CIS Cleaning & Contamination Control Flashcards
6 cards from real CIS practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 CIS Cleaning & Contamination Control flashcards as text
Which IPC standard governs cleaning and cleanliness of electronic assemblies?
Answer: IPC-CH-65
IPC-CH-65 (Guidelines for Cleaning of Printed Board Assemblies) provides guidance on cleaning processes and cleanliness verification for electronic assemblies.
What is the primary purpose of flux in the soldering process, and why must residues be managed?
Answer: Flux removes oxides to promote solder wetting; ionic residues can cause corrosion and leakage currents if not cleaned
Flux removes oxides to enable proper solder wetting; however, ionic flux residues left on the board can absorb moisture and cause electrochemical corrosion and leakage currents.
The ROSE (Resistivity of Solvent Extract) test measures:
Answer: The ionic contamination level on a printed board assembly
The ROSE test measures the ionic contamination level on a PCB assembly by extracting ionic residues with a solvent-water mixture and measuring the resulting resistivity change.
What is 'no-clean' flux, and when is cleaning still recommended?
Answer: Low-residue flux designed to leave benign residues; cleaning is still recommended for high-reliability Class 3 assemblies or when residues are under components
No-clean flux leaves minimal, low-ionic residues considered safe for most applications, but high-reliability Class 3 assemblies or residues trapped under low-standoff components may still require cleaning.
Which cleaning agent type is most commonly used in modern aqueous PCB cleaning systems?
Answer: Saponifiers in hot DI water
Modern aqueous cleaning systems typically use saponifiers (alkaline cleaning agents) combined with hot deionized water to remove flux residues from PCB assemblies.
What does a white residue on a PCB assembly after soldering most likely indicate?
Answer: Incompletely activated or thermally degraded flux residue
White residue after soldering typically indicates incompletely activated flux or thermally degraded flux chemistry that has left hygroscopic residues on the board surface.