Abstract: A cap and seal including a central cap (20) to be positioned over an electronic component such as an integrated circuit chip (12), has a spaced upstanding wall or dam (22) which may be staked to the circuit board in assembly forming with the peripheral side wall (21) of the cap a channel or moat (19). Bridging means (24) extend between wall (21) and wall (22) onto which is placed a preform ring (30) of solid sealant material. Heating of the assembly, more particularly ring (30), allows melted sealant material to flow under and around bridging means (24) to form a confined seal between wall (21), wall (22) and an annular surface (29) on the circuit board surrounding cap wall (21).