An integrated circuit package includes a flexible laminar substrate 1. The substrate 1 has a flexible layer 5 of heat conductive material on one of its faces. The layer 5 extends across an aperture 9 in the flexible substrate 1. A first integrated circuit 11 is mounted on the layer 5 within the aperture 9, and wire bonded to the substrate 1. A flip chip 21 is mounted on the first integrated circuit 11. The two integrated circuits 11, 21 are embedded in a resin body 23.