PCB Blog - Rogers circuit board dielectric constant

Rogers dielectric sheets are widely used in PCBs with high frequency, high speed and high reliability requirements. With low loss factors, stable dielectric constants, good thermal stability and mechanical properties, these sheets excel in ensuring signal integrity and improving system efficiency.

Rogers PCB materials have a low dielectric constant, typically between 2.2 and 3.5, which means they can maintain signal integrity and minimize signal loss at high frequencies and long distances.

The permittivity constant is the main parameter that reflects the dielectric or polarization properties of piezoelectric materials under the action of an electrostatic field.It is usually used ε To represent.Different types of piezoelectric components have different requirements for the permittivity constant of piezoelectric materials. When the shape and size of piezoelectric materials are constant,the dielectric constant ε Determined by measuring the inherent capacitance CP of piezoelectric materials.

The polarity of polymer materials can be determined based on their permittivity constant. Usually, substances with a relative permittivity constant greater than 3.6 are polar substances; Substances with a relative permittivity constant in the range of 2.8 to 3.6 are weakly polar substances; non-polar substances with a relative permittivity constant less than 2.8.

Relative permittivity constant ε R can be measured using an electrostatic field method: first, test the capacitance C0 of the capacitor when there is a vacuum between the two electrode plates. Then, measure the capacitance Cx using the same distance between the capacitor plates, but adding a dielectric between the plates.

The permittivity constant of common Rogers PCBs

1) RO4003C: 3.38

2) RO4350B: The permittivity constant (Dk: 3.48+/-0.05) has strict tolerance control and low loss characteristics (Df: 0.0037 10GHz).

3) RO5880:5880 sheet is a polytetrafluoroethylene (PTFE) based material with a permittivity constant of 2.2 and a thickness range of 0.003 inches to 0.240 inches. The copper foil thickness of the board can be selected as 0.5oz, 1oz, 2oz, and 3oz. Its dielectric constant has good stability, low loss, good impedance matching, and fast signal transmission speed. At the same time, the mechanical properties of the board are also very good, with characteristics such as high strength, high stiffness, good heat resistance, and chemical corrosion resistance.

4) RO3003: The best resin and special filler were selected, as well as the ED copper material with extremely low copper foil surface roughness (lp). Its permittivity constants at 10GHz and 77GHz were 3.00 (clamp strip line method) and 3.07 (microstrip line differential phase method), respectively. The loss of Ro3003 high-frequency circuit board material is also very low. According to the differential length method of microstrip lines, the insertion loss at 77GHz on 5mil Ro3003 material is only 1.3dB/inch.

The influence of dielectric constant on Rogers PCB

The permittivity constant of Rogers PCB has a significant impact on the performance of a circuit board. Generally speaking, the larger the permittivity constant, the slower the signal transmission speed and the less noise interference. However, the permittivity constant can also affect issues such as capacitance size and signal reflection. Therefore, when designing a PCB, it is necessary to choose appropriate materials based on the usage situation to achieve better circuit performance.

Generally speaking,the permittivity constant is a quantity that characterizes the degree to which a medium attenuates electromagnetic waves.The larger the dielectric constant, the greater the substrate loss,and the stronger the attenuation of electromagnetic waves.

Technical Requirements and Design Considerations

Lamination process: Due to the special characteristics of Rogers dielectric sheets,the lamination process requires precise control of temperature,pressure and time to avoid defects such as delamination and blistering, and to ensure the electrical performance and mechanical strength of the board.

Drilling and Copper Plating: Given the high hardness of Rogers boards, choosing the right drill material and drilling parameters, as well as optimizing the copper plating process, is extremely important to ensure the quality of the vias and electrical continuity.

Signal Integrity Analysis: In the design phase, professional software is required to simulate and analyze the signal path to ensure that when using Rogers dielectric sheets, signal delay, crosstalk and other issues can be effectively controlled to meet the requirements of high-speed signal transmission.

Environmental adaptability: For specific application environments (e.g., high temperature, high humidity, or extreme climatic conditions), Rogers sheets need to be selected based on their characteristics and tested in the appropriate environment to ensure long-term reliability.

Application Areas of Rogers Circuit Boards

Roger's circuit boards are widely used in high-frequency fields such as communications, radio, radar, satellite communications and so on. It has important application value in high frequency signal transmission, microwave devices, antenna design and so on.

As a high-performance high-frequency board material with low dielectric constant and loss factor, Rogers circuit board can provide better performance in high-frequency signal transmission.