IPC CID+ UPDATED ACTUAL QUESTIONS
AND CORRECT ANSWERS COMPLETE
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.
AND CORRECT ANSWERS COMPLETE
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.
