Printed circuit board assembly visual inspection

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During the processing of pcb boards, inspection is required, and visual inspection is a more important one. Many defects or quality defects on the PCB board can be identified through visual inspection, so that effective measures can be taken to improve and continuously improve product quality. When performing visual inspections, some simple optical instruments are sometimes used. For those PCB board manufacturers with imperfect production equipment and testing equipment, visual inspection is essential to improve product quality.

In PCB board processing, visual inspection is mainly used in solder paste printing, component placement and welding completion. The contents include: PCB board manual inspection, glue point visual inspection, solder joint visual inspection and surface quality visual inspection, etc.

1.Solder paste printing

First check whether the parameters of the solder paste printing machine are set correctly; whether the height of the solder paste is consistent or in a "trapezoidal" shape, the edges of the solder paste cannot be rounded or collapsed into a pile, but some are allowed to pull up a small amount due to the detachment of the steel plate the peaked shape caused by the solder paste. If the solder paste is unevenly distributed, it is necessary to check the solder paste on the scraper, whether there is insufficient or not distribution, and check the printed steel plate and other parameters. Finally, check under the microscope whether the solder paste is bright after printing.

2. Component placement

Before the first PCB with good solder paste starts to insert components, visually check whether the material rack is placed properly, whether the components to be used meet the production requirements, and whether the reclaiming position of the equipment is accurate. After the first PCB is completed, check each component carefully to see if they are properly placed and lightly pressed in the center of the solder paste. If the solder paste pressed against the component is slightly depend the microscope, it means that the component is placed correctly. Also visually inspect all components on the BOM list to see if they are consistent with the components on the PCB, more importantly, visually inspect those components that are sensitive to positive and negative electrodes, such as diodes, tantalum electrolytic capacitors, and ICs etc, to see if they are placed in correct orientation.

In order to ensure that Printed Circuit Boards (PCBs) are functioning as intended, manufacturers need to confirm that all components are assembled correctly. This is achieved through a variety of techniques, ranging from simple manual inspections to automated tests that utilize advanced PCB inspection equipment.

Manual visual inspections are a good starting point, and for simpler units, they may be sufficient. At Electronic Manufacturing Services Group, we perform a manual visual inspection under magnification of every board we produce to ensure that we meet all customer expectations. We also offer other inspection services that require the use of advanced equipment. This equipment can speed up the inspection process and may be necessary for more complex board types, such as multi-layer boards and those with a high number of components.