Sintered Joint Formation for High-Temperature Power Modules
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Solution Overview
Problem
Power electronic modules face reliability issues due to the low melting point of solder joints, which fail under high temperatures, and there is a need for high-temperature modules capable of operating above 200°C without using noble metal surfaces to reduce costs.
Innovation Solution
A method involving a paste of metal grains, solvents, and sintering inhibitors is used to form sintered joints between semiconductor chips and substrates or baseplates, eliminating the need for noble metal layers by decomposing inhibitors under controlled temperature and force to create strong bonds suitable for high-temperature applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If soft soldering with Sn-Pb, Sn-Ag, or Sn-Ag-Cu alloy is used for joining semiconductor chips to substrates, then ease of manufacture is improved, but reliability deteriorates at high temperatures above 150°C due to crack formation
Solution Approach 1:
The patent changes the fundamental parameter of the joining process from low-temperature soft soldering to high-temperature sintering. By applying a metal paste containing sintering inhibitors and subjecting it to controlled heating and pressure, the paste transforms into a sintered joint capable of withstanding temperatures above 150°C, thereby resolving the reliability issue while maintaining manufacturing feasibility
Solution Approach 2:
The patent replaces the mechanical soft soldering process with a thermal-chemical sintering process. Instead of relying on molten solder to form joints, the invention uses heat and pressure to sinter metal particles in the paste directly onto the substrate, creating a more thermally stable connection that eliminates crack formation at high temperatures
2Reliability
If noble metal surfaces are used for joining semiconductor chips to substrates and substrates to metal baseplates, then reliability is improved, but cost increases
Solution Approach 1:
The patent replaces expensive noble metal surfaces with a cost-effective metal paste formulation. The paste contains metal grains, solvents, and sintering inhibitors that can be applied as a thin layer and sintered in place, providing reliable high-temperature performance without the need for costly noble metal plating on substrates and baseplates
Solution Approach 2:
The invention creates a composite joining material by formulating a metal paste that combines metal grains with sintering inhibitors. This composite paste, when sintered, forms a joint that achieves the reliability of noble metal connections while using base metals, thereby reducing material costs while maintaining high-temperature performance
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 enables the creation of high-temperature power electronic modules that can operate up to and exceeding 200°C with improved reliability and reduced costs by forming sintered joints without noble metal layers, enhancing thermal cycling reliability and maintaining module functionality.
Implementation Method 1
evaporating the solvent in the paste
Implementation Method 2
decomposing the sintering inhibitors to form a sintered joint joining the die to the metal layer
Implementation Method 3
decomposing the sintering inhibitors
Data Source
AI summary
A method comprises applying a paste comprising metal grains, a solvent, and a sintering inhibitor to one of a die and a metal layer. The method comprises evaporating the solvent in the paste and placing the one of the die and the metal layer on the other of the die and the metal layer such that the paste contacts the die and the metal layer. The method comprises applying a force to the one of the die and the metal layer and decomposing the sintering inhibitors to form a sintered joint joining the die to the metal layer.