Explanation of layer stacks (guidelines and information)

[qasmi]

Layer stacks

Hello All,

Can anyone tell me about the layer stack. for a 12 layer board, what is the best layer stack.

what should be the thickness of the layers. how many planes are recommended and in what order?? and other recommendations and guidelines ... thank you

regards

 

[senilicus]

Re: Layer stacks

Hi,

There is no such thing as "the best layer stack". it all depends on your design requirements and your pcb fabricators material.

One major thing to do is to make sure that the stackup is symmetrical from the middle of the board. This will reduce bow and twist.

If possible put a ground and power plane together. This way they will form a capacitor.

The easiest way to start is to ask for a stackup at you'r pcb fabricator. They know wich materials are on stock.
With this default stackup you can do you'r impedance calculations. If you can not create the impedances you need, contact the pcb fabricator for other prepeg and core thickness possible.

When you'r stackup is finished contact you'r pcb fabricator again to let them review you'r stackup.

Good luck

 

[eswar_babu77]

Re: Layer stacks

when u r deciding the stackup, first analyse design requirements. As layer stackup can be built with different combinations. But as my friend said it should be symmetrical. When its a high speed design and impedence controlled design make sure u have reference plane for each and every siganl layers.

 

[muralicrl]

Re: Layer stacks

Hi,

Kindly refer the site

http://www.hottconsultants.com/techtips/pcb-stack-up-5.html

Regards,

N.Muralidhara

 

[sandhya.im]

Re: Layer stacks

Hi quasmi,

First of all identify the constraints of your board.

i.e,
what are the impedance matching requirements
what are the constraint interfaces used in your board

& calculate the layer thickness using any of the available stack up calculators.(There are many free calculaotrs on web).

Now create a general stack up and consult your manufacturer for these requirements.
They will suggest a good stack up as per their standards.

I am attaching a standard stack up for the 12 layer board.
Check for the attachments for a general awarenes of Layer stack-up.

Regards,
sandhya