Plasma coating device and method for plasma coating of a substrate

Abstract

The invention relates to a plasma coating device ( 10 ) and a method for homogenous coating of a substrate ( 12 ). It comprises a particle reservoir ( 14 ), a dosing device ( 16 ) for dosing the particles ( 15 ) contained in the particle reservoir ( 14 ), a processing chamber ( 20 ) and a transport line ( 18 ) to convey particles ( 15 ) into the processing chamber ( 20 ). The processing chamber pressure (P 1 ) in the processing chamber ( 20 ) is lower than the particle reservoir pressure (P 2 ) in the particle reservoir ( 14 ).

What is claimed is: 
     
         1 . A plasma coating device for coating a substrate with particles, the device comprising:
 a particle reservoir;   a dosing device for dosing the particles stored in the particle reservoir;   an all-round closed processing chamber;   at least one transport line from the particle reservoir to the processing chamber;   a suction pump being connected with the processing chamber such that a pressure gradient between the processing chamber and the particle reservoir is setable in such a way that there is a processing chamber pressure in the processing chamber and a particle reservoir pressure in the particle reservoir, wherein the processing chamber pressure is lower than the particle reservoir pressure; and,   a plasma coating torch within the processing chamber receives at a constant conveying rate the particles from the particle reservoir, wherein the constant conveying rate is accurately adjustable by means of the transport line and mechanically or pneumatically generated particle aggregations within the transport line are avoided.   
     
     
         2 . The plasma coating device as recited in  claim 1 , wherein a dosing chamber accommodates the dosing device which is connected with the processing chamber via the transport line. 
     
     
         3 . The plasma coating device as recited in  claim 2 , wherein the processing chamber is functionally separated from the dosing chamber. 
     
     
         4 . The plasma coating device as recited in  claim 1 , wherein a suction line is connected to the processing chamber and to the suction pump. 
     
     
         5 . The plasma coating device as recited in  claim 1 , wherein a throttle valve is arranged upstream of the suction pump and at least one filter is arranged between the throttle valve and the suction pump. 
     
     
         6 . The plasma coating device as recited in  claim 1 , wherein a pressure difference between the particle reservoir pressure and the processing chamber pressure is between 50 mbar and 1000 mbar. 
     
     
         7 . The plasma coating device as recited in  claim 6 , wherein the pressure difference is set at 200 mbar. 
     
     
         8 . The plasma coating device as recited in  claim 1 , wherein the particle reservoir pressure is between 900 mbar and 1500 mbar. 
     
     
         9 . The plasma coating device as recited in  claim 1 , wherein the process chamber pressure is at most 1013 mbar. 
     
     
         10 . The plasma coating device as recited in  claim 9 , wherein the process chamber pressure is lower than 500 mbar. 
     
     
         11 . The plasma coating device as recited in  claim 10 , wherein the process chamber pressure is 30 mbar. 
     
     
         12 . The plasma coating device as recited in  claim 1 , wherein the dosing device has a movable suction lance which protrudes into the particle reservoir and is connected with the transport line. 
     
     
         13 . The plasma coating device as recited in  claim 1 , wherein an additional supporting pump is assigned to and acts on the dosing chamber. 
     
     
         14 . The plasma coating device as recited in  claim 1 , wherein a transport line element for stabilization of the pressure gradient is provided in the transport line. 
     
     
         15 . The plasma coating device as recited in  claim 14 , wherein the transport line element is a supporting pump or a throttle. 
     
     
         16 . A method for plasma coating of a substrate, the method comprising the steps of:
 extracting in a regulated manner particles from a particle reservoir with a dosing device by means of a movable suction lance;   supplying the particles via a transport line to a processing chamber, in which a plasma coating torch is provided; and,   setting a pressure gradient between the processing chamber and the particle reservoir by means of a suction pump connected to the processing chamber such that the pressure gradient determines a delivery rate of particles.   
     
     
         17 . The method for plasma coating a substrate as recited in  claim 16 , wherein the pressure gradient is adjusted via a suction power generated by the suction pump. 
     
     
         18 . The method for plasma coating a substrate recited in  claim 16 , wherein the pressure gradient is adjusted by additional elements within a transport line wherein the additional elements are formed by a throttle valve and/or a pressure pump and/or a transport line element. 
     
     
         19 . A plasma coating device for coating a substrate with particles, the device comprising:
 a particle reservoir;   a dosing device with a movable suction lance which protrudes into the particle reservoir for dosing the particles stored in the particle reservoir;   an all-round closed processing chamber;   at least one transport line from the particle reservoir to the processing chamber;   a suction pump being connected with the processing chamber via a suction line such that a pressure gradient between the processing chamber and the particle reservoir is setable in such a way that there is a processing chamber pressure in the processing chamber and a particle reservoir pressure in the particle reservoir, wherein the processing chamber pressure is lower than the particle reservoir pressure; and,   a plasma coating torch within the processing chamber receives at a constant conveying rate the particles from the particle reservoir, wherein the constant conveying rate is accurately adjustable by means of the transport line and mechanically or pneumatically generated particle aggregations within the transport line are avoided.   
     
     
         20 . The plasma coating device as recited in  claim 19  further comprising an additional supporting pump assigned to and acting on the dosing chamber. 
     
     
         21 . The plasma coating device as recited in  claim 19  further comprising a transport line element for stabilizing the pressure gradient in the transport line.