CIS Study Guide 2026
Everything you need to pass the CIS exam in one place: the exam format, every topic to study, real practice questions with explanations, flashcards, and full-length practice tests. Free, no sign-up needed.
📋 CIS Exam Format at a Glance
📚 CIS Topics to Study (22)
✍️ Sample CIS Questions & Answers
1. What is 'pad conditioning' during SMT rework?
Pad conditioning involves cleaning residual solder from the pad, re-tinning with fresh solder if needed, and verifying the pad shape and condition before installing a replacement component.
2. What hazard does halide contamination (chlorides, bromides) pose to PCB assemblies?
Halide ions (Cl⁻, Br⁻) from flux activators are aggressive corrosion catalysts; if left on the assembly, they absorb moisture and create highly corrosive ionic solutions that accelerate metal corrosion and electrochemical migration.
3. What is a 'jumper wire' modification in PCB repair, and what IPC standard governs it?
A jumper wire is an added conductor used to replace a damaged trace or correct a wiring error; IPC-7711/7721 provides specific requirements for acceptable jumper wire installation.
4. What is the purpose of a 'rinse purity monitor' in an aqueous cleaning system?
A rinse purity monitor measures the conductivity or resistivity of final rinse water to ensure it hasn't accumulated enough ionic contamination to recontaminate boards exiting the cleaning system.
5. What conformal coating defect is described as small circular depressions or craters that expose the underlying substrate?
Fisheyes or cratering are circular depressions caused by surface tension differences, often from contamination or silicone, that pull the wet coating away from a point and expose the substrate.
6. 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?
IPC-A-610 allows up to 25% voiding by area in solder joints for Class 2 assemblies when inspected by X-ray.