CIS Soldering Techniques & Standards 2 — Questions and Answers
Question 1: According to IPC J-STD-004, what does a flux activity designation of 'ROL0' indicate?
- Rosin-based, low activity, no halide content (Correct answer)
- Resin-based, organic, low halide
- Rosin-based, organic, high activity
- Resin, oxidized, low corrosion
Correct answer: Rosin-based, low activity, no halide content
ROL0 means Rosin (RO), Low activity (L), and halide content of 0% (0), per IPC J-STD-004 flux classification.
Question 2: What is the maximum acceptable solder mask intrusion into a solder joint on a through-hole component per IPC-A-610?
- Solder mask cannot reduce the minimum annular ring (Correct answer)
- No solder mask intrusion is permitted at all
- Up to 25% of the land area may be covered
- Up to 50% intrusion is acceptable for Class 1 only
Correct answer: Solder mask cannot reduce the minimum annular ring
Solder mask intrusion is acceptable as long as it does not reduce the minimum required annular ring below acceptance criteria.
Question 3: In IPC-A-610, which condition describes a through-hole solder joint where solder fills less than 75% of the barrel but wetting is acceptable?
- Process Indicator (Correct answer)
- Defect
- Acceptable
- Target
Correct answer: Process Indicator
A through-hole barrel fill between 50% and 75% (Class 3) or 25% and 75% (Class 1/2) with good wetting is classified as a Process Indicator.
Question 4: Which soldering iron tip shape is best suited for drag soldering fine-pitch SMT components?
- Chisel or hoof tip (Correct answer)
- Conical tip
- Bevel tip
- Knife tip
Correct answer: Chisel or hoof tip
A chisel or hoof tip provides a large flat surface ideal for drag soldering multiple fine-pitch leads in one stroke.
Question 5: Per IPC J-STD-001, what is the minimum preheat temperature requirement when hand soldering Class 3 assemblies with components sensitive to thermal shock?
- Preheat is required to minimize thermal gradients; specific temperature per manufacturer specs (Correct answer)
- No preheat is required for Class 3
- A minimum of 150°C preheat is mandatory for all Class 3 work
- Preheat to exactly 100°C before soldering
Correct answer: Preheat is required to minimize thermal gradients; specific temperature per manufacturer specs
IPC J-STD-001 requires preheat to minimize thermal shock but defers specific temperatures to assembly documentation and component/material specifications.
Question 6: What type of solder void is considered most critical and typically a defect in BGA joints per IPC-7095?
- Voids exceeding 25% of the ball diameter located at the interface (Correct answer)
- Any void at the center of the ball
- Voids smaller than 5% of ball diameter
- Voids that appear only in X-ray inspection
Correct answer: Voids exceeding 25% of the ball diameter located at the interface
IPC-7095 classifies voids greater than 25% of ball diameter, especially at the component or board interface, as defects that compromise joint reliability.
Question 7: Which cleanliness test method measures ionic contamination on a PCB assembly after soldering?
- ROSE (Resistivity of Solvent Extract) test (Correct answer)
- FTIR spectroscopy
- SEM/EDX analysis
- Cross-section analysis
Correct answer: ROSE (Resistivity of Solvent Extract) test
The ROSE test (also known as the Omega-meter test) measures ionic contamination by dissolving surface residues in isopropyl alcohol/water and measuring resistivity change.
CIS Soldering Techniques & Standards 2
According to IPC J-STD-004, what does a flux activity designation of 'ROL0' indicate?