How to describe the selection of boards for PCB proofing

Material requirements for PCB

In today's wireless communication equipment, the RF part often adopts a miniaturized outdoor unit structure, while the RF part, the IF part of the outdoor unit, and the low-frequency circuit part that monitors the outdoor unit are often deployed on the same PCB board material. Therefore, there is a high requirement for PCB materials on how to prevent interference between RF, IF and LF circuits

PCB proofing

Hybrid circuit is a big problem, it is difficult to have a perfect solution. In general, RF circuits are laid out as an independent board in the system, and even have a special shielding chamber. In addition, the RF circuit is generally a single or double sided board, and the circuit is relatively simple. All these are to reduce the impact on the distribution parameters of the RF circuit and improve the consistency of the RF system. Compared with general materials, RF circuit boards tend to use high Q value substrates, which have small dielectric constant, small distributed capacitance of PCB transmission lines, high impedance and small signal transmission delay.

In the mixed circuit board design, although RF and digital circuits are built on the same PCB, they are generally divided into RF circuit area and digital circuit area for layout and wiring. The grounding through hole tape and shielding box are used for shielding.

In high-speed and high-density PCB design, crosstalk really needs special attention, because it has a great impact on timing and signal integrity. The following points should be noted:

Select the appropriate termination method. Continuity and matching of routing characteristic impedance control.

The size of the wire spacing. Generally, the spacing is twice the line width. Through simulation, we can know the influence of routing distance on timing and signal integrity, and find out the minimum tolerable distance. The results of different PCB chip signals may be different.

The materials for circuit board proofing generally include FR-4, high frequency materials (CCL), Rogers, HTG, MTG, NTG, HF and other plates

PCB proofing is generally based on the requirements of the customer's final product, that is, the formal order requires the use of any board for PCB proofing.

Therefore, there are all kinds of materials for the printed sample of the circuit board.