Common PCB design mistakes - Dashboard Guide

Dashboard Mode - Common PCB design mistakes

Goal

Understand the most frequent mistakes in PCB design and their impact on production and performance.

Sample Data: Common PCB Design Mistakes

Mistake	Frequency (%)	Impact Level	Cost Impact ($)	Detection Stage
Incorrect trace width	25	High	1500	Manufacturing
Insufficient clearance	20	High	1800	Testing
Wrong component placement	15	Medium	900	Assembly
Missing vias	10	Medium	700	Manufacturing
Improper grounding	12	High	1600	Testing
Silkscreen errors	8	Low	300	Assembly
Thermal issues	10	High	1400	Testing

Dashboard Components

• KPI Card: Total Cost Impact
  Formula: SUM of Cost Impact ($) = 1500+1800+900+700+1600+300+1400 = 8200
• Bar Chart: Frequency of Mistakes (%)
  Shows each mistake's frequency as bars for easy comparison.
• Pie Chart: Impact Level Distribution
  Shows percentage of mistakes by impact level (High, Medium, Low).
• Table: Detailed Mistakes Data
  Shows all columns from sample data for reference.

Dashboard Layout

+----------------------+---------------------+
|      KPI Card        |    Bar Chart        |
|  Total Cost Impact   | Frequency of Mistakes|
+----------------------+---------------------+
|        Pie Chart                      |
|    Impact Level Distribution         |
+-------------------------------------+
|           Detailed Mistakes Table    |
+-------------------------------------+

Interactivity

Filter by Detection Stage (Manufacturing, Testing, Assembly):

• Updates Bar Chart to show frequencies only for selected stage.
• Updates Pie Chart to reflect impact levels for filtered data.
• Updates Table to show only rows matching the selected stage.
• KPI Card updates total cost impact for filtered mistakes.

Self Check

If you add a filter for Detection Stage = Testing, which components update and what changes occur?

• KPI Card: Total Cost Impact updates to 1800 + 1600 + 1400 = 4800
• Bar Chart: Shows frequencies for Insufficient clearance (20%), Improper grounding (12%), Thermal issues (10%) only.
• Pie Chart: Reflects impact levels for these three mistakes (High impact mostly).
• Table: Displays only rows where Detection Stage is Testing.

Key Result

Dashboard shows common PCB design mistakes with their frequency, impact, cost, and detection stage, enabling focused quality improvements.

Practice

1. Which of the following is a common mistake in PCB design related to component placement?

easy

A. Placing components too close causing soldering issues

B. Using correct footprint sizes for components

C. Ensuring clear labeling of components

D. Following manufacturer recommended spacing

Solution

1. Step 1: Understand component placement importance

   Components placed too close can cause solder bridges and assembly problems.

2. Step 2: Identify the mistake

   Placing components too close is a common error that leads to manufacturing defects.

3. Final Answer:

   Placing components too close causing soldering issues -> Option A

4. Quick Check:

   Component spacing = Placing too close [OK]

Hint: Check spacing between parts to avoid solder bridges [OK]

Common Mistakes:

• Ignoring minimum spacing rules
• Not considering solder mask clearance
• Overcrowding components

2. Which of the following is the correct way to define a PCB trace width in a design file?

easy

A. trace_width = '0.5mm'

B. traceWidth = 0.5

C. trace_width: 0.5mm

D. trace-width = 0.5mm

Solution

1. Step 1: Review syntax for trace width setting

   Trace width is often set as a string with units, e.g., '0.5mm'.

2. Step 2: Identify correct syntax

   trace_width = '0.5mm' uses correct assignment with units in quotes.

3. Final Answer:

   trace_width = '0.5mm' -> Option A

4. Quick Check:

   Trace width syntax = '0.5mm' string [OK]

Hint: Use quotes and units for trace width values [OK]

Common Mistakes:

• Omitting units in trace width
• Using invalid variable names
• Missing quotes around string values

3. Given a PCB layout with power and ground traces routed too thin, what is the most likely outcome?

medium

A. Improved signal integrity

B. Reduced electromagnetic interference

C. Increased risk of trace overheating and voltage drop

D. Better mechanical strength of the PCB

Solution

1. Step 1: Understand effects of thin power/ground traces

   Thin traces have higher resistance causing heat and voltage drop.

2. Step 2: Identify the outcome

   Higher resistance leads to overheating and unstable power delivery.

3. Final Answer:

   Increased risk of trace overheating and voltage drop -> Option C

4. Quick Check:

   Thin traces = Overheating & voltage drop [OK]

Hint: Thin power traces cause heat and voltage issues [OK]

Common Mistakes:

• Ignoring current capacity for trace width
• Assuming thin traces are always fine
• Not checking voltage drop in design

4. A PCB designer wrote the netlist but forgot to connect the ground pins of multiple components. What is the best way to fix this error?

medium

A. Change component footprints to larger sizes

B. Increase the trace width of power lines

C. Remove all ground connections to avoid confusion

D. Add a ground plane or connect ground pins with traces

Solution

1. Step 1: Identify the missing connection problem

   Ground pins must be connected to a common ground reference.

2. Step 2: Fix by adding ground plane or traces

   Adding a ground plane or connecting ground pins with traces ensures proper grounding.

3. Final Answer:

   Add a ground plane or connect ground pins with traces -> Option D

4. Quick Check:

   Ground connection fix = Add ground plane/traces [OK]

Hint: Connect all ground pins to a common ground plane [OK]

Common Mistakes:

• Forgetting to connect ground pins
• Assuming power lines replace ground
• Ignoring netlist errors

5. You notice that your PCB design has overlapping vias and traces causing short circuits. What is the best approach to solve this problem while maintaining signal integrity?

hard

A. Increase the number of vias in the overlapping area

B. Re-route traces to avoid via overlap and use design rule checks

C. Ignore the overlap if the PCB passed electrical tests

D. Use thinner traces to fit between vias

Solution

1. Step 1: Identify the cause of short circuits

   Overlapping vias and traces cause electrical shorts and signal problems.

2. Step 2: Apply design rule checks and re-route

   Re-routing traces to avoid overlaps and running design rule checks prevents shorts and maintains signal quality.

3. Final Answer:

   Re-route traces to avoid via overlap and use design rule checks -> Option B

4. Quick Check:

   Fix overlap = Re-route + design rule checks [OK]

Hint: Use design rule checks and re-route to fix overlaps [OK]

Common Mistakes:

• Ignoring via and trace overlaps
• Adding more vias without fixing routing
• Using thinner traces causing signal loss