1. The signal line that needs to be impedance should be set in strict accordance with the line width and line spacing calculated by the stack. For example, radio frequency signal (normal 50R control), important single-ended 50R, differential 90R, differential 100R and other signal lines, the specific line width and line spacing can be calculated by stacking (pictured below).

2. The designed line width and line spacing should consider the production process capability of the selected PCB production factory. If the line width and line spacing is set to exceed the process capability of the cooperating PCB manufacturer during the design, unnecessary production costs need to be added, and the The design cannot be produced. Generally, the line width and line spacing are controlled to 6/6mil under normal circumstances, and the via hole is 12mil (0.3mm). Basically, more than 80% of PCB manufacturers can produce it, and the production cost is the lowest. The minimum line width and line spacing is controlled to 4/4mil, and the via hole is 8mil (0.2mm). Basically, more than 70% of PCB manufacturers can produce it, but the price is slightly more expensive than the first case, not too expensive. The minimum line width and line spacing is controlled to 3.5/3.5mil, and the via hole is 8mil (0.2mm). At this time, some PCB manufacturers cannot produce it, and the price will be more expensive. The minimum line width and line spacing is controlled to 2/2mil, and the via hole is 4mil (0.1mm, at this time, it is generally HDI blind buried via design, and laser vias are required). At this time, most PCB manufacturers can’t produce it, and the price is the most expensive of. The line width and line spacing here refer to the size between elements such as line-to-hole, line-to-line, line-to-pad, line-to-via, and hole-to-disk when setting rules.

3. Set rules to consider the design bottleneck in the design file. If there is a 1mm BGA chip, the pin depth is shallow, only one signal line is needed between the two rows of pins, which can be set to 6/6 mil, the pin depth is deeper, and two rows of pins are required The signal line is set to 4/4mil; there is a 0.65mm BGA chip, which is generally set to 4/4mil; there is a 0.5mm BGA chip, the general line width and line spacing must be set to 3.5/3.5mil; there is a 0.4mm BGA Chips generally require HDI design. Generally, for the design bottleneck, you can set regional rules (see the end of the article [AD software to set ROOM, ALLEGRO software to set regional rules]), set the local line width and line spacing to a small point, and set the rules for other parts of the PCB to be larger for production. Improve the qualified rate of PCB produced.

4. It needs to be set according to the density of the PCB design. The density is smaller and the board is looser. The line width and line spacing can be set to be larger, and vice versa. The routine can be set according to the following steps:

1) 8/8mil, 12mil (0.3mm) for via hole.

2) 6/6mil, 12mil (0.3mm) for via hole.

3) 4/4mil, 8mil (0.2mm) for via hole.

4) 3.5/3.5mil, 8mil (0.2mm) for via hole.

5) 3.5/3.5mil, 4mil for via hole (0.1mm, laser drilling).

6) 2/2mil, 4mil for via hole (0.1mm, laser drilling).