The present invention provides an implant device comprising a shell and a printed circuit board for mounting electronic components, wherein the shell surrounds the printed circuit board and defines a large area for large electronic components mounted on the printed circuit board and a small area for smaller electronic components. The shell has a shape that is curved. The shell may consist of two layers, with one layer being thicker. Also one layer may provide openings or feedthroughs for connecting the implant to other components, such as coils and electrode arrays.