Common PCB line width corresponding to current

General PCB routing line width considers two problems: 

- One is the size of the current, if the current is large, the line can not be too thin; 

- The other is to consider the actual making capacity of the board factory. 

If the current is small, the line can be thin, but if too thin, some PCB board factory may can not to produce, or even if it can be produced, but the defect rate rises, so to consider the problem of the board factory.

I. The width of the power line and the ground line is preferably as wide as possible, and the ground line is wider than the power line

These relationships are: ground line > power line > signal line, usually the width of signal line is 0.2-0.3mm (8-12mil), the thinnest width is 0.05-0.07mm(2-2.8mil), and the power line is 1.2-2.5mm (48-100mil).
 

II. PCB commonly routing line width and via selection

2.1 Line width 8/8mil, via 12mil, most PCB manufacturers can produce, and the production cost is low.

2.2 Line width 6/6mil, via 12mil, most PCB manufacturers can produce, and the production cost is low.

2.3 Line width 4/4mil, via 8mil, more than half of the PCB manufacturers can produce it, but it will be a little more expensive.

2.4 Line width 3.5/3.5mil, via 8mil, there are fewer PCB manufacturers and are a little more expensive.

2.5 Line width 2/2mil, via 4mil, many PCB manufacturers can not produce it, and this price is the highest.

According to the density designed of PCB set the line width, if the density is small, the line width is a little larger, the density is larger, and the line width is a little smaller.

III. Current corresponds to the line width

I=K* T^0.44*A ^0.47

K is the correction coefficient, and generally the copper clad wire takes 0.024 in the inner layer and 0.048 in the outer layer;

T is the maximum temperature rise, the unit is ℃;

A is the cross-sectional area of the copper-clad wire in mil (not mm);

I is the maximum current, the unit is A.