JP2003283099A - Method for manufacturing film substrate for circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a film substrate for a circuit which can realize a film substrate for a circuit as a flexible base substance of stable quality, at a low cost. <P>SOLUTION: On one flat surface or both flat surfaces of a flexible resin film like a liquid crystal polymer film 10 a sputtered layer excellent in adhesion like a comparatively thin copper sputtered layer 11 is closely formed by sputtering. In a vacuum, continuously, a copper deposition layer 12 is closely formed on the sputtered layer 11 by deposition. A sum of thickness of the sputtered layer 11 and the copper deposition layer 12 is set in a range of 0.5-12 μm, thereby enabling excellent film formation which is excellent in adhesion to the flexible resin film and has no pin holes. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a circuit film substrate suitable as a base material for a flexible wiring substrate.

[0002]

2. Description of the Related Art A flexible substrate composed of a flexible resin film and copper has been described in Japanese Patent Application No. 2001-223868 proposed by the present applicant, in which copper is thermocompression-bonded to a thermoplastic flexible resin film such as a liquid crystal polymer. Either by increasing the thickness by plating on a thin copper film formed on a flexible resin film by sputtering or vapor deposition, or by applying a resin on a copper foil and then reacting and drying it to form an insulating layer. Manufactured.

Among the above methods, there are the following problems in the method of thermocompression-bonding copper on a thermoplastic flexible resin film such as a liquid crystal polymer and the method of coating a resin on a copper foil and then causing the resin to react and dry.

In order to increase the adhesion between the thermoplastic flexible resin film such as liquid crystal polymer or the insulating resin and the copper foil, it is necessary to finely roughen the adhesion surface of the copper foil. The converted portion also needs to be etched. That is, the joint surface between the thermoplastic flexible resin film such as liquid crystal polymer and the copper foil has irregularities due to the roughening treatment, but it is necessary to sufficiently remove the copper in the irregularities. In this case, the side surface of the circuit is similarly etched, so that the minimum wiring width is restricted.

Further, the copper foil needs to be thin in order to form fine wiring, but the thin copper foil used in thermocompression bonding is difficult to manufacture due to insufficient mechanical strength due to its thinness, and the cost is high.

Further, as shown in FIG. 4, after forming a copper sputter layer 11 as a copper film on a flexible resin film 10 such as a liquid crystal polymer, a copper plating layer 15 is formed by electroplating to increase the thickness. There is such a problem.

Since the sputtering process is a vacuum process, the surface of the formed copper sputtered layer is very clean, but when the plating process is performed thereafter, the surface is oxidized and contaminated by oxygen, acid and other impurities in the air. . In addition, there is a possibility that the plating process may be contaminated with various chemicals. For these reasons, the adhesion between the sputtered underlayer and the plating layer may be reduced, or minute foreign matter or contamination may cause defects such as pinholes 16 in the plating layer as shown in FIG. It requires strict attention. Such a defect causes a fatal defect in fine wiring.

Further, the initial cost and maintenance cost of the plating apparatus, the attached pure water production apparatus, and the waste water treatment facility are enormous.

Further, increasing the copper thickness to a desired thickness by sputtering is not economical because the film forming rate of sputtering is low.

[0010]

In the method of increasing the thickness by copper plating after forming a copper film on the flexible resin film according to the above conventional example by sputtering,
It is difficult to form a copper thickness of 12 micrometers or less on a flexible resin film at low cost with high quality and stability.

When the copper thickness is increased by plating, a pretreatment is performed with an acid or the like to remove the oxide on the surface of the sputtered substrate, and the copper thickness is increased by electroplating, followed by washing with water to remove the plating solution. Drys but secures stable adhesion.
Prevention of defects such as pinholes is extremely difficult.

Further, in the plating process, the equipment cost of the plating apparatus main body, the pure water production apparatus, the exhaust treatment equipment, the waste water treatment equipment containing heavy metals, and the operation and maintenance costs thereof are enormous.

An object of the present invention is to solve the above problems and to provide a method for producing a circuit film substrate which can realize a circuit film substrate as a flexible base material of stable quality at a low cost. To do.

Other objects and novel features of the present invention will be clarified in the embodiments described later.

[0015]

In order to achieve the above object, a method for manufacturing a circuit film substrate according to claim 1 of the present invention is such that a flexible resin film has a thickness of 0 or less on one or both smooth surfaces of a flexible resin film by sputtering copper. After forming a copper sputter layer in the range of 0.02 to 1.0 micrometer in close contact, a copper vapor deposition layer is formed in close contact by vacuum deposition on the copper sputter layer, and the thickness of the copper sputter layer and the copper vapor deposition layer is formed. The sum of the sums is set in the range of 0.5 to 12 micrometers.

According to a second aspect of the present invention, there is provided a method for manufacturing a circuit film substrate, comprising: nickel, chromium, a nickel alloy, or chromium having good adhesion to the flexible resin film on one or both smooth sides of the flexible resin film by sputtering. Thickness of alloy or chromium oxide 10 to 10
After forming a sputter layer in the range of several hundred angstroms by adhesion, a copper deposition layer is formed by adhesion on the sputter layer in vacuum, and the sum of the thickness of the sputter layer and the copper deposition layer is 0.5 to The range is 12 micrometers.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the method for producing a circuit film substrate according to the present invention will be described below with reference to the drawings, taking a liquid crystal polymer as an example of a flexible resin film.

1 and 2 show an embodiment of a method for manufacturing a circuit film substrate according to the present invention. In these figures, reference numeral 10 denotes a flexible liquid crystal polymer film as a thermoplastic flexible resin film, and a copper film which is a lower layer copper film formed on the smooth one surface (or both surfaces) thereof by sputtering copper as shown in FIG. The sputter layer 11 is formed in close contact. Here, the thickness of the copper sputter layer 11 is in the range of 0.02 to 1.0 micrometer. If the thickness of the copper sputter layer 11 is less than 0.02 μm, the adhesion to the film 10 is insufficient and the strength is insufficient as a circuit board.
If it exceeds 0 μm, the time required for sputtering becomes long.

The liquid crystal polymer film 10 can use, for example, the trade name "Vectra" Kuraray Co., Ltd., and is a wholly aromatic polyester resin having a thickness of 25 or 50 micrometers. The thickness of the copper sputter layer 11 is 0.0
Considering that the film 10 is formed as thin as about 2 μm, it is desirable that the surface of the film 10 is as smooth as possible with unevenness of 0.02 μm or less. If the unevenness exceeds 0.02 μm, there is a risk of pinholes.

Since only the copper sputter layer 11 formed by sputtering on the liquid crystal polymer film 10 is too thin for a wiring circuit, copper is continuously vapor-deposited in vacuum to grow a sufficient thickness for the wiring circuit. That is,
A copper vapor deposition layer 12 to be an upper copper film is formed on the copper sputter layer 11 to a required thickness, and the sum of the thickness of the copper sputter layer 11 and the copper vapor deposition layer 12 is 0.5 to 12 micrometers. So that Below the lower limit of 0.5 to 12 micrometers, there is a problem that the film thickness is insufficient and the current capacity of the circuit is insufficient. Above the upper limit of this range, it is more economical to increase the thickness by other methods such as plating. Target.

To say that copper is vapor-deposited continuously in vacuum after sputtering means that the vacuum vapor-deposition treatment is carried out without taking out the liquid crystal polymer film 10 after the sputtering treatment into the atmosphere. After sputtering, copper is vapor-deposited in vacuum. By depositing copper sputtered layer 11 and copper deposited layer 1
A homogeneous copper film can be obtained without the inclusion of foreign matter such as oxides at the interface of 2.

Then, as shown in FIG. 2, a circuit 13 (wiring) is formed by partially leaving a copper film (a laminated structure of a copper sputter layer 11 and a copper vapor deposition layer 12) by etching based on a resist pattern formed by a photographic method. Pattern) is formed.
At this time, since the surface of the liquid crystal polymer film 10 on which the copper film is provided is an extremely smooth surface without unevenness (a surface that is not roughened) in comparison with the thickness of the copper film, the surface of the liquid crystal polymer film between the circuits The etching time of 14 can be shortened compared to the roughened surface, and the side surface of the wiring pattern is slightly corroded by etching. Further, in this manufacturing method, the thickness of copper can be reduced to a desired thickness, which is suitable as a fine wiring material.

Further, since the copper sputter and the copper vapor deposition are continuously performed in a vacuum, there is no defect at the interface between the copper sputter layer 11 and the copper vapor deposition layer 12, and therefore the pin which may be generated by the plating in the conventional example of FIG. Since defects such as the holes 16 can be minimized, fine wiring with few defects can be easily formed.

FIG. 3 shows an example of an apparatus for carrying out the manufacturing method shown in FIGS. 1 and 2. In this figure, the apparatus is provided with a container 20 whose inside is maintained in vacuum, and the container 20 has four chambers, that is, a film feeding chamber 21 and a sputtering chamber 2.
2. It has a vapor deposition chamber 23 and a film winding chamber 24 inside. The feeding roll 31 provided in the film feeding chamber 21 is a feeding means of the liquid crystal polymer film 10, and the liquid crystal polymer film 10 fed from here passes through the sputter chamber 22 and the vapor deposition chamber 23 to the film winding chamber 24. The liquid crystal polymer film 10 provided here is wound up by a winding roll 32 as a winding means.

In the sputter chamber 22, a plasma cleaning section 33 as a means for cleaning the surface of the liquid crystal polymer film and a sputter section 34 for forming a copper sputter layer on the liquid crystal polymer film by sputtering.
Is installed. If the surface of the liquid crystal polymer film is clean, the plasma cleaning unit 33 as a cleaning unit can be omitted. It is also possible to install a processing device for improving the adhesion.

A large-diameter cooling drum 35 and a vacuum vapor deposition section 36 facing the cooling drum 35 are installed in the vapor deposition chamber 23. The liquid crystal polymer film 10 is wound around the cooling drum 35 to run, and a copper vapor deposition layer is formed by stacking the liquid crystal polymer film 10 on the copper sputter layer of the liquid crystal polymer film by the vacuum vapor deposition section 36 facing the liquid crystal polymer film 10. The cooling drum 35 and the vacuum vapor deposition unit 36 facing the cooling drum 35 may be increased in number depending on the processing speed.

The liquid crystal polymer film 10 after the vapor deposition treatment is wound up by a winding roll 32.

Using the apparatus shown in FIG. 3, a copper sputtered layer 11 is formed on the liquid crystal polymer film 10 by sputtering, and subsequently, a copper deposited layer 12 is formed by vacuum evaporation.
Can be continuously formed.

According to this embodiment, the following effects can be obtained.

(1) In an adhesive composite material in which a copper foil is attached to a liquid crystal polymer film by a conventional thermocompression bonding method,
Innumerable fine protrusions on the surface of the film, which become an obstacle when creating a circuit with a fine pitch, can be eliminated by sputtering copper on the surface of the smooth liquid crystal polymer film 10. Further, by forming the copper sputter layer 11 on the liquid crystal polymer film 10 by sputtering, it is possible to form a copper film having sufficiently good adhesion even if the surface of the film 10 is smooth. Further, after forming the copper sputtered layer in close contact with the copper sputtered layer in vacuum, the copper vapor deposition layer is formed in close contact with the copper sputtered layer by vapor deposition, whereby a copper film having a required film thickness can be easily formed. Further, as compared with the case where the conventional composite material is used, since there is no uneven portion for improving the adhesive force on the film surface, etching can be performed only in an amount corresponding to the thickness of copper.
Therefore, the etching of the side surface of the circuit 13 shown in FIG. 2 is also reduced, so that the circuit can be formed without reducing the line width of the circuit.

(2) As shown in this embodiment, the liquid crystal polymer film 10 is used as the flexible resin film.
When used, the liquid crystal polymer film has a very small coefficient of thermal expansion and can change the coefficient of thermal expansion to some extent, so that the coefficient of thermal expansion of a glass substrate such as a semiconductor chip or a liquid crystal display panel should be as close as possible. You can In addition, the liquid crystal polymer film has very little hygroscopicity (water absorption 0.04%, moisture absorption dimensional stability 4ppm /% R
H) is a flexible substrate material that can reliably prevent electrode short circuit of the semiconductor chip or the display panel connecting portion. As described above, the liquid crystal polymer film is excellent as a base material for a flexible substrate, and by utilizing such characteristics of the liquid crystal polymer as a flexible circuit substrate, dimensional stability against humidity and temperature changes can be obtained. Improve COF (Chip On Flex or Film) and TAB (Tape A
It is possible to solve the problems in the manufacturing technology of utomated Bonding) and to implement higher density mounting.

In the above-mentioned embodiment, the copper vapor deposition layer is provided on the copper sputter layer, but as another embodiment,
Instead of a copper sputter layer, a liquid crystal polymer film 10 as a flexible resin film, nickel, chromium, a nickel alloy having good adhesion to polyimide or the like,
A film forming method in which a sputter layer made of a chromium alloy or chromium oxide is formed and a copper vapor deposition layer is subsequently formed thereon in vacuum may be used. The sputter layer is a few tens to a few
The thickness is in the range of 0 angstrom, and if the film thickness is less than the lower limit value of this range, insufficient adhesion or pinholes may occur, and if the film thickness exceeds the upper limit value, film formation takes time.
Other processes may be the same as those in the above-described embodiment.

Although the embodiment of the present invention has been described above, it is obvious to those skilled in the art that the present invention is not limited to this and various modifications and changes can be made within the scope of the claims. Ah

[0034]

As described above, according to the method for manufacturing a circuit film substrate according to the present invention, a copper sputter layer or nickel, chromium, nickel alloys, and chromium alloys are formed on one or both smooth surfaces of a flexible resin film. Alternatively, after a sputter layer made of chromium oxide is formed by adhesion, a copper deposition layer is formed by adhesion on the sputter layer in vacuum, and the circuit film substrate obtained by this method has a copper thickness by plating. As compared with the case where the increased number of composite materials is used, defects such as pinholes due to impurities between the sputter layer and the vapor deposition layer are extremely small, so that wiring having a narrow line width can be formed. Further, by vapor deposition after sputtering, it is possible to efficiently form a copper vapor deposition layer having a desired thickness suitable for fine wiring as compared with sputtering processing, and it is possible to form fine wiring at a relatively low cost. .

[Brief description of drawings]

FIG. 1 is an embodiment of a method for manufacturing a circuit film substrate according to the present invention, showing a state in which a copper film composed of a copper sputter layer and a copper vapor deposition layer is adhered and formed on a flexible resin film such as a smooth liquid crystal polymer. It is an expanded sectional view shown.

FIG. 2 is an enlarged cross-sectional view when a circuit is formed by etching copper in the embodiment.

FIG. 3 is a schematic configuration diagram showing an example of an apparatus for carrying out the manufacturing method shown in the embodiment.

FIG. 4 is an enlarged cross-sectional view showing a problem of a method of increasing a film thickness by electroplating after forming a copper base film on a flexible resin film such as a liquid crystal polymer.

[Explanation of symbols]

10 Flexible resin film such as liquid crystal polymer 11 Copper sputter layer 12 Copper deposition layer 13 circuits 14 Flexible resin film surface such as liquid crystal polymer 15 Copper plating layer 16 pinholes

Claims (2)

[Claims] 1. A flexible resin film having a thickness of 0.02 to 1.0 formed on one or both smooth surfaces by copper sputtering.
After forming a copper sputtered layer in the range of micrometer in close contact with the copper sputtered layer in vacuum, the copper sputtered layer is adhered to the copper sputtered layer by vapor deposition, and the total thickness of the copper sputtered layer and the copper deposited layer is set to 0. A method of manufacturing a film substrate for a circuit, wherein the film substrate has a thickness of 5 to 12 micrometers. 2. A flexible resin film having a thickness of 10 or more, which is made of nickel, chromium, a nickel alloy, a chromium alloy, or a chromium oxide, which has good adhesion to the flexible resin film by sputtering on one or both surfaces of the flexible resin film.
After forming a sputter layer in the range of up to several hundred angstroms by adhesion, a copper deposition layer is formed by adhesion on the sputter layer in vacuum, and the sum of the thickness of the sputter layer and the copper deposition layer is 0.5. A method of manufacturing a film substrate for a circuit, wherein the film substrate for a circuit is in the range of -12 μm.