Electrode Terminal Design for Power Semiconductor Modules
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Solution Overview
Problem
Existing semiconductor devices for electrical power face challenges in handling high currents while maintaining reliability and compactness, particularly due to issues with thermal stress and the need for metalization of main electrodes, which complicates the bonding process and increases module size.
Innovation Solution
An electrode terminal design featuring a first drawn-out part bonded to the main electrode and a second drawn-out part formed as a plate member with a gap, allowing for ultrasonic or vacuum bonding without metalizing the main electrode, thereby reducing thermal stress and module size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a wide-width aluminum ribbon is used to increase current capacity, then productivity is improved, but heat generation increases and the module size becomes large
Solution Approach 1:
The aluminum ribbon is segmented into a first drawn-out part and a second drawn-out part that are bonded together at an intermediate position. The first part contacts the main electrode while the second part extends to the external terminal, allowing the ribbon to be drawn out without requiring additional bus-bars or ceramic board extensions, thus reducing module size while maintaining high current capacity
Solution Approach 2:
The aluminum ribbon is formed in a bent shape with portions extending in different directions (dimensions) from the main electrode. This spatial arrangement allows the ribbon to reach external terminals without increasing the ceramic board area, effectively utilizing three-dimensional space to reduce overall module footprint
2Stability of the object's composition
If a clad ribbon in arch shape is bonded by ultrasonic bonding, then the ribbon can be self-sustaining, but the bonded portion is covered by the electrode plate making inspection difficult
Solution Approach 1:
The aluminum ribbon is divided into multiple bonded portions along its length, with each portion bonded at different locations. This segmentation allows certain bonded portions to remain exposed or accessible for inspection while other portions are covered, enabling quality verification without compromising the ribbon's structural stability
Solution Approach 2:
The electrode plate serves as an intermediary element that can be positioned to cover certain bonded portions while leaving others accessible. This allows the electrode plate configuration to simultaneously provide electrical connection and enable inspection access to critical bonded areas
3Ease of manufacture
If the main electrode is metalized with copper or nickel plating for solder bonding, then solder bonding is enabled, but the process becomes complicated
Solution Approach 1:
The invention extracts the metalization step from the manufacturing process by using ultrasonic bonding instead of solder bonding. This eliminates the need for copper or nickel plating on the aluminum main electrode, simplifying the process while enabling direct bonding of the aluminum ribbon to the aluminum electrode
Solution Approach 2:
The invention replaces the thermal-chemical solder bonding process with a mechanical ultrasonic bonding process. This substitution eliminates the need for metalization layers and complex plating procedures, using mechanical vibration and pressure to create direct metal-to-metal bonds between the aluminum ribbon and aluminum electrode
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 enables the formation of a high-current power line that is reliable and compact, without the need for extra space on the board, effectively addressing the challenges of thermal stress and bonding complexity.
Implementation Method 1
a first drawn-out part 621 to be bonded to the main electrode; wherein the first drawn-out part 621 is formed so that the portion to be bonded to the main electrode is away from the opposing surface
Data Source
AI summary
An electrode terminal includes: a first drawn-out part to be bonded to a main electrode; and a second drawn-out part that is formed of a plate member in a continuous fashion from one end portion to be positioned opposite to the main electrode with a gap therebetween until another end portion to be connected to an external circuit, so that a portion in the first drawn-out part that is adjacent to a portion therein to be bonded to the main electrode, is bonded to an opposing surface to the main electrode in said one end portion; wherein the first drawn-out part is formed so that the portion to be bonded to the main electrode is away from the opposing surface; and wherein an opening portion corresponding to the main electrode is formed in the second drawn-out part.