A buffer material protects a microelectronic device in space constrained environments, for improved efficiency with respect to magnetostrictive materials therein, and includes a gas filled polymer shell microsphere carried in an elastomeric polymer binder. Expanded Expancel microspheres being less than 20 microns in diameter form 80% of the composition by volume. The polymer binder is a low viscosity dimethyl silicone with a hardness of less than 25. Coating thicknesses may be based upon the overall expected dimensional changes of the encapsulation material, due to its coefficient of thermal expansion and an expected operating temperature range of the component, plus the expected shrinkage of that encapsulation material during polymerization and the overall mass which shall be exerting a force upon the magnetic core, plus the dimensional changes of the component as a result of the flux density resulting in magnetostriction of the magnetic core.