Atmospheric pressure plasma processing apparatus

Abstract

To provide an atmospheric pressure plasma processing method for performing sample processing in a short time while reducing the number of processing steps, and an atmospheric pressure plasma processing apparatus.SOLUTION: The present invention includes: a plasma generation apparatus 3 configured to supply a pressurized inert gas as a rotational flow from a gas introduction part 38 to an inner peripheral surface of a reaction tube body 31 and to generate plasma by supplying, to a high frequency resonance cavity 34, microwaves controlled to a predetermined amount of electric power; a reaction vessel 5 having a substantially cross shape; a sample movement mechanism 7 for enabling a sample SF to be movable relative to a plasma flow in the reaction vessel 5; and control means 9 for controlling a plasma generation state in accordance with a state of the sample, and performs plasma processing on a surface of the sample under atmospheric pressure.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention is capable of treating the surface of a sample by irradiating the sample with a plasma flow under atmospheric pressure. Rudai This invention relates to a atmospheric pressure plasma processing apparatus. [Background technology]

[0002] As is well known, polytetrafluoroethylene (PTFE) is a substance that can be said to be the ultimate material in many respects. In particular, it has been attracting attention recently as a circuit board material because it is not only heat-resistant but also has the lowest high-frequency loss factor. However, PTFE does not have sufficient hardness and strength, so it must be reinforced with epoxy resin or the like for use as a substrate.However, the difficulty of PTFE in adhering to the surfaces of other materials makes it difficult to use PTFE for circuit boards.

[0003] Therefore, a technique has been proposed to improve the adhesiveness of PTFE by irradiating it with low-temperature atmospheric pressure plasma using helium (He) (Non-Patent Document 1). Although this conventional technique (Non-Patent Document 1) has been successful in increasing adhesive strength to a certain extent, it still has the drawback of being weak in terms of mechanical strength. To overcome this drawback, a boron-hydrogen treatment method was proposed. Although this boron-hydrogen treatment method, when using an epoxy resin agent, was able to achieve higher adhesive strength than the He treatment method (Non-Patent Document 1), it had the drawback that the achieved strength was still not sufficient for industrial use.

[0004] In an attempt to overcome this drawback of insufficient mechanical strength, a thermally assisted plasma method (Non-Patent Document 2) was proposed, in which the sample is heated (to about 200°C) and irradiated with low-temperature atmospheric pressure He plasma. This thermally assisted plasma method (Non-Patent Document 2) can give the sample a relatively large increase in mechanical strength and also increase the adhesive strength of the sample.

[0005] Furthermore, Non-Patent Document 3 clarified more detailed plasma conditions, treatment time, sample heating temperature, and the chemical cause of improved adhesive strength due to heating for the thermally assisted plasma method, which were not clarified in Non-Patent Document 2. With this device, the sample is directly heated and plasma treated, and the layer called WBL, which is left on the sample surface due to the temperature increase, is removed, which has the effect of promoting the construction of a cross-linked structure on the sample surface. [Prior art documents] [Non-patent literature]

[0006] [Non-Patent Document 1] "Journal of Photopolymer Science and Technology" 2011 Vol. 24 No. 4 No. 441-445 [Non-patent document 2] Surface Technology, Vol. 67, No. 10, 2016, pp. 551-556 [Non-patent document 3] "Journal of Photopolymer Science and Technology" 2022 Vol. 35 No. 4 No. 299-302 Summary of the Invention [Problem to be solved by the invention]

[0007] However, conventional low-temperature He atmosphere pressure The thermally assisted plasma method using plasma can roughen the PTFE surface and increase adhesive strength, but the roughened surface also causes the following drawbacks. That is, when PTFE treated by the conventional thermally assisted plasma method is used on electronic substrates, the signal delay time deteriorates as the substrate surface roughness increases. Since the roughness of the PTFE surface is related to the plasma treatment time, long-term plasma treatment is not recommended.

[0008] On the other hand, in the treatment using this thermally assisted plasma method, a minimum treatment time of about 5 minutes is required regardless of the PTFE (sample) temperature, and since practical mechanical strength is not achieved within that time, it was not possible to shorten the treatment time.

[0009] As described above, conventional plasma processing techniques have the drawback of being unable to satisfy the contradictory requirements of shortening the processing time in order to reduce the roughness of the sample surface and lengthening the processing time in order to increase the mechanical strength of the sample. Furthermore, the conventional thermally assisted plasma method described above has the disadvantage of not being able to satisfy one of the industrial requirements for sample processing in the shortest possible time. Furthermore, according to the above-mentioned conventional techniques, it is necessary to preheat the sample to several hundred degrees, which is an inconvenience in that it does not satisfy the requirement to reduce the number of steps as much as possible, which is one of the performance requirements in industry.

[0010] The present invention overcomes the above-mentioned disadvantages of the prior art, and allows sample processing to be performed in a short time, while eliminating unnecessary processing steps and reducing the number of processing steps. Rudai To provide a atmospheric pressure plasma processing apparatus. [Means for solving the problem]

[0011] In order to solve the above problems, the present invention Rudai The atmospheric plasma processing apparatus employs the following means.

[0012] Claim 1 The atmospheric pressure plasma processing apparatus according to the present invention is an atmospheric pressure plasma processing apparatus which supplies a pressurized inert gas and a high frequency electric field into a reaction cylindrical body to generate plasma inside the reaction cylindrical body, and performs surface processing on a sample with the plasma flow blown out from the reaction cylindrical body, a gas inlet and a gas outlet are provided in the reaction tube; a high-frequency resonant cavity is provided so as to surround the outer periphery of the reaction cylindrical body; supplying a pressurized inert gas into the reaction tube from the gas inlet while rotating; a plasma generating device that supplies a high frequency wave to the high frequency resonant cavity to generate plasma within the reaction cylindrical body and blows out a plasma flow from a gas outlet of the reaction cylindrical body; a reaction vessel having a generally cross-shaped configuration, in which a gas inlet and a gas outlet are provided in a linear cylindrical shape, and a cylindrical sample insertion port is provided perpendicular to the gas inlet and the gas outlet, and the gas inlet is connected to a gas outlet port of the reaction cylindrical body; a sample moving mechanism that can be arranged in a direction of the sample insertion port of the reaction vessel, on which the sample can be detachably placed, and that can move the sample within the reaction vessel relatively to the blowing direction of the plasma flow blown out from the gas ejection part; a control means for detecting at least the temperature state of the sample in the reaction vessel and, based on the temperature state, adjusting the high frequency power so that the state of the plasma flow and the surface temperature of the sample are maintained in predetermined states; The sample is exposed to the plasma flow to cause a reaction with the plasma flow, thereby performing surface treatment on the sample.

[0013] Claim 2 In the atmospheric pressure plasma processing apparatus according to the present invention, 1 In the above, the pressurized inert gas is argon gas or a gas obtained by mixing argon gas and helium gas in a predetermined amount.

[0014] Claim 3 The atmospheric pressure plasma processing apparatus according to the present invention supplies argon gas or a gas obtained by mixing predetermined amounts of argon gas and helium gas, and microwaves into a reaction cylindrical body to generate plasma in the reaction cylindrical body, and performs surface treatment on a sample using a plasma flow blown out of the reaction cylindrical body, a plasma generating device comprising: a gas inlet and a gas outlet in the reaction cylinder; a cooling cylinder surrounding the outer periphery of the reaction cylinder; a high-frequency resonant cavity surrounding the outer periphery of the cooling cylinder; pressurized argon gas being supplied from the gas inlet into the reaction cylinder as a rotating flow; a cooling medium being passed through the cooling cylinder to cool the forward-movable reaction cylinder; microwaves of a predetermined amount of power being supplied to the high-frequency resonant cavity to bring the high-frequency resonant cavity into a resonant state, thereby generating plasma in the reaction cylinder and causing a plasma flow to be blown out from the gas outlet of the reaction cylinder; a reaction vessel having a substantially cross shape, in which a gas inlet and a gas outlet are linearly provided and an insertion port for a cylindrical sample is provided perpendicularly to the gas inlet and the gas outlet, and the gas inlet is connected to a gas outlet portion of the reaction cylindrical body; a sample moving mechanism that enables the sample to be moved within the reaction vessel relative to the direction in which the plasma flow is blown out from the gas outlet; a control means for detecting at least the temperature state of the sample in the reaction vessel and, based on the temperature state, adjusting the high frequency power so that the state of the plasma flow and the surface temperature of the sample are maintained in predetermined states; The sample is exposed to the plasma flow to react with the plasma flow, thereby performing surface treatment on the sample.

[0015] Claim 4 In the atmospheric pressure plasma processing apparatus according to claim 3 The control means is capable of adjusting the high frequency power so that the plasma flow reaches directly onto the surface of the sample.

[0016] Claim 5 In the atmospheric pressure plasma processing apparatus according to claim 3 In the present invention, the control means is capable of adjusting the high frequency power so that the temperature of the sample surface that the plasma flow reaches is maintained at around 200°C.

[0017] Claim 6 In the atmospheric pressure plasma processing apparatus according to the present invention,3 In the present invention, the control means is characterized in that it can set the microwave power value supplied to the high-frequency resonant cavity to the maximum value that allows the plasma flow to reach the sample surface directly and maintain the sample surface temperature at around 200°C. [Effects of the Invention]

[0018] According to the present invention, the plasma flow can be reliably delivered to the sample, the sample surface temperature can be maintained at a predetermined temperature, and the sample and the plasma flow can be moved relative to each other, which has the following effects: (1) It is possible to satisfy the contradictory requirements of shortening the processing time to reduce the roughness of the sample surface and lengthening the processing time to increase the strength of the sample. (2) It can satisfy one of the industrial requirements for sample processing in the shortest possible time. (3) It also satisfies the industrial requirement to minimize the number of processes. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a block diagram showing an atmospheric pressure plasma processing apparatus according to an embodiment of the present invention; [Figure 2] 1 is an explanatory diagram showing a main part of an atmospheric pressure plasma processing apparatus according to an embodiment of the present invention; [Figure 3] FIG. 10 is a characteristic diagram showing peel strength versus processing time of a sample processed by the atmospheric pressure plasma processing apparatus according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, the present invention will be described in detail with reference to the embodiment. Rudai The atmospheric pressure plasma processing apparatus will now be described.

[0021] Fig. 1 is an overall block diagram showing an atmospheric pressure plasma processing apparatus according to an embodiment of the present invention, and Fig. 2 is an explanatory diagram showing the main parts of the atmospheric pressure plasma processing apparatus. 1 and 2, an atmospheric pressure plasma processing apparatus 1 according to an embodiment of the present invention is broadly comprised of a plasma generating apparatus 3 that generates plasma and blows out the plasma, a reaction vessel 5 as a reaction field in which the plasma flow Pf from the plasma generating apparatus 3 is exposed to a PTFE sample SF to cause a reaction, a sample moving mechanism 7 that detachably positions the sample SF and can move the sample SF relative to the plasma flow Pf within the reaction vessel 5, and a control system 9 that detects the state of the plasma generated in the plasma generating apparatus 3 and the surface temperature of the sample SF and controls the plasma generation state of the plasma generating apparatus 3.

[0022] 1 and 2, the plasma generator 3 includes a reaction cylinder 31 made of quartz in a long cylindrical shape, a cooling cylinder 32 also made of quartz and integrally provided coaxially with the central axis of the reaction cylinder 31 so as to surround the outer periphery of the reaction cylinder 31, an electromagnetic shield 33 provided coaxially with the central axis of the reaction cylinder 31 so as to surround the outer periphery of the cooling cylinder 32, and a high-frequency resonant cavity 34 provided coaxially with the central axis of the reaction cylinder 31 so as to surround the outer periphery of the cooling cylinder 32. Microwaves μW are supplied to the high-frequency resonant cavity 34 via a circulator 36a, a power meter 36b, a waveguide 36c, and a three-stub tuner 36d.

[0023] 1 and 2, the reaction cylindrical body 31 is made of quartz and has a long cylindrical shape. This reaction cylindrical body 31 is provided with a gas inlet 37 at the center of the upper side in the figure, and gas inlets 38, 38 at the outer peripheral surface of the cylinder on the upper side in the figure. In addition, a gas outlet 39 is provided at the lower part of this reaction cylindrical body 31 in the figure. The gas introduction section 37 is configured so that a predetermined amount of carbon dioxide gas (CO2 gas) can be mixed and supplied via a mass flow controller (MFC) 40c, nitrogen gas (N2 gas) via an MFC 40n, and argon gas (Ar gas) via an MFC 40a.

[0024] The gas inlets 38 are configured to receive Ar gas via a mass flow controller (MFC) 41. The gas inlets 38 are arranged to face diagonally downward in the figure and are offset in the tangential direction of the outer periphery of the reaction cylindrical body 31, so that the Ar gas introduced from the gas inlets 38 rotates downward in the figure along the inner periphery of the reaction cylindrical body 31 and also applies a rotational force to the inert gas introduced from the gas inlet 37 as it descends. The plasma generated in the reaction cylindrical body 31 becomes a plasma flow Pf and is discharged from the gas outlet 39.

[0025] 1 and 2, the cooling cylinder 32 is made of quartz and is disposed coaxially around the central axis of the reaction cylinder 31 so as to surround the outer periphery of the reaction cylinder 31. The cooling cylinder 32 is provided with a cooling medium inlet 32n on the lower side of the figure and a cooling medium outlet 32t on the upper side of the figure. The cooling medium R enters the cooling cylinder 32 from the cooling medium inlet 32n, moves upward in the figure while cooling the reaction cylinder 31, and is discharged from the cooling medium outlet 32t.

[0026] The reaction vessel 5 is made of quartz and, as shown in Figures 1 and 2, is configured in a roughly cross shape with a vertical cylinder and a horizontal cylinder. The vertical cylinder is provided with a gas inlet 51 on the upper side in Figures 1 and 2 and a gas outlet 52 on the lower side in Figures 1 and 2. Insertion holes 53, 53 for the sample SF are provided on the left side of the horizontal cylinder in Figures 1 and 2 and on the right side in Figures 1 and 2. The diameter of the gas inlet 51 becomes thinner toward the top in Figures 1 and 2, and finally becomes the same as the inner diameter of the gas outlet part 39 of the reaction cylinder 31, and the gas inlet 51 is connected to the gas outlet part 39 in a bonded state. In the reaction vessel 5, the plasma flow Pf from the plasma generator 3 is directly exposed to the sample SF, and serves as a reaction field where the sample SF reacts with the plasma flow Pf.

[0027] The sample moving mechanism 7 is composed of a hollow aluminum (Al) drum tube 70, the diameter of which is set slightly smaller than the inner diameter of the insertion openings 53, 53 of the reaction vessel 5. The sample SF is wound around the hollow drum tube 70 at a predetermined position near the center in the longitudinal direction, and the hollow drum tube 70 is passed through the insertion openings 53, 53. The sample SF is positioned as shown in Figure 1 so that the plasma flow Pf can be sprayed onto it. A cooling medium r can be supplied from one side of the hollow drum tube 70 and discharged from the other side, allowing the hollow drum tube 70 to be cooled.

[0028] When the hollow drum tube 70 is positioned as described above, one end of the hollow drum tube 70 is rotatably fixed to a fixing portion 71, and the other end of the hollow drum tube 70 is fixed to a rotation shaft 72 of a motor M. As a result, the hollow drum tube 70 is rotated at a predetermined speed by the motor M, and the sample SF can be moved relative to the plasma flow Pf.

[0029] The control system 9 includes at least a sensor unit 91 provided at a predetermined position in the reaction cylinder 31 of the plasma generator 3, an optical fiber 92 for guiding detection light from the sensor unit 91, an optical sensor unit 93 arranged at a predetermined position in the reaction vessel 5 for measuring the surface temperature of the sample SF, an optical fiber 94 for guiding the detection light from the optical sensor unit 93, and a control device 95 including a spectroscope that can take in each of the detection lights from the optical fibers 92 and 94 and create a control command CS according to a predetermined algorithm based on the detection light and the output from the power meter 36c.

[0030] A control command CS from a control device 95 including a spectrometer is used to adjust the output power of the magnetron generator 35. The magnetron generator 35 adjusts the power value of the generated microwave μW based on the control command CS. The microwave μW whose power value has been controlled in this manner is supplied to the high frequency resonant cavity 34 via a circulator 36a, a power meter 36b, a waveguide 36c, and a three-stub tuner 36d. As a result, the plasma generated in the reaction tube 31 is controlled based on the control command CS.

[0031] According to the atmospheric pressure plasma processing apparatus 1 having such a configuration, the plasma processing of the PTFE sample SF is carried out as follows.

[0032] Predetermined amounts of CO gas, N gas, and Ar gas are mixed via a mass flow controller (MFC) 40c, MFC 40n, and MFC 40a, respectively, and are supplied into the reaction tube 31 from the gas inlet 37. The supply of these gases may be performed as needed, but is not essential.

[0033] Further, other Ar gas is supplied into the reaction cylindrical body 31 from the gas inlets 38, 38 via a mass flow controller (MFC) 41. The gas inlets 38, 38 are arranged so as to face diagonally downward from above in the figure and are shifted in the tangential direction of the outer periphery of the reaction cylindrical body 31, so that the Ar gas introduced from the gas inlets 38, 38 moves downward in the figure while rotating along the inner circumferential surface of the reaction cylindrical body 31.

[0034] In addition, when inert gases (CO2 gas, N2 gas, Ar gas) are supplied into the reaction vessel 5 from the gas inlet 37, the Ar gas that moves downward while rotating as described above also transmits a rotational force to these inert gases (CO2 gas, N2 gas, Ar gas) as it moves downward.

[0035] In this state, microwaves μW are supplied to the high frequency resonant cavity 34 from a magnetron generator 35 via a waveguide 36 .

[0036] As a result, high-temperature plasma with a gas temperature of approximately 3,000 to 4,000°C is generated inside the reaction cylinder 31. This plasma becomes a plasma flow Pf from the gas outlet 39 of the reaction cylinder 31 and is blown out into the reaction vessel 5 from the gas inlet 51. The high-temperature plasma generated inside the reaction cylinder 31 is gradually cooled by the cooling medium R flowing inside the cooling cylinder 32 provided on the outer periphery of the reaction cylinder 31 as it flows down along the gas flow, and finally flows out as a plasma flow Pf from the gas outlet 39. This achieves the process of blowing out a plasma flow from the gas outlet 39 of the reaction cylinder 31.

[0037] 1, a sample SF is wound around a predetermined position of the hollow drum tube 70. The hollow drum tube 70 is passed through the insertion openings 53, 53 of the reaction vessel 5, and the sample SF is set at the center of the reaction vessel 5 as shown in FIGS. In this state, the hollow drum tube 70 of the sample moving mechanism 7 is rotated at a predetermined speed, thereby moving the sample SF relative to the plasma flow Pf. This achieves a step of exposing the sample SF to the plasma flow Pf while moving the sample SF in a direction perpendicular to the blow-out direction of the plasma flow Pf. In addition, in this embodiment, in order to avoid an excessive rise in surface temperature due to direct contact of the plasma flow Pf with the surface of the sample SF, and to avoid time and spatial non-uniformity in exposure to the plasma flow Pf reaching the surface of the sample SF, the surface of the sample SF is moved at a relatively high speed.

[0038] Furthermore, in the above embodiment, the sample SF and the plasma flow Pf are moved relative to each other by rotating the hollow drum tube 70, but the key is that the sample SF and the plasma flow Pf move relative to each other. For example, the sample SF may be moved at a predetermined speed in the direction of the insertion openings 53, 53, i.e., in the horizontal direction shown in the figure, or the sample SF and the plasma flow Pf may be moved relative to each other by other moving methods.

[0039] Furthermore, the plasma generation state of the plasma generator 3 is controlled by a control system 9. Specifically, this is as follows: Detection light from a sensor unit 91 that detects the inside of the reaction cylinder 31 is supplied via an optical fiber 92 to a control unit 95 that includes a spectrometer, and detection light from an optical sensor unit 93 that detects the surface temperature of the sample SF is supplied via an optical fiber 94 to a control unit 95 that includes a spectrometer. The control unit 95 can generate a control command CS using a predetermined algorithm based on each detection light and the output value from the power meter 36b. Based on the control command CS from this control unit 95, the magnetron generator 35 controls the amount of microwave power (μW) that it generates.

[0040] This control command CS controls the amount of power of the microwaves μW generated by the magnetron generator 35, and the microwaves μW are supplied to the high frequency resonant cavity 34, thereby ensuring the following state. (a) The plasma flow Pf from the reaction cylinder 31 reaches directly onto the surface of the sample SF. (b) The surface temperature of the sample SF, which is directly hit by the plasma flow Pf, can be maintained at a predetermined temperature. (c) The discharge power value (power applied to the high frequency resonant cavity 34) required for high speed plasma processing can be supplied at the maximum value such that the above (a) and (b) are simultaneously satisfied.

[0041] The atmospheric pressure plasma processing apparatus according to the embodiment of the present invention, which operates in this manner, has the following advantages. (1) It is possible to satisfy the contradictory requirements of shortening the processing time to reduce the roughness of the sample surface and lengthening the processing time to increase the adhesive strength of the sample. (2) It can satisfy one of the industrial requirements for sample processing in the shortest possible time. (3) Furthermore, it can also satisfy one of the industrial requirements for reducing the number of processes as much as possible. [Example]

[0042] Next, an embodiment of the atmospheric pressure plasma processing apparatus according to the present invention will be described mainly with reference to Fig. 2. Note that, although specific dimensions are used in Fig. 2 for the description, the present invention is not limited to these dimensions, and it goes without saying that other dimensions may be used as long as the same operational effects are obtained.

[0043] In the plasma generator 3, a microwave μW of 2.45 [GHz] is supplied from a magnetron generator 35 to a high-frequency resonant cavity 34 provided on the outer periphery of a reaction cylindrical body 31. A reaction vessel 5 was placed at a position at a length La = 9.5 [cm] below the lower end of the high-frequency resonant cavity 34. This reaction vessel 5 is manufactured to the following dimensions. In the reaction vessel 5, the inner diameter D of the horizontal cylinder including one insertion port 53 and the other insertion port 53 is D = 24 [mmφ], and the length Lb of the horizontal cylinder is Lb = 50 [mm]. As already explained, the horizontal cylinder including these insertion ports 53, 53 and the vertical cylinder including the gas inlet port 51 and the gas outlet port 52 form the reaction vessel 5 in a substantially cross shape. In the sample moving mechanism 7, the total length Lc of the hollow drum tube 70 made of aluminum (Al) was set to Lc=160 [mm], and the outer diameter d thereof was set to d=20 [mmφ].

[0044] The sample SF is wound around the center of the hollow drum 70. The thickness of the sample SF is 0.5 mm, but the thickness of the sample SF is not limited to this. One end of the hollow drum 70 is inserted through the insertion opening 53 on the left side (one side) of the horizontal cylinder of the reaction vessel 5 in FIG. 2. Then, one end of the hollow drum 70 is extended out through the insertion opening 53 on the right side (the other side) of FIG. 2, and the sample SF wound around the center of the hollow drum 70 is finally set in the center of the reaction vessel 5 as shown in FIGS. 1 and 2. When set up in this manner, as shown in Figure 1, one end of the hollow drum tube 70 is rotatably fixed to a fixed part 71, and the other end of the hollow drum tube 70 is fixed to a rotating shaft 72 of a motor M, so that the hollow drum tube 70 rotates by the motor M, and the sample SF wrapped around the center of the hollow drum tube 70 can be moved.

[0045] After the sample SF is placed in the above-described state, plasma is generated in the reaction tube 31 of the plasma generator 3 and irradiated as a high-temperature plasma flow PF onto the sample SF in the reaction vessel 5, exposing the sample SF to the plasma flow PF. At this time, based on the control command CS of the control system 9, the plasma generator 3 is controlled so that the plasma flow Pf (microwave afterglow) reaches the surface of the sample SF directly, and so that the surface temperature of the sample SF that is reached by the plasma flow Pf becomes a surface temperature of around 200°C. These controls are performed based on the control command CS from the control system 9 to control the power applied to the high-frequency resonant cavity 34 so that the plasma flow Pf reaches the surface of the sample SF directly and the surface temperature of the sample SF reached by the plasma flow Pf becomes a surface temperature of around 200°C, i.e., so that two requirements are satisfied simultaneously.

[0046] P The plasma flow PF is allowed to freely flow out into the atmosphere from the gap between the insertion ports 53, 53 of the reaction vessel 5 and the hollow drum tube 70, or from the gas outlet port 52. Therefore, the processing portion (processing space) of the sample SF is a semi-free space blow-out type.

[0047] Furthermore, to avoid excessive surface temperature rise due to direct contact of the plasma flow Pf with the surface of the sample SF, and to limit the time the plasma flow Pf reaches the surface of the sample SF and to avoid spatial nonuniformity of the plasma flow Pf, the surface of the sample SF must be moved at a relatively high speed. For this reason, in this example, the hollow drum 70 was rotated at a speed of 6 rpm. This enabled the desired performance to be achieved. The reason for exposing the sample SF to the plasma while rotating it on the hollow drum 70 in this way is to suppress local temporal fluctuations in the exposure intensity on the surface of the sample SF due to temporal fluctuations in the emission distribution specific to atmospheric-pressure Ar plasma.

[0048] Regarding cooling of the hollow drum tube 70, it is conceivable to use forced circulation of water, air or other cooling medium, but it is also possible to use natural air cooling by opening the hollow interior of the hollow drum tube 70 to the atmosphere.

[0049] FIG. 3 is a characteristic diagram obtained by an example of the atmospheric pressure plasma processing apparatus according to the present invention, showing the relationship between peel strength and processing time under the conditions that showed the maximum peel strength.

[0050] The sample SF obtained by the plasma treatment according to the above embodiment will now be examined. The sample SF obtained by the plasma treatment was tested as follows. For the adhesive strength test, the adherend surface of the plasma-treated sample SF was adhered to a stainless steel plate using an epoxy adhesive, and after leaving it at room temperature for 24 hours, measurements were taken using a tensile strength tester (Minebea Corporation 88FD Model LTS) in a 180-degree peel test. Chemical observations of the surface of the measured sample SF were mainly carried out using ULVAC's PHI5000 Versa Probe and XPS, and a comprehensive surface chemical analysis was performed.

[0051] In the test results described above, the maximum value Max of the measured values ​​is shown by a solid line, and the average value Mean of the measured values ​​is shown by a dotted line in FIG. In this strength peel test, as shown in Figure 3, the peel strength was small when the treatment time was short, but the longer the treatment time, the greater the peel strength became, with the maximum peel strength reaching 2 kN / m after 42 seconds of treatment. -1 ], exceeding the highest value (1.2 [kN / m -1 ]) was obtained. Furthermore, as the treatment time was increased beyond the time at which the maximum peel strength was obtained (42 seconds treatment), the peel strength gradually decreased. This result shows that optimizing the treatment time is an important factor in obtaining the maximum peel strength.

[0052] From the above, it can be seen that in the embodiment of the atmospheric pressure plasma processing apparatus according to the present invention, the following conditions are suitable for surface processing of a PTFE sample using a plasma flow (microwave afterglow) using Ar gas to obtain optimal strength while preventing deterioration of high-frequency characteristics. (Condition 1) The plasma flow Pf (microwave afterglow) must reach the surface of the sample SF directly. (Condition 2) The surface temperature of the sample SF that is being reached by the plasma flow Pf must be controlled to around 200°C. (Condition 3) The discharge power value (power applied to the high-frequency resonant cavity 34) required for high-speed plasma processing must be set to the maximum value that satisfies both "Condition 1" and "Condition 2" simultaneously. (Condition 4) The surface of the sample SF must be moved at a relatively high speed to avoid excessive rise in surface temperature due to direct contact of the plasma flow Pf with the surface of the sample SF, and to avoid time and spatial non-uniformity in exposure of the plasma flow Pf reaching the surface of the sample SF.

[0053] Generally, when the peel strength is low, adhesive components and oxygen taken in from the air are detected on both peel interfaces. However, taking these conditions into consideration, in the case of the PTFE sample SF that was plasma-treated in the above example, no oxygen atoms taken in from the air were found on either the PTFE side or the adhesive side at the adhesive peel surface that showed the highest peel strength, and only fluorocarbon (CF2) bonds were observed, suggesting that cohesive failure had occurred deeper inside the PTFE.

[0054] In the above explanation, a configuration example was shown in which a small amount of different molecular gas (one or more of CO2 gas and N2 gas) can be added from the gas inlet 37 to the Ar gas flow supplied from the gas inlet 38 into the reaction tube 31. However, it was found that there is a high possibility that this will have an adverse effect on the adhesive strength, so it is preferable to have only Ar gas flow from the gas inlet 38. In addition, measurements using a surface roughness meter before and after treatment under the maximum peel strength conditions showed no significant change in roughness. , surface melting due to temperature rise, and etch pits formed due to contact with the plasma flow. No change is observed.

[0055] According to an embodiment of the atmospheric pressure plasma processing apparatus of the present invention, a PTFE sample processed by this apparatus was subjected to a pressure of 2 [kN / m -1 ] and the processing speed was able to be achieved in seconds, which has the following effects. (1) The roughness of the sample surface can be reduced, so the processing time can be shortened, and the strength of the sample can be increased in a short processing time. (2) It can satisfy one of the industrial requirements for sample processing in the shortest possible time. (3) Furthermore, since the sample can be heated and treated simultaneously, it satisfies one of the industrial requirements for reducing the number of steps as much as possible. [Explanation of symbols]

[0056] 1. Atmospheric pressure plasma treatment device 3. Plasma generator 5. Reaction vessel 7. Sample transfer mechanism 9 Control System 31 Reaction tube 32 Cooling cylinder 33 Electromagnetic Shielding 34 High Frequency Resonant Cavity 37 Gas inlet 38 Gas inlet 39 Gas outlet 51 Gas inlet 52 Gas outlet 53, 53 insertion port 70 Hollow Drum 91, 93 Sensor section 92, 94 Optical fiber 95 Control Device

Claims

1. a step of supplying a pressurized inert gas from the gas inlet into a reaction cylindrical body having a gas inlet and a gas outlet while rotating the gas, and supplying a high frequency wave to the reaction cylindrical body to generate plasma inside the reaction cylindrical body and blowing out a plasma flow from the gas outlet of the reaction cylindrical body; exposing the sample to the plasma flow while moving the sample relatively in a direction in which the plasma flow is blown out; a control step of adjusting the plasma generation state by controlling the high frequency power so that the plasma flow reaches the sample and the sample surface temperature is maintained at a predetermined temperature; This is an atmospheric pressure plasma processing method characterized by performing surface processing on a sample.

2. 1. An atmospheric pressure plasma processing apparatus that supplies a pressurized inert gas and a high-frequency electric field into a reaction cylindrical body to generate plasma inside the reaction cylindrical body, and performs surface processing on a sample with the plasma flow blown out of the reaction cylindrical body, a plasma generating device which provides a gas inlet and a gas outlet in the reaction cylindrical body, provides a high frequency resonant cavity so as to surround the outer periphery of the reaction cylindrical body, supplies a pressurized inert gas into the reaction cylindrical body from the gas inlet while rotating it, supplies a high frequency wave to the high frequency resonant cavity to generate plasma in the reaction cylindrical body, and causes a plasma flow to be blown out from the gas outlet of the reaction cylindrical body; a reaction vessel having a generally cross-shaped configuration, in which a gas inlet and a gas outlet are provided in a linear cylindrical shape, and a cylindrical sample insertion port is provided perpendicular to the gas inlet and the gas outlet, and the gas inlet is connected to a gas outlet port of the reaction cylindrical body; a sample moving mechanism that can be arranged in a direction of the sample insertion port of the reaction vessel, on which the sample can be detachably placed, and that can move the sample within the reaction vessel relatively to the blowing direction of the plasma flow blown out from the gas ejection part; a control means for detecting at least the temperature state of the sample in the reaction vessel and, based on the temperature state, adjusting the high frequency power so that the state of the plasma flow and the surface temperature of the sample are maintained in predetermined states; The atmospheric pressure plasma processing apparatus is characterized in that the sample is exposed to the plasma flow and reacted with the plasma flow to perform surface processing of the sample.

3. 3. The atmospheric pressure plasma processing apparatus according to claim 2, wherein the pressurized inert gas is argon gas or a gas obtained by mixing argon gas and helium gas in predetermined amounts.

4. An atmospheric pressure plasma processing apparatus that supplies argon gas or a gas mixture of argon gas and helium gas in a predetermined amount and microwaves into a reaction cylindrical body to generate plasma in the reaction cylindrical body, and performs surface processing of a sample with the plasma flow blown out of the reaction cylindrical body, a plasma generating device comprising: a gas inlet and a gas outlet in the reaction cylinder; a cooling cylinder surrounding the outer periphery of the reaction cylinder; a high-frequency resonant cavity surrounding the outer periphery of the cooling cylinder; pressurized argon gas being supplied from the gas inlet into the reaction cylinder as a rotating flow; a cooling medium being passed through the cooling cylinder to cool the reaction cylinder; microwaves of a predetermined amount of power being supplied to the high-frequency resonant cavity to bring the high-frequency resonant cavity into a resonant state, thereby generating plasma in the reaction cylinder and causing a plasma flow to be blown out from the gas outlet of the reaction cylinder; a reaction vessel having a substantially cross shape, in which a gas inlet and a gas outlet are linearly provided and an insertion port for a cylindrical sample is provided perpendicularly to the gas inlet and the gas outlet, and the gas inlet is connected to a gas outlet portion of the reaction cylindrical body; a sample moving mechanism that enables the sample to be moved within the reaction vessel relative to the direction in which the plasma flow is blown out from the gas outlet; a control means for detecting at least the temperature state of the sample in the reaction vessel and, based on the temperature state, adjusting the microwave power so that the state of the plasma flow and the surface temperature of the sample are maintained in predetermined states; The atmospheric pressure plasma processing apparatus is characterized in that the sample is exposed to the plasma flow and reacted with the plasma flow to perform surface processing of the sample.

5. 5. The atmospheric pressure plasma processing apparatus according to claim 4, wherein said control means is capable of adjusting said high frequency power so that the plasma flow reaches directly onto the surface of the sample.

6. 5. The atmospheric pressure plasma processing apparatus according to claim 4, wherein the control means is capable of adjusting the high frequency power so that the temperature of the surface of the sample that the plasma flow reaches is maintained at around 200[°C].

7. 5. The atmospheric pressure plasma processing apparatus according to claim 4, wherein the control means can set the microwave power value supplied to the high frequency resonant cavity to the maximum value that allows the plasma flow to reach the sample surface directly and maintain the sample surface temperature at around 200°C.

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