JPH08260145A - Production of plastic substrate having conductive layer - Google Patents

Abstract

PURPOSE: To provide a process for producing a plastic substrate having a conductive layer contributing to a decrease in curling which arises at the plastic substrate while assuring electrical conductivity and moistureproof performance. CONSTITUTION: A base body 11 consisting of a PPS film is set on a base body holder 2 and a target object 12 consisting of a chromium plate is set on a target electrode 3. While a sputtering chamber 4 is evacuated by operating a vacuum pump 5, argon is sealed from a rare gas sealing section 6 into this chamber. Sputtering by a high-frequency glow discharge system is first executed by operating a high-frequency glow discharge device 7 while the internal pressure of the sputtering chamber 4 is regulated to 2×10<-3> Torr. In succession, sputtering by a direct glow discharge system is executed by operating a direct glow discharge device 8.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a plastic substrate having a conductive layer by sputtering a metal on a non-conductive plastic film.

[0002]

2. Description of the Related Art A technique for forming a conductive metal or metal oxide film on a non-conductive plastic film is known, and a plastic substrate manufactured in this manner is
It is used as a material for various electronic components including touch panels. As a method of forming this conductive layer, a method of sputtering or vapor depositing a metal (metal oxide) is used.

In sputtering, a target object such as a metal or a metal oxide is hit with ions accelerated by electric discharge in a rare gas to fly off particles of the target object, which are then deposited on a substrate (plastic film). Compared to the vapor deposition method, etc., the adhesion between the formed target object film and the substrate is better, and a wide range of metals and metal oxides can be used as the target object. It is being used frequently, but with the recent increase in demand for liquid crystal panels and touch panels, the frequency of its use is increasing.

There are a direct current glow discharge method and a high frequency glow discharge method for discharge during sputtering, which are used depending on the characteristics of each, but in the production of conductive plastic substrates, the equipment is relatively inexpensive and sputtering is performed. A fast direct current glow discharge method is often used.

[0005]

However, in the field where the metal is sputtered on the plastic film to manufacture the plastic substrate having the conductive layer, as described above,
There is a problem that the manufactured plastic substrate is curled, and it is inconvenient to carry out the next operation using the plastic substrate. For example, when a plastic substrate is cut into a predetermined size or is stuck together, if the film is curled, the workability thereof becomes extremely poor. In particular, when metal is sputtered on a thin plastic film, the curl generated in the film is large and the problem is remarkable.

In order to reduce such curl, it is conceivable to take measures to reduce the thickness of the conductive layer formed on the plastic film. However, if the conductive layer is thinly formed, new problems such as loss of conductivity, occurrence of pinholes in the conductive layer due to dust, etc., and deterioration of the moisture-proof performance of the conductive layer occur, and therefore it is an excellent solution. It is not possible.

In view of the above problems, the present invention provides a method of manufacturing a plastic substrate having a conductive layer capable of reducing curl generated in the plastic substrate while ensuring conductivity and moistureproof performance. It is intended.

[0008]

In order to achieve the above object, the invention according to claim 1 provides a plastic substrate in which a conductive layer is formed on a non-conductive plastic film by sputtering a metal by discharge in a rare gas. A manufacturing method, the first sputtering step of performing sputtering under the condition of forming a conductive layer so that the plastic film is curled in a direction in which the conductive layer side is on the outside, and a plastic film in which the conductive layer side is inward. A second sputtering step in which sputtering is performed under the condition of forming a conductive layer that curls.

Further, in the invention described in claim 2, in contrast to the invention described in claim 1, in the first sputtering step, sputtering is performed by high frequency glow discharge,
The second sputtering step is characterized in that sputtering is performed by direct current glow discharge. Further, the invention according to claim 3 is different from the invention according to claim 1, in which the metal is nickel or tantalum, and in the first sputtering step, a rare operating pressure lower than a predetermined pressure is adjusted. Sputtering in gas, second
The sputtering step is characterized by performing sputtering in a rare gas adjusted to a high operating pressure higher than a predetermined pressure.

[0010]

The present inventors, while conducting research on a method for producing a plastic substrate having a conductive layer by sputtering, tend to curl a plastic substrate produced by sputtering a metal, but It was discovered that the plastic substrate produced by sputtering does not curl so much and that the direction and degree of curl of the plastic substrate produced by sputtering metal depend on the conditions during sputtering.

That is, for many metals such as chromium and titanium, when the sputtering is performed by the direct current glow discharge method, the curl (hereinafter
It has been found that a tendency to curl with the conductive layer side facing inward (hereinafter, referred to as incurl) is obtained by performing sputtering by the high frequency glow discharge method.

Further, for nickel and tantalum, the curling direction changes depending on whether the operating pressure during sputtering is higher or lower than a predetermined pressure of about 4 to 5 × 10 ⁻³ Torr, regardless of the glow discharge method. When the sputtering is performed in a rare gas adjusted to a low operating pressure lower than a predetermined pressure, the curl becomes outcurl, and when the sputtering is performed in a rare gas adjusted to a high operating pressure higher than the predetermined pressure, the curl tends to incur. all right.

Although the details of the reason why the direction and degree of curl depend on the sputtering conditions are not known yet, the crystal structure of the metal formed on the plastic film depends on the sputtering conditions. Difference or the difference in the spacing between the formed metal crystal particles,
It is presumed that there are cases where the conductive layer stretches the plastic film to cause out curl, and where the conductive layer contracts the plastic film to cause in curl.

The inventors of the present invention focused on such a phenomenon, and by combining the sputtering under the condition that the formed conductive layers curl in opposite directions at the time of sputtering, a plastic substrate is formed. The inventors have found that curl that occurs can be reduced, and arrived at the present invention. According to the invention of claim 1,
The conductive layer formed by the first sputtering step attempts to outcurl the plastic film,
The conductive layer formed by the second sputtering step tends to incur the plastic film.

Then, the effects of the conductive layers that try to curl in opposite directions are offset, and the curl of the plastic substrate is reduced. Further, the conductive layers formed in the first sputtering step and the second sputtering step are stacked, and the total thickness of the conductive layers is the sum of the thicknesses of the conductive layers.

Therefore, by appropriately combining the number of times the first sputtering step is performed and the number of times the second sputtering step is performed, the thickness of the conductive layer can be freely adjusted and curl can be reduced.
According to the second aspect of the invention, the conductive layer formed by performing the sputtering by the high frequency glow discharge in the first sputtering step tends to outcurl the plastic film.

On the other hand, in the second sputtering step,
The conductive layer formed by sputtering by direct current glow discharge tends to incur the plastic film. Further, according to the invention of claim 3, in the first sputtering step, the conductive layer of nickel or tantalum formed by sputtering in a rare gas adjusted to a low operating pressure lower than a predetermined pressure is formed. , Try to outcurl the plastic film.

On the other hand, in the second sputtering step,
The conductive layer of nickel or tantalum formed by sputtering in a rare gas adjusted to a high operating pressure higher than a predetermined pressure tends to incur the plastic film.

[0019]

EXAMPLES Examples of the method for producing a plastic substrate having a conductive layer according to the present invention will be specifically described below. (Embodiment 1) FIG. 1 is a schematic configuration diagram of a sputtering apparatus used in this embodiment. As shown in the figure, the sputtering apparatus 1 includes a sputtering chamber 4 including a substrate holder 2 for mounting a substrate 11 and a target electrode 3 for mounting a target object 12, and a vacuum capable of exhausting the sputtering chamber 4 to a high vacuum. A high-frequency glow in which a high-frequency voltage is applied between a pump 5, a rare-gas filling portion 6 capable of filling a rare gas at a desired pressure in a sputtering tank 4, a base 11 and a target object 12 to perform high-frequency glow discharge. Discharge device 7, base 11 and target object 1
It is composed of a DC glow discharge device 8 for applying a DC voltage between the two and DC glow discharge.

The substrate 11 used was a transparent polyphenylsulfite (PPS) film having a thickness of 3.5 μm and a size of 10 mm × 100 mm, which was surface-treated (washed with a solvent or the like). Since the base 11 of this film is extremely thin and difficult to handle as it is, the support film 13 for supporting the film was first attached so as to be easily peeled off, and then set on the base holder 2. As the support film 13, a polyethylene terephthalate (PET) film having a thickness of 50 μm was used. A chromium (Cr) plate was used as the target object 12 and was set on the target electrode 3.

Then, the vacuum pump 5 is operated to evacuate the sputtering tank 4, and argon is sealed from the rare gas sealing portion 6 so that the internal pressure in the sputtering tank 4 becomes 2 × 10.
While adjusting to ^-3 Torr, first, the high frequency glow discharge device 7 was operated to perform sputtering by the high frequency glow discharge system, and then the direct current glow discharge device 8 was operated to perform sputtering by the direct current glow discharge system.

The high-frequency glow discharge was discharged with an applied power of 2 kw for 162 seconds, and the direct current glow discharge was discharged with an applied power of 1 kw for 162 seconds. After the completion of sputtering, the substrate 11 was taken out of the sputtering tank 4 and the support film 13 was peeled off to manufacture a plastic substrate with a conductive layer. Then, with respect to the manufactured plastic substrate with a conductive layer, the thickness of the metal film to be the conductive layer was measured, and the state of the metal film was also examined. Further, the curl length measuring device 2 shown in FIG.
0 was used to measure the curl length.

The curl length measuring device 20 is composed of a vertically standing stainless plate 21 having a height of 130 mm and a fixing table 22 for supporting the lower end of the plate 21. To measure the curl length, one end of the plastic substrate with a conductive layer is attached to the upper end of the stainless plate 21 of the curl length measuring device 20 with a double-sided tape, and this is hung. At this time,
The plastic substrate with a conductive layer is attached so that the outer surface of the curl faces the stainless steel plate 21. In this state, the distance between the lower end of the plastic substrate and the stainless steel plate 21 is measured, and this is taken as the curl length. The results of these measurements are as shown in Table 1 below.

[0024]

[Table 1] The state of the metal film was extremely smooth, and pinholes due to dust or the like were not observed at all. Further, although some curl has occurred in the plastic substrate with a conductive layer, it has been confirmed that such a curl has no problem in practical use even when used as an electric circuit member of a head of an inkjet printer.

(Embodiment 2) The manufacturing method of the plastic substrate with the conductive layer of this embodiment is the same as that of the embodiment 1, except that the substrate 11 has a thickness of 12.5 μ instead of the PPS film.
m polyimide film (manufactured by Toray DuPont Co., Ltd., trade name: Kapton 50H) and that the order of the high frequency glow discharge and the direct current glow discharge at the time of sputtering was exchanged, that is, the direct current glow discharge device at the time of sputtering. 8 is operated to perform direct current glow discharge, and then the high frequency glow discharge device 7 is operated to perform high frequency glow discharge.

With respect to the manufactured plastic substrate with a conductive layer, the thickness of the metal film, the state of the metal film, the curl length, etc. were checked in the same manner as in Example 1. The measurement results are shown in Table 1.
The state of the metal film was extremely smooth, and no pinhole due to dust was observed. (Example 3) The method for manufacturing the plastic substrate with a conductive layer of this example is the same as that of Example 1, except that a titanium (Ti) plate is used as the target object 12 instead of a chrome plate, and during sputtering. The order of the high frequency glow discharge and the direct current glow discharge is reversed, and the direct current glow discharge device 8 is first operated to perform direct current glow discharge, and then the high frequency glow discharge device 7 is operated to perform high frequency glow discharge. There is.

With respect to the manufactured plastic substrate with a conductive layer, the film thickness of the metal film, the state of the metal film, the curl length, etc. were checked in the same manner as in Example 1. The measurement results are shown in Table 1.
The state of the metal film was extremely smooth, and no pinhole due to dust was observed.
In this example, the substrate 11 was once taken out and the curl state was checked after the completion of the sputtering by the DC glow discharge. As a result, an incurl having a curl length of 27 mm was observed as shown in parentheses in Table 1.

(Comparative Example 1) A plastic substrate with a conductive layer was manufactured in the same manner as in Example 1, but here, it was manufactured by performing only DC glow discharge type sputtering or high frequency glow discharge type sputtering. . Then, with respect to the manufactured plastic substrate with a conductive layer, the film thickness of the metal film, the state of the metal film, the curl length and the like were checked in the same manner as in Example 1. The measurement results are shown in Table 1. In addition, pinholes that were probably due to dust were observed in the metal film.

(Comparative Example 2) A plastic substrate with a conductive layer was manufactured in the same manner as in Example 2, but here, it was manufactured by performing only the sputtering by the direct current glow discharge method or only the sputtering by the high frequency glow discharge method. . Then, with respect to the manufactured plastic substrate with a conductive layer, the film thickness of the metal film, the state of the metal film, the curl length and the like were checked in the same manner as in Example 1. The measurement results are shown in Table 1. In addition, pinholes that were probably due to dust were observed in the metal film.

(Embodiment 4) In the method for manufacturing a plastic substrate with a conductive layer according to this embodiment, the sputtering apparatus 1 is used, and the substrate 11 has a thickness of 3.5 μm and a size of 10 mm ×.
As in Example 1, a 100 mm transparent PPS film was used to perform sputtering by glow discharge while enclosing argon under reduced pressure, but a nickel (Ni) plate was used as the target object 12, and a high frequency glow was used. The difference is that only the discharge method is used, and sputtering is performed by combining two operating pressures, a low operating pressure and a high operating pressure.

That is, in this embodiment, at the time of sputtering,
First, the internal pressure of the sputtering tank 4 is adjusted to 2 × 10 ⁻³ Torr to operate the high frequency glow discharge device 7, and then the internal pressure of the sputtering tank 4 is adjusted to 6 × 10 ⁻³ Torr to operate the high frequency glow discharge device 7. (Applied power is 2 kW, glow discharge time is 162 seconds each). And for the manufactured plastic substrate with a conductive layer,
In the same manner as in Example 1, the thickness of the metal film, the state of the metal film, the curl length, etc. were checked. The measurement results are shown in Table 2 below.

[0032]

[Table 2] The state of the metal film was extremely smooth, and pinholes due to dust or the like were not observed at all. Further, the curl of the plastic substrate with the conductive layer was small and was not a problem in practical use. (Example 5) The manufacturing method of the plastic substrate with a conductive layer of this example is the same as that of Example 4, except that the substrate 11 is replaced with a PPS film and a polyimide film having a thickness of 12.5 μm (manufactured by Toray DuPont) , Product name: Kapton 5
0H), a tantalum (Ta) plate was used as the target object 12 instead of a nickel plate, and a DC glow discharge method was used instead of the high frequency glow discharge method at the time of sputtering to obtain a low operating pressure and high operation. At the point where the order of pressure is changed, that is, at the time of sputtering, first, the internal pressure of the sputtering tank 4 is adjusted to a high operating pressure (6 × 10 ⁻³ Torr) to operate the DC glow discharge device 8, and then the sputtering tank 4 is operated. Low internal pressure (2 × 10 ^-3 Tor)
The difference is that the DC glow discharge device 8 is operated after adjusting to r).

Then, with respect to the manufactured plastic substrate with a conductive layer, the film thickness of the metal film, the state of the metal film, the curl length and the like were checked in the same manner as in Example 4. Table 2 shows the measurement results
Shown in The state of the metal film was extremely smooth, and no pinholes due to dust were observed. (Comparative Example 3) A plastic substrate with a conductive layer was produced in the same manner as in Example 4, except that a low operating pressure (2 x 10 ^-3 T) was used.
or high frequency glow discharge type sputtering at orr) or high frequency glow discharge type sputtering at high operating pressure (6 × 10 ⁻³ Torr).

Then, with respect to the manufactured plastic substrate with a conductive layer, the film thickness of the metal film, the state of the metal film, the curl length and the like were checked in the same manner as in Example 4. The measurement results are shown in Table 2. (Comparative Example 4) A plastic substrate with a conductive layer was manufactured in the same manner as in Example 4, but here, the value of the low operating pressure was 2 x.
The 0.7 × 10 ^-3 Torr in place of 10 ^-3 Torr,
Alternatively, as the value of the high operating pressure, 9.5 × 10 ^-3 Torr was used instead of 6 × 10 ^-3 Torr.

Then, with respect to the manufactured plastic substrate with a conductive layer, the film thickness of the metal film, the state of the metal film, the curl length and the like were checked in the same manner as in Example 4. The measurement results are shown in Table 4. [Discussion] From the measurement results and the like of the examples and comparative examples as described above, the following can be considered.

From the curl directions of Comparative Examples 1 and 2 in Table 1, it is found that chromium and titanium tend to cause incurl in the case of direct current glow discharge and outcurl in the case of high frequency glow discharge. Further, from the curl direction of Comparative Example 3 in Table 2, in the case of nickel,
It can be seen that a low operating pressure of 2 × 10 ⁻³ tends to cause outcurl, and a high operating pressure of 6 × 10 ⁻³ tends to cause incurl.

Further, in Table 1, the curl lengths of Examples 1 to 3 are all significantly smaller than those of Comparative Examples 1 and 2. From this, it is possible to reduce the curl length by combining the direct current glow discharge and the high frequency glow discharge in both cases of chromium and titanium.
Further, it can be seen that either the direct current glow discharge or the high frequency glow discharge may be performed first.

Further, in Table 2, the curl length of Example 4 is greatly reduced as compared with the curl length of Comparative Example 3. In addition, since the small curl length is obtained also in Example 5, it is understood that the curl length can be reduced by combining sputtering of low operating pressure and high operating pressure for nickel and tantalum. Here, it is understood that the effect is obtained in both cases of the DC glow discharge and the high frequency glow discharge, and that the order of the low operating pressure and the high operating pressure may come first. However, from the viewpoint of operation, it is considered that the operability is better when the low operating pressure is applied first.

Further, in Table 2, the curl length is larger in Comparative Example 4 than in Example 4, but this is performed by combining a low operating pressure and a high operating pressure as in Example 4. In this case, the operating pressure range is 1-9 × 10 ^-3 T
Perform in the range of orr, that is, 1 as the value of low operating pressure
Range to 4 × 10 ^-3 Torr are suitable, the range of 5 to 9 × 10 ^-3 Torr as the value of the high operating pressure suggests that it is appropriate.

Further, in Tables 1 and 2, the film thickness of the metal film is 0.1 μm in both cases of single discharge and 0.2 μm in case of double discharge. Is proportional to. Although the embodiments of the present invention have been described above, the present invention is not limited to the contents described in the above embodiments.

For example, aluminum, palladium, gold,
Similar to Comparative Examples 1 and 2, metals such as silver, copper, and platinum show a tendency of incurl in the case of DC glow discharge and outcurl in the case of high-frequency glow discharge. It can be carried out in the same manner as described above. However, in the case of chromium or titanium, curling is particularly likely to occur, and therefore the curl reducing effect according to the present invention is remarkable, but in the case of other metals, the effect is not so remarkable as that of chromium or titanium.

Further, in the above-mentioned first to third embodiments, the spa
The internal pressure in the tattering tank 4 is 2 × 10 ^-3Adjust to Torr
The general operating pressure was 10^-2-10^-FourTo Torr
Then, it can be implemented in the same manner. In addition, the above
In Examples 1-3, high frequency glow discharge and direct current glow discharge
In each of Examples 2 to 5 in which the electric power is applied once,
An example has been shown in which the discharge is performed once for each of the operating pressure and the high operating pressure.
However, when forming a thicker metal film, increase the number of discharges.
Repeatedly, the thickness of about 0.5μm
The metal film up to can be easily formed.

The thickness of the plastic film which can be generally used as the substrate 11 of Examples 1 to 5 is about 250 μm or less, and the thickness is 1 to 100 μm.
It is considered that the curl reducing effect is remarkable in a thin and flexible plastic film (especially about 1.5 to 50 μm). The material of the plastic film is preferably one having excellent heat resistance and dimensional stability. For example, polypropylene, polyethylene phthalate, polyamide (aromatic or aliphatic), polycarbonate, polyether sulfone, polyarylate, polyether ketone,
Examples thereof include polyparaxylylene, polyphenene sulfide, polyparabanic acid, thermoplastic polyimide, thermosetting polyimide, and thermosetting polyamide-imide. Among them, polyethylene phthalate, polyether sulfone, polyether ketone, polyarylate, polyimide Is a preferable material because it has excellent heat resistance and dimensional stability, and a thin film can be obtained.

These plastic films may be used as they are without treatment, but they may be treated by a physical method (removal of dust, etc.),
It is desirable to perform surface treatment by a physicochemical method (cleaning with a solvent, water, etc., corona discharge) or a chemical method (surface oxidation, surface roughening with a chemical). Also,
In the above-mentioned Examples 1 to 5, an example in which argon is used as the rare gas has been shown, but krypton, helium, or the like may be used in the same manner as above.

Further, in the above-mentioned Examples 1 to 5, the glow discharge time for one time was set to 162 seconds, but this glow discharge time was determined by experimenting with the required thickness of the metal film, the magnitude of the applied power, It is preferable to set an appropriate value within a range of about 1 to 3 minutes depending on the degree of curling. Further, the discharge time of each time when the glow discharge is repeated may be different from each other.

In the first to fifth embodiments, the applied power of the high frequency glow discharge is set to 2 kw and the applied power of the direct current glow discharge is set to 1 kw. About 3 kW (0.5 to 2 kW is efficient), and about 0.2 to 10 kW (0.5 to 5 kW is efficient), which is the applied power of general DC glow discharge.
Then, it can be implemented similarly.

[0047]

According to the method of manufacturing a plastic substrate having a conductive layer of the present invention, a low operating pressure and a high operating pressure can be achieved by combining high frequency glow discharge and direct current glow discharge during sputtering. By combining them, it is possible to reduce the curl of the plastic substrate while ensuring the performance of the formed conductive layer (that is, conductivity and moisture impermeable).

By reducing the curl of the plastic substrate, the workability in carrying out the next step using the plastic substrate is improved. In particular, since the curl reduction effect is remarkable when a thin plastic substrate is manufactured, it has a great practical effect in a field in which future demand is expected, such as a plastic substrate used for an electric circuit member of an inkjet printer head.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a sputtering apparatus according to an embodiment of the present invention.

FIG. 2 is a perspective view of a curl length measuring device according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sputtering apparatus 4 Sputtering tank 7 High frequency glow discharge device 8 DC glow discharge device 11 Base 12 Target object

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location H01B 13/00 503 H01B 13/00 503A // H01B 5/14 5/14 Z (72) Inventor Kinkai Saikai 163 Morikawara-cho, Moriyama-shi, Shiga Gunge Co., Ltd. Shiga Research Institute

Claims (3)

[Claims] 1. A method of manufacturing a plastic substrate in which a conductive layer is formed on a non-conductive plastic film by sputtering a metal in a rare gas by electric discharge, wherein the plastic film is curled so that the conductive layer side faces outward. The first sputtering step in which the conductive layer is formed so as to form a conductive layer, and the sputtering is performed under the condition in which the conductive layer is formed so as to curl the plastic film in such a manner that the conductive layer side faces inward. A method of manufacturing a plastic substrate having a conductive layer, comprising: a second sputtering step. 2. The conductive layer according to claim 1, wherein in the first sputtering step, sputtering is performed by high frequency glow discharge, and in the second sputtering step, sputtering is performed by direct current glow discharge. For manufacturing a finished plastic substrate. 3. The method for manufacturing a conductive plastic substrate according to claim 1, wherein the metal is nickel or tantalum, and in the first sputtering step, a rare operating pressure lower than a predetermined pressure is adjusted. The plastic having a conductive layer according to claim 1, wherein the sputtering is performed in a gas, and in the second sputtering step, the sputtering is performed in a rare gas whose operating pressure is higher than the predetermined pressure. Substrate manufacturing method.