pcb - Is it good to ground the polygon plane on the routing layer?

For my final project I have to measure multiple signals up to 10MHz with a TMS320F2809 processor which is clocked at 100MHz.

I have the following layer stackup:

• Top Signal


• Ground


• Signal


• Signal


• Source


• Bottom Signal

On the signal layers do I have to put a polygon plane? Is it a good idea to connect to the ground? Will it act as a capacitor between the trace and the ground polygon?

According the following description on the top and bottom layer should be routed only low frequency. Which range is low frequency)(1Hz up to ?)? I tried to follow that description, but when two IC was within 1cm range I routed on the layer where the ICs are.

Answer

It is not necessary to put polygon pours on your signal layers. However, there are a few advantages to adding ground pours.

1. 
   

   Ground pours on layers adjacent to the power plane will help with power plane decoupling for high frequency signals >500MHz. Henry Ott does a good job of explaining this. http://www.hottconsultants.com/techtips/decoupling.html

   
   


2. 
   

   Ground pours can be used as part of an impedance controlled transmission line called a Coplanar Waveguide.

   
   
   


3. 
   

   Adding polygon pours can help balance the copper distribution on multilayer boards and will prevent bowing and twisting of the PCB during manufacturing. here is a link to some good information about this http://www.multi-circuit-boards.eu/en/pcb-design-aid/copper-balance.html

   
   


4. 
   

   Polygon pours on outer layers can be used for thermal dissipation.