Sealed dome switch for mobile electronic device

A mobile electronic device (MED) comprising:

• a housing defining a recess;
• a dome switch assembly to initiate a function of the MED, the dome switch assembly having a substrate with a passageway defined therethrough, the substrate also having a perimeter, the dome switch assembly further having an outer layer in direct contact with the substrate, the outer layer being secured to the substrate, the outer layer having a dome actuation portion, the outer layer also having a ledge that extends beyond a portion of the perimeter, the dome actuation portion including an electrically conductive element, the substrate having an electrode formed on a side of the substrate that faces the dome actuation portion, the dome actuation portion and the substrate defining a dome volume therebetween, the dome switch assembly being secured to the housing to seal the recess from an outside environment of the MED, the passageway fluidly connecting the dome volume and the recess to allow fluid from the dome volume to flow through the passageway, and into the recess, upon depression of the dome actuation portion, the depression of the dome actuation portion to cause the electrically conductive element to contact the electrode to initiate the function of the MED, the housing having a securing surface with which the substrate is in direct contact and to which the substrate is secured, the housing further having a step extending from the securing surface, the step having a top to which the ledge of the outer layer is secured.