The PCB via technique in electronic PCB fabrication
“Via” is widely used in the PCB design and manufacture of a multi-layer PCB. Each hole on the PCB can be called a visa. The circuit board is made up of layers of copper foil PCB circuit superposition, and the connection between different circuit layers is the guide hole because the manufacturer of the printed circuit board uses drilling holes to connect to other circuit layers, the purpose of communication is to conduct electricity, called the through the hole, At the same time, it is necessary to plate a layer of conductive material on the drilled surface (usually copper) so that the electrons can move between different layers of copper foil.
Classification of via
1.Plating Through Hole(PTH)
This is the most common and the most simple way to pass the hole, the cost is relatively cheap, as long as the use of a drill bit or lightning light directly to do the circuit card assembly full drilling is completed.
2.Blind Via Hole（BVH）
The blind hole is located at the top and bottom surface of the printed circuit board, with a deep connection between the surface line and the inner line. The outermost circuit of the PCB connects with the adjacent inner layer with electroplating holes. Because the opposite side cannot be seen, it is called the blind hole. The blind hole was used to increase the space of the PCB.
3.Buried Via Hole（BVH）
The buried Via hole is the connection hole located in the inner layer of the printed circuit board, which does not extend to the surface of the circuit board. The inner layer of the above two types of hole circuit board is completed by the through-hole forming process before lamination, and several layers may overlap in the process of overhole formation. The connection of any circuit layer inside the PCB is not connected to the outer layer.
4.uVia
U via are very small over holes for spatially limited high-density PCB. The inner layer used to connect the PCB generally has a maximum diameter of 0.15 mm, a maximum aspect ratio of 1:1, and a maximum depth of 0.25 mm. U visas are well adapted for high-speed signals and are commonly used in mobile phones and other compact electronics.
5.Via-in-pad
The high signal speed, as well as the thickness and density of the PCB components, have generated the Via-in-pad method. Standard perforated structures and VIPPO can guarantee the wiring capability and integrity of the signal. The inner hole in the inner hole of the pan is placed in the welding pan of the external mounting element. The overhole in the pad has two advantages: signal path expansion, and eliminating the influence of inductance and capacitance. Reduce the PCB plate size and accommodate the small grounding size.
How do I choose a hole in my PCB designing?
Unlike through holes, blind holes and buried holes are only suitable for at least four layers of circuit boards. Using blind or buried holes is an effective way to increase the density of multi-layer circuit boards and reduce the number of layers and circuit board size.PTH are easier and cheaper to make and are therefore more commonly used in PCB designs.
