Reliability investigations of a sensor system embedded into printed circuits boards

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. (© 2020 Wiley‐VCH GmbH)