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Embedded components are one of the current trends in electronics, allowing to produce more compact devices with increased functionality. Such components can be applied, among others, in fabrication devices used in the Internet‐of‐Things technology or in special industries. Therefore, their reliability plays a key role due to safety requirements and high deployment costs. Herein, the thermal reliability of a system of sensors embedded into a printed circuit board (PCB) is examined. The samples produced are exposed to temperature cycling, −40 °C/+105 °C, or high temperature/high humidity, 85 °C/85% relative humidity (RH). The quality of solder joints is evaluated on the basis of X‐ray inspection and cross sections before and after the exposure mentioned earlier. The tests show no damage to the solder joints of the samples subjected to reliability testing in high‐temperature/high‐humidity conditions, irrespective of the solder alloy used. Cracks appear after 500 cycles, −40 °C/+105 °C, in samples soldered with Sn99Cu1 and after 1000 temperature cycles in both Sn99Cu1 and LFM‐48S (SnAg3.0Cu0.5) solders. The presented results are used for efficient embedding of electronic components into PCBs. Consequently, more space is gained for other components and the size of the electronic products is minimized. [ABSTRACT FROM AUTHOR]

Circular Economy (CE) is one of the approaches which are intensively developed and tested in different areas of industry and services. The aim of this solution is to use many kinds of resources in a closed flow and to achieve as a small amount of waste as it is possible. One of the potential areas of using CE is Radio Frequency Identification (RFID). In RFID systems tags are utilized in various forms. This paper addresses investigation of a recycling process of RFID tags. Different attachment methods of these tags were tested and then, a recycling procedure was prepared based on the obtained results in which adhesives are recommended to be used as an attaching material between a tag and an identified object. The mentioned procedure was evaluated with using paper-face RFID tags. It was confirmed applicability of the proposed solution. Moreover, the conducted research revealed that an adhesion force of the adhesive layers in the prepared RFID tags decreased in the most extent during the first recycling cycle. It was found that in order to preserve a high adhesion force of these layers it is suggested to place the tags on a clean surface. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this paper is to investigate screen-printed high-frequency (HF) antennas for radio frequency identification (RFID) on-metal transponders in which a magnetic sheet was used as a substrate material. Design/methodology/approach – A transponder antenna was designed in the form of square coil using a high-frequency electromagnetic software. Then, the antenna was fabricated with screen printing technique on two different magnetic sheets (RFN4 and RFN7) and on polyethylene naphthalate (PEN) foil for comparison. Its printing was carried out with polymer pastes based on silver flakes (PM-406 and SF). Thickness, track width and spacing were examined for the antennas using digital microscope and contact profilometer. Resistance and inductance were also measured, and resonant frequency, quality factor and target values of capacitance to achieve resonant frequency of the tested antenna at 13.56 MHz were calculated. Finally, RFID chips were mounted to the prepared antennas using an isotropic conductive adhesive, and a maximum read distance was measured with a reader installed in a smartphone. Findings – It was found that an antenna thickness on the magnetic sheets used was higher than on PEN foil. At the same time, surface roughness of the fabricated antennas on these sheets was revealed to be higher as well. Inductance of the measured antennas exhibited good conformity with the antenna design, but higher divergence was noticed in the measured resistance. Its lowest value was achieved when the antenna was printed with the paste PM-406 on PEN foil and the highest one when it was fabricated with the paste SF on the same substrate. This suggests that high attention needs to be paid to a polymer paste selected for antenna printing. The performed tests showed that the magnetic sheet RFN4 seems to be better substrate for on-metal transponders compared to RFN7 due to lower resistance and higher quality factor of the prepared antennas. Research limitations/implications – Further investigations are required to examine mechanical and thermal durability of the HF antennas printed on the magnetic sheets. Practical implications – The investigated HF antennas fabricated on magnetic sheets can find application in near field communication (NFC) transponders designed to be placed on metallic surfaces, e.g. on frames of advertising screens. Originality/value – Influence of used magnetic sheets and polymer pastes on geometry and electrical properties of HF antennas for RFID on-metal transponders was investigated. The presented investigations can be interesting for NFC/RFID designers who are involved in designing systems suitable for metallic surfaces. [ABSTRACT FROM AUTHOR]

Purpose – The purpose of this paper was to determine the influence of thermal aging on the stability of organic light-emitting diode (OLED) glass samples made in ambient condition. Design/methodology/approach – The samples with yellow emitting layer (named as ADS5) and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) hole transport layer were examined. Some of the devices were ultraviolet-curable epoxy encapsulation directly after performance. All samples were thermally annealed at 70°C for 1, 2, 3 and 4 hours. The characteristics current–voltage for fresh and aging samples in the range of voltage from 0-15 V were made. The temperature of OLEDs samples in real-time with a thermographic camera was measured too. Additionally, scanning electron microscope image of surface Al cathode immediately after OLED performance and after annealing tests was made. Findings – The authors stated, that irrespective of the type, the samples were undergoing the degradation. The decrease in value of the current density was registered. That were about 44 per cent and about 24 per cent after thermally annealing the samples with and without encapsulation, respectively (at tension 13 V). Additionally, there were observed massive delamination of the metal cathode. Originality/value – Influence of thermal annealing and encapsulation on the dynamic characteristics of the OLED devices fabricated in ambient condition was analyzed. There are not many papers in the literature describing examinations of OLED samples which were made in environmental conditions. [ABSTRACT FROM AUTHOR]

In this work, a study of the surface properties of treated indium tin oxide (ITO) substrates is reported. We used three different cleaning treatments among others: washing in an ultrasonic bath of acetone and ethyl alcohol or isopropyl alcohol in room temperature as well as dipping into solution (prepared from NHOH (25 %), HO (30 %) and distilled water) at 60 °C. The relation between ITO morphology and surface properties has been studied by contact angle, and surface energy measurements as well as the surface roughness of ITO samples evaluation by atomic force microscopy (AFM). Experimental results show that the ITO surface properties are closely related to the treatment methods. The ultrasonic degreasing in acetone and ethyl alcohol yields the highest surface energy (38 .5 mJ /m), brings about the maximum reduction in contact angles and causes the smallest increasing the surface roughness of ITO substrates. [ABSTRACT FROM AUTHOR]