PCB Defects Summarized By Manufacturers With 10 Years of Experience

Ensuring the quality of the PCB is the basic requirement of the PCB manufacturer, but various problems will be encountered during the production process that lead to defects in the PCB. How to avoid the problem is the key that should be considered in PCB manufacturing. The following are the common causes and measures of PCB defects summarized by PCB  manufacturing engineers with decades of experience

Causes and measures of common PCB  defects in processing:

Pad overlap: When drilling, heavy holes or broken drills are caused by multiple drilling in one place, or the hole diameter becomes larger or offset. If it is a multi-layer board, when there is both a connecting disk and an isolation disk at the same position, the PCB board is displayed as isolated and the connection is wrong.

Non-standard graphics layer: unreasonable graphic layer design, or there is much design garbage on each layer, such as useless borders, broken lines, labeling, etc., which are easy to causes misunderstanding and lead to unnecessary scrapping.

The characters are unreasonable: the characters are too small, the difficulty of screen printing increases, the characters are too large, and the characters are easy to overlap and overlap when printing, which is difficult to distinguish, or the characters cover the SMD solder sheet, which brings inconvenience to the PCB on-off detection and component welding, and the character size is generally > under normal circumstances40mil。

Pad setting hole diameter: For some single-sided soldering PCB boards, the pad is generally not drilled, and the hole diameter should be designed to be zero, otherwise drilling data will be generated in the manufacturing process.

The moment between the grid lines is too small: when the moment between the grid lines < 0.3mm, the film will be broken after the development of the graphic transfer process during production, which will improve the difficulty of PCB manufacturing.

The shape of the frame is not clear: the multi-layer PCB board edge is designed with a frame, but it does not coincide, the circuit board manufacturer in the manufacturing process, it is difficult to judge which line is formed, the standard frame should be designed in the mechanical layer or BOARD layer, the internal hollowing out part should be clear, when the graphic design is uneven, in the process of constitutional electroplating, the uniform coating is affected, resulting in board warping.

The special-shaped aperture should be set to 2:1/1.0mm, and there are at least 2 or more positioning holes with a diameter of >1.5mm on the PCB.

The inner layer of the PCB multi-layer board is unreasonable, when the heat dissipation pad is placed on the isolation belt, it is easy to be unable to connect after drilling, and the isolation belt is too narrow to accurately judge the grid, for the buried blind hole circuit board, the density of the multi-layer board should be increased by more than 30%, the number of layers of the multi-layer board should be appropriately reduced and the size of the multi-layer board should be reduced, and the performance of the circuit board should be improved, which is controlled by the characteristic impedance.

The above is just a part of the PCB defects, and new discoveries will continue to be shared in the future. If you have a better way, I look forward to your message.The PCB manufacturing process is very complex, especially HDI, multi-layer rigid and flexible PCB, which require high-tech PCBs.

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