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Ceramics International xxx (xxxx) xxx–xxx Contents lists available at ScienceDirect Ceramics International journal homepage: doc.001pp.com/locate/ceramint Silver di?usion and mechanism of CaO-MgO-SiO2 glass ceramics in millimeter-wave properties Kuei-Chih Fenga,∗, Ming-Wei Chua, Chun-An Lub, Yoshiyuki Iizukac, Pin-Yi Chena, Chi-Shun Tud, Cheng-Sao Chene, R.R. Chiena, Chung-Ya Tsaof a Department of Mechanical Engineering, Ming Chi University of Technology, New Taipei City, 24301, Taiwan b Material and Chemical Research Laboratories, Industrial Technology Research Institute, Hsinchu City, 31040, Taiwan c Institute of Earth Sciences, Academia Sinica, Taipei, 115, Taiwan d Department of Physics, Fu Jen Catholic University, New Taipei City, 24205, Taiwan e Department of Mechanical Engineering, Hwa Hsia University of Technology, New Taipei City, 23567, Taiwan f Prosperity Dielectrics Corporation, Taoyuan, 33860, Taiwan ARTICLE INFO Keywords: LTCC Glass ceramic Silver di?usion Millimeter-wave dielectric ABSTRACT Glass ceramics have demonstrated excellent millimeter-wave dielectric properties for low-temperature-co-?redceramic (LTCC) devices applied in the 5G communication. This study highlights silver (Ag)-di?usion mechanism and millimeter-wave dielectric properties of CaO-MgO-SiO2 glass ceramics co-?red with Ag electrode near nucleation temperatures. Ag di?usion and elemental inter-di?usion occur during the endothermic-exothermic process near nucleation temperatures (~820 °C), where Ag di?used into the glass-ceramic matrix and resided around the diopside-phase grain boundaries while other metal elements (Zn, Mg, and Al) di?used into the Ag layer. Oxygen ions can ?ee from the glass-ceramic network above glass transition temperature during the endothermic process and react with the Ag ions to form the Ag-O bonds. The low dielectric dissipation in the millimeter-wave range remains after Ag di?used into the matrix. However, conductivity of Ag-electrode layer decreases at a GHz frequency due to the inter-di?usion elements with lower electric conductivities. 1. Introduction Recent telecommunication and satellite broadcasting technologies have generated a great demand for microwave and millimeter frequency ceramic components with low dielectric constants (usually εr ~ 4-9) [1,2]. Low-temperature co-?red ceramics (LTCCs) have been extensively explored in recent development of microelectronic materials to acquire low dielectric constants. Two major methods have been employed in the LTCC synthesis process. The ?rst is to use the glass matrix mixed with the dielectric ?ller such as Al2O3 and SiO2. The typical materials for commercial LTCC substrates are Ferro-L8M and NEG-MLS22 [3]. The commercial LTCC materials for antenna or LTCC substrates require low dielectric constants (εr < 10) and low dissipation factors at megahertz (MHz) range. However, the traditional LTCCs materials contain glass in matrix, which would absorb the microwave power and reduce the quality factor at microwave frequencies [4]. To improve microwave properties, the second method uses partially crystalline glass frits to produce glass ceramics with low dielectric constants and high quality factors. For example, the CaO-SiO2-B2O3 (CSB), wollastonite, cordierite and diopside glass ceramics have lower tangent losses in the gigahertz (GHz) range [5–8]. In our previous study, the CaO-MgO-SiO2 glass ceramics exhibit low dielectric constants, high quality factors at GHz range and the zero-temperature coe?cient of resonant frequency (TCF) [9–12]. Thus, the glass ceramics are promising candidates for ?lters and LTCC packages in the microwave and millimeter-wave range. In the LTCC manufacturing process, the high-conductivity electrodes (such as Ag) have been used in LTCC substrates and modules. Ag has been chosen as the electrode for the internal conductor in the multilayer devices due to its low resistivity [13,14]. However, Ag diffusion in the matrix of LTCC materials still remains a concern. Oxidation and migration of metal electrodes can occur during the co-?red sintering process. Ag di?usion can result in current leakage and thus decrease reliability of LTCC components [15]. Ag di?usion behaviors in the Al2O3- and SiO2-added glass matrix have been examined in the commercial LTCC substrates [16,17]. Hsi et al. reported that the addition of SiO2 can reduce the di?usion of Ag ions in the commercial LTCC glass chips [16]. In our previous study, the percolation clusters of ∗ Corresponding author. E-mail address: kwechin@mail.mcut.edu.tw (K.-C. Feng). https://doi.org/10.1016/j.ceramint.2019.11.007 Received 30 September 2019; Received in revised form 31 October 2019; Accepted 1 November 2019 0272-8842/ © 2019 Elsevier Ltd and Techna Group S.r.l. All rights reserved. Please cite this article as: Kuei-Chih Feng, et al., Ceramics International, https://doi.org/10.1016/j.ceramint.2019.11.007 K.-C. Feng, et al. Ceramics International xxx (xxxx) xxx–xxx Fig. 1. (a) DSC results (heating rate = 15 °C/min). (b) Densities & shrikage, and (c) XRD patterns of CaMgSi2O6 sintered at di?erent temperatures (780–870 °C) for 2 h. Microstructures of CaMgSi2O6 sintered at (d) 780 °C (e) 800 °C (f) 810 °C (g) 820 °C (h) 830 °C (i) 850 °C (j) 870 °C. broken bonds and formation of Ag-O bonds were proposed for the reduced Ag di?usion in the SiO2-added glass matrix [17]. Though Ag di?usion has been explored in the commercial LTCC materials, the di?usion mechanism in the Ag co-?red glass ceramic system still remains unclear. This work highlights the Ag-di?usion mechanism and dielectric properties in the microwave and millimeterfrequency range in the CaMgSi2O6 glass ceramics co-?red with Ag electrode. 1.1. Experimental procedures Diopside CaMgSi2O6 (CMS) glass ceramics were prepared through oxide mixing, melting, cooling, pulverizing and heat treatments. CaCO3 (> 99%, Komoshina, Japan), Mg(OH)2 (> 99%, Ube, Japan) and SiO2 (> 99%, Sibelco, Taiwan) powders were mixed in a speci?c molar ratio of 1:1:2. Subsequently, 8 mol% of ZrO2 agents (> 99.5%, Daiichi, Japan) was added as a nucleating agent, and 5 mol% ZnO and 5 mol% Al2O3 were added to enhance dielectric properties. The resulting powders were melted at 1500 °C for 2 h and then were quenched in deionized water. The quenched sand were pulverized and milled with binder, plasticizer and dispersant to fabricate tapes with thickness of 30 ± 1 μm. Tapes were then laminated before co-?red with Ag electrode (~20 μm) in the range of 800–900 °C for 2 h. Nucleation temperatures and crystal growth were determined using di?erential thermal analysis (DTA) (TA instruments). Compositions of as-sintered tapes were analyzed using electron-probe micro-analyzer (EPMA; JEOL JXA-8500F) and wavelength-dispersive spectroscopy (WDS; EDAX Co.). Microstructures were inspected using transmission electron microscopy (JEOL TEM-2100) equipped with an energy dispersive spectroscope (TEM-EDS). Phase identi?cations of the annealed glass frits and as-sintered pellets were carried out using an X-ray diffractometer (Bruker D2 Phaser) with the CuKα1 radiation (wavelength = 1.5406 Å). Raman spectra were collected using a microRaman instrument (Nanobase XperRam200) equipped with a 532 nm 2 K.-C. Feng, et al. Ceramics International xxx (xxxx) xxx–xxx Fig. 2. Rietveld re?nements of as-sintered CaMgSi2O6 specimens. “Amrp.” indicates the amorphous contents. dielectric resonator method [19,20]. 2. Results and discussion Fig. 3. (a) Diopside glass-ceramic co-?red with Ag electrode at 870 °C, (b) specimen after polishing the Ag-electrodes surface, (c) sintered LTCC (as a substrate) with post-?red Ag paste on the surface, and (d) specimen after polishing the Ag-electrode surface. green laser. The millimeter-wave dielectric properties were measured using a network analyzer 3739B (Anritsu). Dielectric constant and loss were evaluated at 30–90 GHz using a dielectric resonator technique based on the Fabry-Perot 内容过长，仅展示头部和尾部部分文字预览，全文请查看图片预览。 s. 10 (2010) 379–385. [23] FIZ Karlsruhe International Crystal Structure Data (ICSD). Karlsruhe, Germany, (2000). [24] A. Kern, Hochtemperatur-Rietveldanalysen: Möglichkeiten und Grenzen, Heidelberger Geowiss, Abhath 89 (1998) 323. [25] M.I. Ojovan, Viscosity and glass transition in amorphous oxides, Adv. Condens. Matter Phys. 817829 (2008) 23. [26] K. Fuchs, The conductivity of thin metallic ?lms according to the electron theory of metals, Math. Proc. Camb. Philos. Soc. 34 (1938) 100–108. 7 [文章尾部最后500字内容到此结束,中间部分内容请查看底下的图片预览]请点击下方选择您需要的文档下载。

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