Metal Paste Low-Temperature Sintering via Particle Size and Additive Control
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Solution Overview
Problem
Metal pastes with silver particles in the nano-level face challenges in achieving favorable printability and low resistance values when sintered at temperatures of 150° C. or lower, which is essential for forming fine circuit patterns and conductive bonding materials.
Innovation Solution
A metal paste is formulated with silver particles of 100 to 200 nm size, bound with an amine compound as a protective agent and containing high-molecular-weight ethyl cellulose as an additive, which improves printability and maintains low resistance values by ensuring moderate particle size distribution and appropriate molecular weight ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If silver particles in nano-level (several nm to several tens of nm) are used to achieve low-temperature sintering, then sintering temperature can be reduced to 200°C or lower, but the resistance value of the sintered body becomes remarkably higher
Solution Approach 1:
The patent changes the particle size parameter from ultra-fine (several nm to tens of nm) to moderate fine (100 to 200 nm). This parameter optimization maintains the low-temperature sintering capability (150°C or lower) while significantly reducing the resistance value of the sintered body, achieving both low temperature processing and low resistance
Solution Approach 2:
The patent creates a composite structure by combining silver particles of specific size (100-200 nm) with a controlled particle size distribution (average 60-800 nm). This composite approach allows the fine particles to enable low-temperature sintering while larger particles in the distribution maintain low resistance in the sintered body
2Temperature
If silver particles with particle size of 100 to 200 nm are used, then low-temperature sintering (150°C or lower) is achieved, but printability may be compromised
Solution Approach 1:
The patent optimizes multiple parameters simultaneously: particle size (100-200 nm for fine particles, average 60-800 nm), particle size distribution, and protective agent type (amine compound). This multi-parameter optimization ensures both low-temperature sintering capability and favorable printability are achieved
Solution Approach 2:
The patent introduces an amine compound as a protective agent that acts as an intermediary between the silver particles and the printing process. This protective agent coating on the particle surfaces improves printability by preventing particle aggregation and ensuring uniform deposition, while not interfering with the low-temperature sintering process
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 metal paste achieves favorable printability and sintering at low temperatures, producing a sintered body with low resistance values, making it suitable for conductive bonding and thermal conductivity applications.
Implementation Method 1
the silver particles are bound with an amine compound having 4 to 8 carbon atoms in total as a protective agent
Implementation Method 2
heated and calcined to sinter the metal particles
Implementation Method 3
the metal paste contains as an additive a high-molecular-weight ethyl cellulose having a number average molecular weight of 40000 to 90000
Data Source
AI summary
A metal paste formed by kneading a solid content including silver particles and a solvent, in which the solid content includes silver particles containing silver particles having a particle size of 100 to 200 nm by 30% or more based on the number of particles, the silver particles have an average particle size of 60 to 800 nm as a whole, the silver particles constituting the solid content are bound with an amine compound having 4 to 8 carbon atoms in total as a protective agent, and the metal paste contains as an additive a high-molecular-weight ethyl cellulose having a number average molecular weight of 40000 to 90000. Since the metal paste contains a high-molecular-weight ethyl cellulose, a sintered body having a low resistance can be maintained while printability is improved. The metal paste has favorable printability, and can form a sintered body having a low resistance even in a low temperature region of 150° C. or lower.