Through-hole or THT technology involves drilling holes in a PCB, and then electronic components should be soldered into these holes to connect to the tracks on the PCB. This is an older technology than surface mount. Despite being an older technology, through-hole PCB assembly has advantages. Through-hole mounting strengthens the bond between the board and its components, resulting in more robust, shock and vibration resistant devices.

　　 Why use Through-Hole PCBA Technology:

　　PCB design has evolved from single-sided boards to double-sided boards and finally to multilayer boards. Through-hole assembly is very difficult to meet the demands of contemporary electronics. In today's PCB production, SMT technology has almost completely replaced through-hole manufacturing. However, through-hole assembly is still required in some applications, such as electrolytic capacitors, connectors, and large transformers.

　　PCB DIP connectors have better mechanical strength than most SMD connectors. In contrast, the bonding strength of PCB surface mount components does not exceed the bonding strength of the surface of the multilayer PCB board. The process of through-hole PCBA technology fixes components suitable for high-reliability equipment that requires strong connections between different conductive layers in the PCBA. Surface mount devices (SMDs) are simply soldered to the surface of the board via SMT assembly technology, while through-hole fixed DIP components have leads that pass through the entire board, enabling the component to withstand greater environmental stress. If too much solder is used, it may bridge to other connections and cause a short circuit. If too little solder is used, the joint may not be strong enough. Cold solder joints may break, while overheating the connection may damage the component or the board.

　　Therefore, through-hole PCBA assembly technology is commonly used in military, automotive, and aerospace products that experience high acceleration, collisions, or temperatures. Through-hole assembly technology is also suitable for test and prototyping applications where manual adjustment and replacement of equipment is required.

　 　THT Technology Characteristics

　　When using through-hole assembly, the PCB and PCB components are first prepared. Holes are then drilled in the board, sized to precisely fit the component leads. After inserting the leads into the holes, they are soldered to the board, securing them in place and creating a strong, lasting connection. This is a significant characteristic of through-hole assembly, making it so reliable and allowing it to continue serving numerous industries.

　　Through-hole technology allows for multiple components to be mounted on the PCBA, with engineers using two types of components throughout the process. Some examples include:

　　 Axial Lead Components

　　Axial lead components are significantly characterized by their symmetrical shape. These DIP PCB components are typically cylindrical with one or more leads extending from each end. With each lead end passing through a hole, axial components sit lower on the board and may occupy a larger or smaller area depending on lead placement. These components may include resistors, inductors, and capacitors.

　　 Radial Lead Components

　　Radial lead components are typically cylindrical or rectangular box-shaped, encompassing various capacitors, resistors, and inductors. The fundamental difference between these components and axial lead components is that the leads of the former emerge from one side rather than both ends. Connecting these components to the PCB board occupies significantly less space than using axial leads, but also offers less placement freedom.

　　 Advantages of Through-Hole Technology

　　Bond Strength

　　Through-hole assembly involves inserting the necessary components into the board and then connecting them with metallic solder, which strengthens the connection between the circuit and its components. Keeping all components of a circuit intact is crucial when using electrical equipment. Therefore, through-hole assembly is a better choice for high-risk electrical equipment compared to alternative methods such as surface mount soldering.

　　 Durability

　　The tighter the connection between circuit components, the stronger the durability, able to withstand harsher environments without significant wear or damage. If components suitable for aerospace industries or heavy machinery are needed, through-hole assembly technology is a good choice and has a longer lifespan than other technologies. In the long run, durable circuits will save on replacement costs.

　　 Reliability

　　Take the time to consider whether the PCBA will withstand the test each time it is used in a machine. Using through-hole PCBA assembly solutions eliminates this uncertainty due to the reliability of the drilling and soldering technology. Reliable products can alleviate your concerns and help you maintain a high level of operational efficiency, which is crucial in demanding or fast-paced environments.

　　 PCBA Through-Hole Soldering Machine

　　There are many through-hole soldering machines on the market today, all with different significant characteristics. Sometimes, these machines are also referred to as soldering robots. The primary use of these robots is to solder electronic through-hole components to PCBs. Most soldering machines follow these two principles:

　　Wave soldering: Wave soldering, as the name suggests, uses a liquid "wave" generated by motor movement to connect the PCB and parts. Tin has been melted into the liquid. This process is completed in a wave soldering machine.

　　Selective soldering: Selective soldering uses a solder fountain to solder specific through-hole DIP components on the PCB. A flux sprayer, preheater, and solder pot feeding the solder fountain are all part of the machine. The solder fountain or solder head moves from below to the soldering position.