A method includes populating components in a cavity of a substrate, disposing a polymer over the components and within the cavity. The polymer is cured and a thin film is formed on the polymer. In addition, a method includes forming an EMI shield within a medical device by depositing a thin film of metal on a surface within the medical device. The thin film of metal, of gold, aluminum, or copper, is formed by vapor deposition or sputtering. An apparatus includes a first substrate assembly including a first substrate having a cavity. A first set of electronic components are disposed within the cavity, and a first polymer is disposed over the first set of components. Deposited on an outer surface of the first polymer by vapor deposition is a thin film of metal. The thin film of metal is electrically coupled with a ground. A second substrate assembly including a second substrate is coupled with the first substrate assembly.