Apparatus for providing a low permeable interface in a hermetically sealed housing. The housing includes a substantially planar housing member with an aperture extending therethrough. An electrical feedthrough assembly extends adjacent the aperture to provide one or more electrical signal transmission paths. An elastic ring couples a peripheral edge of the electrical feedthrough assembly to the housing member to form a low permeable interface therebetween. The ring preferably operates to compensate for the differential between the coefficients of thermal expansion of the feedthrough assembly and the housing member. The ring is preferably provided with an elongated cross-sectional shape with a segment that extends in a direction non-parallel to a longitudinal axis of the feedthrough assembly, thereby enhancing the spring characteristics of the ring. The housing is preferably characterized as a housing of a data storage device, and retains an inert gas atmosphere, such as at least 95% (w/w) helium.