Semiconductor Module External Contact Wing Design for Crack Reduction
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Solution Overview
Problem
Semiconductor modules face issues with crack formation and delamination due to thermal expansion coefficient differences between the encapsulation body and external contacts, leading to potential electrical insulation and mechanical protection failures.
Innovation Solution
The semiconductor module design incorporates external contacts with wings and cutouts filled with encapsulation material, which reduces mechanical stress by replacing metal or alloy with encapsulation material in high-stress areas, and can have bent wings out of the plane to further mitigate stress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external contacts are made of metal or alloy with different thermal expansion coefficients than the encapsulation body, then electrical conductivity and mechanical strength are improved, but crack formation and delamination occur due to thermal expansion differences
Solution Approach 1:
The external contact has a non-uniform structure with a wing portion that has a smaller cross-sectional area than the main body. This local variation in geometry allows different regions of the external contact to have different mechanical properties, with the narrower wing portion experiencing reduced stress during thermal expansion cycles, thereby preventing crack formation while maintaining overall electrical conductivity and strength.
Solution Approach 2:
Instead of making the entire external contact uniform in cross-section, the invention inverts the conventional design by introducing a wing portion with reduced cross-sectional area. This inverted geometry concentrates the thermal expansion stress in a controlled manner at the wing-root interface, preventing uncontrolled crack propagation along the encapsulation body interface.
2Ease of manufacture
If the external contact has a uniform cross-sectional shape, then manufacturing is simplified, but stress concentration occurs at the interface with the encapsulation body during thermal cycling
Solution Approach 1:
The external contact features a wing portion with a locally reduced cross-sectional area compared to the main body. This local geometric modification creates a stress-relief zone that prevents stress concentration at the encapsulation body interface during thermal cycling, while the rest of the structure maintains its simple uniform geometry for ease of manufacturing.
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 formation of cracks and delamination, enhancing the reliability of semiconductor modules by minimizing thermal expansion-related mechanical stresses and maintaining electrical insulation.
Implementation Method 1
The dielectric material of the encapsulation bodies on one side and the metal or alloy of the external contacts or other electrically conductive components on the other side have thermal expansion coefficients which are significantly different. This can lead to the formation of cracks in the encapsulation body or the partial detachment of the encapsulation body from the external contacts (delamination) due to temperature changes
Data Source
AI summary
A semiconductor module includes: a chip carrier having a first side and a second, opposite side; a semiconductor chip arranged on the first side of the chip carrier; an encapsulation body that encapsulates the semiconductor chip; and at least two external contacts made of a metal or an alloy and arranged next to each other, which are electrically and mechanically connected to the first side of the first chip carrier and protrude laterally out of the encapsulation body. At least one of the external contacts has at least one wing arranged within the encapsulation body and located opposite the other external contact. The wing includes one or more cutouts that are filled with the encapsulation material of the encapsulation body.