Semiconductor Package Lead Structure for Creepage and Board Density
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Solution Overview
Problem
Existing semiconductor packages occupy significant horizontal space on redistribution boards, limiting integration density and requiring improved reliability without increasing board space.
Innovation Solution
A semiconductor package design with leads having protruding side faces perpendicular to the semiconductor die main surfaces, featuring recesses at the leads' edges to increase electrical isolation and creepage distance, embedded in a mold compound, and optionally with exposed outer surfaces for improved heat dissipation and mechanical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the semiconductor die is arranged perpendicular to the board surface to save horizontal space, then the area occupied on the redistribution board is reduced, but the reliability of electrical isolation between power electrodes may be compromised
Solution Approach 1:
The invention transitions from horizontal arrangement to vertical arrangement by arranging the semiconductor die perpendicular to the board surface. The leads extend vertically with their outer surfaces providing contact pads on the board surface, effectively utilizing the third dimension (height) to resolve the space conflict while maintaining electrical isolation through the vertical orientation and mold compound encapsulation.
Solution Approach 2:
The mold compound acts as an intermediary material that encapsulates the leads and provides electrical isolation between the power electrodes. The mold compound fills the space around the vertically arranged leads, ensuring reliable electrical isolation while allowing the compact vertical configuration on the redistribution board.
2Reliability
If the leads are made thicker to improve electrical isolation, then the creepage distance increases, but the horizontal space occupied by the package increases
Solution Approach 1:
The invention moves the increased lead thickness from the horizontal plane to the vertical dimension. The leads are arranged vertically with increased thickness, and their outer surfaces provide contact pads on the board surface. This vertical orientation allows the thicker leads to provide adequate creepage distance without increasing the horizontal footprint of the package.
3Reliability
If the leads extend beyond the semiconductor die to provide outer contact surfaces, then the electrical isolation is improved, but the complexity of the package structure increases
Solution Approach 1:
The leads serve multiple functions: they provide electrical connection to the power electrodes, extend vertically to provide adequate creepage distance and electrical isolation, and their outer surfaces directly form the contact pads on the board surface. This multi-functionality eliminates the need for separate contact pad structures, reducing overall package complexity while maintaining improved electrical isolation.
Data Source
AI summary
A method for manufacturing a semiconductor package includes: providing a leadframe having component positions each of which includes a die pad; providing semiconductor dies each having a first power electrode on a first main surface and a second power electrode on a second main surface; mounting a respective semiconductor die onto the die pad of a respective component position of the leadframe such that the first power electrode is attached to the die pad; mounting a clip onto the dies such that the clip is attached to a respective second power electrode; embedding at least the side faces of the dies and inner surfaces of the leadframe and clip in a mold compound to form a subassembly; and cutting through the clip and leadframe at positions between neighbouring component positions.