Purpose: The purpose of this study is to design and fabricate a simple passive sensor circuitry embedded into a printed circuit board (PCB) and then to examine its properties. Design/methodology/approach: A passive sensor transponder integrated circuit (IC) working in the high frequency (HF) 13.56 MHz frequency band was selected for this study. A loop antenna was designed to make the reported sensor circuitry readable. Next, the sensor circuitry was fabricated and embedded into a PCB with the proposed technologies. Finally, properties of the embedded structures were examined as well-functional parameters of the sensor circuitries. Findings: The described investigation results confirmed that the proposed technologies using an epoxy resin or standard materials used for PCB’s production allowed to successfully produce sensors embedded into PCBs. This technology did not have a negative significant impact either on quality of solder joints of the assembled transponder IC or on functional properties of the embedded sensor. Apart from the identification data, the reported sensor can provide information about a selected property of its environment, e.g. temperature when its internal temperature sensitive element is used or other factors with the use of external sensitive elements, such as humidity. Research limitations/implications: It is planned to carry on the reported investigations to examine other types of sensor circuitries capable of indicating e.g. humidity level and to evaluate influence of the proposed technology on their functional properties. Practical implications: The reported sensor circuitries can be successfully used in electronic industry in internet of things systems not only to identify monitored electronic devices, but also to control selected parameters of external environment. This creates opportunity to detect device malfunction by detecting local temperature growth or to analyze its environment, which might allow to predict failure of controlled products using radio waves. This advantage seems to be extremely beneficial for applications, such as space, aviation or military, in which embedded sensor systems may lead to enhancing reliability of electronic devices by reacting on occurred failures in a more efficient way. Originality/value: This study demonstrates valuable information for engineers conducting research on sensor components embedded into PCBs. The reported technologies are quite simple and cost-effective because of the use of standard materials known for PCB’s production or an epoxy resin which could be treated as an additional encapsulant material enhancing mechanical properties of the embedded sensor transponder IC.

The purpose of the experiment was to indicate which element of the production process of flexible printed circuit boards is optimal in terms of the reliability of final products. According to the Taguchi method, in the experiment, five factors with two levels each were chosen for the subsequent analysis. These included the number of conductive layers, the thickness of the laminate layer, the type of the laminate, the diameter of the plated holes, and the current density in the galvanic bath. The reliability of the PCBs in the produced variations was verified using the Interconnect Stress Test environmental test. The qualitatively best variant of the board construction was indicated using the signal-to-noise ratio and the analysis of variance method for each factor. The factors determined to be the most important in terms of reliability were the number of conductive layers and the current density in the galvanic bath. The optimal variant of the board construction was two conductive layers on a polyimide laminate, where the laminate layer was 100 μm thick, the hole diameter was equal to 0.4 mm, and current density was 2 A/dm² in the galvanic bath. Therefore, the plated experiment indicated the factors needed to obtain a high-quality product with a low failure rate.

The technique of embedding components inside printed circuit boards (PCBs) is described, using different filling masses. To investigate the possibility of placing the components inside the printed circuit board, a residual circuit breaker with an overload protection (RCBO) system was adapted. Four types of fillings (two epoxy and two silicone) were used in the tests, which were carried out showing the full functionality of the systems embedded in the PCB, regardless of the applied sealing compound. A certain disadvantage was the shrinkage of the applied masses, which was visible in some cases in the occurrence of gaps in the flooding spaces. However, it should be emphasized that the tests were preliminary and that the adjustment of the filling shrinkage will be optimized in subsequent tests.

The purpose of the experiment was to indicate which element of the production process of flexible Printed Circuit Board is optimum in terms of the reliability of final products. According to the Taguchi method in the experiment five factors, two levels each, were chosen for the subsequent analysis. These include: the number of conductive layers, the thickness of the laminate layer, type of the laminate, the diameter of the plated holes, the current density in the galvanic bath. The reliability of the PCBs in produced variations was verified using the Interconnect Stress Test environmental test. The qualitatively best variant of the board construction was indicated using the signal-to-noise ratio and analysis of variance method for each factor. The factors that turned out to be the most important in terms of reliability are the number of conductive layers and the current density in the galvanic bath. The optimal variant of the board construction is two conductive layers, on a polyimide laminate, where laminate layer is 100 μm thick, hole diameter equal to 0.4 mm and current density of 2 A/dm2 in the galvanic bath. Therefore the plated experiment indicated factors needed to obtain a high-quality product with a low failure rate.