PCB Technical - What are the common problems of PCB copy board?

What are the common problems of PCB copy board?

1. Unreasonable character placement

1. The SMD soldering pad of the character cover pad brings great inconvenience to the welding of PCB components and the on-off test of the circuit board.

2. The character design is too small, which makes the screen printing difficult, while too large will cause the characters to stack on top of each other and become difficult to distinguish.

Second, the PCB processing industry cannot clarify

1. The single-sided board is designed on the TOP layer. If you don't explain it, you can do it positively or negatively. The finished board is also lacking in good soldering when the components are installed.

2. For example, a four-layer board is designed with four layers of TOP mid1 and mid2 bottom, but the circuit board is not placed in such a sequence during processing, which requires clarification.

Three, draw pads with filling blocks

When designing the circuit, drawing pads with filler blocks can go through DRC introspection, but circuit board processing is not possible, because such pads cannot directly generate solder mask data. When solder resist is applied, the filler block area will be Solder resist masking makes it difficult to solder the device.

Fourth, the setting of the single-sided pad aperture

1. Ordinary single-sided pads do not need to be drilled. If they need to be drilled, they should be marked, and the hole diameter should be designed to be zero. If the value is designed, perhaps when drilling data occurs, this position will show the coordinates of the hole, and the problem will appear.

2. If a single-sided pad needs to be drilled, it should be marked out.

Five, the stacking of pads

1. The stacking of pads (except the surface mount pads) means the stacking of holes. During the drilling process, the drill bit will be broken due to repeated drilling in one place, causing damage to the hole.

2. In the multi-layer board, two holes are stacked. One hole should be the isolation disk and the other hole should be the connection disk. Otherwise, the film will appear as an isolation disk after drawing the film, which will be scrapped.

Sixth, the abuse of the graphics layer

1. Useless connections are made on some graphics layers, that is, four-layer boards are designed with more than five layers of circuits, which will cause misinterpretation.

2. Save trouble during design. Take the 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 the light drawing data is not selected, the Board layer is missing, If the connection is disconnected, it may be short-circuited due to the selection of the label line of the Board layer. Therefore, the design of the graphic layer should be intact and clear.

3. Violation of conventional design, such as the component surface is designed on the Bottom layer and the soldering surface is designed on the Top, causing unnecessary trouble.

Seven, the electrical ground layer is also a connection and a flower pad

Since the power supply is designed as a flower pad method, the ground layer is opposite to the image on the actual PCB board. All the connections are isolated lines. The designer should be very clear about this. When drawing several sets of power or ground isolation lines, pay attention to not leaving gaps, short-circuiting the two sets of power supplies, and blocking the area where the connection is formed.

8. There are too many filling blocks in the meter or the filling blocks are filled with very thin lines

1. The light-painting data is lost, and the light-painting data is incomplete.

2. The filling block is drawn with lines one by one during the processing of the light drawing data. Therefore, the amount of light drawing data generated is quite large, which increases the difficulty of data processing.

Nine, the spacing of the area grid is too small

The edges between the same lines that make up a large area of grid lines are too small (less than 0.3mm). In the circuit board manufacturing process, after the image transfer process is completed, a lot of broken films are easily attached to the board, forming a broken line.

Ten, do not understand the design of the frame

Some customers have designed contour lines for Keep layer, Board layer, Top over layer, etc. and these contour lines do not overlap, which makes it difficult for PCB manufacturers producing PCB copy boards to determine which contour line shall prevail.