How to distinguish between through hole, blind via and buried via in PCB?

In the PCB design and manufacturing process, we usually use through hole, blind /buried via to meet design needs and performance requirements. So what is the difference between them?

1.Through hole

A through hole is a relatively simple and common type of holes in PCB. It is created by drilling a hole in the PCB (top layer to bottom layer) and filling it with a conductive material (such as copper). Often used to connect circuits at different layers to provide electrical connections and mechanical support.

 The cost of through hole is relatively cheap, but for high-density HDI circuit board design, as the space of the circuit board is very precious, the through hole design is relatively wasteful.

2.Blind via

Blind via is similar to through hole, but blind via only partially passes through the PCB. It leads the top layer to the inside without penetrating the PCB. Usually used to connect circuits between surface and inner layers, very suitable for multi-layer PCB with limited space. The manufacturing process of blind via is relatively complicated. Failure to pay attention to the drilling depth can easily cause difficulties in electroplating in the holes. Therefore, the circuit layers that need to be connected can be drilled first when they are separate circuit layers, and then all are bonded. However, using this method requires accurate positioning and alignment devices. Therefore, blind via is more expensive than through hole.

3.Buried via

Buried vias are hidden inside each layer of the PCB and connect two or more inner layers of the PCB. They are invisible to the surface and bottom layers. They are usually suitable for high-density HDI circuit boards to increase the usable space of other circuit layers. For the production of buried vias, drilling operations can only be performed on individual circuit layers first. The inner layer is first partially bonded and then electroplated, and then all bonded. Because the operation process is more laborious than the original through hole and blind via, the price is more expensive.

Tips:

Price: Through hole＜Blind via＜Buried via

Space utilization: through hole＜blind via＜buried via

Operation difficulty: through hole＜blind via＜buried via

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