In one embodiment the cover comprises cut-outs in its surface corresponding to, and facing, the circuit elements on the substrate (e.g. the circuit elements arranged on the face of the substrate facing the cover) so to space the cover from the circuit elements on the substrate.

In one embodiment the cover is spaced from the (e.g. (entire) face of the) substrate so to space the cover from the circuit elements on the substrate.

The cover may be spaced from the substrate in any suitable and desired way. For example, the recess in the holder may have a depth that is greater than the thickness of the substrate, so that the face of the substrate facing the cover is spaced from the cover. In another example, the cover may comprise a recess such that the cover is spaced from the substrate. In another example, the projection(s) on the holder may have a height that is greater than the thickness of the substrate, such that the projection(s) project through and beyond the thickness of the substrate, so to space the cover (which, e.g., is arranged to abut against the projection(s)) from the substrate.

When the substrate comprises circuit elements on the face of the substrate facing the holder, preferably the (e.g. surface of the) holder is configured to be spaced from the circuit elements on the (e.g. face of the) substrate, e.g. in a similar manner to the cover. Thus, for example, the holder may comprise cut-outs in its surface corresponding to, and facing, the circuit elements on the substrate (e.g. the circuit elements arranged on the face of the substrate facing the holder) so to space the holder from the circuit elements on the substrate.