Design Rules Check (DRC) setup in PCB Design - Real Business Scenario

Scenario Mode

👤 Your Role: You are a PCB design engineer working on a new circuit board layout.

📋 Request: Your manager wants you to set up Design Rules Check (DRC) parameters to ensure the PCB layout meets manufacturing and electrical standards before production.

📊 Data: You have a dataset of PCB layout parameters including trace widths, spacing, via sizes, and layer stack information.

🎯 Deliverable: Create a report and dashboard showing the configured DRC rules, their thresholds, and a summary of any violations found in the sample PCB layout data.

Sample Data

Rule Name	Parameter	Minimum Value (mil)	Maximum Value (mil)	Current Layout Value (mil)	Violation
Trace Width	Width	6	50	5	Yes
Trace Spacing	Spacing	6	---	7	No
Via Diameter	Diameter	10	---	12	No
Annular Ring	Ring Width	5	---	4	Yes
Component Clearance	Clearance	10	---	15	No
Silkscreen Over Pad	Overlap	0	0	1	Yes
Board Edge Clearance	Clearance	15	---	20	No
Power Trace Width	Width	20	---	18	Yes

1

Step 1: Organize the DRC rules data into a table with columns: Rule Name, Parameter, Min Value, Max Value, Current Layout Value, Violation.

Use the provided sample data table as the base dataset.

Expected Result

A clear table showing each DRC rule with its limits and current layout values, highlighting violations.

2

Step 2: Create calculated measures to count total rules and total violations.

Total Rules = COUNTROWS('DRC Rules') Total Violations = COUNTROWS(FILTER('DRC Rules', 'DRC Rules'[Violation] = "Yes"))

Expected Result

Total Rules = 8 Total Violations = 4

3

Step 3: Create a measure to calculate the percentage of rules violated.

Violation Percentage = DIVIDE([Total Violations], [Total Rules], 0) * 100

Expected Result

Violation Percentage = 50%

4

Step 4: Build a dashboard visualization with: - A card showing Total Rules - A card showing Total Violations - A card showing Violation Percentage - A table listing all rules with their parameters, current values, and violation status

Configure visuals in your BI tool accordingly.

Expected Result

Dashboard clearly shows 8 total rules, 4 violations, 50% violation rate, and detailed rule status.

5

Step 5: Interpret the dashboard to identify critical DRC issues needing correction before PCB manufacturing.

Review the rules with 'Yes' in Violation column and prioritize fixes.

Expected Result

Critical issues found in Trace Width, Annular Ring, Silkscreen Over Pad, and Power Trace Width.

Final Result

-----------------------------
| DRC Setup Dashboard       |
|---------------------------|
| Total Rules:       8      |
| Total Violations:  4      |
| Violation %:     50%      |
|---------------------------|
| Rule Name       | Violation|
|-----------------|----------|
| Trace Width     | Yes      |
| Trace Spacing   | No       |
| Via Diameter    | No       |
| Annular Ring    | Yes      |
| Component Clearance | No    |
| Silkscreen Over Pad | Yes   |
| Board Edge Clearance | No   |
| Power Trace Width | Yes    |
-----------------------------

✓Half of the DRC rules are violated in the current PCB layout.

✓Trace Width and Power Trace Width are below minimum required sizes, risking electrical issues.

✓Annular Ring and Silkscreen Over Pad violations could cause manufacturing defects.

✓Immediate attention is needed to fix these violations before production.

Bonus Challenge

Extend the dashboard to include trend analysis of DRC violations over multiple PCB revisions.

Show Hint

Add a date or revision column to your data and create line charts showing violation counts over time.

Practice

1. What is the main purpose of setting up Design Rules Check (DRC) in PCB design?

easy

A. To ensure the PCB layout meets manufacturing and electrical requirements

B. To create the schematic diagram of the circuit

C. To program the microcontroller on the PCB

D. To generate the bill of materials automatically

Solution

1. Step 1: Understand DRC role in PCB design

   DRC is used to check if the PCB layout follows specific rules for spacing, sizes, and electrical constraints.

2. Step 2: Identify the main goal of DRC setup

   The goal is to catch errors early to ensure the PCB can be manufactured and works correctly.

3. Final Answer:

   To ensure the PCB layout meets manufacturing and electrical requirements -> Option A

4. Quick Check:

   DRC purpose = ensure design rules met [OK]

Hint: DRC checks design rules before manufacturing [OK]

Common Mistakes:

• Confusing DRC with schematic creation
• Thinking DRC programs components
• Assuming DRC generates parts list

2. Which of the following is the correct way to set a minimum clearance rule in a DRC setup?

easy

A. Clearance == 0.15mm

B. Clearance >= 0.15mm

C. Clearance < 0.15mm

D. Clearance = 0.15mm

Solution

1. Step 1: Understand clearance rule syntax

   In DRC setup, you define the minimum clearance as a fixed value, e.g., Clearance = 0.15mm.

2. Step 2: Identify correct syntax for minimum clearance

   Using an equality assignment sets the rule; inequalities are not used in this context.

3. Final Answer:

   Clearance = 0.15mm -> Option D

4. Quick Check:

   Minimum clearance set by assignment = value [OK]

Hint: Use assignment (=) to set DRC clearance values [OK]

Common Mistakes:

• Using inequality signs instead of assignment
• Confusing comparison operators with rule definitions
• Writing clearance as a condition instead of a value

3. Given the following DRC rules:
MinTrackWidth = 0.2mm
MinClearance = 0.15mm
If a track is 0.18mm wide and the clearance between two tracks is 0.14mm, what will the DRC report?

medium

A. Errors: Track width and clearance below minimum

B. Error: Track width below minimum

C. Error: Clearance below minimum

D. No errors, all rules met

Solution

1. Step 1: Check track width against minimum

   The track width is 0.18mm, which is less than the minimum 0.2mm, so this violates the rule.

2. Step 2: Check clearance against minimum

   The clearance is 0.14mm, less than the minimum 0.15mm, so this also violates the rule.

3. Final Answer:

   Errors: Track width and clearance below minimum -> Option A

4. Quick Check:

   Width < 0.2mm and Clearance < 0.15mm = Errors [OK]

Hint: Compare values directly to minimum rules [OK]

Common Mistakes:

• Ignoring one of the two rule violations
• Assuming no error if only one rule fails
• Mixing up width and clearance values

4. You set a DRC rule for minimum hole size as MinHoleSize = 0.3mm. After running DRC, you still see errors for holes sized 0.35mm. What is the most likely cause?

medium

A. The holes are actually smaller than 0.3mm

B. The hole size units are mismatched (e.g., inches vs mm)

C. The DRC rule syntax is incorrect

D. The DRC tool does not check hole sizes

Solution

1. Step 1: Verify units used in hole size and DRC rule

   If the holes are 0.35mm but errors appear, units might be mismatched, e.g., holes measured in inches but rule in mm.

2. Step 2: Confirm DRC rule syntax and tool capability

   The syntax MinHoleSize = 0.3mm is correct and DRC tools do check hole sizes, so these are unlikely causes.

3. Final Answer:

   The hole size units are mismatched (e.g., inches vs mm) -> Option B

4. Quick Check:

   Unit mismatch causes false errors [OK]

Hint: Always check units match between design and rules [OK]

Common Mistakes:

• Assuming syntax error without checking units
• Ignoring unit differences between design and rules
• Thinking DRC ignores hole sizes

5. You want to set up a DRC rule that enforces a minimum spacing of 0.2mm between copper traces but allows a smaller spacing of 0.1mm between traces on different layers. How should you configure the DRC rules?

hard

A. Set MinClearance = 0.1mm for all layers without exceptions

B. Set MinClearance = 0.2mm and ignore layer differences

C. Set MinClearance = 0.2mm and enable LayerSpecificClearance = true with InterLayerClearance = 0.1mm

D. Set MinClearance = 0.3mm to cover all cases

Solution

1. Step 1: Understand clearance rules for same and different layers

   Minimum spacing between traces on the same layer is 0.2mm, but between layers it can be smaller (0.1mm).

2. Step 2: Configure DRC to handle layer-specific clearances

   Enable a setting like LayerSpecificClearance = true and set InterLayerClearance = 0.1mm to allow smaller spacing between layers.

3. Final Answer:

   Set MinClearance = 0.2mm and enable LayerSpecificClearance = true with InterLayerClearance = 0.1mm -> Option C

4. Quick Check:

   Layer-specific clearance rules = Set MinClearance = 0.2mm and enable LayerSpecificClearance = true with InterLayerClearance = 0.1mm [OK]

Hint: Use layer-specific clearance settings for different spacing [OK]

Common Mistakes:

• Applying one clearance value for all layers
• Ignoring inter-layer spacing rules
• Setting clearance too large and restricting design