CIS CIS PCB Design & Fabrication Standards 1 — Questions and Answers
Question 1: According to IPC-2221, what is the minimum electrical clearance required between conductors at 101–170V AC in an uncoated internal layer?
- 0.1 mm
- 0.2 mm (Correct answer)
- 0.5 mm
- 1.0 mm
Correct answer: 0.2 mm
IPC-2221 specifies 0.2 mm minimum clearance for uncoated internal conductors operating at 101–170V AC.
Question 2: Which IPC standard specifically covers the design of rigid printed boards?
- IPC-A-610
- IPC-2221 (Correct answer)
- IPC-7711
- IPC-6012
Correct answer: IPC-2221
IPC-2221 is the generic standard for the design of organic printed boards and assemblies.
Question 3: What does the term 'annular ring' refer to on a printed circuit board?
- The solder mask opening around a pad
- The copper remaining on a pad after drilling (Correct answer)
- The plating thickness inside a via
- The clearance between a via and a ground plane
Correct answer: The copper remaining on a pad after drilling
The annular ring is the portion of conductive material (copper) that remains on a pad after a hole has been drilled through it.
Question 4: IPC-6012 establishes qualification and performance requirements for which type of boards?
- Flexible printed boards
- Rigid printed boards (Correct answer)
- Rigid-flex printed boards
- Metal core printed boards
Correct answer: Rigid printed boards
IPC-6012 covers qualification and performance specification for rigid printed boards.
Question 5: What is 'controlled impedance' in PCB design?
- Maintaining consistent trace resistance across temperature
- Designing traces to a specific characteristic impedance value (Correct answer)
- Limiting current density on high-power traces
- Controlling the dielectric constant of the solder mask
Correct answer: Designing traces to a specific characteristic impedance value
Controlled impedance means designing PCB traces to achieve a specific characteristic impedance (e.g., 50Ω) to ensure signal integrity.
Question 6: According to IPC-2221, which laminate property most directly affects the dielectric constant of a PCB?
- Copper weight
- Glass transition temperature (Tg)
- Resin content (Dk) (Correct answer)
- Peel strength
Correct answer: Resin content (Dk)
The resin content and dielectric constant (Dk) of the laminate material directly determine the board's dielectric constant.
CIS CIS PCB Design & Fabrication Standards 1
According to IPC-2221, what is the minimum electrical clearance required between conductors at 101–170V AC in an uncoated internal layer?