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How To Ground A PCB Board?

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You might not know how to ground a PCB board? Are you looking for guidelines to ground a PCB board? If yes, then you came to the right place. We will explain the methods and rules of grounding a PCB board. It is imperative to have information on PCB grounding, especially for those who are new in this field. To know about grounding rules in a printed circuit board, one needs to know about the types of grounding so that no confusion or difficulty can be overcome while performing a grounding activity. Grounding in PCB is essential if you want its correct functionality and results. Keep reading this article if you want to know how to ground a PCB board and what might be the methods and rules for doing so.

Types of grounding:

Every PCB has a different grounding system. It is essential to know about different types of grounding in PCBs so that you can work on every PCB that comes to you. Following are some various types of grounding in PCBs:

  • Power Ground:

The power ground is common for both alternating current and direct current voltages. The ground completes the circuit. Without the ground, the circuit loop is not complete, and the current stops flowing. The ground pin is connected to the components that may have a link to the ground. In this way, all the parts having a connection to the ground are connected to the ground. The power grounding system usage is in large electrical power systems and electronics. Technically, the grounding connections are earthed by an earthing rod or an earthing mesh.  

  • Signal Ground:

Signal ground is based on analog signals or digital signals. Sometimes, power grounds and signal grounds are equal, but sometimes signals present in the circuit use different grounding connections to return a signal. In this way, they have a specific grounding for the signals. The signal ground can be found in sensitive equipment and measuring instruments.

  • Virtual Ground:

Virtual grounds are mostly found in operational amplifiers (Op-Amp). Virtual ground does not directly connect to the ground; it only matches the ground's potential. Virtual ground analyzes and tests the functionality of the operational amplifiers.

  • Surge and Lightning Protection Ground:

A solid ground connection is required for dissipating high currents in Surge Protection Ground as well as Lightning Protection Ground. Since they have a very low resistance, they have a very high current in them. Due to this, they are welded to the steel of the building and earthed by numerous earth rods and earth mesh. To avoid any voltage difference between earth terminals, equipotential bonding is set up between Electrical Power Earth and Lightning Protection Ground.

  • Grounding in Electric Power System:

Grounding in an electrical power system varies from country to country because each country has its own rules, regulations, and practices. But the main and common purpose that every country has is to provide safety while working on PCB. They have two-letter codes. The first letter indicates earthing arrangement to the power source; for example, TT means Direct connection to the earth, etc.

  • Floating Ground:

When the system does not have a solid ground connection, the floating ground connection can be used. In this way, the voltage in-ground terminals and conductors can not be determined. If there is a potential break in the system, that is considered a faulty system. Isolation transformers, having low voltage supplies and testing instruments, are used to separate the low voltage ground from the ground system to improve safety and protection. By connecting the ground to the low voltage, it avoids the grounding of the current from the main supply. In this way, it provides safety and protection on the low voltage side.

PCB

Grounding methods:

There are a few methods that one should keep in mind while grounding a printed circuit board. Abide by these methods will aid you in successfully grounding the ground terminals. These methods can vary from design practice and circuit application. 

    1. Ground Traces:

In old and simple PCBs, all the components that connect to the ground are linked together from common ground traces.

    1. Common Ground Plane:

The common ground plane is the most common practice in PCB designing. The empty spaces present in the printed circuit board, which is not part of any components or traces, are covered by the ground. By this method, the thermal characteristics of the PCB are significantly improved, and it also aids in reducing electromagnetic interference.

    1. Dedicated Ground Layer:

PCBs having multilayers uses a dedicated ground layer. It is present in complex PCBs having three or more layers. Every component present in the complex PCB is connected to the ground. 

    1. Grounding Electrical Power Systems:

In electrical power systems, due to their low resistance and high current, multiple connections are involved, which all lead to one ground connection. All the connections are linked to an earth bus bar, which is connected to an earth conductor, which is further connected to an earth rod or earth mesh. The bus bar collects all the earth wires to a common point. To provide better grounding, the resistance of this point must be less than or equal to 5 Ohms. The Earth bus bar is connected to earthing arrangement through a high gauge wire.

    1. Equipotential Earthing or Grounding:

Equipotential means that every element used in the grounding system must have equal potential. This can be achieved by connecting the framework of equipment, metal pipes, and all earthing arrangements in the system. In this way, there will be no potential difference between any conductive parts as all will have the same potential. This will prevent from getting a shock due to a fault.

Grounding rules:

While performing grounding activities, some rules must be kept in mind. These rules will help in guiding you to perform better. If these rules are not followed, the result will not be as good as one may have thought. Following are some rules and regulations for PCB grounding:

  • Leave nothing unattached:

If there is an open or empty space in the printed circuit board, fill it with copper or connect it to the ground plane. In this way, all the paths will be covered, and this will help the signals move around more efficiently. Try not to leave anything unattached.

  • Never slice up your ground layer:

Most users work on complex PCBs having multiple- layers. This works efficiently until and unless they do not route traces on the dedicated ground layer. Once they do, they might create a ground current loop. So, try not to slice up your ground layer.

  • Always provide a common ground point:

An electronic power system, whether it is a single or multi-layered system, always needs a common ground point. This may be the metal frame on a framework or a dedicated ground layer on the PCB. The common ground point can also be referred to as star grounding. 

  • Minimize service vias:

Minimize your series vias on your ground paths and send component grounds directly to your dedicated ground plane. Impedance and vias are directly proportional to each other; if there are more vias, you will have to deal with more impedance. This is for transient currents that can easily turn an impedance into a potential difference.

  • Grounding before routing:

Try to ground first and then start routing. If the PCB is not grounded properly, this can put your entire operation at risk. If you properly design your ground first, this can be the foundation of your entire serving process. 

  • Know where your currents are going:

Most designers only watch the pathway of the signals; they do not observe the paths of the current. Although every signal has a return path through the ground and every signal has the same current overall, it can affect the stability of the power. To avoid this, try to use Kirchhoff's Current Law.

  • Plan for dynamic variance between grounds:

Always plan for dynamic variance between grounds, especially when working on applications that require long-distance cables. For such situations, try using low voltage differential signals, optical isolators, and common-mode chokes.

  • Mind your mixed-signal floor planning:

The analog to digital converter and digital to analog converter must be kept separate. When you are designing a floor plan for your signals, be sure to keep these areas separated. An analog to digital converter can be used to pass the signals to other parts of the printed circuit board.

Conclusion:

Grounding a printed circuit board requires patience and effort as it is not something a beginner can do. A beginner can gain experience if they want to be professionals in the expertise of grounding a printed circuit board. We mentioned all the points related to grounding a printed circuit board. One needs to understand its types, methods, and rules if one wants to perform grounding activity with accuracy. We hope that this information was a real help to you, and if you keep this information in mind, you will be a professional one day.

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