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12 pages, 4651 KiB

Open AccessArticle

Synthesis and Characterization of Single-Phase α-Cordierite Glass-Ceramics for LTCC Substrates from Tuff

by Yongsheng Yu, Jinghan Wang, Yuanyuan Yu, Zhaoli Yan, Yanyan Du, Pengfei Chu, Qiangshan Jing and Peng Liu

Materials 2022, 15(24), 8758; https://doi.org/10.3390/ma15248758 - 8 Dec 2022

Cited by 1 | Viewed by 1080

Abstract

Single-phase α-cordierite glass-ceramics for a low-temperature co-fired ceramic (LTCC) substrate were fabricated from tuff as the main raw material, using the non-stoichiometric formula of α-cordierite with excess MgO without adding any sintering additives. The sintering/crystallization behavior and the various performances of dielectric properties, [...] Read more.

Single-phase α-cordierite glass-ceramics for a low-temperature co-fired ceramic (LTCC) substrate were fabricated from tuff as the main raw material, using the non-stoichiometric formula of α-cordierite with excess MgO without adding any sintering additives. The sintering/crystallization behavior and the various performances of dielectric properties, thermal expansion, and flexural strength of the glass-ceramics were detected. The results indicated that only single-phase α-cordierite crystal was precipitated from the basic glass sintered at the range 875–950 °C, and μ-cordierite crystal was not observed during the whole sintering-crystallization process. The properties of glass-ceramics were first improved and then deteriorated with the increase in tuff content and sintering temperature. Fortunately, the glass-ceramics sintered at 900 °C with 45 wt.% tuff content possessed excellent properties: high densify (2.62 g∙cm⁻³), applicable flexural strength (136 MPa), low dielectric loss (0.010, at 10 MHz), low dielectric constant (5.12, at 10 MHz, close to α-cordierite), and suitable coefficients of thermal expansion (CTE, 3.89 × 10⁻⁶K⁻¹). Full article

(This article belongs to the Special Issue Materials for LTCC Technology)

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15 pages, 13098 KiB

Open AccessArticle

Enhanced Sinterability, Thermal Conductivity and Dielectric Constant of Glass-Ceramics with PVA and BN Additions

by Dilara Arıbuğa, Ufuk Akkaşoğlu, Buğra Çiçek and Özge Balcı-Çağıran

Materials 2022, 15(5), 1685; https://doi.org/10.3390/ma15051685 - 24 Feb 2022

Cited by 4 | Viewed by 2259

Abstract

With the rapid development of the microelectronics industry, many efforts have been made to improve glass-ceramics’ sinterability, thermal conductivity, and dielectric properties, which are essential components of electronic materials. In this study, low-alkali borosilicate glass-ceramics with PVA addition and glass-BN composites were prepared [...] Read more.

With the rapid development of the microelectronics industry, many efforts have been made to improve glass-ceramics’ sinterability, thermal conductivity, and dielectric properties, which are essential components of electronic materials. In this study, low-alkali borosilicate glass-ceramics with PVA addition and glass-BN composites were prepared and successfully sintered at 770 °C. The phase composition, density, microstructure, thermal conductivity, and dielectric constant were investigated. It was shown that PVA addition contributes to the densification process of glass-ceramics (~88% relative density, with closed/open pores in the microstructure) and improves the thermal conductivity of glass material from 1.489 to 2.453 W/K.m. On the other hand, increasing BN addition improves microstructures by decreasing porosities and thus increasing relative densities. A glass-12 wt. % BN composite sample exhibited almost full densification after sintering and presented apparent and open pores of 2.6 and 0.08%, respectively. A high thermal conductivity value of 3.955 W/K.m and a low dielectric constant of 3.00 (at 5 MHz) were observed in this material. Overall, the resulting glass-ceramic samples showed dielectric constants in the range of 2.40–4.43, providing a potential candidate for various electronic applications. Full article

(This article belongs to the Special Issue Materials for LTCC Technology)

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13 pages, 9355 KiB

Open AccessArticle

Metallization, Material Selection, and Bonding of Interconnections for Novel LTCC and HTCC Power Modules

by Aleksander Sešek and Kostja Makarovič

Materials 2022, 15(3), 1036; https://doi.org/10.3390/ma15031036 - 28 Jan 2022

Cited by 6 | Viewed by 2748

Abstract

Ceramic baseplates are important elements in the power modules of electric drives. This paper presents low-temperature cofired ceramic (LTCC) and high-temperature cofired ceramic (HTCC) materials for the fabrication of three-dimensional power modules. The silver-based metallization and power module assembly are presented, together with [...] Read more.

Ceramic baseplates are important elements in the power modules of electric drives. This paper presents low-temperature cofired ceramic (LTCC) and high-temperature cofired ceramic (HTCC) materials for the fabrication of three-dimensional power modules. The silver-based metallization and power module assembly are presented, together with aluminum-based power wire bonding and an industrial procedure to achieve high solderability and bondability. The results of the bond tests using different metallization materials, especially cost-effective ones, are presented, together with the assembly of the power modules. The best results were achieved with Ag metallization and 380 µm Al wire and with Ag–Pd metallization and 25 µm Al wire, both on an LTCC base. The paper concludes with a dual-pulse electrical test of the power modules, which proves the quality of metallization, the type of material selected, and the correctness of the wire bonding and assembly. Full article

(This article belongs to the Special Issue Materials for LTCC Technology)

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10 pages, 2071 KiB

Open AccessArticle

Large Thermal Expansion LTCC System for Cofiring with Integrated Functional Ceramics Layers

by Beate Capraro, Manuel Heidenreich and Jörg Töpfer

Materials 2022, 15(2), 564; https://doi.org/10.3390/ma15020564 - 12 Jan 2022

Cited by 3 | Viewed by 1719

Abstract

We have studied the sintering behavior of CT708 LTCC tapes with large CTE of 10.6 ppm/K. This low-k dielectric LTCC material is a quartz-based glass ceramic composite system with partial crystallization of celsian upon firing. The shrinkage, densification and dielectric properties were examined [...] Read more.

We have studied the sintering behavior of CT708 LTCC tapes with large CTE of 10.6 ppm/K. This low-k dielectric LTCC material is a quartz-based glass ceramic composite system with partial crystallization of celsian upon firing. The shrinkage, densification and dielectric properties were examined using different heating rates and a sintering temperature of 900 °C. The maximum shrinkage rate is at 836 °C (for a heating rate of 2 K/min) with a sintering density of 95% and a permittivity of ε’ = 5.9 and tan δ = 0.0004 (at 1 GHz). Due to their similar shrinkage and thermal expansion properties, CT708 tapes may be cofired with functional ceramic layers. As an example, we report on cofiring of a multilayer laminate of CT708 and a Sc-substituted hexagonal ferrite for applications as integrated microwave circulator components. This demonstrates the feasibility of cofiring of functional ceramic tapes and tailored LTCC tapes and documents the potential for the realization of complex LTCC multilayer architectures. Full article

(This article belongs to the Special Issue Materials for LTCC Technology)

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15 pages, 7490 KiB

Open AccessArticle

Low-Temperature Metallization and Laser Trimming Process for Microwave Dielectric Ceramic Filters

by Jau-Jr Lin, Cheng-I Lin, Tune-Hune Kao and Meng-Chi Huang

Materials 2021, 14(24), 7519; https://doi.org/10.3390/ma14247519 - 8 Dec 2021

Cited by 4 | Viewed by 1684

Abstract

This paper describes a low-temperature metallization and laser trimming process for microwave dielectric ceramic filters. The ceramic was metalized by electroless copper plating at a temperature lower than those of conventional low-temperature co-fired ceramic (LTCC) and direct bond copper (DBC) methods. Compared with [...] Read more.

This paper describes a low-temperature metallization and laser trimming process for microwave dielectric ceramic filters. The ceramic was metalized by electroless copper plating at a temperature lower than those of conventional low-temperature co-fired ceramic (LTCC) and direct bond copper (DBC) methods. Compared with filters made via traditional silver paste sintering, the metal in the holes of the microwave dielectric filters is uniform, smooth, and does not cause clogging nor become detached. Further, the batches of fabricated filters do not require individual inspection, reducing energy, labor, cost, and time requirements. A microwave dielectric filter was then manufactured from the prepared ceramic using a laser trimming machine with a line width and position error within ±50 μm; this demonstrates a more accurately controlled line width than that offered by screen printing. After using HFSS software simulations for preliminary experiments, the microwave dielectric filter was tuned to a target Wi-Fi band of 5.15–5.33 GHz; the return loss was <−10 dB, and the insertion loss was >−3 dB. To implement the real-world process, the laser parameters were optimized. Laser trimming has a higher success rate than traditional manual trimming, and the microwave dielectric filter manufactured here verified the feasibility of this process. Full article

(This article belongs to the Special Issue Materials for LTCC Technology)

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8 pages, 2158 KiB

Open AccessArticle

A 3D LTCC-Based Ceramic Microfluidic System with RF Dielectric Heating of Liquids

by Kostja Makarovič, Darko Belavič, Matjaž Vidmar and Barbara Malič

Materials 2021, 14(23), 7396; https://doi.org/10.3390/ma14237396 - 2 Dec 2021

Cited by 3 | Viewed by 1586

Abstract

The design, fabrication and functional evaluation of the radio-frequency dielectric heating of liquids in an LTCC-based ceramic microfluidic system are described and discussed. The device, which relies on the dielectric heating of liquids, was fabricated using a low temperature co-fired ceramic (LTCC) technology. [...] Read more.

The design, fabrication and functional evaluation of the radio-frequency dielectric heating of liquids in an LTCC-based ceramic microfluidic system are described and discussed. The device, which relies on the dielectric heating of liquids, was fabricated using a low temperature co-fired ceramic (LTCC) technology. A multilayered ceramic structure with integrated electrodes, buried channels and cavities in micro and millimetre scales was fabricated. The structure with the dimensions of 35 mm × 22 mm × 2.4 mm includes a buried cavity with a diameter of 17.3 mm and a volume of 0.3 mL. The top and bottom faces of the cavity consist of silver/palladium electrodes protected with 100 μm thick layers of LTCC. The power, used to heat a polar liquid (water) in the cavity with the volume of 0.3 mL, ranges from 5 to 40 W. This novel application of RF dielectric heating could enable the miniaturization of microfluidic systems in many applications. The working principle of such a device and its efficiency are demonstrated using water as the heated medium. Full article

(This article belongs to the Special Issue Materials for LTCC Technology)

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11 pages, 4066 KiB

Open AccessArticle

Structural, Thermal and Dielectric Properties of Low Dielectric Permittivity Cordierite-Mullite-Glass Substrates at Terahertz Frequencies

by Beata Synkiewicz-Musialska, Dorota Szwagierczak, Jan Kulawik, Norbert Pałka and Przemysław Piasecki

Materials 2021, 14(14), 4030; https://doi.org/10.3390/ma14144030 - 19 Jul 2021

Cited by 10 | Viewed by 1998

Abstract

Glass–ceramic composites containing cordierite, mullite, SiO₂ glass and SiO₂-B₂O₃-Al₂O₃-BaO-ZrO₂ glass were fabricated in a process comprising solid state synthesis, milling, pressing and sintering. Thermal behavior, microstructure, composition and dielectric properties in [...] Read more.

Glass–ceramic composites containing cordierite, mullite, SiO₂ glass and SiO₂-B₂O₃-Al₂O₃-BaO-ZrO₂ glass were fabricated in a process comprising solid state synthesis, milling, pressing and sintering. Thermal behavior, microstructure, composition and dielectric properties in the Hz-MHz, GHz and THz ranges were examined using a heating microscope, differential thermal analysis, thermogravimetry, scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction analysis, impedance spectroscopy, transmission method and time domain spectroscopy (TDS). The obtained substrates exhibited a low dielectric permittivity of 4.0–4.8. Spontaneously formed closed porosity dependent on the sintering conditions was considered as a factor that decreased the effective dielectric permittivity. Full article

(This article belongs to the Special Issue Materials for LTCC Technology)

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14 pages, 5755 KiB

Open AccessArticle

LTCC and Bulk Zn₄B₆O₁₃–Zn₂SiO₄ Composites for Submillimeter Wave Applications

by Dorota Szwagierczak, Beata Synkiewicz-Musialska, Jan Kulawik and Norbert Pałka

Materials 2021, 14(4), 1014; https://doi.org/10.3390/ma14041014 - 21 Feb 2021

Cited by 15 | Viewed by 2107

Abstract

New zinc metaborate Zn₄B₆O₁₃–willemite Zn₂SiO₄ composites were investigated as promising materials for LTCC (low temperature cofired ceramics) substrates of microelectronic circuits for submillimeter wave applications. Composites were prepared as bulk ceramics and LTCC multilayer [...] Read more.

New zinc metaborate Zn₄B₆O₁₃–willemite Zn₂SiO₄ composites were investigated as promising materials for LTCC (low temperature cofired ceramics) substrates of microelectronic circuits for submillimeter wave applications. Composites were prepared as bulk ceramics and LTCC multilayer structures with cofired conductive thick films. The phase composition, crystal structure, microstructure, sintering behavior, and dielectric properties were studied as a function of willemite content (0, 10, 13, 15, 20, 40, 50, 60, 100 wt %). The dielectric properties characterization performed by THz time domain spectroscopy proved the applicability of the composites at very high frequencies. For the 87% Zn₄B₆O₁₃–13% Zn₂SiO₄ composite, the best characteristics were obtained, which are suitable for LTCC submillimeter wave applications. These were a low sintering temperature of 930 °C, compatibility with Ag-based conductors, a low dielectric constant (5.8 at 0.15–1.1 THz), a low dissipation factor (0.006 at 1 THz), and weak frequency and temperature dependences of dielectric constant. Full article

(This article belongs to the Special Issue Materials for LTCC Technology)

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