Mechanical reliability of ceramic packages for active implantable medical devices - The IEC hammer test

摘要

Implantable neural prostheses have to fulfill manifold requirements, from the technological side as well as legally. One particular normative demand for active implantable medical devices (AIMDs) which are intended to be implanted in the skull, is withstanding a mechanical impact of 2.5 J, defined by BS EN 45502-2-3:2010 and IEC 60068-2-75:1997. This article shows two computational approaches based on finite element modeling to evaluate the influence of geometrical variations on a brain-computer interfaces' mechanical package stability and the likelihood of withstanding mechanical impact. The presence of a fillet at inner edges (>0.5 mm) as well as a minimum wall thickness of 1 mm could be identified as a mandatory design requirements for axially symmetric packages to avoid extensively high stress levels. Mechanical event simulation (MES) predicted a passing of the hammer test if additional protective material (silicone rubber) is used. This however is postulated by the EN 45502-2-3 standard. The computational findings could be confirmed in a laboratory setup of the impact test.