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.

Figure 2.

Screen printing with conductive ink is the newest form of FPC (called membrane) being produced today. In this application, carbon/silver (C/Ag) paste replaces the traditional copper conductor.

Figure 3.

The Coverlay dialog contains the following sections:

• Layers Definition: Define target layer for checking.
  • Coverlay Top Layer: Select the top Coverlay layer from layer list.
  • Coverlay Bottom Layer: Select the bottom Coverlay layer from layer list.
  • Silver Paste Top Layer: Select the top silver paste layer from layer list.
  • Silver Paste Bottom Layer: Select the bottom silver paste layer from layer list.
• Checking
  • Clearance between Coverlays: Check the clearance between Coverlay and Coverlay on the same layer.
  • Minimum Coverlay Size: Check Coverlay size. If the width or height of a Coverlay is smaller than given value, it is a fail.
    • Width: Set the width value for single a Coverlay.
    • Height: Set the height value for single a Coverlay.
  • Check Overlapping Width between Top and Bottom Coverlay: Check top and bottom Coverlays overlapping width.

    
    
    Figure 4.

  • Via Keepout within Coverlay which is overlapped with Silver Paste Area: Check that vias are placed in the Coverlay area.
  • Overlapping Width between Coverlay and Silver Paste: Set the overlapping width value between Coverlay and Silver Paste on the same layer. If measured overlapping width is smaller than a given value, it is a fail.
  • Check Overlapping Width between Top and Bottom Coverlays for given Axis: Check overlapping between the top and bottom Coverlay for given axis. If the measured overlapped width is smaller than the given width, it is a fail.
    • Width: Set the minimum overlapping width.
  • Clearance: Check the clearance for the Component and figure coverlay.
    • Component Coverlay: Check the clearance for the component coverlay.
      • All Component: Set All Component Coverlays as Target.
      • Component Group: Select the target component coverlay group from the component group list.
      • Clearance to Pattern: Clearance between the component coverlay and pattern.
      • Clearance to Via: Clearance between the component coverlay and via.
      • Clearance to Copper: Clearance between the component coverlay and copper.
    • Figure Coverlay: Check the clearance for the figure coverlay.
      • Clearance to Pattern: Clearance between the figure coverlay and pattern.
      • Clearance to Via: Clearance between the figure coverlay and via.
      • Clearance to Copper: Clearance between the figure coverlay and copper.
    • Exclude checking specific Nets: The specific net is excluded from the checking.