Segmented Electrode Lead Thermal Stress Relief
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Solution Overview
Problem
Semiconductor devices experience fatigue failure due to thermal stress at the soldered portions caused by differences in linear expansion coefficients between components, leading to potential failures in the connecting portions of the lead frame.
Innovation Solution
The semiconductor device design features an electrode lead with divided portions that can displace relative to each other, allowing for thermal stress relief through elastic deformation, and a sealing resin portion that separates these portions to reduce thermal conductivity and void formation during manufacturing, thereby minimizing fatigue failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the electrode lead is made as a single integral piece, then the structural strength is improved, but thermal stress accumulates causing fatigue failure at the soldered portion
Solution Approach 1:
The electrode lead is divided into multiple segments (first electrode lead portion and second electrode lead portion) that can move independently relative to each other. This segmentation allows each segment to accommodate thermal expansion differently, preventing stress accumulation at the soldered connection while maintaining overall structural integrity.
Solution Approach 2:
The electrode lead structure incorporates dynamic flexibility by allowing relative movement between segments. The first and second electrode lead portions can displace independently in response to thermal stress, transforming the rigid integral structure into a dynamic system that adapts to thermal expansion variations.
2Temperature
If the sealing resin has high thermal conductivity, then heat dissipation is improved, but thermal stress increases due to rapid heat transfer
Solution Approach 1:
The sealing resin is applied selectively in specific regions rather than uniformly throughout. By positioning the sealing resin to seal gaps between the electrode lead and semiconductor element without completely filling all spaces, the design achieves localized thermal management that balances heat dissipation with stress reduction.
3Ease of manufacture
If the sealing resin fills all gaps during molding, then manufacturing completeness is improved, but voids and air pockets remain causing reliability issues
Solution Approach 1:
The electrode lead is segmented into multiple portions that create defined separation zones. These segments act as barriers that prevent air entrapment during molding while ensuring complete resin filling in functional areas, thereby eliminating voids without compromising manufacturing efficiency.
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 thermal stress and fatigue failure in semiconductor devices by allowing the electrode lead portions to move relative to each other and distributing heat more evenly, resulting in a stronger and more reliable connection with reduced voids in the sealing resin.
Implementation Method 1
the plurality of portions can be displaced relative to each other along a direction transverse to a direction of division. This displacement causes thermal stress to be relieved
Implementation Method 2
This thermal stress is caused by a difference in linear expansion coefficient between components of the semiconductor device
Data Source
AI summary
A semiconductor device has a substrate, a semiconductor element, an electrode lead, and a sealing resin portion. The substrate has a main surface on which a circuit pattern is formed. The semiconductor element has first and second surfaces, and is arranged on the substrate such that the first surface faces the main surface. The electrode lead has one end joined to the circuit pattern and the other end joined by soldering to the second surface. The other end has a plurality of portions divided from each other. The sealing resin portion seals the semiconductor element and the electrode lead. Thus, there can be provided a semiconductor device that has relieved thermal stress at a joining portion of the electrode lead, and therefore is less subject to fatigue failure.