Influences of the Glass Phase on Densification, Microstructure, and Properties of Low‐Temperature Co‐Fired Ceramics

Abstract

Multilayer ceramic devices based on low‐temperature co‐fired ceramics (LTCC) materials provide a very promising technology. Most LTCC tapes available today contain considerable fractions of glass powders to lower the sintering temperature. However, the glassy phases offer more possibilities to set a proper sintering behavior, on the one hand, and to tailor the desired properties of the final LTCC substrate, on the other. The exploitation of demixing and subsequent crystallizing glass compositions was shown on an example of a low‐permittivity (4.4)—low‐loss (1.5 × 10−3) LTCC with a high quartz content. In another LTCC material, undesired demixing could be restricted and the crystal phase anorthite could be triggered by partial dissolution of alumina in the liquid phase during sintering. To estimate the effect of silver diffusion in the latter material, the surroundings of a pure silver via were studied. A silver‐contaminated range of 50 μm was detected. Using model glasses containing silver oxide, a strong influence of dissolved silver on viscosity and crystallization behavior of the liquid phase was demonstrated. The dielectric properties of the sintered substrates were not degraded.

Effect of oxygen partial pressure on co-firing behavior and magnetic properties of LTCC modules with integrated NiCuZn ferrite layers

“…Interaction between silver metallization and LTCC-layers is well known [20][21][22][23][24][25][26][27]. This might be a source of defect formation in co-fired LTCC modules such as delamination, camber and local color changes.…”

“…Shrinkage mismatch inside LTCC-modules caused by silver migration has been recognized as a major source of defects and might generate warping and delamination. Sintering under reduced oxygen partial pressure, on the other hand, is known to minimize silver diffusion and leads to enhanced contour accuracy of components [26].…”

Sintering behavior and dielectric properties of SrB2Si2O8 ceramics

“…silver, copper, gold, with low conductor loss and low electrical resistance at high frequencies [1,2]. So far, glass-ceramics and ceramic/glass composites have been widely researched for LTCC application due to their tailored physical properties and low sintering temperature [3]. The preparation of glass-ceramics is achieved by a devitrification of glass materials.…”

Crystallization and dielectric properties of low temperature dielectrics containing Li2O filler

“…Alumina has been the common choice for the filler material due to its excellent electrical and mechanical properties and chemical inertness [5] and there have been limited studies for utilization of other materials as filler [6][7][8]. Physical and electrical properties of fired LTCC materials ultimately depend on both crystalline phase and residual glassy phase, and on the glass-to-dispersed crystal ratio [9].…”