Questions and Answers
What does acceptable staking adhesive look like for Class 1 components?
Adhesive materials extending from under the component are visible in the termination area for a Class 3 defect.
True
What is the minimum percentage of component height that adhesive must adhere to for round components in Class 1, 2, and 3?
25%
What is considered a defect for staking adhesive on round components?
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What happens when solder touches a plastic component body during SMT?
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A lead that is damaged more than 10% of its diameter is categorized as a Class 1 defect.
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What is the acceptable thickness of a flattened lead for Class 1 and 2 components?
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What is the minimum end joint width required for Class 3 components?
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What is the acceptable side joint length for rectangular or square end chip components?
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What is the acceptable maximum fillet height (E) for Rectangular or Square End Chip Components?
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What does minimum fillet height (F) exhibit on the vertical surface(s) of the component termination?
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What does minimum fillet height (F) consist of for Class 3?
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What is the requirement for wetted fillet in terms of solder thickness?
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End overlap (J) must always be 25% or more between the component termination and the land.
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What should the width (W) to height (H) ratio not exceed for mounting on the side?
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For components larger than size 1206, how many termination faces should they have?
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Center terminations must have a minimum side termination width of 50% of the component termination width.
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What is the acceptable value for side overhang (A) of cylindrical end cap terminations?
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What is the defect related to the end overhang (B) in cylindrical end cap terminations?
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What should be evident for the minimum heel fillet height (E) in case of a toe-down configuration?
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Surface mount area array solder connections should not make contact with the land.
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What type of overhang is unacceptable for P-Style connections?
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What aspect of flat gull wing leads is considered a defect?
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Study Notes
Staking Adhesive - Component Bonding
- Acceptable (Class 1): Adhesive material visible in termination area, with end joint width meeting minimum requirements.
- Defect (Class 3): Adhesive material visible in termination area, not meeting acceptable criteria.
Staking Adhesive - Mechanical Strength
- Acceptable (Class 1, 2, 3): On round components, adhesive covers at least 25% of component height and requires a minimum of three beads evenly placed around the component.
- Defect (Class 1, 2, 3): Fewer than three beads of staking material on round components.
SMT Leads - Plastic Components
- Solder should not contact the package body or seal unless specific lead configurations cause contact with plastic components like SOIC family.
SMT Leads - Damage
- Defect (Class 1, 2, 3): Damage or deformation to leads exceeding 10% of their diameter, width, or thickness.
SMT Connections
- Components with non-wettable areas by design are exempt from solder wetting requirements in those regions.
Chip Components - Bottom Only Terminations
- Side Overhang (Class 1, 2): Side overhang must be ≤ 50% of component termination or land width.
- End Joint Width (Class 1, 2): Minimum width must be ≥ 50% of component termination or land width.
Rectangular or Square End Chip Components
- Acceptable Side Overhang (Class 1, 2): ≤ 50% of termination or land width.
- End Joint Width (Class 3): Minimum end joint width must be ≥ 75% of termination or land width.
Cylindrical End Cap Terminations
- Referred to as MELF (Metal Electrode Leadless Face).
- Acceptable Side Overhang (Class 1, 2, 3): Must be ≤ 25% of component width or land width.
Castellated Terminations
- Acceptable Side Overhang (Class 1, 2): Maximum ≤ 50% castellation width.
- Minimum End Joint Width (Class 3): Should be ≥ 75% of castellation width.
Flat Gull Wing Leads
- Side Overhang (Class 1, 2): Maximum overhang should not exceed 50% of lead width or 0.5 mm.
- Minimum End Joint Width (Class 3): Minimum end joint width should be ≥ 75% lead width.
J-Leads
- Toe Overhang (Class 1, 2, 3): This parameter is unspecified, offering flexibility in design.
Surface Mount Area Array
- Process guidance provided in IPC-7095 with a focus on addressing process development issues.
- Solder Connections (Class 1, 2, 3): BGA solder balls must contact and wet the land to form a complete connection.
Additional Notes on Fillets and Joints
- Minimum Heel Fillet Height (Flat Gull Wing): In toe-down configurations, minimum height should extend to at least the midpoint of outside lead bends.
- End Overlap (Cylindrical Terminations): Must be ≥ 50% the length of component termination for acceptable standards.
Familiarize with the criteria detailed above for various components to ensure compliance with IPC-A-610 standards across different classes.### Components with Bottom Thermal Plane Terminations
- Thermal plate terminations are characterized by their end joint width.
- Acceptable standards include Class 1, 2, and 3.
Flattened Post Connections
- Connections should comply with dimensional and solder fillet standards as per specific tables.
- Maximum termination overhang differs based on solder land shape and class.
Maximum Termination Overhang - Square Solder Land
- Class 1: Overhang must be less than 75%.
- Class 2: Overhang must be less than 50%.
Maximum Termination Overhang - Round Solder Land
- Class 1 defect: Overhang exceeds 50%.
- Class 2 defect: Overhang exceeds 25%.
Maximum Fillet Height
- Defect classifications for Class 1 and 2 occur when solder touches the package body.
P-Style Connections - Maximum Side Overhang
- Class 1: Acceptable overhang is equal to or less than 50% of the termination width.
- Class 2: Acceptable overhang is equal to or less than 25% of the termination width.
- Class 3 requires no side overhang.
P-Style Connections - Minimum Side Overhang
- Acceptable classifications for minimum side overhang are unspecified and marked as Class.
Surface Mount Connections
- Defects in Classes 1, 2, and 3 must meet form, fit, and function requirements, often necessitating trial mating for acceptance.
Jumper Wires
- Refer to IPC-7711/7721 for guidelines on rework and repair.
- Criteria for wire includes selection, routing, and adhesive staking relevant to SMT jumper wires.
General Conditions for Lap Solder Connections
- Key conditions include insulation clearance, no fractures, and specific wire contour standards, including wire overhang regulations.
Jump Wires - SMT - Chip and Cylindrical End Cap
- Acceptable in Classes 1, 2, and 3 if properly adhered.
- A defect occurs when the wire is soldered on top of the chip component termination.
Gull Wing Configuration
- Jump wires in this configuration are acceptable across all classes ensuring proper wire extends past the knee of the bend.
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Test your knowledge on IPC-A-610 Chapter 8 with these flashcards. This quiz covers key concepts related to staking adhesive component bonding and acceptable quality levels. Perfect for anyone studying electronic assembly standards.
