Ten defects of PCB circuit board design process
PCB circuit boards are widely used in various electronic products in today’s industrially developed world. According to different industries, the color, shape, size, layer, and material of PCB circuit boards are different. Therefore, clear information is required in the design of PCB circuit boards, otherwise misunderstandings are prone to occur. This article summarizes the top ten defects based on the problems in the design process of PCB circuit boards.
1. The definition of processing level is not clear
The single-sided board is designed on the TOP layer. If there is no instruction to do it front and back, it may be difficult to solder the board with devices on it.
2. The distance between the large area copper foil and the outer frame is too close
The distance between the large-area copper foil and the outer frame should be at least 0.2mm, because when milling the shape, if it is milled on the copper foil, it is easy to cause the copper foil to warp and cause the solder resist to fall off.
3. Use filler blocks to draw pads
Drawing pads with filler blocks can pass the DRC inspection when designing circuits, but not for processing. Therefore, such pads cannot directly generate solder mask data. When solder resist is applied, the area of the filler block will be covered by solder resist, causing the device Welding is difficult.
4. The electric ground layer is a flower pad and a connection
Because it is designed as a power supply in the form of pads, the ground layer is opposite to the image on the actual printed board, and all connections are isolated lines. Be careful when drawing several sets of power supply or several ground isolation lines, and do not leave gaps to make the two groups A short circuit of the power supply cannot cause the connection area to be blocked.
5. Misplaced characters
The SMD pads of the character cover pads bring inconvenience to the on-off test of the printed board and component welding. If the character design is too small, it will make screen printing difficult, and if it is too large, the characters will overlap each other, making it difficult to distinguish.
6.surface mount device pads are too short
This is for on-off testing. For too dense surface mount devices, the distance between the two pins is quite small, and the pads are also very thin. When installing the test pins, they must be staggered up and down. If the pad design is too short, although it is not It will affect the installation of the device, but it will make the test pins inseparable.
7. Single-side pad aperture setting
Single-sided pads are generally not drilled. If the drilled holes need to be marked, the aperture should be designed as zero. If the value is designed, then when the drilling data is generated, the hole coordinates will appear at this position, and problems will arise. Single-sided pads such as drilled holes should be specially marked.
8. Pad overlap
During the drilling process, the drill bit will be broken due to multiple drilling in one place, resulting in hole damage. The two holes in the multi-layer board overlap, and after the negative is drawn, it will appear as an isolation plate, resulting in scrap.
9. There are too many filling blocks in the design or the filling blocks are filled with very thin lines
The photoplotting data is lost, and the photoplotting data is incomplete. Because the filling block is drawn one by one in the light drawing data processing, so the amount of light drawing data generated is quite large, which increases the difficulty of data processing.
10. Graphic layer abuse
Some useless connections have been made on some graphics layers. It was originally a four-layer board but more than five layers of circuits were designed, which caused misunderstandings. Violation of conventional design. The graphics layer should be kept intact and clear when designing.