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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]

Purpose The purpose of this paper is to investigate the behavior of embedded passives under changing temperature conditions. Influence of different temperature changes on the basic properties of embedded passives was analyzed. The main reason for these investigations was to determine functionality of passives for space application.Design/methodology/approach The investigations were based on the thin-film resistors made of Ni-P alloy, thick-film resistors made of carbon or carbon-silver inks, embedded capacitors made of FaradFlex materials and embedded inductor made in various configurations. Prepared samples were examined under the influence of a constant elevated temperature (100, 130 or 160°C) in a long period of time (minimum of 30 h), thermal cycles (from −40 to +85°C) or thermal shocks (from −40 to +105°C or from −40 to +125°C).Findings The achieved results revealed that resistance drift became bigger when the samples were treated at a higher constant temperature. At the same time, no significant difference in change in electrical properties for 50 and 100 Ω resistors was noticed. For all the tests, resistance change was below 2 per cent regardless of a value of the tested resistors. Conducted thermal shock studies indicate that thin-film resistors, coils and some thick-film resistors are characterized by minor variations in basic parameters. Some of the inks may show considerable resistance variations with temperature changes. Significant changes were also exhibited by embedded capacitors.Originality/value The knowledge about the behavior of the operating parameters of embedded components considering environmental conditions allow for development of more complex systems with integrated printed circuit boards. [ABSTRACT FROM AUTHOR]

Aim of the research was to examine the effectiveness of various methods to remove moisture from printed circuit boards (PCBs) depending on PCB's type and process parameters. The presented results are part of ongoing research on the absorption and desorption of moisture. The additional aim is to find new solutions to increase the reliability of electronics. The results are useful for whole EMS market because they facilitate to select the most appropriate method for their products. The initial conditions and parameters of the process are selected to reduce the risk associated with high temperature annealing while preventing damage caused by moisture during soldering. The FLEX, RIGID-FLEX and SEMI-FLEX PCBs were fabricated. All PCBs were humidified and exposed to drying conditions in which elevated temperature, reduced humidity or reduced pressure were utilized. The parameters were set by taking into account material characteristics, process time and operation cost. Mass of the samples was measured before and after annealing so as to evaluate the removed moisture. The highest removal rate was observed at the beginning of the drying. The recommended time was appeared to be 8 h. The most efficient method was high temperatures annealing, but it should be taken into account that the treatment can result in micro-damages and aging. It is recommended to limit repetitions of the process as well as to store PCBs at temperature in the range of 20–25 °C and humidity below 5% RH. An alternative is an annealing at reduced pressure and elevated temperature or application of anaerobic chamber with nitrogen and moisture below 0.5 ppm. • Duration of moisture removal from FLEX/RIGID-FLEX/SEMI-FLEX PCBs using different methods of drying does not exceed 8 hours. • 8-hour drying is a compromise between the residual moisture and the impact of annealing on solderability and reliability. • Humidity of 5% RH slows down efficiently the process of removing moisture from PCBs at temperatures above 100 °C. • Reduced pressure at elevated temperature (drying in anaerobic chamber) is an alternative to annealing at temperature of 100 °C • The drying in a vacuum is three times cheaper than annealing the cost of which is similar to drying in a nitrogen chamber. • The drying in a climatic chamber is up to ten times more expensive than drying in an annealing chamber. [ABSTRACT FROM AUTHOR]