Зависимость сферы занятости населения от стратегической модели развития экономики

Рассмотрены выделенные современной наукой модели развития экономики: индустриальная, постиндустриальная и информационная (сервисная), а также их основные особенности в контексте формирования занятости и развития экономической активности населения. Обоснованы специфические черты инновационной модели развития страны, которая непосредственно основывается на получении новых научных результатов и их технологическом внедрении в производство

Embedding of bulk piezoelectric structures in low temperature co-fired ceramic

Abstract It has been over a century since the Curie brothers discovered the piezoelectric effect. Since then our knowledge about this phenomena has been constantly growing, accompanied by a vast increase in its applications. Modern piezoelectric devices, especially those meant for use in personal equipment, can often have complicated shapes and electric circuits; therefore, a suitable and cost effective packaging method is needed. The recent introduction of self-constrained Low Temperature Co-fired Ceramic (LTCC) characterized by virtually no planar shrinkage has pushed the limits of this technology a step further. The practical lack of dimension change between “green” state and sintered ceramic has not only improved the design of multilayer smart packages but also allowed the embedding of other bulk materials within the LTCC and their co-firing in one sintering process. This thesis introduces a novel method of seamlessly embedding piezoelectric bulk structures in LTCC by co-firing or bonding with adhesive. Special attention is paid to the multistage lamination and post-firing poling of the piezoelectric ceramics. Examples of several structures from the main areas of piezoelectric applications are presented as proof of successful implementation of the new technique in the existing production environment. The performance of the structures is investigated and compared to structures manufactured using other methods. Integration of bulk piezoelectric structures through co-firing is a new technique with a wide area of applications, suitable for mass production using existing process flow.Tiivistelmä Curien veljekset havaitsivat pietsosähköisen ilmiön jo yli sata vuotta sitten. Ilmiöön liittyvä tutkimustieto ja erityisesti siihen perustuvien sovellusten määrä on nykyisin valtava. Uusissa pietsosähköisissä komponenteissa ja varsinkin niissä, jotka on tarkoitettu henkilökohtaisissa laitteissa käytettäviksi, muodot samoinkuin elektroniikapiirit voivat olla monimutkaisia. Siksi tarvitaan tarkoituksenmukaista ja hinnaltaan edullista laitteen pakkausmenetelmää. Hiljattain kehitetyt itseohjautuvat matalan lämpötilan yhteissintattavat keraamit (LTCC), joiden planaarinen kutistuma on lähes olematon, ovat lisänneet LTCC-teknologian sovellusmahdollisuuksia. Muotoon valmistetun sintraamattoman ja lopullisen sintratun keraamin dimensioiden yhtäsuuruus ei ole ainoastaan parantanut älykkäiden monikerrospakkausten suunnittelua, vaan mahdollistanut myös erilaisten materiaalien ja komponenttien upottamisen LTCC-rakenteisiin ja niiden yhteissintrauksen. Väitöstyössä esitetään uusi menetelmä pietsosähköisten bulkrakenteiden upottamiseksi saumattomasti LTCC-rakenteisiin yhteissintrauksella tai liimaliitoksella. Erityistä huomiota on kiinnitetty monivaiheiseen laminointiin ja sintrauksen jälkeiseen pietsosähköisten keraamien polarisointiin. Työssä on esitetty esimerkkejä useista rakenteista pietsosähköisten sovellusten pääalueilta osoituksena uuden tekniikan onnistuneesta käyttöönottamisesta nykyisessä valmistusympäristössä. Tutkittujen uusien rakenteiden ja muilla menetelmillä valmistettujen rakenteiden ominaisuuksia on verrattu keskenään. Pietsosähköisten bulkrakenteiden integroiminen yhteissintrauksella on uusi tekniikka, joka mahdollistaa lukuisia sovelluksia ja soveltuu massatuotantoon olemassa olevilla prosseintilaitteistoilla

Performance of LTCC embedded SiC gas sensors

A novel approach to encapsulation/packaging of SiC field effect transistor gas sensors for high temperature applications, such as exhaust and fuel gas emissions monitoring, based on direct co-firing of sensor devices and Low-Temperature Co-fired Ceramics (LTCC) has been investigated. Structural (SEM, EDX, XPS), electrical (I/V, C/V) as well as gas sensing characterization of packaged devices has shown that the “one-step” packaging process forms a hermetic package with retained transducer functionality and gas sensing characteristics without the need for any separate die attachment, (wire) bonding, and/or sealing of the package. Long-term stability testing at elevated temperatures of packaged devices has also shown promising results

Performance of LTCC embedded SiC gas sensors

A novel approach to encapsulation/packaging of SiC field effect transistor gas sensors for high temperature applications, such as exhaust and fuel gas emissions monitoring, based on direct co-firing of sensor devices and Low-Temperature Co-fired Ceramics (LTCC) has been investigated. Structural (SEM, EDX, XPS), electrical (I/V, C/V) as well as gas sensing characterization of packaged devices has shown that the “one-step” packaging process forms a hermetic package with retained transducer functionality and gas sensing characteristics without the need for any separate die attachment, (wire) bonding, and/or sealing of the package. Long-term stability testing at elevated temperatures of packaged devices has also shown promising results

Multilayer functional tapes cofired at 450 °C:beyond HTCC and LTCC technologies

Abstract This paper reports the first ultralow sintering temperature (450 °C) cofired multifunctional ceramic substrate based on a commercial lead zirconium titanate (PZ29)–glass composite, which is fabricated by tape casting, isostatic lamination, and sintering. This substrate was prepared from a novel tape casting slurry composition suitable for cofiring at low temperatures with commercial Ag electrodes at 450 °C. The green cast tape and sintered substrate showed a surface roughness of 146 and 355 nm, respectively, suitable for device-level fabrication by postprocessing. Additionally, the ferroelectric and piezoelectric studies disclosed low remnant polarization due to the dielectric glass matrix with average values of piezoelectric coefficient (+d33) and voltage coefficient (+g33) of 17 pC/N and 30 mV/N, respectively. The dielectric permittivity and loss value of the sintered substrates were 57.8 and 0.05 respectively, at 2.4 GHz. The variation of relative permittivity on temperature dependence in the range of −40 to 80 °C was about 23%, while the average linear coefficient of thermal expansion was 6.9 ppm/°C in the measured temperature range of 100–300 °C. Moreover, the shelf life of the tape over 28 months was studied through measurement of the stability of the dielectric properties over time. The obtained results open up a new strategy for the fabrication of next-generation low-cost functional ceramic devices prepared at an ultralow temperature in comparison to the high-temperature cofired ceramic and low-temperature cofired ceramic technologies

LTCC, new packaging approach for toxic gas and particle detection

Packaging of chemical sensors is still an area, which is not much explored. Low temperature co-fired ceramic, LTCC, packaging offers large advantages in terms of 3D design, integration of advanced functionality and fast processing. SiC based FET gas sensors are possible to integrate directly in the LTCC co-firing process at 850 °C, whereby both high temperature and other advanced applications like ultra-low detection of toxic gases are greatly improved. The LTCC packaging is also used for development of particle detectors as well as packaging for an electrical method to detect toxic effect on cells by particles

3D printed dielectric ceramic without a sintering stage

Abstract This paper presents for the first time the fabrication of dielectric ceramic parts by 3D printing without sintering. The printable paste was prepared by mixing a carefully selected amount of water-soluble Li₂MoO₄ powder with water. A viscous mixture of solid ceramic particles and saturated aqueous phase was formed with a solid content of 60.0 vol.%. Printing of the sample discs was conducted with material extrusion using a low-cost syringe-style 3D printer. The consolidation and densification of the printed parts occurred during both printing and drying of the paste due to extrusion pressure, capillary forces, and recrystallization of the dissolved Li₂MoO₄. Complete drying of the paste was ensured by heating at 120 °C. The microstructure showed no delamination of the printed layers. Relatively high densities and good dielectric properties were obtained, especially when considering that no sintering and only pressure from the extrusion was employed. This approach is expected to be feasible for similar ceramics and ceramic composites

Electromechanical properties of PZT/P(VDF-TrFE) composite ink printed on a flexible organic substrate

Abstract The fabrication and electromechanical properties of composite inks consisting of 30–70 vol.% of piezoceramic PZT powder and piezoelectric co-polymer P(VDF-TrFE) are presented. Samples were stencil-printed on a commercial PET film and printable silver ink was used for the electrodes thus allowing a maximum process temperature of 130 °C. The relative permittivity at 1 kHz varied between 33 and 69 depending on poling and composite composition. The highest remanent polarization, up to 4.8 μC/cm², with 34 MV/m electric field and piezoelectric coefficient d₃₁ up to 17 pm/V, was obtained with a 50 vol.% PZT loading level. The mechanical and electrical results indicate that the developed composite ink enables fully printable and flexible sensor applications with an increased level of integration