—、 Overlapping pads
1. The overlapping of pads (except surface mount pads) means the overlapping of holes. During the drilling process of the circuit board, the drill bit will be broken due to multiple drilling in one place, resulting in damage to the hole.
2. Two holes in the PCB multilayer board overlap, for example, one hole is an isolation plate, and the other hole is a connection plate (flower pad), so that after drawing the negative, it will appear as an isolation plate, resulting in scrap.
二、 the abuse of graphics layer
1. Some useless connections were made on the graphics layer of some circuit boards. It was originally a four-layer circuit board but more than five layers of circuits were designed, which caused misunderstanding.
2. To save trouble when designing the diagram, take Protel software as an example to draw the lines on each layer with the Board layer, and use the Board layer to mark the lines. In this way, when performing light drawing data, because the Board layer is not select, missing If the connection is broken, or it will be short-circuited due to the selection of the label line of the Board layer, so the design layer should be kept complete and clear.
3. Violation of the conventional design, such as the design of the component surface on the Bottom layer and the design of the soldering surface on the Top layer, causing inconvenience.
三.、Misplacement of characters
1. The SMD pad of the character cover pad brings inconvenience to the on-off test of the printed board and the welding of components.
2. If the character design is too small, it will cause difficulty in screen printing. If it is too large, the characters will overlap and it is difficult to distinguish.
四、the setting of the aperture of the pad on one side of the circuit board
1. The pads on one side of the circuit board 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 coordinates of the hole appear at this position, and problems arise.
2. Single-side pads such as drilling holes should be specially marked.
五、 Draw pads with filler blocks
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, resulting in Device soldering is difficult.
六、 the electrical ground is a flower pad and a connection
Because the power supply is designed as a flower pad, the ground layer is opposite to the image on the actual printed board, and the designer should be very clear that all the connections are isolated lines. Here, by the way, care should be taken when drawing several groups of power supplies or isolation lines of several grounds, so that no gaps can be left to short-circuit the two groups of power supplies, and the area of the connection cannot be blocked (so that one group of power supplies is separated).
七、The definition of processing level is not clear
1. 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 device on the manufactured board.
2. For example, a four-layer circuit board is designed with TOP mid1, mid2 bottom four layers; but it is not placed in this order during processing, which requires an explanation.
八、There are too many filling blocks in the design or the filling blocks are filled with extremely thin lines
1. The photoplotting data may be lost, and the photoplotting data is incomplete.
2. Since the filling block is drawn one by one in the process of light drawing data, the amount of light drawing data generated is quite large, which increases the difficulty of data processing.
九、 Uneven circuit board graphic design
In the process of graphic electroplating, the plating layer is uneven, which affects the quality.
十、 The spacing of large-area grids is too small
The edge between the lines forming the large-area grid line is too small (less than 0.3mm). During the manufacturing process of the printed board, many broken films are likely to be attached to the board after the image transfer process is completed, resulting in broken lines.
十一、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 it is easy to cause the copper foil to warp and cause the solder resist to fall off if it is milled on the copper foil when milling the shape.
十二、The outline frame design is not clear
Some customers have designed outline lines on Keeplayer, Board layer, Top over layer, etc. and these outline lines do not overlap, making it difficult for PCB manufacturers to judge which outline line to use.
十三、 the surface mount device pad is too short
This is for on-off testing, for surface mount devices that are too dense; the distance between the two pins is quite small and the pads are also very thin, and the installation test pins must be staggered up and down (left and right), such as the pad design If it is too short, although it will not affect the installation of the device, it will make the test pins not staggered.
十四、The special-shaped hole is too short
The length/width of the special-shaped hole should be ≥2:1, and the width should be >1.0mm, otherwise, the drilling machine will easily break the drill when processing the special-shaped hole, which will cause processing difficulties and increase costs.
