Doubts about 4 layer board

best 4 layer board

Hello friends,
I have made single & double layer boards.But since we are working in RF & Wireless applications I want to make multilayer board for reduced EMI/EMC.
I have following doubts about 4 layer board:--
1) I got to know that for reduced EMI/EMC best option is first layer--GND
second layer-- VCC
third layer--SIGNAL
fourth layer--GND.
But then from top & bottom layer there will be only gnd fill area.Since I heard about BLIND & BURIED VIA, can I place any other tracks on top & bottom layer?
2) Is it like for 4 layer board using PROTEL:
First layer: TOP LAYER--GND
second layer:MID 1 LAYER--VCC
third layer: MID 14 LAYER--SIGNAL
fourth layer:BOTTOM LAYER-- GND
3) What is internal power planes as mentioned in PROTEL--OPTIONS--LAYERS?
4) PLZ help me by tips & suggestions to make 4 layer board.

Thanks in advance,

chirag.

4 layer board

Ad1.
You can place tracks on Top and Bottom side but it will create voids in your GND areas (can even defragment it). Of course you have to place a small track and a via to escape from the component pin to internal layer.

Ad2.
The thing what really matters is how you instruct the PCB house to build your board, you can reorder layers if you wish.

Ad3.
If your internal layer is solid without tracks (like your VCC layer) you have an option to use power plane (negative artwork) or signal layer with copper area with voids around vias (positive artwork)

good luck!

hi
i designed a 4 layer board as following and didn't find any EMC probs.
toplayer-signal
innerlayer-gnd
innerlayer-vcc
bottomlayer-signal
i would like to know in what way this will have EMC effects when compared to the structure proposed by you.
will EMC effect be depending on order of layers?

ur suggestion would be appreciated.
cheers
skr

Hi skr,
I am not saying that by using stack-up proposed by u there will be EMC problems. That is standard stack up for 4 layer board.
But for multilayer boards following points are also important:--
1) Signal layers should be adjacent to a plane.
2) Signal layers should be tightly coupled to their adjacent layers.
3) Power & GND planes should be closely coupled together.
4) HIGH SPEED SIGNALS SHOULD BE BURIED LAYERS LOCATED BETWEEN PLANES.THUS PLANE ACTS AS SHIELD & CONTAIN RADITAION FROM HIGH SPEED SIGNALS.
5) Multiple GND planes are always useful.

By considering all these points the stack-up which I HAD MENTION IS BEST POSSIBLE.
I have collected this study material for preparation of 4 layer board.
Since u have worked on 4 layer board I think u can help me..
bye,
chirag