PCB Inspection & Diagnostics
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📘 Comprehensive Syllabus & Examination Guide
PCB Inspection & Diagnostics
Official curriculum roadmap, subject/topic distribution, negative marking rules, pacing guidelines, and solved sample questions.
🎯 Mapped Subjects & Topic Question Distribution
Total Question Pool
100%
14 MCQs
Combined Active Syllabus
PCB Inspection & Diagnostics
14 MCQs
Topic Pool
📊 Question Pool Structure
14 MCQs across fundamental, intermediate, and advanced concept tiers.
⚡ Recommended Pacing
45 to 60 seconds per MCQ. Flag complex problems and preserve 10 minutes for final revision.
⚖️ Scoring & Negative Marking
+1 mark per correct answer. In competitive tests with negative marking, -0.25 applies for incorrect guesses.
💡 Strategic Preparation & Exam Hall Guidelines
To maximize your score on PCB Inspection & Diagnostics, candidates are advised to follow a structured three-pass approach. In the First Pass, solve all direct recall and formula-based questions within 30 seconds each to secure foundational marks. In the Second Pass, tackle multi-step analytical and quantitative reasoning problems. In the Third Pass, review marked questions and verify calculations.
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Showing 10 solved representative questions
📝 Pre-Rendered Solved Sample Questions & Detailed Solutions
Review the solved problems below to understand question phrasing, answer choices, and step-by-step solution logic prior to starting the full interactive practice drill:
Sample Question 1
PCB Inspection & Diagnostics
Medium • Electronics Engineering
In PCB manufacturing and quality inspection, what does the term 'tombstoning' refer to in surface-mount technology (SMT)?
A
A chip component (resistor/capacitor) lifting on one end during reflow soldering due to unbalanced surface tension
B
Complete delamination of inner copper planes
C
Oxidation of gold plated edge contacts
D
Thermal runaway of power transistors
✓ Correct Answer: A - A chip component (resistor/capacitor) lifting on one end during reflow soldering due to unbalanced surface tension
📖 Step-by-Step Solution & Conceptual Rationale:
Tombstoning (the Manhattan effect) occurs when uneven heating or unequal solder pad geometry causes solder paste to melt faster on one end of a two-terminal chip component, pulling the component upright.
Sample Question 2
PCB Inspection & Diagnostics
Medium • Electronics Engineering
Which international standard specifies the acceptability criteria for electronic assemblies (soldering quality, component placement, cleanliness)?
A
IPC-A-610
B
ISO 9001
C
IEEE 802.3
D
ANSI C84.1
✓ Correct Answer: A - IPC-A-610
📖 Step-by-Step Solution & Conceptual Rationale:
IPC-A-610 ('Acceptability of Electronic Assemblies') is the internationally recognized benchmark standard for visual quality acceptance of soldered electronic assemblies (Class 1, Class 2, Class 3).
Sample Question 3
PCB Inspection & Diagnostics
Easy • Electronics Engineering
What is the primary cause of damage to sensitive CMOS and MOSFET components during handling and board assembly?
A
Electrostatic Discharge (ESD)
B
Ambient room lighting
C
Low atmospheric pressure
D
Normal audio acoustic vibrations
✓ Correct Answer: A - Electrostatic Discharge (ESD)
📖 Step-by-Step Solution & Conceptual Rationale:
Electrostatic Discharge (ESD) generates transient potentials of thousands of volts that puncture the microscopic thin gate oxides (SiO2) of MOSFETs and CMOS ICs, causing latent or catastrophic failure.
Sample Question 4
PCB Inspection & Diagnostics
Medium • Electronics Engineering
To safely protect electronic components against ESD damage, an ESD wrist strap must incorporate which safety feature for the human operator?
A
A 1-Megaohm current-limiting safety resistor in series with ground
B
A direct zero-ohm copper braid connection to mains earth
C
A 10-ampere fast-acting fuse
D
A step-down isolating transformer
✓ Correct Answer: A - A 1-Megaohm current-limiting safety resistor in series with ground
📖 Step-by-Step Solution & Conceptual Rationale:
ESD wrist straps always include a series 1 Mohm resistor. This allows static charges to safely bleed off to earth in milliseconds while protecting the wearer against lethal electrical shock if they accidentally touch mains voltage.
Sample Question 5
PCB Inspection & Diagnostics
Medium • Electronics Engineering
In multilayer PCB design, what is the purpose of placing dedicated, unbroken ground and power planes adjacent to signal layers?
A
To increase PCB mechanical weight
B
To provide low-inductance return current paths, minimize loop area, and suppress EMI/crosstalk
C
To allow higher soldering temperatures during manual rework
D
To eliminate the need for surface-mount components
✓ Correct Answer: B - To provide low-inductance return current paths, minimize loop area, and suppress EMI/crosstalk
📖 Step-by-Step Solution & Conceptual Rationale:
Solid plane layers provide minimal impedance return paths directly beneath high-speed signal traces, minimizing current loop areas and dramatically reducing electromagnetic radiation (EMI) and crosstalk.
Sample Question 6
PCB Inspection & Diagnostics
Easy • Electronics Engineering
What type of non-destructive diagnostic technique is used to inspect solder joints beneath Ball Grid Array (BGA) components on a PCB?
A
X-ray inspection (Automated X-ray Inspection - AXI)
B
Optical microscope
C
UV blacklight dye penetration
D
Ultrasonic immersion bath
✓ Correct Answer: A - X-ray inspection (Automated X-ray Inspection - AXI)
📖 Step-by-Step Solution & Conceptual Rationale:
Because BGA solder balls are hidden underneath the component package body, X-ray inspection (AXI) is required to detect solder bridging, voids, cold solder joints, and missing balls.
Sample Question 7
PCB Inspection & Diagnostics
Easy • Electronics Engineering
In troubleshooting printed circuit boards, what is the function of a 'thermal camera' or infrared imaging?
A
To identify shorted components, failing bypass capacitors, or overloaded ICs that generate localized hot spots
B
To measure high-frequency clock jitter
C
To verify the firmware version inside flash memory
D
To clean solder flux residue from pads
✓ Correct Answer: A - To identify shorted components, failing bypass capacitors, or overloaded ICs that generate localized hot spots
📖 Step-by-Step Solution & Conceptual Rationale:
Infrared thermal cameras quickly pinpoint shorted decoupling capacitors, internal silicon shorts, or excessive current draw by showing distinct temperature elevations (hot spots).
Sample Question 8
PCB Inspection & Diagnostics
Medium • Electronics Engineering
What is the recommended lead-free solder alloy composition commonly used in electronics assembly under RoHS compliance?
A
60% Tin / 40% Lead (Sn60/Pb40)
B
SAC305 (96.5% Tin, 3.0% Silver, 0.5% Copper)
C
50% Lead / 50% Indium
D
90% Cadmium / 10% Zinc
✓ Correct Answer: B - SAC305 (96.5% Tin, 3.0% Silver, 0.5% Copper)
📖 Step-by-Step Solution & Conceptual Rationale:
Under RoHS directives banning lead (Pb), SAC305 (Sn96.5 Ag3.0 Cu0.5) is the most widely adopted lead-free solder alloy in surface mount manufacturing, with a melting point around 217°C.
Sample Question 9
PCB Inspection & Diagnostics
Hard • Electronics Engineering
What does JTAG (Joint Test Action Group - IEEE 1149.1) boundary-scan technology enable in modern electronic board testing?
A
Testing of pin-to-pin interconnects, shorts, opens, and in-system programming of ICs without physical probe contact on pins
B
Measuring analog RF noise figure in microwave receivers
C
Increasing PCB trace current-carrying capacity by 200%
D
Generating clock signals for external switched-mode power supplies
✓ Correct Answer: A - Testing of pin-to-pin interconnects, shorts, opens, and in-system programming of ICs without physical probe contact on pins
📖 Step-by-Step Solution & Conceptual Rationale:
IEEE 1149.1 boundary-scan embeds shift-register cells at each I/O pin of ICs, allowing digital testing of continuity, traces, opens, and shorts, and firmware flashing via a simple 4- or 5-wire JTAG port.
Sample Question 10
PCB Inspection & Diagnostics
Easy • Electronics Engineering
What is the function of a decoupling (bypass) capacitor placed immediately adjacent to the Vcc pin of an integrated circuit?
A
To act as a high-frequency energy reservoir and shunt high-frequency switching noise to ground, stabilizing supply voltage
B
To increase the DC supply voltage to twice its value
C
To provide reverse polarity battery protection
D
To delay the clock signal by 90 degrees
✓ Correct Answer: A - To act as a high-frequency energy reservoir and shunt high-frequency switching noise to ground, stabilizing supply voltage
📖 Step-by-Step Solution & Conceptual Rationale:
During rapid transistor switching, ICs draw instantaneous surge currents. Decoupling capacitors (e.g. 100 nF ceramic) supply this transient charge locally, preventing voltage rail dips and radiated noise.
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