1. Technical Field
The present invention relates to a heat retainer/heat generator and a method of manufacturing same, and more particularly, to a plane heating film for use in an integrated gas supply system for supplying a special gas for semiconductor manufacturing, and a method of manufacturing same.
2. Background Art
Generally, a special gas for semiconductor manufacturing introduced from a gas intake port 1 is controlled in volume through a gas flow path 2 of an integrated gas supply system (ISG), and delivered to a semiconductor manufacturing apparatus (not shown). The integrated gas supply system comprises a variety of gas flow control devices 5, including a pressure adjuster, a filter, a pressure sensor, a flow meter, and the like, carried on respective integration blocks (carriers) 3 heated by an integration block heat retainer/heat generator 7, through a plane heating film 4. The gas introduced from the gas intake port 1 at a high pressure of approximately 1 MPa and at high temperatures, flows through the variety of gas flow control devices 5 and the gas flow path 2 routed through the integration blocks 3 corresponding thereto, and is delivered from a gas discharge port 6 into the semiconductor manufacturing apparatus as a gas flow.
The gas flow control device 5 is fixed on the integration block 3 through the plane heating film 4 by a mounting flange 20. A gas flow 28 is introduced from a gas introduction port 21, and discharged from a gas discharge port 22 through the gas flow path 2. Assuming, for example, that the gas flow control device 5 is a pressure measuring device, a pressure sensor 23 is disposed on the gas flow path 2.
The gas flow 28 introduced at high pressure and high temperature gradually reduces its flow rate along bent portions of the gas flow path 2, and collides with the wall of the gas flow path 2. This collision causes a rapid attenuation of flow energy, resulting in crystallization of the gas to produce a deposit 24. This deposit 24 is known to be impediment to the gas flow 28.
To prevent such an impediment, conventionally, the integrated gas flow system is entirely heated by the integration block heat retainer/heat generator 7, and the variety of gas flow control devices 5 are respectively heated by the plane heating film 4, thereby preventing the crystallization of the deposit within the gas flow path 2. In this event, it is important to evenly and efficiently heat or retain the heat of the respective gas introduction/discharge ports of the variety of gas flow control devices 5.
Conventionally, the plane heating film 4 is fixed on the integration block 3 by the mounting flange 20 in order to heat or retain the heat of the respective gas introduction/discharge ports of the variety of gas flow control devices 5.
The plane heating film 4 comprises an electrically conductive section (heat generating section) and an insulating protection film 33. The electrically conductive section (heat generating section) comprises a metal resistive wire 31 which is made of a metal foil of SUS or the like patterned by etching or the like into fine meanders, and electrodes 32 formed at both ends of the metal resistive wire 31. The insulating protection film 33 is made of a heat-resistive resin film such as polyimide, which is bonded to the electrically conductive section with pressure on both sides thereof, and then patterned into an appropriate shape. The plane heating film 4 also comprises two gas supply ports (with gaskets) 34 for introducing and discharging the gas, and openings 35 at four corners thereof for receiving fixing screws in conformity to the shape of the mounting flange 20.
According to the conventional plane heating film 4, electric power is supplied between the electrodes 32 such that the plane heating film 4 takes advantage of a resulting heat generating effect of the metal resistive wire 31.
However, the conventional plane heating film 4, due to the employment of the metal resistive wire 31 for the electrically conductive section, exhibits a low resistance value per unit length, and accordingly requires a significant amount of electric power in order to generate heat needed for the purpose. Further, due to the employment of the fine metal resistive wire 31, the plane heating film 4 is vulnerable to bending stress, and exhibits a high resistance value in curved portions of the metal resistive wire 31 in particular. Thus, the conventional plane heating film 4 tends to exhibit locally higher temperatures caused by additional heat generated by a current which can concentrate in the curved portions of the metal resistive wire 31, and has the disadvantage of susceptibility to wire break. In the conventional plane heating film 4, the metal resistive wire, if broken, cannot be repaired, and it is extremely difficult to replace the failed plane heating film 4 with a normal one due to the structure of the gas flow control device 5.
To solve the disadvantage of the conventional plane heating film, it is an object of the present invention to provide a novel heat retainer/heat generator plate using carbon-nano-tube (CNT) paper, particularly, a plane heating film suitable for use in an integrated gas supply system for a special gas intended for semiconductor manufacturing. It is another object of the invention to provide a method of manufacturing the plane heating film.
To achieve the above object, the present invention provides a plane heating film using carbon nanotubes, particularly, a plane heating film suitable for use in an integrated gas supply system for a special gas intended for semiconductor manufacturing. The plane heating film comprises a piece of electrically conductive paper produced by mixing carbon nanotubes with pulp fiber, and patterning the mixture into a sheet, electrodes disposed in an end area of the electrically conductive paper for supplying electric power thereto, and a heat-resistive insulating film for laminating both sides of the electrically conductive paper.
The present invention also provides a method of manufacturing a plane heating film, which comprises the steps of patterning a piece of electrically conductive paper in conformity to the shape of the plane heating film, where the electrically conductive film is created by mixing carbon nanotubes with pulp fiber, and processing the mixture into a sheet; adhering a copper-foil electrode cut into the shape of electrode and copper-foil power supply electrodes for supplying power to the copper-foil electrode on the periphery and an end area of the electrically conductive paper; laminating both sides of the patterned electrically conductive paper with an insulating heat-resistive resin film, where the insulating heat-resistive resin film is formed by coating a high-temperature soluble polyamide resin on a polyimide film; and punching the laminated electrically conductive paper into a desired shape.
The essence of the present invention lies in a novel heat generating plate which can solve the disadvantage of the conventional plane heating film by employing carbon nanotube (CNT) paper.
A carbon nanotube is generally formed by wrapping up a sheet of graphite, and has a cylindrical shape, known as a carbon material having a diameter of several nanometers and a length of several microns. This material is regarded as an ideal one-dimensional substance because it exhibits the ratio of the length to the diameter equal to or more than 1,000. Further, this material can provide a current density larger than electrically conductive metal materials by one or more orders of magnitude.
When such carbon nanotubes are mixed with pulp fiber, and the resulting mixture is processed into a sheet, electrically conductive paper can be manufactured with good binding with the pulp fiber. When this electrically conductive paper is applied with a current, an ideal flat temperature distribution can be demonstrated as a heat retainer/heat generator.
Such electrically conductive paper exhibits electrical conductivity while having a certain electric resistance. Thus, when electrodes are formed in an end area of the electrically conductive paper and are applied with a voltage, the electrically conductive paper generates heat in accordance with the electric resistance thereof, thus acting as a laminar heat generator. This laminar heat generator provides uniform heat conduction over its entirety by virtue of excellent electric conductivity and thermal conductivity of carbon nanotubes. Moreover, this laminar heat generator serves as a material which excels in mechanical tensile strength and breaking strength with a complement in strength of the pulp fiber with carbon nanotubes entangled in a complicated manner. This electrically conductive paper provides the following benefits when it is applied to a plane heating film.
1. Reduction in distortions of heat generator material due to thermal expansion, and improved temperature characteristics.
2. High heat generating efficiency, and low power consumption.
3. Easy and safe temperature control.
4. Higher durability.
5. Free of wire break, as found in the conventional plane heating film including a metal resistive wire.
As described above, the plane heating film 50 comprises a piece of electrically conductive paper 51 created by mixing carbon nanotubes with pulp fiber, processing the resulting mixture into a sheet, and sandwiching the sheet with insulating films 52. Electrodes 53 are provided in an end area of the electrically conductive paper 51. The plane heating film 50 includes two gas supply ports (with gaskets) 54 for introducing and discharging a gas, and openings 55 at four corners thereof for receiving fixing screws in conformity to the shape of a mounting flange.
Now, a method of manufacturing the plane heating film according to the present invention will be described with reference to
First, in a first step of a plane heating film manufacturing process, a piece of raw electrically conductive paper 51, which forms part of a plane heating film, is cut in conformity to the shape of a mounting flange (not shown), gas supply ports 54, and cut-outs 60 for fixing screws, as shown in
Next, in a second step, as shown in a top plan view of
Next, in a third step, the electrically conductive paper 51 is laminated on both sides with insulating films, as shown in a top plan view of
Actually, a high-temperature soluble polyamide resin is coated on a polyimide film to form an insulating heat-resistive resin film 80. The electrically conductive paper 51, which has been formed with the copper-foil electrode 71 and copper-foil power supply electrodes 72, is sandwiched on both sides with the heat-resistive resin films 80. Then, the heat-resistant resin film 80 and electrically conductive paper 51 are bonded in vacuum through high-temperature, high-pressure pressing. In this way, by bonding the heat-resistive resin films 80 to the electrically conductive paper 51 in vacuum through high-temperature, high-pressure pressing to create an assembly, air remaining within the assembly is eliminated, thus enabling incombustibility to be maintained.
Finally, in a fourth step, the assembly laminated with the heat-resistive resin films 80 is punched into a desired shape with cut-out pressing or the like, as shown in a top plan view of
Two gas supply ports 54 for introducing and discharging a gas are preferably designed to allow metal gaskets to be mounted thereon for preventing a gas from leaking.
While the method of manufacturing a plane heating film according to the present invention has been described as a method of manufacturing a single plane heating film with reference to
A pair of electrically conductive paper 51A, 51B, each formed with the copper-foil electrode 71 and copper-foil power supply electrodes 72, as presented in the second step described above, are arranged to be opposite to each other. Then, a plurality of pairs of electrically conductive paper 51A, 51B (four pairs in
The plane heating film according to the present invention can be used alone, as a matter of course, but a plurality of the plane heating films can be connected in series in accordance with the size or thermal capacity of a particular gas flow control device which is to be heated or retained at a certain temperature.
The plane heating film of the present invention has been proven to provide significantly more energy saving effects than conventional plane heating films using metal (metal foil) resistive wires by experiments.
Specifically, a plane heating film using carbon nanotubes according to the present invention, and a conventional plane heating film using a metal (metal foil) resistive wire were created both as rectangular plane heating film having a thickness of 0.1 mm and one side of 25.5 mm. Then, power consumption per unit area, and temperature reached by generated heat were compared between the two plane heating films. The results are shown below.
Plane Heating Film Using Carbon Nanotubes According to the Present Invention:
Resistance: 65Ω;
Voltage and Current at which the temperature was reached to 80° C. by generated heat: 7.6 V, 0.1 A;
Power Consumption: 0.76 W
Resistance: 21Ω;
Voltage and Current at which the temperature was reached to 80° C. by generated heat: 5.1 V, 0.2 A;
Power Consumption: 1.20 W
From the foregoing results, according to the plane heating film of the present invention, approximately 30% of energy saving effect is recognized in the amount of heat generated on planar surface per unit area.
Number | Date | Country | Kind |
---|---|---|---|
2012/136693 | Jun 2012 | JP | national |