The Factors That We should Consider About Power Processing In PCB
The processing of the power plane plays an important role in PCB design.
In a complete PCB design project, usually the power supply process determines the success rate of 30%-50% of the project
Today, let’s talk about the basic elements that we should consider in the power plane processing during the PCB design process.
1 When doing power processing, we should first consider its current carrying capacity,which includes two aspects:
a) Whether the power line width or the width of the copper is sufficient to consider the power line width
The first step is to understand the copper thickness of the layer on which the power signal is processed.
However, under the conventional process, the outer thickness of the PCB (TOP/BOTTOM layer) is 1OZ (35μm),
and the inner copper thickness is 1OZ or 0.5OZ according to the actual situation
For 1OZ copper thickness, under normal conditions, 20mil can carry about 1A current.
But, for 0.5OZ copper thickness, under normal circumstances, 40mil can carry about 1A current
b) Whether the size and number of holes in the layer change meets the current flow capability of the power supply
First, we must understand the flow capacity of a single via. And also a single 10 mil via can carry a current of 1 A
so if the power supply is 2 A when designing, at least 2 or more vias should be used when using 10 mil vias for hole punching.
2 Secondly, we should consider the power path, which includes the following two aspects :
a) The power path should be as short as possible.If it is too long, the voltage drop of the power supply will be serious.
And, if the voltage drop is too large, the project will fail.
b) The power plane is divided as much as possible, and slender and dumbbell-shaped segments are not allowed.
c) When dividing the power supply, the distance between the power supply and the power plane should be kept as close as possible to 20 mil.
If it is in the BGA part, the distance of 10 mil can be partially maintained. However, if the distance between the power planes is too close, there may be a risk of short circuit.
d) If the power supply is treated in an adjacent plane, it is necessary to avoid parallel processing between the copper or the traces.
This is mainly to reduce the interference between different power supplies, especially between power supplies with large voltage differences.
The overlapping problem must be managed to avoid. If it is difficult to avoid, consider adding the interlayer in the middle.