JP2004009357A - Metallized / metallized laminated film and electronic parts using the same - Google Patents

Abstract

An object of the present invention is to provide a metal deposition / metal plating laminated film having very few projections on a metal surface and having excellent flatness.
Kind Code: A1 A metal deposition in which a conductive metal layer having a thickness of 0.5 μm or more and less than 9 μm is laminated on a metal deposition layer by electroplating, and an insulating layer having a thickness of less than 20 μm is provided on the conductive metal layer. / Achieved by metal-plated laminated film.
[Selection diagram] Fig. 1

Description

【図面の簡単な説明】
【図１】本発明のフレキシブルプリント配線用基板の好適なひとつの例の断面図を示す。
【符号の説明】
１：プラスチックフィルム
２：離型層
３：金属蒸着層
４：電気メッキ層
５：下地層
６：絶縁樹脂層[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a metal-deposited / metal-plated laminated film used for electronic components such as a substrate for flexible printed wiring and a film capacitor.
[0002]
[Prior art]
As electronic devices become smaller, lighter, more functional, more multifunctional, and densely packed, printed wiring boards are becoming more demanding due to the narrower conductor width and spacing between conductors, increased multilayer structure, increased flexibility, and thinner substrates. The density has been rapidly increasing, and the flexible printed circuit (hereinafter, referred to as FPC) substrate has been developed.
[0003]
2. Description of the Related Art Conventionally, a flexible printed wiring board having a three-layer structure in which a copper foil as a conductor layer is bonded to a polyimide film via an adhesive layer has been known. This three-layer structure type substrate has a problem that the heat resistance of the adhesive used is inferior to that of the plastic film, so that the dimensional accuracy after processing is reduced, and the thickness of the copper foil used is usually 10 μm or more. Therefore, there is a disadvantage that patterning for high-density wiring with a narrow pitch is difficult. Further, when mounting the IC, the adhesive is melted or thermally decomposed to the IC heated to a high temperature, so that the bumps of the IC and the leads on the FPC cannot be accurately connected. Therefore, when mounting an IC, it is common to make a hole at the position where the IC is mounted by punching or the like so that no adhesive is interposed under the IC chip.
[0004]
On the other hand, a metal layer as a conductor layer is formed on a plastic film by a wet plating method or a dry plating method (for example, a vacuum deposition method, a sputtering method, an ion plating method, etc.) without using an adhesive, and then electroplating. 2. Description of the Related Art A two-layer structure type flexible printed wiring board provided with a metal layer is known. These two-layer type flexible printed wiring boards that do not use an adhesive do not have an adhesive, so the IC is directly mounted on a plastic film without making a hole in the film surface when mounting the IC as described above. It is possible to do. Further, since the conductor layer of this two-layer structure type substrate can be made thinner than 9 μm, the flexibility of the FPC is very good and high-density wiring is possible.
[0005]
However, on the metal surface of the substrate material obtained in this way, protrusions or dents are generated due to abnormal deposition of the metal generated in the plating process, and these are failures in high-density wiring such as disconnection of wiring and short-circuit between wiring. Therefore, there is a drawback that the yield is lowered.
[0006]
Further, as high-density wiring and flexible substrates have progressed, thinner plastic films have been required. However, a polyimide film formed through a solution film forming process and then subjected to an imidization process has a thickness of less than 20 μm, and is poor in flatness. There is a disadvantage that these failures are promoted in the plating step and cannot be used in the subsequent steps such as patterning of printed wiring.
[0007]
[Problems to be solved by the invention]
The problem to be solved by the present invention is to provide an FPC substrate material of a two-layer plating method that does not use an adhesive, and has no protrusions or dents that pose a practical problem on the metal surface, particularly the copper surface. It is an object to provide a metal deposition / metal plating laminated film having a thickness of less than 9 μm and a resin layer such as a polyimide film serving as a substrate having a thickness of less than 20 μm, having good dimensional accuracy after processing, and capable of high-density wiring. It is assumed that.
[0008]
[Means for Solving the Problems]
This can be achieved by laminating a conductive metal layer having a thickness of 0.5 μm or more and less than 9 μm on the metal deposition layer by electroplating, and providing an insulating layer having a thickness of less than 20 μm on the conductive metal layer.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
In the present invention, a conductive metal layer having a thickness of 0.5 μm or more and less than 9 μm is laminated on the metal deposition layer by electroplating, and an insulating layer having a thickness of less than 20 μm is provided on the conductive metal layer.
[0010]
Hereinafter, the metal deposition / metal plating laminated film of the present invention and the method for producing the same will be described in detail.
[0011]
In the present invention, before forming a thicker metal layer by an electroplating method, a metal deposition layer is formed by a vacuum deposition or sputtering method. In the case of industrial production, vacuum deposition at a high processing speed, that is, high productivity is desirable. As the metal constituting the metal vapor deposition layer and the metal layer in the plating method, a metal selected from copper, nickel, tin, chromium and alloys thereof is preferable, and thereby, a layer having low resistance and rich in flexibility. Can be formed.
[0012]
The thickness of the metal deposition layer provided by vapor deposition or sputtering is 10 to 300 nm, preferably 30 to 120 nm, more preferably 40 to 100 nm. When the film thickness is smaller than 10 nm, the film is easily eluted in the metal plating step, and when the film thickness is larger than 300 nm, the film used as the base material is deformed by heat during the vacuum deposition or the sputtering step, so-called, It is easy to lose heat. Preferably, the surface of the metal thin film has a resistance of 1.0 Ω / cm or less (a resistance measured at a distance between terminals of 1 cm is 1.0 Ω or less).
[0013]
In the present invention, it is preferable that the roughness of the surface of the deposited metal is less than 60 nm in Ra. Further, it is preferable that the number of protrusions (or dents) having a height (or depth) of 3 μm or more on the surface of the deposited metal is less than 0.5 in a 10 cm square, and the number of protrusions (or dents) of 3 μm or more is almost nonexistent. More preferred.
[0014]
In the present invention, a thicker metal layer is formed on a metal thin film by electrolytic plating. The electrolytic metal plating step includes the steps of degreasing and acid activating treatment for improving adhesion, metal strike, and metal plating. When the electroplating process is started immediately after the deposition of the metal thin film, the degreasing and the acid activation treatment and the metal strike may be omitted. The current density for feeding the thin metal layer is preferably 0.2 to 10 A / dm2, and more preferably 0.5 to 5 A / dm2. Further, electroless plating can be performed in addition to electrolytic plating.
[0015]
In the present invention, the thickness of the formed metal plating layer needs to be 0.5 or more and less than 9 μm, and more preferably 1.0 to 8 μm. If it is less than 0.5 μm, the reliability of the plating layer cannot be said to be sufficient. If the thickness is 9 μm or more, it takes a long time to form a film, the economic efficiency is poor, and the etching of the end of the circuit pattern tends to proceed during the etching. Although it depends on the current density of the target circuit, it is more preferably about 1.0 to 8 μm from the viewpoint of processing workability and quality.
[0016]
In the present invention, plating conditions vary depending on the composition of the plating bath, current density, bath temperature, stirring conditions, and the like, but are not particularly limited. The plating bath includes a copper sulfate bath, a copper pyrophosphate bath, a copper cyanide bath, a nickel sulfamate bath, a tin-nickel alloy plating bath, a copper-tin-zinc alloy plating bath, a tin-nickel-copper alloy plating bath, and the like. Preferred, but not limited to. After the etching, noble metal plating such as gold cyanide plating, silver cyanide plating, rhodium plating, and palladium plating may be additionally formed on the terminals.
[0017]
In the present invention, if necessary, on the metal plating layer, to prevent diffusion to the insulating layer provided after the metal layer, to prevent oxidation of the metal layer, to increase the adhesion to the metal plating layer and the like. For the purpose, a metal different from the metal used for the metal plating layer, for example, a metal such as Ni, Cr, Zn, Sn, Co, Ti or an alloy thereof, an oxide, or the like is vacuum-deposited, sputtered, electroless-plated, It can be attached as a base layer by a method such as electrolytic plating. The thickness of the underlayer is generally set to about 3 to 50 nm depending on the purpose. In addition, for the purpose of increasing the adhesion to the metal plating layer, it is also possible to perform a surface treatment of applying an insulating layer only on the very surface of the metal foil by an etching method.
[0018]
It is preferable to provide a polyimide resin, an epoxy resin, or a mixture thereof as an insulating layer on the metal plating layer. The insulating resin layer is preferably formed by wet coating. Prior to this, it is preferable to attach polyimide to the metal surface by electrodeposition, because pinholes in the insulating resin layer can be eliminated. Also, in the case of forming an insulating resin layer only by wet coating, it is preferable that pinholes can be eliminated by repeating coating a plurality of times. The resin constituting the insulating layer preferably has a glass transition temperature of 100 ° C. or more and less than 350 ° C. When the glass transition point is lower than 100 ° C., the insulating layer may be deformed or deteriorated due to the heat generated when the wiring pattern is cut or when an IC or other electronic component is mounted. Further, in the case of a resin having a temperature of 350 ° C. or higher, it may be difficult to form a film by coating. Further, an insulating layer can be formed over the base layer or the etching layer.
[0019]
Examples of the resin used as the insulating layer may basically be any resin suitable for wet coating. However, as an acid anhydride, biphthalic dianhydride (BPDA), pyromellitic dianhydride, or a diamine component A polymer obtained by polymerizing a combination of monomers such as oxydianiline (ODA) p-phenylenediamine and 1,3-bisaminophenoxyhexafluoropropane (Bis-A-AF) is preferably used. When an insulating layer is provided by electrodeposition, a polymer having a functional group (such as a carboxyl group) electrically charged in an aqueous solution introduced into a molecular chain is used.
[0020]
In the metal-deposited / metal-plated laminated film of the present invention, preferably, a release layer is provided on the surface of the plastic film, and a metal-deposited layer is provided thereon.
[0021]
Examples of the release layer substrate plastic film preferably used in the present invention include a polyester film, a polyphenylene sulfide film, a polyimide film, a polyparazic acid film, a polyether sulfone film, a polyether ether ketone film, an aromatic polyamide film, and a polyoxazole. Films and those selected from their halogen group or methyl group substituents are exemplified. Further, these copolymers and those containing other organic polymers may be used. Known additives such as a lubricant and a plasticizer may be added to these plastics.
[0022]
The plastic film preferably used in the present invention preferably has at least one surface with a surface roughness Ra of less than 40 nm, and has a height (or depth) of 2 μm or more with respect to an average line on the surface of the plastic film. Is preferably less than one in a 10 cm square.
[0023]
The thickness of the plastic film, which is a release layer substrate preferably used in the present invention, is about 6 to 125 μm, and a thickness of 12 to 50 μm is suitable.
[0024]
A silicone resin film, a fluororesin film, a polyolefin resin film, a wax resin film, a cellulose resin film, a melamine-based film are applied to the surface of the film to give a peeling force of 5 to 50 g / cm between the plastic film and the metal deposition layer. It is preferable to apply and dry a release layer such as a resin film, an acrylic resin film, or a mixed resin film thereof. Any application method can be used as long as it is a known coating method, and it is not particularly limited.
[0025]
By peeling off the thus obtained plastic film / release layer / metal deposition layer / insulating resin layer laminated film at the interface of the release layer / metal deposition layer, the metal deposition layer / insulating resin layer is laminated. A metal-deposited / metal-plated laminated film can be obtained.
[0026]
Next, the metal deposition / metal plating laminated film of the present invention is suitably used as a substrate for flexible printed wiring. In this case, a pattern is formed by etching. Specifically, an unnecessary portion of the metal is dissolved and removed by a chemical reaction to form a predetermined electric circuit figure. As the etchant, an aqueous solution of cupric chloride, ferric chloride, persulfates, hydrogen peroxide / sulfuric acid, alkali etchant, or the like can be used. In addition, a necessary portion of the metal to be left as a pattern is coated with an organic compound-based resist by a photographic method or a screen printing method, or is protected by plating a different metal-based resist to prevent dissolution of the metal. The metal-deposited / metal-plated laminated film of the present invention can form a finer pattern and can withstand a repeated bending of a product and various environmental tests.
[0027]
【The invention's effect】
As described above, the metal-deposited / metal-plated laminated film of the present invention is obtained by laminating a conductive metal layer having a thickness of 0.5 μm or more and less than 9 μm on a metal-deposited layer by electroplating, and less than 20 μm on the conductive metal layer. By providing the insulating layer having a thickness of 3 mm, it is possible to provide a metal deposition / metal plating laminated film excellent in smoothness without coarse projections on the metal surface. The metal-deposited / metal-plated laminated film according to the present invention can be used for all kinds of electronics such as computers, terminal equipment, telephones, communication equipment, measurement and control equipment, cameras, watches, automobiles, household appliances, home appliances, aircraft instruments, and medical equipment. Can be used in the field. It is also applicable to electronic components such as connectors and flat electrodes.
[0028]
【Example】
Hereinafter, the present invention will be described in detail with reference to examples.
[0029]
Each characteristic value in the examples was measured according to the following measurement method.
[0030]
1. Observe the area of 160 mm x 40 mm of the protrusions (dents) on the surface of the metal film with a stereo microscope of 40 times, count the protrusions and dents of one scale (approximately 25 μm) or more, and mark them with a needle or the like. . The projection (dent) portion of the marked portion is magnified to about 1000 to 3000 times (here, 1250 times or 2500 times) with a laser microscope (for example, VK8500 manufactured by Keyence Corporation) to create a profile that crosses the projection (dent). And height (depth) were measured. The data in Table 1 are obtained by converting the average values of the heights (depths) of these protrusions and dents at nine places in the visual field into 10 cm square.
[0031]
2. Product appearance A metal-deposited / metal-plated laminated film (500 mm width) was spread on a flat floor, and appearance defects such as wrinkles and folds were visually observed.
[0032]
3. Deposition metal layer surface roughness (Ra)
Using a light interference type surface roughness type (WYKO NT-1000), under the following conditions: Measurement magnification × 5.2
・ Measurement range 1.24mm × 0.94mm
It was measured.
[0033]
Example 1
A gravure coater is coated with a melamine-based release agent on a polyester film having a thickness of 50 μm and a width of 1000 mm (Lumirror T-70D, Toray Industries, Inc., surface roughness Ra = 28 nm, coarse projections having a height of 2 μm or more, 0.2 / 10 cm □). (Film thickness 0.2 μm) to obtain a release film. After this release film was cut into a width of 500 mm, copper of 60 nm was deposited using a vacuum deposition machine. The copper-deposited film was subjected to electrolytic copper plating with a thickness of 5 μm using a roll-to-roll electrolytic plating apparatus to form a conductive metal layer on the metal vapor-deposited layer. Further, a polyimide varnish (Ube Industries Iupitite UPA-N111) is repeatedly applied twice on the copper side of the copper-plated film with a reverse roll coater to a dry film thickness of 12 μm, and a polyimide film is formed on the copper side. did. The release film was peeled from the film laminate to obtain a conductive metal layer thin film polyimide laminate film having a structure of metal deposition / metal plating / polyimide resin laminate. There was no particular problem in the manufacturing process up to this point.
[0034]
Example 2
A sample was prepared in the same manner as in Example 1 except that the coating thickness of the polyimide resin layer was changed to 5 μm.
[0035]
Example 3
A melamine release agent is applied to a polyester film (thickness: 50 μm, width: 1000 mm) (Lumirror R72, Toray Industries, Inc., surface roughness Ra = 28 nm, height: 0.2 μm or more, 0.2 cm / 10 cm □) using a gravure coater. It was applied (thickness: 0.3 μm) to obtain a release film. After this release film was cut into a width of 500 mm, copper of 60 nm was deposited on the release material application surface using a vacuum deposition machine. Thereafter, electrolytic copper plating with a thickness of 8 μm was performed using a roll-to-roll electrolytic plating apparatus to form a conductive metal layer on the metal deposition layer.
[0036]
A nickel chromium alloy (Ni: Cr = 95: 5) is deposited to a thickness of 120 angstroms on the plated copper surface of the obtained laminated film by sputtering, and a polyimide varnish (Ube Industries Iupitite UPA-N111) is formed on the metal surface. ) Was repeatedly applied twice using a comma coater, followed by a drying and heating step to form a polyimide film having a thickness of 15 μm. The release film was peeled off from the obtained laminated film to obtain a metal deposition / metal plating / polyimide resin laminated film.
[0037]
Comparative Example 1
One side of a polyimide film "Kapton EN" (registered trademark of Toray DuPont) having a thickness of 12.5 μm and a width of 520 mm was subjected to plasma treatment. The plasma treatment was performed in a vacuum chamber having a degree of vacuum of 5 mPa or less, by introducing an argon gas up to 2.0 Pa and using RF power of 1.0 kW. Next, using a target of chromium 10% nickel 90%, a nickel chromium vapor-deposited layer having a thickness of 60 nm was formed on the plasma-treated surface of the polyimide film by sputtering to form a first metal vapor-deposited layer. Further, copper having a purity of 99.99% was sputter-deposited on the metal-deposited second layer to form a copper-deposited layer having a thickness of 100 nm. In this sputtering step, the winding tension was initially set to 50 N for a width of 520 mm, but wrinkles were generated due to heat loss (deformation due to the heat applied to the film during sputtering), and the winding tension had to be increased to 70 N. Although it was not obtained, wrinkles were not completely eliminated in this case as well.
[0038]
Thereafter, electrolytic copper plating with a thickness of 8 μm was performed using a roll-to-roll electrolytic plating apparatus to form a conductive metal layer on the metal deposition layer.
[0039]
Comparative Example 2
A sample was prepared in exactly the same manner as in Comparative Example 1 except that “Kapton EN” (registered trademark of Toray DuPont) having a thickness of 25 μm and a width of 520 mm was used as the polyimide film. In this case, no particular problem occurred in processing.
[0040]
Evaluation Results Table 1 shows the results of measurement of the number of metal surface protrusions (dents) and appearance inspection of the samples of Examples 1, 2, and 3 and Comparative Examples 1 and 2.
[0041]
[Table 1]

[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a preferred example of a flexible printed wiring board according to the present invention.
[Explanation of symbols]
1: plastic film 2: release layer 3: metal deposition layer 4: electroplating layer 5: base layer 6: insulating resin layer

Claims (10)

A metal characterized in that a conductive metal layer having a thickness of 0.5 μm or more and less than 9 μm is laminated by electroplating on a metal deposition layer, and an insulating layer having a thickness of less than 20 μm is provided on the conductive metal layer. Deposition / metal plating laminated film. 2. The metal deposition / metal plating laminated film according to claim 1, wherein the insulating layer provided on the conductive metal layer is a polyimide resin, an epoxy resin, or a mixture thereof. The metal-deposited / metal-plated laminated film according to claim 2, wherein the polyimide resin has a glass transition temperature of 100 ° C or more and less than 350 ° C. 3. The metal-deposited / metal-plated laminated film according to claim 1, wherein the insulator is formed by wet coating. The laminated film according to claim 1, wherein the insulating layer provided on the conductive metal layer is a thermotropic liquid crystal polymer. The metal-deposited / metal-plated laminated film according to any one of claims 1 to 5, wherein a release layer is provided on the surface of the plastic film, and a metal-deposited layer is provided thereon. The surface roughness of at least one surface of the plastic film according to claim 6 is less than 40 nm in Ra, and the height (or depth) with respect to the average line on the surface is 2 μm or more. The metallized / metal-plated laminated film according to claim 6, wherein the number is less than one. 8. The method according to claim 1, wherein the surface of the deposited metal has a roughness of less than 60 nm in Ra and a number of protrusions (or depressions) having a height (or depth) of 3 μm or more in a 10 cm square is less than 0.5. Metal deposition / metal plating laminated film. On the surface of the plastic film, a release layer is provided, a metal deposition layer is provided thereon, and a conductive metal layer having a thickness of 0.5 μm or more and less than 9 μm is laminated on the metal deposition layer by electroplating. 6. The method according to claim 1, wherein an insulating resin layer is coated on the conductive metal layer, and then the plastic film and the release layer are peeled off. Method. An electronic component using the metal deposition / metal plating laminated film according to claim 1.

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