How To Calculate PCB Trace Width/space And Current In PCB Design
When we design PCB, it’s necessary consider how to calculate PCB trace width/space for the through current.so what is the relationship between PCB trace width and space and current? The following is a brief explanation of this:
The PCB trace width/space and current calculation method is as follows:
1.Calculate PCB trace area,the thickness of the copper foil for most of the PCBcircuit board is 35um. It is multiplied by line width is the section area, and is converted into square millimeter.There is a current density experience value for 15~25 ampere / square millimeter,The flow capacity is obtained by multiplying it by the sectional area.
T is the maximum temperature rise, the unit is centigrade (the melting point of copper is 1060 degrees C).
A is a copper cladding area with a unit of square MIL (not millimeter mm, square mil.).
I is the permissible maximum current, the unit is ampere (AMP)
General 10mil=0.010inch=0.254 can be 1A, 250MIL=6.35mm, 8.3A
2. Data of calculate PCB trace width/space and current
The calculation of PCB current carrying capacity has always been lacking in authoritative technical methods and formulas. Experienced CAD engineers can make more accurate judgments depending on their personal experience.But for a new CAD designer, it is difficult problem.
The current carrying capacity of PCB depends on the following factors: PCB trace width, PCB trace thickness (thickness of copper foil), allowable temperature rise.
As you all know, the PCB trace is wider,the capacity of the carrier is greater.Here, please tell me: assuming that under the same condition, the 10MIL line can withstand 1A, then how much current can be borne by the 50MIL’s walking line, is it 5A? the answer sure is no. Please see the following data from the international authority:
The unit of line width is: Inch (inch =25.4millimetres, 1oz. copper =35 micron thick, 2oz.=70 micron thick, 1OZ=0.035mm.)
3. Experiment of calculate PCB trace width/space and current
In the experiment, we also have to consider the pressure drop caused by the line resistance produced of length of the wire.The tin in the process welding is only to increase the capacity of the current, but it is difficult to control the volume of the tin. 1OZ copper, 1mm wide, general 1-3A galvanometer, you look at the specific length, the pressure drop of the requirements.
The maximum current value should refer to the maximum allowable value under the limit of temperature rise, and the fusing value is the value of the temperature rising to the melting point of the copper. Eg. 50mil 1oz temperature rise 1060 degrees (that is, copper melting point), the current is 22.8A.