JP2000228571A - Metal transfer film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metal transfer film which enables electrodes to be simply, securely formed, and the formed electrodes to be thinned, and further the electrodes to be formed at a low price. SOLUTION: A metal layer (parting metal layer) 2 having an oxidized surface as a mold release layer is formed on the surface of a plastic film, and a metal transfer layer 4 is formed on the oxidized surface 3. The use of such a metal transfer film allows a transfer metal layer 4 formed on the surface of the parting metal layer 2 to be simply, securely transferred to an object to be transferred. Thus, the electrodes of electronic parts can be formed at a low price.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a metal transfer film, and more particularly, to a metal transfer film used for forming electrodes of electronic components.

[0002]

2. Description of the Related Art Conventionally, as a method of forming an electrode of an electronic component, for example, in the production of a semiconductor circuit or the like, a metal layer is formed on a substrate by vapor deposition or plating and then patterned by photolithography. And, for example, in the production of multilayer ceramic capacitors and the like, on a ceramic green sheet,
There is known a method in which a conductive paste is pattern-coated by screen printing, and the coated ceramic green sheets are laminated and fired.

[0003]

However, in recent years, the electrodes of electronic components have been increasingly miniaturized and densified. Therefore, the electrodes used in the production of semiconductor circuits and the like have been used for vapor deposition, plating, or photolithography. The equipment for performing lithography also requires high-precision and expensive equipment, and accompanying this, the manufacturing process becomes complicated, thereby reducing productivity and increasing the cost for forming electrodes. Is coming.

[0004] Further, in the multilayer ceramic capacitor, there is a strong demand for high capacitance, and if the number of layers is increased to meet the demand, the size of the multilayer ceramic capacitor cannot be reduced. However, the method of forming electrodes by screen printing cannot respond to the demand for thinner electrodes in recent years.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and it is an object of the present invention to easily and reliably form an electrode, to reduce the thickness of the formed electrode, and to further reduce the thickness of the formed electrode. An object of the present invention is to provide a metal transfer film that can form an electrode at a low cost.

[0006]

In order to solve the above-mentioned object, the present invention provides a metal layer having an oxidized surface as a release layer on the surface of a plastic film (hereinafter abbreviated as a release metal layer). ), And a transfer metal layer (a metal layer transferred to an object) is provided on the oxidized surface of the metal transfer film.

[0007] The release metal layer may be formed by laminating a plurality of different metal layers.

Preferably, the transfer metal layer is processed into an electrode pattern of an electronic component.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The plastic film used for the metal transfer film of the present invention is not particularly limited as long as it has good adhesion to the release metal layer. A plastic film can be used. As such a plastic film,
For example, polyethylene film, polypropylene film, polystyrene film, polyvinyl chloride film, polyester film, polycarbonate film, polyimide film, polysulfone film, polyethersulfone film, polyamide film,
A polyether ketone film, a polyphenylene sulfide film and the like can be mentioned. It is preferable that these plastic films have a thickness of about 10 μm to 200 μm, particularly about 15 μm to 150 μm.

In the metal transfer film of the present invention, a release metal layer is formed on the surface of the plastic film as described above. The release metal layer serves as a release layer for the transfer metal layer formed thereon, has good adhesion to the plastic film, and has a release property for the transfer metal layer. It has. Aluminum (Al), copper (Cu), chromium (Cr), titanium (T
i), nickel (Ni), iron (Fe), cobalt (C
o), zirconium (Zr), silver (Ag), and alloys thereof.

Further, the release metal layer may be composed of one layer of a metal layer formed of the above-mentioned metal material, or may be a laminate of a plurality of metal layers of the same type or different types. When a plurality of layers are stacked, it is necessary that the interface between the metal layers is not oxidized so that the metal layers are not separated.

The release metal layer is generally formed by a known vacuum deposition method such as sputter deposition, resistance heating deposition, electron beam heating deposition, etc. In this case, the release metal layer and the plastic film are used. The surface of the plastic film can be subjected to plasma treatment in an atmosphere of argon, oxygen, nitrogen gas or the like for the purpose of improving the adhesion to the plastic film.

The oxidized surface of the release metal layer may be obtained by subjecting the metal surface formed by vapor deposition as described above to plasma treatment in an atmosphere containing oxygen or simply exposing the metal surface to the atmosphere. Formed by Alternatively, when the metal layer is formed by vapor deposition as described above, oxygen gas may be introduced into the atmosphere.

As a method other than vapor deposition of the release metal layer, wet plating is also possible. In this case, an oxide film is formed spontaneously without any treatment for oxidizing the surface metal layer. .

In the present invention, the thickness of the release metal layer is usually preferably in the range of 10 nm to 200 nm.

In the metal transfer film of the present invention, a transfer metal layer is formed on the oxidized surface of the release metal layer. The metal material for forming the transfer metal layer is not particularly limited, and a conventionally known metal material can be used. As such a metal material,
Depending on the application, for example, materials suitable for forming an electrode include gold (Au), silver (Ag), palladium (Pd), nickel (Ni), and indium (I
n), tin (Sn), copper (Cu), zinc (Zn), chromium (Cr), bismuth (Bi), antimony (Sb), lead (Pb), magnesium (Mg), aluminum (A
l) and alloys thereof.

Further, the transfer metal layer may be composed of one layer of a metal layer formed of the above-mentioned metal material, or may be a laminate of a plurality of metal layers of the same type or different types. When a plurality of layers are stacked, it is necessary that the interface between the metal layers is not oxidized so that the metal layers are not separated.

Such a transfer metal layer is formed by sputtering evaporation,
It can be formed by a known vacuum evaporation method such as resistance heating evaporation or electron beam heating evaporation, an electroplating method, or a combination thereof, but is more preferably formed by a vacuum evaporation method. Note that, even in the case of the above combination, it is preferable to first form the first metal layer by a vacuum evaporation method.

In the present invention, the thickness of the transfer metal layer varies depending on the application, but is usually about 300 nm to 20 nm.
A range of 00 nm is preferred.

When the transfer metal layer is formed by electroplating, it is preferable that the release metal layer serving as a base has as high a conductivity as possible. Either thicken to some extent, or high conductive copper, silver,
It is preferable to use aluminum or the like.

On the other hand, as will be described later, when the transfer metal layer is patterned by chemical etching or the like, it is preferable that the release metal layer serving as a base is not corroded during the chemical etching of the transfer metal layer. For example, when nickel is used for the transfer metal layer, a hydrochloric acid / nitric acid-based etchant is usually used as a chemical etchant, so that stainless steel or the like having corrosion resistance to such an etchant is used for the release metal layer. Preferably, it is used. However, stainless steel has lower conductivity than copper, silver, aluminum, and the like, and requires more time to form a somewhat thick material by vacuum evaporation.

Therefore, for example, when a nickel transfer metal layer is formed by an electroplating method and further subjected to pattern processing by chemical etching, the release metal layer serving as a base may be:
It is preferable that a second metal layer such as stainless steel having corrosion resistance to a nickel etchant be provided on a first metal layer such as copper, silver, or aluminum having high conductivity.

When the transfer metal layer is formed by the electroplating method as described above, the thickness of the first metal layer and the thickness of the second metal layer of the release metal layer are 30 to 100 nm. It is preferably about 50 nm. By doing so, it is possible to obtain a release metal layer having high conductivity and corrosion resistance to a nickel etching solution in a short time.

In the metal transfer film of the present invention, for example, as shown in FIG. 1, a release metal layer 2 is provided on one surface of a plastic film 1 and the release metal layer 2 is oxidized. It has a shape in which the transfer metal layer 4 is provided on the surface 3.

FIG. 2 shows a case where the release metal layer 2 is formed by laminating a plurality of different metal layers. In FIG. 2, the release metal layer 2 is composed of a first metal layer 6 directly in contact with the plastic film, and a second metal layer 7 provided on the first metal layer 6, and It has a shape in which a transfer metal layer 4 is provided on the oxidized surface 3 of the layer 7. And as the first metal layer, highly conductive copper,
Silver, aluminum and the like are preferable, and stainless steel is preferable as the second metal layer.

In FIGS. 1 and 2, when the transfer metal layer 4 is used as a circuit element such as an electrode of an electronic component,
The transfer metal layer 4 may be formed to have a desired pattern. As an example, FIG. 3 shows a case where the transfer metal layer 4 is pattern-formed on the metal transfer film shown in FIG. As a method of forming the patterned transfer metal layer 5, a transfer metal layer 4 is chemically etched in a metal transfer sheet in which the transfer metal layer 4 is formed on the entire surface of the release metal layer 2 as shown in FIG. Or the like (subtractive method), or after forming a resist having a pattern opposite to a desired pattern on the release metal layer 2, the above-described vacuum deposition is performed on the exposed release metal layer surface. The transfer metal layer 5 patterned by a method or plating can be formed (additive method).

By the way, conventionally, as a metal transfer film, a transfer metal sheet in which a transfer metal layer is provided on the surface of a plastic film coated with a fluororesin film or a silicone release agent has been proposed. ,
When the transfer metal layer is patterned by a subtractive method or an additive method, there is a problem that the transfer metal layer is peeled off during the processing. In this respect, the metal transfer film of the present invention does not cause such peeling, and therefore, before transferring the transfer metal layer to the object, as shown in FIG. Can be processed.

In order to transfer the transfer metal layer using the metal transfer film of the present invention, for example, the transfer metal layer is brought into contact with an object to be transferred, and the transfer metal layer is moved from the plastic film side to the transfer metal layer side. For example, the transfer metal layer may be separated from the oxidized surface of the release metal layer by applying an external force such as heat, ultrasonic waves, electromagnetic waves, or physical pressure, and transferred to the object. In this case, the transferability may be improved by providing an adhesive layer on the surface of the transfer metal layer or the surface of the object, or may be used in combination with a plurality of external forces described above. Good.

Although the use of the metal transfer film of the present invention is not particularly limited, it is mainly used for forming electrodes of electronic parts. For example, to form an electrode on a substrate such as a semiconductor circuit, the transfer metal layer of the metal transfer film of the present invention is brought into contact with a portion of the substrate where the electrode is to be formed, and the transfer metal layer is formed from the plastic film side as described above. The transfer may be performed by applying an external force toward the side. Further, in the case of forming an electrode of a multilayer electronic component such as an internal electrode of a multilayer ceramic capacitor, the transfer metal layer of the metal transfer film of the present invention is brought into contact with a portion of the ceramic green sheet where the electrode is to be formed, As described above, after transferring by applying an external force from the plastic film side to the transfer metal layer side, the green sheets to which the transfer metal layer has been transferred may be sequentially laminated and fired.

As described above, if the electrodes of the electronic parts are formed by using the metal transfer film of the present invention, the electrodes can be easily and reliably formed on the substrate in the production of a semiconductor circuit or the like. In the production of laminated electronic substrates, for example, a thin metal layer formed on the surface of a plastic film can be transferred as it is, so a thinner electrode is formed than when a conductive paste is applied to a ceramic green sheet by patterning. can do. Therefore, even if the number of layers is increased, a high-capacity product can be manufactured without increasing the size.
Therefore, it is possible to easily and inexpensively form electrodes for electronic components that require further miniaturization and higher density.

[0031]

The present invention will be described below more specifically with reference to examples and comparative examples.

(Example 1) Polyethylene having a thickness of 50 μm
4 × 10 on terephthalate (PET) film^-1P
In the Ar gas atmosphere of a, Cu is deposited by sputtering and deposited.
O in the last stage of _TwoIntroduce 12% gas to Ar gas
Then, as a release metal layer, the surface is oxidized to a thickness of 70 nm.
Was formed. Next, the release metal layer (Cu thin layer)
4x10 on the membrane)^-1In an Ar gas atmosphere of Pa,
A 50 nm thick Ni thin film is formed by sputtering evaporation.
Furthermore, Ni is electroplated on the Ni thin film.
By plating to a thickness of 1000 nm, transfer gold
A metal transfer film was obtained by forming a metal layer.

Example 2 A Cr thin film having a thickness of 30 nm was formed on a polyimide film having a thickness of 50 μm in a 4 × 10 ^-1 Pa Ar gas atmosphere by sputter deposition. By exposing, the surface of the Cr thin film was oxidized to form a release metal layer. Next, on this release metal layer (Cr thin film), a Cu thin film having a thickness of 50 nm was formed by sputtering vapor deposition in an Ar gas atmosphere of 4 × 10 ^-1 Pa. Furthermore, by plating Cu to a thickness of 5000 nm on the Cu thin film by an electroplating method,
A transfer metal layer was formed to obtain a metal transfer film.

Example 3 A Cu film was placed on a polyimide film having a thickness of 50 μm in an Ar gas atmosphere of 4 × 10 ^-1 Pa.
Is sputter-deposited, and O ₂ gas is Ar
A 70% -thick Cu thin film whose surface was oxidized was formed as a release metal layer by introducing 12% with respect to the gas. next,
On this release metal layer (Cu thin film), a Ni thin film having a thickness of 50 nm is formed by sputtering vapor deposition in an Ar gas atmosphere of 4 × 10 ^-1 Pa, and subsequently, a Ni thin film having a thickness of 5 nm is formed in the same atmosphere.
A Cu thin film having a thickness of 0 nm is formed by sputter deposition.
To form a transfer metal layer consisting of a Ni layer and a Cu layer to obtain a metal transfer film.

(Example 4) On a PET film having a thickness of 50 μm, an Ar gas atmosphere of 4 × 10 ^-1 Pa was used to form a film having a thickness of 5 μm.
A Cu thin film having a thickness of 0 nm is formed by sputter deposition, and subsequently, a 30-nm thick stainless steel (SUS
304) A thin film was formed by sputtering deposition, and once exposed to the atmosphere, the surface of the stainless thin film was oxidized to form a release metal layer. Next, Ni is plated to a thickness of 600 nm by electroplating on the release metal layer (which is formed by laminating a stainless thin film on a Cu thin film) to form a transfer metal layer. I got

(Example 5) A polyimide film having a thickness of 50 μm was placed on a polyimide film in an Ar gas atmosphere of 4 × 10 ^-1 Pa in a C atmosphere.
u is sputter-deposited, and O ₂ gas is
12% was introduced with respect to r gas, and a 70-nm-thick Cu thin film whose surface was oxidized was formed as a release metal layer. Next, 4 × 10 ⁻¹ P is formed on the release metal layer (Cu thin film).
In the Ar gas atmosphere of a, a Ni thin film having a thickness of 30 nm was formed by sputter deposition. Subsequently, after forming a resist having a pattern opposite to a predetermined electrode pattern on the Ni thin film, the exposed Ni thin film surface is processed into an electrode pattern by plating Ni to a thickness of 800 nm by an electroplating method. The transferred metal layer was formed, and thereafter, the resist was removed, and the Ni thin film formed by the above-mentioned sputter deposition exposed between the electrode patterns was removed by etching to obtain a metal transfer film.

(Comparative Example 1) O ₂ during sputtering deposition of Cu
A metal transfer film was obtained in the same manner as in Example 1, except that no gas was introduced.

Comparative Example 2 A metal transfer film was obtained in the same manner as in Example 2 except that the Cr thin film was not exposed to the air.

Comparative Example 3 4 × 10 ^-1 P was placed on a 50 μm-thick PET film coated with a silicone release agent.
In the Ar gas atmosphere of a, a Ni thin film having a thickness of 80 nm is formed by sputtering deposition, and further, Ni is plated to a thickness of 1000 nm by electroplating on the Ni thin film to form a transfer metal layer. Thus, a metal transfer film was obtained.

(Evaluation of Metal Transfer Film)
4, and applying a photosensitive resist on the surface of the transfer metal layer of the metal transfer film of Comparative Examples 1 to 3, pattern exposure,
By developing, an etching resist having the same pattern as the predetermined electrode pattern was formed. Next, after the exposed transfer metal layer was chemically etched, the etching resist was removed, and finally 300 electrode patterns having a size of 1 mm × 2 mm were formed in an area of 5 cm × 5 cm. At this stage, in Comparative Example 3, the electrode pattern was partially peeled off. Otherwise, the electrode pattern could be completely formed. Next, the transfer metal layer of the metal transfer film and the pressure-sensitive adhesive sheet (50 μm PET film coated with an acrylic pressure-sensitive adhesive) are adhered to each other, and then peeled off again to improve the transferability of the electrode pattern. evaluated. Further, the metal transfer film obtained in Example 5 was similarly evaluated. As a result, all the electrode patterns of the metal transfer films of Examples 1 to 5 were completely transferred to the adhesive sheet, whereas the metal transfer films of Comparative Examples 1 and 2 were not transferred at all. Note that the Ni layer and the C
The transfer metal layer composed of the u layer did not peel at the interface between the Ni layer and the Cu layer, but peeled off at the interface between the Ni layer of the transfer metal layer and the release metal layer, and was well transferred.

[0041]

As described above, the metal transfer film of the present invention has good transferability, and can easily and reliably transfer a transfer metal layer to an object to be transferred. And such a metal transfer film of the present invention can be preferably used mainly for forming an electrode of an electronic component,
Electrodes can be formed at low cost. Further, as shown in FIG. 3, the transfer metal layer is formed by chemical etching or the like.
Even in the case of processing into a predetermined pattern, the transfer metal layer does not peel off from the release metal layer during the processing, so that the patterned transfer metal layer can be transferred.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one embodiment of a metal transfer film of the present invention.

FIG. 2 is a cross-sectional view showing an embodiment in a case where a release metal layer in the metal transfer film of the present invention is formed by laminating different kinds of metal layers.

FIG. 3 is a cross-sectional view showing one embodiment when a transfer metal layer is processed into an electrode pattern in the metal transfer film of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 plastic film 2 release metal layer 3 oxidized surface of release metal layer 4 transfer metal layer 5 transfer metal layer processed into electrode pattern

Claims (3)

[Claims] 1. A metal transfer film comprising: a metal layer having an oxidized surface as a release layer provided on a surface of a plastic film; and a transfer metal layer provided on the oxidized surface. 2. The metal transfer film according to claim 1, wherein the metal layer having an oxidized surface is formed by laminating a plurality of different metal layers. 3. The metal transfer film according to claim 1, wherein the transfer metal layer is processed into an electrode pattern of an electronic component.