An improved Quad Flat No-Lead package is described. The package is formed by encapsulating a die mounted on a leadframe with a moulding compound using a mould chase. The mould chase comprises a number of internal projections which form openings in the mould compound to expose regions of the leadframe. These exposed regions of the leadframe may then be used for soldering the package to a substrate. The arrangement of the openings may be designed such that each aperture is the same shape and size and/or that the apertures are arranged in multiple rows on the underside of the package.