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3 main types of via on flex PCB

Writer's picture: Flex Plus Tech teamFlex Plus Tech team

Updated: Dec 25, 2024

Flex PCB is the thin circuit board that is commonly seen in our electronic devices. And vias play a very important role in Flexible PCB. In flexible circuit board manufacturing, The type and quality of vias affect flexible PCB price, especially in batch orders. Next, let’s take a closer look at what via is and the differences between the three types of vias.

via on flex pcb, flexible pcb via

What is a flex PCB via?

Did you know that FPC is sometimes multi-layered, just like building a building, stacked up layer by layer? At this time, the vias are like a channel built between different floors, allowing the current to run smoothly from one floor to another, and realizing the line connection between different floors.

Imagine that if FPC is compared to a building, then each layer of circuits is like a room in the building, and the vias are the elevators or stairs connecting these rooms. Without it, the current can only run around on the same floor and cannot reach other floors.

The production of vias is also very particular. First, a hole must be accurately punched on the FPC, and then a layer of conductive material, usually copper, is plated in the hole. In this way, the current can pass through this hole and smoothly transmit from one layer of circuits to another.

In short, the vias on FPC are like key "channels" that allow current to shuttle freely between multi-layer circuit boards. Sometimes it is so small that it is almost invisible, but it is an indispensable part of the entire circuit system.

When selecting a flexible PCB, via size and placement become key factors. Different types of flex pcb via serve different purposes, which is why there can be significant variations in flexible PCB prices in the market.


The 3 Main Types of Flex PCB via

There are 3 main types of vias used in flex PCB manufacturing: through-hole via, blind via, and buried via. Each has its own advantages and challenges, and the choice impacts both production complexity and pricing.

3 main types of vias on flex pcb, FPCB via

1. Through-Hole Via

Through-hole via is the most common type. They pass through all layers of the printed circuit board, connecting the top and bottom, and sometimes multiple internal layers. This is a straightforward design that is cost-effective to produce, making it ideal for lower-cost applications. Flexible PCB manufacturers often use through-hole via for bulk production orders, keeping costs low.

 

However, through-hole via takes up more space on the board, which can limit the potential for high-density designs. For applications requiring more complex, multi-layer flexible boards, blind or buried via might be a better choice.

 

2. Blind Via

Blind via only connect an outer layer to one or more internal layers, without passing through the entire board. This design optimizes space by allowing for higher routing density, which is critical for complex, multi-layer boards.

Blinds via are more expensive to manufacture due to their complexity. However, the enhanced performance and space-saving benefits make them ideal for high-end devices like smartphones. If you're looking for a flexible PCB with a compact design and better performance, blind via may be the right option despite their higher price.

 

3. Buried Via

Buried via are located entirely within the internal layers of the PCB and do not connect to the outer layers. This allows for even denser layouts and improved signal integrity in high-layer-count designs.

 

Buried via requires a highly complex manufacturing process, which significantly increases costs. They're typically used in advanced applications, such as aerospace or military electronics, where performance is critical. If you're seeking the best flexible PCBs, Buried Via offers the best reliability but comes with a premium price.

 

Through-Hole vs Blind Via vs Buried Via: Which is Best?

In flexible PCB production, different via technologies influence manufacturing costs. More complex vias like blind and buried types take longer to produce and require higher precision, driving up costs.Each type of via has its strengths, depending on your project’s needs:

  • Through-Hole Via: Best for low-cost, high-volume production; simple to manufacture and widely used for flexible PCB wholesale orders.

  • Blind Via: Ideal for high-density designs; provides better performance but comes at a higher cost.

  • Buried Via: Used for high-performance, multi-layer boards where signal integrity and space efficiency are critical; the most expensive option.

 

Choosing the right via type will impact both the performance and cost of your flexible PCB. Understanding these differences will help you make the best decision for your project.

Through hole via on flex pcb

How to Evaluate the Quality of Vias

Evaluating via quality is crucial for ensuring the performance and durability of a flexible PCB. Here are some key factors to consider:

1. Size and Consistency  

Ensure the holes are of the correct size and consistently match the design specifications. Inconsistent sizes can cause signal transmission issues.

2. Plating Uniformity  

The conductive plating on the hole walls must be even. Thin or uneven plating can lead to poor electrical connections or even failure. 

3. Smoothness of Hole Walls  

Rough or irregular surfaces inside the holes can disrupt signals or weaken the structure. A smooth finish ensures better signal transmission and mechanical strength.

4. Electrical Performance  

Conduct tests to ensure the vias perform well electrically. Any issues with resistance or continuity may indicate poor quality. 

5. Durability and Strength  

The vias should withstand mechanical stress, especially on flexible boards. Testing for durability through bending or stress tests ensures that the vias won’t fail under pressure.

 

By following these guidelines, you can confidently assess the quality of vias in flexible PCBs and ensure they meet your project's needs.

through hole via on flex pcb

 

In summary, FPC vias play a vital role in multi-layer circuit board design, ensuring that signals and currents between different layers can be transmitted efficiently and stably. Designing and manufacturing high-quality vias requires not only sophisticated engineering technology but also a deep understanding of materials and strict quality control.


In Flex Plus, we have an experienced R&D team and a strict quality control system. Choosing us means choosing professional technical support and excellent product quality. We are committed to providing customers with the best quality Flex PCB solutions to help your products achieve optimal performance. Looking forward to working with you!

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