Semiconductor Device Electrode Segmentation for Solder and Wire Bonding
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Solution Overview
Problem
Existing semiconductor devices face challenges in achieving simultaneous high adhesive strengths to both solder and wiring, while also optimizing heat radiation properties.
Innovation Solution
The semiconductor device features a lower and upper electrode layer with different materials on their surfaces, allowing for a bonding region exposed to attach a lead wire and an adhesive layer for secure bonding, enabling strong adhesion to both solder and wiring, and improved heat radiation through a specific structural arrangement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrodes are formed of metallic material such as nickel or copper excellent in good soldering property, then soldering property is improved, but bonding to wiring formed of metallic material such as aluminum or gold is inferior
Solution Approach 1:
The electrode is divided into multiple layers with different materials. The lower electrode layer uses nickel or copper for excellent soldering property, while the upper electrode layer uses aluminum or gold for strong bonding to wiring. This segmentation allows each layer to optimize its function independently.
Solution Approach 2:
The electrode structure employs composite materials by combining different metallic materials in layers. The lower layer uses materials excellent in soldering (nickel, copper) while the upper layer uses materials with high adhesive strength to wiring (aluminum, gold), creating a composite electrode that achieves both properties simultaneously.
2Strength
If electrodes are formed of metallic material such as aluminum indicating a high adhesive strength to wiring, then bonding strength to wiring is improved, but bonding or wetting to solder consisting of metallic material such as lead or tin is inferior
Solution Approach 1:
The electrode is segmented into functional layers: the upper electrode layer uses aluminum or gold for strong wiring bonding, while the lower electrode layer uses nickel or copper for excellent solder wetting and bonding. This resolves the contradiction by separating the two functions into different layers.
Solution Approach 2:
A composite electrode structure is used where the upper layer provides high adhesive strength to wiring (aluminum, gold) and the lower layer provides excellent solder bonding (nickel, copper), achieving both properties in a single electrode component.
3Strength
If upper electrode layer extends to outside of cell-forming region, then bonding area for wiring is increased, but heat radiation from cell area may be reduced
Solution Approach 1:
The upper electrode layer is selectively extended only to the cell-free region outside the cell-forming region, not covering the cell area. This local extension provides additional bonding area for wiring while preserving heat radiation properties of the cell region, as the extension is localized to non-critical areas.
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 configuration results in a semiconductor device with enhanced bonding strengths to both solder and wiring, along with improved heat radiation properties, ensuring a reliable and efficient semiconductor device.
Implementation Method 1
an adhesive layer (7) for bonding upper electrode layer (6) and upper semiconducting element (2)
Implementation Method 2
upper IGBT 2 secured on upper surface 6a of upper electrode layer 6 by a solder layer 7 as an adhesive layer
Data Source
Figure 1~2
Figure 3~4
Figure 5~8
AI summary
A reliable semiconductor device is provided which comprises lower and upper IGBTs 1 and 2 preferably bonded to each other by solder, and a wire strongly connected to lower IGBT 1. The semiconductor device comprises a lower IGBT 1, a lower electrode layer 5 secured on lower IGBT 1, an upper electrode layer 6 secured on lower electrode layer 5, an upper IGBT 2 secured on upper electrode layer 6, and a solder layer 7 which connects upper electrode layer 6 and upper IGBT 2. Lower and upper electrode layers 5 and 6 are formed of different materials from each other, and upper electrode layer 6 has a notch 36 to partly define on an upper surface 5a of lower electrode layer 5 a bonding region 15 exposed to the outside through notch 36 so that one end of a wire 8 is connected to bonding region 15. Upper electrode layer 6 can be formed of one material superior in soldering, and also, lower electrode layer 5 can be formed of another material having a high adhesive strength to wire 8.