DEVICE AND METHOD FOR SELECTIVE VAPOR COATING OF A SUBSTRATE

Abstract

A fixture (1) for use in a coating operation, preferably in the shape of a carousel rotatable around a central axis (L), comprising a support structure (5) to which a shield is fixed, the shield has a number of retainer openings (19), each designed that way that through each of the retainer openings (19) an object to be treated can be stuck so that a first portion of each object extends from the shield into the coating deposition area, whereas a second portion of each object extends from the shield into a shielded area where no coating deposition can take place, whereas the said shielded area is a common hollow space (13) which jointly accommodates a plurality of second portions.

Claims

1. A fixture for use in a coating operation, in the shape of a carousel rotatable around a central axis, comprising: a support structure to which a shield is fixed, wherein the shield has a plurality of retainer openings, each designed such that through each of the retainer openings an object to be treated can be stuck so that a first portion of each object extends from the shield into a coating deposition area, and a second portion of each object extends from the shield into a shielded area where no coating deposition can take place, wherein said shielded area is a common hollow space which jointly accommodates a plurality of second portions.

2. The fixture according to claim 1, wherein the support structure possesses a central tube that is surrounded by the shield, and the central tube and the shield together confine the shielded area in the shape of the common hollow space.

3. The fixture according to claim 2, wherein the support structure comprises a first flange and a second flange extending from the central tube, said first and second flanges forming a base for the attachment of the shield or shielding plates.

4. The fixture according to claim 3, wherein the first and second flanges are interconnected by support bars that directly contact the shield.

5. The fixture according to claim 1, wherein the shield is formed by a plurality of shielding plates, with lateral flanges of directly neighbored shielding plates sealing togetherwith or without involvement of a support barthe shielded area in the shape of the common hollow space when the shielding plates are in position ready for deposition operation.

6. The fixture according to claim 1, wherein the shielding plates are flat panels.

7. The fixture according to claim 3, wherein a circumference of said first and second flanges forms a polygon with plurality of flat bases for the attachment of the shielding plates.

8. The fixture according to claim 1, wherein the shield comprises a base carrier with a plurality of windows and a plurality of adapter plates mounted to the base carrier to close the windows without closing the retainer openings provided in the adapter plates.

9. The fixture according to claim 8, wherein an adapter plate can be fixed to the base plate in different rotary positions, and an outer circumference of the adapter plate is round for that purpose.

10. The fixture according to claim 8, wherein a spring element is assigned to a retainer opening, and the spring element is designed to immobilize the object stuck through the retainer opening.

11. The fixture according to claim 10, wherein the spring element is anchored to the base carrier, at least when tensioned, such that the spring element contributes to immobilizing the object to be coated as well as the adapter plate relative to the base carrier.

12. The fixture according to claim 1, wherein the shield or a shielding plate or an adapter plate of the shield or shielding plate is a sandwich of a front plate forming a bezel portion of each retainer opening and a back plate forming a retaining portion of each retainer opening, with a contact area between the front plate and the back plate being sealed, so that no debris or cleaning agents can intrude between the front and back plates.

13. A physical vapor deposition coating machine comprising the fixture according to claim 1.

14. A method for physical vapor deposition coating, comprising: using the fixture according to claim 1 for holding the substrates; sticking the substrates to be coated through shielding plates; subjecting the substrates to a cleaning process while the substrates are retained by said shielding plates; mounting the shielding plates with the substrates to said fixture, which in turn is or will be positioned in the deposition chamber, and carrying out the physical vapor deposition.

Description

THE LIST OF FIGURES

[0039] FIG. 1 shows a shielding plate according to the state of the art.

[0040] FIG. 2 shows a deposition chamber equipped with a fixture according to the state of the art.

[0041] FIG. 3 shows an embodiment of a support structure according to the invention without a shield or shielding plates.

[0042] FIG. 4 shows the support structure according FIG. 3 with one exemplary shielding plate going to be mounted.

[0043] FIG. 5 shows the support structure according FIG. 3 fully equipped with shielding plates, i. e. in condition ready for deposition of a coating.

[0044] FIG. 6 shows an enlarged view to the backside of a shielding plate as carried by the support structure according to FIG. 5.

[0045] FIG. 7 shows an enlarged view to the upper portion of the front-side of the shielding plate shown by FIG. 6.

[0046] FIG. 8 shows a view to an alternative second embodiment of a shielding plate according to the invention.

THE FIRST PREFERRED EMBODIMENT

Overview

[0047] FIGS. 3 to 5 give a complete overview over an inventive fixture 1.

[0048] The fixture 1 carries a shield being composed here of a number of shielding plates 2. Each of the shielding plates 2 carriespreferablya number of turbine blades 3. From each of the turbine blades 3 only the true air foil 4 is visible, which forms the so-called first portion and extends in radial outward direction into the deposition chamber, ready for coating by deposition.

[0049] Not shown by FIGS. 3 to 5 are the sockets of the turbine blades 3, which form the so-called second portions that are shielded against deposition. This fixture 1 carrying the substrates like turbine blades 3 is positioned in the deposition chamber of a deposition machine which may be designed and work in the same manner as already explained by means of FIG. 2 for the state of the art.

[0050] The Support Structure

[0051] FIG. 3 shows the support structure 5 to which the shielding plates 2 can be attached.

[0052] The support structure 5 is preferably designed as a rotatable carousel. The support structure 5 comprises a central tube 6. Normally, the central tube 6 has a completely closed circumferential surface, at least essentially. Small local holes, as used for fixing purposes, are not detrimental.

[0053] Preferably on the inside of the central tube, the bearings and maybe the drive for rotating the whole fixture 1 around its longitudinal axis L are accommodated. That way the bearings and the drive, if any, are protected from detrimental deposition.

[0054] From the central tube 6 at least a first flange 7 and a second flange 8 extend in radial outward direction. The flanges 7, 8 are attached to the opposite ends of the tube 6.

[0055] Said flanges 7, 8 could be designed as closed plates, however, that is not mandatory. In this particular case the flanges 7, 8 are designed with windows 11 in it in order to save material and weight. The existence of such windows 11 is not detrimental as long as they are positioned out of the intrusion area of the vapor.

[0056] As one can see, the circumference of each flange 7, 8 is preferably designed as a polygon or ideally as a hexagon or an octagon. Why this is preferred will become clear hereinafter.

[0057] The flanges 7 and 8 may be interconnected by means of support bars 9. Normally, the support bars contact the shielding plates when those are put into their working position that means ready for deposition. Preferably together with the support bars 9 the flat surfaces 12 at the circumference of the flanges 7, 8 form in most cases a rectangular frame for receiving the backside of a shielding plate 2 in a tightening manner. The expression tightening manner does not mean a hermetic tightness. A tightness against intrusion of vapor in radial direction is sufficient. Even a slot can provide for such a tightness if it forms a kind of labyrinth blocking the straight path in radial direction.

[0058] As one can see from FIG. 3 or 4, one or more intermediate supports 10 can be provided. The intermediate supports avoid that the support bars 9 are detrimentally prone to vibration. The intermediate supports 10 can be designed in a rod-like manner, as shown by FIG. 3 or 4. Such is preferred.

[0059] Alternatively, the intermediate supports 10 could be designed as continuous plates, even without windows in it. That way they would divide the hollow space 13 in a bulkhead manner intofor exampletwo subsections, each accommodating a number of second portions. Such is not shown here and such is not preferred but mentioned to avoid circumvention.

[0060] As can be seen best by comparison of FIGS. 3 and 4, the fixture 1 may be equipped with radially protruding foot plates 14a and maybe with comparable head plates 14b, too. Said plates, if any, may contribute to fixing or positioning of the shielding plates 2.

[0061] As a material for the construction of the support structure 5 preferably an austenitic steel is used, for example like EN 1.4301, or a corrosion resistant ferritic steel, as EN 1.4622, for example.

[0062] The Joint Hollow Space being Shielded

[0063] In the light of what has been explained before, one recognizes that the shielding plates 2 closely grouped in circumferential direction around the central tube 6 confines together with the central tube 6 (in the area between the flanges 7, 8) a joint hollow space 13. This hollow space is here the radial interspace between the shielding plates 2 and the central tube 6.

[0064] The said hollow space is shielded against intrusion of vapor.

[0065] It jointly accommodates a plurality or, as here, all second portions of the substrates under processingin case of turbine blades all their sockets which are not allowed to receive a coating.

[0066] Preferably said hollow spaceallocated between the two said flanges 7, 8has a volume of more than 0.01 m.sup.3. In most cases the volume is hollow space in the range between 0.03 m.sup.3 to 1 m.sup.3. Typically the hollow space has a (fully or essentially) tubular shape, with the imagined wall of said tube, which preferably has a radial thickness between 0.08 m and 0.3 m everywhere, forms the hollow space.

[0067] The Design of the Shield

[0068] As already mentioned above, the shield could theoretically be one single jacket that is wrapped with the required radial distance around the central tube 6.

[0069] However, such a design would be inconvenient for most application purposes. For that reason, it is preferred that a number of shielding plates 2 form together the shield in the shape of a jacket which is wrapped around the central tube 6 as mentioned above.

[0070] Preferably, each of the shielding plates 2 is designed as disclosed by FIG. 6. FIG. 7 illustrates how a turbine blade 3, forming the substrate to be coated here, is fixed to such a shielding plate 2 ready for coating.

[0071] As easily can be seen, each shielding plate 2 processes preferably between 3 and 15 retainer openings 19. Each of the retainer openings 19 is designed in such a way that the substrate to be coated can be stuck through the retainer opening 19, see FIG. 7.

[0072] In most cases such a shielding plate 2 is a (fully or essentially) flat plate with two main surfaces 15, two side surfaces 16 and two forehead surfaces 17. Typically the surface area of each of the two main surfaces 15 is at least seven times bigger than the surface area of each of the side surfaces 16 and the forehead surfaces 17. Typically, the surface area of each of the two side surfaces 16 is at least 5 times bigger than the surface area 17 of each of the forehead surfaces. This design awards a strip like appearance to the shielding plate.

[0073] Preferably, each of the shielding plates 2 is formed by a sandwich of a holding plate 18 and a bezel plate 21 which lie upon another with one of their main surfaces 15. This can best seen in FIG. 7.

[0074] The holding plate 18 carries, individually for each substrate to be coated, a retainer opening 19. The retainer opening 19 has the shape of the window going through the holding plate 18. The retainer opening 19 processes side walls 20 custom-made for the individual substrates to be coated. The side walls 20 embrace the second portion of the substrate to be coated in a form-fit manner. That is a precondition for holding the substrate to be coated in an exactly defined position.

[0075] As being self-evident from FIG. 6, the window going through the holding plate 18 is not closed by a cover but remains open toward the inventive single hollow space.

[0076] The bezel plate 21 carries, individually for each substrate to be coated, a window that forms a bezel. For this purpose said window is smaller than the window going through the holding plate 18. Each of said windows of the bezel plate 21 is positioned that way that it is aligned with the assigned window going through the holding plate 18. The bezel plate 21 shades the second portion against the access by the vapor being generated in the process chamber.

[0077] In many cases the holding plate 18 and the bezel plate 21 are tightened against one another. That makes it possible to use the shielding plate 2 not only during the vapor deposition.

[0078] Instead, such a shielding plate 2 can already be used during the preparation of the substrates, in order to firmly hold it for example during sandblasting. If the two plates are tightened against one another, there is no risk that residual sand blasting material may be unintentionally conveyed into the deposition chamber where it would be detrimental.

[0079] Said tightening preferably is realized by soldering said two plates together, in some cases over the whole surface area of the two contacting main surfaces of the plates. A preferred solder for soldering is an Ag-based solder or another solder that is thermally stable even under load with the temperatures of more than 500 C. and that is corrosion resistant, too.

[0080] In order to immobilize the second portion of the substrate to be coated within the window of the holding plate 18, a spring element 22 is provided. Preferably, an own spring element 22 is assigned to each of said windows in the holding plate 18.

[0081] As easily can be seen in FIG. 6, the spring element 22 is configured here as a leaf spring that presses the second portion of substrate in direction perpendicular to the main surface 15 of the shielding plate.

[0082] Preferably, the spring element 22 has a V-shaped main portion 23 with two hooked legs 24 extending therefrom. The V-shaped main portion 23 presses against the second portion of the substrate. Each of the hooked legs 24 can be snapped into a fixation hole 25 provided for that purpose in the holding plate 18 at at least two sides of each window therein. As one can see, each fixation hole 25 is covered by the bezel plate 21 against direct access of by vapor in the deposition chamber.

[0083] As an alternative for said fixation holes 25 lashes can be provided that extend from the surface 15 of the shielding plate. Such lashes will be explained in greater detail later. However, for cost reasons the fixation holes are preferred, because they can easily be punched out, for example.

[0084] It has turned out that it is a particular advantage to manufacture the springs out of a steel that is creep-resistant and/or high-temperature-resistant against temperatures above 500 C. An ideal material is Nimonic 90.

[0085] Preferably, the holding plate 18 is equipped with form-fit elements for detachably fixing the shielding plate 2 to the support structure 5.

[0086] One of these form-fit elements, preferably the upper one, may be embodied as a C-shaped hanger claw or as a T-shaped protrusion, as shown by FIGS. 6 and 7. The T-shaped protrusion, too, can be hooked into the support structure. The other one of these form-fit elements, preferably the lower one, can be embodied as a tongue-like protrusion for snap-latching the shielding plate 2 to the support structure 5 or for clicking it to the support structure 5, see FIG. 6.

[0087] Preferably, the bezel plate 21 itself does not embody said hanger claw, said T-shaped protrusion or said tongue-like protrusion, see FIG. 7.

[0088] In regard to the material used for the shield or shielding plates 2 it applies what has been said above in regard to the support structure 5.

Another Preferred Embodiment

[0089] Except for the differences explained hereinafter, the second preferred embodiment is identical to the first preferred embodiment explained above. For that reason, all of the above explanations for the first embodiment apply to the second embodiment, too, as long as the special features described hereinafter do not withstand.

[0090] The striking difference of the second preferred embodiment is that for this embodiment more versatile shielding plates 2 are used, as shown by FIG. 8.

[0091] An according shielding plate 2 comprises a base carrier 26. The base carrier 26 carries a number of windows. Moreover, a number of adapter plates 27 is mounted to the base carrier 26 in order to close the said windows partially. The adapter plates a preferably mounted on the shielded backside of the base carrier. The only breakthrough remaining hereinafter in the area of the aforementioned window is the retainer opening 19 provided in each of the adapter plates 27.

[0092] So the advantage is that one and the same carrier 26 can be used for coating very different substrates.

[0093] In order to customize the carrier 26 to the different substrates to be coated, nothing else is required than accordingly customized adapter plates. This drastically reduces the manufacturing costs as well as the costs for storingsince no complete shielding plates 2 have to be stored anymore but only the much smaller adapter plates 27.

[0094] Preferably, one single adapter plate 27 is assigned to each individual substrate.

[0095] The adapter plates 27 themselves are designed in regard to their retainer opening 19 preferably according to what has been described above.

[0096] It is preferred here, too, to manufacture the adapter plates as a sandwich, preferably with two layers only. Such a sandwich is composed of a front plate that forms a bezel plate and a back plate that forms a carrier plateas already described for the first embodiment. The carrier plate forms sidewalls which accommodate the second portion in form-fit manner. Preferably, the bezel plate and the carrier plate are tightened against each other, in most cases by soldering as explained above.

[0097] Preferably, the outer circumference of the adapter plates 27 is designed that way, that the adapter plates 27 can be mounted to the base carrier 26 in different rotary positions, that means for example in 6 o'clock position, 9 o'clock position or in 12 o'clock position, all related to a line orthogonal to the window in the base carrier 26.

[0098] That way it is possible to tune the orientation of the substrate's first portion within the deposition chamber as it is needed for the individual casethat means in order to obtain an optimized coating result.

[0099] The most preferred variant of the adapter plates 27 has a circular outer circumference, not shown by the Figs. Such an adapter plate can be mounted to the base carrier in every rotary position necessary. Alternatively, other adapter plates with quadratic, triangular, hexagonal or polygonal circumference are possible. Such adapter plates can also be mounted in different rotary positions, even if not so versatile.

[0100] The adapter plate 27 shown by FIG. 8 has a rectangular circumference. For that reason, it always has to be mounted in the same position.

[0101] In order to support the positioning and the fixing of the adapter plates 27, a number of lashes 28 are provided on the base carrier 26. Preferably, the lashes 28 guide two opposite circumferential sides of an adapter plate 27 in a form-fit manner. That way it is made sure that the positioning of each adapter plate 27 is precise.

[0102] Each of the lashes 28 serves for anchoring the spring element 22. Preferably, the spring element 22 is designed as already explained in connection with the first embodiment. If such a spring element 22 is used, every leg 24 of the spring element 22 can be nested into one lash 28.

[0103] That way the spring element 22 exerts pressure to the second portion of the substrate to be coated. The second portion of the substrate to be coated is that way pressed into the opening of the adapter plate 27. At the same time, the assembly of the adapter plate 27 and the substrate to be coated are pressed against the base carrier 26, altogether.

[0104] Preferably, each adapter plate 27 is equipped with two lateral recesses 29. Each recess 29 accommodates a part of a leg of the spring element 22, when mounted. That way the adapter plate 27 is secured by additional form-fit against slipping out of the base carrier 26 or (in this case) against slipping out of the guidance provided by the lashes 28.

[0105] As it is clearly visible when regarding FIG. 8, the big advantage of this design is that nothing else is required for synchronously fixing the substrate to be coated and the adapter plate than the tensioning of one single spring element. More exactly said, nothing else is necessary to fix the whole assembly than the nesting of the two legs of the leaf spring element 22 used here.

[0106] For sake of completeness it has to be said that it is an option to use here, too, the fixation holes 25 known from the first embodiment, instead of the lashes 28.

LIST OF REFERENCE NUMBERS

[0107] 1 fixture [0108] 2 shielding plate [0109] 3 turbine blade [0110] 4 air blade/air blade portion of the turbine blade [0111] 5 support structure [0112] 6 central tube [0113] 7 first flange [0114] 8 second flange [0115] 9 support bar [0116] 10 intermediate support [0117] 11 window in the flange [0118] 12 flat surface of a flange [0119] 13 hollow space [0120] 14a foot plate [0121] 14b head plate [0122] 15 main surface of the shielding plate [0123] 16 side surfaces of the shielding plate [0124] 17 forehead surfaces of the shielding plate [0125] 18 holding plate [0126] 19 retainer opening [0127] 20 side walls of the compartment [0128] 21 bezel plate [0129] 22 spring element [0130] 23 main portion [0131] 24 hooked legs [0132] 25 fixation hole [0133] 26 base carrier [0134] 27 adapter plate [0135] 28 lash [0136] 29 spring receiving recess in an adapter plate [0137] L longitudinal axis