PCB Technical - Common problems made by circuit board design engineers

1. The level definition is not clear, especially the single-panel design is in the TOP layer. If you do not specify the pros and cons, the board may be reversed.

2. Draw pads with filling blocks

Drawing pads with filler blocks can pass the DRC inspection when designing the circuit, but it is not good for processing. Therefore, similar pads cannot directly generate solder mask data. When solder resist is applied, the filler block area will be covered by the solder resist, resulting in the device Difficulty in welding.

3. The large area of copper foil is too close to the outer frame

The distance between the large area copper foil and the outer frame should be at least 0.2mm or more. If V groove is required, it should be as much as 0.4mm or more. Otherwise, when milling the shape of the copper foil, it will easily cause the copper foil to warp and cause solder resist shedding problem.

4. The electrical ground layer is also a flower pad and a connection

Because it is designed as a flower pad power supply, the ground layer is opposite to the actual printed board image. All connections are isolated lines. When drawing several sets of power or ground isolation lines, you should be careful not to leave gaps and make two sets A short circuit of the power supply cannot cause the connection area to be blocked.

5. There are too many filling blocks in the design or the filling blocks are filled with very thin lines

The light drawing data is lost and the light drawing data is incomplete. Because the filling blocks are drawn with lines one by one during the light drawing data processing, the amount of light drawing data generated is quite large, which increases the difficulty of data processing.

6. The surface mount device pad is too short

This is for the continuity test. For too dense surface mount devices, the distance between the two pins is quite small, and the pads are also quite thin. The test pins must be installed in a staggered position. For example, the pad design is too short, although not Affect the device installation, but will make the test pin staggered.

7. Random characters

Character cover pad SMD soldering piece, which brings inconvenience to the continuity test of the printed board and component soldering. The character design is too small, which makes screen printing difficult, and too large will make the characters overlap and make it difficult to distinguish.

8. Single-sided pad aperture setting

Single-sided pads are generally not drilled. If the drilled holes need to be marked, the hole diameter should be designed to be zero. If the value is designed, then when the drilling data is generated, the hole coordinates will appear at this position, and there will be a problem. Single-sided pads such as drilling should be specially marked.

9. 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 overlapped, and the negative film appeared as an isolation disk after drawing, resulting in scrap.

10. Graphic layer abuse

Some useless connections were made on some graphics layers, but it was originally a four-layer board but designed with more than five layers, which caused misunderstanding. Violation of conventional design. The graphic layer should be kept intact and clear when designing.