Nickel Particle Composition for Pressureless Bonding
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Solution Overview
Problem
Current bonding materials for high-temperature applications in power semiconductor devices, particularly those using silicon carbide, require noble metals like silver for sufficient strength, but these are costly and inefficient, and existing nickel-based materials lack sufficient bonding strength without applying pressure.
Innovation Solution
A nickel particle composition with specific size ranges (30 nm to 200 nm fine particles and 0.5 μm to 20 μm coarse particles) and an organic binder, used in a reductive gas environment at 250° C. to 400° C., forms a strong bonding layer without the need for pressure, utilizing nickel particles with high nickel content and a controlled particle size distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If noble metals like silver are used in bonding materials for high-temperature applications, then bonding strength is improved, but cost increases and efficiency decreases
Solution Approach 1:
The patent replaces expensive noble metals (silver) with inexpensive base metals (nickel, copper, aluminum, or their alloys) as the metal particles in the bonding material. This substitution dramatically reduces material cost while maintaining bonding functionality through controlled particle size and sintering processes
Solution Approach 2:
The patent achieves high bonding strength with base metals by controlling critical parameters: metal particle size (0.1-10 μm), organic binder content (1-20 wt%), and sintering temperature (200-400°C). These parameter optimizations enable base metals to reach bonding performance comparable to noble metals without the associated cost
2Device complexity
If nickel-based bonding materials are used without pressure, then process complexity is reduced, but bonding strength is insufficient
Solution Approach 1:
The patent achieves pressureless bonding by optimizing the sintering temperature range (200-400°C) and metal particle size (0.1-10 μm). The fine particle size increases surface area and sintering activity, while the controlled temperature range enables sufficient diffusion bonding without requiring external pressure
Solution Approach 2:
The patent creates a composite bonding material system combining metal particles (nickel, copper, aluminum, or alloys) with organic binders. This composite structure allows the organic binder to provide initial cohesion and facilitate sintering, enabling the metal particles to achieve strong bonding through thermal processing alone without pressure
3Strength
If silver particles are used for bonding, then bonding strength is achieved, but the process requires pressure application which complicates equipment and increases cost
Solution Approach 1:
The patent replaces the mechanical pressure application system with a thermal processing system. Instead of using pressure to achieve bonding, the patent uses controlled sintering at 200-400°C to enable diffusion bonding of metal particles, eliminating the need for complex pressure application equipment
Solution Approach 2:
The patent changes the bonding mechanism from pressure-dependent to temperature-dependent by controlling sintering temperature (200-400°C) and particle size (0.1-10 μm). This parameter optimization enables thermal bonding without mechanical pressure, simplifying the equipment requirements
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 achieves high bonding strength comparable to silver-based materials without the use of noble metals, simplifying the bonding process and reducing costs by enabling bonding without pressure, thus enhancing the reliability and efficiency of high-temperature semiconductor device assembly.
Implementation Method 1
nickel fine particle having a size of 30 nm to 200 nm that readily undergoes inter-particle sintering by heating
Implementation Method 2
heating is performed at a temperature in the range of 250° C. to 400° C. in a reductive gas environment containing a reductive gas
Data Source
AI summary
A nickel particle composition is shown, including: A) a nickel particle having an average particle size in the range of 0.5 μm to 20 μm obtained via a laser diffraction/scattering method and containing 50 wt % or more of a nickel element; B) a nickel fine particle having an average primary particle size in the range of 30 nm to 200 nm observed via a scanning electron microscope and containing 50 wt % or more of a nickel element; and C) an organic binder in the range of 0.1 wt % to 2.5 wt % relative to the total metal content; and the weight ratio of a component A to a component B (component A:component B) is in the range of 30:70 to 70:30.