Guideline

PCB Vias Types: PTH Vias, Blind Vias, Buried Vias, and Back Drill Vias

PCB Vias

There are a total of 4 types of vias used in Printed Circuit boards like plated-through hole vias, blind vias, buried vias, and back drills. Different types of vias in PCB have different characteristics. Before we solder, we need to understand the various through holes, so that we can know the functions of the relevant through holes, and there will be no problems in subsequent component welding.

A Detailed Introduction of Different Types of Vias in PCB

1. Plated Thru Holes

Plated Thru Holes

  • Comprehension of Plated Thru Holes

One of the PCB vias types we can first discuss here is Plated through hole.Plated through hole vias goes from the top outer layer to the bottom outer layer. In this vias, the designer uses the minimum tools like 8 mil vias tool and 10 mil vias tool but they often prefer less than 20 mil vias size for vias.

But sometimes these vias are required to be filled with some material which is conductive material and nonconductive material for use to fill vias.

  • Different filling in Plated Thru Holes

Also, sometimes it requires copper fill and silver fill for vias due to the high-frequency board.

Vias hole’s inner walls are copper due to proper connection passes from one place to another place or one copper layer to another copper layer.

These types of PCB vias are sometimes plugged with solder mask material using the LPI method.

But some types of PCB vias such as Plug vias are required to cover both sides with a solder mask due to PLUG with LPI mask ink. 

  • The function of plated thru holes

Plated thru holes are mostly used for Component holes, these types of holes are specially designed as per component lead requirements. Plated thru holes are used to place components on board using the solder method.

The proper data sheet is required to create holes as per component lead in pcb to ensure proper insert in the Printed Circuit Board. Plated holes are not filled due to inserting component lead in those holes.

Plated holes in inner walls have copper due to the pass connection top to bottom copper layer and soldering to any side on which the components are placed.

 

2. Blind Vias

Blind Vias

  • Comprehension of Blind Vias

In many via types in PCB, blind vias are different types of vias in pcb that start with the top copper layer connection and pass to the inner copper layer and do not go to the outer other copper layer like the bottom copper layer.

  • The Function of Blind Vias

Blind vias are used to connect the outer copper layer to the inner copper layer.Blind vias are mostly used in multi-layer printed circuit boards and these types of PCB vias are used for the outer copper layer to the inner copper layer and these types of PCB vias do not go another outer copper layer like top to bottom not pass.Blind vias are mostly done as a filled vias and due to small vias and not passing as a thru vias. So blind vias are filled with non-conductive ink or conductive ink.

 

3. Buried Vias

Buried Vias

  • Comprehension of Buried Vias

One of the other via types in PCB is buried vias and it is used to connect between the inner copper layer and the inner copper layer and not go to any outer copper layer like the top and bottom copper layer.

These types of PCB vias are also filled with non-conductive ink or conductive ink or copper filled.

These types of PCB vias are connected to inner copper layer 2 to inner copper layer 5 if the board has 6 copper layers, not connected outer copper layer top and bottom copper layer.

  • The Function of Buried Vias

These types of vias are used because they are connected to the inner copper layer to the inner copper layer and after use, they have maximum room for the outer copper layer to run other components or other placement for trace or many more.

These types of PCB vias use the most complex printed circuit board and most of these types of PCB viasvias cost high in printed circuit board.

 

4. Back Drill Vias

Back Drill Vias

  • Comprehension of Back Drill Vias

Back drill vias are one of the PCB vias types mostly used as non-plated via after plated vias are done.

This type of vias is done after a full board is made. Any through or blind vias are done and then a Back drill to remove some connections to the layer. So back drill is used to create plated vias to convert into non-plated vias for some layer and after that vias are plated.

This type of via also called controlled depth drilling, this type of vias removes some copper over plated vias and removes plating and connection after PCB is done.

 

  • The Function of Back Drill Vias

These types of vias are used to break connections at particular locations and from particular layer to layer because these types of vias are controlled depth using a special process.

 

This method is used for breaking annular rings and copper barrel plating over plated vias.

This technique is used in fast signal connection and fast impedance requirements.

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