Flip-Chip Power Module Clip Structure for Wire-Bond-Free Cooling
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Solution Overview
Problem
High-power semiconductor devices used in electric vehicles and industrial applications face reliability issues due to mechanical stress and thermal management challenges, including die cracking and wire bond vulnerability, which affect yield and reliability, especially at high temperatures and currents.
Innovation Solution
The implementation of a power module design featuring a pre-molded clip assembly with integrated metallization and oversized clips that cover the entire semiconductor die, providing mechanical support and heat dissipation, and using a flip-chip configuration with metallization embedded in the DBM structure to eliminate wire bonds and enhance thermal performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wire bonds are used for electrical interconnections, then electrical connectivity is achieved, but mechanical stress and reliability issues occur due to wire bond vulnerability
Solution Approach 1:
The patent removes wire bonds from the system entirely and replaces them with a direct metal clip-to-die attachment structure. The clip assembly with integrated metallization provides electrical interconnection without vulnerable wire bonds, extracting the harmful element from the system.
Solution Approach 2:
The patent replaces the mechanical wire bond system with a rigid metal clip assembly that uses sintered silver and solder layers for attachment. This substitution eliminates the mechanical stress concentration points inherent in wire bonds while providing robust electrical and mechanical connections.
2Temperature
If conventional cooling structures are used, then thermal management is provided, but thermal resistance remains high affecting device performance
Solution Approach 1:
The patent merges the electrical interconnection function with the thermal management function by integrating metallization directly into the metal clip assembly. The same clip that provides electrical connectivity also serves as a heat dissipation pathway, reducing overall thermal resistance by up to 10%.
Solution Approach 2:
The clip assembly uses composite construction with sintered silver layer, solder layer, and metal clip materials to optimize both electrical conductivity and thermal conductivity. This composite structure enables efficient heat transfer from the die to the cooling system while maintaining low electrical resistance.
3Strength
If mechanical support structures are added to reduce stress, then die cracking is prevented, but device complexity increases
Solution Approach 1:
The metal clip assembly performs multiple functions simultaneously: it provides electrical interconnection, mechanical support to prevent die cracking, and thermal management. This multi-functionality eliminates the need for separate stress-relief structures, reducing overall device complexity while maintaining die strength.
Solution Approach 2:
The clip assembly is segmented into distinct functional layers (sintered silver layer, solder layer, metal clip) that can be optimized independently for their respective functions while working together as an integrated unit. This segmentation allows for targeted optimization without increasing overall complexity.
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 reduces thermal resistance by up to 10% and enhances reliability by distributing mechanical forces and improving heat dissipation, while eliminating the need for wire bonds, thus addressing the challenges of die cracking and thermal management in high-power modules.
Implementation Method 1
The semiconductor die is attached to both the DBM structure and the clip by respective layers of sintered silver
Implementation Method 2
The semiconductor die is attached to both the DBM structure and the clip by respective layers of sintered silver
Implementation Method 3
The semiconductor die is attached to the DBM structure by a layer of sintered silver and to the clip by a layer of a lead-based solder
Implementation Method 4
The semiconductor die is attached to the DBM structure by a layer of sintered silver and to the clip by a layer of a lead-based solder
Implementation Method 5
a direct bonded metal (DBM) structure coupled to a first side of the semiconductor die, the DBM structure providing single-sided cooling
Data Source
AI summary
Devices and methods are disclosed for high power inverter modules with enhanced thermal and mechanical performance, for use in electric vehicles. The disclosed devices feature enlarged clips that cover an entire die, to distribute mechanical forces, thus preventing die cracks for improved reliability. In these power modules, semiconductor dies are sandwiched between a three-layer direct bond metal (DBM) structure and the enlarged clip. A pre-molded clip assembly can be used that includes integrated metalliization to eliminate the need for external wire bonds. Alternatively, semiconductor dies can be inverted in a flip-chip configuration to face a modified DBM structure that integrates the metallization. Simulations of the disclosed power inverters indicate improved efficiency in dissipating heat.