“…[6][7][8][9][10][11][12][13][14] However, the use of sintering additives (e.g., Li 2 CO 3 , H 3 BO 3 , and BaCu(B 2 O 5 ), and low-melting glass) will, without exception, decrease the Q × f value. 6,7,9,14 Moreover, the additions of τ f compensator materials (e.g., TiO 2 and CaTiO 3 ) usually lead to an increase in the sintering temperature. 8,[10][11][12][13] Therefore, in recent years, additivefree LTCC systems have aroused much attention from researchers who study electronic ceramic materials.…”