Silver diffusion and microstructure in LTCC multilayer couplers for high frequency applications

Low temperature cofired glass ceramic-Ag metal electrode (LTCC) systems wer e investigated in relation to Ag diffusion and microstructural development in the fabrication of high frequency couplers. Sintering temperature was in a range of 825 degrees C-975 degrees C. Ag diffusion was not observed belo w 875 degrees C but densification of the electrode was greatly improved. At higher temperature above 900 degrees C, Ag ions were diffused through glas s phases containing Pb and alkali ions. Crystalline phases behaved as a bar rier for the Ag diffusion. With increasing sintering temperature, glass inf iltration to the electrode also occurred due to increased fluidity of the g lass phase and the electrode line were severely deformed and damaged. (C) 2 000 Kluwer Academic Publishers.