An adapter (1) with at least one electronic component (2) for mounting in a hole (3) extending through or partly through a composite board (4), which includes at least two layers (5) of electrically conducting material that are separated by at least one insulator (6) of electrically insulating material, the adapter (1) including one or more legs (7) adapted for by mounting in the hole (2) to establish electric connection with a first layer (8), and where the at least one component (2) is fitted on a metal item (9) which has a contact surface, and that the contact surface is in electrically and thermally conducting connecting with a contact surface on a second layer (10) when the adapter (1) is mounted in the hole (3).