We have successfully demonstrated the inkjet printing method to create Al2O3 films without a high temperature sintering process. In order to remove the coffee ring effect in the ink drop, we have introduced a co-solvent system in order to create Marangoni flow in the ink drop, which leads to the dense packing of ceramic powders on the substrate during inkjet process. The packing density of the Inkjet-printed Al2O3 films is around 60% (max. 70%) which is very high compared to the value obtained from the same material films by other conventional methods such as film casting, dip coating process, etc. The voids inside the films (which are around 40% of the entire film volume) are filled with the polymer resin (Cyanate ester) by the infiltration process. This resin infiltration is also implemented by the inkjet printing process right after the Al2O3 film ink-jetting process. The microstructures of the printed Al2O3 films are investigated by Scanning Electron Microscope (SEM) to understand the degree of packing density in the printed films. The inkjet-printed Al2O3 films have been characterized to investigate its thickness and roughness. Quality factor of the printed Al2O3 film is also measured to be over 300 at 1MHz.

The physical and chemical state of ceramics are very important for their microwave dielectric properties, especially at high frequencies above GHz. Therefore, the microstructure and microwave dielectric properties of (1-x)Mg(Zr0.05Ti0.95)O3–xSTiO3((1-x)MZT–xST) ceramics were investigated by controlling external variables. The compounds were synthesized through a solid-state reaction mechanism and sintered at relatively low temperatures. A cavity resonator method was employed to analyze the microwave dielectric properties. Optimal sintering conditions significantly enhanced the microwave dielectric performance of MZTST ceramics. The addition of ZnO substantially reduced the sintering temperature and equilibrium sintering time, enabling the activation of optimal conditions and the achievement of temperature-stable microwave dielectrics like NP0: εr ~20.16 at 10GHz, Qf of ~81839GHz at 7.93GHz, and τf close to zero (~0.12 ppm/oC). This enhanced performance was attributed to the optimization of internal variables, including enhanced relative density, homogeneous grain size, optimal phase fraction, and chemical ordering.

(1-x)LaGaO3-xSrTiO3 (x = 0-0.6) microwave dielectric ceramics were synthesized by using conventional solid-state reaction method and sintered at 1450 degrees C with different sintering conditions. The variations of micro-structure, relative density, and phase formation were observed by different composition and sintering conditions. The microwave properties, such as permittivity/dielectric constant (epsilon r), quality factor (Qf), and temperature coefficient of resonant frequency (TCF, tau f) at a high frequency were investigated in terms of lattice distortion, chemical ordering, and chemical homogeneity according to the composition and equilibrium sintering condi-tions. A maximum Qf-64,900 GHz was observed at x = 0, and the best tau f -0 ppm/degrees C was obtained at x = 0.4. Consequently, it was found that the permittivity is related mainly to the lattice distortion, whereas the quality factor is primarily affected by chemical ordering and chemical homogeneity of the microstructure-induced composition.

LaAlO3-BaSnO3 ceramics as a new microwave dielectric material were investigated in terms of optimum synthesis conditions and thereby the relative density, microstructure, solid-solution state, and dielectric properties with the addition of various sintering aids at different sintering temperatures. The dielectric properties of 0.9LaAlO(3)-0.1BaSnO(3) (LA-0.1BS) were strongly influenced by relative density, microstructure, chemical ordering, and mixing rule of the dielectric constant. Densification of the LA-0.1BS ceramics was improved from 82.3 to 96.13% with an average grain size of around 1.9 mu m at reduced sintering temperature by 250 degrees C. The LA-0.1BS ceramics sintered with 3 mol% of Bi2O3-SiO2 (BS) showed dielectric constant (epsilon(r)) similar to 21.18 with associated dielectric loss (tan delta) similar to 0.00824 and Q x f similar to 1213.59 (10 GHz) which could be achieved at low sintering temperature of 1400-1450 degrees C.

The Mo-based glass-free spinel-type structure of the (Na1-xKx)(2)MoO4 (x = 0.0, 0.1, and 0.2) ceramic series was prepared using the traditional solid-state method at the low sintering temperature (<650 degrees C). The microwave dielectric properties of the (Na1-xKx)(2)MoO4 series were determined in terms of phase compositions, crystal structure (via XRD), and microstructure analysis (via FE-SEM and EDS). The results revealed that the double-phase (cubic and orthorhombic) formation plays a significant role in the entire (Na1-xKx)(2)MoO4 series. It exhibits excellent dielectric properties: dielectric constant epsilon(r) = 4 (1 GHz)/3.77 (15 GHz), tangent loss tan delta = 8.3 x 10(-2) (1 GHz)/7 x 10(-3) (15 GHz; Q x f = 2143 GHz), temperature coefficient of frequency (TCF) tau(f) = -6.45 ppm/degrees C, and room temperature thermal conductivity (kappa) = 1.76 W/(m.K) for x = 0.1 at a sintering temperature of 575 degrees C. These make the (Na1-xKx)(2)MoO4 ceramic series a potential candidate for low-temperature co-fired ceramic (LTCC) substrate applications (as used in antennas) for high-speed data communications.

Abstract The demand for high thermal conductivity substrates with electrically insulating materials are increasing with the emerging markets in power electronics and mobile telecommunication device packages. Effective heat transfer in those packages is important to provide high performance and reliability of the product. This paper mainly presents the thermophysical properties of zirconia toughened alumina ceramics with the addition of small amount of boron nitride nanotubes (BNNTs). The effects of the boron nanotubes addition on the sintering behavior, the microstructure and the thermal properties of the yttria-stabilized zirconia toughened alumina (YZTA), nanocomposite ceramics are investigated. The addition of 0.3 wt% boron nitride nanotubes into the YZTA matrix enhanced the thermal diffusivity as well as a mechanical strength. Above all, the addition of boron nitride nanotubes greatly decreased the coefficient of thermal expansion (CTE) of the composites in which the CTE of pure alumina increases with increasing temperatures. Moreover, the BNNTs added YZTA composites revealed a drastic decrease in CTE at high temperature range, 400–800 °C. This enhanced thermal stability of YZTA–BNNT composites may have a potential application to the high temperature structural ceramics and high power semiconductor packaging substrate.

Bivalent calcium metavanadate (CaV2O6) ceramic-glass composite substrates were fabricated using non-aqueous environmental friendly tape casting formulation. 3 wt% of commercial glass was added to the calcined powder of CaV2O6 to achieve a sintering temperature of 650 °C which enables ultra-low temperature co-firing with aluminum electrode. An environmentally benign binder/solvent (Polypropylene carbonate/dimethyl carbonate) system was adopted to prepare the well dispersed slurry for tape casting. The crystal structure and co-fireability of the sintered substrate with Al was verified by X-ray diffraction technique. Thermal, dielectric and morphological analysis of the multilayer were analyzed. The room temperature thermal conductivity of CaV2O6-glass composite sintered at 650 °C is about 2.8 W/m K. Sintered ceramics shows a relatively high linear coefficient of thermal expansion (CTE) of 11.46 ppm/°C, which is favorable for co-firing with high CTE metallic materials. Microwave dielectric properties of CaV2O6-glass composite multilayer fired at 650 °C are εr = 10.6 and tanδ = 3.19 × 10−4 at 15 GHz.

A CaO-B2O3-SiO2 (CBS) glass/40wt% Al2O3 composite sintered at 900 degrees C exhibited a dense microstructure with a low porosity of 0.21%. This composite contained Al2O3 and anorthite phases, but pure glass sintered at 900 degrees C has small quantities of wollastonite and diopside phases. This composite was measured to have a high bending strength of 323MPa and thermal conductivity of 3.75W/(mK). The thermal conductivity increased when the composite was annealed at 850 degrees C after sintering at 900 degrees C, because of the increase in the amount of the anorthite phase. 0.25wt% graphene oxide and 0.75wt% multi-wall carbon nanotubes were added to the CBS/40wt% Al2O3 composite to further enhance the thermal conductivity and bending strength. The specimen sintered at 900 degrees C and subsequently annealed at 850 degrees C exhibited a large bending strength of 420MPa and thermal conductivity of 5.51W/(mK), indicating that it would be a highly effective substrate for a chip-type supercapacitor.

Ultra-low-temperature co-fireable Li2WO4 substrate has been developed using an environmental friendly tape-casting technique. The nonaqueous tape-casting slurry comprised of an eco-friendly binder-solvent system consisting of polypropylene carbonate as binder and dimethyl carbonate as solvent. The structural, thermal, morphological, rheological, and electrical properties of the sintered substrate is investigated. The bulk ceramics sintered at 650 degrees C possess a relatively high thermal expansion coefficient of about 16 ppm/degrees C. The thermal conductivity of sintered tape measured at room temperature was about 2.6 W/m.K. The sintered substrate exhibits excellent microwave dielectric properties with a relative permittivity of 5.4 and a very low dielectric loss of 9.21 x 10(-5) at 5 GHz and is co-fireable with Ag electrode.

Recently, ceramic substrates have been of great interest for use in light emitting diode (LED) packaging materials because of their excellent heat transfer capability. The thermal conductivities of ceramic-based substrates are usually one or two orders of magnitude higher than those of conventional epoxy-based substrates. The demand for ceramic substrates with high mechanical strength and thermal conductivity is also growing due to their use in thin and high-power device packaging substrates. Examples are direct bonded copper or aluminum or direct plated copper substrates for insulated gate bipolar transistors; thin and robust ceramic packages for image sensor modules that are used in mobile smart phones; ceramic packages for miniaturized chip-type supercapacitors; and high-power LED packages. This chapter will cover the development and application of ceramics and ceramic composites with high thermal conductivity for the thermal management of integrated electronic packaging substrates such as high-power LED packaging, power device packaging, etc.

One-dimensional (1-D) Ag arrays were formed by electrohydrodynamic jet-printing (EHD) of polyvinylpyrrolidone (PVP, 1,300 k, Aldrich) solution ink. The 1-D Ag arrays were formed on slide glass by controlling the viscosity and printing conditions such as the tip to the substrate distance, the applied voltage, the flow rate of ink and the velocity. The printed pillars were dried at 80 °C to get rid of the solvent and sintered at 400 °C for 30 min. We found that the arrays of Ag pillars can be fabricated by using the EHD printing method. We could control the diameter of the pillars in the range of 100–200 μm and the length rage between 300 and 700 μm. In order to produce a better performance of glucose sensor, we infiltrated a glucose oxidase as a glucose detector into the Ag pillars previously coated with the mixed solution of multi-walled carbon nanotube (MWCNT, Iljin), Nafion and Pt nanoparticles. In addition, the Ag array electrode with glucose oxidase was used as a working electrode for glucose detection via the three-electrode electrochemical method.

Greater strength and thermal conductivity of component parts of portable electronic devices are increasingly required due to the increased degree of integration and the shock factor as a result of mobility. In this regard, it is necessary to conduct research to improve the physical properties using crystallized glass or alumina filters. This study focused on the identification of regions where anorthite glass, anorthite crystals, diopside crystals, and alumina phase coexist. It was observed that not only did Al2O3 react with anorthite-system glass and create anorthite crystals in the course of sintering, but it also reacted with the diopside phase and generated MgAl2O4. However, when the average particle diameter of Al2O3 was relatively large, at 3.5 mu m, MgAl2O4 was not created following the addition of 23% Al2O3 or less. As a result of the evaluation of the strength and thermal conductivity, it was found that both physical properties rapidly fell when the 2nd-phase MgAl2O4 was generated.

: Ceramic-metal based high power LED array package was developed via thick film LTCC technology using a glass-ceramic insulation layer and a silver conductor patterns directly printed on the aluminum heat sink substrate. The thermal resistance measurement using thermal transient tester revealed that ceramic-metal base LED package exhibited a superior heat dissipation property to compare with the previously known packaging method such as FR-4 based MCPCB. A prototype LED package sub-module with 50 watts power rating was fabricated using a ceramic-metal base chip-on-a board technology with minimized camber deformation during heat treatment by using partially covered glass-ceramic insulation layer design onto the aluminum heat spread substrate. This modified circuit design resulted in a camber-free packaging substrate and an enhanced heat transfer property compared with conventional MCPCB package. In addition, the partially covered design provided a material cost reduction compared with the fully covered one.

Low Temperature Co-fired Ceramics (LTCC) are widely used in electronic devices due to their ease of layering and outstanding applicability to RF technologies. These LTCC parts are manufactured by thick film process. However, unlike electronic devices of the past, modern portable electronic devices now require high strength materials, and LTCCs, which have a mixed glass and crystal phase, are relatively low strength materials. Thus their strength has been enhanced with crystallized glass induced by low temperature sintering. The most commonly used crystal phase is anorthite, but there is a comparative lack of research on other crystal phases or mixed phases and their strengths. Thus this study observed and compared the physical properties of mixed phases of synthesized anorthite and diopside at varying proportions. The two crystal phases were synthesized at the respective temperatures of 1300 degrees C and 1250 degrees C and as there was almost no change in the phases caused by the sintering process, mixed phases of varying proportions could be produced. The flexural strength of the sintered mixed phases increased along with the amount of anorthite but decreased for 100% anorthite. The decrease in flexural strength was judged to be caused by the presence of glass phase. This was tested by comparing the flexural strength and microstructure of sintered anorthite having varying Al2O3 content. This enabled us to confirm indirectly that the glassy phase was the cause of decreased flexural strength.

The microstructures of real nanomaterials can be quite complex with variety of grain sizes aligned in different crystal orientations and structural defects possibly created in a fabrication process. Material properties of these polycrystalline materials are generally known strongly dependent on the nanoscale morphology. First principle calculations based on the density functional theory need to be employed in these atomic characterizations; however, it may not be suitable for the polycrystalline nanomaterials for which large number of atoms is required in the simulation model. Instead, a mesoscale computer simulation scheme is employed to investigate these morphology-dependent mechanical properties of polycrystalline materials. We demonstrated the Voronoi construction of various polycrystalline atomic models such as two-dimensional graphene and three-dimensional silicon carbide. General behavior of the mechanical characteristics of the bulk nanostructured silicon carbide (SiC) was addressed, particularly the contribution of grain sizes. From this study, the optimal grain size was determined near 10 nm under tensile and compressive deformations.

A DEP device with a transparent oxide thin film electrode was fabricated by a photolithography process and sputtering deposition with indium tin oxide (ITO). In order to form a fine ITO electrode pattern, we manipulated the negative slope using a photoresist by controlling the intensity of the ultra-violet radiation and the exposure time. In this study, the motions of a 1 microm polystyrene sphere and TiO2 nanotube were observed as a function of the applied voltage and the frequency. The findings confirm that TiO2 nanotubes can be manipulated by a p-DEP force and that they can be effectively aligned under conditions of 10 V(p-p) at 750 Hz.

Hybrid Magnetic films composed of Fe3O4 powders and epoxy resin were fabricated by inkjet printing process. Through the optimization of Fe3O4 ink and inkjet parameters, the Fe3O4 films were formed with the thickness from 5 to 100 mu m. The film thickness Could be adjusted by varying the solid content of Fe3O4 ink and repeating the number of inkjet printing of the Fe3O4 ink. To obtain a rigid magnetic film epoxy resin was infiltrated into the Fe3O4 film and subsequently cured at 250 degrees C. It was the confirmed that highly-packed Fe3O4 hybrid film could be formed without any macro-voids after epoxy resin infiltration The magnetic permeability and loss of hybrid Fe3O4 films with different film thickness were measured and those values at 13.56 MHz were compared Magnetic properties of inkjet-printed Fe3O4 hybrid-film was improved as the film thickness increased Magnetic permeability and loss of Fe3O4 hybrid film with 30 mu m thickness were 9.9 and 5.9 respectively.

A ceramic-based microfluidic biochip for the application to separate the magnetic particles in the continuous flow was fabricated. To realize the various functions in a biochip passive mixer, passive filter and active separator was integrated. Active separation was performed by external permanent magnet. A ceramic-based microfluidic chip was fabricated by LTCC (low temperature co-fired ceramic) process combined with photolithography. Through the addition of photosensitive polymer into LTCC slurry, it was possible to form a microchannel in a ceramic body by UV photolithography. To realize the magnetic separation under the applied magnetic field in a continuous flow, the separation chamber was designed to have multi-channel system with different channel width. To check the performance of a ceramic-based microfluidic device, microfluidic parameters were optimized considering both the hydrodynamic and magnetic force of the ceramic-based chip.