3D Stacked Leadframe Modules for Compact Power Converters
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional power converter systems face challenges in miniaturization, flexibility, and cost reduction due to the dominance of large packaged inductors, which occupy significant board space and introduce parasitic resistances and inductances, limiting their ability to efficiently switch power and adapt to varying customer demands.
Innovation Solution
The use of vertically stacked planar leadframes with elongated leads bent away from the plane, allowing for conductive connections between layers, enabling a 3-dimensional network of components and leads that can be easily modified to meet customer specifications, reducing real estate consumption and manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional packaged inductors are used, then energy storage function is achieved, but board space consumption increases significantly
Solution Approach 1:
The patent transitions from planar 2D layout to 3D vertical stacking by bending leads away from the plane and stacking leadframes vertically. This dimensional change allows the inductor to occupy significantly less board space while maintaining its energy storage function through vertical rather than lateral arrangement.
Solution Approach 2:
The patent divides the power converter system into multiple separate leadframe modules, each containing specific components (inductor, FETs, capacitors, resistors). This segmentation allows independent optimization of each module and reduces overall parasitic effects by minimizing inter-component trace lengths within each compact leadframe.
2Adaptability or versatility
If discrete components are assembled on leadframe, then power conversion function is achieved, but manufacturing flexibility is reduced
Solution Approach 1:
The patent segments the power converter into modular leadframe units, each self-contained with specific components. This modularity enables flexible assembly configurations and easy adaptation to different customer specifications by selecting and combining different module types without redesigning the entire system.
Solution Approach 2:
The leadframe structure serves multiple functions simultaneously: it provides mechanical support for components, electrical interconnections through its conductive traces, thermal pathways for heat dissipation, and structural integrity for the packaged device. This multi-functionality reduces the need for separate components and simplifies manufacturing.
3Area of stationary object
If close proximity between inductor and FETs is used, then space is conserved, but parasitic resistances increase
Solution Approach 1:
The patent uses vertical stacking to achieve close proximity between inductor and FETs in the Z-dimension rather than lateral placement in the XY-plane. This vertical arrangement minimizes the trace length for interconnections while maintaining compact overall footprint, thereby reducing parasitic resistances despite close component spacing.
Solution Approach 2:
The patent optimizes the local trace geometry and material properties in high-current paths to minimize parasitic resistances. By carefully designing the leadframe trace width, thickness, and material composition in critical interconnection regions, the patent achieves low parasitic effects even with compact component spacing.
4Area of stationary object
If vertically stacked leadframes are used, then board space is reduced, but manufacturing complexity increases
Solution Approach 1:
The patent performs preliminary assembly of components onto leadframes before vertical stacking. This preliminary action allows standard planar assembly techniques to be used for each module separately, simplifying the manufacturing process. The bent leads are also pre-formed on the leadframes before stacking, reducing the complexity of the final assembly operation.
Solution Approach 2:
The bent leads serve as intermediaries that facilitate vertical electrical interconnection between stacked leadframes. These pre-bent leads act as mechanical and electrical mediators that simplify the stacking process by providing self-aligning connection points, reducing the need for complex alignment and bonding equipment.
Data Source
AI summary
Fabricating a packaged semiconductor device provides first planar leadframe with first leads and pads having attached electronic components. The first leadframe has a set of elongated leads bent at an angle away from the plane of the first leadframe. A second planar leadframe has second leads having attached electronic components. The bent leads of the first leadframe conductively connected to the second leadframe, forming a conductively linked 3-dimensional network between components and leads in two planes.