With PCBs getting increasingly complex and small sized by the day, they need to be designed considering various aspects of the application, and impedance is one of them. This is especially because high speed transmission and a high signal strength are a common requirement in most applications. At high frequencies, the path between transmission and reception points needs to be clear for successful transmission of signals, which in case of impedance may get distorted. Impedance is a resultant combination of capacitance and inductance which is produced against the flow of current in a circuit. Impedance control us necessary as it may become uncontrolled and vary through the board. A controlled impedance is essentially relevant when high-frequency signals propagate through the PCB transmission lines and hence helps in achieving good signal integrity in printed circuit boards. Designing a printed circuit board is a vital step for effective impedance control trace routing. This post will help you in understanding the importance of impedance control in printed circuit boards and also gives a brief detail about PCB designing for impedance control.
What is Impedance Control in PCBs?
In high frequency applications, impedance values must be controlled throughout the board and the design must ensure that high frequency signals would traverse through traces with controlled impedance. The basic function of a PCB trace is to generate signal power and transfer it from the driver device to the receiving device. This signal power needs to be spread throughout the length of the trace. Impedance control in PCBs ensures there is seamless signal transmission from source to destination.
Importance of Impedance Control in PCB Designs
In high-frequency applications like smartphones, computers, etc., controlling the impedance is very essential to protect the transferred data from getting damaged and it also helps in providing a clear signal to all the devices. The designs of printed circuit boards in high-frequency applications are of high complexities and hence providing impedance control in it is very important. The points given below describe the importance of impedance control in PCB designs more clearly. Impedance control achieves the following:
- Provides a clear signal throughout the complete board.
- Controls the flow of electricity in the printed circuit board.
- Controls and regulates the electrical flow as per the device requirement.
- Impedance control eliminates the impact caused on signal integrity due to complex designs and high frequencies.
- To generate maximum signal integrity, matching impedances on printed circuit boards is very important.
Design Recommendations for PCBs to Get a Good Impedance Control
As we have already understood why impedance control is important, let’s now see how we can achieve it by simply understanding the required design of a printed circuit board. Controlling the impedance on a PCB for a signal to route through sensitive traces depends upon the following factors:
- Spacing: In any PCB design, the most important factor is the space between components. Some PCBs may require very complex designs due to the high-frequency requirement but the vertical spacing between the signal trace and the ground planes is considered an important factor for matching impedance.
- Trace Geometry of Board: Impedance calculation essentially depends upon the geometry of the PCB trace. Hence it is important to choose the cross-section volume of copper carefully to maintain the width and thickness of the copper layer.
- Dielectric Material in PCBs: Impedance needs to be calculated, and varies with materials used for the PCB. The dielectric material that is the Dk value of non-conductive material on a printed circuit board should match with the traces’ geometry because it also impacts the impedance calculation.
The information given above may help you in understanding the importance of impedance control in PCBs. If you are looking for a manufacturer that can provide you with reliable printed circuit boards with good impedance control for your projects then you must know about Rigiflex Technology, Inc. Rigiflex Technology in the USA has established its position as a printed circuit board manufacturer for complex requirements.
