What is a printed circuit board in PCB Design - Practice Questions & Exercises

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding the Basic Function of a Printed Circuit Board (PCB)

Which of the following best describes the primary function of a printed circuit board (PCB)?

A A wireless communication device for transmitting signals.

B A software tool used to design electronic circuits virtually.

C A board that physically supports and electrically connects electronic components using conductive pathways.

D A type of battery used to power electronic devices.

💡 Hint

Think about what holds and connects electronic parts inside devices.

A PCB is a physical board that holds electronic components and connects them with copper traces, enabling the device to function.

🧠 Conceptual

intermediate

Materials Used in Printed Circuit Boards

What is the most common base material used to make a printed circuit board?

A Silicon wafer

B Fiberglass reinforced epoxy resin

C Pure copper sheet

D Plastic film

💡 Hint

It is a strong, insulating material often used in construction.

Most PCBs use fiberglass reinforced epoxy resin as the base because it is strong, insulating, and stable.

❓ data_modeling

advanced

Layer Structure of a Multi-layer PCB

Which option correctly lists the typical layers of a multi-layer PCB from top to bottom?

A Substrate, copper layer, solder mask, copper layer, substrate

B Copper layer, solder mask, substrate, solder mask, copper layer

C Solder mask, substrate, copper layer, solder mask, copper layer

D Solder mask, copper layer, substrate, copper layer, solder mask

💡 Hint

Think about protective layers on the outside and conductive layers inside.

A multi-layer PCB typically has solder mask on the outside, copper layers beneath it, and a substrate in the middle.

🎯 Scenario

advanced

Troubleshooting a Faulty PCB Connection

You have a PCB where a component is not receiving power. Which of the following is the most likely cause?

A A broken or missing copper trace between the power source and the component.

B The component is placed on the wrong side of the board.

C The substrate material is too flexible.

D The solder mask is too thick on the component pads.

💡 Hint

Consider what physically connects the power to the component.

If the copper trace is broken or missing, the electrical connection is interrupted, so the component won't get power.

🔧 Formula Fix

expert

Identifying the Cause of Signal Interference on a PCB

A PCB design is experiencing unexpected signal interference. Which design mistake is most likely causing this issue?

A Placing high-speed signal traces too close to noisy power lines without proper grounding.

B Using wide copper traces for high-frequency signals.

C Applying solder mask over all copper traces.

D Using a multi-layer PCB instead of a single-layer PCB.

💡 Hint

Think about how signals can affect each other when placed too close.

High-speed signals placed near noisy power lines without good grounding can cause interference due to electromagnetic coupling.

Practice

1. What is the main purpose of a printed circuit board (PCB)?

easy

A. To display images on a screen

B. To store electrical energy like a battery

C. To act as a power source for devices

D. To connect electronic components using copper paths

Solution

1. Step 1: Understand PCB function

   A PCB connects electronic parts using copper paths instead of wires.

2. Step 2: Eliminate unrelated options

   PCBs do not store energy, provide power, or display images.

3. Final Answer:

   To connect electronic components using copper paths -> Option D

4. Quick Check:

   PCB = Connect components [OK]

Hint: PCBs replace wires with copper paths [OK]

Common Mistakes:

• Thinking PCB stores energy
• Confusing PCB with power source
• Assuming PCB displays images

2. Which of the following is the correct description of a PCB layer?

easy

A. A layer is a sheet of plastic that holds components

B. A layer is a copper path that connects parts electrically

C. A layer is a battery inside the board

D. A layer is a screen that shows circuit diagrams

Solution

1. Step 1: Define PCB layer

   A PCB layer is a copper path that connects electronic parts electrically.

2. Step 2: Remove incorrect options

   Layers are not plastic sheets holding parts, batteries, or screens.

3. Final Answer:

   A copper path that connects parts electrically -> Option B

4. Quick Check:

   PCB layer = Copper path [OK]

Hint: Layers are copper paths, not plastic or batteries [OK]

Common Mistakes:

• Confusing layers with plastic sheets
• Thinking layers are batteries
• Assuming layers display images

3. If a PCB has 4 layers, which of the following is true?

medium

A. It has 4 screens to display information

B. It has 4 batteries inside the board

C. It has 4 separate copper paths stacked inside

D. It has 4 plastic sheets without copper

Solution

1. Step 1: Understand multi-layer PCB

   A 4-layer PCB means 4 copper layers stacked to connect parts.

2. Step 2: Exclude wrong options

   PCBs do not contain batteries, screens, or just plastic sheets without copper.

3. Final Answer:

   It has 4 separate copper paths stacked inside -> Option C

4. Quick Check:

   4-layer PCB = 4 copper layers [OK]

Hint: Layers mean copper paths stacked, not batteries or screens [OK]

Common Mistakes:

• Thinking layers are batteries
• Assuming layers are screens
• Ignoring copper in layers

4. A PCB design file shows copper paths but no connections between components. What is likely the problem?

medium

A. The copper paths are not properly connected to component pads

B. The PCB has too many layers

C. The components are missing from the board

D. The PCB is made of plastic only

Solution

1. Step 1: Analyze missing connections

   If copper paths exist but no connections, paths may not touch component pads.

2. Step 2: Rule out other causes

   Too many layers or missing components do not cause copper paths to disconnect; plastic only means no copper.

3. Final Answer:

   The copper paths are not properly connected to component pads -> Option A

4. Quick Check:

   Disconnected copper paths = No pad connection [OK]

Hint: Check copper paths connect to pads, not just present [OK]

Common Mistakes:

• Blaming too many layers
• Assuming components missing cause copper disconnect
• Thinking PCB is plastic only

5. You need a PCB for a small wearable device that must be very thin and flexible. Which PCB type should you choose?

hard

A. Flexible PCB made with thin copper and plastic

B. Rigid PCB with multiple thick layers

C. Single-layer PCB with heavy copper

D. PCB made only of plastic without copper

Solution

1. Step 1: Identify device needs

   The device needs a thin, flexible PCB to fit wearable design.

2. Step 2: Match PCB type

   Flexible PCBs use thin copper and plastic to bend without breaking.

3. Step 3: Exclude unsuitable types

   Rigid PCBs are thick and not flexible; plastic-only PCBs lack copper paths.

4. Final Answer:

   Flexible PCB made with thin copper and plastic -> Option A

5. Quick Check:

   Wearable device = Flexible PCB [OK]

Hint: Wearables need flexible, thin PCBs [OK]

Common Mistakes:

• Choosing rigid PCBs for flexible needs
• Ignoring copper in PCB
• Selecting plastic-only boards