barrier structures are included within the packaging material of a packaged semiconductor device , such barrier structures including barrier bodies which overlie the die - die pad assembly of the device on either side thereof . the barrier bodies act as baffles which limit diffusion of moisture through the packaging material into the area of the die - die pad assembly of the device , the barrier bodies including apertures therethrough which control such diffusion in a manner that avoids delamination problems in the area of the die - die pad assembly , meanwhile also avoiding undesirable trapping of gas within the packaging material .