JP2015104896A - Copper polyimide laminated film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a copper polyimide laminated film in which peeling strength at normal condition and peeling strength after heat treatment are stably improved.SOLUTION: A copper polyimide laminated film is formed such that on a polyimide film, a seed layer 1 comprising alloy of nickel and chromium, a barrier layer, a seed layer 2 comprising alloy of nickel and chromium, and a copper layer are formed in this order by vacuum thin film method, and a copper layer is further put thereon by plating method.

Description

  The present invention relates to a copper polyimide laminated film that can be suitably used as a base material for electronic components such as flexible printed circuit boards, TAB tapes, and COF tapes. In particular, it has excellent adhesion to the substrate and adhesion after heat load, and even after forming a fine pattern lead wire corresponding to downsizing of electronic equipment, adhesion after heat load after electroless plating It is related with the copper polyimide laminated film which is excellent in the property, and can perform pattern formation with high reliability.

    Conventionally, a flexible printed wiring board having a three-layer structure in which a copper foil is bonded to a polyimide film via an adhesive layer is known. This three-layer structure type flexible printed wiring board is used because the heat resistance of the adhesive used is inferior to that of the base film, which may cause problems such as deformation and peeling during processing at high temperatures. Since the thickness of the copper foil is usually 10 μm or more, there is a drawback that patterning for high-density wiring with a narrow pitch is difficult.

    On the other hand, a flexible double-layer structure in which a copper layer is formed on a polyimide film by a dry plating method (for example, a vacuum deposition method, a sputtering method, an ion plating method, etc.) or a wet plating method without using an adhesive. A printed wiring board is also known. This two-layer structure type flexible printed wiring board is capable of high-density wiring because the copper layer can be made thinner than 10 μm, but the peel strength between the copper layer and the base film is insufficient. For this reason, when a pattern for high-density wiring is formed, there is a problem that the lead wire becomes thin and is easily peeled off from the base film. There is also a problem that the peel strength after the heat treatment is further reduced. In particular, if electroless plating such as tin, nickel, solder, or gold is performed after pattern formation and further heat treatment is performed, the peel strength between the lead wire and the substrate film is greatly reduced. It was.

    In order to solve these problems, a method of controlling the modified layer thickness of the polyimide film (Patent Document 1), and a method that specifies the surface roughness and the amount of nitrogen of the polyimide film surface have been proposed (Patent Document 2). ). However, even with such conventional techniques, the peel strength between the copper layer and the polyimide film may be insufficient, and the peel strength after heat treatment or the peel strength after heat treatment after electroless plating is performed. There were cases where the peel strength was insufficient.

    On the other hand, in order to improve the peeling strength after heat treatment, a method of forming an amorphous layer as an intermediate layer for providing a heat-resistant layer between a polymer substrate and a metal thin film as a conductive layer (Patent Document) 3) Further, a metal oxide layer is formed as an intermediate layer, the thickness is limited to 3 to 35 nm, the surface of the polyimide base material is plasma-treated, and the surface roughness is 0. By limiting to 5 nm or more and less than 5 nm, the peeling strength between the polyimide base material and the metal layer can be maintained at 1.0 kg / cm or more, and the decrease in the peeling strength after the heat treatment can be suppressed. A method that facilitates continuous production is also disclosed (Patent Document 4).

  In Patent Document 3, it is described that a sufficient peeling strength can be obtained by exposing the polyimide substrate to oxygen-containing plasma as a pretreatment and setting the surface roughness to 5 to 100 nm. However, in order to bring the surface roughness of the film into this range, plasma treatment for a long time is required, and the continuous treatment with high productivity has a large problem and is not satisfactory. Also in Patent Document 4, it is necessary to control the surface roughness within an appropriate range, and it is difficult to produce industrially stably.

JP 2003-334890 A JP 2008-78276 A JP-A-9-201900 JP-A-11-268183

    An object of the present invention is to stably improve the peel strength in a normal state and the peel strength after heat treatment, which was insufficient in such a conventional copper polyimide laminated film.

In order to solve the above object, the present invention has the following configuration.

In the first invention, a seed layer 1 made of an alloy of nickel and chromium, a barrier layer, a seed layer 2 made of an alloy of nickel and chromium, and a copper layer are formed on the polyimide film in this order by a vacuum thin film method, Furthermore, it is a copper polyimide laminated film in which a copper layer is laminated by plating.
The second invention is characterized in that the barrier layer is a metal oxide.
In a third aspect of the invention, the metal oxide is tin oxide, indium oxide, or indium tin oxide.
In the fourth invention, the seed layer 1, the barrier layer, and the seed layer 2 each have a thickness of 2 nm to 100 nm, and the peel strength T1 between the copper layer and the polyimide film in the normal state is the thickness of the copper layer. It is characterized by being 5.0 N / cm or more in terms of 8.5 μm.
In the fifth invention, the seed layer 1, the barrier layer, and the seed layer 2 have a film thickness of 2 nm to 100 nm, the peel strength T1 in a normal state, and the peel strength T2 after heat treatment at 150 ° C. for 168 hours. The ratio T2 / T1 is 0.6 or more.
In a sixth invention, the polyimide film comprises an aromatic tetracarboxylic acid anhydride comprising pyromellitic dianhydride and 3,3 ′, 4,4′-diphenyltetracarboxylic dianhydride, and 4,4 ′. -An aromatic diamine composed of diaminodiphenyl ether and paraphenylenediamine is a main component.

    According to the present invention, excellent adhesion to a substrate and adhesion after heat load, and even when a fine pattern lead corresponding to downsizing of electronic equipment is formed, after heat load after performing electroless plating It is possible to provide a copper-polyimide laminated film that is excellent in adhesiveness and can form a highly reliable pattern. Peeling strength in the wiring pattern is stable, there is little decrease in peeling strength due to thermal load when processing as a substrate for electronic equipment, and stability and yield of equipment using the copper polyimide laminated film of the present invention is reduced. Can be improved.

The present invention will be described below.

    As a polyimide film used in the present invention, an aromatic tetracarboxylic acid anhydride and an aromatic diamine are used as raw materials, and a polyamic acid obtained by polymerizing these in an organic solvent is cast into a film and imidized. In this process, a biaxially stretched polyimide film can be used.

  Aromatic tetracarboxylic acids are pyromellitic acid, 3,3 ′, 4,4′-biphenyltetracarboxylic acid, 2,3 ′, 3,4′-biphenyltetracarboxylic acid, 3,3 ′, 4,4 ′. Selected from benzophenone tetracarboxylic acid, 2,3,6,7-naphthalenedicarboxylic acid, 2,2-bis (3,4-dicarboxyphenyl) ether, pyridine-2,3,5,6-tetracarboxylic acid, etc. Aromatic diamines include paraphenylenediamine, metaphenylenediamine, benzidine, paraxylylenediamine, 4,4′-diaminodiphenyl ether, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylsulfone, 3,3′-dimethyl-4,4′-diaminodiphenylmethane, 1,5-diaminonaphthalene, 3,3′-dimethyl Kishibenchijin, selected from such as 1,4-bis (3-methyl-5-aminophenyl) benzene.

    Among these, the aromatic tetracarboxylic acid anhydride includes pyromellitic acid anhydride and 3,3 ′, 4,4′-biphenyltetracarboxylic acid anhydride, and the aromatic diamine includes paraphenylenediamine, 4 , 4′-diaminodiphenyl ether is preferably selected for stretchability and mechanical stability as a polyimide film.

    In order to produce a polyimide film from a polyamic acid solution, a polyamic acid solution to which a cyclization catalyst and a dehydrating agent are added is cast onto a support from a slit-shaped die, and is formed into a film, and imidization is performed on the support. It is preferable that after partially proceeding to form a self-supporting gel film, the gel film is peeled off from the support, heat-dried, and heat-treated.

    The gel film is heated to 30 to 200 ° C., preferably 40 to 150 ° C. by heat from the support and heat from a heat source such as hot air or an electric heater, and causes a ring-closing reaction to remove volatile components such as an organic solvent. It becomes self-supporting by drying and can be peeled from the support.

    The gel film peeled from the support is stretched in the longitudinal direction. The stretching is preferably carried out at a temperature of 140 ° C. or lower and a magnification of about 1.1 to 1.5 times.

  The gel film stretched in the longitudinal direction is introduced into a tenter device, gripped at both ends in the width direction by the clip, and stretched in the width direction while running with the tenter clip. The film dried in the drying zone is heated for 15 seconds to 10 minutes with hot air, an infrared heater or the like. Next, heat treatment is preferably performed at a temperature of 250 to 500 ° C. for 15 seconds to 20 minutes with hot air and / or an electric heater.

  In the copper polyimide laminated film of the present invention, a seed layer 1 made of an alloy of nickel and chromium, a barrier layer, a seed layer 2 made of an alloy of nickel and chromium, and a copper layer are formed on the polyimide film by a vacuum thin film method. It is formed in order, and a copper layer is further laminated thereon by a plating method.

  It is estimated that the cause of the decrease in the peel strength after heat treatment in the wiring pattern is that the copper atoms diffuse and reach the polyimide film, and the polyimide is thermally deteriorated. For this reason, the diffusion of copper can be prevented by providing the barrier layer of the present invention, and the heat resistance is improved. Further, by providing the seed layer 1 of the present invention, the peel strength between the barrier layer and the polyimide film can be improved. Furthermore, by providing the seed layer 2 of the present invention, the peel strength between the barrier layer and the copper layer can be improved. By adopting the three-layer structure of the present invention, both the normal peel strength and the peel strength after heat treatment can be improved, and a highly reliable copper polyimide laminated film can be produced.

  As a method of forming the seed layer 1 made of an alloy of nickel and chromium on the polyimide film, it can be formed by a vacuum thin film method such as a vacuum deposition method, an ion plating method, a sputtering method, a CVD method, or an ion cluster beam method. Among these, it is preferable to form by the sputtering method using the target of the weight ratio of the target nickel and chromium. The weight ratio of nickel in the seed layer is preferably 70 to 96 wt%, and the ratio of chromium corresponding to this is preferably 30 to 4 wt%. When the weight ratio of nickel is less than 70 wt%, it becomes difficult to remove the seed layer when forming a wiring pattern on the copper polyimide laminated film by etching, and when the weight ratio of nickel exceeds 96 wt%, the target during sputtering When magnetron sputtering is industrially effective, the magnetic field required for magnetron discharge cannot be obtained on the target surface, and the sputtering process itself tends to be difficult.

  The thickness of the seed layer 1 made of an alloy of nickel and chromium is preferably 2 nm or more and 100 nm or less. If it is less than 2 nm, the peel strength after thermal load may be insufficient, and if it is 100 nm or more, it is difficult to remove the seed layer when forming a wiring pattern by an etching method. More preferably, they are 3 nm or more and 50 nm or less, More preferably, they are 5 nm or more and 30 nm or less.

  Before forming the seed layer 1 by the vacuum thin film method, the polyimide film surface may be surface-treated. For example, there are corona treatment, plasma treatment, ultraviolet treatment, flame treatment and the like. Among these, plasma processing is preferably used. The plasma treatment may be performed in a separate vacuum tank before the seed layer 1 is formed in advance by a vacuum thin film method, or may be performed immediately before the seed layer 1 is formed in the same vacuum tank. As the plasma generating power source, it is preferable to use a direct current or an AC power source of 20 to 100 MHz. In order to generate plasma, gases such as oxygen, nitrogen, argon and carbon dioxide can be used.

  A barrier layer is laminated on the seed layer 1 made of an alloy of nickel and chromium formed by the vacuum thin film method. As the barrier layer, metal compounds such as metal oxides, metal nitrides, metal sulfides, and mixtures thereof can be used. The barrier layer can be formed by a vacuum thin film method such as a vacuum deposition method, an ion plating method, a sputtering method, a CVD method, or an ion cluster beam method.

Examples of the metal oxide include aluminum oxide, tin oxide, zinc oxide, indium oxide, indium tin oxide, magnesium oxide, chromium oxide, nickel oxide, iron oxide, silicon oxide, and iridium oxide. Examples of the metal nitride include boron nitride, silicon nitride, titanium nitride, copper nitride, aluminum nitride, zinc nitride, chromium nitride, vanadium nitride, indium nitride, thallium nitride, lithium nitride nitride, and gallium nitride. Examples of the metal sulfide include zinc sulfide, iron sulfide, and molybdenum disulfide.
The main application of the present invention is to be used as a substrate for a circuit, and considering that it can be easily etched with a ferric chloride solution in an etching process, an oxide mainly composed of indium is most preferable. As the oxide mainly composed of indium, an oxide containing 50% by weight or more of indium oxide is preferable. More specifically, it is an oxide mainly composed of indium and tin known as indium tin oxide. The ratio of indium and tin in the indium tin oxide can be selected arbitrarily, but considering the etching properties when producing a circuit pattern using a ferric chloride solution, the content of tin converted to tin oxide Is preferably selected in the range of 0 to 50% by weight. If tin exceeds 50% by weight, etching becomes difficult, which is not preferable. Further, other elements and oxides may be added to the extent that the characteristics of the oxide mainly composed of indium are not impaired.

  A method for manufacturing an indium tin oxide film as a barrier layer will be described. The barrier layer made of indium tin oxide can be formed by a vacuum thin film method such as a vacuum deposition method, an ion plating method, a sputtering method, a CVD method, or an ion cluster beam method. Among these, it is preferable to form by the sputtering method using the target of the target weight ratio of indium and tin. The thickness of the barrier layer is preferably 2 nm or more and 100 nm or less. If it is less than 2 nm, the peel strength after thermal load may be insufficient, and if it is 100 nm or more, it is not preferable because it becomes difficult to remove the barrier layer when forming a wiring pattern by an etching method. More preferably, they are 3 nm or more and 50 nm or less, More preferably, they are 5 nm or more and 30 nm or less.

  On this, the seed layer 2 is laminated | stacked. The seed layer 2 can be laminated by the vacuum thin film method with the same composition and thickness as the seed layer 1.

    Further, a copper layer is laminated thereon by a vacuum thin film method. Lamination is preferably performed by sputtering. The thickness of the copper layer by sputtering is preferably 10 nm or more, more preferably 30 nm or more, and further preferably 50 nm or more. When the film thickness is less than 10 nm, it is not preferable because the copper film is likely to be eluted in the next copper plating process, and there is no particular upper limit, but from the viewpoint of productivity and thick lamination, heat loss in the sputtering process is not preferable. Therefore, the upper limit is about 200 nm, preferably 120 nm or less.

A thicker copper layer is formed on these metal thin films by electrolytic or electroless plating. A copper plating process consists of the process of degreasing and copper plating for improving adhesiveness. Current density for the electrolytic plating is preferably ^{0.2~10A / dm 2, 0.5~5A / dm} 2 is more preferable. The thickness of the formed copper layer is preferably 3 to 20 μm, and more preferably 4 to 12 μm. If the thickness is less than 3 μm, the resistance value of the thin wire when the wiring pattern is formed tends to be high, and if the thickness exceeds 20 μm, it takes time to form a film, resulting in poor economics. It is not preferable in terms of quality because it tends to proceed and there is a risk of disconnection due to bending. Although it depends on the current density of the target circuit, the thickness is more preferably about 6 to 10 μm from the viewpoint of workability and quality. The plating conditions vary depending on the composition of the plating bath, current density, bath temperature, stirring conditions, etc., but are not particularly limited. The plating bath is preferably a copper sulfate bath, a copper pyrophosphate bath, a copper cyanide bath or the like, but is not limited thereto.

The peel strength T1 between the copper layer and the polyimide layer in the normal state of the copper polyimide laminated film of the present invention is 5. in terms of the thickness of the copper layer of 8.5 μm because of the mechanical stability of the thin wire after the wiring pattern is formed. It is preferably 0 N / cm or more. More preferably, it is 6.0 N / cm or more. The upper limit of the peel strength is not specified, but is usually about 10.0 N / cm in terms of the thickness of the copper layer of 8.5 μm. The peel strength is the tensile strength when the copper layer is pulled in a direction perpendicular to the polyimide surface and peeled off, and according to a so-called 90 degree peel method, the peel strength depends on the thickness of the copper layer, When the thickness of the copper layer is increased, the peel strength is increased. Therefore, in order to compare the peel strength, it is necessary to set a standard thickness. The standard thickness is set to 8.5 μm, and the thickness before and after the standard thickness is applied to a formula converted to 8.5 μm, and the comparison is evaluated. Measure the peel strength of a sample with a film thickness of about 8.5 μm, create a relational expression between the film thickness and the peel strength, and calculate the peel strength when the film thickness is 8.5 μm (the conversion method is As described later).
The peel strength T2 after the heat treatment was obtained by measuring the peel strength by a 90-degree peel method in the same manner after forming a wiring pattern and performing heat treatment at 150 ° C. for 168 hours in a hot air oven. is there. The standard thickness is set to 8.5 μm, and the thickness before and after the standard thickness is applied to a formula for conversion to a thickness of 8.5 μm for calculation and comparative evaluation.

    T2 / T1 of 0.6 or more means that the peel strength T2 after heating at 150 ° C. for 168 hours is maintained at 60% or more of the initial normal peel strength T1. This means that it can maintain a certain level of peeling strength against the thermal load when processed into a substrate or the like, and can ensure mechanical stability. More preferably, T2 / T1 is 0.65 or more, and further preferably 0.7 or more.

Hereinafter, the copper polyimide laminated film of the present invention will be described in detail by way of examples.
Each characteristic value in the examples was measured by the following measurement method.
(1) Peel strength T1 (N / cm) in normal state
In accordance with JIS C6471-1995 section 8.1 “Peeling strength of copper foil”, method A, the peeling strength by 90 ° peeling was evaluated. A release film on one side of a dry film resist (LF1615: manufactured by Hitachi Chemical Co., Ltd., 15 μm) is peeled off from the copper surface side of the copper polyimide laminated film, and a roll temperature of 110 ° C. is applied by a pressure roller type laminator (Lamipacker LLP650: manufactured by Fuji Plastics). Bonding, aligning the mask pattern, and exposing by irradiating ultraviolet rays from the pattern side. The unexposed portion of the dry film resist is dissolved with an aqueous sodium hydrogen carbonate solution to develop the resist pattern. Further, the exposed copper layer is soaked in a ferric chloride aqueous solution, and after washing with water, the resist is dissolved and removed with a 10% aqueous sodium hydroxide solution. The 0.8 mm wide copper pattern created in this way was affixed to a German wheel type jig, the copper foil part was set on a cross head of Tensilon (RTC-1150A: manufactured by Orientec), and a tensile speed of 10 cm / min. The tensile strength at the time of peeling was measured.

    The thickness of the copper layer was measured with an electronic micrometer (MH-15M / TC-101: made by Nikon), and the level difference of the copper layer after the above etching was measured, and the thickness t was measured in the range of 7.5 to 9.5 μm Using the peel strength value T (N / cm) thus obtained, a linear regression equation T = at + b (a and b are coefficients) was obtained, and the peel strength converted to 8.5 μm thickness was calculated.

(2) Peel strength after heat treatment T2 (N / cm)
After forming the 0.8 mm width copper layer pattern, heat treatment is performed at 150 ° C. for 168 hours in a hot air oven (ST-110: manufactured by ESPEC), and then peel strength after heat treatment by peeling at 90 ° T2 Was measured.

Example 1
Aromatic tetracarboxylic anhydride consisting of pyromellitic dianhydride and 3,3 ′, 4,4′-diphenyltetracarboxylic dianhydride, aromatic consisting of 4,4′-diaminodiphenyl ether and paraphenylenediamine A “Kapton” (registered trademark) 150EN-C (manufactured by Toray DuPont) polyimide film containing diamine as a main component was used. The thickness of the film was 38.6 μm.

  On this film surface, a nickel / chromium alloy (nickel 80 wt% / chromium 20 wt%) target was used, and a 25 nm nickel / chromium alloy seed layer 1 was laminated by DC sputtering. Next, using a target of indium tin oxide (indium oxide 90 wt% / tin oxide 10 wt%), a barrier layer was deposited to a thickness of 12 nm by DC sputtering. Further, using a nickel / chromium alloy target (nickel 80 wt% / chromium 20 wt%), a seed layer 2 of 25 nm nickel / chromium alloy was laminated by DC sputtering.

  A copper layer was laminated thereon by an 80 nm sputtering method, and then electrolytic copper plating with a thickness of 8.5 μm was performed on the sputtered layer. The actual thickness of the plated copper layer was measured with an electronic micrometer at the level difference from the polyimide film after etching the copper layer, and the peel strength in terms of thickness was determined by a conversion formula.

  The normal peel strength was good at 6.7 N / cm, the peel strength after heating at 150 ° C. for 168 hours was 6.2 N / cm, and T2 / T1 was 0.93, good.

(Example 2)
“Kapton” (registered trademark) 150EN-C (manufactured by Toray DuPont) polyimide film was used. The thickness of the film was 38.3 μm.

  On this film surface, a nickel / chromium alloy (nickel 95 wt% / chromium 5 wt%) target was used to deposit a 12 nm nickel / chromium alloy seed layer 1 by DC sputtering. Next, using a target of indium tin oxide (indium oxide 90 wt% / tin oxide 10 wt%), a barrier layer was deposited to a thickness of 12 nm by DC sputtering. Further, using a nickel / chromium alloy target (nickel 95 wt% / chromium 5 wt%), a 12 nm nickel / chromium alloy seed layer 2 was laminated by DC sputtering.

  A copper layer was laminated thereon by an 80 nm sputtering method, and then electrolytic copper plating with a thickness of 8.5 μm was performed on the sputtered layer. The actual thickness of the plated copper layer was measured with an electronic micrometer at the level difference from the polyimide film after etching the copper layer, and the peel strength in terms of thickness was determined by a conversion formula.

    The normal peel strength was good at 6.1 N / cm, the peel strength after heating at 150 ° C. for 168 hours was also 5.7 N / cm, and T2 / T1 was good at 0.93.

(Example 3)
“Kapton” (registered trademark) 150EN-C (manufactured by Toray DuPont) polyimide film was used. The film thickness was 38.5 μm.

On this film surface, a nickel / chromium alloy (nickel 80 wt% / chromium 20 wt%) target was used, and a 25 nm nickel / chromium alloy seed layer 1 was laminated by DC sputtering. Next, using a ZnSSiO ₂ target, a 12 nm barrier layer was deposited by DC sputtering. Further, using a nickel / chromium alloy target (nickel 80 wt% / chromium 20 wt%), a seed layer 2 of 25 nm nickel / chromium alloy was laminated by DC sputtering.

  A copper layer was laminated thereon by an 80 nm sputtering method, and then electrolytic copper plating with a thickness of 8.5 μm was performed on the sputtered layer. The actual thickness of the plated copper layer was measured with an electronic micrometer at the level difference from the polyimide film after etching the copper layer, and the peel strength in terms of thickness was determined by a conversion formula.

    The normal peel strength was good at 5.9 N / cm, the peel strength after heating at 150 ° C. for 168 hours was 4.8 N / cm, and T2 / T1 was good at 0.81.

Example 4
“Kapton” (registered trademark) 150EN-C (manufactured by Toray DuPont) polyimide film was used. The film thickness was 38.5 μm.

On this film surface, a nickel / chromium alloy (nickel 80 wt% / chromium 20 wt%) target was used, and a 25 nm nickel / chromium alloy seed layer 1 was laminated by DC sputtering. Next, a barrier layer of 12 nm was laminated by RF sputtering using an Al ₂ O ₃ target. Further, using a nickel / chromium alloy target (nickel 80 wt% / chromium 20 wt%), a seed layer 2 of 25 nm nickel / chromium alloy was laminated by DC sputtering.

  A copper layer was laminated thereon by an 80 nm sputtering method, and then electrolytic copper plating with a thickness of 8.5 μm was performed on the sputtered layer. The actual thickness of the plated copper layer was measured with an electronic micrometer at the level difference from the polyimide film after etching the copper layer, and the peel strength in terms of thickness was determined by a conversion formula.

The normal peel strength was good at 6.0 N / cm, the peel strength after heating at 150 ° C. for 168 hours was 4.8 N / cm, and T2 / T1 was good at 0.80.
(Example 5)
As the polyimide film, “UPILEX” (registered trademark) 35SGA (manufactured by Ube Industries) was used. The film thickness was 34.5 μm. In a nitrogen gas atmosphere, RF plasma treatment was performed at a treatment intensity of 500 Wmin / m ² at a pressure of 5 × 10 ⁻³ Pa. A sample was produced on the treated surface in the same manner as in Example 1.

  The normal peel strength was good at 6.6 N / cm, the peel strength after heating at 150 ° C. for 168 hours was 5.1 N / cm, and T2 / T1 was as good as 0.77.

(Comparative Example 1)
“Kapton” (registered trademark) 150EN-C (manufactured by Toray DuPont) polyimide film was used. The thickness of the film was 38.3 μm.

  On this film surface, a nickel / chromium alloy (nickel 80 wt% / chromium 20 wt%) target was used, and a 25 nm nickel / chromium alloy seed layer 1 was laminated by DC sputtering. A copper layer was laminated thereon by an 80 nm sputtering method, and then electrolytic copper plating with a thickness of 8.5 μm was performed on the sputtered layer. The actual thickness of the plated copper layer was measured with an electronic micrometer at the level difference from the polyimide film after etching the copper layer, and the peel strength in terms of thickness was determined by a conversion formula.

    The normal peel strength was 5.3 N / cm, but the peel strength after heating at 150 ° C. for 168 hours was 3.5 N / cm, and T2 / T1 was poor at 0.55.

(Comparative Example 2)
“Kapton” (registered trademark) 150EN-C (manufactured by Toray DuPont) polyimide film was used. The thickness of the film was 38.3 μm. On this film surface, a nickel / chromium alloy (nickel 80 wt% / chromium 20 wt%) target was used, and a 25 nm nickel / chromium alloy seed layer 1 was laminated by DC sputtering. Next, using a target of indium tin oxide (indium oxide 90 wt% / tin oxide 10 wt%), a barrier layer was deposited to a thickness of 12 nm by DC sputtering.

  A copper layer was laminated thereon by an 80 nm sputtering method, and then electrolytic copper plating with a thickness of 8.5 μm was performed on the sputtered layer. The actual thickness of the plated copper layer was measured with an electronic micrometer at the level difference from the polyimide film after etching the copper layer, and the peel strength in terms of thickness was determined by a conversion formula.

    The normal peel strength was as good as 5.4 N / cm, but the peel strength after heating at 150 ° C. for 168 hours was 1.7 N / cm, and T2 / T1 was poor at 0.31. It was.

(Comparative Example 3)
“Kapton” (registered trademark) 150EN-C (manufactured by Toray DuPont) polyimide film was used. The thickness of the film was 38.3 μm. A barrier layer of 12 nm was laminated on the film surface by a DC sputtering method using a target of indium tin oxide (indium oxide 90 wt% / tin oxide 10 wt%). Further, using a nickel / chromium alloy target (nickel 80 wt% / chromium 20 wt%), a seed layer 2 of 25 nm nickel / chromium alloy was laminated by DC sputtering.

  A copper layer was laminated thereon by an 80 nm sputtering method, and then electrolytic copper plating with a thickness of 8.5 μm was performed on the sputtered layer. The actual thickness of the plated copper layer was measured with an electronic micrometer at the level difference from the polyimide film after etching the copper layer, and the peel strength in terms of thickness was determined by a conversion formula.

    The normal peel strength was poor at 3.0 N / cm, the peel strength after heating at 150 ° C. for 168 hours was 2.9 N / cm, and T2 / T1 was 0.97.

(Comparative Example 4)
“Kapton” (registered trademark) 150EN-C (manufactured by Toray DuPont) polyimide film was used. The thickness of the film was 38.3 μm. A barrier layer of 12 nm was laminated on the film surface by a DC sputtering method using a target of indium tin oxide (indium oxide 90 wt% / tin oxide 10 wt%).

  A copper layer was laminated thereon by an 8.50 nm sputtering method, and then, electrolytic copper plating with a thickness of 8.5 μm was performed on the sputtered layer. The actual thickness of the plated copper layer was measured with an electronic micrometer at the level difference from the polyimide film after etching the copper layer, and the peel strength in terms of thickness was determined by a conversion formula.

    The normal peel strength was poor at 2.9 N / cm, the peel strength after heating at 150 ° C. for 168 hours was 2.8 N / cm, and T2 / T1 was 0.97.

(Comparative Example 5)
“Kapton” (registered trademark) 150EN-C (manufactured by Toray DuPont) polyimide film was used. The thickness of the film was 38.3 μm. In a nitrogen gas atmosphere, RF plasma treatment was performed at a treatment intensity of 500 Wmin / m ² at a pressure of 5 × 10 ⁻³ Pa. A sample was prepared on the treated surface in the same manner as in Comparative Example 4.

  The normal peel strength was as poor as 3.0 N / cm, the peel strength after heating at 150 ° C. for 168 hours was 2.8 N / cm, and T2 / T1 was 0.93.

  The above Examples and Comparative Examples are summarized in Table 1.

    Since it has excellent adhesion to the base material and adhesion after heat load, it has high utility value in the field corresponding to miniaturization of electronic devices.

Claims (6)

  On the polyimide film, a seed layer 1 made of an alloy of nickel and chromium, a barrier layer, a seed layer 2 made of an alloy of nickel and chromium, and a copper layer are formed in this order by a vacuum thin film method, and a plating method is further formed thereon. A copper polyimide laminated film in which a copper layer is laminated.   The copper polyimide laminated film according to claim 1, wherein the barrier layer is a metal oxide.   3. The copper polyimide laminated film according to claim 1, wherein the metal oxide is tin oxide, indium oxide, or indium tin oxide. The film thickness of each of the seed layer 1, the barrier layer, and the seed layer 2 is 2 nm to 100 nm, and the peel strength T1 between the copper layer and the polyimide film in a normal state is converted to a thickness of 8.5 μm of the copper layer. It is 5.0 N / cm or more, The copper polyimide laminated film in any one of Claim 1 to 3 characterized by the above-mentioned. The thickness of the seed layer 1, the barrier layer, and the seed layer 2 is 2 nm or more and 100 nm or less, and the ratio T2 / T1 between the peel strength T1 in a normal state and the peel strength T2 after heat treatment at 150 ° C. for 168 hours 5 is 0.6 or more, The copper polyimide laminated film according to any one of claims 1 to 4. The polyimide film comprises an aromatic tetracarboxylic acid anhydride comprising pyromellitic dianhydride and 3,3 ′, 4,4′-diphenyltetracarboxylic dianhydride, 4,4′-diaminodiphenyl ether, and paraphenylene. 6. The copper polyimide laminated film according to claim 1, comprising an aromatic diamine composed of diamine as a main component.