RADIO FREQUENCY THERMAL PLASMA TREATMENT FOR SIZE REDUCTION AND SPHEROIDISATION OF GLASS POWDERS USED IN CERAMIC ELECTRONIC DEVICES

• Published in: Journal of the American Ceramic Society 2007-01, Vol.90 (6), p.1717-1722
• Main Authors: Seo, J H, Kim, D U, Nam, J S, Hong, S H, Sohn, S B, Song, S M
• Format: Article
• Language: English
• ISSN: 0002-7820

Radio frequency (RF) thermal plasma treatment for the size reduction and the spheroidisation of coarse glass particles to change them into submicron-sized powders of spherical shape was studied. Such ultra-fine spherical powders are important as a sintering aid to achieve efficient package and high performance in ceramic electronic applications. The coarse glass powders injected into the high-temperature RF thermal plasma underwent rapid heating, melting, and evaporation, followed by quenching, and then condensed to very fine spherical powders. In the thermal plasma treatment with high RF powers of 18-23 kW at a powder feeding rate of 3 g/min, SEM images and particle size distribution graphs obtained from the treated glass powders indicated that most glass powders with initial average diameters of around 2 micron were reformed into spherical ones with sizes < 500 nm. In a 4 MHz RF thermal plasma reactor the maximum size of particles decreased down to 200 nm when the reactor was operated under conditions of reduced pressure, low powder feeding rate, and high RF power. The compositions of glass powders before and after the plasma treatment were compared using wet and ICP-optical emission spectroscopy analyses. Negligible composition changes appeared within a range of < 2 wt% during the RF thermal plasma process, which showed the successful preparation of submicron-sized glass powders of a spherical shape applicable to the advanced ceramic electronic devices. 18 refs.