Application of diamond-like carbon films to spacer tools for electron gunsof cathode ray tube (CRT)

The surface properties of spacer tools, which are sliding between grid plat es of electron gun for cathode ray tube (CRT) to control the space gap betw een 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 t he 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 coming o ut from the cathode of CRT, it was very important to keep the surface of to ols smooth and clean. Furthermore, the productivity of the electron gun ass embly process is significantly dependent on the friction between the tool a nd the plate surface. Diamond-like carbon (DLC) film of 800-nm thickness wa s deposited on both surfaces of the spacer tools to improve the tribologica l properties and wear resistance. The film was deposited by a plasma enhanc ed CVD method using a 13.56 MHz radio frequency with benzene. Si intermedia te layers were used to improve the adhesion of DLC film. Process parameters for Ar cleaning and Si intermediate layers were optimized in the viewpoint of adhesion improvement of DLC films to tool steel substrates. The held te st in the electron gun assembly line showed that the coated tools reduced t he 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 significan tly reduced when using the DLC coated spacer tools. (C) 2000 Elsevier Scien ce B.V. All rights reserved.