CIS CIS Cleaning & Contamination Control

Question 1

Which IPC standard governs cleaning and cleanliness of electronic assemblies?

Accepted Answer

IPC-CH-65

Answer

IPC-A-610

Answer

IPC-7711

Answer

IPC-2221

Question 2

What is the primary purpose of flux in the soldering process, and why must residues be managed?

Accepted Answer

Flux removes oxides to promote solder wetting; ionic residues can cause corrosion and leakage currents if not cleaned

Answer

Flux improves heat transfer; residues can crack solder joints when hardened

Answer

Flux acts as a bonding agent; residues increase mechanical strength of joints

Answer

Flux prevents tombstoning; residues attract moisture and cause delamination

Question 3

The ROSE (Resistivity of Solvent Extract) test measures:

Accepted Answer

The ionic contamination level on a printed board assembly

Answer

The thickness of solder mask coating on the PCB surface

Answer

The residual flux activity after reflow soldering

Answer

The resistance of conformal coating to solvent attack

Question 4

What is 'no-clean' flux, and when is cleaning still recommended?

Accepted 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

Answer

Flux that contains no activators; cleaning is never needed

Answer

Flux removed by the PCB laminate; cleaning is needed only when the flux is visible

Answer

Aqueous flux that self-rinses; cleaning is recommended after wave soldering only

Question 5

Which cleaning agent type is most commonly used in modern aqueous PCB cleaning systems?

Accepted Answer

Saponifiers in hot DI water

Answer

Chlorinated solvents

Answer

Isopropyl alcohol (IPA) spray

Answer

Vapor-phase trichloroethylene

Question 6

What does a white residue on a PCB assembly after soldering most likely indicate?

Accepted Answer

Incompletely activated or thermally degraded flux residue

Answer

Silver migration from component leads

Answer

Copper oxidation from insufficient solder coverage

Answer

Lead-free solder oxidation products