Design Rules Check (DRC) setup in PCB Design - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to set the minimum clearance rule in the DRC setup.

PCB Design

drc.set_minimum_clearance([1])

Drag options to blanks, or click blank then click option'

A0.35

B0.45

C0.25

D0.15

Attempts:

3 left

💡 Hint

Common Mistakes

Using a clearance value that is too small causing potential shorts.

Using a clearance value that is too large reducing PCB density.

The minimum clearance is commonly set to 0.25 mm to ensure safe spacing between traces.

2fill in blank

medium

Complete the code to enable the DRC rule for minimum trace width.

PCB Design

drc.enable_rule('[1]')

Drag options to blanks, or click blank then click option'

Amax_trace_width

Bmin_trace_width

Cmax_clearance

Dmin_via_diameter

Attempts:

3 left

💡 Hint

Common Mistakes

Enabling the wrong rule such as max_trace_width which is not a DRC check.

Using a rule name that does not exist in the DRC setup.

Enabling the 'min_trace_width' rule ensures traces do not go below the minimum width set.

3fill in blank

hard

Fix the error in the code to set the via drill size in the DRC.

PCB Design

drc.set_via_drill_size([1])

Drag options to blanks, or click blank then click option'

A0.6mm

B'0.6mm'

C"0.6"

D0.6

Attempts:

3 left

💡 Hint

Common Mistakes

Including units like 'mm' inside the parameter.

Passing the size as a string instead of a number.

The drill size should be a numeric value without units for the function to accept it correctly.

4fill in blank

hard

Fill both blanks to set the minimum annular ring and enable its DRC rule.

PCB Design

drc.set_min_annular_ring([1])
drc.enable_rule('[2]')

Drag options to blanks, or click blank then click option'

A0.15

Bmin_annular_ring

Cmin_via_drill

D0.25

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing annular ring with drill size.

Enabling the wrong rule name.

Setting the minimum annular ring to 0.15 mm and enabling the 'min_annular_ring' rule ensures proper via pad size.

5fill in blank

hard

Fill all three blanks to set the minimum solder mask clearance, enable its rule, and set the clearance value.

PCB Design

drc.enable_rule('[1]')
drc.set_solder_mask_clearance([2])
drc.set_rule_clearance('[3]', [2])

Drag options to blanks, or click blank then click option'

Amin_solder_mask_clearance

B0.1

Dmin_trace_clearance

Attempts:

3 left

💡 Hint

Common Mistakes

Using different rule names inconsistently.

Setting clearance values too large or too small.

Enabling the 'min_solder_mask_clearance' rule, setting the clearance to 0.1 mm, and applying it to the same rule ensures solder mask spacing is checked.

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