Leadframe Package Layout for Compact Solder Lands and Short Prevention
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Solution Overview
Problem
Manufacturers face challenges in reducing the size of leadless semiconductor packages while maintaining minimum specifications to prevent short circuiting and ensuring suitable sized lands for soldering to a printed circuit board.
Innovation Solution
The design includes a leadframe package with a die pad and leads where the base portions of the leads are offset relative to the die pad protrusions, and the leads feature upper portions with lead locks that extend beyond the base portions, aiding in locking the die pad and leads within the encapsulation material, thereby reducing package size while maintaining adequate land size for soldering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the package size is reduced, then the compactness and integration density are improved, but the minimum distances between electrical components may be compromised leading to short circuiting risks
Solution Approach 1:
The die pad is segmented with multiple protrusions that create distinct spacing zones between electrical components. These protrusions divide the die pad surface into separated regions, ensuring minimum distances are maintained between leads and other components while still allowing a compact overall package design.
Solution Approach 2:
The protrusions are strategically positioned at specific locations on the die pad where spacing is critical. This local structural modification provides enhanced separation exactly where needed, rather than uniformly increasing the entire package size, thus maintaining compactness while ensuring reliability at critical spacing points.
2Volume of moving object
If the package size is reduced, then the compactness is improved, but the land size for soldering may be insufficient
Solution Approach 1:
The protrusions extend in the vertical dimension from the die pad surface, creating three-dimensional spacing structures. This allows horizontal land area to be maintained for adequate soldering while the vertical protrusions provide the necessary spacing to reduce overall package footprint, effectively solving the contradiction by utilizing a different dimension.
3Reliability
If the distances between electrical components are increased to prevent short circuiting, then the reliability is improved, but the package size increases
Solution Approach 1:
The protrusions segment the die pad into distinct zones, creating natural spacing barriers that prevent short circuiting between adjacent leads. This segmentation achieves the reliability goal of preventing electrical failures without requiring a uniform increase in package dimensions, as the spacing is localized to where protrusions are present.
Solution Approach 2:
The protrusions act as intermediary structures between electrical components, providing physical separation and insulation. These intermediary elements ensure minimum distances are maintained for reliability while having minimal impact on overall package size, as they only occupy the specific spaces between components rather than expanding the entire package envelope.
Data Source
AI summary
Generally described, one or more embodiments are directed to a leadframe package having a plurality of leads, a die pad, a semiconductor die coupled to the die pad, and encapsulation material. An inner portion of the die pad includes a perimeter portion that includes a plurality of protrusions that are spaced apart from each other. The protrusions aid in locking the die pad in the encapsulation material. The plurality of leads includes upper portions and base portions. The base portion of the plurality of leads are offset (or staggered) relative to the plurality of protrusions of the die pad. In particular, the base portions extend longitudinally toward the die pad and are located between respective protrusions. The upper portions of the leads include lead locks that extend beyond the base portions in a direction of adjacent leads. The lead locks and the protrusion in the die pad aid in locking the leads and the die pad in the encapsulation material.