Abstract: A method of protecting active and passive electronic components on a portion of one surface of a multilayer substrate of a micropackage from deleterious constituents of the ambient atmosphere, primarily water vapor. A segment of a thin, flexible, substantially nonpermeable and nonadhering membrane, or sheet, has its perimeter secured to the substrate by a bead of sealant adhesive. The exposed surface of the segment has applied to it a thicker coating of a substantially nonpermeable sealant adhesive material which adheres to the membrane and the bead of sealant adhesive. A small opening is formed through the coating and the segment to provide communication with the area between the surface of the substrate on which the components are mounted and the inner surface of the segment. The substrate is placed in a chamber which is substantially evacuated to remove gases trapped under the segment.