One-stop PCB assembly tailored to your business

  • Through-hole assembly and wave soldering
  • Manual soldering available
  • SMT assembly + PTH assembly
  • PCB fabrication and PCB parts sourcing
  • ISO9001:2015 Certified & UL Listed
  • 100% In-circuit test, functional test, AOI & visual inspection

What is Through Hole PCB assembly?

Through-hole PCB assembly is a method of assembling electronic components onto a PCB. Through-hole components are those that use metal leads or pins that are inserted into holes drilled into the board. Through-hole assembly utilizes manual labour and is typically used to assemble more significant, heavier components with higher pin counts.

In addition, it allows for more reliable connections on the board, as it requires components to be soldered or crimped into place. Through-hole PCB assembly is also more tolerant of physical stress and vibration than other assemblies. By the way, Viasion provides high-quality through-hole PCB assembly, which is often used in industrial and commercial applications where reliability and durability are paramount.

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    Viasion’s Advantage As A Through Hole PCB Assembly Manufacturer

    Professional Staff

    Viasion has a group of experienced technical management personnel and efficient and professional business staff. There is also a strict testing system, fine quality management, and a perfect pre-sales and after-sales service system in Viasion.

    Excellent Quality

    With the support of high-quality PCBs, electronic components and materials and advanced PCB assembly equipment, we can guarantee to provide our customers with excellent quality products, competitive prices, and prompt delivery of products.

    Great Customer Service

    Viasion fully engages with customers at the early stage of sales to provide them with total product solutions and help them grasp every important aspect of success. We value listening to our customers’ voices and are committed to building win-win long-term relationships.

    Good Overall Customer Satisfaction

    We will try our best to provide the best products, solutions, and services to our customers. Improving customer satisfaction is the guiding principle of our work, from aspects including quality, price, lead time, and pre or after-sales services. 

    How to Order Through Hole PCB Assembly Services

    Please email our sales staff if you want to order through hole PCB assembly services. Their contact information (phone number & email address) is on our official website: We will reply to you as soon as possible. We will offer you high-quality through-hole PCB assembly services with competitive pricing. Therefore, you are welcome to order through-hole PCB assembly services in Viasion.

    We are looking forward to serving you!

    Features of Through Hole PCB Assembly

    • Through-hole PCB assembly allows components to be directly connected through drilled holes and soldered on both sides of the circuit board.
    • Through-hole technology is suitable for producing complex, large-scale circuits in high-frequency applications.
    • Through-hole components can handle heavy current loads due to their larger size and more reliable connection points than surface mount boards (SMT).
    • Through-hole PCBs are able to support heavier components such as connectors, potentiometers, switches etc., which are typically not compatible with SMT assemblies.
    • Through-hole boards have more excellent heat dissipation capabilities compared to SMT's as they allow a greater area of contact between the component and circuit board via metal plating or soldering techniques.
    • Through-hole technology offers better electrical performance in terms of signal integrity, EMI shielding & ground plane designs when compared with other technologies like SMD/SMT.
    • Through-hole boards offer easier repairability than surface mount technology because they give both sides easy access for rework and repairs.
    • Through-hole technology offers more excellent reliability than surface mount technology due to its robust mechanical connections. Therefore, it is ideal for applications where maintaining a secure connection is paramount.
    • Through-hole boards have greater tolerance of temperature, shock and vibration than SMT due to their larger size and strength of electrical connections, making them ideal for applications where these parameters are essential.

    Advantages of Through Hole PCB Assembly

    Humans use electronic devices for their own sake, and our interactions with them are often not gentle. We tend to drop them, turn them on and off frequently, and treat them roughly, Which easily damages them. Through hole can solve this problem.

    So we need to find a type of PCB which can Withstand this rough usage. And we find out the best way to make durable PCB boards is through hole technology assembly. Through-hole components with a long lead, then use them to assemble the PCB board. We need to insert their lead into the PCB hole.

    Using through-hole components, we can make out stronger bond PCB board than standard metal-based components because through-hole components are all with lead, which can be run through the hole of the PCB board, and then solder together. This structure makes the board and component joint more firm. It makes the PCB board work better under environmental stress. Some large, high-power and heavy components must be mounted on the PCB board with through-hole technology such as a transformer.

    Through-hole components are commonly used in various industries, such as aerospace, automotive, and military. They are ideal for rugged, durable components to work in harsh environmental conditions, such as collisions or extreme accelerations. Through-hole components can also be used for prototyping and testing.

    Application of Through Hole PCB Assembly

    Through-hole assembly is a more eco-friendly process that provides a stronger and more resilient connection between the components and the board. It eliminates the need for traditional soldering methods, which can lead to higher environmental stress. This process is ideal for aerospace and military industries due to its high-reliability requirements.

    Through holes can form a stronger bond by inserting the component leads into the PCB hole and soldering. So, it can make out the PCB applied under the environment with mechanical stress or high temperature. So through-hole technology is prevalent in manufacturing equipment used in military and aerospace industries.

    Through-hole components are commonly used in the production of PCBs, especially for testing and prototyping. In addition, they are easier to replace and reposition than standard components.

    Through-hole components are commonly used in various industrial equipment and machinery due to their high-stress tolerance and heat resistance. In addition, due to their bright and durable properties, through-hole LED lights can be found on giant billboards.

    Unfortunately, the through-hole assembly can be time-consuming and costly. This process involves drilling and holding the components using leads.

    Although through-hole assembly is commonly used in the production of PCBs, it is not ideal for multi-layer boards due to the need for holes through the board. Also, the total board size is larger than that of standard SMT PCBs, which restricts the applications of these boards.

    When Should You Consider using the Through Hole PCB Assembly?

    When we need PCB with a stronger bond, if a device is often turned on and off violently, we would need a more rugged and robust bond PCB, which would need through-hole technology to produce. Through-hole connections are solid. It is because they are mechanically stronger than surface-mounted connections.

    When we need a durable product for working in a stressful environment, its PCB board will meet the great challenge of mechanical stress if the devices need to work in a stressful environment. Their PCB board would need to be soldered firmly with its components. Compared to surface-mounted devices, through-hole leads are more eco-friendly and can endure environmental stress.

    The PCB board must be made with through-hole technology when it needs to work in a harsh environment, such as high temperature. For example, military, automobile, and aerospace equipment usually function in an extreme outdoor environment, so their PCB must be made with through-hole technology. Likewise, if you make a PCB prototype for testing, you’d better use a through-hole assembly of the PCB board.

    When you make the product used in the high-power circuit, specific surface-mounted devices (SMDs) are unsuitable for certain parts, such as those in power circuitry. Due to their properties, thermal cycling can damage these types of devices. However, using through-hole mounting technology, you can repair the damaged board by replacing the damaged component.

    When you make the product used under mechanical stress, through-hole mounting is a process that provides solid mechanical bonds, which is typically not available with surface-mount techniques. So through hole technology can be used to mount components that will likely experience mechanical stress due to the presence of this mechanical bond. Transformers are usually large, heavy components. They need to be mounted on a PCB board with through-hole technology.

    Through-hole capacitors can be assembled without a printed circuit board to save space. For instance, they can be over-moulded with plastic instead of metal. This process could create sensors for various applications, such as automobiles and cable harnesses.

    What Are the Types of Through Hole PCB Components?

    There are two types of through-hole PCB components on the market. One is a passive through-hole component, and the other is an active one. The PCB board layout design must be with a hole, and the hole needs to surround it with a soldering pad. These two types of components would be mounted the same way on the PCB board.

    The through-hole PCB components usually are the large size of components. They are with lead which would be manually inserted into the hole of the PCB and solder on the PCB board. That can make its bond more robust and more durable. The soldering method can be manual or wave soldering. Passive components’ lead is usually too long to use directly, so that those long leads would be cut short before use. After their lead is cut short, they can be mounted onto the PCB board.

    Axial and radial are two common types of passive through-hole components. An axial component has its electrical leads along its axis of symmetry, while a radial component has its leads along its axis of symmetry. An example of a typical through-hole component is a standard resistor with electrical leads along its cylindrical axis.

    Some components, such as high-power resistors, come in through-hole packages that are rectangular in shape. These components, often used in electrical equipment, have a lead wire running through the package’s length.

    Radical components have a feature that they have two leads out from one end of the component. That makes it occupy a narrow space. Many through-hole components are this radical type, such as switches, small relays, led, large capacitors etc.

    If you were in electronics classes in the 1980s, you probably remember using integrated circuits that were either plastic or dual-inline package (DIP).

    An op-amp package is the most common type of integrated circuit commonly used in a dual-inline package. Other standard components widely used in this package include high-power LED lights and quartz resonators.

    During the 1980s, designers focused more on making electronic systems more stable and less concerned with signal integrity and aesthetics. Through-hole components were also less likely to take up space.

    More and more products pursue low power consumption, stable signal, and small size. Through-hole technology can no longer meet this demand. Therefore, a new technology that is surface mount technology (SMT), has been developed to solve this problem.

    Information Related to Through-Hole Technology (THT)


    Through-hole PCB assembly technology is the best option when the PCB board is used under mechanical stress or a high-temperature environment. This is because it can make out a stronger bond of the PCB board. Besides, those through-hole components are easily replaced when these PCB boards are damaged.


    Weakness of the through-hole PCB assembly is costly, and assembly speed is slow because it needs to drill holes in the PCB and insert the component into the PCB board holes. In addition, the through-hole mounting needs drilling holes throughout the PCB layer, so some particular PCBs can't use through-hole assembly technology. For example, multilayers PCB can't use the through-hole mounting to assemble.


    Because no matter whether SMT assembly or through-hole PCB assembly, they both have their limit, so in Viasion, we can mix these two technologies to assemble PCB for customers and make out better solutions to meet customer requests. It means when we assemble a PCB, we use through-hole mounting in some steps, and in others, we use SMT technology.

    Why Is THT Still Popular?

    The assembling speed of surface mount technology is faster, and the price is lower than the through-hole technology. Therefore, it seems the surface mount technology is the clear winner compared to the through-hole technology. It is a superior technology for various applications of PCB manufacturing, such as those that are heavily involved in the design of mixed-signal and analogue devices, such as wearable electronics and Internet of Things (IoT) devices. As network speeds increase, surface mount components will likely remain increasing in demand due to more and more wearable and IoT devices being used.

    The increasing number of technology companies and the need for a connected society drive the demand for smaller, more compact PCBs. That is why the need for smaller and more cost-effective components is becoming more prevalent. With the ability to make PCBs in almost any form factor, we can now design them for various applications. The lower cost of production and the availability of less expensive components are some of the reasons why the end customer can expect to see more cost savings.
    Though through-hole technology can’t achieve the above request, in some conditions, through-hole technology performance is even better than SMT technology and irreplaceable.
    You must be careful when you design and assemble the PCB board for automobiles, aerospace, and the military. A minor error may lead to the breakdown of the product, which may cause serious accidents and irreparable losses in use. For instance, a component inserted into an interconnect using a through-hole can cause significant insertion loss.
    Through-hole components are commonly used in various applications which need very robust connections, such as industrial equipment, medical devices, automotive, aerospace, and military devices. As a result, they are less prone to failure when compared to traditional methods.

    When you make a printed circuit board prototype or test PCB, you’d better use through-hole PCB assembly technology because it can replace the defective components easily, which are already mounted on your board. In addition, some PCB boards need to be used in harsh environments. Therefore, they need to have a strong bond, such as those boards used in aerospace and military, which must be assembled using through-hole technology. This type of mounting technology makes the PCB board very durable, which is why it is commonly used in these industries.

    Through-hole technology is commonly used in various applications, such as LED lights. Comparing LEDs with SMT assembly, LEDs with through-hole PCB asembly are incredibly durable. LEDs with PTH assembly are widely used, such as traffic lights, outdoor displays, big screens in stadiums and billboards.

    Generally speaking, through-hole PCB assemblies are used in products which need to be extremely robust and durable. PTH assembly is often used in harsh environmental conditions, such as prolonged exposure to temperature, humidity or vibration extremes. For example, industrial equipment and machines, and aerospace or military equipment are built almost exclusively with through-hole components. So, despite the through-hole mounting technology is outdated and also has lots of disadvantages, it can still be used widely in today’s electronic devices.

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    Frequently Asked Questions

    Through-hole PCB assembly is the process of soldering through-hole components to a bare circuit board by wave soldering or manual soldering. In this process, the leads of the components need to pass through the drilled holes in the circuit board.

    Components on through-hole assembly are called through-hole components. Its abbreviation is THC. These components always have long pins to plug into plated through holes.

    Through-hole PCB assemblies are used in electronic products, mainly for all kinds of connectors. 

    The full form of THT PCBA is through hole technology printed circuit board assembly.

    Choosing through-hole PCB assembly or SMT PCB assembly depends on many factors.
    1) Surface mount technology allows for a higher level of automation, which means that circuit boards can be assembled at a faster rate. This allows you to handle PCBs in high volume and is more cost-effective than through-hole technology.
    2) If you have unique requirements, surface mount technology may be highly customizable and therefore the right choice. If you need a custom-designed PCBA, then the process of SMT assembly has the flexibility and power to deliver the desired results.
    3)With surface mount technology, components can be mounted to both sides of the circuit board. This double-sided PCB assembly means you can apply more complex circuits without having to expand the application.
    4)If your application must be subjected to high-stress levels (either mechanical or environmental) during operation, then the best choice for PCB assembly is through-hole.
    5)If your application must operate at high speeds and the highest levels under these conditions, then through-hole PCB assembly may be the right choice for you.
    6) If your application must operate at high and low temperatures, the through-hole PCB assembly with higher strength, durability, and reliability may be your best choice.
    7) If your application must operate and maintain its performance under high-pressure conditions, through-hole PCB assembly should be chosen.

    Of course, conformal coating is included in Viasion’s through-hole PCB assembly services.

    Yes, we offer X-ray testing for all products, and PCB with through-hole PCB assembly is no exception.

    Yes, Viasion will carry out a series of testing and inspection for all the products. The following states the main ways of testing and inspection in Viasion.
    1) Electrical Test (E-test)
    2) AOI (Automated Optical Inspection)
    3) ICT (In-circuit Test)
    4) FCT (Functional Test)
    5) X-ray inspection
    6) Visual inspection

    Yes, we will carry out quality inspections for through-hole PCB assembly according to IPC 610 and J-STD standards.

    Yes, Viasion will offer the first article inspection for any through-hole PCB assembly.

    1) 1 week for only PCB assembly
    2) 2-4 weeks for turnkey PCB assembly
    3) 4-10 weeks for Turnkey box build assembly

    Concerning the cost of the through-hole PCB assembly, the following factors should be taken into account.
    1) The cost of PCB
    2) The processing cost of THT assembly
    3) The purchase cost of components
    4) The cost of PCBA testing
    5) Turnaround time
    6) Quantity
    7) Packaging

    1) Through-hole PCB assembly provides a higher level of durability and reliability.
    2) For many years, through-hole technology has been considered the most reliable mounting process because it provides a strong mechanical bond between the circuit board and the components. The technology is also used for mounting larger components that are designed to withstand higher mechanical stresses.

    1. The efficiency of PTH assembly is much lower then that of SMT assembly;
    2. Since the components have leads, it is impossible to solve the problem of reducing the size after the circuit is dense to a certain extent;
    3. faults caused by the proximity of the leads to each other and interference caused by the length of the leads are difficult to eliminate.

    1) Layout
    1.1) For devices with a high pin count such as terminal blocks or flat cables, oval pads should be used instead of round pads to prevent tin bridges in the step of wave soldering.
    1.2) Make the spacing between positioning holes and the distance between the positioning holes and components as large as possible, and standardize and optimize the size according to the insertion equipment; Do not electroplate the positioning hole, because the diameter of the plating hole is difficult to control.
    2)Positioning and placement of components
    2.1) Double inline package devices, connectors, and other high pin count components will be arranged in the direction of the wave soldering over straight, which can reduce the tin bridge between the component pins.
    2.2) Make full use of silkscreen to mark on the surface of the board, such as drawing a box for a barcode, printing an arrow to indicate the direction of the board over the wave soldering, tracing the bottom component outline with a dotted line, etc.
    2.3) Drawing component reference marks as well as polarity indications and ensuring that these reference marks and indications remain visible after the components are inserted, which is helpful during inspection and troubleshooting and is also a good maintenance exercise.
    2.4) Components from the edge of the board should be at least 1.5 mm (preferably 3 mm), which will make the circuit board easier to transfer and will be helpful for wave soldering. The damage to peripheral components becomes smaller.
    2.5)Make the components evenly distributed on the PCB to reduce warpage and help dissipate heat evenly in the wave soldering step.

    The simplified process flow of through-hole PCB assembly: Plug-in → pre-application of flux → wave soldering → pin cutting → testing