An ultra-high vacuum (UHV) compatible feedthrough structure and a detector assembly using such feedthrough structure, the feedthrough structure comprising a printed circuit board (PCB) for carrying one or more detectors, wherein said PCB comprises a top surface covered with a first UHV sealing layer and one or more first electrical electrodes and at least a first thermally conductive layer extending at least partly over said top surface; and, a back surface comprising one or more second electrodes and at least a second thermally conductive layer extending at least partly over said back surface, wherein one or more conductive wires are embedded in said PCB for electrically connecting said one or more first electrodes with said one or more second electrodes respectively; and, wherein one or more thermally conductive vias are embedded in said PCB for thermally connecting said at least first thermally conductive layer with said second thermally conductive layer.