Common errors during PCB manufacturing

(1) Pad overlap:

a. Resulting in heavy holes, broken holes damage to the holes due to multiple drilling in one place during drilling.

b. In a multilayer board, there are both a connection disk an isolation disk at the same location. The board behaves as? Isolation connection error.

(2) The graphics layer is standardized:

a. It violates the conventional design. For example, the component surface is designed in the Bottom layer the solder surface is designed in the TOP layer, which is misleading.

b. There are a lot of design garbage on each layer, such as broken lines, useless borders, labels, etc.

(3) Unreasonable characters:

a. The characters cover the SMD pads, which brings inconvenience to the PCB continuity detection component welding.

b. Characters are too small, making screen printing difficult. Too large will make the characters overlap each other it is difficult to distinguish. The font is generally> 40mil.

(4) Single-sided pad setting aperture:

a.Single-sided pads are generally drilled, the hole diameter should be designed to zero, otherwise the coordinates of the hole appear at this position when drilling data is generated. If drilling is to be done, special instructions should be given.

b. If single-sided pads need to be drilled, but no aperture is designed, the software will treat the pads as SMT pads when outputting electrical ground data, the inner layer will lose the isolation disk.

(5) Use pads to draw pads: Although they can pass the DRC inspection, they cannot directly generate solder mask data during processing, the pads cannot be soldered with solder mask.

(6) The electrical ground is designed with both a heat sink a signal line. The positive negative images are designed together an error occurs.

(7) Large-area grid spacing is too small: the grid line spacing is less than 0.3mm. During the PCB manufacturing process, the graphic transfer process generates broken films after development causes disconnection. This increases processing difficulty.

(8) The graphic is too close to the outer frame: at least a distance of 0.2mm (0.35mm more at the V-cut) should be ensured, otherwise the copper foil will be warped the solder resist will fall off during the shape processing. The appearance quality (including multiple layers) The inner copper layer of the board).

(9) The shape of the frame is clear: Many layers have designed frames they do overlap, which makes it difficult for PCB manufacturers to determine which line to form. The standard frame should be designed on the mechanical layer the BOARD layer, the internal hollowed-out part must be clear.

(10) Graphic design unevenness: When the graphic plating is performed, the current distribution is uneven, which affects the coating uniformity even causes warpage.

(11) Special-shaped hole is short: the length / width of the special-shaped hole should be> 2: 1 the width> 1.0mm, otherwise the CNC drilling machine cannot process.

(12) Milling shape positioning holes are designed: If possible, design at least two positioning holes with a diameter of> 1.5mm in the PCB board.

(13) Unclear aperture marking:

a. Aperture marking should be marked in metric as much as possible, in 0.05 increments.

b. Combine as many pores as possible into one reservoir area.

c. Whether the tolerances of metallized holes special holes (such as crimp holes) are clearly marked.

(14) Unreasonable wiring inside the multilayer board:

a. The heat dissipation pad is placed on the isolation tape, it is easy to fail to connect after drilling.

b. The gap is designed with gaps, which is easy to misunderstand.

c. The design of the isolation belt is too narrow to accurately judge the network

(15) Design issues for buried blind plate

Significance of designing buried blind plate:

a. Increase the density of the multilayer board by more than 30%, reduce the number of layers reduce the size of the multilayer board

b. Improve PCB performance, especially control of characteristic impedance (shortened lead, reduced aperture)

c. Increase PCB design freedom

d. Reduce raw materials costs, which is good for environmental protection.

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