Power Semiconductor Module Wire Bonding Reliability
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Solution Overview
Problem
Power semiconductor modules, such as IGBT modules, face reliability issues due to interface peeling and aluminum wire breakage caused by thermal expansion mismatch between the aluminum wire and epoxy resin, leading to reduced lifespan.
Innovation Solution
Optimizing the wire diameter of the aluminum wire to 0.4±0.05 mmφ and the coefficient of linear expansion of the epoxy resin to 15-20 ppm/K, with a polyamide resin coating layer, and varying filler content to match thermal expansion coefficients, prevents interface peeling and enhances wire connection life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the aluminum wire diameter is increased to reduce thermal stress, then the wire connection reliability is improved, but the device complexity and manufacturing precision requirements increase
Solution Approach 1:
The patent optimizes the aluminum wire diameter to a specific range (0.3-0.5mm, preferably 0.4mm) to balance thermal stress resistance with manufacturing feasibility. This parameter optimization resolves the contradiction by finding the optimal value that provides sufficient mechanical strength without excessive complexity
Solution Approach 2:
The patent selects epoxy resin with a coefficient of linear expansion of 15-20ppm/K to match the aluminum wire's thermal expansion characteristics. This reduces thermal stress at the wire-resin interface during temperature cycling, thereby improving wire connection reliability without increasing device complexity
2Reliability
If the epoxy resin coefficient of linear expansion is reduced to match the aluminum wire, then the interface peeling is prevented, but the manufacturing precision of the resin formulation increases
Solution Approach 1:
The patent specifies a precise range for the epoxy resin's coefficient of linear expansion (15-20ppm/K) to match the aluminum wire's thermal expansion. This parameter control prevents interface peeling while maintaining manufacturability through clear specification ranges
Solution Approach 2:
The patent uses composite epoxy resin formulations incorporating specific fillers (such as silica or alumina) to achieve the target coefficient of linear expansion. The composite material approach allows precise control of thermal expansion properties while maintaining manufacturing feasibility
3Duration of action of stationary object
If the aluminum wire diameter is optimized to 0.4mm, then the connecting life-time is extended, but the manufacturing precision requirement for wire diameter control increases
Solution Approach 1:
The patent optimizes the aluminum wire diameter to 0.4mm with a tolerance of ±0.05mm. This specific parameter optimization extends connecting life-time by reducing thermal stress while maintaining reasonable manufacturing precision requirements through well-defined tolerance ranges
4Strength
If the sealing resin is changed from silicone gel to epoxy resin, then the stress dispersion of the solder layer is improved, but the thermal expansion mismatch with aluminum wire increases
Solution Approach 1:
The patent selects epoxy resin with a coefficient of linear expansion of 15-20ppm/K, which closely matches the aluminum wire's thermal expansion characteristics. This parameter selection maintains wire connection reliability while preserving the stress dispersion benefits of using a hard resin instead of silicone gel
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 extends the power cycle life-time of the module by reducing thermal stress and preventing wire neck cutting and Si chip cracking, ensuring higher reliability and longer module lifespan.
Implementation Method 1
This aluminum wire is bonded to an aluminum electrode at the surface of the power semiconductor chip by ultrasonic bonding
Implementation Method 2
a power semiconductor chip and an aluminum wire at the vicinity of a bonding part repeat stretching and shrinking movement according to each coefficient of linear expansion
Data Source
AI summary
A power semiconductor module having a surface of the power semiconductor chip and an external circuit pattern connected by an aluminum wire, and sealed with an epoxy resin, wherein wire diameter of the aluminum wire is 0.4±0.05 mmφ, and coefficient of linear expansion of the epoxy resin in a rated temperature range of a module is from 15 to 20 ppm/K.