Via tenting is an important step in printed circuit board construction. When should it be used? And what exactly makes it an important step? Some individuals shared their thoughts on the value of via tenting. Keep reading to learn more about this process from them.
David Smith

David Smith

Co-Founder at .

Protect the Vias From Damage and Contamination

Via tenting is the process of covering vias on a printed circuit board (PCB) with a layer of solder mask. This process is important in PCB construction because it helps to protect the vias from damage and contamination, which can lead to electrical shorts. It also helps to reduce the risk of electrostatic discharge (ESD) and crosstalk between components.

Additionally, via tenting helps to ensure that components are properly soldered and that the board is free from defects. In terms of when to use via tenting, it is generally recommended for any PCBs that will be exposed to environmental factors, such as moisture or dust. It is also recommended for any PCBs that will be used in high-frequency or high-power applications, as the additional layer of protection can help to reduce interference. Additionally, via tenting is often used for aesthetic purposes, as it can help to make the PCB look more professional.

Provide Resistance to Oxidation and Corrosion

Vias are important in PCB assembly and design because they act as conductive holes that connect layers, allowing for more components and better heat displacement. Installing vias is not as simple as drilling through the substrate, and planning is dependent on the board’s specifications. Some boards need normal vias, whereas others necessitate via tenting. Choosing the appropriate vias is dependent on the individual board and its requirements.

Tented vias on a PCB provide various design advantages, including resistance to oxidation and corrosion, which are frequent difficulties caused by ambient moisture. Because these vias are not exposed to moisture, they are less prone to suffer from these problems. The most effective technique of protection is to cover the board for frequent cleaning. Copper exposure can cause current interruption and physical damage to the board, resulting in unfixable problems such as warping in the substrate.

Tented vias are also resistant to corrosion and debris, which can cause circuit shorts and other physical damage. While some boards may necessitate the use of non-conductive material to plug exposed vias, tenting is a less expensive solution due to the less materials required, making it a cost-effective choice in PCB assembly.

Tenting vias are required in some PCB designs to meet DFA reliability criteria, making them important for the manufacturing process. Tenting is an excellent addition in circumstances where it is not required for a variety of reasons, including:

    ● Environmental Protection: For PCB installations in industries with moisture or corrosive atmospheres, such as pool, dock, boat, drilling, mining, and scientific/medical equipment, through tenting is advised. The size of the vias on the board influences whether or not via tenting is possible. Tenting is often utilized with boards with hole diameters smaller than 12mm, because larger holes require more solder mask solution, which decreases as hole size grows. A PCBA manufacturer can assist in determining the best mask solution for the project.

    ● Stop Solder Wicking: Solder wicking occurs when beads or drips of solder migrate away from solder pads, resulting in shorts and current flow problems. Wicking solder can become lodged in the through hole of a via, shorting or blocking it. Tenting vias to avoid solder wicking is advised when dealing with smaller PCBs, since it eliminates circuit disturbance and reduces onboard space utilization. This option, however, is not accessible for bigger boards or machines.

Matt Kerr

Matt Kerr

Machine Learning Engineer and the Founder of .
Mirna Vuksan

Mirna Vuksan

Head of Marketing at .

For Thermal Management and Electric Isolation

Via tenting is an important aspect of printed circuit board (PCB) construction that involves covering the vias with a layer of solder mask or other protective material. This technique provides several benefits and is typically used in specific situations.

The primary importance of via tenting is to prevent the ingress of contaminants, such as dust, moisture, and flux residue, into the vias during PCB assembly and subsequent operation. By covering the via holes, tenting reduces the risk of short circuits, corrosion, and other issues that may arise due to the presence of foreign substances.

Here are some key reasons for using via tenting:

    1. Electrical Isolation: Tenting ensures that there is no direct electrical contact between the via and any nearby conductive elements, such as traces or copper pours. This can be crucial when dealing with high-frequency signals, sensitive analog circuits, or when isolation is required for design or safety reasons.

    2. Thermal Management: Tenting helps in thermal management by minimizing the impact of air gaps around the vias. By covering the vias, the heat dissipation can be more controlled and predictable, preventing hot spots and enhancing overall thermal performance.

    3. Solderability: Vias that are left open can potentially trap air and flux residues during the soldering process, leading to poor solder joints or incomplete filling. Via tenting helps maintain a consistent soldering surface, ensuring reliable solder connections.

    4. Mechanical Protection: The tenting layer adds structural integrity to the PCB, protecting the vias from physical damage, such as accidental scratches, abrasions, or impacts during handling, assembly, or operation.

It is important to note that via tenting is not always necessary or appropriate for every PCB design. In certain cases, such as when thermal vias are intended to dissipate heat, or for specific testing or debugging purposes, leaving the vias open may be preferred. The decision to use via tenting should be based on the specific requirements of the design, including electrical, thermal, and mechanical considerations.

It is recommended to consult with your PCB manufacturer or design guidelines to determine the best approach for via tenting based on your specific project requirements and constraints.

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