a. Rigid PCB, b. Flexible PCB, c. Rigid-Flex PCB1), Rogers: Rogers: RO4003, RO3003, RO4350, RO5880, etc. With the development of 5G millimeter waves, Rogers has also launched a variety of low-loss circuit boards suitable for millimeter waves.RO3000 Series: Based on ceramic filled PTFE circuit materials, models are: RO3003, RO3006, RO3010, RO3035 high-frequency laminates.TMM Series: Composites based on ceramics, hydrocarbons, thermoset polymers, models: TMM3, TMM4, TMM6, TMM10, TMM10i, TMM13i.and many more4), Isola: FR408HR, IS620, IS680, etc.5), Nelco: N4000-13, N4000-13EPSI, etc.Under the condition of frequency change, general substrate materials show a large change in DK and DF values.Especially in the frequency from 1 MHz to 1 GHz, the changes of their DK and DF values ​​are more obvious.For example, the DK value of the general epoxy resin-glass fiber cloth-based substrate material (general FR-4) at the frequency of 1MHz is 4.7, and the DK value at the frequency of 1GHz changes to 4.19.Above 1GHz, the change trend of its DK value is gentle.Its changing trend is that it becomes smaller as the frequency increases (but the change is not large). For example, at l0GHz, the general DK value of FR-4 is 4.15, and the substrate material with high-speed and high-frequency characteristics changes in frequency. In the case of , the change of DK value is small, from 1MHz to 1GHz change frequency, DK is mostly kept in the range of 0.02.Its DK value tends to decrease slightly under different frequency conditions from low to high.The dielectric loss factor (DF) of the general substrate material is affected by the frequency change (especially in the high frequency range), and the change in the DF value is larger than that of the DK.Its change rule tends to increase, therefore, when evaluating the high-frequency characteristics of a substrate material, the focus of its investigation is the change of its DF value.Substrate materials with high-speed and high-frequency characteristics, in terms of changing characteristics at high frequencies, there are two distinct types of general substrate materials: one is that with the change of frequency, its (DF) value changes very little. .Another type is similar to the general substrate material in the range of change, but its own (DF) value is lower.Choosing a PCB board must strike a balance between meeting design requirements, mass production, and cost.Simply put, design requirements include both electrical and structural reliability.Usually when designing very high-speed PCB boards (frequency greater than GHz) this board problem is more important.For example, the commonly used FR-4 material has a large dielectric loss Df (Dielectricloss) at a frequency of several GHz, which may not be applicable.For example, the 10Gb/S high-speed digital signal is a square wave, which can be regarded as the superposition of sine wave signals of different frequencies.Therefore, 10Gb/S contains many different frequency signals: 5Ghz fundamental signal, 3rd order 15GHz, 5th order 25GHz, 7th order 35GHz signal, etc.Maintaining the integrity of the digital signal and the steepness of the upper and lower edges is the same as the low-loss and low-distortion transmission of RF microwave (the high-frequency harmonic part of the digital signal reaches the microwave frequency band).Therefore, in many respects, the requirements for PCB material selection for high-speed digital circuits are similar to those for RF microwave circuits.Among the above factors, the running speed of high-speed digital circuits is the main factor for PCB selection. The higher the speed of the circuit, the smaller the selected PCBDf value should be.Boards with medium and low losses will be suitable for 10Gb/s digital circuits; boards with lower losses will be suitable for 25Gb/s digital circuits; boards with ultra-low loss will be suitable for faster high-speed digital circuits, whose rate can be 50Gb /s or higher.Electronic kaleidoscope platform self-operated: Xilinx ALTERA ADI TI ST NXP Micron Samsung Hynix memory chips and other electronic components of more than 100 brands, accept BOM list, lack of materials, unpopular, discontinued, and foreign embargoed device business to China!