Design Rules Check (DRC) setup in PCB Design - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding the Purpose of DRC Setup

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

A To generate the bill of materials for the PCB

B To automatically route all PCB traces without errors

C To verify that the PCB layout meets manufacturing and electrical constraints

D To simulate the electrical performance of the PCB

💡 Hint

Think about what ensures the PCB can be manufactured correctly and works as intended.

DRC setup is used to check if the PCB layout follows the rules required for manufacturing and electrical functionality, preventing errors before production.

❓ dax_lod_result

intermediate

Calculating Violations Count in DRC Report

Given a DRC report table with columns RuleType and ViolationCount, which DAX measure correctly sums all violations?

A Total Violations = SUM(DRCReport[ViolationCount])

B Total Violations = COUNT(DRCReport[RuleType])

C Total Violations = AVERAGE(DRCReport[ViolationCount])

D Total Violations = DISTINCTCOUNT(DRCReport[ViolationCount])

💡 Hint

Think about how to add up all violation counts.

SUM adds all values in the ViolationCount column, giving the total number of violations.

❓ visualization

advanced

Best Visualization for DRC Violations by Rule Type

You have a dataset with DRC violations categorized by rule type and severity. Which visualization best helps identify the most frequent and severe violations?

A Pie chart showing percentage of violations by rule type

B Line chart showing violations over time

C Scatter plot of violation locations on PCB layout

D Stacked bar chart showing count of violations by rule type and severity

💡 Hint

Consider a chart that compares categories and subcategories clearly.

A stacked bar chart allows comparison of violation counts by rule type and severity in one view, making it easy to spot the most frequent and severe issues.

🔧 Formula Fix

advanced

Identify the Error in DAX Measure for DRC Violations

Review the following DAX measure intended to calculate total DRC violations filtered by severity 'High':
Total High Violations = CALCULATE(SUM(DRCReport[ViolationCount]), DRCReport[Severity] = "High")
What is the error?

A The measure is correct and will work as intended

B The filter condition should use FILTER function for row context

C Severity column name is incorrect

D SUM cannot be used with CALCULATE

💡 Hint

Confirm if the direct filter in CALCULATE is valid DAX syntax.

The DAX measure is correct. CALCULATE accepts boolean filter expressions like DRCReport[Severity] = "High" directly, which modifies the filter context appropriately.

🎯 Scenario

expert

Optimizing DRC Setup for Complex PCB Designs

You are setting up DRC for a complex multilayer PCB with tight spacing and multiple signal types. Which approach best balances thorough error checking and reasonable run time?

A Run DRC only on the top and bottom layers to save time

B Use rule sets with different strictness for critical and non-critical layers and run incremental DRC during design

C Disable spacing rules to speed up DRC and run full check only before manufacturing

D Set all rules to the strictest values and run full DRC after every design change

💡 Hint

Consider how to keep checks effective but not slow down design work too much.

Using different rule strictness for critical layers and incremental checks balances accuracy and performance, avoiding unnecessary delays.

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