Lead Frame Creepage Distance via Corner Finger Removal
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Solution Overview
Problem
Lead-frame-based semiconductor die packages often fail to meet the minimum creepage distance requirement, especially in high voltage applications, due to the reduced creepage distance caused by tie bar structures within the package body.
Innovation Solution
The solution involves modifying the lead frame design by removing one or more corner lead fingers to increase the creepage distance without altering the pitch of the remaining leads, and implementing a non-conductive support structure to maintain structural integrity for the die pad.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If tie bar structures are included in the lead frame to provide structural support, then structural integrity is improved, but creepage distance is reduced
Solution Approach 1:
The patent removes one or more corner lead fingers from the lead frame structure. This extraction of specific components eliminates the interference of tie bar structures with the creepage path, thereby increasing the creepage distance between oppositely disposed leads while maintaining structural integrity through the remaining lead frame configuration.
2Length of moving object
If corner lead fingers are removed to increase creepage distance, then creepage distance is improved, but structural support for die pad is reduced
Solution Approach 1:
The patent creates an asymmetric lead frame configuration by selectively removing corner lead fingers. This asymmetric design allows the remaining lead fingers and tie bar structures to be strategically positioned to provide adequate structural support for the die pad while maximizing the creepage distance between oppositely disposed leads.
3Reliability
If lead frame structure is modified to increase creepage distance, then electrical isolation is improved, but device complexity increases
Solution Approach 1:
Instead of adding complex insulating structures to increase creepage distance, the patent inverts the approach by removing conductive elements (corner lead fingers) from the lead frame. This simplification naturally increases the creepage distance and improves electrical isolation between leads without requiring additional insulating components or complex modifications.
Data Source
AI summary
Embodiments of a lead frame and packaged devices thereof, including a lead frame first and second rows of lead fingers respectively connected to first and second sides of the lead frame, the second side opposite the first side; a package body perimeter within which a package body of the packaged semiconductor device is formed; and a first die pad arm, wherein an end of the first die pad arm remains within the package body perimeter and is separated from the package body perimeter by a gap distance; wherein a first outermost lead finger of the first row of lead fingers is adjacent to the first die pad arm.