Impedance Controlled PCB
Impedance control is matching PCB trace dimensions and locations with the properties of the substrate material to make sure that the strength of a signal traveling along a trace is within a required range. It consists in measuring the impedance of certain traces when the PCB is manufactured and making sure they are within the limits given by the designer.
The impedance of a PCB line is determined by its inductance and capacitance inductance, resistance and conductance. The main factors affecting the impedance of the PCB line are the width of the copper wire, the thickness of the copper wire, the dielectric constant of the dielectric, the thickness of the dielectric, the thickness of the pad, the path of the ground and the surrounding lines, the impedance of the PCB ranges from 25 to 120 ohms.
Traces and slabs constitute the control impedance. PCBs are often constructed in multiple layers and the control impedance can be used in different ways. However, whichever method is used, the impedance value will be determined by its physical structure and electronic characteristics.
Width and thickness of the signal trace height of the core or pre-filled material on both sides of the trace Configuration of traces and slabs Insulation constant of core and pre-filled material.
As circuit designs push the boundaries of higher speeds and frequencies, precise control of impedances within PCBs has become critical to ensure reliable signal transmission and minimize signal degradation issues. Impedance mismatches between traces, components and cables can result in signal reflections, ringing, crosstalk and electromagnetic interference (EMI) that reduce performance. Impedance controlled PCBs apply techniques throughout the design and manufacturing process to carefully match the impedances of traces and components, optimizing signal integrity for high speed signals.
Impedance controlled PCBs maximize signal quality in high speed circuits through material selection, layout optimization, simulation, prototyping, DFM and precision manufacturing—providing a comprehensive solution to mitigate signal integrity issues and optimize performance within constraints.
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