JP4588621B2 - Laminated body for flexible printed wiring board and Cu alloy sputtering target used for forming copper alloy layer of the laminated body - Google Patents

Description

  The present invention is a material for a flexible printed wiring board, and has a two-layer structure type flexible printed wiring board laminate formed by forming a conductor layer on a resin film (base film) without using an adhesive, and the laminate The present invention relates to a Cu alloy sputtering target used for forming a body copper alloy layer.

  In recent years, flexible printed wiring boards (flexible electronic circuit boards) that can be bent have been widely used in mobile phones, digital cameras, liquid crystal displays, and the like. Resin films (plastic films) are used for flexible printed wiring boards. Among them, polyimide films have excellent heat resistance and chemical stability, and are particularly excellent in mechanical properties. Since it is not damaged, it is used as a base film which is an electrically insulating substrate of a flexible printed wiring board which is rich in flexibility.

  The flexible printed wiring board is a laminated body for a flexible printed wiring board by forming a conductor layer on a resin film (base film) as typified by the polyimide film, and the conductor layer of the laminated body is electronically etched or the like. A circuit is formed. Here, in the laminated body in which the copper foil is provided as the conductor layer, since the adhesion between the resin film including the polyimide film and the copper foil is generally poor, the resin film and the copper foil may be joined with an adhesive. It has been broken. Moreover, the adhesive force between the resin film and the copper foil is ensured by applying a thermosetting or ultraviolet curable resin material on the copper foil having irregularities on the surface and then curing it. Yes.

  Now, with the progress of higher density electronic circuits, flexible printed wiring boards have been required to be finely processed. In this case, there arises a problem that non-uniform etching occurs due to unmelted adhesive in the etching process and unevenness of the copper foil. Moreover, when the thickness of the copper foil to join is thick, there exists a problem that it is difficult to produce the fine wiring of the space | interval narrower than a film thickness by an etching.

  As a method for solving these problems, the metallizing method has attracted attention. In the metalizing method, a copper seed layer is formed on a smooth resin film by vapor deposition or sputtering, and then a copper plating layer (copper plating film) having an appropriate thickness is formed thereon by electroplating. . This metallizing method is suitable for fine wiring formation because the thickness of the copper plating layer can be arbitrarily adjusted and a thin copper plating layer can be formed. Further, if a resin surface having a smooth surface is used as the substrate, the etching non-uniformity can be reduced.

  However, even with the metalizing method, since the adhesion between the copper layer and the resin film is not high, there is a problem in that peeling of the copper layer and the resin film (polyimide film) is likely to occur when an electronic circuit is mounted.

  In order to solve this problem, it has been proposed to form an adhesion layer between the copper layer and the resin film. For example, in Japanese Patent Publication No. 4-65558 (Patent Document 1), as a circuit material, an adhesive layer (adhesion layer) made of chromium / chromium oxide is formed on an electrically insulating support film, and a copper layer is formed thereon. Circuit materials designed to be formed have been proposed. In Japanese Patent Publication No. 57-18357 (Patent Document 2), a film of Ni, Co, Zr, Pd or an alloy containing these is formed as an adhesion layer on a plastic substrate, and a copper thin film is formed thereon. In Japanese Patent Publication No. 57-18356 (Patent Document 3), a Ni or Ni alloy film is formed as an adhesion layer on a polyimide film, and a copper film is formed thereon. A printed circuit board has been proposed.

  In JP-A-8-332697 (Patent Document 4), an alloy layer containing at least two of Ti, Co, Mo and Ni is formed as an adhesion layer on a plastic film, and a copper layer is formed thereon. A formed metal polymer film has been proposed. In JP 2001-77493 A (Patent Document 5), a tantalum carbide layer, a titanium carbide layer or an amorphous carbon layer is formed as an adhesion layer on a polyimide film, and a metal layer (copper layer) is formed thereon as a conductor layer. A flexible printed circuit board formed by forming a layer) has been proposed.

  Thus, in order to ensure the adhesiveness between the copper layer and the resin film, at present, those having an adhesive layer (seed layer) between the copper layer and the resin film have become mainstream. This prevents the copper layer from peeling off.

  However, in the case of having an adhesion layer made of a metal or alloy as described above, the etching characteristics of the copper layer and the etching characteristics of the adhesion layer are considerably different, and thus special etching is required. For example, in the case of having an adhesion layer made of Cr, the adhesion between the resin film and the copper layer is enhanced through the Cr adhesion layer, but on the other hand, etching of the Cr adhesion layer itself is difficult. Therefore, an adhesion layer made of a nickel chromium alloy has been proposed to solve this problem. In the case of an adhesion layer made of nickel-chromium alloy, which is currently the mainstream, it is possible to perform etching with the same ferric chloride solution that etches the copper layer, but the etching rate is different from the etching rate of the copper layer. Due to the difference in speed, non-uniform etching and residue are likely to occur.

  In addition, in the case of having an adhesion layer made of a metal or an alloy as described above, the etching characteristics in the vicinity of the interface due to the generation of an electrical contact potential at the junction between the copper layer and an adhesion layer made of a different metal. Changes significantly, and an adhesion layer with a width of several microns in contact with the copper layer remains as a portion that cannot be etched. These undissolved residues did not pose a problem when the wiring pitch is wide, but cannot be overlooked when the wiring pitch is about 20 μm or less.

  In this way, as electronic circuits become more dense (miniaturized) in the future, etching itself becomes a more difficult process than ever, making it difficult to perform two-stage etching that requires delicate control, Residue is a problem, and a slight undissolved portion of the adhesion layer around the copper layer becomes a serious problem that leads to a short circuit of the wiring.

  Therefore, there is a demand for a laminate for a flexible printed wiring board that has good adhesion between a resin film and a conductor layer, is easy to etch when providing an electronic circuit, and has few etching residues. Yes.

  Now, as the density of electronic circuits increases (miniaturization), a short circuit between wirings is emerging as a new problem. Copper tends to cause ion migration following silver, that is, metal diffusion in the presence of a small amount of moisture, and this ion migration (insulation deterioration) becomes a problem when the wiring interval is narrowed. That is, until now, it was not a big problem because the wiring interval was wide and the film surface was uneven, but it was serious under narrow wiring and when the film surface was smooth. It comes up as a problem.

  In order to suppress the ion migration of the wiring formed by etching the conductor layer such as the copper layer, it is necessary to improve the ion migration resistance of the wiring material (conductor layer) itself, and between the conductor layer and the resin film. It is necessary to improve adhesion. That is, if there is peeling between the conductor layer and the resin film, moisture stays in that portion for a long time, and ion migration is rapidly promoted. Therefore, it is necessary that the conductor layer and the resin film are in close contact with each other. Further, it is necessary to reduce the etching residue between the wirings, and to reduce the slight undissolved residue due to the etching around the wirings. This is because a slight unmelted portion around the wiring has the same effect as that of further narrowing the wiring interval, and therefore promotes ion migration.

Therefore, in order to suppress ion migration, the adhesiveness between the resin film and the conductor layer is high, there is no generation of residues between the wirings in the process of forming the wirings on the conductive layer, and there is no undissolved residue around the wirings. It is important that the ion migration resistance of the conductor layer itself is high.
Japanese Patent Publication No. 4-65558 (pages 1 and 2, Fig. 1) Japanese Examined Patent Publication No.57-18357 (first page) Japanese Patent Publication No.57-18356 (pages 1 and 2) JP-A-8-332697 (pages 1 and 2, FIG. 1) JP 2001-77493 A (pages 1 and 2, FIG. 1)

Then, the subject of this invention is the flexible printed wiring board excellent in the etching property while being excellent in the adhesiveness of a resin film and a conductor layer in the laminated body for flexible printed wiring boards formed by forming a conductor layer on a resin film. Providing a laminate, providing a laminate for a flexible printed wiring board excellent in adhesion, etching properties and ion migration resistance, and forming a conductor layer of the laminate for a flexible printed wiring board It is providing the Cu alloy sputtering target used for this.

  In order to solve the above problems, the present invention takes the following technical means.

In the invention of claim 1, a copper alloy layer containing a total of 0.01 to 5.0 atomic% of one or more of Cr, Ta, W, V, Y, Co and Nd is formed on the resin film. It is a laminated body for flexible printed wiring boards characterized by being formed.

According to a second aspect of the invention, on a resin film, Cr, Ta, W, V, Y, and 0.01 to 5.0 containing atomic% in total of one to three kinds of Co and Nd, and, Ti A laminate for a flexible printed wiring board characterized by forming a copper alloy layer containing 0.01 to 8.0 atomic% of one or two of Ni, Si, Mg and Al in total is there.

According to a third aspect of the present invention, a copper alloy layer containing one or more of Cr, Ta, W, V, Y, Co, and Nd in a total amount of 0.01 to 5.0 atomic% is formed on a resin film. A laminate for a flexible printed wiring board, comprising a copper sputter layer and / or a copper plating layer formed on the copper alloy layer.

The invention according to claim 4, on a resin film, Cr, Ta, W, V, Y, and 0.01 to 5.0 containing atomic% in total of one to three kinds of Co and Nd, and, Ti A copper alloy layer containing 0.01 to 8.0 atomic% of one or two of Ni, Si, Mg and Al in total is formed, and a copper sputter layer and / or copper plating is formed on the copper alloy layer A layered product for a flexible printed wiring board, comprising a layer. A fifth aspect of the present invention is a sputtering target for forming the copper alloy layer according to the first or third aspect, wherein one or more of Cr, Ta, W, V, Y, Co, and Nd are combined. A Cu alloy sputtering target comprising a Cu alloy containing 0.01 to 5.0 atomic%. Invention of Claim 6 is a sputtering target for forming the copper alloy layer of Claim 2, 4, Comprising: 1 type-3 types are selected from Cr, Ta, W, V, Y, Co, and Nd. A Cu alloy containing 0.01 to 5.0 atomic% in total and containing one or two of Ti, Ni, Si, Mg and Al in a total of 0.01 to 8.0 atomic% This is a Cu alloy sputtering target.

According to invention of Claim 1 or Claim 3, in the laminated body for flexible printed wiring boards of the 2 layer structure type formed by forming a conductor layer on a resin film without using an adhesive agent, a resin film, a conductor layer, It is possible to provide a laminate for a flexible printed wiring board that is excellent in adhesiveness, and that is excellent in etching property and can sufficiently cope with high density of electronic circuits. Further, according to the invention of claim 2 or claim 4, in a laminate for a flexible printed wiring board of a two-layer structure type in which a conductor layer is formed on a resin film without using an adhesive, adhesion, etching It is possible to provide a laminate for a flexible printed wiring board that is excellent in the resistance and ion migration resistance and can sufficiently cope with the high density of electronic circuits. Moreover, according to the invention of Claim 5, the Cu alloy sputtering target for forming the copper alloy layer of the laminated body for flexible printed wiring boards of Claims 1 and 3 can be provided. Moreover, according to invention of Claim 6, the Cu alloy sputtering target for forming the copper alloy layer of the laminated body for flexible printed wiring boards of Claim 2, 4 can be provided.

  Hereinafter, the present invention will be described in detail.

  The first laminate for a flexible printed wiring board according to the present invention comprises a resin film as a base film, for example, a polyimide film as a representative thereof, and Cr, Ta, W, V, Y, Co, and Nd as conductor layers. The copper alloy layer (A) which contains 1 or more types among these, and the remainder consists of Cu and an unavoidable impurity is formed.

  The present inventor has investigated in detail the relationship between the type and amount of additive elements constituting the copper alloy layer and the adhesion between the copper alloy layer and the polyimide film, and using an aqueous ferric chloride solution. The state of residue generation near the wiring side in the etching process of the copper alloy layer was investigated in detail. As a result, on the polyimide film, the additive element contains one or more of Cr, Ta, W, V, Y, Co and Nd in a total of 0.01 to 10.0 atomic%, with the remainder being Cu and inevitable. By forming the copper alloy layer (A) made of impurities, the adhesive strength between the copper alloy layer (A) and the polyimide film is as high as that provided by the adhesion layer made of Cr. I was able to. In this case, it is considered that the d-electron of the transition metal such as the additive element moves to the oxygen of the polyimide film, thereby increasing the adhesion.

  Further, when an electronic circuit is provided on the copper alloy layer (A), etching can be performed without generating an etching residue in an insulating portion between the wirings by using the same ferric chloride aqueous solution as that for etching copper. In addition, unlike the conventional method of forming the adhesion layer, there is no dissimilar metal, so that no undissolved residue that remains without being removed near the side surface of the wiring does not occur.

About the reason for prescribing the copper alloy layer (A) to contain at least one of Cr, Ta, W, V, Y, Co and Nd as additive elements in a total amount of 0.01 to 5.0 atomic% explain. A copper alloy layer (A) having a thickness of 2 μm was formed on the polyimide film by a sputtering method, and the adhesion strength (peel strength) was measured by a peel test method. As a result, when the total content of the additive elements was less than 0.01 atomic%, the effect of improving adhesion was not obtained, and the peel strength was 100 N / m or less. And the adhesive strength improved when the total content of the additive elements was 0.01 atomic% or more, and the peel strength improved to 300 N / m when the total content was 0.1 atomic% or more. The peel strength is 400 N / m or more in the range of 0.15 to 7 atomic%, and the peel strength is 450 N / m in the range of 0.2 to 5 atomic%, and 500 N in the range of 0.3 to 4 atomic%. / M. And peel strength fell, without improving, even if the total content of the said additional element exceeded 10 atomic%, and became 300 N / m. Further, when the total content of the additive elements was 20 atomic% or more, the peel strength was improved again, but etching residues were generated. In the present invention, the total content of the additive elements is in the range of 0.01 to 5.0 atomic% as a range in which the adhesion can be improved while suppressing the generation of etching residues. In addition, from the point which suppresses generation | occurrence | production of an etching residue more preferably, the range of 0.1-1.5 atomic% is good.

  The thickness of the copper alloy layer (A) is preferably in the range of 10 nm to 10 μm. When the thickness of the copper alloy layer (A) is less than 10 nm, when a copper layer is further formed on the copper alloy layer (A), a pinhole is formed in the copper alloy layer (A), whereas it exceeds 10 μm. This is because the resin film warps due to stress and is not good.

In addition, the second laminate for a flexible printed wiring board according to the present invention includes a resin film as a base film, for example, a polyimide film as a representative thereof, and Cr, Ta, W, V, Y, Co as conductor layers. 1 to 3 in total and 0.01 to 5.0 atomic percent of Nd, and one or two of Ti, Ni, Si, Mg and Al in total 0.01 to 8 A copper alloy layer (B) containing 0.0 atomic% and the balance being made of Cu and inevitable impurities is formed.

That is, as described above, excellent adhesion and etching can be obtained by containing 0.01 to 5.0 atomic% of 1 to 3 kinds of Cr, Ta, W, V, Y, Co and Nd in total. In addition to obtaining properties, the copper alloy layer (B) containing 0.01 to 8.0 atomic% in total of one or two of Ti, Ni, Si, Mg and Al, Ion migration of the wiring formed in the copper alloy layer (B) can be suppressed. Ti, Ni, Si, Mg, and Al are elements that form a thin oxide film on the copper surface. This oxide film has an effect of suppressing elution of Cu, and the ion migration resistance of the copper alloy layer (B) itself is reduced. This is because it can be increased.

In this case, the reason why the total content of one or two of Ti, Ni, Si, Mg and Al is specified to be 0.01 to 8.0 atomic% is that the ion migration resistance is less than 0.01 atomic%. This is because the improvement effect cannot be obtained, and the more effective the ion migration resistance is, the more effective is 0.1 atomic% or more. On the other hand, when it exceeds 8.0 atomic%, the adhesive force starts to decrease. . In addition, when 1 to 3 types of Cr, Ta, W, V, Y, Co, and Nd are not contained in a total of 0.01 to 5.0 atomic%, the original adhesive strength is low. Fine separation occurs in a high-temperature and high-humidity atmosphere, and ion migration occurs from that point.

And the appropriate range in the case of single addition changes with addition elements, and is 0.1-7.0 atomic% in Ti, Since especially Ti also improves adhesiveness by addition with Cr, 0.1% ˜4.0 atomic% is a more preferable range. On the other hand, with respect to Ni, Si, Mg, and Al, the adhesiveness decreases when the content is large, so 0.05 to 2.0 atomic% is an appropriate range. Overall, for Cr, Ta, W, V, Y, Co, and Nd, Cr: 0.3 to 5.0 atomic%, more preferably 0.3 to 3.0 atomic%, Ta, W, V, Y, Co and Nd: The range of 0.2 to 5.0 atomic% is good. For Ti, Ni, Si, Mg and Al, Ti: 0.1 to 4.0 atomic%, Ni and The range of Si: 0.1-7.0 atomic% and Mg and Al: 0.1-1.0 atomic% are good. The combined use (simultaneous addition) of Cr and Ti is the most effective.

  Further, the thickness of the copper alloy layer (B) is preferably in the range of 10 nm to 10 μm for the same reason as the copper alloy layer (A). When the thickness of the copper alloy layer (B) is less than 10 nm, when a copper layer is further formed on the copper alloy layer (B), a pinhole is formed in the copper alloy layer (B), whereas when the thickness exceeds 10 μm. This is because the resin film is warped by stress and is not good.

The 3rd laminated body for flexible printed wiring boards concerning this invention is 1 type in Cr, Ta, W, V, Y, Co, and Nd on the resin film which is a base film, for example, the polyimide film which is the representative. The copper alloy layer (A) containing 0.01 to 5.0 atomic% in total is formed, and a copper sputter layer and / or a copper plating layer is formed on the copper alloy layer (A). It is.

  Thus, even if it is set as the structure which formed the copper alloy layer (A) on the resin film, and also formed the copper sputter layer and / or the copper plating layer on it, the said 1st laminated body for flexible printed wiring boards Similarly, a laminate for a flexible printed wiring board having excellent adhesion and etching properties can be obtained. Adhesion is a problem at the joint between the resin film and the conductor layer. In this case, the copper alloy layer (A) is formed on the resin film, and the etching characteristics of the copper alloy layer (A) Since there is almost no difference from the etching characteristics of the copper sputter layer or the copper plating layer, even if the copper sputter layer and / or the copper plating layer is further formed on the copper alloy layer (A), the adhesion In addition, the etching property is excellent.

  In this case, the copper sputter layer is generally formed as a seed layer for enabling high-speed electroplating when a copper plating layer is formed on the copper sputter layer, and is formed by a sputtering method. Made of pure copper having a purity of about 99.9%. And the thickness of this copper sputter layer has the good range of 50 nm-20 micrometers. If the copper sputter layer has a thickness of less than 50 nm, when a copper plating layer is further formed on the copper sputter layer, pinholes are formed in the copper plating layer. On the other hand, if the thickness exceeds 20 μm, the resin film as the base film is stressed. This is because it is not good. The sputtered copper layer also serves to improve the adhesion between the copper alloy layer and the copper plating layer. That is, when copper plating is directly performed on the copper alloy layer, the adhesion between the copper alloy layer and the copper plating layer may be low. Such a problem can be solved by interposing a copper sputter layer between the copper alloy layer and the copper plating layer.

  The copper plating layer is formed by electroplating to increase the thickness of the conductor layer including the copper alloy layer (A) when it is required to allow more current to flow through the electronic circuit. It is what is done. And the thickness of this copper plating layer has the good range of 1-20 micrometers. If the thickness of the copper plating layer is less than 1 μm, the current that can be passed through the electronic circuit is not sufficient, whereas if it exceeds 20 μm, the resin film is warped by stress, which is not good.

The 4th laminated body for flexible printed wiring boards concerning this invention is 1 type in Cr, Ta, W, V, Y, Co, and Nd on the resin film which is a base film, for example, the polyimide film which is the representative. ~ 3 kinds are contained in a total of 0.01 to 5.0 atomic%, and one kind or two kinds of Ti, Ni, Si, Mg and Al are contained in a total of 0.01 to 8.0 atomic%. The copper alloy layer (B) is formed, and a copper sputter layer and / or a copper plating layer is formed on the copper alloy layer (B).

  Thus, even if it is set as the structure which formed the copper alloy layer (B) on the resin film, and also formed the copper sputtered layer and / or the copper plating layer on it, the said 2nd laminated body for flexible printed wiring boards Similarly, a laminate for a flexible printed wiring board having excellent adhesion and etching properties and excellent ion migration resistance can be obtained. Adhesion is a problem at the joint between the resin film and the conductor layer. In this case, the copper alloy layer (B) is formed on the resin film, and the etching characteristics of the copper alloy layer (B) Since there is almost no difference from the etching characteristics of the copper sputter layer or the copper plating layer, even if the copper sputter layer and / or the copper plating layer is further formed on the copper alloy layer (B), the adhesion In addition, it is excellent in etching property and ion migration resistance.

  And like the said 3rd laminated body for flexible printed wiring boards, the thickness of a copper sputter layer has the good range of 50 nm-20 micrometers, and the thickness of a copper plating layer has the good range of 1-20 micrometers.

A polyimide film with a thickness of 25 μm (trade name Kapton (registered trademark of DuPont)) manufactured by Toray DuPont Co., Ltd. was used as the base film. A 2 μm thick copper alloy layer having a composition of 2 is formed by sputtering with Ar gas using a copper alloy target having a predetermined composition, and this is then subjected to conditions of 250 ° C. × 30 minutes in a vacuum heat treatment furnace After heat treatment, sample no. The laminated body for flexible printed wiring boards of Example 2 was obtained. The heat treatment is for diffusing Cr, which is an additive element of the copper alloy layer, to promote bonding with oxygen in the polyimide film. The sputtering conditions were Ar gas pressure: 2 mTorr (0.27 Pa) and supply power: 10 W / cm ² .

Similarly, a copper alloy layer (Example: Sample Nos. 3 to 8 , Sample Nos. 12 to 14, 16, and 17, Reference Example: Sample Nos. 9 and 15 ) having the composition shown in Table 1 is formed. Each flexible printed wiring board laminate and a flexible printed wiring board laminate obtained by forming a metal layer having a thickness of 2 μm (comparative example: Sample Nos. 1, 10, and 11) were obtained. In addition, for sputtering, a copper alloy target having a predetermined composition, or a metal chip with an appropriate amount of metal chips arranged on the copper alloy target was used.

  These obtained sample Nos. 1-No. For each of the laminates for flexible printed wiring board No. 17, a copper alloy layer (however, sample No. 1: Cu layer, sample No. 11: Cr layer) is 10 mm wide by using a ferric chloride aqueous solution by wet etching. , Etching was carried out into a 90 mm long stripe. And the etching edge part and film surface of the copper alloy layer in which the stripe was formed were observed with SEM (scanning electron microscope), and the presence or absence of the etching residue was investigated. The results are shown in Table 1.

  Sample No. 1-No. For each of the 17 flexible printed wiring board laminates, peel strength was measured according to the peel test method of JIS 6481. The results are shown in Table 1.

As shown in Table 1, sample No. 1 satisfying the requirements of the present invention. 2-8 and sample No. In the examples of 12 to 14, 16, and 17, the adhesiveness to the polyimide film was excellent, and the etching property with no etching residue was excellent. In contrast, sample no. In Comparative Example 1, the peel strength was as low as 60 N / m and the adhesion was poor because it was not a copper alloy layer defined in the present invention but a simple Cu layer. Sample No. In Comparative Example 10, the etching residue was generated because the Cr content of the copper alloy layer deviated from the upper limit defined in the present invention. Sample No. In Comparative Example 11, since it was a metal layer made of Cr instead of the copper alloy layer defined in the present invention, etching with an aqueous ferric chloride solution could not be performed.

A polyimide film with a thickness of 25 μm (trade name Kapton (registered trademark of DuPont)) manufactured by Toray DuPont Co., Ltd. was used. A copper alloy layer having a composition of 19 and a thickness of 1 μm was formed by sputtering with Ar gas using a copper alloy target having a predetermined composition. Next, a 1 μm thick copper sputtered layer made of Cu was formed thereon by sputtering. And this thing was heat-processed on the conditions for 250 degreeC x 30 minutes in the vacuum heat processing furnace. Next, a copper plating layer having a thickness of 6 μm was formed on the copper sputtered layer by Cu electroplating. The laminated body for flexible printed wiring boards of 19 Examples was obtained. The sputtering conditions were Ar gas pressure: 2 mTorr (0.27 Pa) and supply power: 10 W / cm ² .

  Similarly, a copper alloy layer having a composition shown in Table 2 (Example: Sample Nos. 20 to 23, Comparative Example: Sample No. 24), a 1 μm thick copper sputter layer, and a 6 μm thick copper plating layer are formed in this order. Each flexible printed wiring board laminate, a 1 μm thick Cu layer (Comparative Example: Sample No. 18), a 1 μm thick copper sputter layer, and a 6 μm thick copper plating layer are formed in this order. A laminate for a wiring board was obtained.

  These obtained sample Nos. 18-No. For each of the 24 flexible printed wiring board laminates, the conductor layer was etched into a stripe shape having a width of 10 mm and a length of 90 mm using a ferric chloride aqueous solution by a wet etching method. And the etching edge part and film surface of the conductor layer in which the stripe was formed were observed with SEM (scanning electron microscope), and the presence or absence of the etching residue was investigated. The results are shown in Table 2.

  Sample No. 18-No. For each of the 24 flexible printed wiring board laminates, peel strength was measured according to the peel test method of JIS 6481. The results are shown in Table 2.

Sample No. 18-No. For each of the 24 flexible printed wiring board laminates, the conductor layer was etched with a ferric chloride aqueous solution to form a comb wiring pattern (line / space = 300 μm / 300 μm) with a pitch of 300 μm. Then, 1 μL of ion-exchanged water is dropped between the wires, a DC voltage of 50 V is applied between the wires in a high-temperature and high-humidity atmosphere at 50 ° C. and 85 to 93 RH, and a 168-hour energization test is performed. The insulation resistance of was measured. The initial insulation resistance was in the range of 1 × 10 ¹⁰ to 1 × 10 ¹² Ω. Then, after 168 hours, when the insulation resistivity decreased to 50% of the initial insulation resistance, the ion migration resistance was evaluated by determining that the insulation was deteriorated. The results are shown in Table 2.

  As shown in Table 2, the sample No. 1 satisfying the requirements of the present invention. 19-No. In the example of 23, while being excellent in the adhesiveness with respect to a polyimide film, it was excellent in the etching property which does not produce an etching residue, and was excellent also in the ion migration resistance. In contrast, sample no. In 18 comparative examples, since it was not a copper alloy layer prescribed | regulated by this invention but a mere Cu layer, while peel strength was as low as 60 N / m and adhesiveness was inferior, ion migration resistance was disqualified. Sample No. In Comparative Example 24, the content of the additive element in the copper alloy layer deviated from the upper limit (8.0 atomic%) defined in the present invention, and therefore the peel strength was as low as 280 N / m.

Claims (6)

A copper alloy layer containing one or more of Cr, Ta, W, V, Y, Co, and Nd in a total amount of 0.01 to 5.0 atomic% is formed on the resin film. Laminated body for flexible printed wiring boards. On the resin film, one to three of Cr, Ta, W, V, Y, Co and Nd are contained in a total of 0.01 to 5.0 atomic%, and Ti, Ni, Si, Mg and A laminate for a flexible printed wiring board, comprising a copper alloy layer containing one or two of Al in a total amount of 0.01 to 8.0 atomic%. On the resin film, a copper alloy layer containing 0.01 to 5.0 atomic% in total of one or more of Cr, Ta, W, V, Y, Co, and Nd is formed, and the copper alloy layer is formed on the copper alloy layer. A laminate for a flexible printed wiring board, comprising a sputtered copper layer and / or a copper plated layer. On the resin film, one to three of Cr, Ta, W, V, Y, Co and Nd are contained in a total of 0.01 to 5.0 atomic%, and Ti, Ni, Si, Mg and A copper alloy layer containing a total of 0.01 to 8.0 atomic% of one or two of Al is formed, and a copper sputter layer and / or a copper plating layer is formed on the copper alloy layer. A laminate for a flexible printed wiring board. A sputtering target for forming the copper alloy layer according to claim 1, wherein at least one of Cr, Ta, W, V, Y, Co, and Nd is 0.01 to 5.0 in total. A Cu alloy sputtering target comprising a Cu alloy containing at%. 5. A sputtering target for forming the copper alloy layer according to claim 2, wherein one to three of Cr, Ta, W, V, Y, Co, and Nd are 0.01 to 5 in total. .0 contains atomic%, and, a Cu alloy, wherein Ti, Ni, Si, that consists of one or a Cu alloy containing 0.01 to 8.0 atomic% of two or a total of Mg and Al Sputtering target.