Elevated Leadframe Structure for Robust Power Package Bonding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The increasing current-carrying capacity of semiconductor power packages, particularly with wide bandgap devices like SiC and GaN, leads to mechanical challenges due to the need for more bonding wires, which reduces space for other leads and introduces manufacturing robustness issues, such as bending or vibration risks during the die attachment and wire bonding processes.
Innovation Solution
A leadframe design with elevated portions on the leads, specifically the first lead, which extends over a predetermined length in a longitudinal or lateral direction, enhances mechanical robustness by providing additional support during manufacturing processes and accommodates bonding wires or clips, thereby maintaining the package's form factor and increasing electrical connection reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of bonding wires is increased to increase current-carrying capacity, then electrical connection reliability is improved, but space for other leads is reduced and mechanical robustness deteriorates
Solution Approach 1:
The patent introduces elevation portions that extend in the vertical dimension (thickness direction) from the lead surface. This dimensional change allows the lead to gain mechanical strength and rigidity without increasing its planar footprint, thereby maintaining space for other leads while improving robustness against bending and vibration during manufacturing processes.
Solution Approach 2:
The elevation portions are selectively formed on specific leads (such as source leads or drain leads) rather than uniformly on all leads. This local enhancement provides targeted mechanical support where current-carrying capacity and manufacturing robustness are most critical, while preserving space and flexibility in other regions of the leadframe.
2Quantity of substance
If the width of leads is reduced to accommodate more bonding wires, then current density is improved, but manufacturing robustness deteriorates due to increased bending and vibration risks
Solution Approach 1:
Instead of increasing lead width in the planar direction to improve robustness, the patent adds elevation portions in the vertical dimension. This allows thin leads to maintain high current density while gaining mechanical strength through the elevated structures, preventing bending and vibration issues during die attachment and wire bonding processes.
Solution Approach 2:
The lead structure combines a thin base layer (for high current density) with elevated portions (for mechanical strength). This composite configuration allows the lead to simultaneously achieve high current-carrying capacity and manufacturing robustness, as the elevated portions act as reinforcing elements without adding significant planar width.
3Area of stationary object
If the package form factor is maintained while increasing the number of connections, then package size is controlled, but lead width must be reduced which worsens mechanical robustness
Solution Approach 1:
The patent resolves the space constraint by utilizing the vertical dimension through elevation portions. This allows the leadframe to maintain a compact planar footprint while the elevated structures provide the necessary mechanical strength, enabling more connections to be accommodated without compromising lead robustness or increasing package area.
Data Source
AI summary
A leadframe is disclosed. In one example, the leadframe comprises a die pad and a first lead comprising an inner portion and an external portion. The first lead comprises at least one elevation portion extending over a predetermined length in a longitudinal or lateral direction of the first lead. The external portion is configured to be used for external electrical connection. In another example, a semiconductor package having a leadframe is disclosed.