What Is DRC ?

Introduction: What Is DRC ?

Design Rule Checking (DRC) is a process used to identify errors and mismatches such as spacing & trace widths in a PCB design/layout. The layout of a PCB board is designed using software, each PCB fabricator has a set of rules which they publish that specify various parameters such as what the spacing between each line should be, the minimum size of vias, the width of a line etc.

Once a design is submitted to a PCB Fabricator, they run a DRC to ensure that the submitted design complies to their published standard. This ensures that the PCB will be fabricated to spec. If there are any mis-matches the DRC points them out and the designer then updates the design/layout accordingly. DRC (Design Rule Checking) is a must to ensure there are no design violations in the PCB. This check is done prior to the manufacturing of the final board.
The Design Rules are different for each PCB fabricator. Users should check the design rules of a PCB fabricator before submitting a PCB Design to the manufacturer.

Step 1: Design Rule Setting

Via at: Tools > Design Rule…, or Via: right-click the canvas - Design Rule… to open the Design Rule setting dialog.

The unit follow the canvas unit.
Rule: The default rule named “Default”, you can add the new rule you can rename and set parameters for it. Each net can be set a rule.

Track Width: Current rule’s track width. The PCB track width can not less than this value.

Clearance: The clearance of different objects which have different net. The clearance of the PCB can not less than this value.

Via Diameter: The via diameter of current rule. The via diameter of the PCB can not less than this value. Such as the Hole/Multi-layer Pad’s diameter.

Via Drill Diameter: The via drill diameter of current rule. The via drill diameter of the PCB can not less than this value.

Track Length: All track length of current rule. The length of tracks belong to a same net should not be longer than this value.Including the arc lenghth. When the input box is empty the length will be unlimited.

Realtime DRC: After enable, when you routing the DRC will checking all the time, when appear the error the canvas will show the “X” marking.

Check Object to Copper Area: Check the clearance of the objects to copper area. If you disable this option, you must rebuild the copper area before generating the Gerber with SHIFT+B.


Check Object to Board Outline: When you enable, you can set a value to check the clearance of the objects to board outline.

Apply Design Rule while Routing and Placing Via: When you routing and placing a new via, them will follow the design rule to set them width and size.

Show DRC Boundary while Routing: When routing you will see a oultine around the track. Its diameter depends on desgin rule.

Step 2: Set Rule for a Net

  1. Click the “new” button to create a rule, or use the default rule
  2. Select one or more networks on the right, support holding down the CTRL key for multiple selection, and also can perform keyword filtering and rule classification filtering
  3. Then select the rule you want to set in the “set rules” section below and click the “apply” button. The network applies the rule.
  4. Click the “Settings” button to apply the rule.

Step 3: Check the DRC Error

Via “Design Manager - DRC Error“ or “Top Menu - Design - Check DRC“, click the refresh icon to run the DRC. If your PCB is a big file, and have the copper area that will take some times to check the DRC, please wait a while.

After checking, you can view all the error at the “DRC Error”, click the error the related objects will be highlighted.

Step 4: DRC Error Type

Clearance: Object to Object. If two different net objects too close, and the distance less than the Design Rule clearance, it will show the Clrearance error.

Step 5: Track Length: the Track Length of the All Same Net Tracks Must Less Than Design Rule Track Length.

Step 6: Track Width: the Track Width Must Must Large Than Design Rule Track Width.

Step 7: Via Diameter: the Via Diameter Must Large Than Design Rule Diameter.

Step 8: Via Drill Diameter: the Via Drill Diameter Must Large Than Design Rule Drill Diameter.

Step 9:

Note:

  • When you convert a schematic to PCB, the real time DRC is enable. But in the old PCB, the real time DRC is disable. you can enable it in the image as above.
  • Design rule checking can only help you find some obvious errors.
  • The color of the DRC error can be set in the layer manager

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