Questions and Answers
What is the definition of 'Vertical fill' for a Class 2 defect?
What is the acceptable condition for solder on the solder source side for Class 1 and 2 defects?
Minimum 75% of land area covered with wetted solder.
What is required for the minimum wetting on lead and barrel for Class 2 defects?
Is a minimum 180° wetting on lead and barrel acceptable for a Class 1 defect?
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What is the minimum requirement for vertical fill of solder in the case of Class 2 defects?
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Which condition is considered a defect for solder in lead bend?
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Match the status of jumper wires with their descriptions:
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What should the solder termination be inspected for after lead cutting?
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For unsupported holes, at least ___% of land area must be covered with wetted solder on the secondary side.
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What is the defect classification when a lead is not discernible due to excess solder?
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The solder connection is acceptable if it is less than 75% from the edge of land to knee of lead.
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What does Through-Hole Technology entail?
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What is Connection Mounting - Orientation?
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How should nonpolarized components be oriented?
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What is the acceptable orientation for polarized parts?
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Lead is kinked in Component Mounting - Lead Forming is acceptable for Class 1.
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Leads of mounted components must extend at least one diameter from the body.
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What indicates a defect in the Component Mounting - Lead Forming?
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What is adequate stress relief in Component Mounting - Lead Forming?
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What should not exceed 10% in Component Mounting - Lead Forming?
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What happens if leads cross noncommon conductors?
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What guidelines are there for component connectors?
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Board locks should be fully inserted into the board.
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What constitutes a defect in connectors?
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Minimum fill of ___ is required for components with 14 or more leads.
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What is a defect indicated by lead not discernible in solder?
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Study Notes
Through-Hole Technology
- Ensures tool clearance for insertion/removal of hardware on electronic assemblies.
- Bonding material secures components without obscuring identification.
Connection Mounting - Orientation
- Inspections start with an overall view, concentrating on connections sequentially.
- Final step involves checking lead protrusion from underside for thorough verification.
Component Mounting - Orientation
- Horizontal (Classes 1, 2, 3): Nonpolarized components marked to be read uniformly.
- Vertical (Classes 1, 2, 3): Polarized components with long leads and nonpolarized components marked bottom-to-top.
Component Mounting - Lead Forming
- Defects: Kinked leads are unacceptable under Classes 1, 2, 3.
- Space between Seal/Weld and Bend: Acceptable when leads extend as specified; defects include fractured seals.
- Stress Relief: Camel hump bends or loop bends are acceptable under certain conditions; must not impact circuit impedance.
Component Mounting - Damage
- Acceptable if deformation is within 10% of lead dimensions; heavy indentations are classified as defects.
Leads Crossing Conductors
- Acceptable if sleeving does not obstruct solder connections; splitting or unraveling is considered a defect.
Component Mounting - Hole Obstruction
- Obstruction of primary side solder flow results in a defect, designated as a process indicator for Class 2 and defect for Class 3.
DIP/SIP Devices and Sockets
- Acceptable without excessive tilt, while a defect occurs with improper height or lead protrusion.
Radial Leads
- Vertical: Acceptable if tilt maintains electrical clearance; defects arise in unsupported scenarios.
- Horizontal: Must be in contact with the board at least on one side.
Connectors
- Modules from different suppliers should not be mixed; acceptance criteria based on insertion status and alignment conditions.
Adhesive Bonding
- Requirements include minimum contact percentages for both horizontally and vertically mounted components; defects arise from inadequate bonding.
Supported Holes and Solder
- Adequate solder coverage is critical; minimum fill and wetting requirements vary by class and component configuration.
- Solder conditions require no contact with component bodies, ensuring integrity and compliance.
Jumper Wires
- Must comply with routing guidelines to avoid insulation issues and ensure compatibility with other components.
General Guidelines
- All components must adhere to specified clearance and assembly criteria; deviations must be documented and justified without prior customer consent.### Jumper Wires - Wire Staking
- Class 1, 2, and 3 defects include uncured adhesive when used.
- Jumper wires must not stack against or touch moving parts.
Jumper Wires - Wrapped Attachment
- Requires a minimum of 90° wrapping on flat leads or 180° on round leads for acceptance.
- An acceptable solder connection must be present at the wire/lead interface.
- The contour or end of the wire should be visible in the solder connection.
- Wire overhang from component terminations must maintain minimum electrical clearance.
Jumper Wires - Lap Soldered (General)
- Solder connections must extend at least three wire diameters when the contact area is adequate.
- A minimum of 75% solder fillet is required for wires lap soldered to leads.
Jumper Wires - Lap Soldered (Class 3 Specifics)
- For Class 3, solder connection should cover 100% of the land or land/lead interface if the contact area is less than three wire diameters and is mechanically secured.
Jumper Wires - Lap Soldered Defects
- A defect occurs if the solder coverage is less than 75% from land edge to lead knee.
- Wires must not extend beyond the component lead knee.
- Lead configurations must adhere to minimum electrical clearance requirements.
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