New LTCC-hexaferrites by using reaction bonded glass ceramics

Karmazin, Roman; Dernovsek, O.; Ilkov, N.; Wersing, W.; Roosen, Andreas; Hagymási, Marcel

doi:10.1016/j.jeurceramsoc.2005.03.064

Cited by 21 publications

(13 citation statements)

References 5 publications

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“…The choice of filler depends on the dielectric demands of the microelectronic device. The most commonly used filler is alumina, 3 but mullite, 3 cordierite, 4 barium titanate, and ferrites 5 are also applied to achieve specific properties. Because none of these pure, undoped filler materials can be densified at temperatures around 900°C, the composites contain a low softening glass, which is responsible for sufficient densification.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, the glass phase is partially crystallized during firing to improve the properties and shape stability. In the last few years, attempts have been made to densify LTCC materials that possess a low glass content <10 vol% in order to take maximum advantage of the physical properties of the ceramic filler component and to reduce the losses in the GHz range 5,9,10 …”

Section: Introductionmentioning

confidence: 99%

“…In the last few years, attempts have been made to densify LTCC materials that possess a low glass content o10 vol% in order to take maximum advantage of the physical properties of the ceramic filler component and to reduce the losses in the GHz range. 5,9,10 Although various publications address the LTCC technology, only a few papers have discussed the sintering behavior and micro-structural development of LTCCs. Several investigations are restricted to the macroscopic shrinkage characterization, the phase development during densification, or rather during crystallization.…”

Section: Introductionmentioning

confidence: 99%

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Viscous Flow as the Driving Force for the Densification of Low‐Temperature Co‐Fired Ceramics

Kemethmüller

Hagymási

Stiegelschmitt

et al. 2006

Journal of the American Ceramic Society

104

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Filled glass–ceramic composites, like low‐temperature co‐fired ceramics (LTCC), must densify at temperatures <900°C. The densification mechanism of LTCC is often described by liquid‐phase sintering. The results of this paper clearly show that densification of ceramic‐filled glass–composites with a glass content above 60 wt% can be attributed to viscous sintering, which is decisively controlled by the viscosity of the glass during the heat treatment. This is demonstrated by the experimental determination of the viscosity of a MgO–Al2O3–B2O3–SiO2 glass dependent on temperature, by investigation of the wetting behavior of the glass on the ceramic filler mullite, and of the microstructural development. It was found that the glass does not wet the filler material in a temperature range up to 1000°C. Therefore, liquid‐phase sintering can be excluded. Independent of any wetting effect and therefore in the absence of capillary forces, densification starts at a temperature of 750°C, which corresponds to a viscosity of 109.5 dPa·s. This densification can be attributed to viscous flow of the glass matrix composite.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Viscous Flow as the Driving Force for the Densification of Low‐Temperature Co‐Fired Ceramics

Kemethmüller

Hagymási

Stiegelschmitt

et al. 2006

Journal of the American Ceramic Society

104

View full text Add to dashboard Cite

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“…Because of high sintering temperature above 1200°C, the conventional M-type hexaferrites cannot co-fire with the inner electrode metal Ag with melting point of 961°C in LTCC systems. Interestingly, the sintering temperature of these ferrites can be reduced to 900°C by using some glass phase or metallic oxide as sintering aids, but their magnetic properties decrease accordingly [6][7][8][9]. How to improve their low temperature sintering characteristics is significant for the miniaturization and integration of new microwave LTCC modules.…”

Section: Introductionmentioning

confidence: 99%

Effect of La–CO substitution on the crystal structure and magnetic properties of low temperature sintered Sr1−La Fe12−Co O19 (x=0–0.5) ferrites

Peng

Wang

et al. 2015

Journal of Magnetism and Magnetic Materials

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“…Sintering additives like various glasses are used to reduce the sintering temperature to below the melting point of Ag, a major constituent of common metallization pastes. Ba hexaferrites were recently adapted to LTCC for microwave applications [6,7] but NiCuZn ferrites have found even more interest due to their good processability and performance up to several 10 MHz. Relative permeabilities of up to 400 and inductances of several 100 μH were reported [8].…”

Section: Introductionmentioning

confidence: 99%

Low temperature cofirable MnZn ferrite for power electronic applications

et al. 2007

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A new MnZn ferrite tape material for sintering at 900°C and its performance in power electronic embedded multilayer inductors of several μH inductance are described. The low sintering temperature is achieved by optimizing powder processing and sintering additives. The material is suited for processing within the low temperature cofired ceramics (LTCC) technology and it is particularly compatible with low loss Ag metallization. Although reduced by a factor of two compared to high-temperature sintered material, its relative amplitude permeability of 700 allows for numerous device applications below the Curie temperature of 260°C. Volumetric losses are not affected by the new material formulation since increased hysteresis losses are compensated by reduced eddy current losses. Power line filters with ceramic integrated inductors and surface mounted capacitors exhibit a current capacity of up to 10 A and a shift in cutoff frequency compatible with the measured B-H curve of the material. By integration of these inductors with conventional dielectric LTCC tapes a strain-induced permeability quenching is revealed and attributed to magnetostriction. Therefore good thermal matching between tape materials is needed, but the effect also permits construction of variometers and pressure sensors without moving mechanical parts.

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New LTCC-hexaferrites by using reaction bonded glass ceramics

Cited by 21 publications

References 5 publications

Viscous Flow as the Driving Force for the Densification of Low‐Temperature Co‐Fired Ceramics

Viscous Flow as the Driving Force for the Densification of Low‐Temperature Co‐Fired Ceramics

Effect of La–CO substitution on the crystal structure and magnetic properties of low temperature sintered Sr1−La Fe12−Co O19 (x=0–0.5) ferrites

Low temperature cofirable MnZn ferrite for power electronic applications

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