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Connecting to GND and VCC planes while routing

AKSHAYA

Hi

    I have created a board with four layers. The inner layers are ground and VCC and the VCC and GND nets of the circuit made electrically connected to these planes by changing the net name. How we can connect the top and botton VCC and GND tracks to these planes. Is it possible using via, burried via or blind via. Whether we can put vias where ever connections are required or we have to connect using only one two vias. If vis is to be used what should be  the specifications of thermal pad and anti pad?. I am using only SMD pads.

Hope somebody may be able to help me 

  • Hi

    Thanks for ur reply. The documents U have mentioned were very useful and I have gone through it.

    I have used a vias to connect between layers. The via specifications are thermal pad and anti pad "null"(because no through hole components)   The   shape parameters as DRC values. But when I am viewing only the power plane and vias  the whole layer  sees with hashed. No seperation is seen between the vias and the shapes. I think there should be  isolation around the vias of non power nets and no isolation of vias of power nets from the power plane. But it dosn't show any DRC error. What could be the problem? Hope U may help me.

    Regards
    Akshaya
  • Venkata,

    You wrote

    vramanan said:

    Here is a quick rule of thumb

    p.s. FHS means Finish Hole Size

    If the design requires a 0.012” +/- 0.003” finished plated through hole.

    Pad diameter = (0.012” + 0.005”) + 2x (0.001”) + 0.010”

    Anti-Pad Diameter= Pad Diameter+10

    Thermal Pad 

    I.D = Inner Diameter = Drilled hole size(FHS)+ 2 x(annular ring)+0.010”

    O.D=Outer Diameter = I.D + 0.020”

    Spoke width can be from min 8 mils

     

    but for vias less than 14 mil FHS use direct contact, that means zero thermal

    I'm very interested in the meaning of the various parameters and where they came from, especially for the ' (0.012” + 0.005”) + 2x (0.001”) + 0.010” '. I get that the 12 mils is the FHS. I think the 2x 1 mil is the plating thickness, leading to a bigger drill of say 14 mils. But what are the 5 and 10 mils in this equation?

    Similar question for the thermal pad, although I'm far less confirmed with that.

    Thanks!
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