Semiconductor Sealing Member Design for Thermal Stress Reduction
Solution Overview
Problem
Semiconductor devices face reliability issues due to internal stress caused by temperature changes, which lead to cracking in the sealing member due to differing linear expansion coefficients between the case and sealing member materials, reducing power cycle resistance and overall reliability.
Innovation Solution
A semiconductor device design where the sealing member's contact area is positioned closer to the semiconductor chip than its sealing surface, creating a space between the sealing member and the case's inner wall, reducing the joining area and internal stress, and incorporating a spacer jig to manage the curing process of the sealing member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sealing member is made to contact the case inner wall over a large area to ensure sealing, then sealing effectiveness is improved, but internal stress concentration increases causing cracks
Solution Approach 1:
The sealing member is designed with non-uniform cross-sectional area along its length, creating regions of different stiffness. The larger cross-section is positioned away from the case wall contact point, while the smaller cross-section contacts the case wall. This local variation in geometry allows the sealing surface to maintain effective contact for sealing while reducing stress concentration at the contact interface, preventing cracks in the sealing member.
2Adaptability or versatility
If different materials are used for the case and sealing member to achieve functional requirements, then functional performance is improved, but differential thermal expansion causes stress
Solution Approach 1:
The patent utilizes the differential thermal expansion between different materials (case and sealing member) by designing the sealing member with a specific non-uniform cross-sectional profile. This geometric parameter change compensates for the stress generated by thermal expansion differences, allowing the sealing member to accommodate temperature-induced dimensional changes without developing excessive internal stress that would cause cracking.
3Ease of manufacture
If the sealing member cross-section is uniform to simplify manufacturing, then manufacturing complexity is reduced, but stress distribution becomes uneven causing cracks
Solution Approach 1:
The sealing member incorporates a non-uniform cross-sectional area that varies along its length, with the larger cross-section positioned away from the case wall contact point and the smaller cross-section at the contact point. This local geometric variation optimizes stress distribution during thermal cycling, preventing crack initiation and propagation while maintaining effective sealing contact with the case wall.
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 the risk of cracking in the sealing member and enhances the semiconductor device's reliability against temperature changes by minimizing internal stress and maintaining the structural integrity of the sealing member.
Implementation Method 1
the sealing member having a side surface and a sealing surface, the side surface having a contact area contacting the inner wall of the case
Implementation Method 2
Different materials are used for the case and the sealing member in the above semiconductor device. Therefore, the case and sealing member have different linear expansion coefficients. When the semiconductor device is subjected to temperature changes, internal stress is generated accordingly.
Data Source
AI summary
A semiconductor device, including a semiconductor chip, a case having an opening formed therein and an inner wall communicating with the opening, and a sealing member. The inner wall surrounds a housing space for accommodating the semiconductor chip. The sealing member fills the housing space to seal the semiconductor chip. The sealing member has a side surface and a sealing surface. The side surface has a contact area contacting the inner wall of the case. The contact area is positioned, in a depth direction of the semiconductor device, closer to the semiconductor chip than is the sealing surface of the sealing member.