PCBA Tech - Precautions for PCBA processing power supply graphic design

As the main force in the electronics industry, PCBA processing plants play an important role in the development of the electronics industry. Professional PCBA processing plants are constantly updating and iterating. The following introduces the precautions of the power supply plane design in the patch.

The processing of PCBA processing power plane plays a key role in its design. In the detailed PCB design, the power supply solution can determine that 30% of the new project is less than or equal to 50% of the qualified rate, so what should be paid attention to in the plane processing of the power supply?

1. In order to solve the problem of switching power supply, the first thing to consider is its ability to carry current, which includes two levels.

1. The width of the power plug or the total width of the copper sheet is sufficient. In order to consider the width of the power plug, the copper thickness of the layer where the switching power supply signal is analyzed must be grasped. Under the basic process conditions, the copper thickness of the PCBA surface layer (upper and lower layer) is 1 oz (35 Um), and the copper thickness of the inner layer can be guaranteed to be 1 oz or 0.5 OZ according to the specific situation. For 1oz copper thickness, under basic conditions, 20mil can withstand a load of 1A, and the upper and lower currents are 0.5 ounces of copper thickness. Under basic conditions, 40 ml can withstand a load of 1A.

2. Whether the size and number of holes in the switch layer take into account the working capacity of the commercial current flow of the switching power supply. First of all, the load-bearing capacity of a single hole must be mastered. Under the basic conditions, the temperature is 10 degrees.

A 10ml through hole alone can withstand a current of 1A. Therefore, if the switching power supply is a 2A current when formulating a PCBA design plan, at least 2 holes should be made when using 10 MIL size openings and changing layers. Generally speaking, when designing the PCB, you will consider the safe passage of the switching power supply to perforate more holes to keep a small margin.

2. The relative path of switching power supply should be considered, and the following two levels should be considered in practice.

1. The relative path of the switching power supply should be as short as possible. If it goes too long, the voltage drop of the switching power supply will be serious, and the voltage drop will cause the new project to fail.

2. The plane cutting of the power supply should be maintained as much as possible, and the cutting of long bars and barbells should not be allowed.

3. When the switching power supply is divided, the division distance between the switching power supply and the power plane should be kept at 20 milliliters as much as possible. If in some BGAs, the 10ml pitch can be partially maintained, if the power plane is too close to the plan view, there will be a risk of short-circuit failure.

4. If the switching power supply is solved in the adjacent scheme, the copper coating or parallel surface wiring must be reduced as much as possible. The key is to reduce the dry deflection between different switching power supplies, especially in some switching power supplies with a large working voltage distance. The overlap of the power plane must be prevented. In unavoidable circumstances, the geological structure of the middle distance can be considered.

3. When splitting the switching power supply, try to reduce the cross-cutting of adjacent power lines. When the data signal is cut off (the bright red power line has a cross-cutting condition), the lack of continuous characteristic impedance in the reference scheme will cause a sudden change in the characteristic impedance, resulting in electromagnetic interference and crosstalk problems. In the high-speed design scheme, the cross-cutting branch has great harm to the quality of the data signal.

Therefore, the PCBA power supply graphic design is a very important link, and it is also the basic factor for the successful approval of the PCBA processing plant.