Abstract: During T/R module assembly，the large area soldering coverage of low temperature cofired ceramics(LTCC) is usually low．Because of pollution and oxidization layer on soldering surface and soldering terminal，the wettability of soldering surface and soldering terminal is poor．Since there are no proper protective atmosphere and deoxidization atmosphere during large area soldering，the soldering surface and soldering terminal are reoxidized very easily．Besides，the improper use of the flux will produce some flux residues．All of these are important reasons why the large area soldering coverage is low． Some effective ways to improve the wettability of soldering surface and soldering terminal are introduced in this paper，such as plasma chemical cleaning and hydrogen plasma reflow soldering．These modern technologies can realize the large area soldering without flux and will play an important role in improving large area soldering coverage of LTCC．