An interface device is provided between a test head and a device under test (DUT). A socket board includes sockets each configured to mount a DUT, and a socket PCB having a first face that mounts the sockets and a second face provided with multiple back face electrodes. An interposer has a first face provided with multiple deformable electrodes and a second face provided with multiple non-deformable electrodes and is configured such that the multiple deformable electrodes are in contact with the multiple back face electrodes of the socket PCB. An FPC cable has multiple electrode pads to be coupled with the multiple non-deformable electrodes on the second face of the first interposer.