Microwave Tech - Factors in choosing high-frequency PCB or high-speed PCB materials

What are the factors to choose high-frequency PCB or high-speed PCB material?

1. Manufacturability of high-frequency PCB or high-speed PCB materials

For example, the performance of multiple pressing, temperature performance, etc., resistance to CAF/heat resistance, mechanical toughness (stickiness) (good reliability), and fire rating.

RO4350B and low roughness copper foil loss measured comparison

2. Various properties of high-frequency PCB or high-speed PCB materials that match the product

The performance of high-quality PCB materials is: low loss, stable Dk/Df parameters, low dispersion, small variation coefficient with frequency and environment, PCB material thickness and glue content tolerance (good impedance control), if the trace is long, consider low Roughness copper foil. In addition, the design of high-speed circuits requires simulation in the early stage, and the simulation results are the reference standard for the design. "IPCB (High Speed/Radio Frequency) Laboratory" has solved the performance problem of inconsistent simulation results and testing. It has done a lot of simulation and actual testing closed-loop verification, and can achieve the same simulation and actual measurement through a unique method.

3. Timely availability of high-frequency PCB or high-speed PCB materials

Many high-frequency PCB or high-speed PCB materials have a very long procurement cycle, even 2-3 months; except for the conventional high-frequency board RO4350B, RO4003C, Rogers 5880, which is in stock, many high-frequency boards need to be provided by customers. Therefore, high-frequency plates need to communicate well with the manufacturer in advance and prepare the materials as soon as possible.

4. Cost factor of high-frequency PCB or high-speed PCB material

It depends on the price sensitivity of the finished products for PCB applications, whether it is a consumer product, or a communication, medical, industrial, or military application.

5. Applicability of laws and regulations for high-frequency PCB or high-speed PCB materials, etc.

It must be integrated with the environmental protection regulations of different countries to meet the requirements of RoHS PCB and halogen-free PCB.

6. Considering the Df of high-frequency PCB or high-speed PCB materials:

Df is between 0.01～0.005. The suitable upper limit of circuit board is 10Gb/S digital circuit;

Df is between 0.005～0.003. The suitable upper limit of circuit board is 25Gb/S digital circuit;

The circuit board with Df not exceeding 0.0015 is suitable for 50Gb/S or even higher-speed digital circuits.

Among the above factors, the operating speed of high-speed digital circuits is the main factor to consider when selecting high-frequency PCB or high-speed PCB materials. The higher the circuit speed, the smaller the Df value of the selected PCB. Circuit board materials with medium and low loss will be suitable for 10Gb/s digital circuits; PCB materials with lower loss are suitable for 25Gb/s digital circuits; PCB materials with ultra-low loss will be suitable for faster high-speed digital circuits, and its rate It can be 50Gb/s or higher.