The present invention provides a signal conversion device comprising: a substrate having a first surface and a second surface, the first surface being provided with a first contact region comprising at least a first contact and a second contact while the second surface being provided with a second contact region comprising at least a third contact and a fourth contact; wherein there is an electrical connection between the first and third contacts, and the second and fourth contacts are electrically connected to an IC fabricated using Wafer Level Chip Scale Package (WLCSP) or Chip On Film (COF) technology, and wherein the IC is disposed at the first surface or the second surface.