Introduction to High Frequency High-speed PCB Board Material Requirements
The rapid progress of the communications industry, the original civilian communications band congestion, high-frequency communications part of the frequency band (military) gradually give way to civilian. Civilian high-frequency communications to obtain extraordinary speed development. Satellite reception, base station, navigation, medical, transportation and other fields to show their strengths.
High confidentiality and high transmission quality require cell phones, automobile power stations, and wireless communications to develop in the direction of high-frequency. High picture quality requires high frequency broadcasting of programs for radio and television transmission. High information transmission requires satellite communications, microwave communications, and fiber optic communications to be high-frequency.
Computer technology to increase the processing capacity, information storage capacity increases, the urgent need for high-speed information transmission. Therefore, electronic information products, high-frequency, high-speed PCB board put forward the requirements of high-frequency characteristics.
A. High frequency and High-speed PCB Board Material Requirements
a, low dielectric constant (Low Dk): low dielectric constant can enhance the signal transmission speed;
b, Low dissipation (loss) factor (Low Df): as the frequency increases, the loss of strength will also increase, so high-frequency and high-speed communications are mostly designed and produced using low dissipation factor materials;
c, Conductor surface roughness
The higher the signal frequency, the more obvious the skin effect, so the signal transmission conductor surface is flatter and better.
εeff: dielectric constant.
tanδ: Dissipation factor.
c: Light speed.
B. Dielectric Constant: Dk or Er(ε)
The amount of electrostatic energy that can be stored per unit volume of insulating material, per unit of potential gradient. How much electrostatic energy can be stored per unit of potential gradient." The "dielectric constant" (or transmittance) of the insulating material should be as small as possible. Currently the board to Teflon (PTFE), in the 1MHZ frequency dielectric constant of 2.5 is the best, FR-4 is about 4.7. circuit board can be regarded as a capacitive device, wire signal transmission, there will be part of the energy is accumulated by the circuit board, resulting in transmission delays, the higher the frequency of the delay is more pronounced.
C. Dissipation Factor: Df
A measure of the functional loss of alternating current. A property of insulating materials (resins). It is proportional to the loss of electrical work seen, and inversely proportional to the frequency of the cycle (f), the square of the potential gradient (E2), and the unit volume.
D. Conductor Surface Roughness
Conductor surface roughness morphology on the resistance to heat, resulting in the loss of signal energy, both for the conductor loss. The higher the frequency, the shorter the wavelength, the signal traveling between the conductor, will only be concentrated on the surface of the conductor, that is, the "skin effect". The flatter the surface roughness is, the more favorable the signal transmission, the PCB layer followed by the strength of the conductor surface roughness. The higher the surface roughness of the conductor, the larger the adhesion area between the resin and the conductor, and the higher the adhesion strength.
E. Copper Foil
a, According to the production process can be divided into:
a) Electrolytic copper foil (Electrodeposited copper foil).
Advantages: Cheap; various sizes and thicknesses;
Disadvantages: Poor ductility; very high stress can not be bent and easily broken.
b) Calendered copper foil (Rolled-wrought copper foil).
Advantages: High ductility, FPC use dynamic environment, excellent reliability; low surface prism, for Microwave electronic applications is very favorable;
Disadvantages: Poor adhesion to the substrate; high cost; limited width due to technical problems.
b, According to the performance of copper foil can be divided into:
a) High temperature extensible copper foil with reverse side treatment;
b) Double-sided treatment copper foil with ultra-low diamond wire;
c) Ultra-thin copper foil standard electrolytic copper foil.
Shenzhen Xinchenger Electronics Co., Ltd. is a professional 2-36 layers high frequency PCB circuit board manufacturers, can be expedited production of PCB boards, high frequency boards, special circuit boards, microwave RF boards, antenna boards and other products, standing Rogers, TACONIC, F4B, TP-2, FR-4 and other boards, the dielectric constant of 2.2-10.6 ranging. Please contact us if you have any demand.
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