Application of Diamond-like Carbon Films to Spacer Tools for Electron Guns of Cathode Ray Tube (CRT)

Youngha Jun, Jun-Youp Choi, Kwang-Ryeol Lee, Bong-Kyo Jeong, Soo-Kun Kwon and Cheol-Ho Hwang

The surface properties of spacer tools, which are sliding between grid plates of electron gun for cathode ray tube (CRT) to control the space gap between the plates, are very crucial.  The scratches can be made by the friction on the surface of plates when these tools are sliding in and out between the plates. Since the gap and surface scratch of the grid plates play major roles in the performance of the electron gun and the electron beam comming out from the cathode of CRT, it is very important to keep the surface of tools smooth and clean.  Furthermore, the productivity of the electron gun assembly process is significantly dependent on the friction between the tool and the plate surface.  Diamond-like carbon (DLC) film of 800 nm thickness was deposited on both surfaces of the spacer tools to improve the tribological properties and wear resistance.  The film was deposited by plasma enhanced CVD method using 13.56 MHz radio frequency with benzene.  Si intermediate layer was used to improve the adhesion of DLC film. Process parameters for Ar cleaning and Si intermediate layer were optimized in the view point of adhesion improvement of DLC films to tool steel substrate.  The field test in the electron gun assembly line showed that the coated tools reduced the extraction force to 20-75 % of those when using uncoated tools.  Both the number and the size of surface scratches in the grid plates were significantly reduced when using the DLC coated spacer tools.