Q: What is a blind/buried via board? What is the difference between blind via PCB and buried via PCB?
From the end of the 20th century to the beginning of the 21st century, the electronic industry of circuit board has developed by leaps and bounds, and the electronic technology has been improved rapidly. As a printed circuit board industry, only by developing synchronously with technoloy, can we continuously meet the needs of customers. With the small, light and thin volume of electronic products, PCB has been developed into flexible board, rigid flexible board, blind/buried hole circuit board and so on.
When it comes to blind and buried vias, let's start with traditional multilayer boards. The structure of standard multilayer circuit board is composed of inner circuit and outer circuit. The inner connection function of each layer of circuit can be achieved by using the process of drilling and metallization in the via. However, due to the increase of circuit density, the packaging methods of parts are constantly updated. In order to make the limited area of circuit board, more and more high-performance parts can be placed. In addition to the narrower circuit width, the aperture of dip jack is also reduced from 1mm to 0.6mm of SMD, and further reduced to less than 0.4mm. But it still occupies the surface area, which leads to the formation of buried vias and blind vias. The definitions of buried via and blind via are as follows:
A. Buried vias
The through hole between inner layers. It can't be seen after pressing, so it doesn't need to occupy the outer area. Both the upper and lower sides of the via are in the inner layer of the board, in other words, it is buried inside the board.
B. Blind vias
They are through holes applied to the surface layer and one or more inner layers. One side of the via is on one side of the board, and then the via goes through the board till reaches the inside of the board.