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1 – 10 of 141Jakub Somer, Michal Štekovič, František Urban, Josef Šandera and Ivan Szendiuch
The purpose of this paper is to focus on a description of reliable bonding technique of zero-shrink low-temperature co-fired ceramic (LTCC) and alumina ceramics. LTCC is widely…
Abstract
Purpose
The purpose of this paper is to focus on a description of reliable bonding technique of zero-shrink low-temperature co-fired ceramic (LTCC) and alumina ceramics. LTCC is widely used for manufacturing electrical systems in 3D configuration. LTCC substrates were so far bonded with alumina ceramics using additional adhesive layers with subsequent firing or curing cycle. With the advent of the zero-shrink LTCC substrates, it is now possible to bond unfired substrates with other fired substrates, for example fired LTCC or alumina substrates. Alumina substrate in combination with LTCC brings advantages of good thermal conductivity for usage in heating elements or packaging.
Design/methodology/approach
The test structure contains a thick-film pattern for verification of the compatibility of the bonding process. We have used two methods for bonding the substrates: cold chemical lamination (CCL) and thermo compression method, using a dielectric thick-film paste as the adhesive. Optical microscopy, scanning electron microscopy and electric testing of the screen-printed patterns were used for verification of the bonding quality.
Findings
The thermo-compression method gave poor results in comparison with the CCL method. The best quality of lamination was achieved at room temperature combined with low pressure for both types of bonding materials. In addition, a possibility of using this bonding method for sensor fabrication was investigated. The ceramic pressure sensor samples with a cavity were created.
Originality/value
The possibility of bonding two different ceramic materials was investigated. A new approach to ceramic bonding showed promising results with possible use in sensors.
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Eszter Horvath, Gabor Henap and Gabor Harsanyi
In microfluidic channel fabrication in low temperature co‐fired ceramics (LTCC), one of the biggest challenges is the elimination of channel deformation during lamination. The…
Abstract
Purpose
In microfluidic channel fabrication in low temperature co‐fired ceramics (LTCC), one of the biggest challenges is the elimination of channel deformation during lamination. The purpose of this paper is to describe the expected deformation of the substrate and the sacrificial layer (starch powder and 3D printed UV polymerized material) during the lamination process of microfluidic structure fabrication.
Design/methodology/approach
Uniaxial compression and Jenike shear test were used to obtain the mechanical parameters of starch sacrificial volume material (SVM). To determine the stress‐strain characteristics of LTCC a uniaxial compression experiment was conducted. The shape of the laminated LTCC containing embedded channel was modeled by finite element method using the mechanical parameters obtained by the measurements.
Findings
It was found that the choice of SVM plays an important role in channel deformation. A design rule is given considering the channel width and the choice of SVM based on the simulation results.
Originality/value
Until now the lamination step of LTCC technology was only optimized in an empirical way.
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Beata Synkiewicz, Dorota Szwagierczak and Jan Kulawik
The paper aims to report on fabrication procedure and present microstructure and dielectric behavior of multilayer porous low-temperature cofired ceramic (LTCC) structures based…
Abstract
Purpose
The paper aims to report on fabrication procedure and present microstructure and dielectric behavior of multilayer porous low-temperature cofired ceramic (LTCC) structures based on glass-cordierite and glass-alumina.
Design/methodology/approach
The LTCC structures were created as multi-layered composites with dense external layers and inner layers with intentionally introduced porosity. Two preparation methods were applied – subsequent casting of both kinds of slurries and conventional isostatic lamination of dried green tapes arranged in the designed order. Optical microscope observations were carried out to analyze the microstructure of green and fired multilayer structures and pore concentration. To evaluate the adhesion strength of the composite layers, pull test was performed. Dielectric behavior of the composites was studied in the frequency range 50 kHz-2 MHz.
Findings
The fabricated porous LTCC structures showed dielectric constant of 3-5.6. The lowest dielectric constant was attained for glass-cordierite composite made by the conventional tape casting/lamination/firing method from slurry with 50 per cent graphite content. The samples prepared using multiple casting were of worse quality than those fabricated in conventional process, contained irregular porosity, showed tendency for deformation and delamination and exhibited a higher dielectric constant.
Originality/value
Search for new low dielectric constant materials applicable in LTCC technology and new methods of their fabrication is an important task for development of modern microwave circuits.
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– The paper aims to present the influence of the co-firing process conditions of low temperature co-fired ceramics (LTCC) on the deformation of thin LTCC membranes.
Abstract
Purpose
The paper aims to present the influence of the co-firing process conditions of low temperature co-fired ceramics (LTCC) on the deformation of thin LTCC membranes.
Design/methodology/approach
The statistical design of the experiment methodology was used in the frame of these investigations to reduce the time and costs of the experiments and to ensure easier interpretation of the obtained results. Moreover, this conception permits the rough estimation of the membrane deflection fired at optimal process conditions.
Findings
The applied design of the experiment methodology allowed the researchers to find the optimal co-firing process conditions and to estimate the membrane deflection at the optimal process conditions. The estimation fits well with the results of real measurement that was conducted to confirm the estimation precision.
Research limitations/implications
The experiment was conducted for only one type of LTCC, DP951. The precision of the design of the experiment optimization and estimation of the response at optimal conditions depend on the described object. Therefore, the findings of this paper do not have to be generally true for other LTCC tapes, and if other LTCC tapes deformation should be investigated, then similar analysis shall be conducted for them.
Practical implications
The deformation of LTCC membranes affects the sensitivity and repeatability of LTCC acceleration and pressure sensors. Hence, the decrease of membrane deflection increases the usability of LTCC in such applications.
Originality/value
This paper presents simple optimization of co-firing process conditions of LTCC devices using statistical design of the experiment.
Arkadiusz Dabrowski, Karl Elkjaer, Louise Borregaard, Tomasz Zawada and Leszek Golonka
The purpose of this paper is to develop the device made of low temperature co-fired ceramics (LTCC) and lead zirconate titanate (PZT) by co-firing both materials. In the paper…
Abstract
Purpose
The purpose of this paper is to develop the device made of low temperature co-fired ceramics (LTCC) and lead zirconate titanate (PZT) by co-firing both materials. In the paper, the technology and properties of a miniature uniaxial ceramic accelerometer are presented.
Design/methodology/approach
Finite element method (FEM) is applied to predict properties of the sensor vs main dimensions of the sensor. The LTCC process is applied during manufacturing of the device. All the advantages of the technology are taken into account during designing three-dimensional structure of the sensor. The sensitivity and resonant frequency of the accelerometer are measured. Real material parameters of PZT are estimated according to measurement results and FEM simulations.
Findings
The ceramic sensor integrated with SMD package with outer dimensions of 5 × 5 × 5 mm3 is manufactured. The accelerometer exhibits sensitivity of 0.75 pC/g measured at 100 Hz. The resonant frequency is equal to about 2 kHz. Useful frequency range is limited by 3 dB sensitivity change at about 1 kHz.
Research limitations/implications
Sensitivity of the device is limited by interaction between LTCC and PZT materials during co-firing process. The estimated d parameters are ten times worse comparing to bulk Pz27 material. Further research on materials compatibility should be carried out.
Practical implications
The sensor can be easily integrated into various devices made of standard electronic printed circuit boards (PCBs). Applied method of direct integration of piezoelectric transducers with LTCC material enables manufacturing of complex ceramic systems with built-in accelerometer in the substrate.
Originality/value
The accelerometer is a sensor and a package simultaneously. The miniature ceramic device is compatible with surface mounting technology; hence, it can be used directly on PCBs for vibration monitoring inside electronic devices and systems.
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K. Masaoka, Y. Tanaka and H. Kobayashi
Fine line circuitry has become much more common in printed wiring board manufacturing during the past decade. Manufacturers are currently producing 4 or 5 conductor lines between…
Abstract
Fine line circuitry has become much more common in printed wiring board manufacturing during the past decade. Manufacturers are currently producing 4 or 5 conductor lines between circuits. Line definition is 100 μm line and space and high yields in manufacturing must be achieved when small land through‐holes with small annular rings are now being fabricated to meet the requirements of high density circuits by plating, hole filling and so forth. This company has found that a newly developed combination of vacuum lamination and primary imaging dry film which is suitable for small annular ring formation will offer advantages not available with current technologies. It has advantages such as more than 60 μm encapsulation of resist into through‐holes, no ten breakage when incorrect registration of phototool with 130 μm occurs and availability of 2.5 m/min lamination speed. The Hi‐VS System will make it possible to obtain higher yield in very fine line fabrication.
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THE object of this article is to deal with the present day use of urea‐formaldehyde resin glues in the aircraft industry. This type of glue is used in two spheres of the industry…
Abstract
THE object of this article is to deal with the present day use of urea‐formaldehyde resin glues in the aircraft industry. This type of glue is used in two spheres of the industry. (1) In the manufacture of plywood of aircraft quality, and (2) in the manufacture of wooden aircraft structures.
The phosphate treatment of metals has been in industrial use for over 50 years and is the most widely used method of treating light‐gauge steel as a preparation for painting; in…
Abstract
The phosphate treatment of metals has been in industrial use for over 50 years and is the most widely used method of treating light‐gauge steel as a preparation for painting; in addition, during the last 20 years, its use as an aid in the cold forming of steel in such operations as tube and wire drawing has been established. As a result of these trends, phosphating is now a very significant part of the whole metal finishing industry. This review includes advancements in operation, composition and use.
Elina Ilén, Farid Elsehrawy, Elina Palovuori and Janne Halme
Solar cells could make textile-based wearable systems energy independent without the need for battery replacement or recharging; however, their laundry resistance, which is…
Abstract
Purpose
Solar cells could make textile-based wearable systems energy independent without the need for battery replacement or recharging; however, their laundry resistance, which is prerequisite for the product acceptance of e-textiles, has been rarely examined. This paper aims to report a systematic study of the laundry durability of solar cells embedded in textiles.
Design/methodology/approach
This research included small commercial monocrystalline silicon solar cells which were encapsulated with functional synthetic textile materials using an industrially relevant textile lamination process and found them to reliably endure laundry washing (ISO 6330:2012). The energy harvesting capability of eight textile laminated solar cells was measured after 10–50 cycles of laundry at 40 °C and compared with light transmittance spectroscopy and visual inspection.
Findings
Five of the eight textile solar cell samples fully maintained their efficiency over the 50 laundry cycles, whereas the other three showed a 20%–27% decrease. The cells did not cause any visual damage to the fabric. The result indicates that the textile encapsulated solar cell module provides sufficient protection for the solar cells against water, washing agents and mechanical stress to endure repetitive domestic laundry.
Research limitations/implications
This study used rigid monocrystalline silicon solar cells. Flexible amorphous silicon cells were excluded because of low durability in preliminary tests. Other types of solar cells were not tested.
Originality/value
A review of literature reveals the tendency of researchers to avoid standardized textile washing resistance testing. This study removes the most critical obstacle of textile integrated solar energy harvesting, the washing resistance.
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Mukesh Kumar Singh and Annika Singh
Protection of medical personnel against pathogenic viruses is a challenging task for the world scientific community. The purpose of this paper is to collect, analyze, critique…
Abstract
Purpose
Protection of medical personnel against pathogenic viruses is a challenging task for the world scientific community. The purpose of this paper is to collect, analyze, critique, rearrange and present the scattered information scientifically to form a base for product development for viral protection.
Design/methodology/approach
A huge range of recently available information has been collected, studied and arranged judiciously.
Findings
After an exhaustive study of this topic, it is possible to present all information in a manner that will be helpful to start product development activity on both sides of the Atlantic. Initially, various coated textiles with zero breathability were used to cover doctors, nurses and staff but thereafter microporous coatings replaced the poreless surface coatings. However, the pore size distribution in microporous films and coatings could not be controlled precisely and manufacturers could not claim the surface offered foolproof protection against viruses. Monolithic films are able to claim guaranteed protection against virus penetration, with sufficient breathability. Monolithic film technology has prime importance in protective clothing that has to be discussed judiciously. Permeability of block copolymers based monolithic films is an important feature for barrier materials, high performance impermeable breathable clothing and membrane separation processes.
Originality/value
This is a first paper in the field of viral barrier fabrics which will remain helpful to the scientific community to start further research work and product development.
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