Reducing-Agent Coated Sintered Compound for Low-Temperature Joining
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Solution Overview
Problem
Power electronics in high-temperature applications face challenges with existing solder joints, particularly lead-containing solders which are environmentally restricted, and lead-free hard solders that require high melting points, limiting the selection of suitable joining partners for sintered connections.
Innovation Solution
A starting material for sintered connections comprising particles with a metal compound or noble metal oxide coated with a reducing agent, allowing for reduction to elemental metal at low temperatures, ensuring a homogeneous sintered structure with high thermal and electrical conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If lead-free hard solders are used for high-temperature applications above 200°C, then the melting point and high-temperature suitability are improved, but the processing temperature becomes excessively high which limits the choice of joining partners
Solution Approach 1:
The patent changes the chemical composition parameters of the sintered compound by incorporating specific metal powders (silver, copper, nickel, palladium, platinum) in controlled ratios, along with oxide materials and organic binders. This composition optimization enables the sintered compound to achieve both high-temperature stability and lower processing temperatures compared to traditional hard solders, thereby expanding the range of compatible joining partners.
2Ease of manufacture
If traditional soldering processes are used, then the joining process is simple, but the processing temperature is too high which damages temperature-sensitive components
Solution Approach 1:
The patent replaces the traditional melting-based soldering process with a sintering process that occurs at lower temperatures. The sintered compound is applied as a paste containing metal powders and organic binders, which are then sintered at temperatures below the melting point of conventional solders. This substitution of the joining mechanism allows for simpler processing without exposing temperature-sensitive components to excessive heat.
3Ease of manufacture
If lead-containing solder joints are used, then the ease of joining is improved, but environmental compliance deteriorates due to legal restrictions
Solution Approach 1:
The patent employs a paste-based sintered compound that can be applied and processed in a single step, replacing the need for traditional multi-step soldering processes. The organic binders in the paste decompose during sintering, leaving behind a dense sintered structure. This approach eliminates lead while maintaining ease of joining through a simplified process, ensuring environmental compliance without sacrificing manufacturing simplicity.
4Object-affected harmful factors
If sintered connections are produced at low temperatures, then the protection of temperature-sensitive components is improved, but the conversion rate of metal compounds to elemental metals deteriorates
Solution Approach 1:
The patent optimizes the chemical composition of the sintered compound by selecting specific metal powders and oxide materials with appropriate reactivity characteristics. The organic binders are chosen to decompose at controlled rates during sintering, providing reducing atmosphere that facilitates the conversion of metal oxides to elemental metals even at lower temperatures. This parameter optimization ensures high conversion rates while maintaining low processing temperatures that protect temperature-sensitive components.
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
The solution enables the formation of sintered connections with high thermal and electrical conductivity, suitable for high-temperature applications, while maintaining chemical stability and reducing processing temperatures, thus addressing the limitations of existing solder joints.
Implementation Method 1
the organic metal compound and/or the noble metal oxide being converted into the underlying elemental metal and/or noble metal during a temperature treatment of the starting material
Implementation Method 2
the coating contains a reducing agent, by means of which the reduction of the organic metal compound and / or the noble metal oxide to the elemental metal and / or noble metal at a temperature below the sintering temperature takes place
Implementation Method 3
together with the silver flakes and the nanosilver, form the sintered compound
Data Source
Figure 1a~1b
Figure 2a~2c
Figure 3
AI summary
The starting material of a sintered compound according to the invention comprises particles that contain at least a proportion of an organic metal compound and/or a noble metal oxide, wherein the organic metal compound and/or the noble metal oxide is converted into the elemental metal and/or noble metal during a heat treatment of the starting material. A characteristic feature of the invention is that the particles have a coating containing a reducing agent, by means of which the reduction of the organic metal compound and/or the noble metal oxide to the elemental metal and/or noble metal takes place at a temperature below the sintering temperature of the elemental metal and/or noble metal.