Semiconductor Power Module with Equalized Current Paths
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Solution Overview
Problem
In semiconductor power modules, variations in current flow between semiconductor elements lead to increased size and cost due to the need for larger elements to manage junction temperature and current density constraints, especially with silicon carbide MOSFETs which are prone to crystal defects.
Innovation Solution
A semiconductor power module design where multiple semiconductor elements are connected in parallel with equalized current path lengths from electrode terminals to sources and drains, using a configuration with adjusted slit portions and reduced mounting intervals to minimize current variations, and integrated signal and detection pads for improved thermal and current management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple semiconductor elements are connected in parallel to handle high current, then current handling capability is improved, but current distribution becomes uneven leading to increased size and cost
Solution Approach 1:
The patent applies local quality by creating non-uniform current path lengths in different regions of the electrode structure. Specifically, the first electrode has different path lengths from the first electrode terminal to each semiconductor element, and the second electrode has different path lengths from each semiconductor element to the second electrode terminal. This local variation in path length compensates for the natural tendency of current to concentrate in certain elements, achieving more uniform current distribution across all parallel-connected semiconductor elements.
Solution Approach 2:
The patent changes the geometric parameters of the electrode structure, specifically the path lengths of current flow paths. By adjusting the lengths of current paths from terminals to semiconductor elements and back, the patent optimizes current distribution. The sum of path lengths (first electrode path + second electrode path) is controlled to be substantially equal for all semiconductor elements, which equalizes the impedance and achieves uniform current sharing.
2Temperature
If larger semiconductor elements are used to manage junction temperature constraints, then thermal management is improved, but element size and module cost increase
Solution Approach 1:
The patent applies local quality by providing different path lengths to different semiconductor elements based on their specific thermal and electrical characteristics. Elements that tend to carry more current are given longer path lengths to reduce their current share, while elements carrying less current receive shorter path lengths. This localized adjustment ensures that no single element is overloaded, improving thermal management across the module without requiring all elements to be oversized.
Solution Approach 2:
The patent uses temperature sensors that are positioned to detect temperatures representative of groups of semiconductor elements. By placing sensors at strategic locations (such as on the first electrode near elements with longer path lengths or on the second electrode near elements with shorter path lengths), the system can monitor thermal conditions and use this information to dynamically adjust control signals, effectively copying thermal information from critical locations to manage the entire array.
3Ease of manufacture
If non-uniform current paths are present between electrode terminals and semiconductor elements, then assembly is simplified, but current variations increase leading to waveform disorder
Solution Approach 1:
The patent applies local quality by intentionally creating specific non-uniform path lengths in controlled locations. Rather than attempting to make all paths perfectly uniform (which would be difficult and expensive), the design accepts and utilizes certain non-uniformities while compensating for them through the overall path length balancing. The first and second electrodes are designed with specific geometric features that create the required path length variations to achieve current equalization.
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 design effectively reduces semiconductor element size and module cost by suppressing current variations, enhancing thermal and current detection accuracy, and improving manufacturing yield.
Implementation Method 1
a temperature sensor that detects a temperature of the first electrode or the second electrode
Implementation Method 2
a signal terminal connected to the signal pad via a wire
Implementation Method 3
The drain side at the lower surface of the semiconductor element is joined to a metal electrode excellent in electric conductivity and thermal conductivity by solder or the like
Data Source
AI summary
An object of the present disclosure is to suppress variation in currents flowing through semiconductor elements and thereby to achieve size reduction of the semiconductor elements. The semiconductor power module includes electrode terminals for connecting a first electrode to a first external electric component, a second electrode joined to upper surfaces of a plurality of semiconductor elements, and a second electrode extension portion for connecting the second electrode to a second external electric component. The sum of a current path length from the electrode terminal to the semiconductor element in the first electrode and a current path length from the semiconductor element to a second electrode terminal portion in the second electrode, is set to be the same among the plurality of semiconductor elements.