CIS Component Identification & Handling 3 — Questions and Answers
Question 1: What does MSL 3 indicate for a moisture-sensitive component?
- The component can be exposed to ambient conditions for 168 hours
- The component must be stored at 30°C/60% RH and used within 168 hours of opening (Correct answer)
- The component requires baking before use regardless of storage time
- The component has unlimited floor life at room temperature
Correct answer: The component must be stored at 30°C/60% RH and used within 168 hours of opening
MSL 3 per J-STD-020 allows a floor life of 168 hours at ≤30°C/60% RH after removal from dry packaging before soldering must occur.
Question 2: Which marking system is used on SMD resistors to identify their value in a three-digit code, such as '472'?
- EIA-96 code
- Standard three-digit EIA code where the third digit is the multiplier (Correct answer)
- IPC component code
- Military part number system
Correct answer: Standard three-digit EIA code where the third digit is the multiplier
In the standard three-digit SMD marking, the first two digits are significant figures and the third is the power-of-10 multiplier, so '472' = 47 × 10² = 4,700 ohms.
Question 3: What is the significance of a white dot or painted stripe on an electrolytic capacitor?
- It indicates the positive terminal
- It indicates the negative terminal (Correct answer)
- It marks the highest capacitance end
- It identifies the manufacturer's country of origin
Correct answer: It indicates the negative terminal
On electrolytic capacitors, the stripe or marking (often white or colored) indicates the negative terminal, which must be oriented correctly to prevent component failure.
Question 4: How should tape-and-reel packaged components be stored when not in use to preserve component quality?
- Stored at elevated temperature to prevent moisture absorption
- Resealed in moisture barrier bags with desiccant if MSDs, stored in controlled conditions (Correct answer)
- Left on the reel exposed to ambient air
- Stored in direct sunlight to prevent mold growth
Correct answer: Resealed in moisture barrier bags with desiccant if MSDs, stored in controlled conditions
Unused tape-and-reel MSDs should be resealed in moisture barrier bags with fresh desiccant and humidity indicator cards, stored per J-STD-033 requirements.
Question 5: What does the 'JEDEC' polarity marking on a SOT-23 transistor package typically consist of?
- A colored band around the package
- A molded dot or alphanumeric code on the package surface (Correct answer)
- Longer lead length for the collector
- A recessed groove along one edge
Correct answer: A molded dot or alphanumeric code on the package surface
SOT-23 packages use a molded dot, embossed mark, or alphanumeric date/type code on the package surface to identify pin orientation per JEDEC TO-236 standards.
Question 6: Which of the following describes 'counterfeit component' indicators that should prompt rejection?
- Components with date codes matching the purchase order
- Mismatched lot codes, sanded or re-marked surfaces, and inconsistent font styles (Correct answer)
- Components with lead-free (Pb-free) markings
- Components supplied in original manufacturer packaging
Correct answer: Mismatched lot codes, sanded or re-marked surfaces, and inconsistent font styles
Counterfeit indicators include sanded or blacktopped surfaces (signs of re-marking), inconsistent fonts, mismatched lot codes, and anomalies detectable under magnification per AS6081.
Question 7: A component's date code reads '2247'. What does this indicate?
- The component was manufactured in 2022, week 47 (Correct answer)
- The component expires in 2247
- The component was made in week 22, year 2047
- This is a military specification code, not a date
Correct answer: The component was manufactured in 2022, week 47
A four-digit YYWW date code of '2247' means the component was manufactured in year 2022, week 47 — a standard industry convention for traceability.
CIS Component Identification & Handling 3
What does MSL 3 indicate for a moisture-sensitive component?