Plated through hole vs via seems like an easy and straightforward topic to be discussed. Moreover, there are important information you should know regarding the two. Therefore, some explanation will assist you in understanding the way both operate, as well as their differences.
In the inner layer of plated through holes, you will find a metal layer coating. The holes help in connecting the different layers present on a circuit board. Importantly, the plated through hole are usually integrated where components require a great electrical connection such as integrated circuits, switches, and connectors. Electroplating helps in creating a plated through hole, and the process deals with the utilization of chemicals for creating the plated through hole.
Several components play significant roles in the functioning of circuit boards. PCB via forms one of these components. In modern electronic devices, you will find a small green board which helps in transmitting different signals. The via is an important building block of PCB design.
Explaining further, a printed circuit board is found in any smartphone, which contains different chips and components that perform signals for different commands and features. Each time the screen is touched, one of the board’s signals is activated immediately. Majority of the signals are performed by these vias.
What Does Plated Through Hole Mean?
Plated through holes are described as holes that are drilled in conductive materials. The technician helps in attaching the circular pad on the top as well as underside region of the hole during the through hole assembly. Circular pads help in creating the connection in-between the hole and traces of the circuit board. The hole’s inner part that links the conductive metal-plated pads links both sides.
With plated through holes, there will be current flow through the components on ones of the PCB sides, through the non-conductive substrate, as well as to the board’s other side. Furthermore, the plated through holes make sure circuit boards can firmly hold the components on both sides. Having this, the designer will be able to efficiently maximize space.
To accommodate more components, circuit boards have to be larger. The circuit boards utilized in large devices or machines would require a larger size circuit. Moreover, the smaller devices incorporate the smaller printed circuit. Integrating the plated through holes needs the circuit board to be stacked vertically. Therefore, this aids in reducing the circuit board’s overall size. It also ensures the circuit can accommodate additional components
What is the Significance of the Plated Through Hole?
Plated through holes are manufactured to ensure that components can connect with conductive layers. These plated through holes provide great electrical conductivity as well as desired functionality in circuit boards. The plated through hole comes with different benefits, which include faster prototyping. With PTH, manufacturers will solder components easily on circuit boards.
In addition, the plated through holes would provide manufacturers will great power tolerances as well as component durability. The holes ensure excellent connections. PCB manufacturers love using plated through holes because it offers great benefits.
Process of Plated Through Hole
For vias, the circuit boards come in different sizes. Furthermore, the boards have different component pins. In this section, we will consider the process involved in plating the through hole in circuit boards during fabrication.
- The process of plating begins after heat and pressure has been used for the circuit boards and the drilling of the through holes have been completed
- The technician goes ahead to clean the through holes so as to get rid of any residue. Also, debris may leave some residual resin inside the holes or you may find other contaminants. This is why chemical agents and abrasive processes are necessary for cleaning
- Next, is the chemical coating of a copper layer on the circuit board surfaces through the holes. Depositing the electroless copper provides a reliable based inside the holes for copper plating.
- Then the circuit board fabricator micro-etches the inner party of the holes. This aids in improving the copper base so as to hold properly during plating.
- A circuitry is then created on its external layers. This is achievable through exposing an image on the photoresist. Also, its inner layer utilizes the same process; the only difference is the integration of the reversed image.
- The material left unexposed is removed with the help of a chemical. This helps in increasing the weight of the metal. Once through, you have been able to achieve the plated through hole.
What Does a Via Mean?
Via can be described as metallic hole which connects into a circuit board’s circuitry. The hole helps in carrying the electrical signals out between the different layers of a printed circuit board. Furthermore, vias can be described as holes which pass through the board layers to ensure conductivity. Each hole provides a special conductive pathway whereby electric signals can transmit between the circuit layers.
In addition, the vias usually pass through different layers on the PCB. The design of the board would determine if this hole would pass through the whole layers. Some vias only passes through the bottom or the top layer. This is why PCB manufacturers and designers have to perfectly understand what their roles are.
Also, the blind vias functions as electrical connections present in between the multilayer board layers. The utilization of the vias for the board connection ensures the easy reduction of PCB sizes. Furthermore, the manufacturers can ensure that the via hole is conductive through the placement of copper cylinders inside these drilled holes. They then fill the via’s inner layer with any non-conductive material.
Types of Vias
Vias comes in different types. Moreover, the main group of vias regarding how they are placed inside the board layers is the buried and blind vias
What is blind via?
Blind via can be described as a hole, which penetrates the topside or bottom layer of a printed circuit board. Moreover, you won’t be able to see through the blind vias whenever a PCB is held to the light; this via looks hidden. Manufacturers drill as well as electroplate the blind vias from the top or bottom layer and into the internal layer.
Blind vias drilling could be achieved with laser or done mechanically. In addition, you must be accurate with the blind via’s drilling depth. In addition, it is possible to drill the blind via directly on the printed circuit board. Moreover, it can be extremely difficult to drill the blind via. This is one important reason why majority of PCB manufacturers don’t use the blind via.
What is Buried Via?
Buried vias can connect a PCB’s inner layer. It is also appropriate for dense routing circuit boards. Manufacturers can drill as well as electroplate the holes found in-between the PCB’s inner layers. In addition, buried vias helps in linking circuits between these inner layers.
Buried vias can be directly drilled on the circuit boards; that’s if it is connecting at least four inner layers. This is why manufacturer will only be able to drill holes on the required layers of the PCB. Furthermore, you cannot see the inner layer’s buried vias with your naked eyes.
What are the Other Via Types?
Vias come in other types and these are based on where they are located.
Through-hole
This is the most obvious type of via. This type of vias can penetrate the entire layers of any multilayer PCB. Its holes are larger compared to that of the buried and blind vias. You can easily identify this via type using your naked eyes. Just hold the via before light and the light would pierce through allowing you to see it.
Furthermore, creating through hole vias is very easy. You just have to drill through the layers. These manufacturers make use of through hole vias for the plated through hole technology.
Microvias
Microvias can be described as vias below 150 microns. They are used widely on some HDI PCBs. In addition, they are preferable since their hole size is small. The hole’s size takes minimal space on circuit boards. For this via type, the layer will connect onto each other with the help of copper plating.
Via-in-Pad
This via is included among the most popular vias. This deals with the utilization of vias on BGA pads. In this case, manufacturers place the vias on a circuit board’s BGA pads. Furthermore, the design has also gained wide recognition because it can reduce the space require for the vias.
What is the Significance of Vias?
Both blind and buried vias come with their unique benefits.
Power routing
These vias are useful for power and ground nets. They carry extra current. Furthermore, they are usually restricted to the larger through-hole vias.
The trace density
For boards with multiple layers, vias helps to increase the trace density. This is happening, since vias can be run over as well as beneath themselves in different directions. This vias allow the connection of different traces. This is why vias can serve as connection factors.
Signal Routing
With vias, signal routing can be enhanced in the PCBs. Majority of PCBs utilize buried or blind vias for the denser boards. In addition, microvias are appropriate for boards that are much denser.
Transmission of Signal
With vias, you can enhance the power and signal transmission present between the layers. The blind vias will transmit the signals effectively between a board’s layers. The PCB components would have to be routed on one plane if you don’t wish to integrate the vias.
What are the Considerations for Vias Creation?
Here are some considerations to take note of during the creation of PCB vias
Integrity of the signal
If the vias aren’t properly created, it could cause problems with signal integrity. For instance, the through hole via that connects the two top layers of a PCB with eight layers would have six layers of an unnecessary metal.
This unneeded metal could cause interference. This is why it is important for issues like these to be detected and solved. The via can be back drilled to remove any unused metal. Areas that are photo defined could affect the signal integrity as well.
Aspect Ratio
The thickness of the board determines the drill size that is acceptable whenever you are making use of the mechanical drills. Furthermore, there’s a limit to how the mechanical drill could penetrate before they become unreliable. Circuit board manufacturers usually demand for a 10:1 value for the aspect ratio for the drill sizes.
This aspect ratio forms a significant consideration for vias design. Furthermore, if you desire smaller holes, you may use a microvias that has a 1:1 value for aspect ratio. To get smaller holes, you need smaller aspect ratios.
Routing Density
For cases whereby you have to route the board’s dense areas, make sure the vias isn’t blocking up the return paths of the ground plane. Furthermore, this can happen under the dense parts like pin-count ball grid arrays whereby hundred vias can be found in small areas. The hole depth and outer layers can help enhance the routing density.
Plated Through Hole vs Via in a Circuit Board
Via and plated through holes are to distinct hole types utilized in PCBs. The plated through hole is a hole that is drilled into the PCB and then lined with conductive materials like copper. This lining becomes plated with metals such as gold or tin for creating a connection between the PCB layers. This method is usually used for creating electrical connection in-between the different layers of a circuit board or components present on the board
Similarly, via is a hole drilled into one PCB layer and then plated with the help of conductive materials such as copper. Vias are useful for connecting several parts of one layer of a PCB. They are also useful for connecting components present on any of the board’s sides. In addition, vias could be either microvias or through hole vias.
Conclusion
Plated through hole vs vias are utilized in PCBs to help conduct electricity. Plated through will pass through the whole board and then connect all the layers. Vias, in contrast, will connect the different components or parts on one PCB layer.
