Jim,



we have taken a survey among our suppliers and these are the results, which are

based on a 4 layer board.

They are not accurate because they differ about 10% from one manufacturer to the

other, but they can serve as a clue.



*2 layer                               50%

*4 layer                              100%

*4 layer (2 + 2 HDI)                  120%

*6 layer                              130%

*6 layer (4 + 2 HDI)                  150%

*8 layer                              160%

*6 layer (4 + 2 HDI + buried vias)    170%

*8 layer (6 + 2 HDI)                  180%

*8 layer (6 + 2 HDI + buried vias)    200%



As for your second question, I would use the Sig1, GND,VCC,Sig2 stackup. The

alternative requires HDI technology (vias in pad) and the planes are more

fractured.This may lead to possible radiation from the return currents which are

forced to flow around the openings in the plane. With the first stackup you can

still fill unused areas on both surfaces of the board with GND, if you connect

them with numerous vias to the inner layer plane.



Volkmar





Jim Mathis wrote:



> Assuming all other considerations being equal (size, # of holes, hole sizes,

> etc.), what is the typical cost adder for going 4-layer from 2-layer?  1.5X,

> 2X. etc?

>

> Also, in an EMI-sensitive environment, how would you recommend the layer

> stack-up?  Signal 1, Ground, Supply, Signal 2  OR Ground, S1, S2, Supply?  OR

> something else?

>

> Thanks.



--

  Volkmar Huß                                   Dräger ProTech GmbH

  Engineering Electronic Circuit Boards         Elektronikbaugruppen

  Phone +49 451 882-3998                        Moislinger Allee 53/55

  FAX                -4365

                                                23542 Lübeck / Germany

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