Component Shield

This DFE rule checks for the component ground shielding status.

To solve EMI problems, the designer uses shielding signal traces or ground vias. To solve component EMI problems, the designer can shield a component with mechanical structures. This method stabilizes the component and protects other signal effects.
  • Item: Enter item name.
  • Check Type: Select required test.
    • Component Shield: Check if component is fully surrounded with ground plane, horizontally or vertically.
    • Fill-Cut: Check if fill-cut exists under the IC.

      Figure 1.
    • Inductance Fill Cut: Check if fill-cut exists under the IC. If some signals exist under the IC, the ground plane should exist between signal layer and IC placement layer.

      Figure 2.
    • Copper Fill: Check if copper-fill exists under the IC. (Top/Bot Layer)

      Figure 3.
  • Comp: Select a component group that needs shielding.
  • GND Net: Select a ground net group.
  • Measure Base: Define a distance measuring object type – COC (Component Overlap Checking Area), Pad or Silk + Pad.
  • Distance: Assign a distance from a ground to the measuring object defined in ⑤.
  • Check Point Count: If you want to check the shield by checking many points around the component, define the number of checking points in the component. (4/8/12/16/20/24) If one of the check points does not overlap with ground, it reports as failed.

    Figure 4.
  • Vertical Check: Check vertical shielding. (Ex: Top component: check TOP and Layer1)
  • Min Ratio: Define the required minimum shield ratio. If you enable this option, the check point count value⑦ will be ignored.
    • Horizontal shield ratio = shield length/sum of check area boundary length
    • Vertical shield ratio = shield area/check area

      Figure 5.
  • Min Thermal Via Count: Check the minimum thermal via count under the component. This option is valid only when you select Component Fill as a check type option.
A component that is very sensitive against EMI may affect noise to other patterns or components. To prevent this, it is better to use ground shielding for the component. Perfect shielding is impossible. It is reasonably good if the shielding is over 80 percent.

Figure 6.