Blog

Uncover the latest PCB innovations, expert insights, and industry trends with PCBX's comprehensive blog. Stay ahead of the curve in PCB design, manufacturing, and assembly.

Printed circuit board Blog - PCBX

PCB Resources

Your comprehensive PCB knowledge resource. Explore in-depth guides on PCB design, material selection, fabrication techniques, and industry trends. Empower your PCB expertise today! 

PCB Resources - PCB Expert Manufacturing - PCBX

PCBA Resources

PCBX: Master the art of PCB assembly. Delve into expert guides on PCB assembly processes, techniques, and quality control procedures. Elevate your PCB assembly skills now! 

PCBA Resources - PCB Expert Manufacturing - PCBX

PCB Design

The PCB Design Resource Channel is a worthwhile location that provides electronic engineers and designers with top-notch resources and tools to design printed circuit boards. In this section, the latest guides in design, tutorial videos, software tools, example projects, and best practices are organized together for reference on how best to go about optimizing the design process for better work efficiency and product quality.

PCB Design - PCB Expert Manufacturing - PCBX

What is the Difference Between Pad and Via? 

Printed Circuit Boards presently play an important role in modern electronics, enabling complicated circuits to become compact, reliable, and efficient. In the case of the Printed Circuit Boards, there are two critical elements: Pads and vias, which serve different unique and essential functions. Although they always come in a pair, they are for different functions concerning the board layout. Understanding these differences will be crucial to effective PCB design and manufacturing.<h2>What is a Pad?</h2>Pad or soldering pad is, on a PCB, an area to which the lead of a component or the terminal is to be soldered. These small exposed areas of metal form an integration point for components, land pattern - binding or positioning it, and electrical attachment to the board.<h3>Types of Pads</h3>Pin Pads: Pin pads are the kind of pads with soldering holes. They are basically utilized for through-hole components. Such components have their leads through the board to the opposite side, where they are soldered on.Surface Mount Pads: Surface mount pads do not contain soldering holes. They are used for surface mount technology components, which are soldered directly onto the pad atop the board.A Pad performs the function of mechanically and electrically securing components to the board with reliable connectivity in the circuit. <h2>What is a Via?</h2>A via, or vertical interconnect access, is a small hole drilled into the PCB for connecting traces between different layers. Vias are very important in multi-layer or double-sided boards to route signals or voltages vertically through the board in order to connect various layers.<h3>Types of Vias</h3>Plated Through-Hole (PTH) Vias:These vias run from the top layer to the bottom layer and connect all the layers in between.Blind Vias:Blind vias are those extending from an outer layer either from the top or bottom to one or more inner layers without reaching the opposite side.Buried Vias:Buried vias come totally within the inner layers of a PCB and never reach either of the outer layers.Microvias:Very tiny vias, and usually laser-drilled. Microvias are a feature of High-Density Interconnect HDI PCBs.The main function of vias, however, is to route signals across multiple layers of PCBs, hence enabling more complex and compact designs.<img src="https://img.pcbx.com/dev/file/image/article/20240916/9493aef1988f4c32934e94adbe520a38.png" alt="Pads and Vias-PCBX" data-href="" style="width: 100%;"/><h2>Key Differences Between Pads and Vias</h2>Understanding the differences between a pad and a via is indispensable for any professional dealing with the design of printed circuit boards :Function and Purpose:Pads: Represent the main soldering points for components and provide the required mechanical and electrical connections on the surface of the board.Vias: These provide electrical interconnection between different layers of the printed circuit board. They make multi-layer routing possible without using any surface area.Structural Considerations:Pads: They are meant to be mechanically strong enough to bear the severe stresses during the installation of the components and while soldering them, so that for this reason they have a sufficient diameter, to allow the lead of the component end.Vias: Smaller apertures are needed, focusing on keeping electrically joined layers together. The smaller vias sometimes may be more expensive because of precision in drilling and plating processes.Design Considerations:Pads: There is a need to ensure spacing appropriately, pad diameters, and solder mask clearance for good soldering and reliable connections.Vias: Consider thermal and electrical properties, minimize problems such as noise and reflection in signals. This is achieved by the optimal implementation of via size, its placement, and dimensions of the annular ring.<h2>Detailed Insight into Pads</h2>The size of the aperture in the Pad should be at least big enough to clear the component pin. Because the drilling process can be a bit sloppy, the aperture will, in general increase about 0.15 mm. So for example, with a designed hole diameter of 0.5mm, after drilling it could be around 0.65, so the final aperture would be approximately 0.55mm after copper immersionRegarding the Pad structure, there should be at least 0.20 mm width in the soldering ring to ensure reliable adhesion and electrical connectivity.<h2>Detailed Information on Vias</h2>Vias are involved with a high level of drilling and plating art in manufacture. Within most Chinese PCB manufacturing enterprises, the general PTH diameter is about 8 mil (0.2 mm), while BVH has a diameter of 4 mil (0.1 mm). Because of the production process, the final actual aperture of a via will be about 0.1 mm less than the size planned for it. That is to say, after the copper immersion process, a via designed to be 0.5 mm in diameter may have an actual diameter of about 0.4 mm. Usually, in order to ensure good electric connections, the soldering ring of the via should be at least 0.15 mm wide.<h3>Via-in-Pad</h3><img src="https://img.pcbx.com/dev/file/image/article/20240916/d9a58de7de524938aef79a51a8976f52.png" alt="Via-in-Pad-PCBX" data-href="" style="width: 100%;"/>In high-density PCB design, space optimization is critical, and creative routing solutions often used include via-in-pad. In via-in-pad design, vias are placed underneath the surface mount component pad. This helps to provide space on the surface for other components and can help towards better routing efficiency, thermal dissipation, and inductance reduction.However, via-in-pad designs are more challenging and more expensive. Via size is also a critical issue because larger vias can have unnecessarily high resistance. Vias need to be placed correctly to reduce noise without impacting signal integrity; annular rings should also be suitable to maintain electrical and thermal integrity. Moreover, the solder mask design too needs to be such that it prevents solder from wicking into the via itself during the assembly.<h2>Conclusion</h2>Understanding the difference between pads and vias is very important for effective PCB design. While pads are responsible for component placement and electrical connections along the board surface, vias provide interlayer connections, very important in multi-layer PCB designs.While both pads and vias are used for different purposes, appropriate design and implementation of the same are quite important for the development of reliable and high-performance PCBs. From simple single-layer boards to complex multilayer designs, recognizing and appropriately using the respective functions of pads and vias will do much good in efficiency and functionality for your electronic project.By mastering these aspects, PCB designers can make well-informed choices that optimize both the design and manufacturability of their boards, ensuring robust performance and cost-effective production.

Pads and vias are crucial for PCB design: pads serve as soldering points for components, while vias connect different layers. Understanding and correctly implementing them ensures reliable, efficient, high-performance PCBs.

What is the Difference Between Pad and Via in the PCB? 

In this dynamic world of electronics, everything electronic has in its heart a printed circuit board. From your smartphones, computers, and industrial machinery down to some of your modern household appliances, PCBs form the backbone in today's gadgets. In designing and manufacturing PCBs, one needs to know and understand several types of holes and vias that are common features of every PCB. While the terms "holes" and "vias" may sound somewhat synonymous, they do hold different purposes and specific characteristics critical to the performance and functionality of a PCB. This article will elaborate on the differences between PCB holes and vias with in-depth information about their function, types, construction, and usage in PCB design.<h2>PCB Holes</h2>A "PCB hole" generically refers to any opening drilled into the PCB substrate. Holes in PCBs may serve either electrical or mechanical purposes. Holes represent an integral part of the structure and functionality of a board, accommodating components and hardware.<h3>Types of PCB Holes</h3><h4>1. Through-Hole</h4>Description: Thru-holes are completely drilled openings running from one side of the PCB to the other. These usually serve for Thru-hole technology components-resistors, capacitors, and integrated circuits with wire leads through the PCB-soldered on the opposite side.Purpose:Component Mounting: Essentially, the thru-holes are used for mounting and fastening electronic components with extended leads through the PCB.Electrical Connectivity: Although basically mechanical, through-holes provide electrical connectivity when the component leads are soldered to the copper pads on the PCB.<h4>2. Mounting Hole</h4>Description: Mounting holes are normally non-plated holes used for mechanical purposes. They allow no electrical connections but are very important in holding the PCB within its enclosure or mounting it onto some other structure.Purpose:Mechanical Attachment: It is used to screw down screws, stand-offs, or other hardware meant for mechanical attachment in place.Isolation: It sometimes provides isolation between different sections in a multi-board assembly.<h3>Construction and Considerations</h3>Drilling Process: The application of holes in a PCB involves a precision drilling process where the PCB undergoes drilling before additional manufacturing steps for it may be performed, such as layering and plating.Plating: Based on requirement, some holes would be plated with copper for good solder adhesion and mechanical stability, and others without plating.Design Considerations: Addition of holes impacts on routing and space in a PCB. A designer has to very carefully place the holes so as not to interfere with signal paths and other components.<h2>Vias</h2>A via is another special kind of hole that is designed specifically for electrical connections between different layers of a multilayer printed circuit board. Unlike regular holes, vias are always made with a copper plating to ensure the best electrical paths.<img src="https://img.pcbx.com/dev/file/image/article/20240911/195ff9f2966e44bbb2cd9f2fd6f3526f.png" alt="PCB Vias-PCBX" data-href="" style="width: 100%;"/><h3>Types of Vias</h3><h4>1. Through-Hole Via</h4>These vias are the ones that go through the whole PCB from top layer to bottom. They connect all the layers they go through.Purpose:Layer-to-Layer Connectivity: It provides electrical connectivity between disparate layers in a multi-layer Printed Circuit Board that enables complex circuitries.Usage: They are used very frequently in tracking signals, power, and grounds across layers.<h4>2. Blind Via</h4>Blind vias connect an outer layer with one or more inner layers without reaching all the way through the PCB.Purpose:Space Efficiency: Since the via is required to occupy only those layers which are really necessary, it saves more surface area of the PCB for component placement and routing.Reduced Complexity: Due to the via depth limitation, it reduces the complexity in managing signal integrity by reducing stray capacitance.<h4>3. Buried Via</h4>There are some vias that connect only the internal layers of the PCB without going to the outer layers.Purpose:Complex Routing: It allows for complex internal layer routing without hampering surface layers for high-density and complex PCB design.Signal Integrity: The signal and power integrity is maintained by managing the internal layer connections through them effectively.<h3>Construction and Considerations</h3>The vias are first drilled and then copper-plated for good electrical conductivity. For microvias, HDI PCBs use advanced manufacturing techniques such as laser drilling.Parasitics and Signal Integrity: Vias add some parasitic inductance and capacitance to the overall circuitry. These may weaken the performance of high-speed signals. Such issues must be taken into consideration during the design process for very high-frequency and high-speed PCB designs.Design Implications: There are strong influences on the performance of a PCB based on via placement and type. Adequate via management should be carried out to ensure that no problems in signal integrity, thermal issues, or added manufacturing costs arise.<h2>Comparing PCB Holes and Vias</h2><h3>Functional Differences</h3>Mechanical vs. Electrical:PCB Holes: Those are mainly for mechanical mounting when they constitute mounting holes and electrical/machine when they are for through-hole components.Vias: Vias are used strictly for electrical connectivity between the different layers of the Printed Circuit Board.Design and Layout:PCB Holes: Placement is to a great extent decided by component and assembly requirements.Vias: Placement is one of the prime considerations in the electrical design. It will affect not only signal routing but also impedance control and even thermal management.<h3>Construction and Manufacturing</h3>Drilling Techniques:PCB Holes: Generally drilled using mechanical drills. The processing technique is simpler but needs precision to achieve the proper positioning.Vias: Often utilize advanced techniques such as laser drilling, especially when microvias are used in HDI boards.Plating:PCB Holes: Either plated or unplated depending on the function.Vias: Always plated for the electrical connectivity across layers.<img src="https://img.pcbx.com/dev/file/image/article/20240806/0660d36a01684a4f8babff1b8baae323.jpg" alt="PCB Holes-PCBX" data-href="" style="width: 100%;"/><h3>Design Implications</h3>Routing and Space Utilization:PCB Holes: Affect the available space for routing other traces or placing more components.Vias: Affect the routing strategy and stack-up design. Efficient via management has the potential to make profound improvements in the performance of the PCB.Thermal Management:PCB Holes: Through-plated holes can aid in thermal management by allowing heat to dissipate through the board.Vias: Thermal vias are designed to channel heat away from critical components toward heat sinks or dissipation areas.<h2>Conclusion</h2>First of all, to effectively and reliably design printed circuit boards, one should understand the difference between PCB holes and vias. Though both are integral components with respect to the functionality of the PCB, they serve different purposes: whereas PCB holes are important with regard to mechanical stability and component placement, vias are about providing critical electrical pathways between layers. An effective PCB design exploits these two in the best way to yield the optimal performance, reliability, and manufacturability of the board.Whether you're an experienced PCB designer or you're just entering this area, being able to appreciate the nuisances of holes and vias will surely enhance your design capability and result in better electronic products. In the competitive world of electronics, the devil is always in the details, as knowing these sometimes minor differences makes all the difference in the success of your projects.

PCBs are central to electronic devices, featuring holes and vias critical for functionality. Holes, like through-holes and mounting holes, serve electrical or mechanical purposes, while vias ensure electrical connections across PCB layers. Understanding their differences is key for optimal performance, reliability, and manufacturability in PCB design.


What is a PCB Hole and Via Difference?

The term "via" is very wide and is an integral part of electrical engineering in the design process of multi-layer Printed Circuit Boards or simply, PCB. From the Latin word for "way", the "via" makes a very critical contribution to the functionality of PCBs, allowing for the transfer of electrical signals across different layers. Notably, the concept of a via can be obscure to many. This article will try to rid this ambiguity by exploring what a PCB via is, how it works, its types, and the processes involved in covering it.<h2>What is a Via?</h2>The simplest form of a via is just a small, drilled hole passing through two or more adjacent layers of a multi-layer PCB. These drilled holes allow the passage of electrical signals and power between the layers, thus making it possible that complex pathways within a circuit are possible. Since various layers of a multi-layer PCB are relatively independent, vias play a significant role in interlayer interconnects.Vias can be broadly categorized into three types based on their functionality—blind via, buried via, and through-hole via.<h2>Functions of Via</h2>The major purpose of vias within a PCB is to create an electrical path between the different layers on the board. Normally, there are several layers in a PCB so that such an intense network of traces and components can be accommodated. Vias allow the flow of electrical signals and power between layers; this is a way of making different components and portions of the circuit interconnected in an efficient manner.Here is how some of the important roles of vias are played in PCBs:Inter-Layer Connectivity: The via, on its part, allows signals and power to travel to other layers in the PCB.Inter-Layer Connections: Vias enable the conduction of signals and power to other layers of the PCB, connecting traces and components on one layer to another. It becomes critical for multilayer PCBs when, most of the time, there is no space left or it's impossible to route on surface layers only.Component Interconnection: Vias are important for interconnecting components across different layers of PCBs. This is especially required when compact, closely packed circuits require the space in which to mount components to be very close.Efficiency in Routing Signals: Via allows the routing efficiency. If there would have been no vias, the traces would have had to snake through the surface layers, wasting even more space, and probably interfering with signals. Vias allow routing signals through a PCB much more directly and with good space saved.It plays an important role in **Power Distribution**: Vias may also be used in the interconnection of different-layer powers to planes that distribute power to various components along the board.Minimizing Signal Distortion: In high frequency and high-speed applications, beyond doubt the vias will affect the signal integrity; therefore, good design and placement of vias can minimize signal distortion. Reflections and impedance mismatch problems that will raise the performance of the PCB.Utilization of Space: Vias make space utilization possible on a PCB because they can be used in multi-layer designs and would eventually prove to be good for routing activities, ensuring that the conduction would be done right. This applies to modern small and compact electronic gadgets.High-Density Interconnect: Microvias are parts of advanced PCB designs for fine pitch designs that ensure the gadgets get miniaturized further with the use of HDI technology.In this regard, vias form the most vital components in PCB design, acting as the carrier for electrical linkage among its layers, thus contributing to efficiency, reliability, and compactness of electronic circuits. Design and placement of these elements are thus very critical in various applications.<h3>Types of Vias</h3><img src="https://img.pcbx.com/dev/file/image/article/20240911/195ff9f2966e44bbb2cd9f2fd6f3526f.png" alt="PCB vias-PCBX" data-href="" style="width: 100%;"/>Blind ViaThe blind via is a small hole that starts from one surface of the PCB, but doesn't pass all the way through to the other side. One of the main advantages of blind vias is that they occupy no real estate on all the layers. It gives extra room to increase design density, particularly in small designs. And for that matter, they are often applied in high-bundle-density circuit packs like ball grid arrays and high-density interconnect PCBs. Buried ViaBuried vias are connections involving at least two inner layers but not reaching the outer layers, and hence they can't be seen from the outside. It is this aspect of invisibility that makes them quite effective in reducing electromagnetic interference &nbsp;between the signals, thus improving the reliability and performance of the PCB as a whole. Buried vias are quite important in HDI PCBs, where space is at a premium and signal integrity needs to be maintained.Through-Hole ViaThe most common variant used in the manufacture of PCBs is the through-hole via. It is a hole passing throughout the PCB, somehow interconnecting the inner and the outer layers in a very straightforward way. Through-hole vias mostly find applications in internal board interconnections; however, they can act as mounting holes for different components. Because they are rather simple to be manufactured, through-hole vias find broad application in a surprisingly large range of designs for PCBs.<h2>Covering Vias</h2>PCB vias can be covered or finished using three methods: tenting of vias, vias not covered, and plugged vias with solder mask.Tenting Vias<img src="https://img.pcbx.com/dev/file/image/article/20240911/9ee427346aa44ba58beccbe95664a4d7.png" alt="Tenting Vias-PCBX" data-href="" style="width: 100%;"/>Tenting vias involves covering the annular ring, the visible part of the ring surrounding the via hole, with a solder mask for insulation. This solder mask forms a protective layer to prevent any type of accidental electrical connections. For insulation to be proper, the annular ring must be entirely covered with a thick enough solder mask to prevent the chances of an accidental short circuit.Vias Not Covered<img src="https://img.pcbx.com/dev/file/image/article/20240911/5c488c7f64c34e7cb2855b42abd77ca7.png" alt="Vias Not Covered-PCBX" data-href="" style="width: 100%;"/>If the vias are left uncovered, it mostly leads to the hole and the annular ring being exposed. This may actually be of potential benefit in debugging, as access to measurement signals is easier with an exposed probe point. More importantly, it helps in heat radiation from the board by increasing the exposed surface area. The downside is increased risk of short circuits due to exposed conductive parts.Plugged vias with solder mask fill the via holes with some kind of solder mask, which in turn closes the via. This will avoid the generation of solder balls in the wave soldering process and avoid flux residue inside the via hole. Therefore, this method is often used to design PCBs that incorporate BGA or IC assemblies. This process seals the vias to ensure far more safety and efficiency during the manufacturing and operational phase.<h2>How to Select the Right Via?</h2>The choice of via type depends on the needs of the PCB design. Blind and buried vias offer space-saving and a higher signal integrity, but they are only possible on boards containing four or more layers, and they are considerably more complicated and expensive to produce. On the other hand, through-hole vias are simpler and less costly, so they normally find preference in standard designs for PCBs.<h2>Conclusion</h2>Knowing what a Via is and how it works is the bottom line of PCB design and manufacturing. Vias—blind, buried, and through-hole—are the critical paths used to connect complex multi-layered boards. The vias are covered with different methods: tented, with photoimageable solder mask, or plugging. These differ in meeting the various needs to raise the efficiency, reliability, and functionality of today's PCBs.The nuance of via design and application becomes ever critical to both engineers and manufacturers as compact and high-performance printed circuit boards &nbsp;continue to rise in demand. If the designers choose the right vias and covering methods, they shall be able to compose advanced, reliable, and highly functional PCBs.

Vias—blind, buried, and through-hole—are essential in multi-layer PCBs, enabling signal and power transfer between layers. Covering techniques like tenting and plugging with solder masks enhance PCB reliability and performance, crucial for compact designs.

What is a Via in PCB?

Printed Circuit Boards Glossary and Terminology

Dive into our PCB glossary to master the key terms and definitions essential for efficient design and production, ensuring your projects run smoothly and effectively.