Abstract:

In this work the reliability of an embedded planar capacitor laminate under a variety of environmental stress and bias conditions is investigated. The capacitor laminate consisted of an epoxy-barium titanate (BaTiO₃) composite dielectric of 8 μm thickness sandwiched between two layers of copper of 35 μm thickness. The composite dielectric consisted of BaTiO₃ particles of 0.25 μm mean diameter loaded to 45% by volume in a bisphenol-epoxy matrix. The capacitor laminate was embedded in a 4-layer test board. The power plane of the capacitor laminate was etched to form discrete embedded capacitors having a common ground plane. Capacitors of area 0.026 in² and 0.19 in² were investigated in this work; their capacitance was close to 400 pF and 5 nF, respectively. The test vehicle with embedded capacitors was subjected to temperature and voltage aging and temperature humidity- bias (THB) tests at different stress levels. Three parameters, capacitance (C), dissipation factor (DF), and insulation resistance (IR), were measured in-situ. An LCR meter was used to measure capacitance and dissipation factor during stress testing. A high resistance meter was used to measure insulation resistance. Results are presented of testing at multiple stress levels in temperature and voltage aging tests and THB testing. Changes in electrical parameters during stress testing are reported, as well as the effects of stress conditions and levels on characteristic life. Physical analysis is used to identify the material response of the embedded capacitor laminate to the imposed stresses, providing the basis for recommendations regarding laminate design and usage.

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