PCB Quality Control & Assurance 2 — Questions and Answers
Question 1: What does AOI stand for in PCB manufacturing quality control?
- Automated Optical Inspection (Correct answer)
- Analog Output Interface
- Automatic Oscillation Indicator
- Assembly Output Integration
Correct answer: Automated Optical Inspection
AOI (Automated Optical Inspection) uses cameras and image processing to detect surface defects on PCBs without electrical testing.
Question 2: Which IPC standard specifically governs acceptability of printed circuit board assemblies?
- IPC-A-600
- IPC-A-610 (Correct answer)
- IPC-2221
- IPC-7711
Correct answer: IPC-A-610
IPC-A-610 'Acceptability of Electronic Assemblies' is the most widely used electronics assembly acceptance standard in the industry.
Question 3: In IPC classification, a Class 3 PCB is intended for which application?
- Consumer electronics
- General industrial equipment
- High-reliability military and life-support systems (Correct answer)
- Prototype development only
Correct answer: High-reliability military and life-support systems
IPC Class 3 designates high-reliability products where failure cannot be tolerated, such as military, aerospace, and life-support equipment.
Question 4: What is the purpose of a first article inspection (FAI) in PCB production?
- To inspect only the first board of each production run for conformance (Correct answer)
- To verify that raw materials meet supplier specifications
- To audit the manufacturing facility annually
- To test electrical performance under thermal stress
Correct answer: To inspect only the first board of each production run for conformance
FAI verifies that the first produced unit from a new setup meets all design and specification requirements before full production proceeds.
Question 5: Measles or crazing on a PCB laminate most commonly indicates which condition?
- Copper plating voids
- Mechanical stress or thermal shock causing fiber separation (Correct answer)
- Insufficient solder mask coverage
- Electroless copper deposition failure
Correct answer: Mechanical stress or thermal shock causing fiber separation
Measles (crazing) appear as white spots within the laminate where glass fibers have separated from the resin due to mechanical or thermal stress.
Question 6: What does CPK (process capability index) measure in PCB manufacturing quality?
- The number of defects per million opportunities
- How well a process performs relative to specification limits considering centering (Correct answer)
- The ratio of actual to theoretical drill speed
- Copper thickness uniformity across the panel
Correct answer: How well a process performs relative to specification limits considering centering
CPK measures process capability while accounting for how centered the process mean is within specification limits; higher CPK indicates a more capable, centered process.
Question 7: Which defect is described as a hole in the PCB that is smaller than its design diameter after drilling?
- Breakout
- Undersize drill (Correct answer)
- Nodule
- Etch back
Correct answer: Undersize drill
An undersize drill defect occurs when the drilled hole diameter falls below the minimum tolerance specified in the design, often due to drill wear or incorrect bit selection.
PCB Quality Control & Assurance 2
What does AOI stand for in PCB manufacturing quality control?