IPC CID / COMPLETE EXAM WITH
DETAILED QUESTIONS AND
ANSWERS / GRADED A+
What do performance classes reflect?
Progressive increases in sophistication, functional performance, and
frequency/intensity of inspection or stress testing
What are the three performance classes?
1-General Electronics 2-Dedicated Service 3-High reliability
Who is the end user?
The end user is the individual or agency that contracts the printed board
or assembly to be designed and manufactured
Who determines the class of a product?
The end user
What would be in class 3 performance?
Military, medical, etc.
What is ambient temperature?
The surrounding environment that comes into contact with your product
What do producibility levels tell us?
Increasing complexity of tooling, materials, and processing. Yields
increase as costs decrease, etc.
What increases with each producibility level?
Sophisitication
What is the zaxis aspect ratio?
Ratio between the nominal thickness of the board and the smallest drill
size.
What is the most important special consideration in terms of
electrical functionality that a designer must consult the EE?
Special keep out or keep in areas of the board.
, Where should high frequency circuits be placed?
NEar the connector
Where should filtering caps be placed?
Near the source of power/gnd (at the connector)
What is least important to route in analog circuits?
Power and ground
What is a major consideration for component placement?
Will backwards compatibility be necessary?
What is Ohm's law?
V=IR
What is an important basic rule for a designer of a board?
Terminate unused logic pins with a pull-down or pull-up resistor.
What product safety testing regards flame retardants?
UL 94
How thick is half ounce copper?
0.7 mils (17 um thick)
What is the subtractive process?
Unwanted copper is etched away
What is the additive process?
Only wanted copper is added to the board
What must happen immediately after drilling the holes in the
boards?
Hole deburring
What is an unsupported hole?
A hole in the printed board that does not contain plating or other
conductive reinforcement
What is a supported hole?
A hole that has the inside surfaces plated or otherwise reinforced
What is a buried via?
A via that extends only between conductive layers with no exposure to
the outside world
How do you measure annular ring on an external layer?
Including the plating the hole.
How do you measure annular ring on an internal layer?
Excluding the plating in the hole.
What are minimum annular ring requirements defined by?
Internal supported, external supported and external unsupported holes.
What is the most important factor in determining the minimum land
size for a hole?
The max drill hole diameter
What are each of the following: a+2(b+c)+d
, Min land size=max drill hole+2(min annular
ring+etchback)+manufacturing
What is tolerance?
The amount of variation allowed in a dimension or location
What is breakout?
Drilled hole breaking out of the edge of the copper land
What is breakout acceptability?
Varies among class, where different amounts of breakout are allowed.
What is the MMC and LMC?
Can have dimensions given in a range, where MMC is most material
condition and LMC is least material condition
What is the recommended electrical spacing from board edge?
16 mils PLUS the electrical requirement
What is it called when a land is only present to balance the
construction of the board?
Nonfunctional lands
What is the clearance on nonfunctional lands?
0.25 mm (10 mils)
What is thermal relief?
Thermal relief is intended to remove sufficient copper to avoid
heatsinking during the soldering processes while still meeting minimum
current carrying requirements
How do you calculate thermal web size?
0.6(1/number of webs)landsize
What does CTE stand for and what are its units?
Coefficient of thermal expansion and ppm/C
What is the CTE for copper, brass and aluminum?
Copper: 17-18 ppm/C; brass: 19 ppm/C; aluminum: 24 ppm/C
What is special about thermal vias?
They must be connected to board-level planes
What does MTBF mean?
Mean time between failures; a higher mean time means your board is
more reliable
What is the difference between burn-in testing and HAST?
HAST is usually destructive while burn-in is non-destructive and works to
find infant mortality issues
What is a test coupon?
Companies find them beneficial and incorporate them into board
production panels to not waste a good board in production
What is true of test probes?
They must make contact with every net, and can be ensured with the
supplied net-list
DETAILED QUESTIONS AND
ANSWERS / GRADED A+
What do performance classes reflect?
Progressive increases in sophistication, functional performance, and
frequency/intensity of inspection or stress testing
What are the three performance classes?
1-General Electronics 2-Dedicated Service 3-High reliability
Who is the end user?
The end user is the individual or agency that contracts the printed board
or assembly to be designed and manufactured
Who determines the class of a product?
The end user
What would be in class 3 performance?
Military, medical, etc.
What is ambient temperature?
The surrounding environment that comes into contact with your product
What do producibility levels tell us?
Increasing complexity of tooling, materials, and processing. Yields
increase as costs decrease, etc.
What increases with each producibility level?
Sophisitication
What is the zaxis aspect ratio?
Ratio between the nominal thickness of the board and the smallest drill
size.
What is the most important special consideration in terms of
electrical functionality that a designer must consult the EE?
Special keep out or keep in areas of the board.
, Where should high frequency circuits be placed?
NEar the connector
Where should filtering caps be placed?
Near the source of power/gnd (at the connector)
What is least important to route in analog circuits?
Power and ground
What is a major consideration for component placement?
Will backwards compatibility be necessary?
What is Ohm's law?
V=IR
What is an important basic rule for a designer of a board?
Terminate unused logic pins with a pull-down or pull-up resistor.
What product safety testing regards flame retardants?
UL 94
How thick is half ounce copper?
0.7 mils (17 um thick)
What is the subtractive process?
Unwanted copper is etched away
What is the additive process?
Only wanted copper is added to the board
What must happen immediately after drilling the holes in the
boards?
Hole deburring
What is an unsupported hole?
A hole in the printed board that does not contain plating or other
conductive reinforcement
What is a supported hole?
A hole that has the inside surfaces plated or otherwise reinforced
What is a buried via?
A via that extends only between conductive layers with no exposure to
the outside world
How do you measure annular ring on an external layer?
Including the plating the hole.
How do you measure annular ring on an internal layer?
Excluding the plating in the hole.
What are minimum annular ring requirements defined by?
Internal supported, external supported and external unsupported holes.
What is the most important factor in determining the minimum land
size for a hole?
The max drill hole diameter
What are each of the following: a+2(b+c)+d
, Min land size=max drill hole+2(min annular
ring+etchback)+manufacturing
What is tolerance?
The amount of variation allowed in a dimension or location
What is breakout?
Drilled hole breaking out of the edge of the copper land
What is breakout acceptability?
Varies among class, where different amounts of breakout are allowed.
What is the MMC and LMC?
Can have dimensions given in a range, where MMC is most material
condition and LMC is least material condition
What is the recommended electrical spacing from board edge?
16 mils PLUS the electrical requirement
What is it called when a land is only present to balance the
construction of the board?
Nonfunctional lands
What is the clearance on nonfunctional lands?
0.25 mm (10 mils)
What is thermal relief?
Thermal relief is intended to remove sufficient copper to avoid
heatsinking during the soldering processes while still meeting minimum
current carrying requirements
How do you calculate thermal web size?
0.6(1/number of webs)landsize
What does CTE stand for and what are its units?
Coefficient of thermal expansion and ppm/C
What is the CTE for copper, brass and aluminum?
Copper: 17-18 ppm/C; brass: 19 ppm/C; aluminum: 24 ppm/C
What is special about thermal vias?
They must be connected to board-level planes
What does MTBF mean?
Mean time between failures; a higher mean time means your board is
more reliable
What is the difference between burn-in testing and HAST?
HAST is usually destructive while burn-in is non-destructive and works to
find infant mortality issues
What is a test coupon?
Companies find them beneficial and incorporate them into board
production panels to not waste a good board in production
What is true of test probes?
They must make contact with every net, and can be ensured with the
supplied net-list
