Power Semiconductor Module Resin Structure for Bond Wire Crack Resistance
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Solution Overview
Problem
The existing power semiconductor devices face reliability issues due to stress caused by the difference in thermal expansion coefficients between semiconductor devices and metal wires, leading to cracking in the bonding section, which is not effectively prevented by the insulating resin used in current designs.
Innovation Solution
A power semiconductor module is designed with a specific configuration that includes a semiconductor device, conductive wires, and multiple resin members, where the first resin member has higher break elongation and strength, and the second resin member has higher tensile elastic modulus, ensuring that the conductive wire remains fixed to the semiconductor device without breaking even under thermal cycles, and the third resin member seals the components to prevent peeling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single insulating resin is used to cover the bonding section, then the structure is simple, but cracks occur in the bonding section due to thermal expansion stress
Solution Approach 1:
The insulating resin is divided into two distinct layers: a first insulating resin layer directly covering the bonding section with high break elongation and high break strength to prevent crack propagation, and a second insulating resin layer covering the first layer with high tensile elastic modulus to provide structural support. This segmentation allows each layer to perform its specific function optimally, preventing cracks while maintaining a manageable structure.
Solution Approach 2:
The patent employs a composite resin structure where two different insulating resins with complementary properties are combined. The first resin provides crack resistance through high break elongation and strength, while the second resin provides dimensional stability through high tensile elastic modulus. This composite approach creates a synergistic effect that neither single resin could achieve alone, effectively preventing cracks under thermal expansion stress.
2Reliability
If the insulating resin has high break strength to prevent cracks, then bonding section reliability improves, but the resin may be too rigid to accommodate thermal expansion differences
Solution Approach 1:
The resin system is segmented into two functional layers: the first insulating resin layer with high break elongation and high break strength that provides crack resistance and flexibility to accommodate thermal expansion, and the second insulating resin layer with high tensile elastic modulus that provides structural stability. This segmentation resolves the contradiction by assigning different mechanical properties to different layers.
Solution Approach 2:
Different regions of the resin structure are assigned different qualities: the first resin layer directly at the bonding section has high break elongation and strength to locally accommodate thermal stress and prevent cracks, while the second resin layer provides overall structural support. This local quality differentiation allows the system to simultaneously achieve flexibility where needed and rigidity where beneficial.
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 significantly enhances the reliability of the power semiconductor module by preventing cracks in the bonding section and maintaining the connection between the semiconductor device and conductive wire during heat cycles, thereby improving the module's overall performance.
Implementation Method 1
The first break elongation of the first resin member is greater than the second break elongation of the second resin member. The first break strength of the first resin member is greater than the second break strength of the second resin member. The second tensile elastic modulus of the second resin member is greater than the first tensile elastic modulus of the first resin member.
Implementation Method 2
Due to the difference between the coefficient of thermal expansion of the semiconductor device and the coefficient of thermal expansion of the metal wire, a stress is repeatedly applied to the bonding section between the semiconductor device and the metal wire when the power semiconductor device is being used.
Data Source
AI summary
The conductive wire is bonded to the front electrode of the semiconductor device at the bonding section. The first resin member covers at least one end portion of two end portions of the bonding section, the first surface of the front electrode, and the second surface of the conductive wire. The second resin member covers the bent portion of the first resin member. The first resin member has a higher break elongation and a higher break strength than the second resin member. The second tensile elastic modulus of the second resin member is greater than the first tensile elastic modulus of the first resin member. Thereby, the reliability of the power semiconductor module is improved.