Low-temperature Sintering Process Research Articles

Low-Temperature Sintering with Nano-Silver Paste in Die-Attached Interconnection

Traditional materials used in chip-level interconnections are not compatible with the high-temperature operation of wide-bandgap high-power semiconductor devices; therefore, this paper studies sintered nano-silver as a novel interconnect material mounting semiconductor devices onto metallized substrates. A low-temperature sintering process was employed in the preparation of a sintered nano-silver die-attachment. The physical mechanisms in volatilization and burnout of the added organic components employed in nano-silver paste were analyzed primarily by thermal gravimetric analysis (TGA) to obtain a reasonable temperature-controlling profile. The shear strength of sintered nano-silver joints was investigated, and the evolution of microstructure in the nano-silver paste sintering process was observed using a scanning electron microscope (SEM) in this process. The effects of sintering temperature, heating rate, and holding time during the sintering process were analyzed according to the densification mechanism. The microstructural observations and shear strength tests showed that a sintering temperature of 285°C, heating rate of 10°C/min, and holding time of 60 min were the best conditions for using this kind of silver paste.

Low-temperature sintering mechanism on uranium dioxide

Based on a point defect model, the mechanism of low-temperature sintering of uranium dioxide was studied in this paper. The diffusion coefficient of uranium in UO2 + x, sintering temperature and densification equation in low-temperature sintering were analyzed by both the point defect model and low-temperature sintering experiments. The results showed that the diffusion activation energy of uranium in over-stoichiometric UO2 + x was lowered by 3.0 ev than that in stoichiometric UO2. And the diffusion coefficient of uranium in UO2 + x was proportional to x2. In addition, the theoretical low temperature sintering temperature was calculated to be in the range of 1089–1151 °C, which indicated that it was necessary to maintain proper over-stoichiometric oxygen for low-temperature sintering process. Moreover, the calculation results by the point defect model matched perfectly with the experiment results, PDM might be a good model to describe the relationships between defects concentration and atmosphere composition.

Large bulk polarization and regular domain structure in ceramic BiFeO3

Regularly twinned domain structures are observed by scanning piezoforce microscopy on single crystalline grains of BiFeO3 ceramics being grown by a special low temperature sintering process. The domains are considerably larger than those observed in thin films. Their spontaneous polarization comes close to that predicted theoretically and overcomes restrictions hitherto being set to bulk single crystals. The observed ferroelastic twin domain structure resembles that of classic T domains in rhombohedrally distorted NiO, but is additionally superimposed by ferroelectric twin domain patterns.

Structural and Electrical Properties of Low Temperature Sintered Li2CO3 Doped (Ba,Sr)TiO3 Ceramics

In this paper, we present the results of the fabrication and characterization of Li2CO3 doped (Ba,Sr)TiO3 ceramics for the low temperature sintering processes. In these days, low temperature sintering process has been widely spread out for the integrated electronic modules for the communication systems such as front-end modules, antenna modules, and switching modules. Generally it is believed that low temperature sintering process can be applied to the functional materials if they can be sintered less than 900 °C. However, BaSrTiO3 materials for the tunable microwave devices applications have relatively high sintering temperature of 1350 °C. Therefore, in this study to obtain low sintering temperature, we have added 1–5 wt % of Li2CO3 to BaSrTiO3 materials to reduce the sintering temperature from 1350 to around 900 °C.

Development of Ferrite Magnetic Materials with High Strength by a Low-Temperature Sintering Method

Magnetite (Fe3O4) ferrite magnetic materials have attracted attention arising by the chip coil electronic material. However, its industrial applications have been limited by the need for high temperature sintering under reduced pressure or vacuum. In order to develop the process method of low-cost and energy saving with high-strength and high magnetism of the magnet, in this paper, a new low-temperature sintering method using CO2 gas and adding a small amount of boric acid (H3BO3) is proposed. Here, the super fine magnetite powder was fabricated by decomposition from ferrous oxalate at 500 in CO2 gas. The ferrous oxalate was synthesized using iron chloride and ammonium oxalate through liquid phase precipitation. The magnetite powder compact was produced by Newton press and CIP (cold isostatic press) after adding a small amount of boric acid. In this study, the effects of the additive on the mechanical and magnetic properties of the sintered magnet were also evaluated. By characteristic evaluation of the magnet, the validity of the proposed new low-temperature sintering process and the optimal process conditions were confirmed.

A novel low temperature sintering process for PMnN-PZT ceramics

Samples with the composition of 0.07Pb(Mn 1/3Nb 2/3)O 3–0.468PbZrO 3–0.462PbTiO 3 was prepared in this study. A novel process was adapted to lower the sintering temperature without properties deterioration. The sintering process includes a vacuumed heating stage, a air-venting heating stage, and a final sintering at 1050 °C with certain holding time without PbO compensating atmosphere. The influence of holding time at the final sintering stage on the characteristics of the ceramics was studied. The air-venting stage caused a large shrinkage (about 10%) and then slowing down the shrinking rate when the sample was heated up from 800 to 1050 °C. The relationships between the crystalline characteristics and physical properties, such as microstructure, the mechanical quality factor ( Q m), and electromechanical coupling factor ( k p), are discussed in this paper.

LOW TEMPERATURE SINTERING OF Li2CO3 ADDED (Ba,Sr)TiO3 CERAMICS

ABSTRACT In this paper, we present the results of the fabrication and characterization of Li2CO3 doped (Ba, Sr)TiO3 ceramics for the low temperature sintering processes. In these days, low temperature sintering process has been widely spread out for the integrated electronic modules for the communication systems such as front-end modules, antenna modules, and switching modules. Generally it is believed that low temperature sintering process can be applied to the functional materials if they can be sintered less than 900°C. However, BaSrTiO3 materials for the tunable microwave devices applications have relatively high sintering temperature of 1350°C. Therefore, in this study to obtain low sintering temperature, we have added 1∼5 wt % of Li2CO3 to BaSrTiO3 materials to reduce sintering temperature from 1350°C to around 900°C. In this paper, we will report the crystalline and electrical properties of Li2CO3 added BaSrTiO3 materials for the low sintering temperature applications.

Magnetostriction of Polycrystalline Strong-Textured Fe–17 at%Ga Laminates

Magnetostrictive bulk Fe–17 at%Ga alloy was fabricated by combining laminates of rapid-solidified ribbons (80 μm in thickness) using the spark plasma sintering/joining (SPSJ). The SPSJ is characterized by a short time, low temperature heating and sintering process. The laminated sample made by the SPSJ maintained a unique metallurgical microstructure of polycrystalline texture of columnar grains, as well as the almost non-equilibrium metastable phase with little evidence of the precipitates of the ordered phases as found in the as-spun ribbons. An excellent sintered sample exhibiting large magnetostriction was obtained under a condition of compressive stress of 100 MPa at a temperature of 973 K. The magnetostriction depended on compressive pre-stress level for each specimen and reached about 100 ppm, which was half the value obtained for the ribbon sample. Furthermore, by subjecting this specimen to a short annealing process, the magnetostriction increased to 170 ppm, comparable to the value for the ribbon.

Nanostructured barium titanate ceramics

Dense nanocrystalline ceramics can be obtained starting from non-agglomerated nanopowders and using low-temperature sintering processes. The preparation and the properties of Barium Titanate (BaTiO 3) ceramics and thick films are reported: ceramics were prepared by Spark Plasma Sintering (SPS) at 800 °C of nanopowders produced by a wet chemical process, while films were fabricated by airflow deposition (AD) of mixed fine and coarse powders at room temperature followed by isothermal firing. Ferroelectric ordering was found in both the ceramics and the sintered films by a.c. impedance. The transition from ferroelectric to paraelectric state was broadened over a wide temperature range with Curie–Weiss parameters strongly depressed in comparison to coarse-grained ceramics.

Swelling behavior in reactive sintering of Fe–Al mixtures

Sintering is generally recognized as a consolidation process of the powder compacts. However, the swelling problem is always observed in a stress-free reactive sintering of iron–aluminum elemental powder mixtures. Present study on the stress-free vacuum sintering of Fe–29 at.% Al (for sintered Fe 3Al) compacts indicated that the transitory appearance of an intermediate phase, Fe 2Al 5, attributed to this swelling behavior. Further study on the Fe–71.5 at.% Al (for sintered Fe 2Al 5) compacts shows that a large and rapid increase of the specimen’s dimension occurred during a low temperature sintering process, meantime, a sponge-like porous microstructure was obtained. An in situ temperature variation was monitored on these Fe–Al compacts, and a violent and rapidly exothermic heat was found. Compared with the thermal behavior of Ni–Al compacts, it is suggested that many simultaneous fast reactions have occurred inside the Fe–Al mixture during sintering and cause the swelling phenomenon.

Production of glass–ceramic bodies from the bottom ashes of municipal solid waste incinerators

The bottom ashes coming from two different municipal solid waste incinerators were vitrified at 1400 °C. The obtained glass, mixed with other wastes coming from metallurgical and mineral industrial wastes, was used as raw material for the production of glass–ceramic tiles. Two different mixtures were used for the tile production: (a) glass from bottom ashes plus corundum-based waste from an aluminum foundry and (b) glass from bottom ashes plus kaolin-based waste from the kaolin ore extraction process. The tiles were prepared in air by a low-cost, low-temperature pressureless sintering process and were morphologically and mechanically characterized. The sintered materials were found to be good candidates for building applications (tiles, bricks, etc.), i.e. they showed bending strengths up to about 60 MPa and Young modulus up to about 53 GPa.

Sol-gel 법으로 제조된 강유전체 Sr0.9Bi2.1Ta1.8Nb0.2O9박막의 저온결정화 공정

Sol-gel 법으로 제조된 강유전체 Sr_0.9Bi_2.1Ta_1.8Nb_0.2O₉박막의 저온결정화 공정

Syndrome de défaillance multiviscérale compliquant une varicelle en l'absence d'immunodépression

The garnet-type LLZO is one of the most attractive, highly conductive ceramic materials for all-solid-state Li batteries. However, there are so many challenges, such as high temperature sintering for many hours, and air and moisture sensitivity of the materials. In this study, to overcome these obstacles for practical application, we synthesized high conductivity LLZO raw material with Mg, Sr substitution and applied a low temperature sintering process, namely cold sintering, to densify the LLZO-SM-based composites. The LLZO-SM-base composite electrolyte was densified using cold sintering process with DMF as a partially transient liquid phase at 120 °C, and the resulting composite shows a high conductivity of 10−4 S/cm. Moreover, the cold sintered composite electrolyte exhibits high conductivity under a wide range of temperature, as well as good microstructures and grain boundary interfaces. Furthermore, the all-solid-state Li-ion battery with cold sintered composite delivering high capacity was fabricated as a basic demonstration. These promising results demonstrated the feasibility of the cold sintering process for development of solid-state electrolytes and fabrication of all-solid-state Li batteries.

Low-Cost, Large-Area Nanocrystalline TiO2 -Polymer Solar Cells on Flexible Plastics

ABSTRACTThis paper describes our recent research on the development of fully flexible and low-cost dye-sensitized nanocrystalline TiO2 solar cells (DSSC). At EIC Laboratories, we have developed various large-area solid-state versions, which include both ionically, and hole-conducting allpolymer DSSCs made by continuous coating and lamination process. Various critical steps involve ∼10 micron thick nanocrystalline TiO2 film deposition on conducting PET plastics by various methods such as spraying, spin coating, and screen printing, a low temperature sintering (∼150°C) process, and polymer laminated electrolyte have been demonstrated as valuable active components. The photovoltaic (PV) performance presented in this paper show the fabricated solar cells of ∼1.2 cm2 area with reproducible AM1.5 (Air Mass 1.5) efficiencies of 4.7%. A prototype solar cell with a new hole conducting star polymer with AM 1.5 efficiency ∼2.12% has been thoroughly characterized and discussed.

Dielectric properties and phase structure of Pb(Ni1/3Nb2/3)O3-based biphasic ceramics

Pb(Ni1/3Nb2/3)O3-based biphasic ceramics with a low firing temperature(1000°C) and high dielectric constant(3300), which meet the X7R specification of EIA standard, have been prepared by PbTiO3 particle coating technique and mixed sintering method. Dielectric measurements and X-ray diffraction(XRD) analysis show that the ceramics have biphasic structure. The reasons of coexistence of two phases are discussed. PbTiO3 coating layer is able to suppress the formation of solid solution between two Pb(Ni1/3Nb2/3)O3-based phases in the low temperature sintering process.

Non-isovalent alkali metal ?substitution? in YBa2Cu3O7?y granular ceramics

The aim of this paper is to study the influence of non-isovalent “doping” in YBa2Cu3O7−y in particular on its synthesis conditions and on the resistive properties both with and without a magnetic field. We concentrate on the study of possible alkali ions (Na, K, Cs) “substitution” at the barium sites. A low temperature sintering process is used in order to induce a reactive liquid phase. The final chemical composition is discussed as a function of the amount of the liquid phase. No alkali ion is substituted. Carbonate layers are present. However, this (lack of) “substitution” leads to induced vacancies and improved electrical transport properties which are as good as in highly pure materials. For conciseness the case of Na “substitution” only is illustrated. The use of such data in order to probe the microstructure is emphasized.