IPC CID Exam | Detailed Review Guide
with Exam Questions and Verified
Solutions | Grade A+
‣ What is Moisture absorption? ✓✓Affects dimensional stability and
changes the electrical characteristic in the material which can cause
potential difficulties in assembly.
‣ The 3 general methods of plating material on PCBs. ✓✓Immersion,
electroless, and electrolytic
‣ What are the benefits of metallic coatings / final (surface) finish.
✓✓Corrosion prevention, Improved long-term solderability
‣ What is 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.
‣ Immersion finishes ✓✓More beneficial than HASL because immersion
has a flatter base for attachment.
‣ HASL process ✓✓Assembly challenges/problems include coplanarity /
solder thickness varies, solder crowning, less uniformity.
,‣ Gasketing ✓✓Stencil fits flat on pad, opening is smaller than the land
pattern in all dimensions.
‣ Gasketing in HASL ✓✓The problem is uneven surfaces cause leakage
of paste underneath the stencil.
‣ what has better/flatter surface finishes than HASL? ✓✓Gray tin,
nickel/gold, nickel/palladium gold, immersion 'white' tin, immersion
silver, ENIG.
‣ ENIG ✓✓A good surface finish for BGAs and surface mount.
‣ What are the advantages of washable solder mask? ✓✓The advantage
is that washable masks are removable; they come off in a cleaning
operation.
‣ what is plugging? ✓✓Process to ensure that plated through holes are
prevented from being contaminated by the assembly cleaning and
plating process chemistries.
‣ Liquid photo imageable masks ✓✓The IPC recommends plugging as
the via process.
‣ Dry film masks ✓✓The IPC recommends tenting as the via process.
, ‣ Manufacturers' method for proper flow characteristics
✓✓Manufacturers will mix and match the various prepreg products.
‣ Heat-resistant outer layers ✓✓Polyimide material can be used for the
outer layers of a multilayer while inner layers are standard epoxy-grade
product.
‣ Homogenous construction ✓✓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 ✓✓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) ✓✓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 ✓✓May be cross-sectioned and
evaluated; first article inspection may be performed to ensure the
remainder of the lot would be in conformance.
with Exam Questions and Verified
Solutions | Grade A+
‣ What is Moisture absorption? ✓✓Affects dimensional stability and
changes the electrical characteristic in the material which can cause
potential difficulties in assembly.
‣ The 3 general methods of plating material on PCBs. ✓✓Immersion,
electroless, and electrolytic
‣ What are the benefits of metallic coatings / final (surface) finish.
✓✓Corrosion prevention, Improved long-term solderability
‣ What is 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.
‣ Immersion finishes ✓✓More beneficial than HASL because immersion
has a flatter base for attachment.
‣ HASL process ✓✓Assembly challenges/problems include coplanarity /
solder thickness varies, solder crowning, less uniformity.
,‣ Gasketing ✓✓Stencil fits flat on pad, opening is smaller than the land
pattern in all dimensions.
‣ Gasketing in HASL ✓✓The problem is uneven surfaces cause leakage
of paste underneath the stencil.
‣ what has better/flatter surface finishes than HASL? ✓✓Gray tin,
nickel/gold, nickel/palladium gold, immersion 'white' tin, immersion
silver, ENIG.
‣ ENIG ✓✓A good surface finish for BGAs and surface mount.
‣ What are the advantages of washable solder mask? ✓✓The advantage
is that washable masks are removable; they come off in a cleaning
operation.
‣ what is plugging? ✓✓Process to ensure that plated through holes are
prevented from being contaminated by the assembly cleaning and
plating process chemistries.
‣ Liquid photo imageable masks ✓✓The IPC recommends plugging as
the via process.
‣ Dry film masks ✓✓The IPC recommends tenting as the via process.
, ‣ Manufacturers' method for proper flow characteristics
✓✓Manufacturers will mix and match the various prepreg products.
‣ Heat-resistant outer layers ✓✓Polyimide material can be used for the
outer layers of a multilayer while inner layers are standard epoxy-grade
product.
‣ Homogenous construction ✓✓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 ✓✓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) ✓✓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 ✓✓May be cross-sectioned and
evaluated; first article inspection may be performed to ensure the
remainder of the lot would be in conformance.
