PCB Polygon Pour Suggestion

[sakibnaz]

Hi all.

I am using Altium Designer for PCB design. For my Design, I want to use Polygon Pour. I would like to have your advice regarding my below queries:

- For Polygon, whats the basic idea to use it? I mean ... how I can divide Polygon ... where I'll use VCC Plane and where GND Plane?
- If I use TOP Layer Plane for VCC and BOTTOM Layer for GND ... will it be a problem (due to any Capacitance generation issue)?
- Is 10mil Clearance good for PCB which contains supply of +12V (3AMPH), +5V (1.5AMPH) and +3.3V (500mAMPH)? Or better to create separate clearance or each Voltage Line?
- Generally we always use thick power Traces. Is is also better to use thick GND Traces or GND Traces can be thin?

Thanks.

Sakibnaz.

 

[goldsmith]

Hello Dear Sakibnaz
At first step , i want describe , the aim of polygon : It depends on you circuit parameters , for example : frequency of operation , voltage value , current value , sensitivity , Signal / noise Ratio / and some other things .

ok , for more information about , polygon , can you tell me about the frequency of operation of your circuit , please?
Best Wishes
Goldsmith

 

[sakibnaz]

Thanks very much for your prompt reply.

My design is ATMel AT91SAM7S64 MCU based which is using XTAL of 18.432MHz.

Sakibnaz.

 

[goldsmith]

Ok , at first , looking , it appears it supply voltage is simple DC . but it is not correct . because the frequency of current will be about 18.432MHZ . thus you should connect a capacitor from DC supply to the VCC pin of IC , nearby of that .
Ok lets come back to the polygon issue : at high frequencies it is better to use continuous polygon . but your frequency is not very high . so you can use a simple polygon , with windows ( at high frequencies , it should not has windows ) . and you'll need to connect your ground to the polygon .( the microcontrollers are sensible to noise ) thus you can protect your circuit from the area noise . if your area has many noise that produced by machines ( the places , for instance , factories ) , you can use two layer board , that it's second layer is just polygon , that connected to the ground , to be ensure that noises can't destroy the behaviour of your circuit.
Good luck
Goldsmith

 

[sakibnaz]

Dear Goldsmith.

Yes the design is 2-Layer.

- So, will I use GND Plane for both TOP and BOTTOM Layer?
- If I use VCC for TOP Layer Plane and GND for BOTTOM Layer Plane .... then will it be a problem?

Sakibnaz.

 

[goldsmith]

Yes . and as i know you should not use vcc as polygon , because the noises can permeable on that .

 

[marce]

Two layer digital, copper pour GND top and bottom and add loads of stiching vias. Run power with thick traces.