IPC CID BUNDLED EXAMS QUESTIONS
AND ANSWERS COMPREHENSIVE STUDY
GUIDE
◉ The 3 general methods of plating material on PCBs.. Answer: Immersion, electroless, and electrolytic
◉ What are the benefits of metallic coatings / final (surface) finish.. Answer: Corrosion prevention,
Improved long-term solderability
◉ What is Immersion Plating. Answer: 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.
◉ Immersion finishes. Answer: More beneficial than HASL because immersion has a flatter base for
attachment.
◉ HASL process. Answer: Assembly challenges/problems include coplanarity / solder thickness varies,
solder crowning, less uniformity.
◉ Gasketing. Answer: Stencil fits flat on pad, opening is smaller than the land pattern in all dimensions.
◉ Gasketing in HASL. Answer: The problem is uneven surfaces cause leakage of paste underneath the
stencil.
◉ what has better/flatter surface finishes than HASL?. Answer: Gray tin, nickel/gold, nickel/palladium
gold, immersion 'white' tin, immersion silver, ENIG.
◉ ENIG. Answer: A good surface finish for BGAs and surface mount.
, ◉ What are the advantages of washable solder mask?. Answer: The advantage is that washable masks
are removable; they come off in a cleaning operation.
◉ what is plugging?. Answer: Process to ensure that plated through holes are prevented from being
contaminated by the assembly cleaning and plating process chemistries.
◉ Liquid photo imageable masks. Answer: The IPC recommends plugging as the via process.
◉ Dry film masks. Answer: The IPC recommends tenting as the via process.
◉ Manufacturers' method for proper flow characteristics. Answer: Manufacturers will mix and match
the various prepreg products.
◉ Heat-resistant outer layers. Answer: Polyimide material can be used for the outer layers of a
multilayer while inner layers are standard epoxy-grade product.
◉ Homogenous construction. Answer: Achieved by using the same material with only slight variations
occurring between different material properties; resin flow of the prepreg must be consistent between
the layers.
◉ Variation in construction. Answer: Differences in overall resin content and the use of different styles
of glass cloth; more resin/glass content can produce the same external thickness.
◉ SPC (Statistical Process Control). Answer: An integral part of the manufacturing and testing process;
considered in all aspects during the manufacturing process and NOT confined to an evaluation at the
end of the line.
◉ In-process coupon evaluation. Answer: May be cross-sectioned and evaluated; first article inspection
may be performed to ensure the remainder of the lot would be in conformance.
◉ Test coupons / specimens. Answer: These specimens are representative of the product produced and
must represent the process.
AND ANSWERS COMPREHENSIVE STUDY
GUIDE
◉ The 3 general methods of plating material on PCBs.. Answer: Immersion, electroless, and electrolytic
◉ What are the benefits of metallic coatings / final (surface) finish.. Answer: Corrosion prevention,
Improved long-term solderability
◉ What is Immersion Plating. Answer: 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.
◉ Immersion finishes. Answer: More beneficial than HASL because immersion has a flatter base for
attachment.
◉ HASL process. Answer: Assembly challenges/problems include coplanarity / solder thickness varies,
solder crowning, less uniformity.
◉ Gasketing. Answer: Stencil fits flat on pad, opening is smaller than the land pattern in all dimensions.
◉ Gasketing in HASL. Answer: The problem is uneven surfaces cause leakage of paste underneath the
stencil.
◉ what has better/flatter surface finishes than HASL?. Answer: Gray tin, nickel/gold, nickel/palladium
gold, immersion 'white' tin, immersion silver, ENIG.
◉ ENIG. Answer: A good surface finish for BGAs and surface mount.
, ◉ What are the advantages of washable solder mask?. Answer: The advantage is that washable masks
are removable; they come off in a cleaning operation.
◉ what is plugging?. Answer: Process to ensure that plated through holes are prevented from being
contaminated by the assembly cleaning and plating process chemistries.
◉ Liquid photo imageable masks. Answer: The IPC recommends plugging as the via process.
◉ Dry film masks. Answer: The IPC recommends tenting as the via process.
◉ Manufacturers' method for proper flow characteristics. Answer: Manufacturers will mix and match
the various prepreg products.
◉ Heat-resistant outer layers. Answer: Polyimide material can be used for the outer layers of a
multilayer while inner layers are standard epoxy-grade product.
◉ Homogenous construction. Answer: Achieved by using the same material with only slight variations
occurring between different material properties; resin flow of the prepreg must be consistent between
the layers.
◉ Variation in construction. Answer: Differences in overall resin content and the use of different styles
of glass cloth; more resin/glass content can produce the same external thickness.
◉ SPC (Statistical Process Control). Answer: An integral part of the manufacturing and testing process;
considered in all aspects during the manufacturing process and NOT confined to an evaluation at the
end of the line.
◉ In-process coupon evaluation. Answer: May be cross-sectioned and evaluated; first article inspection
may be performed to ensure the remainder of the lot would be in conformance.
◉ Test coupons / specimens. Answer: These specimens are representative of the product produced and
must represent the process.
