one surface of the insulating film with an ion beam;
A second surface treatment step of irradiating the other surface of the insulating film with an ion beam after the first surface treatment step;
After the second surface treatment step, on the surface of any of the surface-treated insulating films, by a dry plating method, the base metal layer and a copper thin film layer constituting part or all of the copper coating layer A first dry film forming step of sequentially forming a film;
After the first dry film forming step, copper constituting a part or all of the base metal layer and the copper coating layer is formed by dry plating on the surface of the insulating film on which the copper thin film layer is not formed. A second dry film forming step of sequentially forming a thin film layer;
A method for producing a double-sided metal laminate film.   The method for producing a double-sided metal laminated film according to claim 1, wherein the insulating film has a thickness of 20 μm or less.   The ion beam irradiation in the first surface treatment step and the second surface treatment step uses argon, nitrogen, oxygen, or at least two mixed gases selected from these groups. Or the manufacturing method of the double-sided metal laminated film of 2.   The double-sided metal according to claim 3, wherein the first surface treatment step and the second surface treatment step are performed by a roll-to-roll film processing apparatus provided with an ion gun that can irradiate the insulating film from one direction. A method for producing a laminated film.   The manufacturing method of the double-sided metal laminated film in any one of Claims 1-4 whose temperature rise of the insulating film before a 1st surface treatment process and a 2nd surface treatment process is 50 degrees C or less.   The manufacturing method of the double-sided metal laminated film in any one of Claims 1-5 whose said dry-type plating method is sputtering method.   The insulating film is selected from a polyimide film, a polyamide film, a polyester film, a polytetrafluoroethylene film, a polyfinylene sulfide film, a polyethylene naphthalate film, and a liquid crystal polymer film. 6. A method for producing a double-sided metal laminated film according to any one of 6 above.   The manufacturing method of the double-sided metal laminated film in any one of Claims 1-7 using the nickel-chromium alloy which contains chromium in the range of 15 mass%-25 mass% as said base metal layer.   The manufacturing method of the double-sided metal laminated film in any one of Claims 1-8 which makes the film thickness of the said copper coating layer into the range of 0.01 micrometer-35 micrometers.   The method further comprises a wet film forming step of forming a copper plating layer for forming a copper coating layer together with the copper thin film layer on both side surfaces of the copper thin film layer by a wet plating method after the second dry film forming step. The manufacturing method of the double-sided metal laminated film in any one of claim | item 1 -9. An apparatus for producing a double-sided metal laminated film according to the production method of claim 1,
A vacuum chamber, and a roll-to-roll film processing apparatus disposed in the vacuum chamber,
The roll-to-roll film processing apparatus includes an unwinding roll, a winding roll, and a film track between these rolls,
A first ion gun that irradiates one surface of the insulating film with an ion beam;
A second ion gun disposed downstream of the first ion gun on the opposite side of the first ion gun across the film trajectory and irradiating the other surface of the insulating film with an ion beam;
The base metal layer and a copper thin film layer constituting a part or all of the copper coating layer are sequentially formed on any surface of the insulating film disposed on the downstream side of the second ion gun and subjected to a surface treatment. A first dry film forming apparatus for forming a film;
On the downstream side of the first dry film forming apparatus, disposed on the opposite side of the first dry film forming apparatus across the film trajectory, and on the surface of the insulating film on which the copper thin film layer is not formed, A second dry film forming apparatus for sequentially forming a base metal layer and a copper thin film layer constituting part or all of the copper coating layer;
Comprising
Manufacturing equipment for double-sided metal laminate film.   The manufacturing method of a flexible double-sided printed wiring board which carries out wiring processing of the double-sided metal laminated film manufactured by the manufacturing method in any one of Claims 1-10 by a subtractive method or a semiadditive method.