CIS CIS Cleaning & Contamination Control

Question 1

Which IPC standard governs cleaning and cleanliness of electronic assemblies?

Accepted Answer

IPC-CH-65

Answer

IPC-CH-65 (Guidelines for Cleaning of Printed Board Assemblies) provides guidance on cleaning processes and cleanliness verification for electronic assemblies.

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 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.

Question 3

The ROSE (Resistivity of Solvent Extract) test measures:

Accepted Answer

The ionic contamination level on a printed board assembly

Answer

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.

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

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.

Question 5

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

Accepted Answer

Saponifiers in hot DI water

Answer

Modern aqueous cleaning systems typically use saponifiers (alkaline cleaning agents) combined with hot deionized water to remove flux residues from PCB assemblies.

(CIS) Certified IPC Specialist Practice Test

(CIS) Certified IPC Specialist Practice Test

CIS CIS Cleaning & Contamination Control