Browsing by Author "Jao, Jui-Chu"

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Characterization of inductor with Ni-Zn-Cu ferrite embedded in B2O3-SiO2 glass
(2007-09-01)
Jao, Jui-Chu
;
Li, Pang
;
Wang, Sea-Fue
;
材料科學與工程學系
;
Department of Materials Science and Engineering
In this study, inductors using a new low-temperature cofirable ceramic (LTCC) design, in which Ni-Zn-Cu ferrite was buried in B2O3-SiO2 glass within the core of the spiral silver coil, were fabricated. The inductance and quality factor of the inductor with embedded ferrite are larger than those of pure B2O3-SiO2 glass. Ni-Zn-Cu ferrite was incompatible with the B2O3-SiO2 glass during the cofiring process due to sintering shrinkage mismatch. The incompatibility was resolved when 35 wt % Al2O3 was doped into the B2O3-SiO2 glass, which produces a glass-ceramic, and 2 wt % of Bi2O3 was fluxed into the Ni-Zn-Cu ferrite as a sintering aid. The addition of 2 wt % of Bi2O3 not only enhances densification, but also increases the permeability of Ni-Zn-Cu ferrite.
Method of estimating dielectric properties of dielectric layers in low-temperature-cofired ceramic devices
(2006-11-01)
Jao, Jui-Chu
;
Lin, Pang
;
材料科學與工程學系
;
Department of Materials Science and Engineering
method of estimating the dielectric constant (E) of dielectric layers in low-temperature-cofired ceramic (LTCC) devices was developed. A band-pass filter (BPF) circuit was designed such that its second harmonic frequency (SHF) strongly depended on the epsilon of the relevant capacitor built in the BPF. The epsilon-SHF correlation was established by model simulation. The design of the BPF was realized with various dielectric layers, and the measured SHF was used to determine the E values of the capacitors from the epsilon-SHF relationship. These epsilon values were found to be consistent with those of the sintered pellets, prepared with the same dielectrics and process as BPFs. The e values of the dielectric layers in other LTCC devices were estimated by this method, in which the BPFs made of the same dielectric layers were fired as dummy samples along with the devices.
Self-constraining method for low shrinkage of low-temperature-cofired ceramic devices
(2007-06-01)
Jao, Jui-Chu
;
Lin, Pang
;
材料科學與工程學系
;
Department of Materials Science and Engineering
A new technique developed for the low shrinkage of low-temperature-cofired-ceramics (LTCCs) is proposed; this technique is based on a self-constraining mechanism, which relies on composite green tapes formed by two laminated glass layers, each of which has a distinct softening point (onset shrinkage temperature, OST) and a crystallization temperature (CRT). Each layer works as a constraining layer for the other layer in a distinct temperature range to prevent excessive linear shrinkage along the layer plane. The OSTs ranging from 802 to 606 degrees C are adjusted by controlling the amount of Na2O (0-1.0 wt %) added to the CaO-SiO2 glass. The OST and CRT of the two glass layers as well as the heating profile have strong effects on shrinkage ratio, the lowest of which is found to be only 0.2% after sintering up to 880 degrees C. The measured dielectric constant of the sintered samples is approximately 6.0 within a narrow variation range even when the samples have a wide range of shrinkage ratios.