Coverlay Open Area

Check rules for Coverlay.

The Coverlay is the insulating layer placed over the exposed conductors. It is typically constructed of a pre-cut piece of polyimide film laminated over the conductors using either acrylic or epoxy adhesive. Coverlay is used to protect and insulate the exposed surface of the circuit.
Figure 1.


The Coverlay Open Area dialog contains the following sections:
  • Target Layer Definition: Define target layer for checking.
    • Layer Definition for Check Area: Select target layer from layer list.
    • Coverlay Layer Definition: Define Coverlay layer for checking.
      • Coverlay Data Type: Select Coverlay layer data type between Positive and Negative.
      • Top/Bottom: Select Coverlay top and bottom layer from layer list.
  • FPCB Layer Definition: If PCB is a mixed design, as in FPCB (Flexible PCB) and Rigid PCB together, it is able to check the clearance with a certain value for FPCB. In this case, you can define the FPCB layer for checking.
    • Layer Name or Layer Comment: Can define the FPCB layer information by layer name or comment of layer.
    • FPCB Layer Filter: Set the layer information.
      • Import(.txt): Apply Filter Type based on the characters entered in the .txt file.
        • Apply as a prefix when (|F|) ABC is entered in the .txt file.
        • Apply as a mid-string when ABC is entered in the .txt file.
        • Apply as a suffix when ABC(|P|) is entered in the .txt file.
      • Export(.txt): Export the characters registered in the String Item in .txt file format.
  • Checking: Check Coverlay opened for patterns and vias.
    Figure 2.


    • For coverlay opening, check Pattern existence: Check pattern Coverlay opening.
      • Exclude Checking for Coverlay Opened for Both Sides: If pattern Coverlay data are open in the top and bottom, PollEx DFM will not check for this pattern.
    • For coverlay opening, check Via existence: Check via Coverlay opening.
      • Exclude Checking for Nets: Exclude vias connected to certain nets. To do this, select nets from netlist.
    • In Case of Via on Pad, Check Coverlay on the Other Side of Component Placement: If a via is placed on pad, check the other side to see if there is a Coverlay or not. If there is no Coverlay on the other side, it is a fail.
      Figure 3.


      • Except for Selected Via Hole Size: For certain size of via holes, exclude checking for them.
    • Checking if the coverlay open area is rectangle shape: Check whether the coverlay open area is designed in a square shape in order to prevent the coverlay film from tearing.
      Figure 4.