The role of blind vias is to conduct the left and right sides, so as to ensure the reliability of the circuit board! Blind holes are distributed in some layers, and buried holes are distributed in the middle layer, and through holes are distributed in all layers. Blind holes generally return All are drilled by LASER laser drilling machine, while buried holes and through holes are generally drilled by mechanical drilling.
What are the functions of blind holes in four-layer circuit boards?
In the non-through via technology, the application of blind and buried vias can greatly reduce the size and quality of the circuit board, reduce the number of layers, improve electromagnetic compatibility, increase the characteristics of electronic products, reduce costs, and also make design work Easier and faster. In traditional circuit board design and processing, through holes will bring many problems. First, they occupy a large amount of effective space, and secondly, a large number of through holes are densely packed in one place, which also creates a huge obstacle to the inner wiring of the multilayer circuit board. These through holes occupy the space required for wiring, and they intensively pass through the power supply and The surface of the ground layer will also destroy the impedance characteristics of the power ground layer and make the power ground layer fail. And the conventional mechanical method of drilling will be 20 times the workload of non-through hole technology.
In the circuit board design, although the size of the pads and vias have been gradually reduced, if the thickness of the board layer is not proportionally reduced, the aspect ratio of the via will increase, and the increase of the aspect ratio of the via will reduce the reliability . With the maturity of advanced laser drilling technology and plasma dry etching technology, it is possible to apply non-through small blind holes and small buried holes. If the diameter of these non-through vias is 0.3mm, the parasitic parameters will be About 1/10 of the original conventional hole, which improves the reliability of the circuit board.
Due to the non-through via technology, there are few large vias on the circuit board, which can provide more space for routing. The remaining space can be used for large-area shielding purposes to improve EMI/RFI performance. At the same time, more remaining space can also be used for the inner layer to partially shield the device and key network cables, so that it has the best electrical performance. The use of non-through vias makes it easier to fan out the device pins, making it easy to route high-density pin devices (such as BGA packaged devices), shortening the wiring length, and meeting the timing requirements of high-speed circuits.