CID Quality Control & Process Improvement 2 — Questions and Answers
Question 1: Which IPC standard defines acceptability requirements for printed boards after fabrication?
- IPC-2221
- IPC-A-600 (Correct answer)
- IPC-6012
- IPC-7711
Correct answer: IPC-A-600
IPC-A-600 establishes acceptability requirements for the visual inspection of printed boards post-fabrication.
Question 2: In Statistical Process Control (SPC), a Cpk value greater than 1.33 indicates:
- The process is out of control
- The process is capable and centered (Correct answer)
- The process mean is shifted but capable
- The process requires immediate correction
Correct answer: The process is capable and centered
A Cpk ≥ 1.33 is the industry benchmark indicating the process is both capable and sufficiently centered within its specification limits.
Question 3: What does a Fishbone (Ishikawa) diagram primarily help identify during PCB quality investigations?
- Trend data over production runs
- Root causes of a defect by category (Correct answer)
- Statistical capability of a process
- Acceptable defect limits per IPC class
Correct answer: Root causes of a defect by category
The Ishikawa diagram organizes potential root causes into categories (machines, methods, materials, etc.) to systematically identify defect sources.
Question 4: Which failure analysis technique applies voltage stress to accelerate latent defects in interconnect structures?
- HALT testing
- HAST testing (Correct answer)
- BEARS analysis
- Highly Accelerated Stress Screening (HASS)
Correct answer: HAST testing
HAST (Highly Accelerated Stress Test) uses elevated temperature, humidity, and voltage bias to accelerate corrosion and electrochemical migration failures.
Question 5: During incoming inspection of PCB laminates, which property is most critical to verify for impedance-controlled designs?
- Peel strength
- Dielectric constant (Dk) (Correct answer)
- Flammability rating
- Water absorption
Correct answer: Dielectric constant (Dk)
Dielectric constant directly determines trace impedance; variation in Dk causes impedance deviations that cannot be corrected after fabrication.
Question 6: In a DMAIC Six Sigma project addressing via drilling defects, which phase establishes the baseline defect rate?
- Define
- Measure (Correct answer)
- Analyze
- Improve
Correct answer: Measure
The Measure phase quantifies current process performance by collecting data to establish a baseline defect rate before analysis begins.
Question 7: Which chart type is best suited for monitoring the proportion of defective PCBs in variable-sized inspection lots?
- X-bar chart
- p-chart (Correct answer)
- c-chart
- R-chart
Correct answer: p-chart
The p-chart tracks the proportion of nonconforming units and automatically adjusts control limits for varying subgroup sizes.
CID Quality Control & Process Improvement 2
Which IPC standard defines acceptability requirements for printed boards after fabrication?