MLB PCB design problem

[Detronic]

I got one multi-layer board i.e. 4-layer pcb board. I would like to do reverse engineering. But, there is one question, can i interchange the inner layers? That is, change inner layer 2 to inner layer 3 and inner layer 3 to inner layer 2.
What is the problem will happen to my board? For what i know is, inner layer are normally for power and ground plane, nornally. If i interchange it then accually the physical connections are still there. There suppose are no problem to the board. Why some design need the stack up structure in sequence? what i can not interchange them?

Stack Up Structure for 4-Layer board:
top signal ========
inner 2 ++++++++
inner 3 ########
bottom signal --------------

 

[Juglenaut]

Most likely not, a design is a design and may not be interchanged.

This all depends on the VIA's sometimes they go all the way sometimes not, and sometimes a VIA goes from one component to the next. VIA use positives, negatives, interchanges, interchanges from substrates. This all depends on how complex the sub layer is and sometimes it can be just as complex as the surface traces.

You would have to re-engineer the whole PCB.

 

[Russlk]

So you have a physical board and you want to swap the VCC and GND planes? That won't work. If you are doing a new layout you can specify which is which, but why do you care? Both VCC and GND are ground planes and provide the same shielding.

 

[Detronic]

Why GND must put at second layer, why not third layer? Is that is provide good compensation to noise? Some of the PCB board filled with copper GND, even double side.
I did some research on Speech Synthesis ICs and it application note give some tips of pcb designing(as attached). Does this application same with the MLB inner layer design?

 

[Russlk]

I am not an expert on PC layout, but I see no reason to put GND on any particular layer. It is common practice to put VCC and GND on inner layers, and to run signals on a 5th layer between them for shielding.

 

[fredsm]

The GND and Vcc layers are essentially the same (or SHOULD
be) for bypass and shielding considerations, with lots of caveats.
If strip-line impedance is important, it is easier to design and
control with odd layers (i.e., a virtual or real GND between
signal layers), although most boards I have seen use the
middle layer as signal, with large ground planes placed as
necessary for isolation/shielding/separation. On an even-
layered board, it would make more sense to make GND/Vcc
layers 1-3 or 2-4, depending on the enclosure.
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