Method and device for determining a position of a leak on a component

Abstract

The invention relates to a method for determining a position (PL) of a leak (2) on a component (3), comprising: flowing a first gas (8a) into a volume (7) of the component (3) to be tested for a leak (2), which component is arranged in an interior (5) of a vacuum chamber (4), wherein a second gas (8b), which is different from the first gas, is located in the volume (7) to be tested, wherein the first gas (8a) is flowed into the volume (7) to be tested at an overpressure (∆p) in order to compress the second gas (8b) in the volume (7) to be tested; detecting a leakage rate of the first gas (8a) and / or a leakage rate (qL2) of the second gas (8b) which escapes at the leak (2) from the volume (7) to be tested into the interior (5) of the vacuum chamber (4); and determining the position (PL) of the leak (2) on the component (3) on the basis of a curve of the detected leakage rate of the first gas (8a) and / or the detected leakage rate (qL2) of the second gas (8b). The invention also relates to a device (1) for determining a position (PL) of a leak (2) on a component (3).

Description

[0001] Method and device for determining a position of a leak on a component

[0002] Reference to related application

[0003] This application claims priority from German patent application DE102023209077.5 filed on September 19, 2023, the entire disclosure of which is incorporated by reference into this application.

[0004] Background of the invention

[0005] The invention relates to a method for determining the position of a leak on a component. The invention also relates to a device for determining the position of a leak on a component.

[0006] To detect leaks in components, a so-called leak test is typically carried out. During the leak test, a volume of the component to be tested for leaks (e.g. a pipe, a cooling channel, etc.) is placed inside a vacuum chamber of a leak testing device. For the leak test, it is sufficient if only the volume of the component to be tested for leaks is placed inside the vacuum chamber, not the entire component. To carry out the leak test, the component to be tested is connected to a test gas connection in the device, and the vacuum chamber is evacuated. In a subsequent step, the test gas connection is pressurized with a test gas, which is usually helium. During the leak test, the component to be tested, or more precisely the volume of the component to be tested, is pressurized with the test gas at a pre-specified pressure.At the same time, a residual gas measurement or a pressure measurement is carried out in the interior of the vacuum chamber into which the volume of the component to be tested for leaks is placed.

[0007] In the event that a leak occurs in the volume of the component to be tested, the test gas escaping into the interior is detected, for example, by means of a residual gas analysis or by a pressure increase in the vacuum chamber. In this way, a statement can be made as to whether the volume of the component to be tested is tight or leaking. Based on the strength of the detected pressure increase, the integral (total) leak rate of the component to be tested can be quantified, i.e., the sum of the leak rates of all leaks in the volume of the component to be tested. However, with this integral leakage or tightness test, the position of the leak on the component cannot be localized.

[0008] EP0047324B1 describes a method for detecting a leak in a closed system using helium gas. In this method, a stream of sample gases is generated by withdrawing sample gases from the system. The stream of sample gases contains helium if a leak exists. By determining the helium content of the withdrawn sample gases, it can be determined whether a leak exists in the closed system.

[0009] DE10354234A1 describes a method for determining leaks or permeations in which a pressureless test specimen is exposed to an atmosphere with a controlled composition. A test medium, e.g., CO2, is introduced into the atmosphere via a signal source, and a measurement signal is generated at a connected measuring device. After the signal source is switched off and the test specimen is pressurized with the test medium and the test pressure, another measurement signal is generated. The leak rate is determined by comparing the two measurement signals.

[0010] DE102020207524B3 discloses a method for testing the tightness of at least one channel through which a fluid can flow, which is integrated into a component. The method comprises: introducing the component into a vacuum chamber, flowing a test gas through the channel, and testing the tightness of the channel by detecting a concentration of the test gas in the vacuum chamber. The method also comprises reducing a concentration of the test gas in the vacuum chamber before the test gas flows through the channel by purging the channel with a purge gas and / or evacuating the channel of the component introduced into the vacuum chamber.

[0011] The methods described above do not determine the position of the leak on the component.

[0012] DE102021210537A1 describes a method and a device for detecting the position of a leak on a component that is inserted into the interior of a vacuum chamber. The position of the leak is detected using a detector signal acquired by a detector connected to the interior at one detector position, as well as by detecting at least one further detector signal by at least one further detector connected to the interior at another detector position. To detect the position of the leak, a propagation time difference between the detector signal and the at least one further detector signal is determined.

[0013] Object of the invention The object of the invention is to provide a method and a device which enable the position of a leak on a component to be detected in a simple manner.

[0014] Subject of the invention

[0015] This object is achieved according to a first aspect by a method for detecting a position of a leak on a component, comprising: flowing a first gas into a volume of the component to be tested for leaks, which volume is arranged in an interior of a vacuum chamber, wherein a second gas, different from the first, is located in the volume to be tested, and wherein the first gas is flowed into the volume to be tested at an overpressure in order to compress the second gas in the volume to be tested, detecting a leak rate of the first gas and / or a leak rate of the second gas which escapes from the volume to be tested into the interior of the vacuum chamber at the leak, and determining the position of the leak on the component based on a curve of the detected leak rate of the first gas and / or the second gas.

[0016] In the method described here, the volume of the component to be tested is typically completely filled with the second gas before the first gas flows in, i.e. the second gas occupies the entire volume to be tested. If the first gas flows into the volume to be tested at overpressure, the overpressure of the first gas compresses the second gas and the second gas is displaced by the first gas, i.e. the partial volume occupied by the second gas within the volume to be tested decreases, while the partial volume occupied by the first gas increases. When the first gas flows into the volume to be tested at overpressure, a gas front is created which forms an interface between the partial volume occupied by the first gas and the partial volume occupied by the second gas. The position of the gas front within the volume to be tested depends on the overpressure of the first gas.depends on the pressure difference between the first gas and the second gas. The method described here typically assumes that the volume of the component to be tested is open only at one inflow position of the first gas and at the position of the leak when the first gas flows in.

[0017] A sufficiently fast process ensures that mixing effects between the two gases are uncritical for relevant applications. The method described here can also be used to detect the position of leaks that, due to permeation or diffusion processes, do not act quasi-instantly but are delayed (e.g., leaks with O-rings; larger volumes where the diffusion process between the two gases requires time, etc.).

[0018] For calibration purposes, the procedure can be performed multiple times to detect leaks at different, previously known positions. However, the position of the leak can also be determined without calibration using the procedure described here. The position of the leak can be determined, for example, through calculations taking the component's geometry into account. Further optimization can be achieved, for example, by gathering experience from repeated execution of the procedure, in which the position determined by the procedure is compared with the position of the leak determined by inspection of the component.

[0019] In one variant, the position of the leak is determined based on an increase in the detected leak rate of the first gas and / or a decrease in the detected leak rate of the second gas, which occurs when the first gas displaces the second gas at the position of the leak. In the variant of the method described here, typically only the leak rate of one of the two gases is detected. The value of the detected leak rate therefore depends strongly on whether the first gas or the second gas is located at the position of the leak. In the event that the leak rate of the second gas is detected, a generally steep drop in the leak rate occurs when the second gas is displaced by the first gas at the position of the leak, i.e. when the gas front formed between the first gas and the second gas reaches the position of the leak.In case the leak rate of the first gas is detected, a steep increase in the leak rate usually occurs as the first gas displaces the second gas at the position of the leak.

[0020] If the leak rates of the first gas and the second gas are detected, a simultaneous steep increase in the leak rate of the first gas and a steep decrease in the leak rate of the second gas usually occur when the first gas displaces the second gas at the position of the leak. In the event that the steep increase in the leak rate of the first gas and the steep decrease in the leak rate of the second gas occur at different times, a first value for the position of the leak can be determined based on the steep increase in the leak rate of the first gas, and a second value for the position of the leak can be determined based on the steep decrease in the leak rate of the second gas. In this case, the position of the leak can be determined, for example, by calculating the arithmetic mean of these two values.

[0021] In a further variant, the overpressure of the first gas flowing into the volume to be tested is preferably increased gradually. By increasing the overpressure, the gas front in the volume to be tested is shifted, whereby the partial volume filled with the first gas increases and the partial volume filled with the second gas decreases. When the first gas reaches the position of the leak, as described above, an increase in the detected leak rate of the first gas or a decrease in the detected leak rate of the second gas occurs, which can be assigned to a value of the overpressure of the first gas. In the event that the overpressure at which the decrease or increase in the leak rate occurs is comparatively small, the position of the leak is close to the inflow position of the first gas.If the overpressure at which the decrease or increase in the leak rate occurs has a larger value, the position of the leak is further away from the inflow position of the first gas.

[0022] In this variant, the overpressure of the first gas is generally not increased continuously, but gradually in small steps until a static pressure is established. The overpressure can be increased in steps of equal pressure increments of, for example, 0.1 bar(g). If a sharp drop or increase in the detected leak rate occurs between two pressure increments, the first gas has reached the leak location.

[0023] The method described here is typically used to determine the location of leaks that do not themselves cause a significant pressure drop relative to the pressure stage. The pressure of the first gas flowing into the volume to be tested can be regulated or adjusted to a desired value, for example, using a pressure regulator.

[0024] In a further variant, the volume to be tested has a first opening at an inflow position of the first gas and a second opening which is closed when the first gas flows in, wherein the first opening and the second opening are preferably located at opposite ends of the volume to be tested. As described above, when the first gas flows in, the volume to be tested is only open at the inflow position where the first opening is located and at the position of the leak. A second opening in the volume to be tested, which during operation of the component can be used together with the first opening, for example, to allow a fluid to flow through the volume to be tested, is closed during the inflow, for example by means of a plug or the like, so that the second gas is compressed in the volume to be tested when the first gas flows in.In this variant, the component can be, for example, a pipeline or a system of pipelines or a channel or a system of channels that are incorporated into the component and can be flowed through by a fluid.

[0025] In a further development of this variant, the second opening is opened after the first gas has flowed in, allowing the second gas to escape from the volume to be tested, reducing the overpressure. The second opening is located in the portion of the volume to be tested that is filled with the second gas. In this variant, the first gas can flow in at a constant overpressure, meaning the overpressure of the first gas does not necessarily have to be increased gradually, as is the case with the variant described above.

[0026] As described above, when the first gas flows in, the gas front is displaced from the inflow position at the first opening into the volume to be tested. When the overpressure is released by the second gas flowing out of the volume to be tested through the second opening, the gas front continues to move through the volume to be tested toward the second opening. The gas front is thus moved from the first opening toward the second opening both during the buildup and release of the overpressure. The second opening is preferably closed and opened using a switchable or controllable valve.

[0027] In a further development of this variant, the inflow of the first gas and the outflow of the second gas are preferably repeated several times. The position of the leak can also be detected in this case based on an increase in the leak rate of the first gas and / or a decrease in the leak rate of the second gas. In this case, the position of the leak is assigned to one of the repeatedly repeated steps of inflow or outflow. If the first gas flows in with a comparatively small overpressure, the steps with which the gas front is displaced within the volume to be tested are small, and the assignment allows the position of the leak to be determined with high spatial resolution.

[0028] In another variant, the first gas or the second gas is helium. In leak testing, helium is often used as the test gas, and the helium leak rate is detected. Accordingly, the method described here can use a conventional detector that is also used in an integral leak test to detect helium. The volume to be tested can, for example, be filled with helium as the second gas in order to carry out an integral leak test. If this has shown that the volume to be tested has a leak, a first gas, e.g. nitrogen, can be flowed into the volume to be tested, which is filled with helium as the second gas. Accordingly, the nitrogen leak rate can also be determined here, for example using a residual gas analyzer. Alternatively, the volume to be tested can be filled with air or with a purge gas, e.g.with nitrogen as the second gas and helium is the first gas to flow into the volume to be tested.

[0029] In a further variant, the method comprises: renewed inflow of the first gas starting from a further inflow position into the volume to be tested, preferably with reversal of a flow direction of the first gas, renewed detection of the leak rate of the first gas and / or the leak rate of the second gas escaping from the volume to be tested into the interior of the vacuum chamber at the leak, and renewed determination of the position of the leak on the component based on the detected leak rate of the first gas and / or the detected leak rate of the second gas. The renewed inflow of the first gas can take place in particular at the second opening described above. During the renewed inflow, the further inflow position is preferably selected at an end of the volume of the component to be tested opposite the inflow position.For example, if the component is a pipeline or a system of pipelines, or a duct or a system of ducts, the flow direction of the test gas can be reversed upon re-entry. This can improve the accuracy of determining the location of the leak.

[0030] For the renewed inflow, a gas supply, which is installed at the inflow position to supply the test gas, can be disconnected from the component to be tested and installed at the additional inflow position. In this case, the pressure regulator described above is also usually positioned at the additional inflow position to allow the first gas to flow into the volume to be tested again at a defined pressure. However, it is also possible to realize the inflow of the first gas at both inflow positions using a suitable gas supply, without requiring any modification of the device for determining the leak location.

[0031] A further aspect of the invention relates to a device for detecting a position of a leak on a component, comprising: a vacuum chamber with an interior space into which a volume of the component to be tested is introduced, a gas supply for the flow of a first gas into the volume of the component to be tested, wherein the first gas has an overpressure compared to a second gas, different from the first, which is located in the volume to be tested, a detector which is connected to the interior space of the vacuum chamber in order to detect a leak rate of the first gas and / or a leak rate of the second gas which escapes from the volume of the component to be tested at the leak, and an evaluation device for determining the position of the leak on the component based on a curve of the detected leak rate of the first gas and / or the detected leak rate of the second gas.

[0032] As described above, the evaluation device is designed or programmed to determine the position of the leak based on the detected leak rate of the first gas and / or the detected leak rate of the second gas, typically based on an increase in the detected leak rate of the first gas and / or a decrease in the detected leak rate of the second gas as the second gas is displaced by the first gas upon reaching the position of the leak. The evaluation device can be embodied in the form of suitable hardware and / or software.

[0033] The vacuum chamber can be part of a device that is specifically designed for the purpose of carrying out the leak test or determining the position of the leak. However, it is also possible for the vacuum chamber to be part of an optical system that fulfills other functions in addition to carrying out the leak test. For example, the device can be a lithography system, in particular an EUV lithography system. In this case, the component can be an optical element of the EUV lithography system, for example an optical element that reflects EUV radiation, in particular an EUV mirror, which is tested in situ for a leak. The optical element can, for example, have one or more channels or a system of channels as the volume to be tested, through which a fluid can flow, e.g. to control the temperature of the optical element.It is understood that other components can also be tested for the presence of a leak using the method or device described here, for example (pipe) lines or (pipe) line systems.

[0034] The detector is designed to detect a concentration or the increase in a concentration of the first gas and / or the decrease in a concentration of the second gas in the interior of the vacuum chamber and thus the leak rate of the first gas and / or the leak rate of the second gas. The use of a pressure gauge that determines (only) the total pressure in the interior is generally not possible for the determination of the leak location described here, since the determination of the specific leak rate of at least one of the two gases is typically required.

[0035] In one embodiment, the detector is a residual gas analyzer. The residual gas analyzer is typically a mass spectrometer that is installed on the vacuum chamber and communicates with the interior. The mass spectrometer can also be located in the interior of the vacuum chamber. A residual gas analyzer can distinguish the first gas and / or the second gas contained in the vacuum chamber from other gases present in the vacuum chamber based on their mass-to-charge ratio and detect their concentration or their partial pressure.

[0036] In a further embodiment, the gas supply has a pressure regulator for regulating the overpressure of the first gas as it flows into the volume to be tested. As described above, it is advantageous to regulate the pressure of the first gas as it flows to a predetermined value, which can be changed step by step, for example.

[0037] In a further embodiment, the gas supply has a first valve for the first gas to flow into the volume to be tested at a first opening and preferably a second valve for the first gas to flow into the volume to be tested at a second opening and / or for the first and / or second gas to flow out of the volume to be tested at the second opening. As described above in connection with the method, the first gas can flow into the volume to be tested at the second opening in order to again determine the position of the leak. However, the second valve can also be used to flow out the second gas in order to reduce the excess pressure in the volume to be tested. The two valves can in particular be located at two openings at opposite ends of the volume of the component to be tested.

[0038] In a further development of this embodiment, the gas supply has a bypass channel that connects the first opening to the second opening. By using the bypass channel, the pressurization with the first gas can occur from the inflow position at the first opening and from the further inflow position at the second opening, without any modification of the gas supply being necessary for this purpose. A further valve can be installed in the bypass channel to prevent the second gas from flowing back to the first opening via the bypass channel when flowing out at the second opening, and vice versa. However, the installation of a further valve in the bypass channel is not absolutely necessary.

[0039] In a further development, the gas supply has a further bypass channel that connects the first opening and the second opening to a gas outlet. Residual gas can be removed from the volume to be tested and the supply lines via the gas outlet from the first opening or the second opening, respectively, via the further bypass channel in order to define a precise zero point for locating the position of the leak. A further valve can be provided in the further bypass channel between the first opening and the gas outlet and between the second opening and the gas outlet to prevent the first gas from reaching the gas outlet when the volume to be tested is pressurized.

[0040] Further features and advantages of the invention will become apparent from the following description of exemplary embodiments of the invention, with reference to the figures of the drawing, which illustrate details essential to the invention, and from the claims. The individual features can be implemented individually or in combination in a variant of the invention.

[0041] drawing

[0042] Examples of embodiments are shown in the schematic drawing and are explained in the following description.

[0043] Fig. 1 is a schematic representation of a device for determining an integral leak rate on a component whose volume to be tested is filled with helium,

[0044] Fig. 2a-c are schematic representations of a device analogous to Fig. 1 , in which nitrogen is injected at overpressure into the volume to be tested in order to determine the position of a leak,

[0045] Fig. 3 is a schematic representation of the leak rate of helium escaping at the leak on the component to be tested,

[0046] Fig. 4a-c schematic representations analogous to Fig. 2a-c, in which the volume to be tested is filled with nitrogen and in which helium is injected into the volume to be tested at overpressure,

[0047] Fig. 5 is a schematic representation of a leak rate of helium escaping from the component to be tested at the leakage point,

[0048] Fig. 6a, b schematic representations analogous to Fig. 2a-c, in which nitrogen is flowed into the volume to be tested at an inflow position, Fig. 6c, d schematic representations analogous to Fig. 6a, b, in which

[0049] Nitrogen is injected into the volume to be tested at another inlet position with the flow direction reversed,

[0050] Fig. 7a-d schematic representations analogous to Fig. 2a-c, in which an overpressure is built up and released again in the volume to be tested, as well as

[0051] Fig. 8 is a schematic representation of a gas supply of the device of Fig. 7a-d, which serves to achieve a high spatial resolution.

[0052] In the following description of the drawings, identical reference symbols are used for identical or functionally identical components.

[0053] Fig. 1 shows a highly schematic view of the structure of a device 1 for detecting a leak 2, i.e. a (small) opening at which an unwanted gas escape from a component 3, indicated by an arrow in Fig. 1, occurs. In the example shown, the component 3 is a pipeline. However, the component 3 can also be a more complex component, for example a pipeline system, an optical element or an optical assembly, e.g. a projection system, an illumination system, etc. of a lithography system, e.g. an EUV lithography system, which has a channel or a channel system. The channel or the channel system can be designed so that a fluid can flow through it in order to control the temperature of the component.

[0054] The device 1 comprises a vacuum chamber 4, shown rectangular in Fig. 1, with an interior 5 into which the component 3 for the leak test is inserted. For the leak test, the interior 5 of the vacuum chamber 4 is evacuated using a pumping device (vacuum pump) not shown. The evacuation typically reduces the pressure in the interior 5 to less than 1 mbar, so that a molecular flow prevails in the interior 5, as is common in the high or ultra-high vacuum range.

[0055] The device 1 also has a gas supply 6, via which a gas 8 can be supplied to the component 3, more precisely to a volume 7 inside the component 3 to be tested for a leak 2, which is represented in Fig. 1 by a plurality of dots. In the example shown, the gas 8 is helium. To check whether a leak 2 occurs in the volume 7 of the component 3 to be tested, i.e. whether an undesired gas escapes into the interior space 5 of the vacuum chamber 4, the device 1 has a detector 9 which is connected to the interior space 5 of the vacuum chamber 4.

[0056] In the example shown in Fig. 1, the detector 9 is a residual gas analyzer designed to detect a concentration or partial pressure of the gas 8 in the interior 5 of the vacuum chamber 4. It is understood that another type of detector 9 suitable for detecting the partial pressure or concentration of the gas 8 in the interior 5 can also be used in the device 1.

[0057] For the leakage test, in the example described in Fig. 1, the volume 7 of component 3 to be tested is pressurized with gas 8. The gas 8 is supplied to the volume of component 3 to be tested via gas supply 6 using a pressure regulator 10 that is integrated into gas supply 6. Pressure regulator 10 serves to regulate a pressure p in volume 7 of component 3 to be tested in the form of a pipeline. As can be seen in Fig. 1, component 3 is closed at its end facing away from gas supply 6 by a blind flange 11. For the leakage test, in the example shown in Fig. 1, a constant pressure p is generated in volume 7 of component 3 to be tested by means of pressure regulator 10. At the leakage 2, the gas 8 escapes into the interior 5 of the vacuum chamber 4 and the concentration of the escaping gas 8 is detected by the detector 9.Based on the signal level detected by detector 9, the leak rate qi. or the size of the leak 2 can be quantified with the aid of an evaluation device 12—with suitable calibration. While the (integral) leak rate qi. can be quantified in this way, it is not possible to localize a position PL of the leak 2 on the component 3 along its longitudinal direction.

[0058] Fig. 2a-c show a device 1 designed to locate the leak 2, i.e., to detect the position PL of the leak 2 in the longitudinal direction of the component 3. The device 1 of Fig. 2a-c differs from the device 1 shown in Fig. 1, among other things, in that in addition to the gas 8, which is referred to below as the second gas 8b, a first gas 8a is or can be flowed into the volume 7 of the component 3 to be tested. In the example shown, the first gas 8a is a purge gas, more precisely nitrogen.

[0059] Fig. 2a shows an initial state for determining the position PL of the leak 2, in which the volume 7 to be tested is filled with helium as the second gas 8b, as shown in Fig. 1. To determine the position PL of the leak 2, the first gas 8a, i.e. nitrogen, flows into the volume 7 to be tested at an overpressure Ap, whereby the second gas 8b is compressed in the volume 7 to be tested. The overpressure Ap is defined as the pressure difference between the pressure pi of the first gas 8a and the original pressure p2 of the second gas 8b. As can be seen in Fig. 2b, due to the compression, a partial volume of the volume 7 to be tested filled by the second gas 8b decreases and a first partial volume filled with the first gas 8a increases. The two partial volumes are separated from each other along a gas front 13, the position P of which in the volume 7 to be tested depends on the overpressure Ap of the first gas 8a.The greater the overpressure Ap, the further the position P of the gas front 13 is from an inflow position E1 of the first gas 8a at a first end 14a of the volume 7 to be tested and the closer the position P of the gas front 13 is to the second end 14b of the volume 7 to be tested. The three positions P of the gas front 13 shown in Fig. 2a-c correspond to an overpressure Ap of 0 bar(g), of 0.3 bar(g) and of 1.1 bar(g), respectively.

[0060] In the method described in connection with Fig. 2a-c for determining the position PL of the leak 2, the overpressure Ap of the first gas 8a is gradually increased in small steps of 0.1 bar(g), whereby the position P of the gas front 13 moves in the volume 7 to be tested from the first end 14a toward the second end 14b. When the first gas 8a or the gas front 13 reaches the position PL of the leak 2 and displaces the second gas 8b at the position PL of the leak 2, a significant drop 15 in the leak rate qi_2 of the second gas 8b occurs, as can be seen in Fig. 3. The drop 15 in the leak rate qi_2, which is detected by the detector 9, can be assigned by the evaluation device 12 to the overpressure Ap of approximately 1.0 bar(g) at which the gas front 13 reaches the position PL of the leak 2.Based on the overpressure Ap at which the drop 15 in the leak rate qi_2 of the second gas 8b occurs, the evaluation device 12 can deduce the position PL of the leak 2 in the longitudinal direction of the component 3 - for example based on a previous calibration.

[0061] Fig. 4a-c show the device 1 of Fig. 1, in which nitrogen is present as the second gas 8b in the volume 7 to be tested, which is used, for example, as a purge gas in the leak test described in connection with Fig. 1. In this example, helium is introduced as the first gas 8a into the volume 7 to be tested at an overpressure Ap, which is increased step by step, as described in connection with Fig. 2a-c. In the example shown in Fig. 4a-c, the leak rate qn of the first gas 8a, i.e. of helium, is detected with the aid of the detector 9. As shown in Fig. 5, in this case an increase 16 in the leak rate qu occurs when the first gas 8a reaches the position PL of the leak 3. Based on the increase 16 in the leak rate qu of the first gas 8a, the position PL of the leak 2 can be determined, as described above.

[0062] If the leak rates qi, q2 of the first gas 8a and the second gas 8b are detected, a simultaneous steep increase in the leak rate qi of the first gas 8a and a steep decrease in the leak rate q2 of the second gas 8b generally occur when the first gas 8a displaces the second gas 8b at the position PL of the leak 2. In the event that the steep increase in the leak rate qu of the first gas 8a and the steep decrease in the leak rate qi_2 of the second gas 8b are offset in time, a first value for the position of the leak 2 can be determined based on the steep increase in the leak rate qu of the first gas 8a, and a second value for the position of the leak 2 can be determined based on the steep decrease in the leak rate qi_2 of the second gas 8b. In this case, the position PL of the leak 2 can be determined, for example, by calculating the arithmetic mean of these two values.

[0063] Fig. 6a-d show a further development of the method described in connection with Fig. 2a-c, which serves to improve the localization of the leak 2. In the further development, the position PL of the leak 2 is first detected in the manner described in connection with Fig. 2a-c by the first gas 8a in the form of nitrogen flowing in through a first opening 01 at the inflow position E1 at the first end 14a of the volume 7 to be tested. A second opening 02 at the second end 14b of the volume 7 to be tested is closed by means of a blind flange 11, as described above.

[0064] In the further development, the volume 7 of the component 3 to be tested is first purged with a purge gas, for example nitrogen, in order to remove residues of the two gases 8a, b from the volume 7 to be tested. After purging, the gas supply 6 is mounted at a second end 14b of the component 3 opposite the first. Nitrogen is again flowed into the volume 7 to be tested as the first gas 8a through a second opening 02 at a further inflow position E2 at the second end 14b of the component 3, as shown in Fig. 6c, d. A flow direction R2 of the first gas 8a is opposite a flow direction R1 of the first gas 8a, which flowed into the volume 7 to be tested from the inflow position E1 at the first end 14a during the determination of the position PL of the leak 2 described in connection with Fig. 2a-c or Fig. 6a, b.

[0065] As can also be seen in Fig. 6a-d, the two openings 01, 02 of the component 2 are located at the lateral edge of the vacuum chamber 4. The supplied first gas 8a therefore does not reach the interior 5 of the vacuum chamber 4, neither when flowing in at the inflow position E1 nor when flowing in at the further inflow position E2.

[0066] The renewed determination of a position PL' of the leakage 2 takes place as described above in connection with Fig. 2a-c or Fig. 6a, b, ie by renewed detection of the leakage rate qi_2 of the second gas 8b during the renewed inflow of the first gas 8a. The position PL' of the leakage 2 on the component 3 is determined analogously to Fig. 2a-c or Fig. 6a, b based on the detected leakage rate qi_2 or based on the drop 15 in the leakage rate qi_2 of the second gas 8b.

[0067] As indicated in Fig. 6a, b and Fig. 6c, d by two different reference symbols PL, PL', when the method is carried out for the first time as described in connection with Fig. 6a, b, a position PL of leak 2 can be determined that differs from the position PL' during the subsequent determination. The deviation may be due to measurement inaccuracies. To increase the accuracy of locating leak 2, an average value can be calculated from the two positions PL, PL'.

[0068] Fig. 7a-d show a further possibility for determining the position PL of the leak 2 on the component 3, in which, in a first step, as shown in Fig. 2a-c, nitrogen as the first gas 8a with an overpressure Ap, which in the example shown is 0.6 bar(g), is flowed into the volume 7 to be tested via the first opening 01 at the inflow position E1. As a result, the second gas 8b is compressed and the gas front 13 is displaced away from the inflow position E1 in the volume 7 to be tested, as can be seen in Fig. 7b. After the inflow with the overpressure Ap of 0.6 bar(g) and the reaching of a static pressure, the overpressure Ap is not increased, unlike in Fig. 2a-c. Rather, the overpressure Ap is reduced by opening the second opening 02 at the second end 14b of the component 3 by means of a (second) valve V2 until the overpressure is 0 bar(g).

[0069] As the second gas 8b flows out through the second opening 02, the partial volume of the volume 7 to be tested that is filled with the second gas 8b decreases, and the gas front 13 moves towards the second end 14b, as shown in Fig. 7c. In the step shown in Fig. 7d, the first gas 8a again flows into the volume 7 to be tested at the inflow position E1 at an overpressure of 0.6 bar(g), causing the gas front 13 to move further towards the second end 14b of the component 3. In a subsequent step (not shown), the overpressure Ap can be reduced again and is at 0 bar(g).

[0070] During the alternating build-up and release of the overpressure Ap described above, the leak rate qi_2 of the second gas 8b is detected. The drop 15 in the leak rate qi_2 when the first gas 8a reaches the position PL of the leak 2 can be determined by the evaluation device 12 and assigned to a respective step of the build-up or release of the overpressure Ap. Based on the assignment to the respective step, the position PL of the leak 2 in the volume 7 to be tested can be deduced. It is understood that the displacement of the position P of the gas front 13 in a respective step of the release or build-up of the overpressure Ap in Fig. 7a-d was chosen to be comparatively large for the sake of clarity, but to achieve high spatial resolution when determining the position PL of the leak 2, it is generally chosen to be significantly smaller than shown in Fig. 7a-d.

[0071] Fig. 8 shows a detailed illustration of a device 1 with a gas supply 6, with which the methods described in connection with Figs. 6a-d and 7a-d can be carried out particularly efficiently. The gas supply 6 has a first valve V1 at the first opening O1 of the volume 7 to be tested of the component 3, to which the first gas 8a is supplied from the pressure regulator 10 or from a gas inlet not shown. The gas supply 6 also has the second valve V2 described in connection with Figs. 7a-d at the second opening O2 of the volume 7 to be tested.

[0072] The gas supply 6 further comprises a bypass channel 17a, which connects the first opening 01 outside the volume 7 to be tested with the second opening 02. Through the bypass channel 17a, the first gas 8a can be supplied to both the first valve V1 at the first opening 01 and the second valve V2 at the second opening 02, without requiring any modifications to the gas supply 6 for this purpose, as is the case with the method described in connection with Figs. 6a-d.

[0073] In order to prevent the first gas 8a from reaching the second opening O2 via the bypass channel 17a when the overpressure Ap is reduced in the method described in connection with Fig. 7a-d, the first valve V1 can be closed after the first gas 8a has flowed into the volume 7 to be tested. The overpressure Ap in the bypass channel 17a is then reduced and only then is the second valve V2 opened to reduce the overpressure Ap in the volume 7 to be tested. A similar procedure can be followed when the second gas 8b flows into the volume 7 to be tested via the second opening O2, ie the second valve V2 is first closed and the overpressure Ap in the bypass channel 17a is reduced before the first valve V1 is opened to reduce the overpressure Ap in the volume 7 to be tested.It is also possible to arrange a further valve in the bypass channel 17a in order to prevent gas from passing between the first opening 01 and the second opening 02 via the bypass channel 17a.

[0074] As can also be seen in Fig. 8, the gas supply 6 has a further bypass channel 17b which is connected to a gas outlet 18. The further bypass channel 17b serves to remove residual gas from the volume 7 to be tested via the gas outlet 18 starting from the first opening O1 or from the second opening O2 and to fill the lines up to the openings O1, O2 or up to the valves V1, V2 with the first or second gas 8a, 8b, which flows into the volume 7 to be tested. In order to define a precise zero point for locating the position PL of the leak 2, it is essential that the respective gas 8a, 8b is located directly in front of the respective valve V1, V2 before opening, which can be ensured by a bypass purge. In the further bypass channel 17b, a third valve V3 is arranged between the first opening 01 and the gas outlet 18.Likewise, a fourth valve V4 is arranged between the second opening 02 and the gas outlet 18 in the further bypass channel 17b. The third and fourth valves V3, V4 are closed when the volume 7 to be tested is pressurized with the first gas 8a.

Claims

Patent claims 1 . Method for determining a position (PL) of a leak (2) on a component (3), comprising: Inflow of a first gas (8a) into a volume (7) of the component (3) to be tested for leakage (2), which volume is arranged in an interior (5) of a vacuum chamber (4), wherein a second gas (8b) different from the first is located in the volume (7) to be tested, wherein the first gas (8a) is flowed into the volume (7) to be tested at an overpressure (Ap) in order to to compress volume (7), Detecting a leak rate (qu) of the first gas (8a) and / or a leak rate (qi_2) of the second gas (8b) which escapes at the leak (2) from the volume (7) to be tested into the interior (5) of the vacuum chamber (4), and Determining the position (PL) of the leak (2) on the component (3) based on a profile of the detected leak rate (qu) of the first gas (8a) and / or the detected leak rate (qi_2) of the second gas (8b).

2. Method according to claim 1, wherein the position (PL) of the leak (2) is determined based on an increase in the detected leak rate (qu) of the first gas (8a) and / or based on a decrease in the detected leak rate (qi_2) of the second gas (8b) which occurs when the first gas (8a) displaces the second gas (8b) at the position (PL) of the leak (2).

3. Method according to claim 1 or 2, wherein the overpressure (Ap) of the first gas (8) flowing into the volume (7) to be tested is preferably increased stepwise.

4. Method according to one of the preceding claims, in which the volume to be tested (7) has a first opening (01) at an inflow position (E1) of the first gas (8a) and a second opening (02) which is closed when the first gas (8a) flows in, wherein the first opening (01) and the second opening (02) are preferably located at opposite ends (14a,b) of the volume to be tested (7).

5. Method according to claim 4, wherein after the inflow of the first gas (8a) the second opening (02) is released in order to reduce the excess pressure (Ap) by the outflow of the second gas (8b) from the volume (7) to be tested.

6. Method according to claim 5, wherein the closing and opening of the second opening (02) is carried out by means of a valve (V2).

7. Method according to claim 5 or 6, wherein the inflow of the first gas (8a) and the outflow of the second gas (8b) are repeated several times.

8. Method according to one of the preceding claims, wherein the first gas (8a) or the second gas (8b) is helium.

9. Method according to one of the preceding claims, further comprising: renewed inflow of the first gas (8a) starting from a further inflow position (E2) into the volume (7) to be tested, preferably by reversing a flow direction (R1) of the first gas (8a), renewed detection of the leak rate (qu) of the first gas (8a) and / or the Leakage rate (qi_2) of the second gas (8b) escaping from the volume (7) to be tested into the interior (5) of the vacuum chamber (4) at the leakage (2), and Re-determining the position (PL') of the leak (2) on the component (3) based on the detected leak rate (qu) of the first gas (8a) and / or the detected leak rate (qi_2) of the second gas (8b).

10. A device for determining a position (PL) of a leak (2) on a component (3), comprising: a vacuum chamber (4) with an interior (5) into which a volume (7) of the component (3) to be tested is introduced, a gas supply (6) for the flow of a first gas (8a) into the volume (7) of the component (3) to be tested, wherein the first gas (8a) has an overpressure (Ap) relative to a second gas (8b) different from the first and located in the volume (7) to be tested, a detector (9) connected to the interior (5) of the vacuum chamber (4) to detect a leak rate (qu) of the first gas (8a) and / or a leak rate (qi_2) of the second gas (8b) escaping from the volume (7) of the component (3) to be tested at the leak (2),and an evaluation device (12) for determining the position (PL) of the leak (2) on the component (3) based on a profile of the detected leak rate (qu) of the first gas (8a) and / or the detected leak rate (qL2) of the second gas (8b)., 11.Device according to claim 10, wherein the detector (9) is designed as a residual gas analyzer.

12. Device according to claim 10 or 11, wherein the gas supply (6) has a pressure regulator (10) for regulating the overpressure (Ap) of the first gas (8a) as it flows into the volume (7) to be tested.

13. Device according to one of claims 10 to 12, wherein the gas supply (6) has a first valve (V1) for the inflow of the first gas (8a) into the volume to be tested (7) at a first opening (01) and preferably a second valve (V2) for the inflow of the first gas (8a) into the volume to be tested (7) at a second opening (02) and / or for the outflow of the first and / or the second gas (8a, 8b) from the volume to be tested (7) at the second opening (02).

14. Device according to claim 13, wherein the gas supply (6) has a bypass channel (17a) which connects the first opening (01) to the second opening (02).

15. Device according to claim 13 or 14, wherein the gas supply (6) has a further bypass channel (17b) which connects the first opening (01) and the second opening (02) to a gas outlet (18).

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