Quick Tutorial: Real-Time Design for Fabrication (DFF)

June 19, 2019 Team EMA


 

By setting Design for Fabrication (DFF) constraints, you can catch issues in your design before you manufacture and avoid delays or even costly design respins. OrCAD PCB Designer Professional uses visual indicators to flag these issues in real-time as you design, saving you time by correcting the design as you go instead of after completion. This tutorial will show you how to use and configure the Design for Fabrication constraints included in OrCAD PCB Designer Professional, to ensure your board can be efficiently manufactured. If you would like to follow along with this tutorial, you can download the design files here.
 

Step 1: Open your design in OrCAD PCB Designer Professional and open the Constraint Manager by selecting Setup→ Constraints from the menu.
 

Select the Manufacturing Tab in the Worksheet Selector section of the Constraint Manager.
 

Expand the “Design for Fabrication” (DFF) tab to view the available constraints.
 

Note: Constraint rules can be created in the “DFF Constraint Set” section and assigned to portions of the board in the “Design” section. For information on all the available Design for Fabrication Constraints, see the final note in this blog post.
 


 

Step 2: Create a Constraint Set (CSet). Select the Annular Ring Worksheet under “DFF Constraint Set”.
 

Click “”.  Set the following information:

  • DFFAnnularRingCset: Mask_Rigid
  • CSet Usage: Non-Etch
     

Click OK.
 


 

Set the following values for the Mask_Rigid Constraint Set:
 

All Pins:

  • Missing Mask: ON
  • Pad to Mask: 0.025
     

All Vias:

  • Missing Mask: ON
  • Pad to Mask: 0.025
     


 

Step 3: Assign the Constraint Set. Select the Annular Ring Worksheet under “Design”.
 

Expand Flexi_Stiffener→ Mask. Assign the Mask_Rigid Constraint Set to SOLDERMASK_TOP and SOLDERMASK_BOTTOM.
 

Expand Primary→ Mask. Assign the Mask_Rigid Constraint Set to SOLDERMASK_TOP and SOLDERMASK_BOTTOM.
 


 

Close out of the Constraint Manager Window.
 

Step 4: Place Component “J6”. In the Options Tab, check the box next to “J6”.
 

Note: If this is not visible in your design, select Place→ Components Manually from the menu.
 

Place the component on the board under the Cadence logo by using “R” on the keyboard to rotate the component. Click to place.
 


 

Note: DRC Errors are automatically flagged in real-time.
 

Step 5: View the DRC Errors. Place the curser over the DRC Marker to view more information.
 


 

Step 6: Modify the Design Padstack. Right click on any of the pins in J6 and select Modify Design Padstack→ All instances.
 


 

Note: This will bring up the Padstack Editor. If you are having trouble selecting the padstack, in the Find tab uncheck “DRC Errors” and “Symbols”.
 

Select the “Mask Layers” tab in the Padstack Editor.
 

Set the following values:
 

Soldermask Top

  • Geometry: Circle
  • Diameter: 1.3
     

Soldermask Bottom

  • Geometry: Circle
  • Diameter: 1.3
     


 

Step 7: Update the design. Select File→Update to Design and Exit.
 

The DRC Errors have been resolved and the DRC Markers are no longer visible.
 


 

Note: The following Design for Fabrication Constraints are available:
  • Outline: Checks spacing of design objects to the Board Outline and/or Cutouts. Values can be set for traces, pins, vias and other non-signal geometry.
  • Mask: Checks for minimum mask sliver width and square areas of mask islands where mask material may be too small for proper adherence to the substrate.
  • Annular Ring: Checks size requirements in the relationship of hole to pad and pad to mask for pins and vias.
  • Copper Features: Checks for minimum line width, antenna and acid traps.
  • Copper Spacing: Checks for the minimum manufacturing spacing allowed between trace, shape, pin pad, via pad, non-plated hole, and non-signal geometry objects.
  • Silkscreen: Checks the space from pin pads, via pads, and non-plated holes. Minimum character width and minimum line width values are also defined here.
     

By utilizing constraints for common fabrication issues based on your manufacturer’s specific requirements, you can detect and correct any potential issues DURING your design process. Minimize costly design respins and delays during the manufacturing process by ensuring the manufacturability of your designs with Real-Time Design for Fabrication in OrCAD PCB Designer Professional.

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