IPC CID UPDATED ACTUAL
Exam Questions and
CORRECT Answers
SECTION 1: PCB MATERIALS & DIELECTRICS
1. The board material significantly influences the electrical performance of a circuit
through which two primary effects?
A. Thermal conductivity and moisture absorption
B. Dielectric constant and the loss tangent
C. Glass transition temperature and coefficient of thermal expansion
D. Tensile strength and flexural modulus
Answer: B
Rationale: The dielectric constant (permittivity) affects signal propagation speed and
impedance, while the loss tangent (dissipation factor) determines the amount of signal
energy lost as heat in the dielectric material .
2. What is the Glass Transition Temperature (Tg) of an amorphous polymer?
A. The temperature at which the material becomes a superconductor
B. The temperature at which the material changes from a hard, relatively brittle condition
,to a viscous or rubbery state
C. The maximum operating temperature of the PCB
D. The temperature at which the material begins to decompose
Answer: B
Rationale: Tg is the temperature at which an amorphous polymer changes from being a
hard and relatively-brittle condition to a viscous or rubbery state. This is a critical
parameter for PCB material selection .
3. What effect does moisture absorption have on PCB materials?
A. It only affects the color of the board
B. It affects dimensional stability and changes the electrical characteristics, causing
potential assembly difficulties
C. It improves the thermal conductivity of the material
D. It has no significant effect on PCB performance
Answer: B
Rationale: Moisture absorption affects dimensional stability and changes the electrical
characteristic in the material, which can cause potential difficulties in assembly .
4. What is the fastest dielectric constant and what is its value?
A. Copper, Dk ≈ 5.8
B. Air, Dk = 1
C. FR-4, Dk ≈ 4.5
D. Teflon, Dk ≈ 2.1
Answer: B
Rationale: Air has the fastest dielectric constant with a Dk value of 1. Lower dielectric
constants result in faster signal propagation speeds .
,5. For high-frequency applications, what material properties are most important?
A. Higher dielectric constants and higher dissipation factors
B. Lower dielectric constants and lower dissipation factors
C. Higher glass transition temperatures only
D. Lower moisture absorption only
Answer: B
Rationale: Lower dielectric constants and dissipation factors are important for high-
frequency applications because they provide faster conductor signal speed, shorter
propagation delay times, lower dielectric losses, and wider interconnects for the same
design impedance .
6. What does "polyimide material" allow when used on the outer layers of a multilayer
PCB?
A. Lower cost manufacturing
B. Heat resistance for surface mount components and outer layers
C. Faster signal propagation
D. Better moisture resistance
Answer: B
Rationale: Polyimide material can be used for the outer layers of a multilayer PCB while
inner layers are standard epoxy-grade product to provide heat resistance for surface
mount and outer layers .
7. What is the relationship between resin flow of prepreg and homogeneous construction?
A. Resin flow must be consistent between the layers
B. Resin flow should vary between layers
C. Resin flow is not important for homogeneous construction
D. Only the glass cloth type matters for homogeneous construction
Answer: A
, Rationale: For homogeneous construction, the same material is used with only slight
variations between different material properties. Resin flow of the prepreg must be
consistent between the layers .
8. What variation in construction can change the physical and electrical performance of
PCBs?
A. Only the type of copper foil used
B. Differences in overall resin content and the use of different styles of glass cloth
C. Only the thickness of the outer layers
D. Only the color of the solder mask
Answer: B
Rationale: Differences in overall resin content and the use of different styles of glass cloth
can produce the same external thickness but change the physical and electrical
performance of PCBs .
SECTION 2: PLATING & SURFACE FINISHES (Questions 9-24)
9. What are the three general methods of plating material on PCBs?
A. Electroplating, galvanic plating, and dip plating
B. Immersion, electroless, and electrolytic
C. Sputtering, evaporation, and chemical vapor deposition
D. Hot-dip, electroplating, and electroless
Answer: B
Rationale: The three general methods of plating material on PCBs are immersion,
electroless, and electrolytic plating .
Exam Questions and
CORRECT Answers
SECTION 1: PCB MATERIALS & DIELECTRICS
1. The board material significantly influences the electrical performance of a circuit
through which two primary effects?
A. Thermal conductivity and moisture absorption
B. Dielectric constant and the loss tangent
C. Glass transition temperature and coefficient of thermal expansion
D. Tensile strength and flexural modulus
Answer: B
Rationale: The dielectric constant (permittivity) affects signal propagation speed and
impedance, while the loss tangent (dissipation factor) determines the amount of signal
energy lost as heat in the dielectric material .
2. What is the Glass Transition Temperature (Tg) of an amorphous polymer?
A. The temperature at which the material becomes a superconductor
B. The temperature at which the material changes from a hard, relatively brittle condition
,to a viscous or rubbery state
C. The maximum operating temperature of the PCB
D. The temperature at which the material begins to decompose
Answer: B
Rationale: Tg is the temperature at which an amorphous polymer changes from being a
hard and relatively-brittle condition to a viscous or rubbery state. This is a critical
parameter for PCB material selection .
3. What effect does moisture absorption have on PCB materials?
A. It only affects the color of the board
B. It affects dimensional stability and changes the electrical characteristics, causing
potential assembly difficulties
C. It improves the thermal conductivity of the material
D. It has no significant effect on PCB performance
Answer: B
Rationale: Moisture absorption affects dimensional stability and changes the electrical
characteristic in the material, which can cause potential difficulties in assembly .
4. What is the fastest dielectric constant and what is its value?
A. Copper, Dk ≈ 5.8
B. Air, Dk = 1
C. FR-4, Dk ≈ 4.5
D. Teflon, Dk ≈ 2.1
Answer: B
Rationale: Air has the fastest dielectric constant with a Dk value of 1. Lower dielectric
constants result in faster signal propagation speeds .
,5. For high-frequency applications, what material properties are most important?
A. Higher dielectric constants and higher dissipation factors
B. Lower dielectric constants and lower dissipation factors
C. Higher glass transition temperatures only
D. Lower moisture absorption only
Answer: B
Rationale: Lower dielectric constants and dissipation factors are important for high-
frequency applications because they provide faster conductor signal speed, shorter
propagation delay times, lower dielectric losses, and wider interconnects for the same
design impedance .
6. What does "polyimide material" allow when used on the outer layers of a multilayer
PCB?
A. Lower cost manufacturing
B. Heat resistance for surface mount components and outer layers
C. Faster signal propagation
D. Better moisture resistance
Answer: B
Rationale: Polyimide material can be used for the outer layers of a multilayer PCB while
inner layers are standard epoxy-grade product to provide heat resistance for surface
mount and outer layers .
7. What is the relationship between resin flow of prepreg and homogeneous construction?
A. Resin flow must be consistent between the layers
B. Resin flow should vary between layers
C. Resin flow is not important for homogeneous construction
D. Only the glass cloth type matters for homogeneous construction
Answer: A
, Rationale: For homogeneous construction, the same material is used with only slight
variations between different material properties. Resin flow of the prepreg must be
consistent between the layers .
8. What variation in construction can change the physical and electrical performance of
PCBs?
A. Only the type of copper foil used
B. Differences in overall resin content and the use of different styles of glass cloth
C. Only the thickness of the outer layers
D. Only the color of the solder mask
Answer: B
Rationale: Differences in overall resin content and the use of different styles of glass cloth
can produce the same external thickness but change the physical and electrical
performance of PCBs .
SECTION 2: PLATING & SURFACE FINISHES (Questions 9-24)
9. What are the three general methods of plating material on PCBs?
A. Electroplating, galvanic plating, and dip plating
B. Immersion, electroless, and electrolytic
C. Sputtering, evaporation, and chemical vapor deposition
D. Hot-dip, electroplating, and electroless
Answer: B
Rationale: The three general methods of plating material on PCBs are immersion,
electroless, and electrolytic plating .
