Via PCB-Valuable Introducing It's Here(Helpful)

Abstract

The different layers of a Printed Circuit Board are connected together through electrical connections made by vias. The Via PCB are used to transfer power or signals from one layer of PCB to the other.Plated through Technology is mainly used in vias utilized in back plane designs.

 

These types of vias will make connections between the signal layers on the inner side of PCBs and the pins on the connectors. They are made from a hole drilled on the layers on which connections are to be made followed by plating the drilled hole using copper.

 

Another type of vias on PCB is High Density Interconnect (HDI) vias. These are also commonly referred to as micro vias and are made by drilling very tiny holes in the layers on which connections are to be made.

 

Content

1.Via Aspect Ratio

2.Back drilled via

3.Blind via /Buried via

4.Through via PCB

5.Stub via PCB

 

 

1.Via Aspect Ratio

This term refers to the ratio of thickness of printed circuit board to the diameter of the smallest non plated hole drilled on the circuit board. This ratio is great importance especially when developing a design for your stack up and also when giving specifications for the smallest size of holes to be drilled on your PCB design.

 

To Achieve a more consistent plating on the vias drilled on the circuit board, the via aspect ratio used is low. Vias whose walls have a plating thickness of 2 mil are more referred. Vias whose aspect ratio is high will have less plating at the middle while more plating will be applied on the ends.

Expansion on the Z axis during the soldering process results in an increase in incidences of vias whose barrels are cracked.

 

To ensure that your PCB is suitable for fabrication from anywhere, the aspect ratio should be maintained at 6:1.The best PCB shops have the ability to fabricate circuit boards whose aspect ratio is 10:1 and whose drill diameters don’t exceed 0.02”

A through hole via should have a minimum drill diameter of 0.013” since this is the least practical size possible. A circuit board with via aspect ratio of 10:1. Should have a maximum thickness of 0.13”  

 

 

2.Back Drilled via

Back drilling is defined as the process of removing a stab from a plated through hole via. It is a drilling procedure applied after fabrication of a printed circuit board in a situation where the hole on which back drilling is done has a diameter larger than that of the initial plated through hole.

Back drilling is commonly done on the via stub of Printed Circuit Boards with high thickness. This is done to ensure the length of stub whose bit rates are higher than 3Gb per second is maintained at minimal level.

 

3.Blind or Buried Via

Blind vias and buried vias are ordinary vias, the only difference being that they do not penetrate through the entire length of the circuit board.  Blind vias are used to create connections between a single or multiple layers within the boards to a single layer on the exterior of the board. Buried vias are holes with plating that are drilled within the board which remains buried in within the layers of a printed circuit board.

 

 

4.Through Via PCB

These types of vias are the simplest to use and have been in use for the longest period of time. Initially they were used in Printed Circuit boards with a 2-4 layer design. They lack stubs because the origin and terminal points of signals are at external layers of the circuit boards. Through vias are used in applications of PCB that have multiple layers as a cheap alternative of eliminating resonance produced by stubs in a situation where other methods are either too costly or impractical.

 

5.Stub Via PCB

Stub vias are the most common types used in printed circuit boards today. They are similar to other types of vias in that they penetrate from one end of PCB to the other end. They differ in that they connect single or multiple layers located on the inner side of PCB.

 

 

 

Conclusion

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