IPC CID VIEW AHEAD EXAM TEST PAPER
QUESTIONS AND SOLUTIONS 100
PERCENT CORRECT
◉ Glass transition temperature (Tg) The temperature at which anamorphous polymer changes from
being a hard and relatively-brittle condition to be in a viscous or rubbery state
◉ Moisture absorption Affects dimensional stability and changes the electrical characteristic in the
material which can cause potential difficulties in assembly
◉ Immersion, electroless, and electrolytic What are the 3 general methods of plating material on
PCBs?
◉ Corrosion prevention, Improved long-term solderability What are the benefits of metallic
coatings / final(surface) finish?
◉ Immersion Plating Simplest of the wet processes; involves a simple galvanic replacement reaction;
the more noble metal in the solution picks up electrons from the less noble metal immersed in the
solution and plates out
◉ The thickness is limited to a very thin coating as it is a simple replacement reaction Why would you
use immersion plating?
◉ Immersion has a flatter base for attachment Why is Immersion finishes more beneficial than HASL?
◉ Coplanarity / solder thickness varies, solder crowning, less uniformity What are the assembly
challenges/problems with HASL process?
◉ Gasketing Stencil fits flat on pad, opening is smaller than the land pattern in all dimensions
,◉ Uneven surfaces cause leakage of paste underneath the stencil What is the problem with
gasketing in HASL?
◉ Gray tin, nickel/gold, nickel/palladium gold, immersion "white" tin, immersion silver, ENIG What
other surface finishes are better/flatter than HASL?
◉ ENIG What surface finish is good for BGAs and surface mount?
◉ Washable masks are removable; they come off in a cleaning operation Why would you use a
washable solder mask / what is the advantage?
◉ Process to ensure that plated through holes are prevent from being contaminated by the assembly
cleaning and plating process chemistries What is plugging?
◉ Plugging For liquid photo imageable masks, what via process does IPC recommend?
◉ Tenting For dry film masks, what via process does IPC recommend?
◉ Manufacturers will mix and match the various prepreg products What will manufacturers do to
get proper flow characteristics of the prepreg material and gain better performance of the multilayer
structure?
◉ Polyimide material can be used for the outer layers of a multilayer while inner layers are standard
epoxy-grade product For surface mount and for the outer layers to be heat-resistant, what can the
manufacturer do to help this?
◉ Same material is used/only slight variations occur between different material properties. Resin flow
of the prepreg must be consistent between the layers In terms of material performance capability,
how do you achieve homogenous construction?
◉ Differences in overall resin content and the use of different styles of glass cloth; more resin/glass
content can produce the same external thickness What variation in construction change the
physical and electrical performance of pcbs?
, ◉ SPC (Statistical Process Control) Integral part of the manufacturing and testing process;
considered in all aspects during the manufaturing process and NOT confined to an evaluation at the end
of the line
◉ In-process coupon evaluation may be cross-sectioned and evaluated; first article inspection may be
performed to ensure the remainder of the lot would be in conformance What is an example of an SPC?
◉ Test coupons / specimens These specimens are representative of a the product produced and
must represent the process
◉ Provides a systematic path for continuous improvement, identifies root causes of problems, reduces
the number of evaluations that need to be made at the end of the production cycle What is the
purpose of in-process test coupons?
◉ Test coupon AB/R evaluation Hole solderability, thermal stress, plating thickness, layer registration,
anything related to hole condition within a 2-sided/multilayer board
◉ Reliability Ability of a product to function under given conditions and for a specified period of time
without exceeding acceptable failure limits
◉ Determine the functionality of equipment and the environment in which it is to operate What is
the importance of reliability?
◉ HAST Stress testing to failure, focuses on reliability
◉ Burn-in Eliminate infant mortality
◉ Product Quality Life-Cycle Tracking Identifies mechanical, physical, visual and electrical test
normally required by a customer in order to ensure that the quality life-cycle tracking data is available;
specified on applicable performance specification
QUESTIONS AND SOLUTIONS 100
PERCENT CORRECT
◉ Glass transition temperature (Tg) The temperature at which anamorphous polymer changes from
being a hard and relatively-brittle condition to be in a viscous or rubbery state
◉ Moisture absorption Affects dimensional stability and changes the electrical characteristic in the
material which can cause potential difficulties in assembly
◉ Immersion, electroless, and electrolytic What are the 3 general methods of plating material on
PCBs?
◉ Corrosion prevention, Improved long-term solderability What are the benefits of metallic
coatings / final(surface) finish?
◉ Immersion Plating Simplest of the wet processes; involves a simple galvanic replacement reaction;
the more noble metal in the solution picks up electrons from the less noble metal immersed in the
solution and plates out
◉ The thickness is limited to a very thin coating as it is a simple replacement reaction Why would you
use immersion plating?
◉ Immersion has a flatter base for attachment Why is Immersion finishes more beneficial than HASL?
◉ Coplanarity / solder thickness varies, solder crowning, less uniformity What are the assembly
challenges/problems with HASL process?
◉ Gasketing Stencil fits flat on pad, opening is smaller than the land pattern in all dimensions
,◉ Uneven surfaces cause leakage of paste underneath the stencil What is the problem with
gasketing in HASL?
◉ Gray tin, nickel/gold, nickel/palladium gold, immersion "white" tin, immersion silver, ENIG What
other surface finishes are better/flatter than HASL?
◉ ENIG What surface finish is good for BGAs and surface mount?
◉ Washable masks are removable; they come off in a cleaning operation Why would you use a
washable solder mask / what is the advantage?
◉ Process to ensure that plated through holes are prevent from being contaminated by the assembly
cleaning and plating process chemistries What is plugging?
◉ Plugging For liquid photo imageable masks, what via process does IPC recommend?
◉ Tenting For dry film masks, what via process does IPC recommend?
◉ Manufacturers will mix and match the various prepreg products What will manufacturers do to
get proper flow characteristics of the prepreg material and gain better performance of the multilayer
structure?
◉ Polyimide material can be used for the outer layers of a multilayer while inner layers are standard
epoxy-grade product For surface mount and for the outer layers to be heat-resistant, what can the
manufacturer do to help this?
◉ Same material is used/only slight variations occur between different material properties. Resin flow
of the prepreg must be consistent between the layers In terms of material performance capability,
how do you achieve homogenous construction?
◉ Differences in overall resin content and the use of different styles of glass cloth; more resin/glass
content can produce the same external thickness What variation in construction change the
physical and electrical performance of pcbs?
, ◉ SPC (Statistical Process Control) Integral part of the manufacturing and testing process;
considered in all aspects during the manufaturing process and NOT confined to an evaluation at the end
of the line
◉ In-process coupon evaluation may be cross-sectioned and evaluated; first article inspection may be
performed to ensure the remainder of the lot would be in conformance What is an example of an SPC?
◉ Test coupons / specimens These specimens are representative of a the product produced and
must represent the process
◉ Provides a systematic path for continuous improvement, identifies root causes of problems, reduces
the number of evaluations that need to be made at the end of the production cycle What is the
purpose of in-process test coupons?
◉ Test coupon AB/R evaluation Hole solderability, thermal stress, plating thickness, layer registration,
anything related to hole condition within a 2-sided/multilayer board
◉ Reliability Ability of a product to function under given conditions and for a specified period of time
without exceeding acceptable failure limits
◉ Determine the functionality of equipment and the environment in which it is to operate What is
the importance of reliability?
◉ HAST Stress testing to failure, focuses on reliability
◉ Burn-in Eliminate infant mortality
◉ Product Quality Life-Cycle Tracking Identifies mechanical, physical, visual and electrical test
normally required by a customer in order to ensure that the quality life-cycle tracking data is available;
specified on applicable performance specification
