Thick-Wire Copper Bonding with Metallic Moulded Bodies
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Solution Overview
Problem
The existing bonding technologies for power semiconductor chips, particularly on the upper side, face limitations in life duration and are prone to mechanical stress and fracture due to their thinness, which complicates handling and testing processes.
Innovation Solution
Implementing a thick-wire copper bonding technology with metallic moulded bodies above and below the semiconductor, using low-temperature sintering or diffusion soldering to create a stable and symmetric thermo-mechanical environment, protecting the semiconductor surfaces and enabling safe electrical testing before final bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the semiconductor thickness is reduced to decrease electrical losses, then electrical efficiency is improved, but mechanical strength and fracture resistance deteriorate
Solution Approach 1:
The patent introduces metallic moulded bodies as separate structural elements that are integrated with the semiconductor chip. These moulded bodies act as independent load-bearing components that compensate for the reduced mechanical strength of thin semiconductors, allowing the semiconductor itself to be made thinner for electrical efficiency without compromising overall mechanical integrity.
Solution Approach 2:
The patent creates a composite structure combining the semiconductor chip with metallic moulded bodies. This composite construction integrates materials with different properties - the semiconductor provides electrical functionality while the metallic moulded bodies provide mechanical strength and fracture resistance, enabling thin semiconductor design without sacrificing structural integrity.
2Reliability
If Al-bonding technology is used on the upper side, then bonding process is established and reliable, but life duration is limited due to physical stress limits
Solution Approach 1:
The patent transitions from aluminium bonding to copper bonding, changing the material parameter of the bonding technology. Copper bonding provides superior mechanical strength, higher thermal conductivity, and greater ductility compared to aluminium bonding, enabling the connection to withstand higher mechanical stresses and thermal cycles, thus extending the life duration while maintaining bonding reliability.
3Loss of energy
If the semiconductor is made thinner to reduce electrical losses, then electrical efficiency is improved, but handling difficulty and fracture risk increase
Solution Approach 1:
The patent divides the mechanical load-bearing function from the electrical conduction function. The metallic moulded bodies assume the mechanical load and provide structural support during handling, while the thin semiconductor chip focuses on electrical conduction. This segmentation allows the semiconductor to be thin for electrical efficiency while the moulded bodies ensure handling ease.
Solution Approach 2:
The metallic moulded bodies are integrated with the semiconductor chip beforehand to provide mechanical protection and structural support. This prior reinforcement cushions the thin semiconductor against mechanical stresses during handling and processing, preventing fracture while allowing the semiconductor to maintain its thin profile for electrical efficiency.
4Duration of action of stationary object
If sintered connection is used on the lower side, then life duration is increased, but thermal and electrical requirements on upper and lower connections become more demanding
Solution Approach 1:
The patent changes the bonding material parameter from aluminium to copper on the upper side. Copper's superior thermal conductivity (approximately twice that of aluminium) and higher electrical conductivity allow the connection to meet the increased thermal and electrical requirements imposed by the sintered connection on the lower side, enabling the system to achieve extended life duration through sintering while effectively managing thermal and electrical loads.
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 approach significantly enhances the load cycle endurance and reduces the risk of fractures, ensuring stable and efficient electrical connections while protecting the semiconductor surfaces during bonding and testing processes.
Implementation Method 1
creating a cohesive, electrically conductive connection with the upper side potential faces of a power semiconductor chip by means of a bonding layer in a low-temperature sintering or diffusion soldering process
Implementation Method 2
creating a cohesive, electrically conductive connection with the upper side potential faces of a power semiconductor chip by means of a bonding layer in a low-temperature sintering or diffusion soldering process
Data Source
AI summary
The invention relates to a method for connecting a power semi-conductor chip having upper-sided potential surfaces to thick wires or strips, consisting of the following steps: Providing a metal molded body corresponding to the shape of the upper-sided potential surfaces, applying a connecting layer to the upper-sided potential surfaces or to the metal molded bodies, and applying the metal molded bodies and adding a material fit, electrically conductive compound to the potential surfaces prior to the joining of the thick wire bonds to the non-added upper side of the molded body.