Metallic Particle Preforms for Faster, Uniform Brazed Sintering
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Solution Overview
Problem
Current sintering processes for electronic components face challenges with high viscosity braze pastes and suspensions, leading to uneven application, decanting issues, and suboptimal adherence due to agglomeration and oxidation of metallic particles during desolvation on the substrate, which prolongs the process and increases the risk of loss of consistency.
Innovation Solution
A pretreatment process involving desolvation and compaction of metallic particle suspensions or pastes to create a preform with controlled shape, thickness, and density, using filtration, vacuum desolvation, and compacting techniques to produce a preform of metallic particles for improved sintering on substrates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If desolvation is performed on the substrate after paste application, then the sintering process can proceed, but the process time increases and adherence becomes suboptimal due to agglomeration
Solution Approach 1:
The patent applies preliminary action by performing desolvation and compacting operations on the paste before it is applied to the substrate. The paste is desolvated to remove solvents and binders, then compacted into a preform with controlled density and shape. This preformed state is then applied to the substrate, eliminating the need for post-application desolvation and preventing agglomeration during the process.
2Stability of the object's composition
If high viscosity paste is used for brazing, then metallic particles are well-bound, but application becomes difficult and decanting problems occur
Solution Approach 1:
The patent segments the brazing process into distinct stages: paste preparation with controlled viscosity for easy application, desolvation to remove solvents and binders, compacting to achieve desired density, and final sintering. This segmentation allows each stage to be optimized independently - the paste can be formulated for easy application, then transformed into a compact preform that maintains stability without requiring high viscosity throughout the entire process.
Solution Approach 2:
The patent applies parameter changes by systematically modifying the physical and chemical properties of the paste through controlled desolvation and compacting. The solvent content is reduced, binder content is adjusted, and density is increased through compaction. These parameter transformations convert the paste from a high-viscosity, hard-to-apply state to a stable, compact preform that is easy to handle and apply to the substrate.
3Ease of operation
If suspension is used instead of paste, then application is easier, but decanting problems and nozzle blocking occur
Solution Approach 1:
The patent applies preliminary action by converting the suspension into a compacted preform before application. The suspension undergoes desolvation to remove excess liquid, followed by compacting to achieve controlled density and eliminate the fluid characteristics that cause decanting and nozzle blocking. The resulting solid preform maintains the ease of placement associated with suspensions while eliminating their reliability problems.
4Device complexity
If paste is applied directly to substrate, then process is simple, but adherence is suboptimal due to agglomeration during desolvation
Solution Approach 1:
The patent applies preliminary action by performing desolvation and compacting operations before substrate application. The paste is desolvated to remove solvents and binders, then compacted into a dense preform with controlled porosity. This preformed state ensures uniform particle distribution and prevents agglomeration when applied to the substrate, significantly improving adherence quality.
Solution Approach 2:
The patent employs pneumatic techniques during the compacting stage to achieve controlled density and uniform particle distribution in the preform. Gas pressure or vacuum techniques are used to compact the desolvated paste material, ensuring consistent density and eliminating voids that would lead to agglomeration and poor adherence during subsequent sintering.
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 method reduces cycle times, ensures precise control over brazing height and alignment, and produces preforms with high mechanical strength and minimal non-metallic compounds, enhancing the efficiency and reliability of the sintering process.
Implementation Method 1
the suspension of metallic or metallic oxalate grains is subjected to a prior filtration step to filter it through a membrane filter arranged over a suction device
Implementation Method 2
the desolvation step may be performed in a vacuum and at a temperature of between 60° C. and 100° C.
Implementation Method 3
the desolvation step may be performed in a vacuum
Implementation Method 4
a compacting step of the desolvated brazing composition such as to obtain a preform of metallic particles or metallic oxalate
Data Source
AI summary
The invention relates to a pretreatment process for a brazing composition that comprises metallic particles with a granulometry in the order of the micrometer or nanometer, one or several binders and one or several solvents, said process comprising:a desolvation step of the brazing composition, so as to obtain a desolvated brazing composition,then a compacting step of the desolvated brazing composition so as to obtain a preform of metallic particles, said preform being able to be used for the sintering of an electronic, photonic, thermal or mechanical component onto a substrate,the brazing composition being represented either by a brazing paste, or by a suspension of metallic or metallic oxalate grains in suspension in a solvent.