3^rd PCNS Passive Components Networking Symposium​

Abstract:

Having supplying inductive electronic components to worldwide Space businesses in accordance with MIL standards (type FT) for 25 years, Flux was granted ESA QML status based on Technology Flow Qualification (TFQ) in March 2020. In the cause of the TFQ process, Flux authored the applicable EESCC Detail Specification ESCC3201/013 “Customized Magnetics (inductors, transformers) based on type FT” in cooperation with the ESCC. As the TFQ is rare and unknown to many, only granted to five companies within different component types, Flux will present the outline of the TFQ and the resulting processes related to the design and manufacturing of inductive electronic components. The requirements of MIL-STD-981 (design), MIL-PRF-27 (performance) and MIL-STD-202 (test) are fairly well known and formed the baseline of Flux design and manufacturing for 25 years. The presentation will focus on the augmented responsibilities of being ESA QML by TFQ and will shed light on routines as: 1) ESCC Domain and its maintenance via periodic ESCC Qualification test including modifications from ESCC3201 in ESCC3201/013 2) Design feasibility and ESCC documentation including the design envelope documentation (PID, DML, DPL) 3) Function of the ESCC Technology Review Board approving each design proposed for ESCC Qualified Part status 3) The process flow of creating a new ESCC Qualified Part or updating an existing MIL-STD Part to ESCC Qualified 4) ESCC3201/013 Screening methods and responsibilities undertaken by the supplier, why ESCC Qualified Parts are deemed “Use as is” when delivered Finally, the presentation will sum up the buyer’s advantages of procuring ESCC Qualified Parts for various electronic applications.

Co-Authors:
V.Sedlakova, P.Tofel; Brno University of Technology; Czech Republic

Abstract:

Increase of capacitors’ energy density is of prime interest in number of today’s applications. High energy density, high voltage capacitors are especially needed in fast-growing segments such as automotive, renewable energy generation and transmission, medical etc.

Film power capacitors are dominating the high voltage segment; however, this technology is limited with lifetime at high temperatures and relatively low energy density level. High capacitance, high energy density MLCC capacitors based on class II dielectric materials offer small, compact size, high reliability, and high temperature range, however it shows significant capacitance (and energy) deterioration with applied voltage that reduces its real energy storage capability as its remarkable disadvantage.

This paper presents a study on suitability of doped BaTiO3 (BT) based, ferroelectric ceramic materials BCST and BT-11BS with low Curie temperatures as high energy density capacitor dielectrics. Aim of the research was to evaluate key features of these materials and optimize its process parameters to assess potential benefits as a high energy density capacitor dielectric.

Electrical parameters such as permittivity, electrical field strength, temperature dependence and capacitance with voltage dependency were evaluated on lab manufactured samples and benchmarked to the reference-made pure BT material samples.

Key finding on the low Curie temperature materials is that permittivity/capacitance with BIAS voltage does not decrease so rapidly at temperatures above the Curie temperature. This phenomenon increases a total energy storage density across operating voltage and temperature range as demonstrated on BT-11BS material with Curie temperature as low as 37°C. This, so far possibly overlooked behaviour by capacitor manufacturers, could bring a new direction in development of higher energy density and more stable ceramic capacitors.

Both BCST and BT-11BS evaluated low Curie temperature materials showed higher energy density compare to the pure BT reference material, nevertheless BCST’s high dielectric losses and low efficiency degrade its dielectric features, thus it may not be a suitable candidate for capacitor dielectric.   

The highest energy density on BT-11BS after process optimisation achieved up to 10x higher ED than BT reference material and improved permittivity stability with applied voltage and temperature.

Co-authors:
Jiri Navratil, Michaela Radouchova, Daniela Moravcova, Frantisek Steiner, and Ales Hamacek; University of West Bohemia, Faculty of Electrical Engineering, Department of Materials and Technology; Czech Republic

Abstract:

At present, the popularity of wearable smart textiles is growing. These textiles are used in many novelty applications such as safety elements, health care or well-being products, sport garments, etc. One of the possible material used for these textiles are electrically conductive ribbons. These ribbons are flexible, stretchable and it is possible to make electrically conductive contact of SMD component onto these ribbons, which was proved in our previous experiments.

These contacts can be done by gluing or by soldering. The question is the reliability of each connection method in various environments where the product is expected to be used. The wearable textiles have to withstand various conditions affected by many factors. One of them is sweat which might be a significant factor e.g. for smart textile sports garments.

The reliability of joints between SMD chip resistors glued or soldered onto the textile ribbons during the accelerated ageing by synthetic sweat has been investigated and will be described in the full paper. In our research, the conductive textile ribbons with silver coated copper conductive wires were used.

Ten SMD chip resistors with 0 ohm resistance with case size 1206 were used for each tested sample. The two different methods for connection of resistor to the ribbon were used. First method was using a non-conductive adhesive to make a direct conductive contact between component pads and conductive wires in ribbon. The electrical connection is made by direct contact of pads and wires. This contact is mechanically fixed by the adhesive. The second method was using low temperature soldering by tin-bismuth solder paste. The joints with connected resistors were finally encapsulated by adhesive to improve the protection against outer environment for both methods.

The electrical resistance of joints was measured by four point probe method with measurement device Keithley 2700. The two different types of synthetic sweat (acidic and alkaline solution) were prepared for the test according to the standard ISO 105-E04. The acidic solution sweat was used for one half of samples and alkaline solution sweat was used for second half of samples.

The samples were submitted to the 25 cycles. Each cycle consisted of 30 minutes immersion of samples to the sweat, drying of samples in dryer, measuring of joints’ electrical resistance, immersion of samples to the demineralized water for 30 minutes, drying of samples in dryer, and measuring of joints’ electrical resistance. After first 15 cycles the immersion time in sweat was extended to the 24 hours and after next 5 cycles the immersion time in sweat was extended to the 168 hours (1 week). The results of both joint types were statistically analysed and compared. Also the metallographic cross sections of samples were realized.

The changes of joints, resistors’ pads and conductive wires were observed. These results are going to be published in the full paper.

Co-authors:
Jiri Stulik; University of West Bohemia; Czech Republic

Abstract:

Carbon is one of the basic elements that has been used in electronics for a long time. Carbon occurs in various forms (allotropes) such as graphite, diamond, carbon nanotubes or graphene. In particular, carbon nanotubes and graphene are increasingly used in the field of electronic components and sensors. Carbon nanotubes can be chemically modified and thus change their chemical as well as electrical properties.

Modification is when CNTs bind other organic or inorganic substances to themselves, thereby changing their physical and chemical properties. These materials can be used to implement basic interconnection structures and create more complex electronic components. They are used in the field of passive electronic components and in the construction of organic FET transistors to improve their electrical parameters. Modified carbon nanotubes are preferably used as sensitive layers in environmental sensors.

With the help of these materials, it is possible to realize planar sensors, where the appropriate type of modification gives the sensitivity to a certain analyte. The advantage of these materials is that printing techniques can be used for creating functional electronic structures and thus realized flexible and planar electronic elements or entire systems.

Materials based on carbon nanotubes are organic materials, and thus, when applied to environmentally degradable substrates, they enable the realization of biodegradable electronic elements and systems. The article will present various electronic components and sensors based on modified carbon nanotubes and graphene, including their measured basic electrical parameters and properties.