CONCLUSIONS
A study of the effect of harsh environmental
conditions on the resistivity and permittivity of insulators
is presented. The study focuses in the humidity effect for
the electrical properties of thermal compound and/or air.
The proposed models are applied to an application
example circuit for high voltage operation where the
humidity effect is noticeable.
Two approaches have been investigated to address the
problem of modeling external components under variable
environmental conditions. The first method calculates the
resistivity variation of materials involved during the
manufacturing and assembly of power electronic systems.
The second approach quantizes the capacitance created by
placing a metallic enclosure in a close vicinity of a
sensitive circuit is proposed. The model takes into account
the variation of permittivity with humidity.
The proposed methods not only take into effect the
environmental conditions but also the mechanical
properties of the electrical system. Alternatives for design
to counteract the disturbances generated by the variation of
environmental conditions may include: modifying
dimensions of mechanical components, altering the
placement of components in the PCB, or modifying
routing of exposed conductive layers.
The above contributions begin to provide the designer
with the understanding of the environmental conditions
influence over sensitive circuitry. Furthermore, the
proposed method provides a way to quantize the effects at
given environmental and mechanical conditions, and more
importantly, provides a way to achieve an efficient use of
space for worst case environmental conditions.