Overview of PCB Blind via and Buried Via

Overview of PCB Blind via and Buried Via

Similarly, there is another kind of via known as micro via which is comparatively smaller than other types of vias. This type of via is the favorite among PCB designers due to smaller diameter, greater space for routing on the PCB board and have lower parasitic capacitance in high-speed circuits and systems.  Nevertheless, there are some disadvantages of micro via such as needing more time for drilling and off-center via moves. As per the rules of ONESEINEPCB, the diameter of the micro via is kept as lower as 0.1 mm in PCB designing boards.

Blind via and buried via is new PCB manufacturing technolocgy to meet the Increasingly complex electronic design requirements, What are these vias and how they are important and have significant role in PCB manufacturing both for consumers and the manufacturers and how these terms are different from each other are discussed in this article. Also, this article will put some light on other via types i.e. stacked via and micro via. Before understanding these vias, it is important to understand “via” in PCB design manufacturing.

Description of  PCB Via

In PCB designing the term “via” is extensively used. It is actually the connection source in the form of copper-plated hole which connects different layers in the PCB. Different vias can be used but the most widely standard via used across the world in every PCB is the through-hole via. Several disadvantages are associated with through-hole via specifically in surface mount technological applications. Because of these disadvantages, through-hole vias are replaced by two additional vias such blind via and buried via. Both these vias (blind and buried) have processing in a variety of different measuring features which include plugged copper mask via, plugged solder mask via, plated via and staggered via. A simple comparison of through-hole via, blind via and buried via is depicted in Figure below.

Blind Via vs Buried Via

Both blind and buried vias are used for connection of different PCB layers. What are the major differences in these types of vias are discussed in this section? The blind via provides an interconnection of the outer layer with a single or multiple inner PCB layers whereas only inner layers are interconnected in the buried via and the board is completely kept hidden and invisible from external environment of the PCB. Both these vias have great advantages in HDI PCB  due to their optimal density deprived of increase in the size of board or requiring the number of layers in the PCB board.

There is another classification of PCB board via and known as stacked via and micro via. These are discussed in the next section along with their pros and cons.

The stacked via is basically meant for improving further the size and density of PCBs during the process of their manufacturing. These two factors have great importance in todays’ modern miniaturizing and high transmitting signaling with requirements of speed in several applications and areas. If there is a consideration of blind via having a 1:1 or more aspect ratio or the process of drilling requires multiple layers to cover then the best way to get the interconnection among the layers  can be stacked via. Additionally, the lamination of stacked via is either by blind or buried for building multiple layers within the circuit board to be built together around the same origin or central point whereas there is no lamination around the center in the staggered via.

Several advantages are associated with the stacked via such as providing greater space in the board by saving the area, enhances the overall density, better in terms of flexibility in terms of internal connection, capacity of better routing and minimum parasitic capacitance. Similarly, the most important and bigger disadvantage of stacked via is their highest cost as compared to the standard through-hole via or blind and buried via that significantly reduces their use by common or student designers and favorite among the people working in bigger professional environments.