Advantages of blind vias and burying through PCB blind buried vias:

  Eliminate a large number of through-hole designs, improve wiring density and packaging density;

  Diversify and complicate the internal interconnection structure design of the multilayer board;

  The reliability of multi-layer boards and the electrical performance of electronic products have been significantly improved.

  Buried hole design and production:

  Compared with the traditional multi-layer board, the production process of the blind and buried via circuit board is more complicated and the cost is also higher. Buried hole, ordinary through hole and PAD size are general specifications.

  Blind and buried via circuit board design and production:

  The upper and lower layers of the circuit board with extremely high-density double-sided SMD design will move up and down, and the I/O vias will interfere with each other, especially when the via pad design is used, which is even more troublesome. Blind holes can solve this problem. In addition to the popularity of radio communications, the design of the circuit must also reach the RF (radio frequency) range, which exceeds 1 GHz. The blind hole design can meet this requirement.

  There are three different methods for the production process of blind and buried vias:

  1. Mechanically fixed depth drilling

  In the traditional multilayer board manufacturing process, after pressing, a drilling machine is used to set the Z-axis depth. However, this method has several problems:

  Only one drill bit at a time will produce very low output

  The height of the drilling machine table is strictly required, and the drilling depth of each spindle must be consistent, otherwise it is difficult to control the depth of each hole

  Electroplating in the hole is difficult, especially if the depth is greater than the diameter of the hole, it is almost impossible to electroplate in the hole.

  The limitations of the above method make this method gradually not used.

  2. Sequential lamination

  Taking an eight-layer board as an example, the continuous pressing method can make blind holes and buried holes at the same time. First, make four inner boards in a general double-sided skin and PTH method (other combinations can also be used; six-layer double-sided boards, upper and lower double-sided boards + inner four-layer boards), and then press the four pieces together, A four-layer board is formed. Complete the production of through holes. Compared with other methods, this method has a longer process and higher cost, so it is not universal.

  3. The non-machining method of establishing the process

  At present, this method is favored by the global industry, but the domestic industry cannot tolerate it. Many large factories have manufacturing experience.