How Wide Should Pcb Traces Be

1. PCB trace

Generally, two issues need to be considered in the width of PCB wiring. One is the size of the current. If the current flowing through is large, the wiring cannot be too thin; the other is to consider the actual board making capacity of the board factory. If the current is small, the wiring can be thinner, but if it is too thin, Some PCB board factories may not be able to make them, or they may make them but the defect rate has increased, so the problem of PCB board manufacturers should be considered.

PCB copper thickness is generally divided into 1OZ (35um), 2OZ (70um), 3OZ (105um), the general double-sided board is 1oz; the inner layer of the multi-layer board is generally 1/2oz 1/3oz, the outer layer is 1oz 1/2oz 1/3oz ,

There are two sizes in the PCB, mm and mil, and the conversion relationship is 1mm=39mil.

For example, the allowable current of commonly used IC traces with a width of 10mil and 1OZ is about 675mA, and the allowable current of 8mil and 1OZ is about 550mA. You can refer to the figure below

The width of the power line and the ground line should be as wide as possible, and the ground line is wider than the power line. These relationships are: ground wire>power wire>signal wire, usually the width of the signal wire is 0.2-0.3mm (8-12mil), the thinnest width is 0.05-0.07mm (2-2.8mil), and the power wire is 1.2- 2.5mm (48-100mil). (0.025mm=1mil).

2. Common line width of pcb wiring

(1) Generally, the line width and line spacing are controlled to 8/8 mil, and the via hole is selected to be 12 mil (0.3 mm), which can be produced by most PCB manufacturers, and the production cost is low.

(2) Generally, the line width and line spacing are controlled to 6/6mil, and the via hole is selected to be 12mil (0.3mm), which can be produced by most PCB manufacturers, and the production cost is low.

(3) The minimum line width and line spacing are controlled to 4/4mil, and the via hole is 8mil (0.2mm). More than half of the PCB manufacturers can produce it, but the price will be a little more expensive than the previous one.

(4) The minimum line width and line spacing are controlled to 3.5/3.5mil, and the via hole is 8mil (0.2mm), which can produce fewer PCB manufacturers, and the price will be a little more expensive.

(5) The minimum line width and line spacing are controlled to 2/2mil, and the via hole is selected to be 4mil (0.1mm), which many pcb manufacturers cannot produce. The price of this is the highest, but our company can do it.

(6) Mains live wire and neutral wire: 80-100mil, 12V/24V 20mil~60mil, +5V 20-30mil

, +3V 20-30mil, the wider the GND, the better 20-30mil, the ordinary signal line 10mil-20mil is determined by the density of components

If the line width is set according to the density of the PCB design, the density is small, the line width and line spacing can be set larger, and the density is larger, and the line width and line spacing can be set smaller:

3. Summary:

Common signal line widths and vias are as follows:

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

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

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

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

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

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

Reference via: inner diameter 12mil, outer diameter 20mil

Reference inner diameter 20mil, outer diameter 30mil

4. The current corresponds to the line width

I=K* T^0.44*A^0.47

K is the correction coefficient. Generally, the copper-clad wire is taken as 0.024 when it is in the inner layer and 0.048 when it is in the outer layer;

T is the maximum temperature rise, in °C;

A is the cross-sectional area of the copper clad wire, the unit is mil (not mm, pay attention);

I is the maximum allowable current, the unit is A.

This article is an original article by CSDN blogger "Talking Hair Dryer", which follows the CC 4.0 BY-SA copyright agreement. Please attach the original source link and this statement for reprinting.

Original link: https://blog.csdn.net/qq_52940987/article/details/124570167