Silver Sinter Paste Composition to Reduce Squeeze-Out
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Solution Overview
Problem
Existing silver sintering pastes exhibit undesirable squeeze-out behavior during the sintering process, particularly when the layer thickness is high or the contact surfaces of components are large, leading to an unstable connection.
Innovation Solution
A silver sintering paste composition comprising 5-40% silver flakes with specific particle size ranges and 50-85% silver particles, along with organic solvents and cellulose derivatives, is developed to minimize squeeze-out and enhance connection stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a large amount of metal sintering paste is used between components with large contact areas, then the connection strength is improved, but squeeze-out behavior increases
Solution Approach 1:
The invention changes the particle size parameters of the sintering paste, specifically using silver particles with D90 between 300-1000 nm and silver flakes with D90 between 5-20 μm. This parameter optimization allows the paste to maintain adequate connection strength while significantly reducing squeeze-out behavior during pressure sintering of components with large contact areas (>100 mm²).
Solution Approach 2:
The invention uses a composite material system combining two distinct silver forms: spherical silver particles (50-85 wt.%) and flake-shaped silver flakes (5-40 wt.%). This composite structure leverages the flowability of spherical particles to reduce squeeze-out while maintaining connection strength through the combined sintering behavior of both particle types.
2Stability of the object's composition
If the layer thickness of metal sintering paste is increased, then the connection stability is improved, but squeeze-out behavior is exacerbated
Solution Approach 1:
The invention optimizes the particle size parameters, specifically using silver particles with D90 between 300-1000 nm and silver flakes with D90 between 5-20 μm. This parameter optimization enables the paste to achieve adequate connection stability with reduced layer thickness while minimizing squeeze-out behavior during pressure sintering.
Solution Approach 2:
The invention creates local quality differences within the paste layer through the bimodal particle distribution. The spherical particles (300-1000 nm D90) provide local flowability and stress distribution to prevent squeeze-out, while the flake particles (5-20 μm D90) contribute to structural integrity and connection stability, allowing thin layers to perform optimally.
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 optimized paste composition significantly reduces squeeze-out behavior and achieves a strong, electrically and thermally conductive connection between components, maintaining stability even under pressure sintering conditions.
Implementation Method 1
Sintering the joining of electronic components is a common process... a sintering joining material, such as sintering paste, is applied between them. The sandwich configuration created using sintering paste is then subjected to a drying and sintering step, during which a mechanically strong, electrically and thermally conductive bond between the components is formed.
Implementation Method 2
The sandwich configuration created using sintering paste is then subjected to a drying and sintering step...
Data Source
AI summary
Silver sintering paste consisting of: (A) 5 to 40 wt.% silver flakes with a particle size D90 in the range of 5 to 20 µm, (B) 50 to 85 wt.% silver particles with a particle size D90 in the range of 300 to 1000 nm, (C) 10 to 25 wt.% at least one organic solvent, (D) 0 to 2 wt.% at least one cellulose derivative, and (E) 0 to 10 wt.% at least one additive different from components (A) to (D).