Blind buried vias: they connect the outermost circuit of PCB with the adjacent inner layer by electroplating hole. They are called blind vias because the opposite side cannot be seen. In order to increase the space utilization of PCB circuit layer, the "blind vias" process has emerged. This method requires special attention to the drilling depth (Z-axis) to be appropriate but this method often causes difficulties in electroplating in the hole, so almost no manufacturers have adopted it. It is also available to drill holes in individual circuit layers in advance and then stick them together. However, more precise positioning and positioning devices are required.
The blind vias are located on the top and bottom surface of blind via PCB, and has a certain depth. It is used to connect the surface circuit and the inner circuit below. The depth of the hole usually does not exceed a certain ratio (aperture).
Unlike plated through hole PCB (PTH PCB), the application of blind via hole and buried via hole in blind and buried via technology can greatly reduce the size and quality of PCB, reduce the number of layers, improve the electromagnetic compatibility, increase the features of electronic products, reduce the cost, and make the design work easier and faster.