Workplace Safety, ESD Control and Occupational Health
What this domain tests
Electrical safety, static control, chemical and fume hazards, personal protective equipment and good housekeeping. Expect scenario questions about the first action to take.
Rules
- Isolate before repair: unplug, discharge capacitors, lock off where possible, and verify dead with a meter. Work one-handed where live testing is unavoidable.
- ESD damages MOS devices invisibly. Use a grounded wrist strap with a 1 MΩ series resistor, a grounded mat and grounded tool stations. Store ICs in conductive foam or antistatic bags. Keep relative humidity around 40–60%; avoid synthetic clothing and carpets.
- Solder fumes irritate the respiratory tract: use fume extraction or ventilation, keep your head out of the plume, wear safety glasses and wash hands after handling lead solder. Do not eat or drink at the bench.
- Use PPE: goggles for cutting and desoldering, gloves for chemicals, hearing protection near noisy equipment.
- Keep a fire extinguisher suitable for electrical fires, such as CO₂ or dry powder; never use water on live equipment. Know first-aid and emergency contacts.
- Ergonomics: chair height, monitor at eye level, breaks to prevent strain; 5S keeps the bench safe and findable.
Worked example
Before fitting a CMOS IC, you put on a wrist strap and clip it to the grounded bench point. You check the strap with an ESD tester; a strap reading open or short is rejected. The IC stays in its antistatic tube until the moment of insertion, and you handle the board by its edges. The iron is in its stand, not on the bench, and the fume extractor is running.
Traps
- Wearing a wrist strap that is not actually grounded.
- Touching pins or tracks directly.
- Using water on an electrical fire.
- Assuming a low-voltage bench has no electrical hazard.