• 한국전기전자재료학회논문지
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• 제17권9호
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• pp.942-946
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• 2004

The crystalline and dielectric properties on Al$_2$O$_3$ filled glass frit (CaO-Al$_2$O$_3$-SiO$_2$-MgO-B$_2$O$_3$) with admixtures of TiO$_2$ have been investigated. The dielectric constant value of 7.5 ∼ 7.8, qualify factor value of 700 were obtained for glass frit : Al$_2$O$_3$(50 : 50 wt%) ceramics. Addition of TiO$_2$ less than 5 wt% slightly increased the dielectric constant from 7.8 to 8.8 due to higher dielectric constant of TiO$_2$. With increasing the amount of TiO$_2$ up to 5 wt%, the temperature coefficient of dielectric properties was improved. When the TiO$_2$ 5 wt% were added, dielectric properties were dielectric constant 8.8, quality factor 840 and the temperature coefficient of dielectric 45 ppm/$^{\circ}C$ at a sintering temperature 920$^{\circ}C$.

• Journal of electromagnetic engineering and science
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• 제10권3호
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• pp.92-98
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• 2010

A new wideband bandstop filter(BSF) with a sharp roll-off characteristic is introduced in a stripline structure in this paper. The BSF consists of two sections: the first is two capacitively coupled $\lambda/4$ short-circuited lines with opposite ground positions, while the second is a capacitively coupled $\lambda/4$ short-circuited line. The BSF provides three transmission zeros within the stopband and better than 22 dB rejection over the whole wireless local area network (WLAN) band from 5.15 to 5.825 GHz. The BSF, cascaded to an U.S. ultra-wideband(UWB: 3.1~10.6 GHz) band-pass filter(BPF), is simulated with HFSS and realized with low-temperature co-fired ceramic(LTCC) green tape with a dielectric constant of 7.8. The measurement results agree well with the HFSS simulation results. The size of the UWB BPF including the BSF is $3{\times}6.3\times0.45\;mm^3$.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2007년도 춘계학술대회 논문집
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• pp.71-74
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• 2007

Substitution of the stacked antenna for the normally pressed antenna in the mobile phone was tried for the purpose of decreasing its size. However, reduced size resulted in the difficulties obtaining the targeted characteristics with the bandwidth over 70MHz. The cross-section of the vias in the low temperature co-firing ceramics process was studied to find out effects on the bandwidth characteristics. Circular and rectangular cross-section of the via beneath different types of antenna patterns were simulated. Better bandwidth characteristics were acquired for the larger diameter of the circular section and for the rectangular section as the cross-section area increased. From the viewpoint of the shape of the cross-section, rectangular area showed better characteristics than the circular area with the same longest length in the cross-section.

• 한국세라믹학회지
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• 제56권6호
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• pp.526-533
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• 2019

Indialite/cordierite glass-ceramics demonstrate excellent microwave dielectric properties such as a low dielectric constant of 4.7 and an extremely high quality factor Qf of more than 200 × 10³ GHz when crystallized at 1300℃/20 h, which are essential criteria for application to 5G/6G mobile communication systems. The glass-ceramics applied to dielectric resonators, low-temperature co-fired ceramic (LTCC) substrates, and direct casting glass substrates are reviewed in this paper. The glass-ceramics are fabricated by the crystallization of glass with cordierite composition melted at 1550℃. The dielectric resonators are composed of crystallized glass pellets made from glass rods cast in a graphite mold. The LTCC substrates are made from indialite glass-ceramic powder crystallized at a low temperature of 1000℃/1 h, and the direct casting glass-ceramic substrates are composed of crystallized glass plates cast on a graphite plate. All these materials exhibit excellent microwave dielectric properties.

• 한국재료학회지
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• 제14권10호
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• pp.731-736
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• 2004

Herein, we report on the co-firing of a low-K wiring substrate and a middle-K functional substrate in LTCC. Firstly, we researched the sintering behavior and dielectric properties of the low-k wiring substrate comprised by alumina and glass frit with ${\varepsilon}_r$, of $\sim7$ and the middle-k functional substrate comprised by $Ba_{5}Nb_{4}O_{15}$ and glass frit with ${\varepsilon}_r$, of $20\sim30$. The warpage and delamination between the hetero layers of the low-K and the middle-K composition were also studied. In particular, physical matching of the hetero layers could be possible by adjusting of the sintering properties of the composition. We observed that an introduction of the glass frit to the low- and middle-K substrate gives rise to a minimization of an effect given by separation of the hetero layers, and modification of the fraction of the glass frit accompanied by a variation of the composition could control the sintering behavior and its beginning temperature. In the case of co-firing of the L03 as the low-K wiring substrate composition and the M03 as the middle-K functional substrate composition at $875^{\circ}C$, we could fabricate a desirable structure of hetero layers without any kinds of structural defects such as separation, warpage, delamination, pore trap, etc. We suppose that the co-firing techniques described in this study would provide a helpful method to fabricate a LTCC multi-functional for the next generation.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2002년도 추계기술심포지움논문집
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• pp.169-172
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• 2002

Silver pastes for inner conductor in the Low Temperature Co-fired Ceramics (LTCC) are composed of silver powder, binder, solvent and additives. The composition of the chemicals have influence on rheology, printability, shrinkage rate, etc. In this study, commercial Ag pastes and Ag pastes made in KETI were investigated to find the relationship between characteristics of Ag paste and solid contents. Ag pastes with 68~90 wt% Solid Contents were tested. Substrate/paste matching property and conductivity of the conductor lines showed large dependence on solid contents of Ag paste.

• 마이크로전자및패키징학회지
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• 제11권3호
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• pp.17-22
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• 2004

[ $CaZrO_3$ ]세라믹스에 대하여 $CaTiO_3$세라믹스의 첨가량 변동에 따른 마이크로파 유전특성을 조사하였다. 또한 중유전율 LTCC 기능성 기판으로 활용하기 위하여 저융점의 유리 프리트를 첨가하여 $CaZrO_3-CaTiO_3$ 세라믹스의 저온 소결 거동과 마이크로파 유전특성을 평가하였다. 저온 소결 조제로 사용된 저응점의 유리 프리트를 $10-20 wt\%$ 범위로 첨가함으로서 $CaZrO_3-CaTiO_3$ 세라믹스의 소결온도를 $1450^{\circ}C$에서 $900^{\circ}C$이하로 낮출 수 있었다. 음의 온도계수를 갖는 $CaZrO_3$ 및 유리프리트에 대하여 양의 온도계수를 갖는 $CaTiO_3$ 세라믹스의 분율을 적정히 제어함으로서 제로의 온도계수를 구현할 수 있었다. $CaZrO_3-CaTiO_3$ 세라믹스에 저온 소결용 유리 프리트를 $15 wt\%$ 첨가하여 $875^{\circ}C$에서 소결한 경우. 유전율(k) 23, 품질계수(Q${\times}$f) 2500, 공진 주파수 온도계수$(T_f) -3 ppm/^{\circ}C$의 매우 양호한 마이크로파 유전특성을 나타내었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 하계학술대회 논문집 Vol.8
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• pp.309-309
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• 2007

The LTCCs (low-temperature co-fired ceramics) are very important for electronic industry to build smaller RF modules and to fulfill the necessity for miniaturization of devices in wireless communication industry. The dielectric materials with sintering temperature $T_{sint}$<$900^{\circ}C$ are required. In this study, we investigated with glass-ceramic composition, which was crystallized with two crystals. The microstructure, crystal phases, thermal and mechanical properties, and dielectric properties of the composites were investigated using FE-SEM, XRD, TG-DTA, 4-point bending strength test and LCR measurement. The starting temperature for densification of a sintered body was at $779{\sim}844^{\circ}C$ and the glass frits were formatted to the crystal phases, $CaAl_2Si_2O_8$(anorthite) and $CaMgSi_O_6$(diopside), at sintering temperature. The sintered bodies exhibited applicable dielectric properties, namely 6-9 for ${\varepsilon}_r$. The results suggest that the glass-ceramic composite would be potentially possible to application of low dielectric L TCC materials.

• 한국전자파학회지:전자파기술
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• 제12권3호
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• pp.12-24
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• 2001

최근에 이동통신 시스템의 다기능/고기능화에 따 라 여러 선진업체에서 RF부품의 모듈화 개발이 추 진되고 있으며, 이에 대응하여 LTCC를 이용한 MCM (Multi-Chip Module)적층기술의 개발이 확대되고 있 다. 이 기술은 세라믹기판 내부에 L, C, R등의 수 동소자를 3차원적으로 구성, 일체화할 수 있기 때문 에 이들 수동소자 뿐 아니라 세라믹 개별 부품으로 이용되고 있는 대역통과 여파기 및 바이어스라인, 임피던스 매칭 회로, 스트립라인등을 하나의 구조물 에 집적화 시킴으로써 제품의 소형화 및 대량생산 이 가능해진다. 본 논문에서는 LTCC를 활용한 고 집적 복합모듈 기술과 동향에 대한 개요 및 개발사례로서 적층 VCO 모듈의 제작에 대해 소개하기로 한다.

• 한국세라믹학회지
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• 제41권8호
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• pp.599-604
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• 2004

무선 이동통신 산업에서 소형화와 RF모듈을 구현하기 위해 저온 동시 소성 세라믹(LTCC)기술이 부각되고 있다. LTCC용 재료는 90$0^{\circ}C$ 이하의 온도에서 소성이 되어야 한다 본 연구는 BaO-N $d_2$ $O_3$-Ti $O_2$ (BNT：20∼40wt%) 세라믹과 L $a_2$ $O_3$- $B_2$ $O_3$-Ti $O_2$ (LBT：80∼60wt%) 유리를 혼합하여 유리를 결정화시킴으로, 나타나는 부수적인 효과를 얻고자 하였다. 이에 소결 거동, 결정상 분석, 상대밀도 그리고 유전특성을 평가하였다 80wt% 유리의 첨가는 90%에 가까운 상대밀도를 갖는 복합체로서 15에 가까운 유전율과 10000GHz의 품질계수와 같은 우수한 유전특성을 보였다. 이와 같은 결과는 유리 결정화를 이용하여 LTCC용 유전체에 적용될 수 있는 가능성을 부여하였다.