Some Questions Met When Designing PCBs

Usually,there are always some questions met when you designing your PCBs, today i will introduce some questions about designing rapid PCBs and what should focus on.

 

1.In rapid PCB Design, how to solve the problem of signal integrity?

Basically signal integrity is the impedance matching problem. Factors that influence of the impedance matching are the signal source structure and output impedance, the characteristic impedance line, characteristics of the load, line topology (topology) architecture etc.. The solution is the termination and adjust the routing topology.

 

2.In rapid PCB Design, the blank area of the signal layer can be applied to the copper, and how to allocate the deposited copper on the ground and the power?


In general, the majority of copper in the blank area is grounded, just at the high speed signal line next to deposited copper should pay attention to the distance between the copper and the signal line, because the deposited copper will reduce the characteristic impedance of the line.Also note that it does not affect the characteristic impedance of the layer, such as the structure of the dual strip line.

 

3.In rapid PCB Design,How to consider the impedance matching problem?


Impedance matching is one of the key elements of design, and the impedance value has a positive relationship with the route.For example, microstrip or stripline/double stripline.The distance between the reference layer (power layer or stratum), the line width, the material and so on will affect the characteristic impedance of the line,that is to determine the impedance value after wiring.The only way to solve the problem is to avoid the occurrence of impedance discontinuity.

 

4.What is FR-4 in PCB fabrication?

This is a fiber glass composite that is meant to make the PCB to be flame resistant or flame retardant (FR). There are other options other than FR-4 substrate laminate but they do not have as good strength to weight ratio as the FR-4. This has made FR-4 to become a well acceptable standard.

 

5.In 2G high frequency PCB design,Line, typesetting, what aspects should focus on?

2G or more high frequency PCB RF circuit design are not in the design of high-speed digital circuit.RF circuit layout and routing should be considered together with the schematic,because they will cause distribution effect. Moreover, the RF PCB design of some passive components is defined by parameterization, and special shaped copper foil.Therefore, it is required that the EDA tool can provide parameterized device, and can edit special shape copper foil.In general, RF PCB design requires a dedicated RF circuit analysis tool.