PCB Technical - PCBA inspection control through-hole component insertion

After the surface mount component is soldered in place after the reflow soldering process, the PCBA cannot be completed, and the assembled circuit board needs to be tested for function. Generally, movement during the reflow process will result in poor connection quality or no connection at all. Shorts are also a common side effect of this exercise, because misplaced components sometimes connect parts of the circuit that shouldn't be connected.

Checking for these errors and misalignments may involve one of several different checking methods. The most common inspection methods include:

Manual inspection: Although automation and intelligent manufacturing are about to develop, manual inspection is still required during the PCB assembly process. For smaller batches, on-site visual inspection by the designer is an effective way to ensure the quality of the PCB after the reflow soldering process. However, as the number of inspection boards increases, this method becomes increasingly impractical and inaccurate. Observing these small components for more than an hour can cause optical fatigue, which can lead to inaccurate inspections.

Automatic optical inspection: Automatic optical inspection is more suitable for large-scale inspection method PCBA. Automatic optical inspection machines, also known as AOI machines, use a series of high-power cameras to "see" the PCB. These cameras are arranged at different angles to view the welded connection. Different quality solder connections reflect light in different ways, allowing AOI to recognize lower quality solder. AOI completes this work at a very high speed, enabling it to process a large number of PCBs in a relatively short time.

X-ray inspection: Another inspection method involves X-rays. This is a less common inspection method-it is most commonly used for more complex or layered PCBs. X-rays allow the observer to see through the layers and visualize the lower layers to identify any potential hidden problems.

The fate of defective boards depends on PCBA's standards, and they will be sent back to be cleaned, reprocessed or scrapped.

Check if one of the errors is found. The next step in the process is to test the part to make sure it does what it is supposed to do. This involves testing the quality of the PCB connection. Boards that need to be programmed or calibrated require more steps to test the correct function.

This type of inspection can be carried out regularly after the reflow process to identify any potential problems. These regular inspections can ensure that errors are found and fixed as quickly as possible, which helps manufacturers and designers save time, manpower and materials.

Through hole component insertion

According to the type of circuit board under PCBA, the circuit board may contain various components besides conventional SMD. These include plated through-hole components or PTH components.

Plated through hole is a hole on the PCB, which is always plated on the circuit board. PCB components use these holes to pass signals from one side of the circuit board to the other. In this case, the solder paste will not be of any benefit, because the solder paste will pass directly through the hole without a chance of sticking.

PTH components require more professional soldering instead of solder paste soldering methods in the subsequent PCB assembly process:

Manual soldering: Manual through-hole insertion is a simple process. Usually, the task of one person at a single site is to insert a component into a specified PTH. When finished, the circuit board will be transferred to the next workstation, and someone else is inserting another component. Each PTH that needs to be equipped will continue to circulate. This can be a long process, depending on how many PTH components need to be inserted during one cycle of the PCBA. For this purpose, most companies specifically try to avoid using PTH components for design, but PTH components are still very common in PCB design.

Wave soldering: Wave soldering is an automated version of manual soldering, but involves a very different process. After placing the PTH assembly in place, place the board on another conveyor belt. This time, the conveyor belt passes through a special oven, where a stream of molten solder washes on the bottom of the circuit board. This will immediately solder all the pins on the bottom of the board. This kind of soldering is almost impossible to use for double-sided PCBs, because soldering the entire PCB surface makes any sophisticated electronic components unusable.

After the soldering process is completed, the PCB can continue to undergo the final inspection, or if the PCB needs to add additional parts or assembly on the other side, it can complete the front