X-ray tomographic view of Printed Circuit Board microvias

X-ray tomographic view of Printed Circuit Board 'microvias', laser-drilled connecting holes just 175 micrometres, or a small fraction of a millimetre, across, linking adjacent layers of high-density interconnect printed circuit boards, HDI PCBs. This shows the PCB footprint for a grid array EEE component with HDI routing, showing two microvia layers underneath the solder pads, as well as a long buried via in the core of the PCB.