Atmospheric pressure plasma processing equipment

Abstract

To provide an atmospheric pressure plasma processing method and an atmospheric pressure plasma processing apparatus which perform sample processing in a short time and reduce the number of processing steps. [Solution] The apparatus includes a plasma generator 3 that supplies a rotating flow of pressurized inert gas from a gas inlet 38 to the inner surface of a reaction cylinder 31, and supplies microwaves controlled to a predetermined power amount to a high-frequency resonant cavity 34 to generate plasma, a reaction vessel 5 having an approximately cross shape, a sample moving mechanism 7 that enables a sample SF to be moved relative to the plasma flow within the reaction vessel 5, and a control means 9 that controls the plasma generation state according to the state of the sample, and performs plasma processing on the sample surface under atmospheric pressure.

Description

[Technical field]

[0001] The present invention relates to a method for treating the surface of a sample by irradiating the sample with a plasma flow under atmospheric pressure. Large The present invention relates to a pressure plasma processing apparatus. [Background technology]

[0002] As is well known, polytetrafluoroethylene (PTFE) is a material that can be said to be the ultimate material in many respects. In particular, it is attracting attention as a circuit board material in recent years because it is not only heat-resistant but also has the lowest high-frequency loss factor. However, since PTFE does not have sufficient hardness and strength, it needs to be reinforced with epoxy resin, etc. to be used as a substrate. However, the difficulty of adhering PTFE 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 able to achieve a certain degree of increase in adhesive strength, it still has the drawback of being weak in terms of mechanical strength. To overcome this drawback, a boron-hydrogen treatment method was proposed. 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), but 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 provide a relatively large increase in the mechanical strength of the sample, and can also increase the adhesive strength of the sample.

[0005] Furthermore, Non-Patent Document 3 clarified more detailed plasma conditions, processing time, sample heating temperature, and chemical causes of improvement in adhesive strength by heating for the thermally assisted plasma method, which were not clarified in Non-Patent Document 2. With this device, a sample in a directly heated state is subjected to plasma processing, and a layer called WBL that is left on the sample surface due to the temperature rise 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 the adhesive strength, but on the other hand, the rough surface causes the following drawbacks. That is, when PTFE treated by the conventional thermally assisted plasma method is used for an electronic circuit board, the signal delay time worsens as the roughness of the circuit board surface increases. Since the roughness of the PTFE surface is related to the plasma treatment time, long-term plasma treatment is not preferable.

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

[0009] As described above, conventional plasma processing techniques had the disadvantage of being unable to satisfy the conflicting demands 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 that it cannot satisfy one of the industrial requirements for sample processing in the shortest possible time. Furthermore, according to the above-mentioned conventional technology, it is necessary to preheat the sample to several hundred degrees, which is inconvenient in that it does not satisfy one of the industrial requirements for performance, that is, to reduce the number of steps as much as possible.

[0010] The present invention overcomes the above-mentioned disadvantages of the prior art, and can perform sample processing in a short time while eliminating unnecessary processing steps and reducing the number of processing steps. Large To provide a high pressure plasma processing apparatus. [Means for solving the problem]

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

[0012] The atmospheric pressure plasma processing apparatus according to claim 1 includes a reactor tube and a pressurized inert gas. high frequency 1. An atmospheric pressure plasma processing apparatus for generating plasma in a reaction tube and performing surface processing of a sample with a plasma flow blown out of the reaction tube, comprising: a plasma generating device that provides a gas inlet and a gas outlet in the reaction tube, provides a high-frequency resonant cavity so as to surround the outer periphery of the reaction tube, supplies a pressurized inert gas from the gas inlet into the reaction tube while rotating it, and supplies a high-frequency wave to the high-frequency resonant cavity to generate plasma in the reaction tube and blow out a plasma flow from the gas outlet of the reaction tube; A gas inlet and a gas outlet are provided in a linear cylindrical shape, and a cylindrical sample insertion port is provided at a right angle to these ports to form a substantially cross shape. The gas inlet A reaction vessel having the above components connected thereto; a sample moving mechanism that can be arranged in a direction of a 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 a blowing direction of a plasma flow blown out from the gas ejection part; In the reaction vessel Sample surface temperature At the very least, the plasma flow state and Surface temperature of the sample and to maintain the specified state. The amount of high frequency power and a control means for adjusting the The sample is exposed to the plasma flow and reacts with the plasma flow to perform surface treatment of the sample.

[0013] In the atmospheric pressure plasma processing apparatus according to claim 2, in claim 1, Pressurized Inert Gas The gas used is argon gas or a mixture of argon gas and helium gas in a predetermined amount.

[0014] The atmospheric pressure plasma processing apparatus according to claim 3 is an atmospheric pressure plasma processing apparatus which supplies argon gas or a gas obtained by mixing a predetermined amount of argon gas and helium gas, and microwaves into a reaction cylinder to generate plasma in the reaction cylinder, and performs surface processing of a sample by the plasma flow blown out of the reaction cylinder, a plasma generating device that provides a gas inlet and a gas outlet in the reaction cylinder, provides a cooling cylinder so as to surround the outer periphery of the reaction cylinder, provides a high frequency resonant cavity so as to surround the outer periphery of the cooling cylinder, supplies pressurized argon gas from the gas inlet into the reaction cylinder as a rotating flow, cools the reaction cylinder by flowing a cooling medium through the cooling cylinder, supplies microwaves of a predetermined amount of power to the high frequency resonant cavity to bring the high frequency resonant cavity into a resonant state, generates plasma in the reaction cylinder, and blows out a plasma flow from the gas outlet of the reaction cylinder; a reaction vessel having a gas inlet and a gas outlet provided linearly and a cylindrical sample insertion port provided perpendicularly thereto, forming a substantially cross-shaped reaction vessel, the gas inlet being connected to a gas outlet portion of the reaction tube; a sample moving mechanism that moves the sample in the reaction vessel relative to a direction in which the plasma flow is blown out from the gas outlet; In the reaction vessel Sample surface temperature At the very least, the plasma flow state and Surface temperature of the sample and to maintain the specified state. The amount of microwave power and a control means for adjusting the The sample is exposed to the plasma flow and reacts with the plasma flow to perform surface treatment of the sample.

[0015] In the atmospheric pressure plasma processing apparatus according to claim 4, in claim 3, The control means adjusts the amount of microwave power supplied to the high frequency resonant cavity to an amount of power that ensures that the plasma flow reaches directly onto the surface of the sample. It is characterized by the above.

[0016] In the atmospheric pressure plasma processing apparatus according to claim 5, in claim 3, The control means adjusts the amount of microwave power supplied to the high-frequency resonant cavity to an amount that can maintain the surface temperature of the sample that the plasma flow is reaching at around 200°C. It is characterized by the above.

[0017] The atmospheric pressure plasma processing apparatus according to claim 6 further comprises the steps of: The control means can set the amount of microwave power supplied to the high frequency resonant cavity to a maximum value at which the plasma flow can reach the surface of the sample directly and the surface temperature of the sample can be maintained at approximately 200°C. It is characterized by the above. Effect of the Invention

[0018] According to the present invention, the plasma flow can be reliably delivered to the sample, the surface temperature of the sample can be maintained at a predetermined temperature, and the sample and the plasma flow can be moved relatively to each other, so that the following effects are obtained. (1) It is possible to satisfy the conflicting requirements of shortening the treatment time to suppress the roughness of the sample surface and lengthening the treatment 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 reduce the number of processes as much as possible. [Brief description 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; [Diagram 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; [Diagram 3] FIG. 11 is a characteristic diagram showing peel strength versus processing time of a sample processed by the atmospheric plasma processing apparatus according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] The following describes an embodiment of the present invention. Large The atmospheric 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 a main part 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 equipped with a plasma generating device 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 device 3 is exposed to a PTFE sample SF for reaction, a sample moving mechanism 7 in which the sample SF is detachably arranged and capable of moving 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 device 3 and the surface temperature of the sample SF to control the plasma generation state of the plasma generating device 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 integrally provided on the same axis as the reaction cylinder 31 so as to surround the outer periphery of the reaction cylinder 31 also made of quartz, an electromagnetic shield 33 provided on the same axis as the reaction cylinder 31 so as to surround the outer periphery of the cooling cylinder 32, and a high-frequency resonant cavity 34 provided on the same axis as 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 wave guide 36c, and a three-stub tuner 36d.

[0023] The reaction tube 31 is made of quartz in a long cylindrical shape as shown in Figures 1 and 2. The reaction tube 31 is provided with a gas inlet 37 at the center of the upper side as shown in the figure, and gas inlets 38, 38 at the outer peripheral surface of the cylinder at the upper side as shown in the figure. In addition, a gas outlet 39 is provided at the lower part of the reaction tube 31 as shown 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, 38 are configured to be supplied with Ar gas via a mass flow controller (MFC) 41. The gas inlets 38, 38 are arranged to face diagonally downward in the figure and to be shifted in the tangential direction of the outer periphery of the reaction tube 31, so that the Ar gas introduced from the gas inlets 38, 38 rotates downward in the figure along the inner periphery of the reaction tube 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 tube 31 becomes a plasma flow Pf and is discharged from the gas outlet 39.

[0025] The cooling cylinder 32 is made of quartz as shown in Figures 1 and 2, and is arranged so as to surround the outer periphery of the reaction cylinder 31 coaxially with the central axis 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 to the upper side of 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 is configured in a substantially cross shape by a vertical cylinder and a horizontal cylinder as shown in Figures 1 and 2. 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. The horizontal cylinder is provided with insertion ports 53, 53 for the sample SF on the left side in Figures 1 and 2 and on the right side in Figures 1 and 2. The gas inlet 51 has a smaller diameter going upward in Figures 1 and 2, and is finally made 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 joined 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 in which the sample SF reacts with the plasma flow Pf.

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

[0028] When the hollow drum tube 70 is disposed 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 rotating 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 relatively 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 generating device 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 spectrometer that can take in each of the detection lights from the optical fibers 92, 94 and create a control command CS based on 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 microwaves μW based on the control command CS. The microwaves μW whose power value has been controlled in this manner are supplied to the high frequency resonant cavity 34 via a circulator 36a, a power meter 36b, a wave guide 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 configured as above, the plasma processing of the PTFE sample SF is carried out as follows.

[0032] CO2 gas is mixed with N2 gas through a mass flow controller (MFC) 40c, and Ar gas is mixed with N2 gas through an MFC 40n, and Ar gas is mixed with N2 gas through an MFC 40a in a predetermined amount and supplied from a gas inlet 37 into the reaction tube 31. The supply of these gases may be performed as necessary, but is not essential.

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

[0034] In addition, as mentioned above, while rotating Reaction tube 31 The Ar gas moving downward along the inner circumferential surface is, for example, an inert gas (CO2 gas, N2 gas, Ar gas) introduced from the gas inlet 37. Reaction tube 31 When the inert gases are supplied to the inside of the nozzle, the rotational force is transmitted to the inert gases (CO2 gas, N2 gas, and Ar gas) as they descend.

[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 about 3,000 to 4,000°C is generated in 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 from the gas inlet 51 into the reaction vessel 5. The high-temperature plasma generated in the reaction cylinder 31 is gradually cooled by the cooling medium R flowing in the cooling cylinder 32 provided on the outer periphery of the reaction cylinder 31 while flowing down along the gas flow, and finally flows out as a plasma flow Pf from the gas outlet 39. This realizes 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 position 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 realizes a step of exposing (exposing) the sample SF to the plasma flow Pf while moving the sample SF in a direction perpendicular to the blowing direction of the plasma flow Pf. In addition, in order to avoid an excessive increase in surface temperature due to direct contact of the plasma flow Pf with the surface of the sample SF, and to avoid temporal and spatial non-uniformity in exposure of the plasma flow Pf to the surface of the sample SF, in this embodiment, 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, so for example, the sample SF may be moved at a predetermined speed in the direction of the insertion ports 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 to a control unit 95 including a spectroscope via an optical fiber 92, and detection light from an optical sensor unit 93 that detects the surface temperature of the sample SF is supplied to a control unit 95 including a spectroscope via an optical fiber 94. The control unit 95 can form 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) generated.

[0040] By this control command CS, the amount of power of the microwaves μW generated by the magnetron generator 35 is controlled, 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 tube 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 specified 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 a maximum value such that the above (a) and (b) are satisfied simultaneously.

[0041] The atmospheric 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 conflicting requirements of shortening the treatment time to suppress the roughness of the sample surface and extending the treatment 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 satisfies one of the industrial requirements for reducing the number of processes as much as possible. EXAMPLES

[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 the description in Fig. 2, the dimensions are not limited to these, and it goes without saying that dimensions other than these may be used as long as the same operational effects can be 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 cylinder 31. A reaction vessel 5 was placed at a position at a length La = 9.5 [cm] below the lower end side 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 the 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 the insertion ports 53, 53 and the vertical cylinder including the gas inlet 51 and the gas outlet 52 form the reaction vessel 5 in a substantially cross shape. In the sample moving mechanism 7, the total length Lc of the aluminum (Al) hollow drum tube 70 was set to Lc=160 [mm], and the outer diameter d was set to d=20 [mmφ].

[0044] The hollow drum tube 70 has the sample SF wound around its center. 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 tube 70 is inserted from the insertion opening 53 on the left side (one side) of FIG. 2 of the horizontal cylinder of the reaction vessel 5. Then, one end of the hollow drum tube 70 is brought out from 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 tube 70 is finally set in the center position of the reaction vessel 5 as shown in FIG. 1 and FIG. 2. When set up in this manner, as shown in FIG. 1, one end of the hollow drum tube 70 is rotatably fixed to a fixed portion 71, and the other end of the hollow drum tube 70 is fixed to a rotating shaft 72 of a motor M. The motor M rotates the hollow drum tube 70, thereby moving the sample SF wrapped around the center of the hollow drum tube 70.

[0045] After the sample SF is placed in the above-mentioned state, plasma is generated in the reaction tube 31 of the plasma generator 3, and the high-temperature plasma flow PF is irradiated 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 directly onto the surface of the sample SF, and the surface temperature of the sample SF reached by the plasma flow Pf becomes about 200°C. These controls are performed based on a 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 directly on the surface of the sample SF and the surface temperature of the sample SF reached by the plasma flow Pf is approximately 200°C, that is, so as to simultaneously satisfy two requirements.

[0046] P The plasma flow PF freely flows out into the atmosphere from the gap between the insertion openings 53, 53 of the reaction vessel 5 and the hollow drum tube 70, or from the gas exhaust opening 52. Therefore, the processing portion (processing space) of the sample SF becomes a semi-free space blowing type.

[0047] In addition, it is necessary to avoid an excessive rise in the surface temperature of the sample SF due to the direct contact of the plasma flow Pf with the surface of the sample SF, and to avoid the time during which the plasma flow Pf reaches the surface of the sample SF and the spatial non-uniformity of the plasma flow Pf, it is necessary to move the surface of the sample SF at a relatively high speed. For this reason, in this embodiment, the hollow drum tube 70 is rotated at a rotation speed of 6 [rpm]. This allows the desired performance to be obtained. The reason for exposing the sample SF to the plasma while rotating it on the hollow drum tube 70 in this way is also 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 forcibly circulate water, air or other cooling medium, but it is also possible to allow 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 embodiment 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 gave the maximum peel strength.

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

[0051] In the above-mentioned test, the test results are shown in FIG. 3, with the maximum measured value Max being indicated by a solid line and the average measured value Mean being indicated by a dotted line. In this strength peel test, as shown in Figure 3, when the treatment time was short, the peel strength was small, but as the treatment time was longer, the peel strength increased accordingly, and the maximum peel strength was 2 kN / m after 42 seconds of treatment. -1 ], exceeding the highest value (1.2 [kN / m -1 ]) was obtained. Furthermore, when the treatment time was increased beyond the time at which the maximum peel strength was obtained (42 seconds treatment), the peel strength gradually decreased. From this result, it can be seen that optimizing the treatment time is an important factor in obtaining the maximum peel strength.

[0052] From the above, in an embodiment of the atmospheric pressure plasma processing apparatus according to the present invention, it can be seen that the following conditions are suitable for surface treatment 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) reaches directly onto the surface of the sample SF. (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 should be set to the maximum value that satisfies both "Condition 1" and "Condition 2" at the same time. (Condition 4) The surface of the sample SF must be moved at a relatively high speed 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 temporal and spatial non-uniformity in exposure of the plasma flow Pf to the surface of the sample SF.

[0053] Generally, when the peel strength is low, adhesive components and oxygen absorbed 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 a 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, since it was found that there is a high possibility that this will have an adverse effect on the adhesive strength, it is preferable to only have an Ar gas flow from the gas inlet 38. In addition, measurements using a surface roughness meter before and after treatment under the highest peel strength conditions showed no significant change in roughness. , surface melting due to temperature rise, and etch pits formed due to contact with plasma flow. No change was observed.

[0055] According to an embodiment of the atmospheric pressure plasma processing apparatus of the present invention, a PTFE sample treated with this apparatus was subjected to a pressure of 2 [kN / m -1 ] peel strength exceeding that of conventional adhesives could be achieved, and the processing speed could be achieved in seconds, resulting in the following advantages: (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, one of the industrial requirements, that is, to minimize the number of steps, can be satisfied. [Explanation of symbols]

[0056] 1. Atmospheric pressure plasma processing equipment 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 exhaust port 53, 53 Insertion port 70 Hollow Drum Pipe 91, 93 Sensor section 92, 94 Optical fiber 95 Control Device

Claims

1. 1. An atmospheric pressure plasma processing apparatus for supplying a pressurized inert gas and a high frequency wave into a reaction tube to generate plasma in the reaction tube and for performing surface processing of a sample by using a plasma flow blown out of the reaction tube, a plasma generating device that provides a gas inlet and a gas outlet in the reaction tube, provides a high-frequency resonant cavity so as to surround the outer periphery of the reaction tube, supplies a pressurized inert gas from the gas inlet into the reaction tube while rotating it, and supplies a high-frequency wave to the high-frequency resonant cavity to generate plasma in the reaction tube and blow out a plasma flow from the gas outlet of the reaction tube; a reaction vessel having a linear cylindrical gas inlet and gas outlet, a cylindrical sample insertion port provided at right angles to the gas inlet and gas outlet, and a generally cross-shaped reaction vessel, the gas inlet being connected to a gas outlet of the reaction tube; a sample moving mechanism that can be arranged in a direction of a 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 a blowing direction of a plasma flow blown out from the gas ejection part; a control means for detecting at least a surface temperature of the sample in the reaction vessel and, based on the detected temperature, adjusting the amount of high frequency power so that the state of the plasma flow and the surface temperature of the sample are maintained in a predetermined state; 2. An atmospheric pressure plasma processing apparatus comprising: a sample being exposed to the plasma flow and reacting with the plasma flow to perform surface processing of the sample; 2. The atmospheric pressure plasma processing apparatus according to claim 1, wherein the pressurized inert gas is argon gas or a gas obtained by mixing a predetermined amount of argon gas and helium gas.

3. An atmospheric pressure plasma processing apparatus which supplies argon gas or a gas obtained by mixing a predetermined amount of argon gas and helium gas and microwaves into a reaction tube to generate plasma in the reaction tube, and performs surface processing of a sample by using a plasma flow blown out of the reaction tube, a plasma generating device that provides a gas inlet and a gas outlet in the reaction cylinder, provides a cooling cylinder so as to surround the outer periphery of the reaction cylinder, provides a high frequency resonant cavity so as to surround the outer periphery of the cooling cylinder, supplies pressurized argon gas from the gas inlet into the reaction cylinder as a rotating flow, cools the reaction cylinder by flowing a cooling medium through the cooling cylinder, supplies microwaves of a predetermined amount of power to the high frequency resonant cavity to bring the high frequency resonant cavity into a resonant state, generates plasma in the reaction cylinder, and blows out a plasma flow from the gas outlet of the reaction cylinder; a reaction vessel having a gas inlet and a gas outlet provided linearly and a cylindrical sample insertion port provided perpendicularly thereto, forming a substantially cross-shaped reaction vessel, the gas inlet being connected to a gas outlet portion of the reaction tube; a sample moving mechanism that moves the sample in the reaction vessel relative to a direction in which the plasma flow is blown out from the gas outlet; a control means for detecting at least a surface temperature of a sample in the reaction vessel and, based on the detected surface temperature, adjusting the amount of power of the microwave so that the state of the plasma flow and the surface temperature of the sample are maintained in predetermined states; 2. An atmospheric pressure plasma processing apparatus comprising: a sample being exposed to the plasma flow and reacting with the plasma flow to perform surface processing of the sample;

4. An atmospheric pressure plasma processing apparatus as described in claim 3, characterized in that the control means adjusts the amount of microwave power supplied to the high frequency resonant cavity to an amount of power that ensures that the plasma flow reaches directly onto the surface of the sample.

5. An atmospheric pressure plasma processing apparatus as described in claim 3, characterized in that the control means adjusts the amount of microwave power supplied to the high-frequency resonant cavity to an amount of power capable of maintaining the surface temperature of the sample reached by the plasma flow at a surface temperature of around 200°C.

6. An atmospheric pressure plasma processing apparatus as described in claim 3, characterized in that the control means can set the amount of microwave power supplied to the high-frequency resonant cavity to a maximum value at which the plasma flow reaches directly onto the surface of the sample and the surface temperature of the sample can be maintained at a surface temperature of around 200°C.

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