Common mistakes in PCB schematic design

 

In the PCB design, wiring is an important step to complete the product design. It can be said that the previous preparation work is done for it. In the whole PCB, the wiring design process is the highest, the trick is the finest, and the workload is the largest. PCB wiring has single-sided wiring, double-sided wiring, and multilayer wiring. There are also two ways of wiring: automatic routing and interactive wiring. Before automatic routing, you can use interactive pre-wired lines that are more demanding. The edges of the input and output should avoid adjacent parallel to avoid reflection interference. Grounding should be added when necessary. The wiring of two adjacent layers should be perpendicular to each other, and parasitic coupling is easy to occur in parallel.

 

(1) The ERC report pin has no access signal:

  1. I/O attributes are defined for the pins when the package is created;
  2. The inconsistent grid attribute is modified when the component is created or placed, and the pin is not connected to the line;
  3. When the component is created, the pin direction is reversed and must be connected to the non-pin name.

(2) The component runs outside the drawing boundary: no component is created in the center of the component library chart paper.

(3) The created project file network table can only be partially transferred to pcb: when the netlist is generated, it is not selected as globa;

(4) Never use annotate when using a multi-part component created by yourself.

pcb schematics

  1. Common errors in PCB:

 

(1) The report NODE was not found when the network was loaded:

  1. The components in the schematic use packages that are not in the pcb library;
  2. The components in the schematic use packages with inconsistent names in the pcb library;
  3. The components in the schematic use the inconsistent package of the pin number in the pcb library. For example, the triode: the pin number in sch is e, b, c, and the pcb is 1, 2, 3.

 

(2) It is always impossible to print to one page when printing:

  1. The pcb library is not created at the origin;
  2. Move and rotate the component multiple times, there are hidden characters outside the pcb board. Select to display all hidden characters, reduce the pcb, and then move the characters into the boundary.

 

(3) The DRC reporting network is divided into several parts:

Indicates that the network is not connected. Look at the report file and use the option CONNECTED COPPER to find it.

Also remind friends to use WIN2000 as much as possible to reduce the chance of blue screen; export files several times to make new DDB files, reduce file size and PROTEL zombie opportunities. If you are more complicated, try not to use automatic routing.

 

The routing rate of automatic routing depends on a good layout, and the wiring rules can be preset, including the number of bending of the traces, the number of vias, the number of steps, and the like. Generally, the exploratory warp line is firstly connected, and the short lines are quickly connected, and then the labyrinth wiring is performed. First, the wiring to be cloth is optimized for the global routing path, and the laid line can be disconnected as needed, and try again. Wiring to improve overall results.

 

For the current high-density PCB design, it has been felt that the through-hole is not suitable. It wastes a lot of valuable wiring channels. To solve this contradiction, blind hole and buried hole technology have emerged, which not only completes the function of the via hole. It also saves a lot of wiring channels to make the wiring process more convenient, smoother and more perfect. The PCB board design process is a complicated and simple process. To master it well, it also needs extensive electronic engineering design. People can experience their true feelings when they go to their own experience.