Search

In this study, a low-temperature co-fired ceramic (LTCC)-based direct current (DC)-DC converter is proposed for reducing stray inductance and mitigating electromagnetic interference. The dominant radiating loop of the proposed LTCC-based DC-DC converter features a multilayer design, which helps suppress noise sources and reduce radiated emissions. The peak voltage of switching noise for the proposed DC-DC converter at the frequency of 500 kHz is approximately 8.98% lower than that of a conventional DC-DC converter. In addition, the radiated emission level of the proposed DC-DC converter is lower than that of the conventional DC-DC converter. In sum, the proposed LTCC-technology-based multilayer design reduces the peak voltage of switching noise and the radiated emission of the DC-DC converter.

In this paper, the influence of the CaO content in glass on the sintering behaviour, structure, and properties of CaO-B₂O₃-Al₂O₃-SiO₂ glass/Al₂O₃ composites for low-temperature co-fired ceramic materials was studied. The results show that an increase in the CaO content in the glass reduces the polymerisation degree of the glass network, thereby reducing the glass viscosity and promoting the densification of the liquid phase sintering, increasing the crystallisation tendency of the material, reducing the crystallisation peak temperature and promoting the precipitation of anorthite in the material. The sintering activation energy of the glass/Al₂O₃ first decreases and then increases, and reached a minimum in C4. The anorthite can reduce the bulk density and coefficient of the thermal expansion of the materials, and an appropriate amount of anorthite can improve the flexural strength of the material by more than 190 MPa. When the CaO content in the glass increases, the required sintering temperature for the material to achieve the maximum flexural strength is lower. The sample (C4-850) with a CaO content of 27.60 %, achieving densification when sintered at 850 °C for 1 h, showed a flexural strength of 190.1 MPa and a coefficient of thermal expansion of 6.083× 10-6 K-1, which is suitable for substrate packaging.

In this work, we successfully integrated the high-entropy concept into LiMgPO 4 -based ceramics by strategically substituting Mg2+ with various divalent ions. Through a low-temperature solid-phase reaction method, a series of high-entropy LiMg 0.9 R 0.1 PO 4 (R = Ni, NiCo, NiCoZn, NiCoZnCu, NiCoZnCuMn) ceramics were prepared successfully, and their MW dielectric properties were found to be heavily influenced by the ionic character, lattice energy, bond energy, entropy, ion radius disorder, and electronegativity of chemical bonds. Remarkably, LiMg 0.9 (Ni 0.2 Co 0.2 Zn 0.2 Cu 0.2 Mn 0.2) 0.1 PO 4 (LM5RP) ceramics exhibited exceptional MW dielectric properties (ε r = 7.43, τ f = − 27.6 ppm/°C, and Q × f = 83,216 GHz@13 GHz and 105,889 GHz@28 GHz) when sintered at an extraordinarily low temperature of 900 °C for 2 h. To demonstrate the real-world applicability of the LM5RP high-entropy ceramic, we designed and fabricated a state-of-the-art millimeter-wave (mmWave) filter, operating at 28 GHz, using low-temperature co-fired ceramic (LTCC) packaging technology. The filter exhibited unparalleled performance, featuring a low insertion loss (0.9 dB) and wide stopband suppression (> 17 dB @ 2.14 f 0). These groundbreaking findings underscore the immense potential of high-entropy ceramics in revolutionizing advanced MW applications, particularly in the domain of B5G/6 G mmWave communication systems. [ABSTRACT FROM AUTHOR]

We propose a substrate with high thermal conductivity, manufactured by the low‐temperature co‐fired ceramic (LTCC) multilayer circuit process technology, as a new DC/DC converter platform for power electronics applications. We compare the reliability and power conversion efficiency of a converter using the LTCC substrate with the one using a conventional printed circuit board (PCB) substrate, to demonstrate the superior characteristics of the LTCC substrates. The power conversion efficiencies of the LTCC‐ and PCB‐based synchronous buck converters are 95.5% and 94.5%, respectively, while those of nonsynchronous buck converters are 92.5% and 91.3%, respectively, at an output power of 100 W. To verify the reliability of the LTCC‐based converter, two types of tests were conducted. Storage temperature tests were conducted at −20 °C and 85 °C for 100 h each. The variation in efficiency after the tests was less than 0.3%. A working temperature test was conducted for 60 min, and the temperature of the converter was saturated at 58.2 °C without a decrease in efficiency. These results demonstrate the applicability of LTCC as a substrate for power conversion systems.

Amaterial for low-temperature co-fired ceramic technology was developed in the Li2O–ZnO–TiO2 system for use in the manufacture of electronic components. The sintering temperature of the material was lowered from 1075 to 950°C by introducing 3% of a sintering additive with a eutectic composition in the Li2O–B2O3–SiO2 system. The developed ceramic obtained at 950°C is characterized by density 4.14 g/cm3 together with the following dielectric properties: permittivity ε = 23.1 and dielectric Q factor Q f = 832 MHz. [ABSTRACT FROM AUTHOR]

We propose a multilayered‐substrate‐based power semiconductor discrete device package for a low switching loss and high heat dissipation. To verify the proposed package, cost‐effective, low‐temperature co‐fired ceramic, multilayered substrates are used. A bare die is attached to an embedded cavity of the multilayered substrate. Because the height of the pad on the top plane of the die and the signal line on the substrate are the same, the length of the bond wires can be shortened. A large number of thermal vias with a high thermal conductivity are embedded in the multilayered substrate to increase the heat dissipation rate of the package. The packaged silicon carbide Schottky barrier diode satisfies the reliability testing of a high‐temperature storage life and temperature humidity bias. At 175 °C, the forward current is 7 A at a forward voltage of 1.13 V, and the reverse leakage current is below 100 μA up to a reverse voltage of 980 V. The measured maximum reverse current (IRM), reverse recovery time (Trr), and reverse recovery charge (Qrr) are 2.4 A, 16.6 ns, and 19.92 nC, respectively, at a reverse voltage of 300 V and di/dt equal to 300 A/μs.

We propose a substrate with high thermal conductivity, manufactured by the low‐temperature co‐fired ceramic (LTCC) multilayer circuit process technology, as a new DC/DC converter platform for power electronics applications. We compare the reliability and power conversion efficiency of a converter using the LTCC substrate with the one using a conventional printed circuit board (PCB) substrate, to demonstrate the superior characteristics of the LTCC substrates. The power conversion efficiencies of the LTCC‐ and PCB‐based synchronous buck converters are 95.5% and 94.5%, respectively, while those of nonsynchronous buck converters are 92.5% and 91.3%, respectively, at an output power of 100 W. To verify the reliability of the LTCC‐based converter, two types of tests were conducted. Storage temperature tests were conducted at −20 °C and 85 °C for 100 h each. The variation in efficiency after the tests was less than 0.3%. A working temperature test was conducted for 60 min, and the temperature of the converter was saturated at 58.2 °C without a decrease in efficiency. These results demonstrate the applicability of LTCC as a substrate for power conversion systems. [ABSTRACT FROM AUTHOR]

Abstract: Single phase of dense ixiolite structure Zn0.5Ti0.5NbO4 (ZTN) microwave dielectric ceramics were synthesized at low temperature (850°C‐900°C) via solid state reaction with small amount of Li2O‐B2O3‐SiO2 (LBS) glass. There is a liquid phase generated by LBS at about 760°C, which significantly enhances the shrinkage and decreases the activation energy. And with the assistance of liquid phase, single phase of ZTN with orthorhombic structure is detected, sintering temperature of ceramics drops from 1125°C to 850°C and still maintain high relative density (>97%) with great microwave dielectric properties (εr ~ 34.32, Q×f ~ 17740 GHz). Ceramics with 0.5 wt. % LBS cannot be sintered and densified, and the lack of densification determines a lower dielectric constant, large dielectric loss, and undetectability of temperature coefficient of resonant frequency. With the increase in LBS, a dense structure can be formed, but the deterioration of performance should be mainly attributed to the variation in LBS glass content. [ABSTRACT FROM AUTHOR]

The aim of this work is the integration of an improved graphite–epoxy composite electrode modified with the acetylcholinesterase enzyme as a detector into a green tape ceramic microfluidic device for the online amperometric determination of pesticides. First, the operational conditions of the microfluidic system were optimized for the enzymatic substrate determination of acetylthiocholine. Good results were achieved for acetylthiocholine determination, obtaining a low detection limit and optimal sensitivity. The analytical performance of the microanalyzer was evaluated with organophosphorus and carbamate pesticides across a wide concentration range. Pesticides were determined indirectly measuring the enzymatic inhibition effect that they caused. The analysis was based on stopped-flow methodology with a three-step strategy: enzymatic substrate measurement, enzymatic inhibition by pesticide contact with the biosensor, and enzymatic substrate measurement after the inhibition process. The pesticide concentrations were determined by the percentage of inhibition produced. The microanalyzer was used for the analysis of spiked irrigation water samples using this indirect method. The low-temperature co-fired ceramic/epoxy–graphite–acetylcholinesterase microfluidic system showed low limits of detection and adequate sensitivity. The recoveries of the spiked water samples were approximately 100% with relative standard deviation values lower than 5% for three replicate measurements. All results obtained are indicative of a convenient, rapid, sensitive, and economic method for the determination of pesticides in environmental samples. [ABSTRACT FROM AUTHOR]

We propose a multilayered-substrate-based power semiconductor discrete device package for a low switching loss and high heat dissipation. To verify the proposed package, cost-effective, low-temperature co-fired ceramic, multilayered substrates are used. A bare die is attached to an embedded cavity of the multilayered substrate. Because the height of the pad on the top plane of the die and the signal line on the substrate are the same, the length of the bond wires can be shortened. A large number of thermal vias with a high thermal conductivity are embedded in the multilayered substrate to increase the heat dissipation rate of the package. The packaged silicon carbide Schottky barrier diode satisfies the reliability testing of a high-temperature storage life and temperature humidity bias. At 175 °C, the forward current is 7 A at a forward voltage of 1.13 V, and the reverse leakage current is below 100 μA up to a reverse voltage of 980 V. The measured maximum reverse current ( IRM), reverse recovery time ( Trr), and reverse recovery charge ( Qrr) are 2.4 A, 16.6 ns, and 19.92 nC, respectively, at a reverse voltage of 300 V and d i/d t equal to 300 A/μs. [ABSTRACT FROM AUTHOR]

In this paper we consider software implementation of three-dimensional modeling of thermal processes in multilayer integrated circuits based on low-temperature co-veneering ceramic. The results obtained by the software implemented by the example of the radio frequency receiver module based on low-temperature ceramics for autonomous navigation systems. And also provides a comparison with the results of certified software product.

A low‐temperature co‐fired ceramic (LTCC) filtering power divider with harmonic suppression is presented. It is composed of three resonators and one resistor. By using 3D technology, the two output resonators are symmetrically coupled to the input resonator to obtain the power splitting response. Each splitting path is composed of two resonators to achieve the filtering response. The resistor for isolation is located on the top layer and connected to the two output ports by vertical strips on the side walls. The broadside couplings between resonators produce required passband and stopband. A compact filtering power divider with the core size of 0.122λg × 0.1λg × 0.059λg is implemented. Good filtering, power splitting and isolation performance are achieved. What is more, the second harmonic is successfully rejected below 20 dB without any extra circuit. [ABSTRACT FROM AUTHOR]

This paper presents the design of a 1: 50 bondwire micro-transformer assembled with IC gold bonding wires and a toroidal LTCC magnetic core with race-track shape. The transformer is fabricated on-top of a standard BCD IC in a 15 mm 2 footprint area for micro-power energy harvesting applications. Measurements show a secondary self-inductance up to 29 μH with a maximum Q -factor of 11.6 at 1.3 MHz, and a coupling coefficient of 0.65 with an effective turns ratio of 19. This miniaturized technology finds also applications in power supply in package (PwrSiP) and power supply on chip (PwrSoC). [ABSTRACT FROM AUTHOR]

ABSTRACT A miniaturized and wideband lumped-element branch-line coupler is proposed in a 10-layer low-temperature co-fired ceramic (LTCC) substrate for dozens of megahertz applications. The proposed topology not only enables a wide fractional bandwidth of 32.3% with a small number of elements but also makes the required capacitance and inductance lower for element size reduction. The further miniature is achieved using vertically interdigital-capacitors with eight fingers and spiral inductors with 9.5 turns. The proposed coupler has the smallest reported size of only 0.005 × 0.004 × 0.0004 λg. Measured S11, S21, S31, and S41 are better than −15, −4.6, −3.9, and −13 dB from 52 to 72 MHz, respectively. And inband phase difference between the coupled and direct ports is within 91° ± 1°. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2001-2005, 2014 [ABSTRACT FROM AUTHOR]

A novel low-temperature co-fired ceramic dual-band bandpass filter with a compact size and high selectivity is reported using vertically coupled lines and semi-lumped resonators. Due to the source–load coupling and the characteristics of the resonators, five transmission zeros are introduced to improve the selectivity of the filter. A dual-band filter located at 2.45 and 5.2 GHz has been designed and fabricated in a low-temperature co-fired ceramic substrate to verify the proposed design concept. With the assistance of the vertical coupling structure and low-temperature co-fired ceramic technology, the filter occupies an area of 7.3 × 6.2 mm2. [ABSTRACT FROM AUTHOR]

An aperture-coupled multi-layer parasitic patch array antenna operating at the Ka-band has been developed based on low-temperature co-fired ceramic technology. E-shaped parasitic patches are employed to direct the antenna radiation toward the broadside direction, thus improving the gain. Meanwhile, the parallel slots in the parasitic patches excite multiple resonant modes to broaden the bandwidth. The antenna shows a measured 10-dB impedance bandwidth of 28% (31.1 to 41.2 GHz) with a gain of >6 dBi at 31 to 38 GHz. A mutual coupling of <−18 dB is measured between adjacent elements with a center-to-center spacing of 6 mm (0.7λ0at 35 GHz). A two-element array was also developed, which exhibits a measured 10-dB impedance bandwidth of 26% (31.5 to 40.7 GHz), as well as a gain >8.8 dBi at 31 to 37 GHz and a peak gain of 9.7 at 36 GHz. The proposed antenna achieves wide bandwidth and relatively high gain, which is suitable for millimeter-wave radars and high data-rate communication systems. [ABSTRACT FROM AUTHOR]

Metamaterials are artificially engineered metallo-dielectric microstructures that display strong resonance behavior although their electrical size is \sim0.1∼\lambda. Individually they behave like LC oscillators and collectively they give rise to effective permittivity and permeability that are highly dispersive in the resonance region and may even become negative. In this paper, metamaterials with 3-D interconnects are designed for low-temperature co-fired ceramic (LTCC) fabrication. The fabricated materials are characterized experimentally using a free-space measurement system in the 33–110 GHz range. Dupont 951 is chosen as the substrate with silver ink for metallization. Three-layer and five-layer samples were fabricated. The fabricated samples exhibit electric resonance, magnetic resonance, or both, depending on the orientation and geometry of the metallic microstructure. The materials are passive and may be modeled using series and/or parallel LC circuits. LTCC metamaterials are proposed for packaging applications in microwave integrated circuits that may require embedded passive inductors, capacitors, resistor elements, and circuits that are functional at required frequencies and are inactive at other frequencies. [ABSTRACT FROM AUTHOR]

A very compact wireless local area network antenna using meander striplines in three low-temperature co-fired ceramic layers is designed and fabricated in this study. This chip antenna has a small volume of only 3.2 × 1.6 × 2 mm3. The measured radiation bandwidths (voltage standing wave ratio ≤ 2) of 2.45 and 5.8 GHz are 110 and 150 MHz, and the peak gains of the two bands are −1.6 and 2.7 dBi, respectively. The resonant frequencies can easily be tuned by adjusting the inner coupling between different patterns and the length of the striplines. Besides, no via-hole was used in this structure, which guarantees the easy fabrication and high production. [ABSTRACT FROM AUTHOR]

A novel ultra-wideband bandstop filter with three semi-lumped resonators based on low-temperature co-fired ceramic technology is presented. Stopband rejection depth and bandwidth are controlled by the elements of each resonator. The filter not only has controllable transmission zeros, but it also features compact size due to the low-temperature co-fired ceramic 3-D structure and meandered topology. In addition, multi-layer capacitors are employed to enlarge the capacitance without size increments. A lossless transmission line model analysis is used to derive design equations. To validate the proposed structure, a multi-layer bandstop filter centered at 3.2 GHz with bandwidth of over 85% is designed and built. Good agreement between measured and simulated results is obtained. [ABSTRACT FROM PUBLISHER]

A novel compact half-wavelength cross-coupled stepped-impendence resonator filter using low-temperature co-fired ceramic technology is presented. The size is miniaturized due to the low-temperature co-fired ceramic structure, while the stopband rejection is largely enhanced by introducing source-load coupling. A fourth-order stepped-impendence resonator filter with the first spurious response of about 2.5 times away from the center frequency is fabricated. Good agreement between measured and simulated results is observed. [ABSTRACT FROM AUTHOR]

Inductors have been produced in low-temperature co-fired ceramic in a manner that increases the cross-sectional area of the conductor. This geometry helps to compensate for high-frequency non-idealities, such as skin effect, current crowding and proximity effect. An array of various inductor geometries and probing structures has been fabricated and characterized. Qs of over 80 were confirmed, with Qs of over 100 believed to be possible. Accurate measurements of such values require careful consideration of error sources and the use of rigorous measurement techniques that are discussed. Finally, a filter has been fabricated to demonstrate the usefulness of these inductors in real-world applications. [ABSTRACT FROM PUBLISHER]

Microchannel devices were constructed from low-temperature co-fired ceramic (LTCC) materials with screen-printed gold (SPG) electrodes in three dimensions-on all four walls-for self-contained enzyme-linked immunosorbant assays with electrochemical detection. The microchannel confines the solution to a small volume, allowing concentration of electroactive enzymatically generated product and nearby electrodes provide high-speed and high-sensitivity detection: it also facilitates future integration with microfluidics. LTCC materials allow easy construction of three-dimensional structures compared with more traditional materials such as glass and polymer materials. Parallel processing of LTCC layers is more amenable to mass production and fast prototyping, compared with sequential processing for integrating multiple features into a single device. LTCC and SPG have not been reported previously as the basis for microchannel immunoassays, nor with integrated, individually addressable electrodes in three dimensions. A demonstration assay for mouse IgG at 5.0 ng/mL (3.3 × 10 M) with electrochemical detection was achieved within a 1.8 cm long × 290 μm high × 130 μm wide microchannel (approximately 680 nL). Two of four SPG electrodes span the top and bottom walls and serve as the auxiliary electrode and the assay site, respectively. The other two (0.7 cm long × 97 μm wide) are centered lengthwise on the sidewalls of the channel. One serves as the working and the other as the pseudoreference electrode. The immunoassay components were immobilized at the bottom SPG region. Enzymatically generated p-aminophenol was detected at the internal working electrode within 15 s of introducing the enzyme substrate p-aminophenyl phosphate. A series of buffer rinses avoided nonspecific adsorption and false-positive signals. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The effects of sintering process conditions on the size shrinkages of low-temperature co-fired ceramic (LTCC) substrate were investigated. The process variables investigated were thickness of the stacked raw tapes, lamination pressure, lamination-pressure holding time, pre-heating time, debinding time, sintering dwell time, and sintering temperature ramp. Results revealed that the size shrinkage percentage of the LTCC samples in the lateral directions was always smaller than that in the thickness direction. The lateral shrinkage deviations were less than 2.1% for all the experiments conducted in this study. Pre-heating time, lamination-pressure holding time, debinding time, sintering dwell time and sintering temperature ramp had almost no effects on the lateral size shrinkage of the LTCC samples, and the average of the lateral shrinkage values was 15.3%, with a standard deviation of 0.17%. Lamination pressure and stacked raw-tape thickness had effects on the lateral size shrinkage of the LTCC samples, and empirical equations for calculation of the size shrinkage values were obtained by curve fitting. [ABSTRACT FROM AUTHOR]

The advantages of a dielectric loaded double-stacked electromagnetic bandgap structure with a significantly improved noise isolation bandwidth, fabricated on a low-temperature co-fired ceramic multilayer substrate, were experimentally demonstrated in system-in-package applications. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 942–944, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23253 [ABSTRACT FROM AUTHOR]

A low-temperature co-fired ceramic (LTCC) X-band receiver front-end is designed using a novel embedded multilayer substrate integrated waveguide filter. The filter is a quasi-elliptic type, fabricated into multilayers on LTCC process, making it compact as well as of low cost and high selectivity. Simulated and experimental results of the filter and X-band receiver front-end are presented. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 285–287, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23057 [ABSTRACT FROM AUTHOR]

The broadband bandpass filter (BPF) designed with low-temperature co-fired ceramic technology has been proposed in this letter. By adopting a quadruple resonator, the broadband BPF with compact size can be fabricated. A quadruple resonator with metal-insulator-metal capacitors is employed to make inductive and capacitive couplings. The coupling scheme can create two transmission zeros at both sides of passband skirts by appropriately selecting the coupling coefficient. The center frequency and bandwidth ratio of this filter are 3.875 GHz and 50%, respectively. This filter can increase the sensitivity and linearity in the wireless communication system as well [ABSTRACT FROM PUBLISHER]

In this letter, a compact branch-line coupler is proposed by making good use of the three-dimensional layout capability of the low-temperature co-fired ceramic (LTCC) substrate. This branch-line coupler is accomplished by using lumped-inductors and lumped-capacitors to realize the modified-T equivalent-circuit model for the transmission line so that the circuit size may drastically be reduced. Specifically, a very compact LTCC branch-line coupler with a size of 0.079λ×0.0717λ is implemented and carefully examined, where λ is the wavelength of the multilayer structure at the operating frequency f0. [ABSTRACT FROM PUBLISHER]

We present the first demonstration of a CMOS power amplifier (PA) utilizing fully integrated multilayer low-temperature co-fired ceramic (LTCC) high-Q passives for 1.9-GHz digital European cordless telecommunications (DECT) applications. The inductor and capacitor library were built in a multilayer LTCC board using a compact topology. An inductor Q-factor as high as 100 with a self-resonant frequency (SRF) as high as 8 GHz was demonstrated. Measured results of the CMOS-LTCC PA show good agreement with the simulated results exhibiting 48% power added efficiency, 26-dBm output power and 17-dB gain at 1.9 GHz with a 3.3-V drain supply voltage. This result is the first significant step toward a compact DECT transceiver module development utilizing fully integrated multilayer LTCC passives and a standard CMOS technology [ABSTRACT FROM PUBLISHER]

A novel ultra-wideband (UWB) antenna realized using low-temperature co-fired ceramic (LTCC) technology is reported in this paper. The resultant antenna volume is only 17 × 8 × 0.8 mm3. Based on the measurements using a network-analyzer system, a bandwidth of 6.7 GHz is achieved (with return loss S11 < 10 dB from 3.75 to 10.45 GHz). The measured antenna radiation patterns at 6.85 GHz are also presented. © 2005 Wiley Periodicals, Inc. Microwave Opt Technol Lett 47: 608–609, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21243 [ABSTRACT FROM AUTHOR]

This paper outlines a method of tuning a microwave broadside coupler buried in low-temperature co-fired ceramic. Etching a slot in the exposed ground plane tunes the characteristic impedance Z0 of a stripline coupler. An iterative method computes the correct dimensions of the slot. Applying the method salvages microwave circuits detuned due to manufacturing tolerances [ABSTRACT FROM PUBLISHER]