Low-temperature properties of capacitors embedded into Printed Circuit Boards

This paper presents low-temperature properties of capacitors embedded in Printed Circuit Boards. Planar capacitors, differed in composition thickness and surface size, were fabricated from FaradFlex dielectric foil with copper plates laminated to FR-4 substrate. The dielectric tapes were polymer or BaTiO3/polymer compositions with various dielectric constants. The investigated capacitors were covered with LDP 2×106 (Laser Drillable Prepreg) protective layers to achieve embedded structures. The temperature dependences of capacitance as well as dissipation factor (i.e. C(T) and tgδ(T) characteristics) were investigated for two values of frequency (1 and 10 kHz) in a wide temperature range between −180 °C and room temperature. Moreover durability of capacitors to low-temperature thermal shocks (between liquid nitrogen and room temperature) are reported and analyzed.