JP6677448B2 - Copper clad laminate and method for producing copper clad laminate - Google Patents

Description

  The present invention relates to a copper-clad laminate and a method for producing the copper-clad laminate.

  Conventionally, copper-clad laminates have been used as substrates for producing flexible wiring boards. Further, the manufactured flexible wiring boards are widely used as wiring members in electronic devices such as liquid crystal panels and mobile phones.

  A copper-clad laminate has a three-layer substrate in which a resin film and a metal conductor layer such as a copper layer are bonded together via an adhesive, and an adhesive layer between the resin film and the metal conductor layer. It can be broadly divided into two-layer substrates.

  The three-layer substrate uses a copper foil as a metal conductor layer, and can be manufactured by bonding to a resin film via an adhesive.

  On the other hand, the following three types of manufacturing methods are generally known as a method for manufacturing a two-layer substrate. They are: (1) A casting method in which a polyimide varnish is applied to a copper foil to be a metal conductor layer and a polyimide film layer is formed by heating. (2) A lamination method in which a thermoplastic polyimide-based adhesive is applied to a polyimide film and heated and pressed against a copper foil to be a metal conductor layer. (3) After laminating a metal layer such as a copper layer directly on the polyimide film surface by a sputtering method or a vapor deposition method, if necessary, thicken the copper layer using an electroplating method or an electroless plating method to form a metal conductive layer. Metallization method for forming body layers. These manufacturing methods are properly used according to the specifications such as the wiring pitch and the electronic device used.

  Conventionally, the surface of the copper layer is treated with a rust inhibitor in order to suppress rusting of the copper layer of the copper-clad laminate manufactured as described above. For example, Patent Literatures 1 to 3 disclose that a rust-proofing treatment is performed on a copper foil of a copper-clad laminate prepared by bonding a polyimide film and a copper foil or by heating and pressing. .

  In addition, a flexible wiring board is manufactured by subjecting a copper-clad laminate to wiring processing. The methods are roughly classified into a subtractive method and a semi-additive method.

  In the subtractive method, a copper-clad laminate having a relatively thick copper layer is used as a substrate, and a photoresist is applied to the surface of the substrate, exposed and developed to form a desired pattern. Using the formed photoresist pattern as a mask, the exposed copper layer is removed by etching, and the photoresist is peeled off to form a wiring pattern.

  On the other hand, in the semi-additive method, a copper-clad laminate having a relatively thin copper layer is used as a substrate, and the same steps are performed up to the formation of a photoresist pattern in the subtractive method. Thereafter, using the photoresist pattern as a mask, a copper layer is further laminated on the exposed copper layer by electroplating, and the photoresist is peeled off. Next, a method of forming a wiring pattern by removing the copper layer or the like on the substrate in a portion masked with a photoresist (a portion where the copper layer is not laminated by the electroplating process) on the substrate by flash etching.

JP 2005-322682 A JP 2009-196098 A JP 2007-152835 A

  As described above, the copper-clad laminate is processed into a flexible wiring board by a subtractive method or a semi-additive method, and in each case, photoresist coating, exposure, and development are performed.

  However, when a copper-clad laminate subjected to rust-prevention treatment is used, the photoresist pattern may be peeled off from the copper-clad laminate, which is a substrate, to cause a problem that wiring processing cannot be performed.

  In view of the above problems of the prior art, an aspect of the present invention is to provide a copper-clad laminate that has been subjected to a rust-preventive treatment and that can prevent a photoresist pattern from peeling even when a photoresist pattern is arranged. Aim.

In one embodiment of the present invention to solve the above problems,
A resin film,
A copper layer formed on at least one side of the resin film and having a first surface facing the resin film and a second surface opposite to the first surface; ,
A rust-proof treatment is applied to the second surface of the copper layer, and a copper-clad laminate in which the contact angle of the rust-proof treated second surface to pure water is 45 ° or more and 80 ° or less. provide.

  According to one embodiment of the present invention, it is possible to provide a copper-clad laminate that has been subjected to rust-preventive treatment and can prevent the photoresist pattern from peeling off even when a photoresist pattern is arranged.

1 is a cross-sectional configuration example of a copper-clad laminate according to an embodiment of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS The schematic side view of the electroplating / rust prevention processing apparatus which can be used in the manufacturing process of the copper clad laminated board which concerns on embodiment of this invention. FIG. 4 is a photographic view of a mask used in a photoresist pattern peeling test in Examples and Comparative Examples. FIG. 9 is a photographic view showing a state during a peeling test of a photoresist pattern in Comparative Example 1.

Hereinafter, one example of the configuration of the copper-clad laminate and the method for producing the copper-clad laminate of the present invention will be described.
[Copper clad laminate]
The copper-clad laminate of the present embodiment is a resin film, a first surface formed on at least one surface of the resin film, and a first surface facing the resin film, and a first surface opposite to the first surface. And a copper layer having a second surface. The second surface of the copper layer is subjected to rust prevention treatment, and the contact angle of the second surface subjected to rust prevention treatment with pure water can be set to 45 ° or more and 80 ° or less.

  FIG. 1 shows an example of a cross-sectional configuration of the copper-clad laminate of the present embodiment.

  FIG. 1 is a diagram schematically showing a cross-sectional configuration of a copper-clad laminate of the present embodiment in a plane parallel to a laminating direction of a resin film and a copper layer.

  As shown in FIG. 1, the copper clad laminate 10 of the present embodiment can have a resin film 11 and a copper layer 12.

  And the copper layer 12 can have the 1st surface 12a facing the resin film 11, and the 2nd surface 12b opposite to the 1st surface 12a. Since the second surface 12b of the copper layer 12 is exposed, there is a possibility that rust may occur due to a change over time. For this reason, rust prevention treatment can be performed on the second surface 12b as described above.

  Although the copper-clad laminate 10 shown in FIG. 1 shows an example in which the resin film 11 and the copper layer 12 are directly laminated, the present invention is not limited to such a form. An adhesive layer may be provided between the film 11 and the copper layer 12 to form a three-layer substrate. Further, a metal seed layer or the like can be provided between the resin film 11 and the copper layer 12.

  In the copper-clad laminate 10 shown in FIG. 1, an example is shown in which the copper layer 12 is provided only on the upper surface side of the resin film 11, but the present invention is not limited to such a form, and the copper layer or the like is also provided on the lower surface side. Can also be arranged.

  By the way, in order to carry out wiring processing on the copper layer 12 and obtain a flexible wiring board having a desired wiring pattern, in either case of the subtractive method or the semi-additive method, the flexible wiring board is formed on the second surface 12b of the copper layer 12. A photoresist will be placed. However, since the second surface 12b of the copper layer 12 has been subjected to the rust preventive treatment as described above, a rust preventive agent layer is formed. For this reason, there has been a problem that the photoresist is easily peeled off.

  Then, the inventors of the present invention studied a method for suppressing the peeling of the photoresist, and found that the contact angle of the rust-proofed second surface to pure water was 45 ° or more and 80 ° or less. The present inventors have found that the removal of the photoresist can be suppressed, and completed the present invention.

  Hereinafter, the members of the copper-clad laminate of the present embodiment will be described in detail.

  The resin film 11 will be described.

  The material of the resin film 11 is not particularly limited, and any material can be used. Examples of the resin film 11 include a polyimide film, a polyamide film, a polyester film such as polyethylene terephthalate (PET) and polyethylene terephthalate (PEN), a polytetrafluoroethylene film, a polyphenylene sulfide film, and a polyethylene naphthalate film. Or a liquid crystal polymer film. In particular, the material can be appropriately selected from these materials in consideration of heat resistance, dielectric properties, electrical insulation, chemical resistance in a manufacturing process of a flexible wiring board and a subsequent process, a use, and the like. As the resin film 11, a polyimide-based film can be preferably used, and a polyimide film can be more preferably used.

  The thickness of the resin film 11 can be arbitrarily selected according to the use and the like, and is not particularly limited. For example, the thickness is preferably 10 μm or more and 50 μm or less.

  Next, the copper layer 12 will be described.

  Although the configuration of the copper layer 12 is not particularly limited, the copper layer 12 can be composed of, for example, a copper thin film layer formed by a dry plating method. Further, the copper layer 12 may be composed of, for example, a copper thin film layer formed by a dry plating method and a copper plating layer formed by a wet plating method.

  The thickness of the copper layer 12 is not particularly limited, and can be arbitrarily selected according to, for example, the magnitude of the current supplied to the manufactured flexible wiring board, but is, for example, 0.1 μm or more and 20 μm or less. Is preferred.

  Note that the thickness of the copper layer is preferably selected by a method for wiring a flexible wiring board using such a copper-clad laminate. Specifically, for example, when wiring a copper-clad laminate by a subtractive method, the thickness of the copper layer is more preferably 5 μm or more and 12 μm or less. Further, when wiring the copper-clad laminate by the semi-additive method, the thickness of the copper layer is more preferably 0.1 μm or more and 4 μm or less.

  Then, the second surface 12b of the copper layer 12 can be subjected to a rust prevention treatment.

  The rust preventive treatment can be performed, for example, by supplying a rust preventive agent to the second surface 12b of the copper layer 12 by coating or the like. Note that a rust preventive layer can be formed on the second surface 12b of the copper layer 12 by applying a rust preventive or the like.

  The rust preventive used at this time is not particularly limited, but it is preferable to use an organic rust preventive. This is because when an organic rust inhibitor is used, it is bonded and adsorbed to copper to form a strong rust inhibitor layer, and when the second surface 12b of the copper layer 12 is subjected to rust prevention treatment, the second surface 12b Is particularly easy to adjust the contact angle.

  Among the organic rust inhibitors, azoles can be more preferably used. In addition, a plurality of rust preventive components including azoles may be mixed and used.

  Specific examples of the azoles include benzothiazole, benzotriazole, imidazole and the like, and benzotriazole can be more preferably used.

  The rust preventive is applied to the copper-clad laminate 10 in the form of an aqueous solution, for example, or the copper-clad laminate 10 is immersed in an aqueous solution of a rust preventive to rust-proof the second surface 12b of the copper layer 12. It can be treated and can exhibit a rust prevention effect. When an organic rust preventive is used as the rust preventive, the organic rust preventive has a low solubility in water. Therefore, it is preferable to use an aqueous solution to which alcohol is added. As the alcohol to be added, those containing methyl alcohol or ethyl alcohol as a main component are preferable.

  Here, according to the study of the inventors of the present invention, by setting the contact angle of the second surface 12b of the copper layer 12 to pure water within a predetermined range, the second surface 12b of the copper layer 12 When the photoresist is arranged, it is possible to prevent the photoresist from peeling off. According to the study by the inventors of the present invention, when the second surface 12b of the copper layer 12 is subjected to the rust prevention treatment, the concentration of the rust inhibitor to be supplied to the second surface 12b is selected. It is possible to select a contact angle of the second surface 12b with pure water.

  For example, when a copper layer is rust-proofed using an organic rust inhibitor, as the amount (concentration) of the organic rust inhibitor used increases, the thickness of the rust inhibitor layer covering the copper layer tends to increase. . Since the organic rust preventive exhibits hydrophobicity as can be seen from the low solubility of water, the contact angle with pure water increases as the thickness of the rust preventive layer increases. Conversely, if the contact angle of the copper layer subjected to the rust-preventive treatment to pure water decreases, it indicates that the thickness of the rust-preventive agent layer is small or almost nonexistent.

  According to the study by the inventors of the present invention, the contact angle of the second surface 12b of the copper layer 12 subjected to the rust prevention treatment with pure water is preferably 45 ° or more and 80 ° or less, and 45 ° or less. It is more preferable that it is not less than 70 ° and not more than 70 °.

  This is because when the contact angle of the second surface 12b of the copper layer 12 subjected to the rust-proof treatment with pure water is 45 ° or more, a sufficient rust-proof effect is exhibited.

  However, the rust-preventive agent layer formed on the second surface 12b of the copper layer 12 is coated with a photoresist in a step of manufacturing a flexible wiring board using the copper-clad laminate as a substrate, for example. This is a factor that lowers the adhesion between the resist pattern and the copper layer. For this reason, when the film thickness of the rust preventive agent layer is too thick, a phenomenon that the photoresist pattern is peeled off may occur. According to the study of the inventors of the present invention, the contact angle of pure copper on the second surface 12b of the rust-proofed copper layer 12 with pure water is set to 80 ° or less as described above, so that the pattern of the photoresist is reduced. Is preferred because it can suppress peeling from the copper layer 12.

  The contact angle of the second surface 12b of the copper layer 12 with the pure water can be measured at two or more arbitrarily selected plural points of the second surface 12b of the copper layer 12 subjected to the rustproofing treatment. Preferably, when measured at a plurality of points, the minimum value and the maximum value are preferably within the above-mentioned range.

  The amount of the rust preventive agent attached to the copper layer 12 also increases or decreases according to the amount (concentration) of the rust preventive agent. Have difficulty. For this reason, in the past, the non-uniformity of the rust preventive agent layer was reduced until the copper layer partially rusted or the pattern of the photoresist applied, exposed and developed on the copper layer partially peeled off. I couldn't judge. On the other hand, the contact angle with respect to pure water can be seen even in a relatively narrow area. For this reason, even the non-uniformity of the rust preventive agent layer can be detected, and it is effective to determine the effect of the rust preventive treatment based on the amount of adhesion.

  Then, as described above, by making the contact angle of the second surface 12b of the copper layer 12 with pure water 45 ° or more and 80 ° or less, the layer of the rust inhibitor is uniformly formed on the second surface of the copper layer 12. It can be in a formed state. Therefore, from the viewpoint of more reliably preventing rusting of the copper layer 12, the contact angle of the second surface 12b of the copper layer 12 with pure water preferably satisfies 45 ° or more and 80 ° or less.

  The copper layer 12 can be subjected to the rust prevention treatment not only on the second surface 12b but also on a side surface portion, for example, the side surface 12c.

  In particular, it is preferable that the copper layer 12 be subjected to a rust prevention treatment on an exposed surface that is not covered with the resin film 11 or the like. When performing the rust-prevention treatment on the second surface 12b of the copper layer 12, the rust-prevention treatment can also be performed on the side surface 12c and the like. Therefore, the side surface 12c and the like can have the same contact angle with respect to pure water as the second surface 12b.

  The copper-clad laminate of the present embodiment may include other layers in addition to the resin film 11 and the copper layer 12 described above.

  As described above, a three-layer board and a two-layer board are known as copper-clad laminates. In the case of a three-layer substrate, an adhesive layer can be provided between the resin film and the copper layer. Various methods such as a casting method, a laminating method, and a metallizing method are known as a method for manufacturing a copper-clad laminate of a two-layer substrate. Necessary layers and optional layers can be further provided according to each manufacturing method. For example, when manufacturing a copper-clad laminate by a metallization method, a metal seed layer may be provided between the resin film 11 and the copper layer 12.

  The metal seed layer contributes to improving the adhesion between the resin film and the copper layer and the insulation reliability of the flexible wiring board. As such a metal seed layer, it is preferable to use nickel or a nickel alloy obtained by adding one or more elements selected from chromium, vanadium, titanium, molybdenum, cobalt, and tungsten to nickel. Among these, a nickel-chromium alloy is preferable, and a nickel-chromium alloy having a chromium content of 15% by mass or more and 25% by mass or less is more preferable. Such a nickel-chromium alloy has high insulation reliability and can be easily processed for wiring.

  The thickness of the metal seed layer is appropriately determined according to the type and composition of the metal or alloy forming the metal seed layer, ease of wiring processing on a flexible wiring board, adhesion required for wiring, insulation reliability, and the like. The selection is not particularly limited. The thickness of the metal seed layer is preferably, for example, not less than 3 nm and not more than 50 nm. When the thickness of the metal seed layer is less than 3 nm, when the copper layer other than the wiring portion is removed by etching or the like and wiring processing is performed, the etchant easily permeates between the resin film and the copper layer, and the wiring rises. This is because there is a possibility that a problem may occur. On the other hand, if the film thickness of the metal seed layer exceeds 50 nm, the metal seed layer may remain without being completely removed when finally forming a wiring pattern by etching, which may cause insulation failure between wirings. That's why.

Although the copper-clad laminate of the present embodiment has been described above, since the second surface 12b of the copper layer 12 is subjected to the rust prevention treatment, it is possible to prevent rust from being generated in the copper layer. Further, since the contact angle of the second surface 12b of the copper layer 12 with the pure water is within a predetermined range, a photoresist pattern is arranged on the second surface 12b of the copper layer 12 to process the flexible wiring board. However, peeling of the photoresist pattern can be suppressed.
[Production method of copper-clad laminate]
Next, a method for manufacturing the copper-clad laminate of the present embodiment will be described.

  The method for manufacturing a copper-clad laminate according to the present embodiment includes a resin film, a first surface formed on at least one surface of the resin film, facing the resin film, and a surface opposite to the first surface. And a copper layer having a copper layer having a second surface. Then, in the rust prevention treatment step, the rust prevention treatment can be performed such that the contact angle of the second surface with pure water is 45 ° or more and 80 ° or less.

  The above-described copper-clad laminate can be suitably produced by the method for producing a copper-clad laminate according to the present embodiment. For this reason, a part of the matters already described in the copper clad laminate will not be described.

  As described above, the method for manufacturing a copper-clad laminate according to the present embodiment involves preventing the second surface 12b of the copper layer 12 from being subjected to a rust-proof treatment for the copper-clad laminate 10 in which the copper layer 12 is formed on the resin film 11. It can have a rust treatment step. The rustproofing process can be performed by supplying a rustproofing agent to the second surface 12b of the copper layer 12.

  In the rustproofing process, the method of supplying the rustproofing agent to the second surface 12b of the copper layer 12 is not particularly limited, and the rustproofing process can be performed by any method. For example, a method of applying a rust inhibitor to an aqueous solution and applying it to the copper-clad laminate 10 or immersing the copper-clad laminate 10 in an aqueous solution of a rust inhibitor to immerse the copper-clad laminate in a solution of the rust inhibitor By this method, a rust inhibitor can be supplied to the second surface 12b of the copper layer 12.

  The rust preventive used in the rust preventive treatment step is not particularly limited. For example, it is preferable to use an organic rust preventive. This is because when an organic rust inhibitor is used, it is bonded and adsorbed to copper to form a strong rust inhibitor layer, and when the second surface 12b of the copper layer 12 is subjected to rust prevention treatment, the second surface 12b Is particularly easy to adjust the contact angle.

  Among the organic rust inhibitors, azoles can be more preferably used. In addition, a plurality of rust preventive components including azoles may be mixed and used.

  Specific examples of the azoles include benzothiazole, benzotriazole, imidazole and the like, and benzotriazole can be more preferably used.

  When an organic rust preventive is used as the rust preventive, the organic rust preventive has a low solubility in water. Therefore, it is preferable to use an aqueous solution to which alcohol is added. That is, the organic rust inhibitor preferably contains an alcohol. As the alcohol to be added, those containing methyl alcohol or ethyl alcohol as a main component are preferable.

  Here, according to the study of the inventors of the present invention, by setting the contact angle of the second surface 12b of the copper layer 12 to pure water within a predetermined range, the second surface 12b of the copper layer 12 When the photoresist is arranged, it is possible to prevent the photoresist from peeling off.

  According to the study of the inventors of the present invention, the contact angle of the second surface 12b of the copper layer 12 with pure water is the second contact angle when the second surface 12b of the copper layer 12 is subjected to rust prevention treatment. It can be selected by selecting the concentration or the like of the rust inhibitor supplied to the surface 12b.

  For example, when a copper layer is rust-proofed using an organic rust inhibitor, as the amount (concentration) of the organic rust inhibitor used increases, the thickness of the rust inhibitor layer covering the copper layer tends to increase. . Since the organic rust preventive exhibits hydrophobicity as can be seen from the low solubility of water, the contact angle with pure water increases as the thickness of the rust preventive layer increases.

  Then, in order to suppress the occurrence of peeling when the photoresist is disposed, the contact angle of the second surface 12b of the copper layer 12 after the rust prevention treatment with pure water is preferably 45 ° or more and 80 ° or less. , 45 ° or more and 70 ° or less.

  This is because according to the study of the inventors of the present invention, when the contact angle of the second surface 12b of the copper layer 12 with pure water is 45 ° or more, a sufficient rust-preventing effect is exhibited.

  However, the rust preventive layer formed on the second surface 12b of the copper layer 12 is coated with a photoresist in a step of manufacturing a flexible wiring board using the copper-clad laminate as a substrate, exposed to light, and developed. This is a factor that lowers the adhesion between the pattern and the copper layer. For this reason, if the thickness of the rust preventive agent layer is too thick, a phenomenon occurs in which the photoresist pattern is peeled off after developing the photoresist, for example, while performing various processes using the photoresist. Sometimes. According to the study of the inventors of the present invention, when the contact angle of pure copper on the second surface 12b of the rust-proofed copper layer 12 with respect to pure water is 80 ° or less, the pattern of the photoresist may be separated from the copper layer. This is preferable because it can suppress

  In addition, the contact angle of the second surface 12b of the copper layer 12 with the pure water may be determined by performing a rust-prevention treatment process, and then selecting two or more arbitrarily selected points on the second surface 12b of the copper layer 12. It is preferable to measure with. When measured at a plurality of points, it is preferable that the minimum value and the maximum value fall within the above-mentioned ranges.

  Then, as described above, by making the contact angle of the second surface 12b of the copper layer 12 with pure water 45 ° or more and 80 ° or less, the layer of the rust inhibitor is uniformly formed on the second surface of the copper layer 12. It can be in a formed state. Therefore, from the viewpoint of more reliably preventing rusting of the copper layer 12, the contact angle of the second surface 12b of the copper layer 12 with pure water preferably satisfies 45 ° or more and 80 ° or less.

  In the rust prevention process, not only the second surface 12b of the copper layer 12 but also a side surface portion, for example, the side surface 12c can be subjected to the rust prevention process in the same manner.

  In particular, it is preferable that the copper layer 12 be subjected to a rust prevention treatment on an exposed surface that is not covered with the resin film 11 or the like. When performing the rust-prevention treatment on the second surface 12b of the copper layer 12, the rust-prevention treatment can also be performed on the side surface 12c and the like. Therefore, the side surface 12c and the like can have the same contact angle with respect to pure water as the second surface 12b.

  In the rust preventive treatment step, after supplying the rust preventive agent to the second surface 12b of the copper layer 12, it is also possible to wash with water as needed to remove the excessive rust preventive agent. In addition, when washing with water is performed, it is preferable to carry out draining and drying together.

  In addition, the method for manufacturing a copper-clad laminate according to the present embodiment can include an arbitrary step other than the above-described rust prevention treatment step.

  Specifically, for example, a step of manufacturing a copper-clad laminate before subjecting to the above-described rust prevention step in which a copper layer 12 is disposed on a resin film 11 can be provided. When manufacturing a copper-clad laminate by a metallization method, the following steps can be included.

  Forming a metal seed layer on at least one surface of the resin film by a dry plating method;

  Forming a copper thin film layer on the metal seed layer by dry plating;

  A copper plating layer forming step of forming a copper plating layer by an electroplating method and / or an electroless plating method.

  Hereinafter, each step will be specifically described.

  First, the metal seed layer forming step will be described.

  As described above, the metal seed layer contributes to improving the adhesion between the resin film 11 and the copper layer 12 and the insulation reliability of the flexible wiring board.

  Since a material that can be suitably used as a material for the metal seed layer and a preferable film thickness of the metal seed layer have already been described, the description is omitted here.

  The metal seed layer can be formed, for example, on a resin film by a dry plating method. Examples of the dry plating method include an evaporation method, a sputtering method, an ion plating method, and the like. However, it is preferable to form the film by a sputtering method because the thickness can be easily controlled.

  Note that, without providing a metal seed layer, a copper thin film layer or a copper plating layer may be further formed directly on the resin film in some cases. In this case, the metal seed layer forming step can be omitted.

  Next, a copper thin film layer forming step will be described. Note that a copper layer can be formed by the copper thin film layer formed in this step and a copper plating layer described later. Further, depending on the thickness of the copper layer, the copper layer can be formed from the copper thin film layer formed in this step.

  The thickness of the copper thin film layer formed by the dry plating method is preferably 0.01 μm or more and 1 μm or less, more preferably 0.1 μm or more and 0.5 μm or less.

  When the thickness of the copper thin film layer is less than 0.01 μm, when a copper plating layer to be described later is formed (thickened) by electroplating or when electroplating for wiring processing by a semi-additive method, Insufficient power supply may result in non-uniform stacking of copper layers, or lower productivity. On the other hand, since the film forming rate by the dry plating method is slower than the film forming rate by the electroplating method or the electroless plating method described later, the productivity is reduced when trying to form a film exceeding 1 μm by the dry plating method. Therefore, as described above, the thickness of the copper thin film layer is preferably 0.01 μm or more and 1 μm or less.

  Next, the copper plating layer forming step will be described.

  As described above, when the thickness of the copper layer to be formed is large, there is a problem that productivity is reduced when the copper layer is formed only by the dry plating method. For this reason, when a copper layer is thickened, for example, when the thickness of the copper layer is set to 1 μm or more, a copper thin film layer which is a part of the copper layer is formed by dry plating, and then electroplating or non-plating. The copper plating layer is preferably formed by an electrolytic plating method or a method combining these two methods.

  The conditions for forming the copper plating layer in the copper plating layer forming step are not particularly limited, and the copper plating layer can be formed by an ordinary method using an electroplating method and / or an electroless plating method.

  When the thickness of the copper layer is less than 1 μm, the copper layer can be formed only by the copper thin film layer forming step without performing the copper plating layer forming step. In this case, the copper layer is constituted only by the copper thin film layer.

  Although the final thickness of the copper layer is not particularly limited, it is preferably, for example, 0.1 μm or more and 20 μm or less. In addition, the final thickness of the copper layer is determined in some ways by the wiring processing method of the flexible wiring board, and is preferably 5 μm or more and 12 μm or less when wiring is processed by the subtractive method. Further, when wiring is processed by the semi-additive method, the thickness is preferably 0.1 μm or more and 4 μm or less.

  Here, the final thickness of the copper layer means the thickness of the copper thin film layer when the copper layer is composed of only the copper thin film layer. Further, when the copper layer is composed of a copper thin film layer and a copper plating layer, it means the total thickness of the copper thin film layer and the copper plating layer.

  After performing the copper plating layer forming step described so far, the above-described rustproofing step is performed, whereby a copper-clad laminate subjected to rustproofing processing can be manufactured.

  Next, an example of a configuration of an apparatus in a case where a copper plating layer is formed by an electroplating method in a copper plating layer forming step and a rust prevention treatment step is continuously performed will be described with reference to FIG.

  FIG. 2 shows a schematic side view of an electroplating / rust prevention treatment apparatus.

  2 is a resin film (hereinafter referred to as a metallized resin film F) in which a metal conductor layer including a copper thin film layer is formed on at least one side by a dry plating method in a preceding stage (not shown). Is carried out, and electroplating is carried out while being transported by a roll-to-roll method. Then, a copper-clad laminate S having a thickened copper layer is produced.

Specifically, an unwinding roll 21 from which the metallized resin film F wound in a roll is unwound, an electroplating unit 22 for thickening a copper layer on the metallized resin film F conveyed by rollers, and And a plating solution removing unit 23 for removing the plating solution attached in the electroplating unit 22. After the plating solution removing unit 23, the coating of rust inhibitor on the copper-clad laminate S having a copper layer which is thickened by electroplating unit 22, a post-processing unit 24 for performing drying, etc., rust treatment And the like, and a take-up roll 25 for winding the copper-clad laminate S having been subjected to the above-described steps into a roll.

  Each part will be described. In the electroplating / rust preventing apparatus 20 shown in FIG. 2, the electroplating unit 22 includes four parallel anodes 221 (anodes) in a plating tank into which a plating solution (not shown) is inserted. It is provided to be immersed. Also, five rollers 222 are alternately arranged below the liquid surface and above the liquid surface so that the metallized resin film F can continuously face the anode 221. Then, power is supplied to the anode 221 and the roller 222 on the liquid level by a power supply device (not shown). The inside of the plating tank is divided into two tanks each having two anodes 221 and one roller 222 by a partition plate (not shown). Note that the number of anodes 221 and rollers 222 may be increased or decreased as necessary, such as a desired thickness of the copper layer. A known plating solution may be used. For example, a plating solution containing an additive such as a chloride ion or a brightener in an aqueous solution of copper sulfate can be used.

  The plating solution removing unit 23 includes two pairs of rollers 231 for vertically sandwiching and transporting the copper-clad laminate S in which the copper layer is attached to the metallized resin film F from above and below, and the washing water positioned therebetween. And a spraying device 232. When the copper-clad laminate S passes through the plating solution removing section 23, the plating solution attached to the copper-clad laminate S can be washed and removed.

  The post-processing part 24 is a part for forming a coating of a rust inhibitor on the surface of the copper-clad laminate S on which the copper layer is thickened, and is processed in the order of application of a rust inhibitor, washing with water, draining, and drying. The copper-clad laminate S is wound up in a roll shape by the wind-up roll 25.

  For example, as shown in FIG. 2, the rust preventive agent is applied by a spray nozzle method, a shower ring method, a blow-up method in which the rust preventive agent is sprayed from below the copper-clad laminate S by a rust preventive spraying device 241. Known methods such as a mist method and an electrodeposition method can be used. Alternatively, the entire copper-clad laminate S may be immersed in an aqueous solution of a rust inhibitor stuck in a container.

  After the application of the rust preventive, the copper-clad laminate S can be washed with water by the washing means 242, the water used in the water washing can be drained by the draining means 243, and the copper-clad laminate S can be dried by the drying means 244.

  Washing with water after the application of the rust inhibitor can be carried out for the purpose of preventing an excessive rust inhibitor that does not adhere or adsorb to the copper layer from remaining on the surface of the copper layer. In addition, when the copper-clad laminate S is wound up in a roll shape by the winding roll 25 with insufficient removal of water during draining and drying, the rust inhibitor re-aggregates during the drying process and partially concentrates. Can be implemented for the purpose of suppressing this.

  The washing means 242, draining means 243, and drying means 244 described above are not particularly limited, and can be implemented by any means. For example, drying may be performed using a known method, but heating air is supplied from a gas supply port to a box in which a slit through which a copper-clad laminate enters and exits and a gas supply port and a discharge port are arranged, and drying is performed. Or drying using an oven.

  Since the rust preventive agent that can be suitably used in the post-processing unit 24 has been described above, the description is omitted here.

  Further, the concentration of the rust preventive used in the post-processing unit 24 and the conditions such as washing, draining, and drying are not particularly limited, and the contact angle of the rust-proofed copper layer with respect to pure water is within a predetermined range. What is necessary is just to set suitably so that it may become inside.

  Here, using a metallization method, a metal seed layer is formed on at least one side of the resin film and a copper layer is formed on the surface by dry plating, and the copper layer is further formed on the surface by electroplating. What was applied to the rust-proof treatment for the finished copper-clad laminate was shown. However, as described above, the present invention is not limited to the above method and the copper-clad laminate obtained by the above method.

  As described above, as a copper-clad laminate, a three-layer board, a copper-clad laminate of a two-layer board produced by a casting method, a lamination method, and the like are also known. As described above, the rust-proofing step can be performed to form a copper-clad laminate.

  The three-layer board refers to a copper-clad laminate in which a resin film and a copper foil are bonded via an adhesive. In addition, the casting method is a method of forming a resin film layer by applying a varnish as a raw material of a resin film to a copper foil, and the laminating method is a method of applying a thermoplastic polyimide-based adhesive to a polyimide film to form a copper foil. It refers to the method of thermocompression bonding. Of course, when producing a copper-clad laminate using a copper foil, it goes without saying that the copper layer of the present embodiment means a copper foil.

  The copper-clad laminate and the method for manufacturing the copper-clad laminate according to the present embodiment have been described above. According to the copper-clad laminate and the method for manufacturing a copper-clad laminate of the present embodiment, the rust-preventive treatment is performed on the second surface of the copper layer so that the contact angle with pure water is in a desired range. For this reason, a copper layer wiring board in which rust is prevented from being generated in the copper layer can be obtained. Further, even when a photoresist pattern is arranged and processed into a flexible wiring board or the like, a copper-clad laminate can be provided that can prevent the photoresist pattern from peeling off.

  Hereinafter, the present invention will be described with reference to specific examples and comparative examples, but the present invention is not limited to these examples.

First, an evaluation method of the copper-clad laminates manufactured in the following examples and comparative examples will be described.
(Contact angle with pure water)
On the second surface of the copper layer of the copper-clad laminate, using an automatic contact angle meter DM-301 (manufactured by Kyowa Interface Science Co., Ltd.), the copper layer was deposited under the conditions of a dropping pure water amount of 1.0 μl and a temperature of 25 ° C. The angle formed between the surface and the water drop by pure water was measured at five points, and evaluated by the minimum value and the maximum value.
(Long-term storage test)
The prepared copper-clad laminate was stored at room temperature for 500 hours, and the presence or absence of rust on the surface of the copper layer was visually checked.
(Photoresist pattern peeling test)
A liquid photoresist was applied to the copper-clad laminate, and exposed to ultraviolet light through a mask having the pattern shown in FIG. Next, development was performed to form a photoresist pattern. During this development, the presence or absence of peeling of the photoresist pattern from the copper layer was checked.
[Example 1]
On a surface of a 38 μm-thick polyimide film (Kapton (registered trademark) manufactured by Du Pont-Toray Co., Ltd.), a nickel-20 mass% chromium alloy film having a film thickness of 10 nm was formed as a metal seed layer by a sputtering method ( Metal seed layer forming step).

  Next, a copper thin film layer having a thickness of 100 nm was further laminated on the surface of the metal seed layer by a sputtering method (copper thin film layer forming step). The metallized resin film F in which the copper thin film layer was formed on the resin film was wound into a roll.

  The produced metallized resin film F is unwound from an unwinding roll 21 using an electroplating and rust prevention treatment apparatus as shown in FIG. A plating layer was formed (copper plating layer forming step) to obtain a copper-clad laminate S having a thick copper layer.

Then, the plating solution attached to the copper-clad laminate S was removed by the plating solution removing section 23 . Further, an organic rust preventive was applied in the post-processing section 24 , washed with water, drained, and dried with heated air (rust prevention treatment step) , and then wound up by the take-up roll 25.

  In the electroplating section 22, a plating solution containing 100 g / L of sulfuric acid and 180 g / L of copper sulfate and having a chlorine content of 50 mass ppm is used, and additives are added thereto for the purpose of ensuring the smoothness of the copper plating film. did. The metallized resin film F was applied to the electroplated portion 22 at 3 m / min. , The thickness of the copper layer of the metallized resin film F was increased to 8 μm.

  As the aqueous solution of the organic rust inhibitor in the post-treatment section 24, an aqueous solution prepared by adding and adjusting benzotriazole to 0.4% by mass and methyl alcohol to 1.0% by mass was used.

  Pure water was used for the washing water sprayed from the washing water spraying device 232 in the plating solution removing unit 23 and the washing solution sprayed from the washing means 242 when washing in the post-processing unit 24.

  When the contact angle of the copper layer of the obtained copper-clad laminate to pure water was measured, the minimum value was 59 ° and the maximum value was 61 °.

Further, a long-term storage test of the copper-clad laminate was performed, and it was confirmed that the copper-clad laminate did not rust. Further, a peeling test of the photoresist pattern was performed, and it was confirmed that the photoresist pattern did not peel.
[Example 2]
A copper-clad laminate was produced under the same conditions as in Example 1, except that the amount of benzotriazole in the aqueous solution of the organic rust inhibitor used in the rust preventive treatment step was 0.2% by mass.

  When the contact angle of the copper layer of the obtained copper-clad laminate to pure water was measured, the minimum value was 56 ° and the maximum value was 59 °.

A long-term storage test of the copper-clad laminate was performed, and it was confirmed that the copper-clad laminate did not rust. Further, a peeling test of the photoresist pattern was performed, and it was confirmed that the photoresist pattern did not peel.
[Example 3]
A copper-clad laminate was produced under the same conditions as in Example 1, except that the amount of benzotriazole in the aqueous solution of the organic rust inhibitor used in the rust prevention treatment step was 0.05% by mass.

  When the contact angle of the copper layer of the obtained copper-clad laminate to pure water was measured, the minimum value was 47 ° and the maximum value was 52 °.

The copper-clad laminate was subjected to a long-term storage test, and it was confirmed that it did not rust. Further, a peeling test of the photoresist pattern was performed, and it was confirmed that the photoresist pattern did not peel.
[Example 4]
A copper-clad laminate was produced under the same conditions as in Example 1 except that the amount of benzotriazole in the aqueous solution of the organic rust inhibitor used in the rust prevention treatment step was changed to 0.6% by mass.

  When the contact angle of the copper layer of the obtained copper-clad laminate to pure water was measured, the minimum value was 65 ° and the maximum value was 68 °.

The copper-clad laminate was subjected to a long-term storage test, and it was confirmed that it did not rust. Further, a peeling test of the photoresist pattern was performed, and it was confirmed that the photoresist pattern did not peel.
[Comparative Example 1]
A copper-clad laminate was produced under the same conditions as in Example 1, except that the amount of benzotriazole in the aqueous solution of the organic rust inhibitor used in the rust prevention treatment step was 0.9% by mass.

  When the contact angle of the copper layer of the obtained copper-clad laminate to pure water was measured, the minimum value was 85 ° and the maximum value was 89 °.

  The copper-clad laminate was subjected to a long-term storage test, and it was confirmed that it did not rust.

However, when a pattern peeling test of the photoresist was performed, peeling of the photoresist pattern was confirmed as shown in FIG.
[Comparative Example 2]
The same as Example 1 except that the amount of benzotriazole in the aqueous solution of the organic rust inhibitor used in the rust prevention treatment step was 0.6% by mass, and drying with heated air was not performed in the rust prevention treatment step. Under the conditions, a copper-clad laminate was produced.

  When the contact angle of the copper layer of the obtained copper-clad laminate with respect to pure water was measured, the minimum value was 66 ° and the maximum value was 84 °, showing a larger variation than the other Examples and Comparative Examples.

  The copper-clad laminate was subjected to a long-term storage test, and it was confirmed that it did not rust.

However, a peeling test of the photoresist pattern was performed, and it was confirmed that the photoresist pattern was partially peeled.
[Comparative Example 3]
A copper-clad laminate was prepared under the same conditions as in Example 1 except that the application of the organic rust inhibitor and the washing after the application of the organic rust inhibitor were not performed.

  The minimum value of the contact angle of the copper layer of the obtained copper-clad laminate with respect to pure water was 39 °, and the maximum value was 40 °.

  In addition, when a long-term storage test of the copper-clad laminate was performed, discoloration due to rusting was confirmed with the naked eye.

  However, when a photoresist pattern peeling test was performed, no photoresist pattern peeling was confirmed.

  These results are summarized in Table 1.

From the above, in Examples 1 to 4 in which the contact angles of the second surface of the copper layer with respect to pure water are all in the range of 45 ° or more and 80 ° or less, rust of the copper-clad laminate was not observed, Also, peeling of the photoresist pattern was not observed.

  On the other hand, in Comparative Example 3 in which the contact angle of the copper layer surface with pure water showed a value of less than 45 °, the discoloration due to rust showed a value exceeding 80 ° in at least one measurement point. In Example 2, occurrence of peeling of the photoresist pattern was confirmed.

10, S copper-clad laminate 11 resin film 12 copper layer 12a first surface 12b second surface

Claims (12)

A resin film,
A copper layer formed on at least one side of the resin film and having a first surface facing the resin film and a second surface opposite to the first surface; ,
A copper-clad laminate, wherein the second surface of the copper layer has been subjected to a rust-proof treatment, and a contact angle of the rust-proofed second surface to pure water is 45 ° or more and 80 ° or less.   The copper clad laminate according to claim 1, wherein an organic rust preventive is used as a rust preventive when performing the rust preventive treatment on the second surface.   The copper clad laminate according to claim 2, wherein the organic rust inhibitor contains an azole.   The copper clad laminate according to claim 3, wherein the organic rust inhibitor contains benzotriazole.   The copper clad laminate according to any one of claims 1 to 4, wherein a thickness of the copper layer is 0.1 µm or more and 20 µm or less.   The copper clad laminate according to any one of claims 1 to 5, wherein the resin film is a polyimide film. A resin film,
A copper layer formed on at least one surface side of the resin film and having a first surface facing the resin film, and a second surface opposite to the first surface; A rustproofing step of rustproofing the second surface of the copper-clad laminate,
The method for producing a copper-clad laminate, wherein the rustproofing process is performed such that a contact angle of the second surface with pure water is 45 ° or more and 80 ° or less.   The method for producing a copper-clad laminate according to claim 7, wherein an organic rust preventive is used as the rust preventive in the rust preventive process.   The method for producing a copper-clad laminate according to claim 8, wherein the organic rust inhibitor contains an azole.   The method for manufacturing a copper-clad laminate according to claim 9, wherein the organic rust inhibitor contains benzotriazole.   The method for producing a copper-clad laminate according to any one of claims 8 to 10, wherein the organic rust inhibitor contains alcohol. A metal seed layer forming step of forming a metal seed layer on at least one surface side of the resin film by a dry plating method,
A copper thin film layer forming step of forming a copper thin film layer on the metal seed layer by a dry plating method,
The method for producing a copper-clad laminate according to any one of claims 7 to 11, comprising a copper plating layer forming step of forming a copper plating layer by an electroplating method and / or an electroless plating method.