What are the common problems in PCB proofing design? Do you know that?/You know what? Here’s a brief introduction from Shenzhen PCB proofing manufacturers!
1. Stacking of PCB proofing pads
1. The stacking of bonding pads (except external bonding pads) means the stacking of holes, which will break the drill bit and damage the holes due to repeated drilling in one place in the drilling process.
2. Two holes in the multilayer board are stacked, such as one hole position is a barrier disk and the other hole position is a connecting disk (flower pad). After the negative film is drawn like this, it is shown as a barrier disk, and the composition is invalid.
Second, the misuse of graphics layer
1. Some useless connections have been made on some graphic layers, but the lines with more than five layers have been planned, which constitutes a misunderstanding.
2. When planning, it saves effort. Taking Protel software as an example, all the lines in each layer are drawn with the Board layer and marked with the Board layer. In this way, when light drawing data is carried out, because the Board layer is not selected, the connection is missed and the circuit is broken, which may be short-circuited by selecting the marked line of the Board layer. Therefore, when planning, the graphics layer should be intact and clear.
3. Violation of conventional planning, for example, the component plane is planned at the Bottom layer and the welding plane is planned at the Top, which is inconvenient.
Third, the misplacing of characters
1. SMD welding of the character cover pad brings inconvenience to the on-off inspection of the printed circuit board and the welding of components.
2. The layout of characters is too small, which makes screen printing difficult. Too large will make characters stacked on top of each other, making it difficult to distinguish.
Four, PCB proofing single-sided pad aperture settings
1. Generally, single-sided pads are not drilled. If drilling holes need to be marked, their aperture should be planned to be zero. The numerical value is assumed, so that when drilling data occurs, this position presents the coordinates of the hole, and presents a problem.
2. Single-sided pads such as drilling holes shall be specially marked.
Fifth, draw the pad with the filler block.
Drawing pads with filler blocks can pass DRC inspection in line planning, but it is not necessary for processing, so similar pads can’t directly generate solder resist data. When solder resist is applied, the filler block area will be covered by solder resist, which makes it difficult to solder equipment.
Sixth, the electrical stratum is a flower pad and a connecting line.
Because of the power supply of the planned flower pad method, the formation is opposite to the image on the practical printed board, and all the connections are barrier lines, which should be very clear to the planner. Here, take the opportunity to say that you should be careful when drawing the barrier lines of several groups of power supplies or several fields. You should not leave gaps, which will short-circuit the two groups of power supplies, or close the connected area (separate one group of power supplies).
Seven, PCB proofing processing level boundary is not clear.
1. The single panel is planned on the TOP floor. If the front and back are not clarified, the manufactured board may be equipped with equipment and not welded well.
2. For example, when planning a four-layer board, four layers are selected, but they are not placed in this order during processing, which requires clarification.
Eight, there are too many filler blocks in the plan or filler blocks are filled with extremely thin lines.
1. The photo-drawing data is lost, and the photo-drawing data is incomplete.
2. Because the filling blocks are drawn line by line during the photo-drawing data processing, the amount of photo-drawing data generated is appropriately large, which increases the difficulty of data processing.
Nine, the surface mounting equipment pad is too short.
This is for on/off inspection. For too dense external mounting equipment, the interval between two feet is properly small, and the pads are also properly thin. It is necessary for the inspection pins of the equipment to be staggered up and down (left and right). For example, if the pad is planned too short, although it will not affect the equipment, it will make the inspection pins wrong.
Ten, the interval of large area grid is too small.
The edges between the same lines that make up the large-area grid lines are too small (less than 0.3mm). In the manufacturing process of printed boards, many broken films are attached to the boards briefly after the image is developed, resulting in broken lines.
XI. The interval between large-area copper foil and outer frame is too close.
The distance between the large-area copper foil and the outer frame should be at least 0.2mm, because when milling the shape, such as milling on the copper foil, the copper foil will become warped and the solder resist will drop.
XII. Unclear outline border planning
Some customers have planned outline lines while waiting, and these outline lines do not coincide, so it is difficult for PCB manufacturers to determine which outline line is the standard.
XIII. Uneven graphic planning
During pattern electroplating, the coating is uneven, which affects the quality.
XIV. The special 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 make the processing difficult and increase the cost.