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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 

Parents

  •  Hi Akshaya

    my understanding is you have SMD components on either side of the board and want to connect the VCC/GND signals to the shapes on the inner layers

    I assume that you have created the shapes on the inner layers and assigned them to respective nets

    VCC layer should have a shape that is assigned to VCC and GND layer to GND net

     

    having achieved that, 

    you have to use vias to connect the top/bottom side SMD component's individual pins to their respective planes

     

    for example let's assume U1 pin 1 is connected to VCC and U1.10 is to GND

    you have to draw a cline from U1.1 and add a VIA in a clearance away from any obstruction

    The VIA will automatically connected to the respective plane

     This happens for the GND as well

    Now regarding the VIA sizes/Drill

    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

    regards

    Venkata

     

Reply

  •  Hi Akshaya

    my understanding is you have SMD components on either side of the board and want to connect the VCC/GND signals to the shapes on the inner layers

    I assume that you have created the shapes on the inner layers and assigned them to respective nets

    VCC layer should have a shape that is assigned to VCC and GND layer to GND net

     

    having achieved that, 

    you have to use vias to connect the top/bottom side SMD component's individual pins to their respective planes

     

    for example let's assume U1 pin 1 is connected to VCC and U1.10 is to GND

    you have to draw a cline from U1.1 and add a VIA in a clearance away from any obstruction

    The VIA will automatically connected to the respective plane

     This happens for the GND as well

    Now regarding the VIA sizes/Drill

    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

    regards

    Venkata

     

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