Al2O3-MgO-ReOx (Re: Rare Earth)-Based LTCC and its Application to Multilayer Non-Shrinkage Substrate for Microwave Devices

Abstract

We studied the dielectric properties of Al 2 O 3 -MgO-ReO x (Re: rare earth) systems in the microwave region and found that the magnetoplumbite phases in the MgO-poor regions of MgReAl 11 O 19 (Re: La ∼ Tb) compositions had positive TCF (temperature coefficient of resonance frequency) values in spite of having low dielectric constants of under 20. By mixing a lead-free glass with the above system, a novel LTCC (which we term an AMSG) was obtained that was characterized by a low dielectric constant (<10), a near zero TCF, and high bending strength. When firing these AMSG green sheets inserted between HTCC alumina or magnesia green sheets that cannot be sintered at the AMSG sintering temperature, the AMSG sheets were seen to shrink not in the x-y directions but in the z direction due to the constraining effects of the HTCC layers. The obtained non-shrinkage substrate had precise dimensions and a high degree of flatness. The AMSG and the non-shrinking techniques have potential for application to integrated RF modules in mobile communications equipment.

Effects of various oxide fillers on physical and dielectric properties of calcium aluminoborosilicate-based dielectrics

“…The low temperature co-fired ceramic (LTCC) technology has been extensively studied from its technical and commercial significance in the field of highly-integrated electronic components and modules [1][2][3][4]. The LTCC system generally consists of glass and ceramic.…”

Low-temperature cofiring behavior of ZnTiO3 dielectrics/NiZnCu ferrite composites

“…The samples were sintered at 900 • C in air for 4 h using free sintering (conventional sintering method) and restricted shrinkage sintering, respectively. Restricted shrinkage sintering is sintering the multilayer ceramic green body with no-shrinkage alumina substrate on both sides [10,11]. During firing, the multilayer ceramic in middle layer can be bonded by the sintered rigid board.…”

“…Therefore, the ceramic green sheets shrink in the z direction, not in the x-y directions, due to the 0925-8388/$ -see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.jallcom.2008.02.049 constraining effects of the no-shrinkage alumina substrate layer [10,11]. The result of using restricted shrinkage sintering is obtaining the no camber and cracks multilayer composite samples, as are shown in Fig.…”

Low Temperature Cofired Ceramics

“…The best dielectric properties, Qf = 72 000 GHz and " r = 8 at 13 GHz, with low firing temperatures of 900°C were found when the mixing ratio of La 2 O 3 -2B 2 O 3 -0.5ZnO was 20% crystalline melt and 80% amorphous melt. Kagata et al [92] reported MgO-Sm 2 O 3 -Al 2 O 3 (MgSmAl 11 O 19 ) and Al 2 O 3 -SiO 2 -B 2 O 3 in equal amount, and sintering at 920°C resulted in LTCC with " r = 7.8, Qf = 10 000 GHz and f = þ6 ppm/°C. Chang and Jean [93] studied the crystallization kinetics and mechanism of low " r , low temperature, cofireable CaO-B 2 O 3 -SiO 2 glass ceramics using commercially available A-6 tapes.…”