Design a complete PCB circuit board , which requires many tedious and complicated processes. Generally , it mainly includes clarifying product requirements, hardware system design, device selection, PCB drawing, PCB production proofing, welding debugging and other steps.
Generally, designers have their own design quality checklists, some of which come from the company or department. The other part comes from the specifications of the design and the other part comes from the summary of our own experience. Special inspections include DRC inspection and DFM inspection of the design. These two parts focus on the PCB design output and back-end processing photolithography files.
For beginners designing PCB, they often encounter some common low-level problems due to lack of experience and imprecise design. A designed product cannot succeed in one go, it may take several revisions to succeed, and there may be omissions during the revision process. Some common problems ,for example : Broken line.
What is a broken line? As the name suggests, it is a line without a beginning or an end, or a line that is disconnected from the network .
The following will explain how Huaqiu DFM software can check the broken lines of photo-painted files to avoid a series of problems caused by broken lines. production quality issues.
How does the broken line come about?
1. The fan-out hole routing is too long, resulting in broken wires: After modifying the design file , without using DFM checks , the fabric routing There is no hole punching for a long time , nor is it connected to any other location , resulting in broken wires. If DFM is used to check this Broken line In fact, this broken line can be deleted and canceled.
2. Broken ends of copper wire: No copper optimization was done after the design was completed , removing the residual copper, resulting in broken wires. Design completed Use DFM check after completion to avoid this broken line , the software detects this type of broken wire , you can put this kind of broken line Delete processing.
3. Broken wires in open network: This kind of problem is definitely caused by not doing DRC check, and not using DFM check after light drawing. The emergence of such problems is not only a manufacturability problem caused by broken wires, but more seriously, open circuits, which lead to the failure of the entire batch of products. not available.
What troubles does broken wire bring to production?
4. Open circuit: The board produced by manufacturing negative film, the position covered by dry film is the circuit, and the copper foil without dry film is etched It is the substrate. When there is a broken line in the circuit file, the broken line is not covered by dry film after lamination, exposure and development, and etching will Etch away the copper at the broken wire position , resulting in an open circuit.
2. Short circuit: After etching, if there is a long broken wire, when passing through the grinding machine , because the broken line has no connection with other The broken wires are connected at the same position, so there is no adhesion and they are easy to fall off. When grinding the plate, the broken wires will fall on other wires, causing other wires to Local network short circuit.
3. Delayed production cycle: During the production process, the CAM engineer of the board factory found that the broken line needed to be confirmed with the design engineer. Do you need to connect to other locations? Because the CAM engineer of the board factory only processes the drawings of the photolithography files and will not Connect the designed network at will. If there is any abnormality in the design file, communicate again. , it takes time , if it is a fast delivery product, It will definitely delay the delivery of the product , and communication also has costs.
