Electronic Device Mounting Structure with Dummy Electrode for Thermal Stress Management
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Solution Overview
Problem
Conventional semiconductor devices face issues with cracks in the solder layer and unintentional electrical connections due to thermal expansion and misalignment of components, leading to potential failures and reliability concerns.
Innovation Solution
The electronic device incorporates a dummy electrode and specific electrode configurations, including recessed parts and sloping surfaces, to distribute thermal stress and prevent cracks, while ensuring electrical insulation and secure connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a semiconductor chip is mounted on a die pad with solder, then electrical connection is established, but cracks occur in the solder layer due to thermal expansion and contraction
Solution Approach 1:
The patent changes the physical parameters of the solder layer by creating a concave portion that increases the surface area and alters the stress distribution. This geometric parameter change allows the solder to better accommodate thermal expansion and contraction forces, preventing crack formation while maintaining electrical connection stability.
Solution Approach 2:
The concave portion in the solder layer acts as a pre-designed stress absorption zone that cushions against thermal expansion and contraction forces before they can cause damage. This structural feature is built in advance to handle the repetitive thermal cycling that occurs during device operation, protecting the electrical connection from failure.
2Reliability
If an insulating joining part is interposed between the semiconductor chip and die pad, then electrical isolation is achieved, but the semiconductor chip inclines unreasonably causing unintentional electrical connection
Solution Approach 1:
The patent applies local quality by creating a concave portion only in specific areas of the solder layer where stress concentration occurs, rather than uniformly modifying the entire structure. This localized modification provides both mechanical support for proper chip alignment and electrical isolation where needed, without causing unintended connections.
3Reliability
If the sealing resin is made to cover all electrodes, then protection is improved, but cracks in the sealing resin become exposed to the outside
Solution Approach 1:
The patent uses a nested structure where the concave portion in the solder layer is positioned within the coverage area of the sealing resin. When cracks occur in the sealing resin, they are contained within the recessed area and do not expose the underlying electrodes to the external environment, maintaining protection even when the seal is compromised.
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
The solution effectively reduces the occurrence of cracks in the solder layer and prevents unintended electrical connections, enhancing the reliability and durability of the semiconductor device by managing thermal stress and maintaining electrical isolation.
Implementation Method 1
When the above conventional semiconductor device is in use, the constituent elements in the semiconductor device expand or contract with heat. Repeating such expansion/contraction gives rise to the possibility of cracks occurring in the solder joining the leads or in the sealing resin.
Data Source
AI summary
An electronic device includes an electronic element, a plurality of first sub-electrodes arrayed in a first direction, a plurality of second sub-electrodes arrayed in a second direction that is orthogonal to the first direction, a dummy electrode, and a sealing resin. The sealing resin has a resin back surface from which the plurality of first sub-electrodes, the plurality of second sub-electrodes and the dummy electrode are exposed. The plurality of second sub-electrodes are located further in the first direction than any of the plurality of first sub-electrodes. The plurality of first sub-electrodes are located further in the second direction than any of the plurality of second sub-electrodes. The dummy electrode is located further in the first direction than any of the plurality of first sub-electrodes, and is located further in the second direction than any of the plurality of second sub-electrodes.