A method for producing rotomoulding polyethylene by fluidized bed gas phase polymerisation of ethylene and the improved rotomoulding polyethylene obtainable by the process. The semiconductor package further has a housing molded over and encapsulating the semiconductor chip with the frame such that a surface of the semiconductor chip facing away from the cupped strip is flush with or protrudes beyond a bottom of the housing. The second fluid generally is substantially different from the first fluid.