PCB assembly china grounding design

Grounding is an important method for controlling interference in electronic devices. If grounding and shielding can be combined correctly, most interference problems can be solved. In PCBA assembly grounding design, the following points should be noted:

1. Correctly choose between single point grounding and multi-point grounding

In low-frequency circuits, the operating frequency of the signal is less than 1MHz, and the influence of inductance between its wiring and devices is relatively small. However, the circulating current formed by the grounding circuit has a greater impact on interference, so a single point grounding should be used. When the operating frequency of the signal is greater than 10MHz, the ground impedance becomes very large. At this time, the ground impedance should be minimized as much as possible and multiple grounding points should be used nearby. When the operating frequency is between 1-10MHz, if a single point grounding is used, the length of the ground wire should not exceed 1/20 of the wavelength. Otherwise, the multi-point grounding method should be used.

2. Separate digital circuits from analog circuits

PCBA assembly have both high-speed logic circuits and linear circuits, so they should be separated as much as possible, and the ground wires of the two should not be mixed. They should be connected to the ground wire of the power supply terminal separately. Try to increase the grounding area of linear circuits as much as possible.

3. Try to thicken the grounding wire as much as possible

If the grounding wire is very thin, the grounding potential will change with the current, causing the timing signal level of electronic devices to be unstable and the anti noise performance to deteriorate. Therefore, the grounding wire should be thickened as much as possible so that it can pass through the allowable current of the printed circuit board. If possible, the width of the grounding wire should be greater than 3mm.

4. Form a closed loop with the grounding wire

When designing the grounding system of a printed circuit board consisting only of digital circuits, making the grounding wire a closed loop can significantly improve its noise resistance. The reason is that PCB assembly china has many integrated circuit components, especially when encountering high power consuming components. Due to the limitation of the thickness of the grounding wire, a large potential difference will be generated on the ground junction, causing a decrease in noise resistance. If the grounding structure is formed into a loop, the potential difference will be reduced, and the noise resistance of electronic devices will be improved.

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