Two integrated circuits 1, 3, 101, 103 having circuitry on one of their major surfaces 11, 31, 111, 131 are ground on their opposite major surfaces 13, 33 to reduce their thickness. The ground integrated circuits are then adhered together to form a composite body 7 and placed in a chamber 97, 197 formed within a substrate 9, 109 such as a printed circuit board. Electrical connections are formed between contacts 15, 35, 115, 135 of the integrated circuits 1, 3, 101, 103 and contacts 92, 192 of the substrate 9, 109. Components 22 may be mounted on the outer surfaces 24 of the substrate 9, 109.