IPC CID EXAM EXPECTED QUESTIONS WITH
VERIFIED ANSWERS
• What are the 3 vantage points of dimensioning? Answer: Mechanical
Constraints Drawing (mating the PCB with the mechanical housing),
PCB Master Drawing, QA inspection criteria (ensure conformance of
manufactured product for intended usage)
• Blind structure (as plated) with a maximum aspect ratio of 1:!
terminating on or penetrating a target land with a total length of no more
than 0.25mm measured from the structure's capture land foil to the target
land Answer: Microvia
• What characteristic of conductors can pick up wanted EMI signals,
creating an antenna? Answer: Longer and narrower traces (fatter traces
have more capacitance to a nearby ground, lower impedance)
• What should the designer consider adding to help the stencil
manufacturers? Answer: Alignment fiducials
• What ratio should you never go beyond in terms of the length-to-width
ratio? Answer: 12:!
• In regards to the reliability of a plated through hole, the stress is on
what and affects what? Answer: Stress is on the expansion in the Z-axis,
affects the strain in the barrel
,• Why would you use a washable solder mask / what is the advantage?
Answer: Washable masks are removable; they come off in a cleaning
operation
• In terms of material performance capability, how do you achieve
homogenous construction? Answer: Same material is used/only slight
variations occur between different material properties. Resin flow of the
prepreg must be consistent between the layers
• The reflow temperature for lead-free solder melts at a __ Answer:
higher temperature
• What is the benefit of copper balancing? Answer: Uniform exposure to
the etching solutions
• What is the importance of reliability? Answer: Determine the
functionality of equipment and the environment in which it is to operate
• For floor-plan flow, what is a recommended method? Answer:
• Hole solderability, thermal stress, plating thickness, layer registration,
anything related to hole condition within a 2-sided/multilayer board
Answer: Test coupon AB/R evaluation
• What can help straighten a board that does not have proper copper
, balance from bow and twist? Answer: Mechanical features like heat
sinks and stiffeners
• High resistance to the flow of direct current and can be polarized by an
electrical field Answer: Dielectric material
• What is a Thevenin termination? Answer: Parallel strategy where pair
or resistors, whose parallel combination is Zo, is used
• For surface mount and for the outer layers to be heat-resistant, what
can the manufacturer do to help this? Answer: Polyimide material can be
used for the outer layers of a multilayer while inner layers are standard
epoxy-grade product
• What is the most common size panel? Answer: 18x24in, 460x610mm
• How do long, thin boards jeopardize conductor routability? Answer:
Routing is primarily on the longitudinal axis and may cause crosstalk
and signal integrity problems
• What does low inductance between a forward signal and its return path
mean? Answer: Good flux cancellation, good containment of the
magnetic field
• What can a designer do to help reduce product failure from ESD?
Answer: Put an ESD label in silkscreen
VERIFIED ANSWERS
• What are the 3 vantage points of dimensioning? Answer: Mechanical
Constraints Drawing (mating the PCB with the mechanical housing),
PCB Master Drawing, QA inspection criteria (ensure conformance of
manufactured product for intended usage)
• Blind structure (as plated) with a maximum aspect ratio of 1:!
terminating on or penetrating a target land with a total length of no more
than 0.25mm measured from the structure's capture land foil to the target
land Answer: Microvia
• What characteristic of conductors can pick up wanted EMI signals,
creating an antenna? Answer: Longer and narrower traces (fatter traces
have more capacitance to a nearby ground, lower impedance)
• What should the designer consider adding to help the stencil
manufacturers? Answer: Alignment fiducials
• What ratio should you never go beyond in terms of the length-to-width
ratio? Answer: 12:!
• In regards to the reliability of a plated through hole, the stress is on
what and affects what? Answer: Stress is on the expansion in the Z-axis,
affects the strain in the barrel
,• Why would you use a washable solder mask / what is the advantage?
Answer: Washable masks are removable; they come off in a cleaning
operation
• In terms of material performance capability, how do you achieve
homogenous construction? Answer: Same material is used/only slight
variations occur between different material properties. Resin flow of the
prepreg must be consistent between the layers
• The reflow temperature for lead-free solder melts at a __ Answer:
higher temperature
• What is the benefit of copper balancing? Answer: Uniform exposure to
the etching solutions
• What is the importance of reliability? Answer: Determine the
functionality of equipment and the environment in which it is to operate
• For floor-plan flow, what is a recommended method? Answer:
• Hole solderability, thermal stress, plating thickness, layer registration,
anything related to hole condition within a 2-sided/multilayer board
Answer: Test coupon AB/R evaluation
• What can help straighten a board that does not have proper copper
, balance from bow and twist? Answer: Mechanical features like heat
sinks and stiffeners
• High resistance to the flow of direct current and can be polarized by an
electrical field Answer: Dielectric material
• What is a Thevenin termination? Answer: Parallel strategy where pair
or resistors, whose parallel combination is Zo, is used
• For surface mount and for the outer layers to be heat-resistant, what
can the manufacturer do to help this? Answer: Polyimide material can be
used for the outer layers of a multilayer while inner layers are standard
epoxy-grade product
• What is the most common size panel? Answer: 18x24in, 460x610mm
• How do long, thin boards jeopardize conductor routability? Answer:
Routing is primarily on the longitudinal axis and may cause crosstalk
and signal integrity problems
• What does low inductance between a forward signal and its return path
mean? Answer: Good flux cancellation, good containment of the
magnetic field
• What can a designer do to help reduce product failure from ESD?
Answer: Put an ESD label in silkscreen
