TWI510673B - 2-layer flexible substrate and manufacturing method thereof - Google Patents

Description

Two-layer flexible substrate and method of manufacturing same

The present invention relates to a two-layer flexible substrate and a method of manufacturing the same, and more particularly to forming an underlying metal layer (hereinafter sometimes referred to as a "seed layer") by dry plating on an insulator film, and then A two-layer flexible substrate having less pinholes and concave defects when forming a copper layer, and a method of manufacturing the same.

Today, LCDs, mobile phones, digital cameras, and various types of electrical equipment are required to be thin, small, and lightweight. The electronic components mounted thereon are miniaturized, and the substrates for forming electronic circuits are: rigid boards. A "rigid printed wiring board" and a flexible printed wiring board (hereinafter sometimes referred to as "FPC") which is flexible and flexible.

In particular, FPC is used for flexibility, such as: LCD driver wiring board, HDD (hard disk drive), DVD (digital versatile CD) module, hinge part of mobile phone, etc. Therefore, its demand will increase.

As a user of the FPC material, a copper-clad laminate (hereinafter sometimes referred to as "CCL") in which a copper foil (conductor layer) is adhered to an insulating film such as polyimide or polyester is used.

There are two types of CCL roughly classified. The CCL (usually referred to as "3 layers of CCL", hereinafter referred to as "3 layers of CCL") in which the insulating film and the copper foil (conductor layer) are adhered by an adhesive, and the other insulating film and copper foil (conductor layer) are When the adhesive is not used, CCL (commonly referred to as "two-layer CCL", hereinafter referred to as "two-layer CCL") is directly compounded by a casting method, a lamination method, a metallization method, or the like.

When the "three-layer CCL" is compared with the "two-layer CCL", the three-layer CCL is relatively easy to manufacture, such as an insulating film, an adhesive, and the like, in terms of manufacturing cost, and thus the price is relatively low. . On the other hand, in terms of heat resistance, thin film formation, dimensional stability, and the like, the two-layer CCL is excellent, and it is affected by fine patterning of the circuit and high-density mounting, and although it is high in unit price, it can be made thinner. The demand for the two-tier CCL has gradually expanded.

Furthermore, the method of mounting an IC on an FPC is to form a wiring pattern on the CCL, and then use a COF that penetrates the position of the photodetecting IC of the insulating film to be mainstream, and requires the thinness of the material and the insulating material. Transparency. In this regard, it is also advantageous for the 2-layer CCL.

The manufacturing method of the two-layer CCL having such a feature can be roughly classified into three types. The first type is a method of adhering an insulating film to a copper foil or a rolled copper foil by a casting method. The second method is a method in which an electrolytic copper foil or a rolled copper foil is adhered to an insulating film by a lamination method. The third type is a dry plating method on the insulating film (herein, "dry plating method" means sputtering, ion plating, cluster ion beam method, vacuum evaporation method, In the CVD method or the like, a method is provided in which an underlying metal layer of a thin film is provided on an insulating film, and then copper plating is performed thereon to form a copper layer. The third method is usually called the "metallization method".

Since the metallization method can freely control the thickness of the metal layer by using a dry plating method and a wet plating method (for example, electroplating), the thinning of the metal layer is compared to the casting method or layer. The pressure method is easier. Further, since the interface between the polyimide and the metal layer has high smoothness, it is generally considered to be suitable for a fine pattern.

However, since the CCL obtained by the metallization method has a smooth interface between the metal and the insulating film, the anchoring effect generally used cannot be expected, and the bonding strength of the interface cannot be sufficiently exhibited. problem.

That is, the two-layer CCL formed by the metallization method is subjected to a "PCT Test (Pressure Cooker Test) at a high temperature, high humidity, and high pressure of 121 ° C, 95% RH, and 2 atmospheres for a long time. )), the adhesion strength tends to decrease significantly compared to the initial adhesion strength. Therefore, when drying after the liquid photoresist coating in the pattern forming step is considered, heat of about 100 to 150 ° C is applied, and when bonding or soldering is performed when an IC or the like is mounted on the formed pattern, it is also applied. The heat of about 250 ° C and the wiring formed by patterning are sealed by a sealing resin such as a solder resist, and the conventional two-layer CCL manufactured by the metallization method is not suitable for fine pattern formation and COF mounting at a high temperature. The improvement of heat resistance and moisture resistance is an indispensable issue.

In order to solve such a problem, for example, Patent Document 1 proposes a method of forming a metal alloy layer containing Ni and Cr as a main component as an intermediate layer (seed layer) of an insulating film and a copper layer, but when a finer pattern is formed It is necessary to improve its moisture resistance.

Further, Patent Document 2 discloses a flexible printed circuit board in which a copper thin film made of copper or an alloy containing copper as a main component is directly provided on at least one surface of a plastic film substrate, wherein the copper thin film is provided. The surface layer having a crystal structure and a two-layer structure in which a bottom layer of a polycrystalline structure is provided between the surface layer and the plastic film substrate, and a lattice surface index (200) in an X-ray analysis pattern of the copper thin film The peak intensity is divided by the peak intensity of the lattice plane index (111). The X-ray relative intensity ratio (200) / (111) is 0.1 or less, and the bottom layer is treated with a plasma using a nitrogen-containing mixed gas. A functional group is formed on the plastic film substrate to form a metal composed of copper or an alloy containing copper as a main component, and the metal is chemically bonded to atoms constituting the plastic film substrate to improve moisture resistance. However, this invention is achieved by the control of the lattice plane and the composite effect by the plasma treatment, but it is technically difficult to control the lattice surface, and it is difficult to carry out mass production stably.

Further, in order to form a thin film on the insulating film, a vacuum deposition method, a sputtering method, an ion plating method, or the like is generally used, but a film layer obtained by such a dry plating method usually has a majority. Pinholes of several tens of μm to several hundred μm, so that the underlying metal layer tends to have an exposed portion of the insulator film due to the pinhole.

Conventionally, in such a flexible wiring board, it is preferable that the thickness of the copper conductive film required for wiring is more than 35 μm to 50 μm. However, since the width of the formed wiring is also about several hundred μm, it is rarely caused. The presence of tens of μm pinholes causes defects in the wiring portion.

However, when it is desired to obtain the flexible wiring board having the narrow-width and narrow-pitch wiring portions which are the object of the present invention, as described above, it is preferable that the thickness of the copper film for forming the wiring portion is 15 μm or less, preferably 8 μm or less. It is desirable to have an extremely thin thickness of about 5 μm, which increases the possibility of occurrence of defects in the wiring portion.

In this case, the flexible wiring board is manufactured by a subtractive method using a two-layer flexible substrate in which a copper film layer having a desired thickness is formed on an insulating film on which an underlying metal layer is formed. As an example, the formation of the wiring portion pattern is carried out in accordance with the following procedure.

(1) A photoresist layer having a desired wiring portion pattern of a copper conductor layer that shields only the wiring portion but exposes the non-wiring portion is provided on the copper conductor layer.

(2) The exposed copper conductor layer is subjected to a chemical etching treatment to be removed.

(3) Finally, the photoresist layer is peeled off.

Therefore, when a substrate having a thickness of, for example, a very thin copper film layer of 5 μm is used, for example, a narrow wiring width and a narrow wiring pitch wiring board having a wiring width of 15 μm and a wiring pitch of 30 μm are produced, and the underlying metal on the substrate is subjected to dry plating treatment. Among the pinholes produced on the layer, the size of the thicker ones will be on the order of several tens of μm to several hundreds of μm. Therefore, when an electroplated copper film having a thickness of about 5 μm is formed, the exposed portion of the insulator film due to the pinholes can hardly be Since the exposed portion (that is, the defective portion of the conductor layer) is involved in the wiring portion, the wiring portion is defective at the pinhole position and becomes a wiring defect, which may cause the wiring portion to be poorly connected.

Therefore, Patent Document 3 discloses a technique for specifying the number of pinholes of a metal polyimide film laminate. However, Patent Document 3 does not disclose a pinhole of a vapor deposition film, but defines a pinhole after copper plating, and does not disclose any pinholes between the vapor deposition film and the underlying metal layer.

Further, as a method for solving the above problem, Patent Document 4 discloses that a base metal layer is formed on a thin film by a dry plating method, and then a copper coating layer by electroless plating is applied as an intermediate metal layer. A method of coating an exposed portion of an insulator film due to a pinhole.

However, although this method can surely eliminate the exposed portion of the insulator film due to the pinhole, on the other hand, it has been known that the plating solution and the pretreatment liquid used in the electroless copper plating process are The various pinhole portions of the formed size penetrate between the insulator film and the underlying metal layer, which may become the adhesion to the underlying metal layer and the adhesion of the conductor layer by the formed copper plating. The reasons for the obstacles are not sufficient solutions. Further, even if the exposed portion of the insulating film is buried by the electroplated copper, the adhesion between the insulating film and the copper layer is low. Therefore, if the underlying metal layer has pinholes, the adhesion failure and the insulation reliability are lowered.

[Advanced technical literature] [Patent Literature]

Patent Document 1: Japanese Patent Laid-Open No. 2006-13152

Patent Document 2: Japanese Patent No. 3563730

Patent Document 3: Japanese Patent Laid-Open No. Hei 11-92917

Patent Document 4: Japanese Patent Laid-Open No. 10-195668

SUMMARY OF THE INVENTION The object of the present invention is to solve the above problems in the manufacture of a two-layer flexible substrate using a dry plating method, and to provide that there is no pinhole generated when an underlying metal layer is formed by dry plating on an insulator film. The two-layer flexible substrate which is excellent in adhesion, corrosion resistance and water resistance between the insulator film and the underlying metal layer is less likely to cause defects in the copper foil film layer and the copper layer, and the underlying metal layer is less likely to be damaged. A two-layer flexible substrate with fine pattern formation, COF mounting, and a method of manufacturing the same.

The present inventors have found that a copper thin film having a desired layer thickness is formed on the underlying metal layer by using at least one surface of the insulating film, without using an adhesive, by using a dry plating method to form an underlying metal layer. a two-layer flexible substrate of a layer and/or a copper layer, wherein the insulator film is subjected to a surface treatment, and the amount of the oligomer is a two-layer flexible substrate having 70% or less of the amount of the oligomer before the surface treatment, The copper film layer and the copper layer are not damaged due to pinholes generated when the underlying metal layer is formed, and the underlying metal layer is less defective, and the adhesion between the insulator film and the underlying metal layer and corrosion resistance are obtained. Further, the two-layer flexible substrate excellent in water resistance and the flexible wiring board having narrow-width and narrow-pitch wiring portions can be applied to the present invention.

According to a first aspect of the present invention, a two-layer flexible substrate is formed on at least one surface of an insulating film, and when an adhesive is not passed, a bottom metal layer is formed by dry plating, and a dry type is used on the underlying metal layer. A method of forming a copper film layer by a plating method, wherein the insulator film is subjected to a surface treatment on at least one of the surfaces, and the amount of the oligomer after the surface treatment is applied to only one of the insulating film is 70% of the amount of the oligomer before the surface treatment. the following.

In the second invention of the present invention, the copper thin film layer has a thickness of 50 nm to 500 nm, and has no pinholes having a diameter exceeding 30 μm, and a pinhole having a diameter of 5 μm or more and 30 μm or less is 45,000 or less per square meter.

According to a third aspect of the invention, the two-layer flexible substrate according to the first or second aspect of the invention, wherein the copper wet plating layer is formed on the copper thin film layer by wet plating.

According to a fourth aspect of the present invention, the copper wet plating layer of the third invention has a thickness of 0.5 μm to 12 μm, and has no concave defects having a diameter or a maximum defect length of more than 20 μm, and a concave defect having a diameter or a maximum defect length of 10 μm or more and 20 μm or less. It is 2,200 or less per 1 square meter.

According to a fifth aspect of the present invention, in the second aspect of the invention, the second layer flexible substrate has a layer thickness of 5 nm to 50 nm and contains 6% by weight to 22% by weight of an additive element mainly composed of chromium. The rest is formed of a nickel-chromium alloy composed of nickel, and the thickness of the conductor layer (copper layer) composed of the copper thin film layer and the copper wet plating layer provided on the underlying metal layer is 50 nm. ~12μm.

According to a sixth aspect of the invention, the insulator film of the first to fifth inventions is a polyimide film, a polyamide film, a polyester film, a polytetrafluoroethylene film, a polyphenylene sulfide film, or a poly A resin film selected from the group consisting of an ethylene naphthalate film and a liquid crystal polymer film.

According to a seventh aspect of the present invention, in the surface treatment according to the first to sixth aspects of the invention, the surface of the insulator film is subjected to a plasma discharge treatment using a DC voltage of 1500 V to 3000 V in an inert atmosphere at a pressure of 0.8 Pa to 4.0 Pa.

According to an eighth aspect of the present invention, in the inert environment of the surface treatment according to the seventh aspect of the invention, the PCT peel strength after the surface treatment is 70% or more of the initial peel strength.

According to a ninth aspect of the present invention, in the surface treatment according to the first to sixth aspects of the invention, the surface of the insulator film is subjected to a plasma discharge treatment using a high-frequency voltage of 800 V to 2000 V in an inert atmosphere at a pressure of 0.8 Pa to 4.0 Pa.

According to a tenth aspect of the present invention, the surface treatment inert environment of the ninth invention is a nitrogen atmosphere, and the PCT peel strength after the surface treatment is 70% or more of the initial peel strength.

According to an eleventh aspect of the present invention, in the at least one surface of the insulating film, the underlying metal layer is formed by dry plating without passing through the adhesive, and the copper thin film layer is formed by dry plating on the underlying metal layer. A method for producing a two-layer flexible substrate, wherein a plasma of 2 to 100 seconds is applied between the paired discharge electrodes of the plasma electrode under an inert atmosphere of a pressure of 0.8 Pa to 4.0 Pa on the surface of the insulator film After the surface treatment of the discharge, an underlying metal layer is formed.

According to a twelfth aspect of the present invention, in the surface treatment by the plasma discharge of the eleventh aspect of the invention, a direct current voltage of 1500 V to 3000 V is applied between the discharge electrodes of the plasma electrode.

According to a thirteenth aspect of the invention, in the surface treatment by the plasma discharge of the eleventh aspect of the invention, the high-frequency voltage of 800 V to 2000 V is applied between the discharge electrodes of the plasma electrode.

According to a fourteenth aspect of the present invention, in the at least one surface of the insulating film, the underlying metal layer is formed by dry plating without passing through the adhesive, and the copper thin film layer is formed by dry plating on the underlying metal layer. A method of producing a two-layer flexible substrate according to the eighth aspect of the present invention, wherein a surface voltage of a plating film of 0.8 Pa to 4.0 Pa is applied to apply a DC voltage of 1500 V to 3000 V between the paired discharge electrodes of the plasma electrode. After the surface treatment of the plasma generated in 2 to 100 seconds, an underlying metal layer is formed.

According to a fifteenth aspect of the present invention, in the at least one surface of the insulating film, the underlying metal layer is formed by dry plating without passing through the adhesive, and the copper thin film layer is formed by dry plating on the underlying metal layer. According to a tenth aspect of the invention, in the method of producing a two-layer flexible substrate, the surface of the insulating film is applied with a high frequency of 800 V to 2000 V between the paired discharge electrodes of the plasma electrode under a nitrogen atmosphere of a pressure of 0.8 Pa to 4.0 Pa. After the surface treatment of the plasma generated by the voltage for 2 to 100 seconds, an underlying metal layer is formed.

According to a sixteenth aspect of the invention, the dry plating method of the eleventh to fifteenth invention is a vacuum vapor deposition method, a sputtering method, and an ion plating method.

According to a seventeenth aspect of the invention, the insulator film of the eleventh to sixteenth aspects of the invention is a polyimide film, a polyamide film, a polyester film, a polytetrafluoroethylene film, a polyphenylene sulfide film, or a polysiloxane film. A resin film selected from the group consisting of an ethylene naphthalate film and a liquid crystal polymer film.

According to the present invention, the copper film layer and the copper wet plating layer are not damaged due to the pinholes generated when the underlying metal layer is formed, and the underlying metal layer is less defective, and between the insulator film and the underlying metal layer. A two-layer flexible substrate excellent in adhesion and corrosion resistance. The two-layer flexible substrate is also suitable for a flexible wiring board having a narrow-width and narrow-pitch wiring portion, and thus exhibits an industrially remarkable effect.

1.2 layer flexible substrate

The two-layer flexible substrate of the present invention is formed on at least one surface of the insulating film, and is provided with a bottom metal layer by dry plating and a copper film on the underlying metal layer without passing through an adhesive. The structure of the layer is characterized in that the insulator film is subjected to a surface treatment such that the amount of the oligomer becomes 70% or less of the amount of the oligomer before the surface treatment, and the surface of the insulator film is subjected to surface treatment. On the other hand, the amount of the oligomer before the surface treatment is 70% or less, and the generation of coarse pinholes can be suppressed.

Furthermore, the two-layer flexible substrate of the present invention preferably has a copper thin film layer having a thickness of 50 nm to 500 nm, and has no pinholes having a diameter of 30 μm, and a pinhole having a diameter of 5 μm to 30 μm is 45,000 or less per square meter. .

1-1. Copper film layer

The thickness of the copper thin film layer is preferably from 50 nm to 500 nm.

If the thickness of the copper foil film layer is less than 50 nm, when a copper wet plating layer is formed on the surface of the copper film layer by a copper plating method which is one of the wet plating methods, the resistance of the copper film layer is The value is increased and the plating appearance of the copper layer surface is deteriorated. Further, when the copper wet plating layer is formed by the electroplating copper method, the copper thin film layer functions as a cathode, and the resistance value of the copper thin film layer poses a problem. On the other hand, when the thickness of the copper thin film layer exceeds 500 nm and the film formation is performed, the pinholes between the copper thin films are reduced. However, it is time-consuming to form the copper thin film layer by dry plating, and the economy is inferior.

In general, the thicker the copper thin film layer and the copper wet plating layer are, the more copper can be grown and the pinholes are buried, so that the pinholes are small or even small. Therefore, compared with the dry plating method, a copper wet plating layer is provided on the surface of the copper thin film layer by a wet plating method in which the film formation speed is relatively fast, and a two-layer flexible substrate is produced. The two-layer flexible substrate has a small number of pinholes on the surface by wet plating. However, even if the pinholes on the surface of the two-layer flexible substrate are buried, the pinholes of the underlying metal layer and the copper thin film layer are not buried.

Therefore, when the size and number of pinholes of the underlying metal layer and the copper thin film layer are not suppressed, the wiring portion pattern having a narrow wiring pitch is formed, and the wiring portion without the underlying metal layer is easily exposed, resulting in wiring defects, even if This is not the reason why the wiring part is poorly connected.

Further, the pinholes of the copper thin film layer are buried by wet plating, but if there is a pinhole of the copper thin film layer, the underlying metal layer is exposed to the atmosphere before wet plating, and thus the underlying metal layer This deteriorates, causing wiring defects and poor wiring contact.

Therefore, in the copper thin film layer of the present invention, even if it has a pinhole, it is preferable that the pinhole having a diameter of 5 μm to 30 μm is in a range of 45,000 or less per 1 square meter. In addition, pinholes having a diameter of less than 5 μm are less likely to cause wiring defects and poor adhesion, and detection is also difficult, and thus the number is not specified.

By using the above structure, it is possible to obtain a defect in the copper film portion which is not caused by pinholes generated when the underlying metal layer is formed, and the underlying metal layer has less defects, and the adhesion between the insulator film and the underlying metal layer is obtained. A two-layer flexible substrate excellent in corrosion resistance and water resistance.

1-2. Surface treatment of insulator film (substrate)

The surface treatment of the insulating film of the substrate is carried out using a plasma treatment. The surface treatment can be performed on one side of the insulator film, but it is more effective for double-sided implementation.

The treatment conditions are in an inert environment at a pressure of 0.8 Pa to 4.0 Pa. In an inert environment with a pressure less than 0.8 Pa, the plasma discharge is not easy to stabilize. If the treatment is too strong under an inert environment of 4.0 Pa, the wrinkling of the insulating film may occur during processing. Therefore, it is not good.

A DC voltage of 1500 V to 3000 V is applied between the paired discharge electrodes of the plasma electrode, and DC plasma (DC plasma) treatment is performed. If the DC voltage is less than 1500 V, the treatment by the plasma is too weak, and the initial adhesion strength does not rise. If it exceeds 3000 V, the treatment becomes too strong, and the insulation film is likely to wrinkle during the treatment. The deformation and the reverse result in a result of lowering the heat-resistant adhesive strength and the PCT peel strength, and thus are less preferable.

A high frequency voltage of 800V to 2000V is applied between the paired discharge electrodes of the plasma electrode, and high frequency plasma (RF plasma) treatment is performed. If the high-frequency voltage is less than 800 V, the treatment by the plasma is too weak, and the initial adhesion strength does not rise. If it exceeds 2000 V, the treatment becomes too strong, so that the insulating film tends to occur during the treatment. Wrinkles and deformations are therefore less preferred.

Here, the term "in an inert atmosphere" means a Group 18 gas such as nitrogen or argon, and may be a mixed gas of nitrogen and argon. In particular, when the surface treatment is performed by plasma in a nitrogen atmosphere, the PCT peel strength can be made 70% or more of the initial peel strength.

The processing time by plasma discharge is preferably from 2 seconds to 100 seconds. If the treatment time of the plasma discharge is less than 2 seconds, the treatment is too weak, which does not contribute to the increase of the initial adhesion strength. If the treatment is continued for more than 100 seconds, the influence is excessive, and the insulating film is likely to wrinkle and deform. The result is that the heat-resistant adhesion strength and the PCT adhesion strength are lowered, which is less preferable. On the other hand, from the viewpoint of productivity, a long processing time of more than 100 seconds is also poor.

The larger the amount of the insulator thin film-based oligomer of the substrate, the more the pinhole of the copper thin film layer increases.

When the surface of one surface of the insulator film is subjected to surface treatment, the amount of the surface-treated insulator film oligomer is preferably 70% or less compared with the amount of the oligomer before the surface treatment. Further, when the surface of the insulator film is subjected to surface treatment on both sides, the amount of the oligomer of the surface-treated insulator film is preferably 35% or less compared with the amount of the oligomer before the surface treatment.

The reason why the amount of oligomers is reduced by the surface treatment is that the oligomer is removed by surface treatment. Here, the "oligomer" is a molecule having a molecular weight of from 300 to 14,000, and when an insulator film is produced, molecules which remain in the film are not sufficiently polymerized. The amount of the oligomer was determined by measuring the amount of the oligomer as follows. The oligomer is extracted from the insulator film using a solvent such as tetrahydrofuran, and the molecular weight distribution can be measured by size exclusion chromatography (SEC method).

1-3. Underlying metal layer

The layer thickness of the underlying metal layer is preferably 5 nm to 50 nm.

If the thickness of the underlying metal layer formed by the nickel-chromium alloy mainly using chromium as an additive element obtained by the dry plating method is less than 5 nm, the long-term adhesion of the underlying metal layer will be obtained even after the subsequent processing steps. problem appear. In addition, when the thickness of the underlying metal layer is less than 5 nm, the etching liquid may be infiltrated during the wiring process, and the wiring portion may be floated or the like, and the problem that the wiring peeling strength is remarkably lowered may be caused, which is not preferable.

On the other hand, when the thickness of the underlying metal layer exceeds 50 nm, it is difficult to remove the underlying metal layer when the wiring portion is processed, and cracking, warpage, or the like may occur, and the adhesion strength may be lowered. Therefore, it is not good. Further, if the layer thickness is thicker than 50 nm, it is still difficult to perform etching because it is difficult to perform etching.

The composition of the underlying metal layer must be from 12% by weight to 22% by weight in terms of heat resistance and corrosion resistance. In other words, when the chromium ratio is less than 12% by weight, the heat resistance is lowered. On the other hand, when the chromium ratio exceeds 22% by weight, the removal of the underlying metal layer is difficult when the wiring portion is processed, which is disadvantageous. . Further, in the nickel-chromium alloy, a transition metal element can be appropriately added in accordance with the purpose of the purpose for the purpose of improving heat resistance and corrosion resistance.

In the case of such an underlying metal layer, in the case of the two-layer flexible substrate of the present invention, the thickness of the underlying metal layer is preferably 15 nm to 50 nm.

Further, the underlying metal layer is preferably composed of an alloy having a chromium ratio of 4% by weight to 22% by weight, and further containing 5% by weight to 40% by weight of molybdenum, and the balance being nickel.

The chromium ratio is 4% by weight to 22% by weight, which is necessary to prevent the heat-resistant peeling strength from being significantly lowered due to thermal deterioration. If the chromium ratio is less than 4% by weight, even if molybdenum is added, the heat-resistant peeling strength cannot be prevented due to heat. Degraded and significantly reduced, and thus less preferred. Further, if the chromium ratio is more than 22% by weight, etching tends to be difficult and thus it is not preferable. Therefore, in the case of chromium, it is more preferably 4% by weight to 15% by weight, particularly preferably 5% by weight to 12% by weight.

Next, in order to improve the corrosion resistance and the insulation reliability, the molybdenum ratio is preferably 5% by weight to 40% by weight. If the proportion of molybdenum is less than 5% by weight, the effect of addition does not appear, and corrosion resistance and insulation reliability are not improved, which is not preferable. Moreover, when the molybdenum ratio exceeds 40% by weight, the heat-resistant peel strength tends to be extremely lowered, which is not preferable.

Further, in the case of a nickel-based alloy target, if the nickel ratio is more than 93% by weight, the sputtering target itself becomes a ferromagnetic body, and when the film is formed by magnetron sputtering, the film formation speed is lowered. Therefore, it is less preferable, and when the underlying metal layer of the present invention is formed by sputtering, since the target composition of the sputtering is 93% by weight or less of the amount of nickel, even when film formation is performed by magnetron sputtering, A good film formation rate can be obtained. Further, in the nickel-chromium-molybdenum alloy, a transition metal element can be appropriately added in accordance with the purpose of the purpose for the purpose of improving heat resistance and corrosion resistance.

Further, in the underlying metal layer, in addition to the nickel-chromium-molybdenum alloy, there is a possibility that 1% by weight or less of unavoidable impurities contained in the target material is taken in or the like.

Further, in the formation of the underlying metal layer and the copper thin film layer, dry plating is used, and in the dry plating method, vacuum evaporation, sputtering, or ion plating is preferably used. By.

1-4. Insulator film (substrate)

Further, in the two-layer flexible substrate of the present invention, the insulating film of the substrate is preferably a polyimide film, a polyamide film, a polyester film, a polytetrafluoroethylene film, or a polycrystalline film. A resin film selected from the group consisting of a phenylene sulfide film, a polyethylene naphthalate film, and a liquid crystal polymer film.

For example, an insulator film having a film thickness of 25 to 75 μm is preferably used. Further, since an inorganic material such as glass fiber is an obstacle to laser processing and chemical etching, it is preferable not to use a substrate containing an inorganic material.

1-5. Copper layer (conductor layer)

In the two-layer flexible substrate of the present invention, a copper thin film layer is formed on the underlying metal layer by dry plating, and then a copper wet plating layer is formed on the copper thin film layer by wet plating, and the layer is further laminated. The copper thin film layer and the copper wet plating layer are formed by a copper layer having a thickness of 10 nm to 12 μm.

When the copper layer is formed by only the dry plating method, the dry plating method is either a vacuum evaporation method, a sputtering method, or an ion plating method, and may be formed in comparison with the wet plating method. The film is slower and more suitable for forming a thinner copper layer. On the other hand, after the copper thin film layer is formed by the dry plating method, the copper layer is formed by wet plating on the copper thin film layer, and it is suitable to form a thick copper layer in a short time, which contributes to productivity improvement.

When the outermost surface of the two-layer flexible substrate of the present invention is a copper thin film layer, the number of pinholes having a diameter of 5 μm to 30 μm is suppressed to 45,000 or less per square meter, and when the outermost surface is a copper wet plating layer, The number of concave defects having a diameter or a maximum defect length of 10 μm to 20 μm is suppressed to 2,200 or less per 1 square meter, which is suitable for producing a flexible wiring board having narrow pitch wiring.

2.2 Layered flexible substrate manufacturing method

Hereinafter, a method of producing a two-layer flexible substrate of the present invention will be described in detail.

In the present invention, a polyimide film, a polyamide film, a polyester film, a polytetrafluoroethylene film, a polyphenylene sulfide film, or a polyethylene naphthalate film are used as a substrate. An insulator film of a resin film selected from the group consisting of an ester film and a liquid crystal polymer film, on one or both sides thereof, forming an underlying metal layer without passing through an adhesive, and forming a copper film on the underlying metal layer Floor.

The insulator film of the substrate usually contains moisture, and it is necessary to perform atmospheric drying or vacuum drying before forming the underlying metal layer composed of a nickel-chromium alloy by dry plating, and to remove moisture present in the insulator film. If this action is insufficient, the adhesion to the underlying metal layer will be deteriorated.

When the underlying metal layer is formed by dry plating, for example, when a bottom metal layer is formed using a roll-to-roll coiling apparatus, a target having a bottom metal layer is mounted on the sputtering cathode.

First, vacuum evacuation is performed in a sputtering apparatus equipped with an insulator film, and a mixed gas of nitrogen or argon or nitrogen and argon is introduced, and the apparatus is maintained in an inert atmosphere at a pressure of 0.8 Pa to 4.0 Pa. A 1500V~3000V DC voltage or a high frequency voltage of 800V~2000V is applied between the paired discharge electrodes of the plasma electrode, and the surface treatment is performed by using plasma for 2 seconds to 100 seconds.

Next, argon gas is introduced, and the inside of the apparatus is maintained at about 1.3 Pa, and the winding film attached to the winding roller and the wound roller in the apparatus are conveyed at a speed of about 3 m per minute while being guided from the cathode. The connected sputtering is supplied with a DC power source to start the sputtering discharge, and an underlying metal layer composed of a nickel-chromium alloy or a nickel-chromium-molybdenum alloy is formed on the insulator film.

The copper thin film layer was formed in the same manner as in the case of the underlying metal layer, and a copper thin film layer was formed by using a sputtering apparatus in which a copper target was mounted on a sputtering cathode. At this time, the underlying metal layer and the copper thin film layer are preferably formed continuously in the same vacuum chamber. After the underlying metal layer is formed, the film is taken out into the atmosphere, and when a copper thin film layer is formed by using another sputtering device, the film must be formed. Adequate dehydration was performed beforehand.

Further, when the copper thin film layer is formed by the dry plating method and the copper wet plating layer is formed by the wet plating method on the copper thin film layer, for example, electroless copper plating treatment is preferably performed. In the electroless plating treatment, an electroless copper plating layer is formed on the entire flexible substrate, and even if there is a pinhole, the exposed surface is covered and the entire flexible substrate surface is formed into a good conductor. Thereby, the influence of the pinhole can be suppressed. However, when electroless copper plating is performed, it is necessary to pay attention to the penetration caused by the electroless plating solution and its pretreatment liquid and determine the conditions.

In addition, the layer thickness of the copper-plated wet plating layer formed by the electroless copper plating solution is as long as the defects caused by the pinholes on the repairable substrate surface are treated by the electroplated copper plating solution. The layer thickness is not to be dissolved by the plating of the copper plating solution, and is preferably in the range of 0.01 μm to 1.0 μm.

The substrate on which the electroless copper plating wet plating layer has been formed is formed as a copper wet plating layer capable of forming a final desired layer thickness, and the electroplated copper treatment is performed to obtain a metal layer which is not affected by the underlying metal layer. A two-layer flexible substrate having a good influence on various pinholes and having a high degree of adhesion. Further, the electroplating copper treatment performed in the present invention may be carried out by various conditions of the electroplating copper method which is carried out by a usual method.

Accordingly, the layer thickness of the copper wet plating layer formed on the underlying metal layer and the copper thin film layer is preferably 12 μm or less. The reason for setting the layer thickness is a wiring board capable of obtaining a narrow wiring width and a narrow wiring pitch.

Further, whether or not the copper wet plating layer is formed by wet plating on the surface of the copper thin film layer is appropriately selected in accordance with the method of manufacturing the wiring portion pattern.

For example, when the wiring portion pattern is formed by a known removal method, the wiring portion is formed by the underlying metal layer, the copper thin film layer, and the copper wet plating layer, and thus it is necessary to form a copper wet plating layer. It is required to be the layer thickness required for the wiring portion. Here, the "removal method" is to provide a photoresist layer on the surface of a copper layer of a two-layer flexible substrate, and to provide a mask having a predetermined wiring pattern on the photoresist layer, and to irradiate ultraviolet rays from above. After exposure and development, an etching mask for etching an unnecessary copper layer or the like is obtained, and then the exposed copper layer is etched and removed, and then the remaining photoresist layer is removed. A method of forming a wiring portion pattern by etching the underlying metal layer as a place where the wiring portion is not required.

On the other hand, when the wiring portion pattern is formed by the semi-additive method, the copper wet plating layer may be provided on the copper thin film layer by wet plating, or may not be provided. The term "semi-addition method" as used herein refers to a metal layer of a two-layer flexible substrate (a metal layer composed of an underlying metal layer and a copper thin film layer, or an underlying metal layer, a copper thin film layer, and a copper wet plating). a photoresist layer is disposed on a surface of the metal layer of the layer, and a mask having a predetermined wiring pattern is disposed on the photoresist layer, and then ultraviolet rays are irradiated from above to be exposed, and developed to obtain a metal layer. A plating mask is formed by plating copper on the surface to form a wiring portion, and a metal layer exposed to the opening is used as a cathode, and a wiring portion is formed by electroplating, and then the photoresist layer is removed, and then soft etching is performed to remove A method of forming a wiring portion pattern by completing the wiring portion by removing the metal on the surface of the two unnecessary flexible substrates other than the wiring portion.

[Examples]

Hereinafter, the present invention will be described in detail by way of examples, but the invention is not limited to the examples. The measurement of each characteristic was carried out using the means shown below.

The pinhole is measured by a method of penetrating the layered metal layer and the copper film layer obtained by the dry plating method, and then measuring the size by an optical microscope, and measuring a pinhole having a diameter of 5 μm to 30 μm. The number of each square meter.

The method for evaluating the amount of oligomers is to extract the plasma-treated insulating film by using tetrahydrofuran, and then extract the extract using size exclusion chromatography (SEC method) to determine the proportion of oligomers having a molecular weight of 380 to 13500, and to plasma. The value before the treatment was set to 100%, and was compared and regarded as "amount of oligomer".

The method for measuring the peel strength was carried out in accordance with the method according to IPC-TM-650 and NUMBER2.4.9, and was regarded as "initial peel strength". However, the wire width was set to 1 mm, and the peeling angle was set to 90°. The wire is formed by a removal method. Further, the index of heat resistance was obtained by placing a film substrate on which a 1 mm wire film was formed in an oven at 150 ° C for 168 hours, taking it out, and placing it until it became room temperature, and evaluating it by 90° peel strength, and regarded it as " Heat peel strength".

The index of moisture resistance is obtained by placing a film substrate having a 1 mm wire film in a hot press at 121 ° C and 2 atm for 96 hours, taking it out and placing it at room temperature, and evaluating the peel strength by 90°. And regarded as "PCT Peel Strength".

The measurement method of the concave defect was performed on the surface of the copper wet plating layer obtained by the plating method, and observed using an optical microscope, and the size of the concave defect was measured.

When the concave defect is circular, the number of each square meter of the diameter of 10 μm to 20 μm is measured. When the concave defect is other than the circular shape, the maximum length of the defective portion of the concave defect is regarded as the "maximum defect". "Long", the number of concave defects per 1 square meter from 10 μm to 20 μm was measured.

(Comparative Example 1)

First, Comparative Example 1 shows the characteristics of a two-layer flexible substrate on which film formation is performed without performing plasma treatment.

A first layer of an underlying metal layer was formed on one surface of a 38 μm thick polyimide film (trade name "Kapton 150EN", manufactured by Toray DuPont Co., Ltd.), and the first layer of the underlying metal layer was 20% by weight of Cr- Ni alloy target (manufactured by Sumitomo Metal Mining Co., Ltd.) was formed into a film of a 20 wt% Cr-Ni alloy underlayer metal layer by a DC sputtering method in an Ar environment at a film formation rate of 0.7 nm/sec. The layer thickness was measured using a transmission electron microscope (TEM: manufactured by Hitachi, Ltd.), and a part of the film formed under the same conditions was found to be 0.02 μm. Further, a second layer was formed on the above-mentioned 20% by weight Cr-Ni film, and a Cu target (manufactured by Sumitomo Metal Mining Co., Ltd.) was used to form a copper thin film layer having a thickness of 100 nm by sputtering, and then The film was formed by copper plating to a thickness of 8 μm.

The initial peel strength of the obtained two-layer flexible substrate was 471 N/m, the PCT peel strength was 253 N/m, the number of pinholes of the dry substrate was 76714/m ² , and the amount of the oligomer was 100%, which was not obtained sufficiently. Initial peel strength.

(Example 1)

Hereinafter, the case where the surface treatment by the plasma treatment is performed on the insulating film is exemplified.

A polyimide film having a thickness of 38 μm (manufactured by Toray DuPont Co., Ltd., registered trademark "Kapton 150EN") was applied with a DC voltage of 2000 V for 50 seconds between the paired discharge electrodes of the plasma electrode under a nitrogen pressure of 1.6 Pa. The film formation surface of the underlying metal layer is subjected to a plasma treatment. Next, a first layer of the underlying metal layer is formed on the plasma-treated surface of the polyimide, and the first layer of the underlying metal layer is a 20% by weight Cr-Ni alloy target (Sumitomo Metal Mining Co., Ltd.) In the Ar environment, a 20 wt% Cr-Ni alloy underlayer metal layer was formed into a film by a DC sputtering method at a film formation rate of 0.7 nm/sec.

The layer thickness was measured using a transmission electron microscope (TEM: manufactured by Hitachi, Ltd.), and a part of the film formed under the same conditions was found to be 0.02 μm. Further, a second layer was formed on the 20 wt% Ni-Cr film, and the second layer was formed by using a Cu target (manufactured by Sumitomo Metal Mining Co., Ltd.) to form a copper thin film layer having a thickness of 100 nm by sputtering. The film was formed by copper plating to a thickness of 8 μm.

The obtained two-layer flexible substrate had an initial peel strength of 624 N/m, a PCT peel strength of 434 N/m, and a dry plating (layered body of the underlying metal layer and the copper thin film layer. Hereinafter referred to as "dry plating"). The number of holes was 36,443 / m ² , and there were no pinholes having a diameter exceeding 30 μm, the amount of oligomers was 70%, and the number of concave defects was 1951 / m ² , and there were no concave defects having a diameter or a maximum defect length exceeding 20 μm.

(Example 2)

A polyimide film having a thickness of 38 μm (manufactured by Toray DuPont Co., Ltd., registered trademark "Kapton 150EN") was applied with a DC voltage of 2000 V for 50 seconds between the paired discharge electrodes of the plasma electrode under a nitrogen pressure of 2.4 Pa. The film formation surface of the underlying metal layer is subjected to a plasma treatment. Next, a first layer of the underlying metal layer is formed on the plasma-treated surface of the polyimide, and the first layer of the underlying metal layer is a 20% by weight Cr-Ni alloy target (Sumitomo Metal Mining Co., Ltd.) In the Ar environment, a 20 wt% Cr-Ni alloy underlayer metal layer was formed into a film by a DC sputtering method at a film formation rate of 0.7 nm/sec. The layer thickness was measured using a transmission electron microscope (TEM: manufactured by Hitachi, Ltd.), and a part of the film formed under the same conditions was found to be 0.02 μm. Further, a second layer was formed on the 20 wt% Ni-Cr film, and the second layer was formed by using a Cu target (manufactured by Sumitomo Metal Mining Co., Ltd.) to form a copper thin film layer having a thickness of 100 nm by sputtering. The film was formed by copper plating to a thickness of 8 μm.

The initial peel strength of the obtained two-layer flexible substrate was 635 N/m, the PCT peel strength was 463 N/m, the number of pinholes for dry plating was 15,571 / m ² , and none of the pinholes having a diameter exceeding 30 μm, oligomerization The amount is 56%, the number of concave defects is 1645/m ² , and there are no concave defects with a diameter or a maximum defect length exceeding 20 μm.

(Example 3)

A 38 μm thick polyimine film (trade name "Kapton 150EN", manufactured by Toray DuPont Co., Ltd.) was applied with a DC voltage of 2000 V between the paired discharge electrodes of the plasma electrode for 50 seconds under a nitrogen pressure of 3.1 Pa. The film formation surface of the underlying metal layer is subjected to a plasma treatment. Next, a first layer of the underlying metal layer is formed on the plasma-treated surface of the polyimide, and the first layer of the underlying metal layer is a 20% by weight Cr-Ni alloy target (Sumitomo Metal Mining Co., Ltd.) In the Ar environment, a 20 wt% Cr-Ni alloy underlayer metal layer was formed into a film by a DC sputtering method at a film formation rate of 0.7 nm/sec. The layer thickness was measured using a transmission electron microscope (TEM: manufactured by Hitachi, Ltd.), and a part of the film formed under the same conditions was found to be 0.02 μm. Further, a second layer was formed on the above-mentioned 20% by weight Cr-Ni film, and the second layer was formed by using a Cu target (manufactured by Sumitomo Metal Mining Co., Ltd.) to form a copper thin film layer having a thickness of 100 nm by sputtering. The film was formed by copper plating to a thickness of 8 μm.

The initial peel strength of the obtained two-layer flexible substrate was 632 N/m, the PCT peel strength was 467 N/m, the number of pinholes for dry plating was 8236/m ² , and none of the pinholes having a diameter exceeding 30 μm, oligomerization The amount is 50%, the number of concave defects is 2005/m ² , and there are no concave defects with a diameter or a maximum defect length exceeding 20 μm.

(Comparative Example 2)

Although a 38 μm thick polyimide film (trade name “Kapton 150EN”, manufactured by Toray DuPont Co., Ltd.) is applied, a 500 V DC voltage is applied between the paired discharge electrodes of the plasma electrode for 15 seconds under a nitrogen pressure of 0.7 Pa. However, the discharge was unstable and could not be processed.

(Comparative Example 3)

A 38 μm thick polyimide film (trade name “Kapton 150EN”, manufactured by Toray DuPont Co., Ltd.) was applied at a nitrogen pressure of 4.7 Pa, and a DC voltage of 3500 V was applied between the paired discharge electrodes of the plasma electrode for 6 seconds. Plasma treatment, but wrinkling on the surface, resulting in subsequent performance evaluation can not be carried out.

(Example 4)

A two-layer flexible substrate of Example 4 was produced in the same manner as in Example 1 except that the argon gas pressure was 3.6 Pa, and a DC of 2800 V was applied to the plasma electrode for 6 seconds.

The initial peel strength of the obtained two-layer flexible substrate was 612 N/m, the number of pinholes of dry plating was 7,428 / m ² , and none of the pinholes having a diameter exceeding 30 μm, the amount of oligomers was 50%, and the number of concave defects It has 889 pieces/m ² and has no concave defects with a diameter or a maximum defect length exceeding 20 μm.

(Example 5)

A two-layer flexible substrate of Example 5 was produced in the same manner as in Example 1 except that the argon gas pressure was 1.6 Pa, and a DC of 2,200 V was applied to the plasma electrode to carry out a plasma treatment for 6 seconds.

The initial peel strength of the obtained two-layer flexible substrate was 627 N/m, the number of pinholes of the dry plating was 5142 / m ² , and none of the pinholes having a diameter exceeding 30 μm, and the amount of the oligomer was 70%. Further, the measurement of the concave defects of the two-layer flexible substrate of Example 5 was not carried out.

(Example 6)

A two-layer flexible substrate of Example 6 was produced in the same manner as in Example 1 except that the argon gas pressure was 3.6 Pa, and a DC voltage of 1600 V was applied to the plasma electrode to carry out a plasma treatment for 6 seconds.

The initial peel strength of the obtained two-layer flexible substrate was 626 N/m, the number of pinholes for dry plating was 6428/m ² , and none of the pinholes having a diameter exceeding 30 μm, and the amount of the oligomer was 70%. Further, the measurement of the concave defects of the two-layer flexible substrate of Example 6 was not carried out.

(Comparative Example 4)

Although it was set to an argon gas pressure of 0.7 Pa and a DC voltage of 500 V was applied to the plasma electrode for 6 seconds, the discharge was unstable and could not be processed.

(Comparative Example 5)

Although the argon gas pressure was 4.7 Pa, and the plasma electrode was applied with a direct current of 3,500 V for 6 seconds, the surface was wrinkled, and subsequent evaluation of characteristics could not be performed.

(Example 7)

The same procedure as in Example 1 was carried out except that the mixing gas pressure of 75 vol% argon-25 vol% nitrogen was 1.6 Pa, and the plasma electrode was applied with a direct current of 1800 V for 6 seconds. 2 layers of flexible substrate.

The initial peel strength of the obtained two-layer flexible substrate was 608 N/m, the number of pinholes for dry plating was 8571/m ² , and none of the pinholes having a diameter exceeding 30 μm, the amount of oligomers was 70%, and the number of concave defects It has 1855 pieces/m ² and has no concave defects with a diameter or a maximum defect length exceeding 20 μm.

(Example 8)

The same procedure as in Example 1 was carried out except that the mixing gas pressure of 75 vol% argon-25 vol% nitrogen was 1.6 Pa, and the plasma electrode was subjected to a direct current 2300 V for 6 seconds. 2 layers of flexible substrate.

The initial peel strength of the obtained two-layer flexible substrate was 599 N/m, the number of pinholes for dry plating was 7143/m ² , and none of the pinholes having a diameter exceeding 30 μm, the amount of oligomers was 50%, and the number of concave defects It is 1554 pieces/m ² and has no concave defects with a diameter or a maximum defect length exceeding 20 μm.

(Example 9)

The ninth example was produced in the same manner as in Example 1 except that a mixing gas pressure of 7.5 vol of argon--25 vol% nitrogen was set to 3.6 Pa, and a direct current of 1500 V was applied to the plasma electrode and plasma treatment was performed for 6 seconds. 2 layers of flexible substrate.

The initial peel strength of the obtained two-layer flexible substrate was 593 N/m, the number of pinholes for dry plating was 24,000/m ² , and none of the pinholes having a diameter exceeding 30 μm, the amount of oligomers was 60%, and the number of concave defects It is 1762 pieces/m ² and has no concave defects with a diameter or a maximum defect length exceeding 20 μm.

(Comparative Example 6)

Although the mixing pressure of 75 vol% argon--25 vol% nitrogen was 0.7 Pa, and it was intended to apply a direct current of 500 V to the plasma electrode for 6 seconds, the discharge was unstable and could not be processed.

(Comparative Example 7)

Although it was set to a mixing pressure of 7.5 Pa of 75 vol% argon to 25% by volume of nitrogen, and a direct current of 3500 V was applied to the plasma electrode for 6 seconds, the surface was wrinkled, and subsequent evaluation of characteristics was impossible.

(Embodiment 10)

Example 10 was prepared in the same manner as in Example 1 except that the mixing gas pressure of 50 vol% argon-50 vol% nitrogen was 1.6 Pa, and the plasma electrode was subjected to a direct current 3000 V and a plasma treatment was performed for 50 seconds. 2 layers of flexible substrate.

The initial peel strength of the obtained two-layer flexible substrate was 681 N/m, the number of pinholes of the dry plating was 18,276 / m ² , and none of the pinholes having a diameter exceeding 30 μm, the amount of the oligomer was 70%, and the number of concave defects It is 2076 pieces/m ² and has no concave defects with a diameter or a maximum defect length exceeding 20 μm.

(Example 11)

Example 11 was prepared in the same manner as in Example 1 except that the mixing gas pressure of 50 vol% argon-50% by volume nitrogen was 1.6 Pa, and the plasma electrode was applied with a direct current of 1800 V for 6 seconds. 2 layers of flexible substrate.

The initial peel strength of the obtained two-layer flexible substrate was 572 N/m, the number of pinholes for dry plating was 15,286 / m ² , and none of the pinholes having a diameter exceeding 30 μm, the amount of the oligomer was 30%, and the number of concave defects It is 1861 pieces/m ² and has no concave defects with a diameter or a maximum defect length exceeding 20 μm.

(Embodiment 12)

A sample of Example 12 was produced in the same manner as in Example 1 except that a mixed gas pressure of 3.6 Pa of 50% by volume of argon-50% by volume of nitrogen was applied, and a DC of 2000 V was applied to the plasma electrode for 6 seconds. 2 layers of flexible substrate.

The initial peel strength of the obtained two-layer flexible substrate was 583 N/m, the number of pinholes of the dry plating was 21,286 / m ² , and none of the pinholes having a diameter exceeding 30 μm, the amount of the oligomer was 40%, and the number of concave defects It has 1889 pieces/m ² and has no concave defects with a diameter or a maximum defect length exceeding 20 μm.

(Comparative Example 8)

Although the mixing pressure of 50% by volume of argon-50% by volume of nitrogen was 0.7 Pa, and the direct current of 500 V was applied to the plasma electrode for 6 seconds, the discharge was unstable and could not be processed.

(Comparative Example 9)

Although a mixing pressure of 4.7 Pa of 50% by volume of argon-50% by volume of nitrogen was applied, and a direct current of 3,500 V was applied to the plasma electrode for 6 seconds of plasma treatment, wrinkles appeared on the surface, which prevented subsequent evaluation of characteristics.

(Example 13)

Example 13 was prepared in the same manner as in Example 1 except that the mixing gas pressure of 25% by volume of argon-75 vol% nitrogen was 1.6 Pa, and the plasma electrode was applied with a DC of 1600 V for 6 seconds. 2 layers of flexible substrate.

The initial peel strength of the obtained two-layer flexible substrate was 586 N/m, the number of pinholes for dry plating was 8,857 / m ² , and none of the pinholes having a diameter exceeding 30 μm, the amount of oligomers was 55%, and the number of concave defects There are 1428 / m ² , and there are no concave defects with a diameter or a maximum defect length exceeding 20 μm.

(Example 14)

Example 14 was prepared in the same manner as in Example 1 except that the mixing gas pressure of 25% by volume of argon-75 vol% nitrogen was 1.6 Pa, and the plasma electrode was applied with a direct current of 1800 V for 6 seconds. 2 layers of flexible substrate.

The initial peel strength of the obtained two-layer flexible substrate was 567 N/m, the number of pinholes for dry plating was 11,569 / m ² , and none of the pinholes having a diameter exceeding 30 μm, the amount of oligomers was 50%, and the number of concave defects It has 1276 pieces/m ² and has no concave defects with a diameter or a maximum defect length exceeding 20 μm.

(Example 15)

Example 15 was prepared in the same manner as in Example 1 except that the mixing gas pressure of 5% by volume of argon-75 vol% nitrogen was 3.6 Pa, and a DC of 2000 V was applied to the plasma electrode and plasma treatment was performed for 6 seconds. 2 layers of flexible substrate.

The initial peel strength of the obtained two-layer flexible substrate was 584 N/m, the number of pinholes of the dry plating was 22,429 / m ² , and none of the pinholes having a diameter exceeding 30 μm, the amount of the oligomer was 70%, and the number of concave defects There are 1987 / m ² , and there are no concave defects with a diameter or maximum defect length exceeding 20 μm.

(Comparative Example 10)

Although a mixing pressure of 25% by volume of argon-75 vol% nitrogen was set to 0.7 Pa, and a DC of 500 V was applied to the plasma electrode for 6 seconds, the discharge was unstable and could not be processed.

(Comparative Example 11)

Although a mixing pressure of 7.5 Pa of 25% by volume of argon-75 vol% nitrogen was applied, and a DC of 3500 V was applied to the plasma electrode for 6 seconds, the surface was wrinkled, and subsequent evaluation of characteristics was impossible.

(Embodiment 16)

Example 16 was produced in the same manner as in Example 1 except that the mixing gas pressure of 25% by volume of argon-75 vol% nitrogen was 1.6 Pa, and a high frequency of 600 V was applied to the plasma electrode and plasma treatment was performed for 12 seconds. A two-layer flexible substrate.

The initial peel strength of the obtained two-layer flexible substrate was 598 N/m, the number of pinholes of the dry plating was 9847/m ² , and none of the pinholes having a diameter exceeding 30 μm, the amount of the oligomer was 65%, and the number of concave defects It is 1564 pieces/m ² and has no concave defects with a diameter or a maximum defect length exceeding 20 μm.

(Example 17)

Example 17 was produced in the same manner as in Example 1 except that the mixing gas pressure of 25% by volume of argon-75 vol% nitrogen was 1.6 Pa, and a high frequency of 1000 V was applied to the plasma electrode and plasma treatment was performed for 12 seconds. A two-layer flexible substrate.

The initial peel strength of the obtained two-layer flexible substrate was 608 N/m, the number of pinholes for dry plating was 15098/m ² , and none of the pinholes having a diameter exceeding 30 μm, the amount of oligomers was 63%, and the number of concave defects It is 2017/m ² and has no concave defects with a diameter or maximum defect length exceeding 20 μm.

(Embodiment 18)

Example 18 was produced in the same manner as in Example 1 except that the mixing gas pressure of 25% by volume of argon-75 vol% nitrogen was 2.4 Pa, and a high frequency of 600 V was applied to the plasma electrode and plasma treatment was performed for 12 seconds. A two-layer flexible substrate.

The initial peel strength of the obtained two-layer flexible substrate was 614 N/m, the number of pinholes for dry plating was 19,713/m ² , and none of the pinholes having a diameter exceeding 30 μm, the amount of oligomers was 70%, and the number of concave defects It is 1798 pieces/m ² and has no concave defects with a diameter or a maximum defect length exceeding 20 μm.

(Comparative Example 12)

Although the mixing gas pressure of 25% by volume of argon-75 vol% nitrogen was 0.3 Pa, and the high frequency of 600 V was applied to the plasma electrode for 12 seconds, the discharge was unstable and could not be processed.

(Comparative Example 13)

Although the mixing pressure of 5% by volume of argon-75 vol% nitrogen is 4.7 Pa, and a high frequency of 600 V is applied to the plasma electrode for 12 seconds, the surface is wrinkled, resulting in subsequent characteristic evaluation being impossible. .

(Embodiment 19)

A two-layer flexible substrate of Example 19 was produced in the same manner as in Example 1 except that the argon gas pressure was 1.6 Pa, and a high frequency of 600 V was applied to the plasma electrode to carry out a plasma treatment for 12 seconds.

The initial peel strength of the obtained two-layer flexible substrate was 598 N/m, the number of pinholes for dry plating was 25673/m ² , and none of the pinholes having a diameter exceeding 30 μm, the amount of oligomers was 56%, and the number of concave defects It is 1897 pieces/m ² and has no concave defects with a diameter or a maximum defect length exceeding 20 μm.

(Embodiment 20)

Example 20 was produced in the same manner as in Example 1 except that the mixing gas pressure of 75 vol% argon-25 vol% nitrogen was 1.6 Pa, and the plasma electrode was subjected to a high frequency of 600 V for 12 seconds. A two-layer flexible substrate.

The initial peel strength of the obtained two-layer flexible substrate was 587 N/m, the number of pinholes for dry plating was 19,476 / m ² , and none of the pinholes having a diameter exceeding 30 μm, the amount of oligomers was 66%, and the number of concave defects It has 1674 pieces/m ² and has no concave defects with a diameter or a maximum defect length exceeding 20 μm.

(Example 21)

Example 21 was produced in the same manner as in Example 1 except that the mixing gas pressure of 50 vol% argon-50 vol% nitrogen was 1.6 Pa, and the plasma electrode was subjected to a high frequency of 600 V for 12 seconds. A two-layer flexible substrate.

The initial peel strength of the obtained two-layer flexible substrate was 569 N/m, the number of pinholes for dry plating was 24,384 / m ² , and none of the pinholes having a diameter exceeding 30 μm, the amount of oligomers was 62%, and the number of concave defects It is 1720 / m ² and has no concave defects with a diameter or maximum defect length exceeding 20 μm.

(Example 22)

A two-layer flexible substrate of Example 22 was produced in the same manner as in Example 1 except that a nitrogen gas pressure of 1.6 Pa was applied, and a high frequency of 600 V was applied to the plasma electrode to carry out a plasma treatment for 12 seconds.

The initial peel strength of the obtained two-layer flexible substrate was 601 N/m, the number of pinholes for dry plating was 27,846 / m ² , and none of the pinholes having a diameter exceeding 30 μm, the amount of oligomers was 59%, and the number of concave defects It is 2008/m ² and has no concave defects with a diameter or maximum defect length exceeding 20 μm.

The results of the above examples and comparative examples are shown in Table 1.

It is understood from Table 1 that by performing the surface treatment of the insulator film on the plasma treatment according to the conditions specified in the present invention, the amount of the oligomer of the insulator film can be made 70% or less of the amount of the oligomer before the surface treatment, and The number of pinholes of the dry plating is suppressed to 45,000 pieces/m ² or less, and the number of concave defects of the copper wet plating layer can be suppressed to 2,200 / m ² or less.

Further, when the environmental pressure of the surface-treated plasma treatment was less than 0.8 Pa, it was confirmed that the discharge was unstable, and the surface treatment of the insulator film could not be performed. Further, it has been found that if the applied voltage of the plasma electrode is too high, wrinkles of the insulator film occur, and it is impossible to manufacture a two-layer flexible substrate.

Claims (16)

A two-layer flexible substrate is formed on at least one side of an insulator film, and a bottom metal layer is formed by dry plating without passing through an adhesive, and copper is formed by dry plating on the underlying metal layer. In the film layer, the insulator film is subjected to a surface treatment on at least one of the surfaces, and the amount of the oligomer after the surface treatment is applied to only one of the insulating film is 70% or less of the amount of the oligomer before the surface treatment. The copper thin film layer is provided on the insulating film having a surface amount of oligomers of 70% or less, having a thickness of 50 nm to 500 nm, and having no pinholes having a diameter exceeding 30 μm, and pinholes having a diameter of 5 μm or more and 30 μm or less. It is 45,000 or less per 1 square meter. A two-layer flexible substrate according to claim 1, wherein the copper wet plating layer is formed on the copper thin film layer by wet plating. The two-layer flexible substrate of claim 2, wherein the copper wet plating layer has a thickness of 0.5 μm to 12 μm, and has no concave defects having a diameter or a maximum defect length exceeding 20 μm, and the diameter or the maximum The concave defect having a defect length of 10 μm or more and 20 μm or less is 2,200 or less per 1 square meter. The two-layer flexible substrate according to claim 1 or 2, wherein the underlying metal layer has a layer thickness of 5 nm to 50 nm and contains 6% by weight to 22% by weight of an additive element mainly composed of chromium. a nickel-chromium alloy composed of nickel, and a copper film provided on the underlying metal layer. The layer thickness of the conductor layer (copper layer) formed of the layer and the copper wet plating layer is 50 nm to 12 μm. The two-layer flexible substrate according to claim 1 or 2, wherein the insulator film is a polyimide film, a polyamide film, a polyester film, a polytetrafluoroethylene film, or a poly A resin film selected from the group consisting of a phenylene sulfide film, a polyethylene naphthalate film, and a liquid crystal polymer film. The two-layer flexible substrate according to claim 1 or 2, wherein the surface treatment is performed by using a DC voltage of 1500 V to 3000 V on the surface of the insulator film under an inert atmosphere of a pressure of 0.8 Pa to 4.0 Pa. Slurry discharge treatment. The two-layer flexible substrate according to claim 6, wherein the surface-treated inert environment is a nitrogen atmosphere, and the PCT peel strength after the surface treatment is 70% or more of the initial peel strength. The two-layer flexible substrate according to claim 1 or 2, wherein the surface treatment is performed by using a high-frequency voltage of 800 V to 2000 V on the surface of the insulator film under an inert atmosphere of a pressure of 0.8 Pa to 4.0 Pa. Plasma discharge treatment. A two-layer flexible substrate according to claim 8, wherein the surface-treated inert environment is a nitrogen atmosphere, and the PCT peel strength after the surface treatment is 70% or more of the initial peel strength. A method for producing a two-layer flexible substrate is formed on at least one surface of an insulator film by dry plating without passing through an adhesive a bottom metal layer, and a pinhole having a thickness of 50 nm to 500 nm and having a diameter of more than 30 μm is formed by dry plating on the underlying metal layer, and a pinhole system having a diameter of 5 μm or more and 30 μm or less is 45,000 per square meter. The following copper film layer is characterized in that the surface of the insulator film is subjected to a plasma of 2 to 100 seconds between the paired discharge electrodes of the plasma electrode under an inert atmosphere of a pressure of 0.8 Pa to 4.0 Pa. After the surface treatment of the discharge and the amount of the oligomer on the surface is 70% or less, an underlying metal layer is formed. The method for producing a two-layer flexible substrate according to claim 10, wherein the surface treatment by the plasma discharge applies a direct current voltage of 1500 V to 3000 V between the discharge electrodes of the plasma electrode. A method of producing a two-layer flexible substrate according to claim 10, wherein the surface treatment by the plasma discharge applies a high-frequency voltage of 800 V to 2000 V between discharge electrodes of the plasma electrode. A method for producing a two-layer flexible substrate, which is a method for producing a two-layer flexible substrate according to claim 7 of the invention, which is characterized in that at least one surface of the insulating film is used, and dry plating is used without passing through an adhesive. Forming the underlying metal layer and forming a copper thin film layer by dry plating on the underlying metal layer, wherein the surface of the insulating film is subjected to a nitrogen atmosphere at a pressure of 0.8 Pa to 4.0 Pa. The surface of the plasma generated by applying a 1500V~3000V DC voltage between the paired discharge electrodes of the plasma electrode for 2 to 100 seconds After the treatment, an underlying metal layer is formed. A method for producing a two-layer flexible substrate, which is a method for producing a two-layer flexible substrate according to claim 9 of the invention, which is characterized in that at least one surface of the insulating film is used, and dry plating is used without passing through an adhesive. Forming the underlying metal layer and forming a copper thin film layer by dry plating on the underlying metal layer, wherein the surface of the insulating film is subjected to a nitrogen atmosphere at a pressure of 0.8 Pa to 4.0 Pa. After the surface treatment of the plasma generated by applying a high-frequency voltage of 800V to 2000V for 2 to 100 seconds between the paired discharge electrodes of the plasma electrode, an underlying metal layer is formed. The method for producing a two-layer flexible substrate according to any one of claims 10 to 12, wherein the dry plating method is any one of a vacuum vapor deposition method, a sputtering method, and an ion plating method. By. The method for producing a two-layer flexible substrate according to any one of claims 10 to 12, wherein the insulator film is a polyimide film, a polyamide film, a polyester film, or a poly A resin film selected from the group consisting of a tetrafluoroethylene film, a polyphenylene sulfide film, a polyethylene naphthalate film, and a liquid crystal polymer film.