Stress-Relaxation Adhesive Layer for Semiconductor Device Thermal Management
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Solution Overview
Problem
Wide band gap semiconductor devices, such as those using SiC and GaN, face reliability issues due to crack formation and separation of the sealing resin member from the substrate during high-temperature heat cycles, leading to reduced device reliability.
Innovation Solution
A semiconductor device configuration featuring a stress-relaxation adhesive layer with a lower modulus of elasticity than the sealing resin, covering exposed portions of the insulating substrate, helps to relax thermal stress and prevent crack formation and separation, ensuring stable operation at high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a semiconductor device operates at high temperatures, then the performance and functionality of wide band gap semiconductor elements are improved, but crack formation and separation of the sealing resin member occur, reducing reliability
Solution Approach 1:
The patent introduces a stress-relaxation adhesive layer with specifically controlled physical properties (modulus of elasticity between 0.01 GPa and 1 GPa, thickness ratio of 0.05 to 0.5) to change the mechanical parameters of the sealing structure, enabling it to accommodate thermal stress at high temperatures without cracking or separating
Solution Approach 2:
The patent creates a composite sealing structure consisting of multiple materials with different mechanical properties: the sealing resin member, the stress-relaxation adhesive layer with intermediate modulus, and the insulating substrate. This composite structure distributes and manages thermal stress across layers with graded mechanical properties, preventing failure at interfaces
2Strength
If the modulus of elasticity of the sealing resin is increased to improve structural strength, then crack resistance is improved, but stress relaxation capability during heat cycles deteriorates
Solution Approach 1:
The patent optimizes the modulus of elasticity parameter of the stress-relaxation adhesive layer to be within 0.01 GPa to 1 GPa, which is lower than the sealing resin but higher than the insulating substrate, creating a gradient that balances strength and stress relaxation capabilities across the sealing structure
Solution Approach 2:
The stress-relaxation adhesive layer acts as an intermediary between the rigid sealing resin member and the insulating substrate, providing a transition zone with intermediate mechanical properties that facilitates stress distribution and prevents concentration at the interface between dissimilar materials
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 configuration significantly enhances the reliability of semiconductor devices by preventing crack formation and separation of the sealing resin member from the substrate during heat cycles, maintaining device functionality at elevated temperatures.
Implementation Method 1
a stress-relaxation adhesive layer made of resin that covers at least a part of the portion of the surface of the insulating substrate where the electrode pattern and back-surface electrode are not formed
Implementation Method 2
when the semiconductor device operates at high temperatures, the stress which is generated on a sealing resin member is relaxed by a stress-relaxation adhesive layer
Data Source
AI summary
A semiconductor device includes a semiconductor element substrate, wherein an electrode pattern is formed on one surface of an insulating substrate and a back-surface electrode is formed on the other surface of the insulating substrate; a stress-relaxation adhesive layer made of resin that covers at least a part of a portion of the surface of the insulating substrate where the electrode pattern and the back-surface electrode are not formed; and a semiconductor element affixed, using a bonding material, to the surface of the electrode pattern opposite the insulating substrate, and a first sealing resin member which covers the semiconductor element and the semiconductor element substrate, and a modulus of elasticity of the stress-relaxation adhesive layer is lower than that of the first sealing resin member.