Flexible Circuit Leadframe for Semiconductor Power Module Insulation
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Solution Overview
Problem
In high voltage semiconductor power modules, especially those with IGBTs and FETs, ensuring adequate electrical insulation between the metal leadframe and adjacent cold plates is challenging, leading to potential electrical shorting due to the close proximity of the metal leadframe to the gate terminal links.
Innovation Solution
The use of flexible circuit leadframes with selectively insulated conductor patterns, sandwiched between semiconductor chips and ceramic substrates, provides electrical insulation and access to chip terminals, allowing for double-side cooling and accommodating different chip thicknesses with separate substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal leadframe is used to access electrical terminals of the chip, then electrical connectivity is achieved, but electrical insulation between the leadframe and adjacent cold plates cannot be ensured in high voltage applications
Solution Approach 1:
The patent introduces an intermediary insulating structure between the metal leadframe and the cold plate. This insulating layer acts as a mediator that prevents direct electrical contact while maintaining thermal coupling, thereby ensuring electrical insulation without compromising the cooling function.
Solution Approach 2:
The leadframe structure is transformed into a composite material system combining conductive metal traces with insulating substrates and coating layers. This composite construction allows simultaneous achievement of electrical connectivity through metal paths and electrical insulation through the insulating matrix and protective coatings.
2Ease of operation
If the metal leadframe is placed close to the gate terminal links, then electrical access is improved, but the risk of electrical shorting increases
Solution Approach 1:
The patent applies local quality by providing insulation only in critical areas where shorting risk exists, rather than insulating the entire leadframe uniformly. The insulating coating is strategically positioned near gate terminal links and other sensitive areas, maintaining electrical access where needed while preventing shorting where hazards exist.
3Adaptability or versatility
If separate ceramic substrates are provided for each chip, then different chip thicknesses can be accommodated, but manufacturing complexity increases
Solution Approach 1:
The patent divides the module into separate ceramic substrate units, each dedicated to a specific chip. This segmentation allows each substrate to be independently manufactured and optimized for its associated chip's thickness requirements, enabling greater adaptability while simplifying the assembly process through modular construction.
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
This solution ensures reliable electrical insulation, reduces the risk of shorting, allows for thinner and more cost-effective module construction, and enables efficient heat dissipation in high voltage applications.
Implementation Method 1
an insulated jacket to ensure adequate electrical insulation between the leadframe conductor pattern and adjacent conductive surfaces
Implementation Method 2
a first ceramic substrate thermally coupled to the upper face of the chip for heat dissipation
Data Source
AI summary
A semiconductor power module includes a semiconductor chip thermally interfaced to a ceramic substrate and a leadframe defined by a flexible circuit disposed intermediate the chip and the ceramic substrate. The flexible circuit includes a conductor layer that is selectively encased in an insulated jacket to ensure adequate electrical insulation between the conductor layer and adjacent conductive surfaces. Preferably, the module is constructed for double side cooling by sandwiching the chip between a pair of ceramic substrates and providing intermediate flexible circuit leadframes on both sides of the chip for electrically accessing the chip terminals.