8layer PCB design

[jayasree jayaraj]

Hi,
I am trying to design a 8layer board using cadence Allegro. As I did only 2layer design I don't have much idea about more layers.can you please provide any tutorial or guidelines for 8layer designing.

 

[barry]

It’s 4 times as many layers. What’s your question? some of your layers should be ground and power planes, but it’s up you; there’s no rules about what your 8 layers should be.

 

[KlausST]

Hi,

I am trying to design a 8layer board

When I design: I design an application. And the application requirement tells how much layers I need to use. And for what "signals" these layers are used for.

It seems you doing it the other way round. You design an 8 layer board. Try to find which signals you want to route in the according layers.. then you look for an application which fits this requirement. Interesting....

****
I agree with Barry, there are no rules. But there are many discussions here in the forum and in the internet.

But most of them start with:
"I´m designing a HF board with ... requirements.."
"I´m designing a high densitiy FPGA board with ... interfaces... I/Os, devices..."
"I´m designing a high power inverter....."
"I´m designing a high precision multi channel data acquisition board.....with 16 bit precision and 10MHz bandwidth..."

Then it additionally depends whether / how much you want an autorouter to route the signals in the accrding layers.

Klaus

 

[jayasree jayaraj]

hi,
I have FPGA in my design..so how to add signal layers and how to route in those areas?

 

[barry]

hi,
I have FPGA in my design..so how to add signal layers and how to route in those areas?

I think your problem is learning how to use the tool. I don't know Allegro, but I'm pretty confident there's some information on how to add layers to a design, and how to select what layer you're routing on. These are fundamental operations.