CIS CIS Acceptability Criteria & Defect Recognition 1 — Questions and Answers
Question 1: According to IPC-A-610, a 'process indicator' is best described as:
- A condition that causes immediate product rejection
- An anomaly that does not affect form, fit, or function but warrants monitoring (Correct answer)
- A defect requiring mandatory rework before shipment
- A critical safety hazard on the assembly
Correct answer: An anomaly that does not affect form, fit, or function but warrants monitoring
A process indicator is a condition that does not affect form, fit, or function but indicates the manufacturing process may be marginal and should be monitored.
Question 2: What is the IPC-A-610 acceptability condition for a solder bridge between two conductors that should not be electrically connected?
- Acceptable if the bridge is less than 0.5 mm wide
- Acceptable for Class 1 only
- A defect for all classes (Correct answer)
- A process indicator for Class 2 and 3
Correct answer: A defect for all classes
A solder bridge creating an unintended electrical connection between conductors is a defect for all IPC classes (1, 2, and 3).
Question 3: For IPC Class 3, a lifted land (pad lifting from the board surface) on a through-hole component is:
- Acceptable if solder joint strength is maintained
- A process indicator requiring documentation
- A defect (Correct answer)
- Acceptable if less than 25% of the land is lifted
Correct answer: A defect
For IPC Class 3 high-reliability products, any lifted land is a defect because it compromises the reliability of the solder connection.
Question 4: According to IPC-A-610, what is the maximum allowable percentage of a solder joint's height that may be voided for Class 2 SMT components?
- 10%
- 25% (Correct answer)
- 50%
- No voids allowed
Correct answer: 25%
IPC-A-610 allows up to 25% voiding by area in solder joints for Class 2 assemblies when inspected by X-ray.
Question 5: A 'cold solder joint' is characterized by:
- Excessive solder volume with good wetting
- A dull, grainy, or crystalline surface texture indicating insufficient heat during soldering (Correct answer)
- Solder that has been applied at temperatures below 100°C
- A joint with missing flux residue
Correct answer: A dull, grainy, or crystalline surface texture indicating insufficient heat during soldering
A cold solder joint has a dull, grainy, or crystalline appearance caused by inadequate heat during soldering, resulting in poor wetting and weak mechanical/electrical bonds.
Question 6: For IPC Class 2, what is the minimum acceptable solder fill percentage for a through-hole component barrel?
- 50%
- 75% (Correct answer)
- 100%
- 25%
Correct answer: 75%
IPC-A-610 requires a minimum of 75% barrel fill for through-hole solder joints in Class 2 assemblies.
CIS CIS Acceptability Criteria & Defect Recognition 1
According to IPC-A-610, a 'process indicator' is best described as: