Top ten difficulties in design of pcb board prototype manufacturing

2019-11-12 22:22:39 Juding Circuit Technology

First, the PCB prototype processing level definition is not clear

The single-panel design is in the TOP layer. If you do not explain the positive and negative, you may make the board and install the device without soldering.

Second, the PCB prototype large area copper foil is too close to the outer frame

Large-area copper foil should be at least 0.2mm or more from the outer frame, because it is easy to cause the copper foil to rise and cause the solder resist to fall off when milling to the copper foil.

Third, the PCB prototype fills the pad with a pad

Draw a pad with a pad to pass the DRC check when designing the line, but it is not suitable for processing. Therefore, the pad cannot directly generate solder resist data. When the solder resist is applied, the pad area will be covered by the solder resist, resulting in the device. Welding is difficult.

Fourth, the PCB prototype electric ground layer is a flower pad and a connection

Because the design is a flower pad mode power supply, the ground layer is opposite to the actual printed board image. All connections are isolated lines. Care should be taken when drawing several sets of power supplies or several ground isolation lines. The power supply is short-circuited and cannot cause the connection area to be blocked.

Five, PCB prototype characters messed up

The character cover pad SMD soldering piece brings inconvenience to the printed board on-off test and component soldering. Character design is too small, making screen printing difficult, too large will make characters overlap each other, difficult to distinguish.

Sixth, PCB prototype surface mount device pads are too short

For the continuity test, for a too dense surface mount device, the spacing between the two legs is quite small, and the pads are also relatively thin. The test pins must be placed up and down, such as the pad design is too short, although not Affects device mounting, but causes the test pin to be misplaced.

Seven, single-sided pad aperture setting

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

Eight, PCB prototype pad overlap

In the PCB prototype manufacturing drilling process, the drill bit is broken due to multiple drilling in one place, resulting in hole damage. The two holes in the multi-layer board overlap, and the negative film is formed as a spacer disk, which causes scrapping.

Nine, the PCB prototype design has too many filling blocks or the filling block is filled with very thin lines

There is a loss of the generated light data, and the light data is not complete. Because the filling block is drawn by lines one by one during the processing of the light drawing data, the amount of light drawing data is quite large, which increases the difficulty of data processing.

Ten, graphics layer abuse

Some useless connections were made on some graphics layers. The original four-layer board was designed with more than five layers, which caused misunderstanding. Violation of routine design. The graphics layer should be kept complete and clear during design.

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