Interdigit Leadframe Perpendicular Structure for Current Distribution
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Interdigitated leadframe pads in semiconductor devices face issues with current density, leading to risks of electromigration and limitations in circuit density and component size due to high RDSon and metal whiskering, particularly in half-bridge circuits used in power supplies and rectifiers.
Innovation Solution
A conductive leadframe with a perpendicular structure between pads and lead traces, allowing for even current distribution by decoupling current between interdigitated pads, which reduces spreading resistance and current density, and is suitable for supporting semiconductor dies with half-bridge circuits and discrete transistors like gallium nitride devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If narrow pitch is used between leadframe pads to increase circuit density, then circuit density increases, but current density increases leading to electromigration risk
Solution Approach 1:
The leadframe structure segments the current path by introducing intermediate conductive elements (such as conductive adhesive layers or additional conductive patterns) between the interdigitated pads. This segmentation distributes the current across multiple smaller current paths, reducing the current density on any single interface and thereby mitigating electromigration risk while maintaining narrow pitch for high circuit density.
2Volume of moving object
If narrow pitch is used between leadframe pads to decrease component size, then component size decreases, but RDSon increases due to leadframe characteristics
Solution Approach 1:
The invention applies local quality by optimizing the conductive properties at specific locations within the leadframe. The intermediate conductive elements are designed with higher conductivity or larger cross-section at critical current-carrying interfaces, locally improving current distribution and reducing resistance. This allows narrow pitch for compact size while maintaining low RDSon through localized conductivity enhancement.
3Ease of manufacture
If conventional parallel lead trace layout is used, then manufacturing is simplified, but current path length increases leading to higher resistance
Solution Approach 1:
The invention transitions from a conventional two-dimensional parallel lead trace layout to a three-dimensional interdigitated structure with intermediate conductive elements. This dimensional change creates multiple overlapping current paths that are vertically and horizontally distributed, significantly shortening the effective current path length and reducing package resistance while remaining compatible with standard manufacturing processes.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The perpendicular structure provides a shorter current path, reducing the risk of electromigration and RDSon, while enabling lower package resistance and effective thermal dissipation, suitable for mid to high voltage circuits.
Implementation Method 1
The perpendicular structure provides a short path for the current to travel from electrode pad openings on a device to the lead traces carrying current to other portions of a circuit
Implementation Method 2
The bottom half-etched conductive pad is further configured to be parallel to the electrode pad opening to lower spreading resistance
Data Source
Figure 1A~1C
Figure 2A~2B
Figure 3
AI summary
In an embodiment, a device comprises a lateral conduction die and a conductive leadframe. The lateral conduction die includes a plurality of parallel spaced and interleaved electrode openings on a surface of the die. The conductive leadframe may comprise a first plane and a second plane, a plurality of parallel spaced and interleaved conductive pads on the first plane of the conductive leadframe, wherein respective conductive pad of the plurality of conductive pads defines a major axis of the respective conductive pad, and a plurality of parallel conductors on the second plane of the conductive leadframe, wherein a respective conductor of the plurality of parallel conductors defines a major axis of the respective conductor. The major axis of the respective conductive pad is substantially orthogonal to the major axis of the respective conductor at a location where the respective conductive pad electrically connects to the respective conductor.