How big is the PCB circuit board design line width spacing rule setting

How big is the PCB circuit board design line width spacing rule setting

For many new entrants, it is not clear what the line width of the PCB circuit board should be set to. The editor of the Oneseine PCB Factory will explain here.

For the setting of the wiring width of the PCB circuit board, two issues should be considered:

One is the amount of current flowing. For example, for the power line, the current flowing through the circuit needs to be considered. If the current flowing through is large, the wiring cannot be too thin.

Actual measurement: current carrying capacity of PCB circuit board traces and vias

The second is to consider the actual board manufacturing capacity of the circuit board factory. If the required current is very small (such as a signal line), it can be thinner. Sometimes the PCB circuit board area is small and the components are too many, so you want to make the wiring as thin as possible, but if it is too thin, the circuit board factory may not be able to make it, or it can not be made but the defect rate increases. This can be confirmed with the circuit board factory. As far as I know, the line width is 0.2mm and the line spacing is 0.2mm, which can be done by ordinary circuit board manufacturers. The line width of 0.127mm is not always possible. The industry’s minimum line width standard should be 0.1mm. The follow-up may be more detailed with the development of technology.

As for the size of the vias, you can also directly confirm with the circuit board manufacturer. After all, even if you use small-aperture vias to design a PCB circuit board, the circuit board manufacturer can’t do it, or can do it but it’s not expensive. As far as I know, the outer diameter is 0.5mm and the inner diameter is 0.3mm. Basically all board manufacturers can do it.

1. The PCB circuit board needs to be impedance signal lines, which should be set strictly according to the line width and line distance 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 .

, The designed line width and line spacing should consider the production process capability of the selected circuit board manufacturer. If the line width 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. Under normal circumstances, the line width and line spacing are controlled to 6/6mil, 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 cannot 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 pad.

3. Set rules to consider the design bottleneck in the design file. If there is a 1mm BGA chip, the pin depth is shallower, only one signal line is needed between the two rows of pins, which can be set to 6/6mil, 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 for setting methods), set the local line width and line spacing to be small, and set the rules for other parts of the PCB to be larger in order to facilitate production and improve the qualified rate of PCBs.

4. It needs to be set according to the density of the PCB circuit board 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.

②6/6mil, 12mil (0.3mm) for via hole.

③4/4mil, 8mil (0.2mm) for via hole.

④3.5/3.5mil, 8mil (0.2mm) for via hole.

⑤3.5/3.5mil, 4mil for via hole (0.1mm, laser drilling).

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