Blog

HomePCB knowledgeTechnologyAnalyze the relationship between PCB circuit width and current.

Analyze the relationship between PCB circuit width and current.

Analyze the relationship between PCB circuit width and current.

Relationship between line width of PCB board and current

PCB manufacturers often consider the problem of PCB wire width and wire spacing when designing documents. What is the relationship between PCB wire width and current?Here is a brief explanation:

I. calculation method is as follows:

First, the cross-sectional area of Track is calculated. The copper foil thickness of most PCB plates is 35um, which is the cross-sectional area when multiplied by the line width.There is an empirical value for current density between 15 and 25 amperes per square millimeter.You multiply that times the area and you get the volume.

 

T to the maximum temperature rise, the unit for degrees Celsius (copper melting point is 1060 ℃)

A is copper-clad cross sectional area in square MIL(not mm, note square MIL.)

I is the allowable maximum current in units of amp.

Generally, 10mil=0.010inch=0.254, which can be 1A, 250MIL=6.35mm, which is 8.3A

Ii. Data

The calculation of PCB current-carrying capacity is always lack of authoritative technical methods and formulas. Experienced CAD engineers can make accurate judgment based on their personal experience.But for the CAD novice, it is not a problem.

PCB’s current carrying capacity depends on the following factors: line width, line thickness (copper foil thickness), allowable temperature rise.It is well known that the wider the PCB’s routing, the greater its current carrying capacity.Here, please tell me: assuming that under the same conditions, the routing of 10MIL can withstand 1A, then how much current can the routing of 50MIL, is it 5A?The answer, of course, is no.See the following data from international authorities:

The units of wire width are: Inch (Inch =25.4millimetres mm), 1oz. Copper =35 microns, 2oz.=70 microns, 1oz =0.035mm, 1mil.=10-3inch.

Iii. Experiment

In the experiment, the pressure drop caused by the wire resistance caused by the length of the wire should also be considered.The solder is only used to increase the current capacity, but it is difficult to control the volume of tin.1OZ copper, 1mm wide, usually 1-3a galvanometer, depending on your line length and pressure drop requirements.

The maximum current value should be the maximum allowable value under the limit of temperature rise.Eg. 50mil 1oz temperature rise 1060 degrees (i.e. copper melting point), current is 22.8A.