X-ray tube with improved spectrum

Abstract

Method for assembling an X-ray window (14) with a target (17), the method comprising: Applying an adhesive layer (16) to the X-ray window (14); Deposition of a target (17) on the adhesive layer (16) with a gap (21) on the X-ray window (14) that is free of the target (17) and surrounds the target (17), wherein the target (17) is configured to generate X-rays in response to incident electrons from an electron emitter (11e) and the target (17) contains a noble metal; Applying a conductive layer (18) to the X-ray window (14) in the slit (21), wherein the conductive layer (18) borders the target (17), wherein an area on the target (17) is free of the conductive layer (18), and wherein the conductive layer (18) is electrically conductive; and Mounting the X-ray window (14) on a flange (19) of an anode (12) for an X-ray tube (10, 80, 190, 260, 310) by means of a sealing layer (13), wherein the flange (19) encloses an opening (22), the X-ray window (14) spans the opening (22) and the target (17) is spaced apart from the flange (19) by the gap (21).

Description

Scope of the invention

[0001] This application relates to X-ray sources. background

[0002] X-rays have many applications, including imaging, X-ray fluorescence analysis, X-ray diffraction analysis, and electrostatic discharge capability.

[0003] By applying a high voltage between the cathode and anode of an X-ray tube, and sometimes a heated filament, electrons can be emitted from the cathode to the anode. The anode may contain a target. The target can generate X-rays in response to the electrons striking it from the cathode.

[0004] US 2014 / 0 177 800 A1 relates to a target structure equipped with an insulating substrate and a target provided on a surface of the insulating substrate.

[0005] US 2016 / 0133430A1 relates to an anode comprising: a target layer configured to generate X-rays; a support substrate extending outward beyond an edge of the target layer, the support substrate comprising a support surface on which the target layer is supported; a tubular anode element connected to a side face of the support substrate by means of a connecting element, the connecting element comprising an extended section extending from the side face to the support surface; and a conductive element having a higher melting point than the connecting element. Brief description of the drawings (the drawings may not be to scale) Fig. Figure 10 shows a side view in cross-section of an X-ray tube 10 with an X-ray window 14, sealed with a flange 19. A target 17 can be attached to the X-ray window 14 by means of an adhesive layer 16. The adhesive layer 16 can have several different thicknesses (Ts ≠ Tt, Tg ≠ Tt). A gap 21 can be present between the flange 19 and the target 17. A conductive layer 18 can be located on the adhesive layer 16 in the gap 21. Fig. is a top view of X-ray tube 10 from Fig. , recorded along section 2-2 in Fig. . Fig. is a side view in cross-section of a step 30 in a method for assembling an X-ray window 14 with a target 17, including the application of a first adhesive layer 16a to the X-ray window 14. Fig. is a side view in cross-section of a step 40 in a method for assembling an X-ray window 14 with a target 17 that can follow step 30, including the application of a second adhesive layer 16b in an opening 42 of a mask 41. Fig. is a side view in cross-section of a step 50 in a method for assembling an X-ray window 14 with a target 17 that can follow step 40, including the application of a target 17 to the second adhesive layer 16b in the opening 42 of the mask 41. Fig. is a side view in cross-section of a step 60 in a method for assembling an X-ray window 14 with a target 17, which may follow step 50, including removing the mask 41s from step 50, applying a second mask 41 to the target 17 and subsequently applying a conductive layer 18 to the adhesive layer 16 between the target 17 and on an outer circumference of the X-ray window 14. Fig. is a side view in cross-section of a step 70 in a method for assembling an X-ray window 14 with a target 17, which may follow step 50 or step 60, including attaching the X-ray window to a flange 19 of an anode 12 for an X-ray tube by means of a sealing layer 13. Fig. Figure 1 shows a side view in cross-section of an X-ray tube 80 with an X-ray window 14, sealed with a flange 19. A target 17 can be attached to an X-ray window 14 by means of an adhesive layer 16. The adhesive layer 16 can have several different thicknesses (Ts ≠ Tt, Tg ≠ Tt). A conductive layer 18 can be located on the adhesive layer 16 in a gap 21 between the flange 19 and the target 17. Fig. is a top view of the X-ray tube 80 from Fig. , recorded along section 9-9 in Fig. . Fig. Figure 1 is a side view in cross-section of a step 100 in a method for assembling an X-ray window 14 with a target 17, including the application of an outer adhesive layer 16o to the X-ray window 14 and the subsequent application of a conductive layer 18 to the outer adhesive layer 16o. The outer adhesive layer 16o and the conductive layer 18 can be applied in a ring 92. The ring 92 can enclose an opening 91. Fig. is a side view in cross-section of a step 110 in a method for assembling an X-ray window 14 with a target 17, which may follow or precede step 100, including the application of a medium adhesive layer 16c to the X-ray window 14 in an opening 91 enclosed by a ring 92. Fig. is a side view in cross-section of a step 120 in a method for assembling an X-ray window 14 with a target 17 that may follow step 110, including the application of a target 17 to the middle adhesive layer 16c. Fig. is a side view in cross-section of a step 130 in a method for assembling an X-ray window 14 with a target 17, which may follow step 120, including attaching the X-ray window to a flange 19 of an anode 12 for an X-ray tube by means of a sealing layer 13. Fig. is a side view in cross-section of a step 140 in a method for assembling an X-ray window 14 with a target 17, including the application of an adhesive layer 16 to the X-ray window 14. Fig. is a side view in cross-section of a step 150 in a method for assembling an X-ray window 14 with a target 17 that can follow step 140, including the application of a mask 41 to the adhesive layer 16 and the subsequent etching of the adhesive layer 16 at an opening 42 of the mask. Fig. is a side view in cross-section of a step 160 in a method for assembling an X-ray window 14 with a target 17 that may follow step 150, including the application of a target 17 to the adhesive layer 16 at the opening 42 of the mask 41. Fig. is a side view in cross-section of a step 170 in a method for assembling an X-ray window 14 with a target 17, which may follow step 160, including the removal of the mask 41, the application of a second mask 41s to the target 17 and the subsequent application of a conductive layer 18 to the adhesive layer 16 surrounding the target 17. Fig. is a side view in cross-section of a step 180 in a method for assembling an X-ray window 14 with a target 17, which may follow step 160 or step 170, including the removal of the mask 41 or the second mask 41s and the subsequent application of the X-ray window 14 to a flange 19 of an anode 12 for an X-ray tube by means of a sealing layer 13. Fig. Figure 1 shows a side view in cross-section of an X-ray tube 190 with an X-ray window 14, sealed with a flange 19. A target 17 can be attached to the X-ray window 14 by means of an adhesive layer 16. A gap 21 may be present between the flange 19 and the target 17. A conductive layer 18 may be located on the adhesive layer 16 and / or on the X-ray window 14 within the gap 21. The adhesive layer 16 can span the gap 21 between the target 17 and a sealing layer 13 on the circumference of the X-ray window 14. Fig. is a top view of the X-ray tube 190 from Fig. , recorded along section 20-20 in Fig. . Fig. is a side view in cross-section of a step 210 in a method for assembling an X-ray window 14 with a target 17, including the application of an adhesive layer 16 to a surface of the X-ray window 14. Fig. Figure 220 is a side view in cross-section of a step 220 in a method for assembling an X-ray window 14 with a target 17, which may follow step 210, including the application of a mask 41 to the adhesive layer 16. The mask 41 may have an opening 42 that exposes the adhesive layer 16. Fig. is a side view in cross-section of a step 230 in a method for assembling an X-ray window 14 with a target 17 that may follow step 220, including the application of a target 17 to the adhesive layer 16 in the opening 42 of the mask 41. Fig. is a side view in cross-section of a step 240 in a method for assembling an X-ray window 14 with a target 17, which may follow step 230, including the removal of the mask 41, the application of a second mask 41s to the target 17 and the subsequent application of a conductive layer 18 to the adhesive layer 16 on an outer circumference of the target 17. Fig. is a side view in cross-section of a step 250 in a method for assembling an X-ray window 14 with a target 17, which may follow step 230 or step 240, including attaching the X-ray window to a flange 19 of an anode 12 for an X-ray tube by means of a sealing layer 13. Fig. Figure 1 shows a side view in cross-section of an X-ray tube 260 with an X-ray window 14, sealed with a flange 19. A target 17 can be attached to an X-ray window 14 by means of an adhesive layer 16. A gap 21 can be present between the flange 19 and the target 17, as well as between the flange 19 and the adhesive layer 16. A conductive layer 18 can be located on the X-ray window 14 in the gap 21. Fig. is a top view of the X-ray tube 260 from Fig. , recorded along section 27-27 in Fig. . Fig. Figure 280 is a side view in cross-section of a step 280 in a method for assembling an X-ray window 14 with a target 17, which includes applying an adhesive layer 16 to an X-ray window 14 and then applying a target 17 to the adhesive layer 16. A gap 21 can enclose the adhesive layer 16 and the target 17. Fig. is a side view in cross-section of a step 290 in a method for assembling an X-ray window 14 with a target 17 that can follow step 280, including the application of a conductive layer 18 to the X-ray window 14 in the gap 21. Fig. Figure 1 is a top view of a mask 301 that can be used in process step 60 or step 290. The mask 301 contains openings 302 in which the conductive layer 18 can be applied. Fig. Figure 1 is a side view in cross-section of an X-ray tube 310 with X-ray window 14, sealed with flange 19. A layer stack in the middle of the X-ray window 14 can comprise the X-ray window 14, a first adhesive layer 16a, a conductive layer 18, a second adhesive layer 16b and finally a target 17. Fig. is a top view of the X-ray tube 310 from Fig. , recorded along section 32-32 in Fig. . Fig. is a side view in cross-section of a step 330 in a method for assembling an X-ray window 14 with a target 17, including the application of a first adhesive layer 16a to the X-ray window 14. Fig. is a side view in cross-section of a step 340 in a method for assembling an X-ray window 14 with a target 17 that may follow step 330, including the application of a conductive layer 18 to the first adhesive layer 16a. Fig. is a side view in cross-section of a step 350 in a method for assembling an X-ray window 14 with a target 17, which may follow step 340, including the application of a mask 41 to the conductive layer 18 having an opening 42 of the mask 41 and the subsequent application of a second adhesive layer 16b to the conductive layer 18 in the opening 42 of the mask 41. Fig. is a side view in cross-section of a step 360 in a method for assembling an X-ray window 14 with a target 17 that can follow step 350, including the application of a target 17 to the second adhesive layer 16b in the opening 42 of the mask 41. Reference numbers in the drawings 10, 80, 190, 260, 310 X-ray tube 11 Cathode 11e Electron emitter 12 Anode 13 Sealing layer 14 X-ray windows 15 cylinders 16 adhesive layer 16a First period of detention 16b Second detention period 16c Medium adhesive layer 16o Outer adhesive layer 17 Target 18 Management Layer 19 flange 21 column 22 Opening 41 mask 41s Second Mask 42 Opening 301 Mask 302 Opening 16 thicknesses T16, Ts, Tt, Tg of the adhesive layer 17 Thickness T17 of the target Definitions. The following definitions, including their plurals, are valid for the entire patent application.

[0006] The term "mask opening" used here refers to an opening in an inner area of ​​the mask, which is not necessarily located exactly in the center of the mask. The term "center" is used to distinguish it from an edge.

[0007] The term “enclose” used here means that a ring is formed around the enclosed object, but is not limited to a circular shape.

[0008] The terms "on", "at", "at" and "over" used here mean "directly on" or "over", with another solid material in between. The terms "directly at", "adjacent", "adjacent to" and "lying beside", mean direct and immediate contact.

[0009] The term "X-ray tube" used here is not limited to X-ray or cylindrical devices. The term "tube" is used because it is the standard term for X-ray equipment. Detailed description

[0010] As shown in the figures, an X-ray tube can contain a cathode 11 (with an electron emitter 11e) and an anode 12, which are electrically isolated from each other (e.g., by a glass or ceramic cylinder 15). The anode 12 can contain a target 17. The target 17 faces the electron emitter 11e and can generate X-rays in response to the electrons incident from the electron emitter 11e.

[0011] X-rays can be used for material identification. An X-ray beam from an X-ray tube with the expected energy peaks can strike a sample. The X-rays fluoresced by the sample can be analyzed to determine its composition. If the X-ray beam from the X-ray tube contains unwanted or unexpected energy peaks, the material analysis may be inaccurate.

[0012] Therefore, it can be advisable to avoid generating X-rays from materials other than Target 17. X-rays generated by materials other than Target 17 can contaminate the X-ray beam. X-ray contamination from some materials is more severe than from others.

[0013] Strong adhesion of the target 17 to the X-ray window 14 is desirable. If the adhesion is weak, the X-ray tube may fail.

[0014] A robust hermetic seal for the X-ray window 14 is advisable. If this hermetic seal fails, the X-ray tube may fail.

[0015] The design and method of the X-ray window 14 and the target 17 described here can prevent contamination of the X-ray beam, ensure strong adhesion of the target 17 to the X-ray window 14 and enable a robust hermetic seal of the X-ray window 14.

[0016] The anode 12 can have a flange 19 that encloses an opening 22. The X-ray window 14 can be hermetically sealed to the flange 19. The X-ray window 14 can span the opening 22. A target 17 can be attached to the opening 22 in the center of the X-ray window 14 by means of an adhesive layer 16.

[0017] The X-ray window 14 can be hermetically sealed to the flange 19 by a sealing layer 13. If the material of the sealing layer 13 is similar to the material of the target 17 and / or the adhesive layer 16, the material of the sealing layer 13 can penetrate or diffuse into the opening 22. If a precious metal or titanium from the target 17 or the adhesive layer 16 comes into contact with the sealing layer 13, the materials of the sealing layer 13 can penetrate or diffuse into the opening 22. In both cases, X-rays can then be generated from the material of the sealing layer 13. These X-rays can contaminate the X-ray beam.

[0018] To avoid this problem and obtain a purer X-ray beam, the sealing layer 13 can be significantly different from the target 17 and / or the adhesive layer 16. This difference can minimize the interdiffusion or penetration of the material of the sealing layer 13 with the material of the target 17 and / or the adhesive layer 16.

[0019] For example, ≥ 80, ≥ 90, ≥ 95, ≥ 99 or 100 weight percent of the chemical elements of the sealing layer 13 may differ from the chemical elements of the target 17, the adhesive layer 16 or both.

[0020] The sealing layer 13 can form a hermetic seal by brazing. Thus, the sealing layer 13 can be a brazed connection or seal. The sealing layer 13 can contain silver, copper, or both. The sealing layer 13 cannot contain titanium. A large percentage (e.g., ≥ 95, ≥ 99, or 100 wt%) of the sealing layer 13 can consist of silver, copper, or both.

[0021] Another example: ≥ 95, ≥ 99 or 100 wt% of the sealing layer 13 may consist of silver, copper, titanium or combinations thereof, but the target 17 and the adhesive layer 16 may be at some distance from the sealing layer 13 and / or consist of a material that does not contain titanium.

[0022] A gap 21 may exist between flange 19 and target 17. The gap 21 may be annular. The sealing layer 21 may surround the target 17. The gap 21 may be free of the target 17. The target 17 may be at a distance from the sealing layer 13. In these examples, the sealing layer is therefore not adjacent to or in contact with the target 17.

[0023] The target 17 can consist of a precious metal such as gold, silver, platinum, palladium, rhodium, ruthenium, iridium, osmium, or combinations thereof. At least 80, 90, 95, or 99 percent by mass of the target can consist of a precious metal. The use of such a precious metal is made possible by the gap 21 between the target 17 and the sealing layer 13. Even if there is some material similarity between the sealing layer 13 and the target 17, interdiffusion of materials can be avoided. Examples of thickness T17 (see Fig. ) of target 17 are ≥ 0.5 µm and ≤ 10 µm.

[0024] The adhesive layer 16 may contain titanium, especially if the adhesive layer 16 has a certain distance to the sealing layer 13 (see Fig. ), or if the sealing layer 13 does not contain titanium. As in Fig. As shown, a gap 21 can exist between the flange 19 and the adhesive layer 16. The gap 21 can be free of the adhesive layer 16. The gap 21 can enclose the adhesive layer 16.

[0025] The sealing layer 13 can be titanium-free, and / or the adhesive layer 16 can be titanium-free. The adhesive layer 16 can contain chromium. The adhesive layer 16 can contain, for example, ≥ 85, ≥ 90, ≥ 95, or ≥ 99% chromium by mass. Chromium is preferred for strong adhesion of the target 17. Example thicknesses T16 (see Fig. ) of the adhesive layer 16 are ≥ 10 nm and ≤ 100 nm.

[0026] The adhesive layer 16 can span the gap 21 between the target 17 and the sealing layer 13, the flange 19 or both (see Fig. The adhesive layer 16 can be adjacent to the sealing layer 13, the flange 19, or both.

[0027] A conductive layer 18 may be located on the X-ray window 14 in slit 21. The conductive layer 18 is optional in all examples described here. The conductive layer 18 may extend from the target 17 to the flange 19.

[0028] The conductive layer 18 can extend over the flange 19 and be arranged between the sealing layer 13 and the X-ray window 14, as shown in the Fig. This is preferable for reasons of manufacturability, since an outer ring does not need to be covered to prevent the application of the conductive layer 18.

[0029] Alternatively, the conductive layer 18 can terminate at an inner edge of the flange 19 and the sealing layer 13, as shown in Fig. This is preferable if the material of the conductive layer 18 is not compatible with the hermetic seal.

[0030] The conductive layer 18 can be electrically conductive and establish an electrical connection between the target 17 and the flange 19. Therefore, it is advantageous to have a conductive layer 18 if the X-ray window 14 is electrically insulating.

[0031] The conductive layer 18 can contain tungsten, molybdenum, or both. X-rays generated in chromium can be more problematic than those generated in tungsten or molybdenum. Therefore, coating a chromium adhesion layer 16 with tungsten or molybdenum can improve the X-ray spectrum. The conductive layer 18 is preferred in X-ray tubes 10, 80, 190, and 310 because, in these examples, the adhesion layer 16 spans the gap 21. In these examples, the conductive layer 18 can cover the adhesion layer 16 and minimize X-ray contamination.

[0032] As in Fig. As shown, the conductive layer 18 can cover a small portion of the gap 21, for example, ≥ 5% and ≤ 50%. In this example, the X-ray window 14 can be electrically insulating, and the conductive layer 18 can establish an electrical connection between the target 17 and the anode 12. The adhesive layer 16 does not extend into the gap 21. Therefore, the gap does not need to be completely covered by the conductive layer 18. Thus, in this example, only one or more small channels of the conductive layer 18 are required for the electrical connection.

[0033] As shown for X-ray tubes 10, 80, 190, and 310, the conductive layer 18 can cover a large portion of the gap 21, such as ≥ 50%, ≥ 75%, or even the entire gap 21. In these examples, the conductive layer 18 is used to cover the adhesive layer 16. It is preferable to cover the entire adhesive layer 16 in the gap 21, but in the example of Fig. Masking is easier. Fig. A mask 301 with openings 302 is shown, in which the conductive layer 18 can be applied. This allows the conductive layer 18 to be shaped as shown in Fig. depicted.

[0034] X-ray window 14 may contain diamond. For example, X-ray window 14 may contain ≥ 85, ≥ 90, ≥ 95, or ≥ 99 percent diamond by mass. X-ray window 14 may be electrically insulating. X-ray window 14 may be electrically conductive. X-ray window 14 may contain beryllium, aluminum, or other electrically conductive materials.

[0035] Each example described here has advantages and disadvantages that must be weighed against each other. Below you will find specific examples along with their respective advantages and disadvantages.

[0036] In the following method, the steps can be performed in the described order. Components can have the properties described above. Sputtering can be used for the application steps. A method for assembling an X-ray window 14 with a target 17 can include some or all of the following steps: Applying an adhesive layer 16 to an X-ray window 14 (see Fig. ); Deposition of a target 17 on the adhesive layer 16 with a gap 21 at the X-ray window 14, which is free of the target 17 and surrounds the target 17, wherein the target 17 is configured to generate X-rays in response to incident electrons from an electron emitter 11e; (see Fig. ) Applying a conductive layer 18 to the X-ray window 14 in the slit 21, wherein the conductive layer 18 is adjacent to the target 17 and the conductive layer 18 is electrically conductive (see Fig. ); and

[0037] Mounting of the X-ray window 14 on a flange 19 of an anode 12 for an X-ray tube by means of a sealing layer 13, wherein the flange 19 encloses an opening 22, the X-ray window 14 spans the opening 22 and the target 17 has a certain distance to the flange 19 through the gap 21 (see Fig. ).

[0038] The gap 21 can be free of the adhesive layer 16, and the conductive layer 18 can be applied to ≥ 5% and ≤ 50% of the gap. See Fig. .

[0039] The adhesive layer 16 can extend into the gap 21, and the conductive layer 18 can cover ≥ 75% of the adhesive layer in the gap. See Fig. The adhesive layer 16 can span and cover the gap 21. See Fig. . X-ray tube 10 & 80

[0040] As in the Fig. As shown, the adhesive layer 16 can have several different thicknesses (Ts ≠ Tt, Tg ≠ Tt). These thickness differences can result from the properties shown in the Fig. The methods described result. The adhesive layer 16 can be inserted between the sealing layer 13 and the X-ray window 14, thereby improving the hermetic seal.

[0041] As in the Fig. As shown, a first adhesive layer 16a can be applied to the X-ray window 14. The vacuum chamber can be opened to apply a mask 41. The first adhesive layer 16a can oxidize. The X-ray window 14 can be reinserted into the vacuum chamber. A second adhesive layer 16b can be applied to the oxidized first adhesive layer 16a in an opening 42 of the mask 41. The target 17 can then be applied to the second adhesive layer 16b in the opening 42 of the mask 41 without opening the vacuum chamber.

[0042] By applying the first adhesive layer 16a over the X-ray window and subsequently applying the second adhesive layer 16b in the opening 42 of the mask 41, the adhesive layer 16 can have several different thicknesses (thicker middle).

[0043] X-ray tube 10 of the Fig. can be done according to the procedure of Fig. can be produced. Thus, a maximum thickness Ts of the adhesive layer 16 between the sealing layer 13 and the X-ray window 14 can be smaller than a minimum thickness Tt of the adhesive layer 16 between the target 17 and the X-ray window 14 (Ts < Tt). A maximum thickness Tg of the adhesive layer 16 in the gap 21 can be smaller than a minimum thickness Tt of the adhesive layer 16 between the target 17 and the X-ray window 14 (Tg < Tt).

[0044] Examples of relationships between these different thicknesses Ts, Tt and Tg include the following: 1.1*Ts ≤ Tt, 1.3*Ts ≤ Tt, 1.5*Ts ≤ Tt, 2*Ts ≤ Tt, or 10*Ts ≤ Tt; 1.1*Tg ≤ Tt, 1.3*Tg ≤ Tt, 1.5*Tg ≤ Tt, 2*Tg ≤ Tt, or 10*Tg ≤ Tt.

[0045] As in the Fig. As shown, an outer adhesive layer 16o can be applied immediately before the conductive layer 18 is applied, without breaking the vacuum in the chamber. A central adhesive layer 16c can be applied immediately before the target 17 is mounted, also without breaking the vacuum in the chamber. This prevents oxidation of the adhesive layer surfaces 16c and 16o before the top layer 17 or 18 is bonded, thus improving the adhesive strength.

[0046] Therefore, the outer adhesive layer 16o and the middle adhesive layer 16c can be applied in separate steps to improve adhesion. As a result, the adhesive layer 16 can have several different thicknesses Ts, Tt, and Tg because it is applied in different steps. These thickness differences are described above (thicker in the middle Tt) and below (thinner in the middle Tt). The X-ray tubes 10 and 80 of the Fig. can according to the procedure of Fig. to be manufactured.

[0047] As in the Fig. As shown, the adhesive layer 16 can be applied to the X-ray window 14. The vacuum chamber can be opened to apply a mask 41. The adhesive layer 16 can oxidize while the vacuum chamber is open. The X-ray window 14 can be reinserted into the vacuum chamber. The adhesive layer 16 can be etched in an opening 42 of the mask 41, thereby removing the oxidation and preparing the adhesive layer 16 for the application of the target 17. By etching the adhesive layer 16 within the opening 42 and subsequently applying the target 17 in this opening 42, the adhesive layer 16 can be thinner in the center. The X-ray tube 80 of the Fig. can be done according to the procedure of Fig. to be manufactured.

[0048] Therefore, the minimum thickness Ts of the adhesive layer 16 between the sealing layer 13 and the X-ray window 14 can be greater than the maximum thickness Tt of the adhesive layer 16 between the target 17 and the X-ray window 14 (Ts > Tt). A minimum thickness Tg of the adhesive layer 16 in the gap 21 can be greater than a maximum thickness Tt of the adhesive layer 16 between the target 17 and the X-ray window 14 (Tg > Tt).

[0049] Examples of relationships between these different thicknesses Ts, Tt, and Tg include the following: 1.1*Tt ≤ Ts, 1.3*Tt ≤ Ts, 1.5*Tt ≤ Ts, 2*Tt ≤ Ts, or 10*Tt ≤ Ts; 1.1*Tt ≤ Tg, 1.3*Tt ≤ Tg, 1.5*Tt ≤ Tg, 2*Tt ≤ Tg, or 10*Tt ≤ Tg.

[0050] A disadvantage of the X-ray tubes 10 and 80 is that the material of the sealing layer 13 can interdiffusion with the material of the adhesive layer 16. To minimize this interdiffusion, it is advantageous that (a) the material of the sealing layer 13 is different from the material of the adhesive layer 16, (b) the sealing layer 13 does not contain titanium, (c) the adhesive layer 16 does not contain titanium, (d) or combinations thereof.

[0051] A potential disadvantage of the X-ray tubes 10 and 80 is that the adhesive layer 16 in the gap 21 can impair the purity of the desired X-ray spectrum. To eliminate or reduce this problem, a conductive layer 18 can be applied to the adhesive layer 16 in the gap 21. The conductive layer 18 can absorb most of ( Fig. ) or the entire adhesive layer 16 ( Fig. ) block in the gap 21. The conductive layer 18 can be made of a material (e.g., tungsten W, molybdenum Mo, or both) that less interferes with the desired X-ray spectrum. The conductive layer 18 can be located between the adhesive layer 16 and the sealing layer 13, or it can terminate before or at an edge of the sealing layer 13.

[0052] If the X-ray window is electrically insulating, the adhesive layer 16 and / or the conductive layer 18 can establish an electrical connection between the target 17 and the anode 12.

[0053] A sequence of layers on an outer ring of the X-ray window 14 can consist of or include the X-ray window 14, the adhesive layer 16, the conductive layer 18, the sealing layer 13, and the flange 19. A sequence of layers in the center of the X-ray window 14 can consist of or include the X-ray window 14, the central adhesive layer 16, and the target 17.

[0054] In the following procedure for assembling an X-ray window 14 with a target 17, the steps can be performed in the described order. Components can have the properties described above. Sputtering can be used for the application steps. The procedure can include some or all of the following steps: Step 30 (see Fig. ) can include the application of a first adhesive layer 16a to an X-ray window 14. Step 40 (see Fig. Step 40 can include applying a mask 41 to the first adhesive layer 16a. The mask 41 can have an opening 42 that exposes the first adhesive layer 16a. The opening 42 can be located in the center of the mask 41. Step 40 can further include applying a second adhesive layer 16b to the first adhesive layer 16a in the opening 42 of the mask 41. Step 50 (see Fig. ) can include applying a target 17 to the second adhesive layer 16b in the opening 42 of the mask 41. Step 60 (see Fig. ) can include removing the mask 41, applying a second mask 41s to the target 17 and subsequently applying a conductive layer 18 to the adhesive layer 16 in a gap 21 on an outer circumference of the target 17. Step 70 (see Fig. This can follow step 50 or step 60. In step 70, mask 41 or the second mask 41s can be removed, then the X-ray window 14 is hermetically sealed to a flange 19 of the anode 12 by a sealing layer 13. The first adhesive layer 16a can be located between the sealing layer 13 and the X-ray window 14. The first adhesive layer 16a can connect to the sealing layer 13 at the X-ray window 14. The sealing layer 19 can enclose the opening 22. The X-ray window 14 can span the opening 22. The target 16 can be positioned at a certain distance from the flange 19 via a gap 21.

[0055] The adhesive layer 16 can be used to bond the sealing layer 13 to the X-ray window 14. Therefore, step 30 can involve applying the adhesive layer 16 over most or all of the surface of the X-ray window 14.

[0056] It may be advantageous to maintain a certain distance between the target 17 and the sealing layer 13 to prevent interdiffusion of these materials. The mask 41 from step 50 can limit the application of the target 17 to the center of the adhesive layer 16.

[0057] During the application of the mask 41, the adhesive layer 16 can oxidize; this can impair the adhesion of the target 17 to the adhesive layer 16. To solve this problem, the second layer 16b of the adhesive layer 16 can first be applied inside the mask 41, then the target 17 can be applied to the second layer 16b without breaking the vacuum and thus without oxidizing the surface of the second layer 16b.

[0058] In the following procedure for assembling an X-ray window 14 with a target 17, the steps can be performed in the following order. Components can have the properties described above. Sputtering can be used for the application steps. The procedure can include some or all of the following steps: In step 100 (see Fig. An outer adhesive layer 16o can be applied to the X-ray window 14, then a conductive layer 18 can be applied to the outer adhesive layer 16o. The outer adhesive layer 16o and the conductive layer 18 can form a ring 92 with an opening 91 that exposes the X-ray window 14. Step 110 (see Fig. ) can include the application of a medium adhesive layer 16c to the X-ray window 14 in the opening 91. Step 120 (see Fig. ) can include the application of a target 17 to the middle adhesive layer 16c. The target 17 can be applied in the opening 91. Step 130 (see Fig. ) can include the fastening of the X-ray window 14 to a flange 19 of an anode 12 for an X-ray tube 70 by means of a sealing layer 13.

[0059] The opening 91 can be formed by applying a mask to a central area of ​​the X-ray window 14 and subsequently applying the outer adhesive layer 16o and the conductive layer 18 around the circumference of the mask. Alternatively, the opening 91 can be formed by applying the outer adhesive layer 16o and then the conductive layer 18 over an area of ​​the X-ray window 14 and then etching a central area of ​​the outer adhesive layer 16o and the conductive layer 18 to form a ring 92, with the opening 91 exposing the X-ray window 14.

[0060] This method can lead to different thicknesses of the outer adhesive layer 16o compared to the middle adhesive layer 16c (Ts ≠ Tt, Tg ≠ Tt) because they are applied in different steps (100 & 110).

[0061] In the following procedure for assembling an X-ray window 14 with a target 17, the steps can be performed in the following order. Components can have the properties described above. Sputtering can be used for the application steps. The procedure can include some or all of the following steps: Step 110 (see Fig. ) may include the application of a medium adhesive layer 16c to the X-ray window 14. Step 120 (see Fig. ) can include the application of a target 17 to the middle adhesive layer 16c. The middle adhesive layer 16c and the target 17 can be arranged in a central region of the X-ray window 14, with a ring 92 on the X-ray window surrounding the middle adhesive layer and the target. In step 100 (see Fig. An outer adhesive layer 16o can be applied to the X-ray window 14, and then a conductive layer 18 can be applied to the outer adhesive layer 16o. The outer adhesive layer 16o and the conductive layer 18 can be applied within the ring 92. The ring 92 can enclose an opening 91. The middle adhesive layer 16c and the target 17 can be located within the opening 91. Step 130 (see Fig. ) can include the fastening of the X-ray window 14 to a flange 19 of an anode 12 for an X-ray tube 70 by means of a sealing layer 13.

[0062] The opening 91 can be formed by applying an annular mask with a central opening. Alternatively, the middle adhesive layer 16c and the target 17 can be applied to a surface of the X-ray window 14, and then an outer ring of the middle adhesive layer 16c and the target 17 can be removed by etching.

[0063] The outer adhesive layer 16o and the conductive layer 18 can form a ring around the opening 91 by using a second mask (not shown) on the target 17, or by applying it over an area of ​​the X-ray window 14 and then etching a central area.

[0064] This method can lead to different thicknesses of the outer adhesive layer 16o compared to the middle adhesive layer 16c (Ts ≠ Tt, Tg ≠ Tt) because they are applied in different steps (100 & 110).

[0065] In the following procedure for assembling an X-ray window 14 with a target 17, the steps can be performed in the following order. Components can have the properties described above. Sputtering can be used for the application steps. The procedure can include some or all of the following steps: Step 140 (see Fig. ) can include the application of an adhesive layer 16 to the X-ray window 14. The application of the adhesive layer 16 can be carried out in the vacuum of a vacuum chamber. Step 150 (see Fig. Step 150 can include applying a mask 41 to the adhesive layer 16 and subsequently etching the adhesive layer 16 within an opening 42 of the mask 41. Step 150 can follow step 140. The vacuum chamber can be opened after step 140 and closed before etching the adhesive layer 16, and a vacuum can be applied. Step 160 (see Fig. Step 160 can involve applying a target 17 to the middle adhesive layer 16 within the opening 42 of the mask 41 and subsequently removing the mask 41. Step 160 can follow step 150. Steps 150 and 160 can be performed without opening the vacuum chamber or breaking the vacuum between these steps 150 and 160. Step 170 (see Fig. Step 170 can include applying a second mask 41s to the target 17, applying a conductive layer 18 to the outer adhesive layer 16 surrounding the target 17, and subsequently removing the second mask 41s. Step 170 can follow step 160. Step 180 (see Fig. ) can include the fastening of the X-ray window 14 to a flange 19 of an anode 12 for an X-ray tube 70 by means of a sealing layer 13. Step 180 can follow step 160 or step 170.

[0066] This method can lead to different thicknesses of the outer adhesive layer 16o in relation to the middle adhesive layer 16c (Ts ≠ Tt, Tg ≠ Tt). X-ray tube 190

[0067] As in the Fig. As shown, the target 17 can be separated from the sealing layer 13 by a gap 21. The adhesive layer 16 can span the gap 21 between the target 17 and the sealing layer 13. The adhesive layer 16 can have a uniform thickness (within normal manufacturing tolerances) over an area of ​​the X-ray window 14. A conductive layer 18 can be located on the adhesive layer 16 in the gap 21.

[0068] A sequence of layers on an outer ring of the X-ray window 14 can consist of, or include, the X-ray window 14, the adhesive layer 16, the conductive layer 18, the sealing layer 13, and the flange 19. A sequence of layers in the center of the X-ray window 14 can consist of, or include, the X-ray window 14, the adhesive layer 16, and the target 17. The X-ray tube 190 is preferably used for fewer layers in the center of the X-ray window 14. A disadvantage of the X-ray tube 190 is its increased manufacturing complexity.

[0069] In the following procedure for assembling an X-ray window 14 with a target 17, the steps can be performed in the described order. Components can have the properties described above. Sputtering can be used for the application steps. The procedure can include some or all of the following steps: Step 210 (see Fig. ) can include the application of an adhesive layer 16 to a surface of the X-ray window 14. Step 220 (see Fig. The process can include applying a mask 41 to the adhesive layer 16. The mask 41 can have an opening 42 that exposes the adhesive layer 16. The opening 42 can be located in the center of the mask 41. The mask 41 can be applied without opening the vacuum chamber. Step 230 (see Fig. ) can include applying a target 17 to the adhesive layer 16 inside the opening 42 of the mask 41 and subsequently removing the mask 41. Step 240 (see Fig. ) can include applying a second mask 41s to the target 17, applying a conductive layer 18 to the adhesive layer 16 on an outer circumference of the target 17 and subsequently removing the second mask 41s. Step 250 (see Fig. ) can follow step 230 or step 240. In step 250, the X-ray window 14 can be hermetically sealed to a flange 19 of the anode 12 by a sealing layer 13. The adhesive layer 16 can be located between the sealing layer 13 and the X-ray window 14.

[0070] The adhesive layer 16 can be used to bond the sealing layer 13 to the X-ray window 14. Therefore, step 210 can involve applying the adhesive layer 16 over most or all of the surface of the X-ray window 14.

[0071] It may be useful to maintain a certain distance between the target 17 and the sealing layer 13 in order to avoid interdiffusion of these materials.

[0072] The mask 41 from step 220 can limit the application of the target 17 to the center of the adhesive layer 16. X-ray tube 260

[0073] As seen on the X-ray tube 260 in the Fig. As shown, a gap 21 can be present between the flange 19 and the adhesive layer 16, as well as between the flange 19 and the target 17. This gap 21 can help prevent interdiffusion of materials from the target 17 and the adhesive layer 16 with the sealing layer 13. If the X-ray window 14 is electrically insulating, a conductive layer 18 can establish an electrical connection between the target 17 and the anode 12. The adhesive layer 16 can be applied in a single step, simplifying the manufacturing process.

[0074] One disadvantage of this X-ray tube 260 is the difficult and costly application of the conductive layer 18 to the X-ray window 14.

[0075] Another disadvantage of this X-ray tube 260 is the difficulty of bonding the sealing layer 13 to the X-ray window 14. This difficulty can be overcome by using titanium in the sealing layer 13. Titanium has a strong tendency to interdiffusion with the material of the target 17 and the adhesive layer 16; however, the gap 21 can prevent this interdiffusion. Through this gap 21, the adhesive layer 16 and / or the target 17 can contain titanium.

[0076] In the following procedure for assembling an X-ray window 14 with a target 17, the steps can be carried out in the described order.

[0077] Components can have the properties described above. Sputtering can be used for the application steps. The process can include some or all of the following steps: Step 280 (see Fig. The process can include applying an adhesive layer 16 to an X-ray window 14 and applying a target 17 to the adhesive layer 16. The adhesive layer 16 and the target 17 can be applied in the center of the X-ray window 14.

[0078] The adhesive layer 16 can be narrow, as in the Fig. shown, or the adhesive layer 16 can be wide, as shown in Fig. The clamping at an outer edge of the X-ray window 14 can prevent the adhesive layer 16 from being as wide as the X-ray window 14.

[0079] A gap 21 in which the adhesive layer 16, the target 17, or both are not desired can be covered during application. Alternatively, a desired area in which the adhesive layer 16, the target 17, or both are to remain can be covered after application, and an unmasked area can be removed by etching.

[0080] Step 290 (see Fig. ) can include the application of a conductive layer 18 to the X-ray window 14 in the slit 21. In Fig. A mask 301 with openings 302 is shown, in which the conductive layer 18 can be applied. The size of the opening can be changed to shape the conductive layer 18 as shown in Fig. depicted.

[0081] Another step (see Fig. ) can include mounting the X-ray window 14 to a flange 19 of an anode 12 for an X-ray tube 260. This step can include hermetically sealing the X-ray window 14 to the flange 19 by means of a sealing layer 13. Example 310

[0082] As in the Fig. As shown, a stack of layers in the middle of the X-ray window 14 can contain the following layers in the following order: the X-ray window 14, a first adhesive layer 16a, a conductive layer 18, a second adhesive layer 16b and finally a target 17.

[0083] The sequence of layers on an outer ring of the X-ray window 14 can include the following layers in the following order: the X-ray window 14, the first adhesive layer 16a, the conductive layer 18, the sealing layer 13 and finally the flange 19.

[0084] The first adhesive layer 16a can help the conductive layer 18 adhere to the X-ray window 14. The second adhesive layer 16b can help the target 17 adhere.

[0085] The first adhesive layer 16a and the conductive layer 18 can extend across the X-ray window 14. The second adhesive layer 16b and the target 17 can be applied in the center of the X-ray window 14, with a gap 21 surrounding these layers 16b and 17. The first adhesive layer 16a and the conductive layer 18 can span the gap 21 between the target 17 and the sealing layer 13.

[0086] Applying the first adhesive layer 16a and the conductive layer 18 over most or all of the surface of the X-ray window 14 can simplify the fabrication. A disadvantage of this example is that the X-rays generated in the target 17 would have to pass through two adhesive layers 16a and 16b as well as the conductive layer 18.

[0087] In the following procedure for assembling an X-ray window 14 with a target 17, the steps can be performed in the described order. Components can have the properties described above. Sputtering can be used for the application steps. The procedure can include some or all of the following steps: Step 330 (see Fig. ) can include the application of a first adhesive layer 16a to an X-ray window 14. Step 340 (see Fig. ) can include the application of a conductive layer 18 to the first adhesive layer 16a. Step 340 can follow step 330. Step 350 (see Fig. ) can include applying a mask 41 to the conductive layer 18 and subsequently applying a second adhesive layer 16b to the conductive layer 18 in an opening 42 of the mask 41. Step 350 can follow step 340. Step 360 (see Fig. ) can include applying a target 17 to the second adhesive layer 16b in the opening 42 of the mask 41 and subsequently removing the mask 41. Step 360 can follow step 350.

[0088] In a further step (see Fig. The X-ray window 14 can be hermetically sealed to a flange 19 of the anode 12 by a sealing layer 13. This step can follow step 360.

Claims

[1] Method for assembling an X-ray window (14) with a target (17), the method comprising: Applying an adhesive layer (16) to the X-ray window (14); Deposition of a target (17) on the adhesive layer (16) with a gap (21) on the X-ray window (14) that is free of the target (17) and surrounds the target (17), wherein the target (17) is configured to generate X-rays in response to incident electrons from an electron emitter (11e) and the target (17) contains a noble metal; Applying a conductive layer (18) to the X-ray window (14) in the slit (21), wherein the conductive layer (18) borders the target (17), wherein an area on the target (17) is free of the conductive layer (18), and wherein the conductive layer (18) is electrically conductive; and Mounting the X-ray window (14) on a flange (19) of an anode (12) for an X-ray tube (10, 80, 190, 260, 310) by means of a sealing layer (13), wherein the flange (19) encloses an opening (22), the X-ray window (14) spans the opening (22) and the target (17) is spaced apart from the flange (19) by the gap (21). [2] Method according to claim 1, wherein: the application of the adhesive layer (16) includes the application with the gap (21) on the X-ray window (14) which is free of the adhesive layer (16); and the application of the conductive layer (18) includes the application of the conductive layer (18) to ≥5% and ≤50% of the gap (21). [3] Method according to claim 2, wherein: the conductive layer (18) contains tungsten, molybdenum or both; and the sealing layer (13) comprises silver, copper and titanium. [4] Method according to claim 1, wherein: the adhesive layer (16) extends into the gap (21); and the conductive layer (18) covers ≥75% of the adhesive layer (16) in the gap (21). [5] Method according to claim 4, wherein the adhesive layer (16) spans and covers the gap (21). [6] Method according to claim 5, wherein the adhesive layer (16) contains chromium. [7] Method according to claim 1, wherein the area on the target (17) which is free from the conductive layer (18) is ≥75% of an area of ​​the target (17) opposite the X-ray window (14). [8] Method according to claim 1, wherein the adhesive layer (16) spans the gap (21) between the target (17) and the sealing layer (13) and the adhesive layer (16) is adjacent to the sealing layer (13). [9] Method according to claim 1, wherein the adhesive layer (16) is located between the sealing layer (13) and the X-ray window (14); and 1.3*Ts ≤ Tt, where Ts is a maximum thickness of the adhesive layer (16) between the sealing layer (13) and the X-ray window (14) and Tt is a minimum thickness of the adhesive layer (16) between the target (17) and the X-ray window (14). [10] Method according to claim 9, wherein 1.3 *Tg ≤ Tt and Tg is the maximum thickness of the adhesive layer (16) in the gap (21).

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