Vias, Aspect Ratio and their Importance for the Printed Circuit Boards Manufacturers


A good and reliable PCB Manufacturer is always in search of doing something challenging, after all, accomplishing the almost impossible offers a certain level of gratification. In addition, it is imperative for the cheap Chinese PCB Manufacturer is to adopt the changing technology in order to stay afloat.


Since Printed Circuit Boards play an integral part in any electronics, thus they need to be updated with the changing technological trends and consumer demands. Over the years, we have seen tremendous growth in terms of technical advancement and speed of Printed Circuit Boards. To further, enhance the capabilities of PCB, we now have the aspect ratios.

If your objective is to create simple Printed Circuit Boards, you do not have to pay much heed to the Vias, or aspect ratio. However, if you plan to deliver multi-layered Printed Circuit boards, both these concepts hold great importance.

Not only manufacturers embarking on the manufacturing journey of post Printed Circuit Design, take on the challenge of using the Vias throughout their design. Despite the advantages this technology offers, we come across manufacturers who are reluctant to incorporate it mainly because of the challenges that it offers.  However, the aspect ratio is inevitable for multi-layered PCBs, and an efficient manufacturer will ensure to use this concept.

Complete understanding of the PCB concepts will help you choose the right PCB Manufacturer; therefore, we will be discussing the following:


Read More about: Choosing Best PCB manufacturers


Table of Content

  • What are Vias and its Different Types?
  • Vias before Aspect Ratio for Printed Circuit Board
  • Importance of Vias for Printed Circuit Board Design
  • Aspect Ratio of Printed Circuit Boards
  • Significance of Aspect Ratio for PCB Manufacturer
  • Summary


What are Vias for Printed Circuit Boards and Its different Types?


printed circuit board


Before we get down to the Aspect Ratio, it is important to understand what Printed Circuit Board vias. We also need to focus on their importance for PCB manufacturing.

A Printed Circuit Board has drilled holes, Vias, through its traces. The sole purpose of Vias is to form a connection between traces of different layers. Mostly, the Vias are present in HDI Multi-layered PCB mainly because it connects every layer in one way or another.

There are different types of vias, and they offer different functionalities. Below are the common types of Vias:


Plating Through Hole (PTH)


“Planting Through Hole” or better known as PTH is among the most common types of vias. It is a hole dug completely through a multiple layers PCB. The via does not require a lot of effort and it is cost-efficient, however, it tends to take up a lot of space on the Printed Circuit Board. Thus, the PCB Manufacturer has very little space left for all the other components of the chipboard.


Blind Via Hole


In order to connect the exterior most circuit with the inner layer that is present just right below it, the manufacturer uses the Blind Via Hole technique. It is perhaps difficult to drill as the person needs to be extremely attentive to the depth of the hole being created at the time of Bling Via Hole's construction.


Buried Via Hole


Buried via Hole or Hidden Via, is a tricky, yet effective technique. You will see them mostly in High-Density Interconnect (HDI) Printed Circuit Boards. With buried Via Hole, it is possible to connect any internal layers of a multi-layered PCB. However, you will not be able to see it from the exterior, as it does not touch the outermost layer. The above is achieved by incorporating the bonding post-drilling approach.

The High-Density Interconnect Printed Circuit Boards have dense construction and they require extremely small components that are put together. There is a very short distance between each component. Since Buried Via holes tend to increase the component holding capacity, therefore they are PCB Manufacturer’s first choice when it comes to designing and developing HDI PCBs.

To circuit board completely encapsulate the buried Via. Since they are completely covered, thus you are not able to see them. Mirco-Vias are usually the top priority for HDI Printed Circuit Boards, as they allow holes with an extremely small diameter. To ensure the seamless connection of these holes to the out layer of the pad, PCB Manufacturer applies a conducting material on them.


Tented Vias


In order to keep the exposed conductive pads to a minimum on a PCB, the manufacturer, use Tented vias. They cover the vias with a solder mask. Tented Vias reduce the chance of shock occurrence during the solder bridging in the PCB assembly process.

Initially, cheap PCB Manufacturer used liquid photo imageable (LPI) solder masks for the tenting process, however, they had to become up with something better as the LPI technique lacked consistency. Most Vias ended up getting damaged and some partly broken.

Therefore, to overcome these problems PCB designers had to look towards better and more refined methods. They started plugging the Vias using either non-conductive or conductive material before they went on tenting with the LPI solder mask.


Importance of Vias for Printed Circuit Boards Design


If the manufacturer plans to design a simple Printed Circuit Board, then he does not have to pay heed to the Vias. However, if the manufacturer plans to develop a complex, multi-layered Vias, then it is imperative to use Vias.

Lack of via will force the manufacturer to route everything on a single panel. Vias have the capability to form a connection between the layers, thus allowing signals and powers to travel across the chip. It is nearly impossible to route all components on a single panel in a multi-layered printed circuit board because of surface-mounted components.

If the manufacturers do not use vias, they end up facing a lot of challenges in the routing process. In addition, things become extremely difficult with the multi-layered printed circuit board ranging from component placing, connectors, and BGAs.

The manufacturer enjoys a decent density of components because of via especially in case of Multi-Layered Printed Circuit board.

Vias allows running traces over and under each other in opposite directions across layers. It is possible to connect traces of different layers with each one through Vias. In addition, you can enjoy the vertical connection element as well.


Aspect Ratio of Printed Circuit Boards


printed circuit board

In simple words, we can say that the Aspect Ratio of a Printed Circuit board is the ratio between the diameter of the Vias that you drill and the thickness of the board. The aspect ratio has a direct impact on the trace placement of the Printed Circuit board.

For example, if you have a Printed Circuit Board with 0.3” of thickness and your drill vias with 0.03” of diameter, what will be the aspect ratio? The answer is simple, it will be 10:1. The increase in the aspect ratio will increase the plating surrounding the vias in comparison to the inside drilled portion.

This can lead to earlier cracking mainly because of the z-axis expansion during soldering. To have consistent plating throughout the via, we suggest you use a low aspect ratio. In addition, a low PCB aspect ratio will offer greater strength throughout the lifespan of the Printed Circuit Board.

Some of the best, yet cheap Chinese PCB Manufacturer are able to attain an aspect ratio of 6:1. It means that the board incorporates the smallest practical drilling diameter of somewhat 0.013”. The maximum board thickness is around 0.078”.

So, to ensure that as a manufacturer, you do not face any problem in the long run, we recommend that you keep both the smallest drill diameter and the board thickness in mind, especially, if you plan to achieve an extremely low aspect ratio. In addition, the vias will be strong and they will offer you a better connection to mount the component onto them.


Annular Rings


Now that we are done with incorporating the vias correctly into the Printed Circuit board, next, we need to focus on drilling through the via location. So, we will now focus on Annular rings. They are rings made of copper that the manufacturer place around the drilled area of the via.

This drilled area is responsible for giving us the connective surface in which we can either pill in to have nicely plated via or we can mount components. The size of the annular ring has a direct impact on the size of the connection area. If you want a big connection area, you need to have a large annular ring and vice versa.


Conventional Print Circuit Board Aspect Ratio


Currently, the conventional Printed Circuit Board aspect ratio in the industry is 8:1 (PTH). If the thickness of the board is 0.2mm, then you need to have a minimum PTH around 0.25mm


 Defining Via Requirements


In order to enjoy the seamless functionality of Printed circuit boards, you need to have clear and precise requirements. Make sure to clearly, incorporate the type and the treatment in the fabrication documentation, as this will help you achieve your goal effectively.

To increase clarity, you should have a separate file for each set of the vias that you use in the Printed Circuit Board.


Information Required for TYPE


  1. Pair of layers that you plan to connect via drill, buried, blind or any other.
  2. The tolerance, usually it is +/-0.004”, however, vias that are either extremely small or unplugged, they can have around +000/-hole diameter.
  3. The diameter of Via
  4. The type of Via: Buried, Thorough, Blint, Tented
  5. Example: Drill a via with 0.009”, from Top layer one to Ground layer two. It has a finish of 0.008”+ 0.000/-0.008”.


Information Required for TREATMENT


  1. Process all ______ vias diameter with solder mask incorporating onto the pad. However, it does not include the filling hole per Gerber file (NAME).
  2. One-Hundred Percent Fill: Plug Via: We plan to use IPC Type 5 treatment for all _______ Diameter vias in addition to using non-conductive expoxy.
  3. Partial Fill: Plug Vias: We plan to use either the IPC Type 4 treatment or the Button for all _______ Diameter vias in addition to using non-conductive expoxy.
  4. Cap and fill all _____ diameter vias as per IPC Type VII. Fill the hole with planarize, non-conductive expoxy, and plate over. Finally, go to applying the surface finish over the pad.


Significance of Aspect Ratio for PCB Manufacturer


We already know that the plated holes tend to be divided into  holes and buried or blind vias, depending upon the design of the PCB Manufacturer. These holes are considered the sole of the entire Printed Circuit board layout along with the panel points of different board layers.

The thickness of the Printed Circuit Board has a direct impact on the size of the hole, the thick a PCB is, the smaller the hole will be. In addition, the flow of platting solution via these holes becomes challenging and complicated.

Thick PCB also results in a lack of uniformity in terms of plating the center areas of the holes. Thus, plating becomes a troublesome task, if you plan to have a higher aspect ratio. We did not say, you could achieve, higher aspect ratio, you can. However, you will need advance and state of the art equipment, a refined and well-established manufacturing process in order to achieve reliable plating.


King PCB Manufacturers


At KingPCB Manufacturer, we allow our clients to choose from different thickness and minimum sizes of the hole. Below is one example of the aspect ratio capabilities we offer our clients.

Board Thickness Min. Hole Size
93” 9”
80” 8”
8”-62” 6”
125” 12”

This is one example, if you want something more or less, our knowledgeable and experienced staff will accommodate you. As one of the leading PCB Manufacturers, we tend to deliver only the highest quality possible. We ensure that our products are according to the general standards of the PCB industry.

We promise to deliver high quality Printed Circuit boards at competitive prices. In addition, we have the capability to carter order of different sizes while ensuring timely deliver and quality. We will never compromise on the quality, and we have a list of clients to vouch for us. Our physical production unit is what makes us different from several online PCB Brokers, thus we have complete control on the quality.

To ensure smooth and outstanding experience, we are available around the clock. Our outstanding customer care services allow us to resolve our client’s problem within minutes. Plus, we have a support group intact that can deal with all your technical problems in minimal time.




Printed Circuit boards hold a great importance and they have a direct impact on the functionality of the electronics. Therefore, it is imperative to have only the highest quality PCBs. You need to pay close heed to Vias and aspect ratio as both these factors play an important in defining the quality of the Printed Circuit board.

You can have a quality simple PCB with Via, however, for Multi-Layered PCB you need to incorporate Vias. It is extremely difficult to create high quality and reliable multi-layered printed circuit boards with Vias. Likewise, aspect ratio also holds great importance for effective Printed Circuit Boards.  Therefore, all the PCB Manufacturers should take aspect ratio seriously.

When manufacturer does not play close heed to the aspect ratio, they end up with tattered circuit boards that are barely able to form a connection between points via plating. This can even lead to a bad connection between the electronic component placements. Manufacturers around the globe tend to use Vias and the right aspect ratio in order to come up with high quality Printed Circuit Boards.


By hqt