Patent Application
20120193226
The present disclosure relates to a steered arc physical vapor deposition system, and more particularly to a cylindrical post cathode for a steered arc physical vapor deposition system.
Physical vapor deposition (PVD) systems are utilized in cathodic arc coating to vaporize a material and deposit that material on a piece, thereby coating the piece with a thin layer of the material. PVD systems use a cathode/anode arrangement where the cathode includes an evaporation surface made from the coating material. The cathode and the anode of the PVD system are contained within a vacuum chamber. A power source is connected to the cathode and the anode with the positive connection of the power source connected to the anode and the negative connection of the power source connected to the cathode. By connecting the positive power connection to the anode and the negative power connection to the cathode, a charge disparity between the anode and the cathode is generated.
The charge disparity causes an electrical arc to jump between the cathode and the anode. In standard PVD systems, the arc location is random over the surface of the cathode. The arcing causes the evaporation surface of the cathode to vaporize at the point where the arc occurred. The vaporized cathode material then coats the piece contained in the vacuum chamber.
In order to control the density and distribution of the coating, steered arc systems control the location of the arc on the cathode's surface by manipulating magnetic fields.
Disclosed is a steered arc PVD assembly having a vacuum chamber, a post cathode inside the vacuum chamber, a magnet suspended within the post cathode, and a power source capable of providing a first charge to the post cathode and a second charge to an anode. The first charge and the second charge are opposite charges.
Also disclosed is a post cathode having a tube, and a ring magnet disposed within the tube. The ring magnet has an axis aligned with an axis of the tube. A side wall of the tube is an evaporation source material.
The disclosure can be further understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:
When the PVD system 10 is operating, the magnetic field generated by the magnet 60 forces the arc to occur at an intersection of the magnetic field and the surface of the cathode 20, thereby influencing where a vaporized coating will settle on a part 50. The magnet 60 is suspended within the post cathode 20 on the shaft 70. The shaft 70 moves the magnet 60 along an axis defined by the shaft 70, the magnet 60, and the post cathode 20. Shifting the position of the magnet 60, provides for positioning of the arc for controlling vapor deposition. The shaft 70 extends out of the vacuum chamber 30 and is connected to an actuation device 15. While the magnet 60 is described herein as a single magnet 60, it is understood that a magnet assembly, or some combination of permanent magnets and electromagnets, could also be used with minimal modification to the disclosure.
The cylindrical post cathode 110 has a top cap portion 112, a bottom cap portion 114 and a side wall portion 116. The side wall portion 116 is an evaporation source material that is evaporated during a cathodic arc. The vapor is deposited on an adjacent part 180 to provide a thin coating of the source material on the workpiece.
Alternate PVD systems using cylindrical post cathodes 110 may not require a cooling fluid. These PVD systems do not include the cooling fluid inlet and outlet 150, 152, with all other features being substantially the same as the above described example. Another example PVD system replaces the camshaft actuation system 120 with a linear actuator, to provide desired precision and accuracy over movement and positioning of the magnet 172.
A fluid actuating system can be implemented as an alternate to the above described mechanical actuation systems for adjusting the location of the magnet 70. Referring to
The magnet 260 is slidably mounted on the cooling shaft 230. The axial position of the magnet 260 is adjusted by altering the pressures of the cooling fluid 240 above and below the magnet 260. By increasing the pressure below the magnet 260, relative to the pressure above the magnet 260, the magnet 260 moves axially up along the cooling shaft 230. Likewise, decreasing the pressure below the magnet 260, relative to the pressure above the magnet 260, causes the magnet 260 to be moved axially down along the cooling shaft 230. In this way, a controller 22 (
Returning to the example of
Although an example embodiment has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of the claims. For that reason, the following claims should be studied to determine their true scope and content.
