Copper Conductive Paste Composition for Low-Scatter Sintered Films
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conductive films formed using existing conductive pastes face challenges in achieving high conductivity due to scattering of copper particles during sintering, leading to poor conductivity and structural issues, especially when sufficient irradiation energy is applied to remove the binder resin.
Innovation Solution
A conductive paste composition with copper fine particles and coarse particles, a binder resin, and a dispersion medium, optimized with specific particle size ranges, ratios, and additives like polyvinylpyrrolidone and ethylene glycol, which reduces particle scattering and enhances sinterability, allowing for high conductivity without collapsing the film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sufficient irradiation energy is applied to remove the binder resin, then the conductivity is improved, but the copper particles scatter and the conductive film collapses
Solution Approach 1:
The patent applies preliminary action by pre-coating the copper fine particles with cuprous oxide and copper carbonate layers before forming the conductive paste. This preliminary coating creates a protective barrier that prevents copper particle scattering during subsequent sintering with high irradiation energy, while still allowing the binder resin to be sufficiently removed for achieving low conductivity.
Solution Approach 2:
The cuprous oxide and copper carbonate coatings on the copper fine particles serve as a cushioning layer that absorbs the mechanical stress and thermal shock during sintering. This beforehand cushioning prevents the copper particles from scattering and the conductive film from collapsing, even when sufficient irradiation energy is applied to remove the binder resin and achieve low conductivity.
2Strength
If the binder resin content is increased to improve adhesion, then the substrate adhesion is improved, but the sinterability of copper particles deteriorates
Solution Approach 1:
The patent optimizes the binder resin content to a specific range (0.1 to 2.0 parts by mass with respect to 100 parts by mass of copper fine particles and copper coarse particles). This parameter change ensures sufficient substrate adhesion while maintaining good sinterability of the copper particles, resolving the contradiction between adhesion and sinterability.
3Reliability
If copper fine particles with smaller size are used to improve conductivity, then the conductivity is improved, but the particle scattering during sintering increases
Solution Approach 1:
The copper fine particles are pre-coated with cuprous oxide and copper carbonate before being mixed with the binder resin and subjected to sintering. This preliminary coating action protects the small copper particles from scattering during sintering, enabling the use of fine particles (average particle diameter of 300 nm or less) to achieve low conductivity without the harmful scattering effect.
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 conductive paste achieves excellent conductivity with reduced particle scattering and improved sinterability, enabling the formation of conductive films with specific resistances below 10 μΩ·cm without additional processing steps, while maintaining substrate adhesion and reducing thermal load.
Implementation Method 1
heat treatment is performed to form a conductive film on the substrate
Implementation Method 2
sintering treatment with irradiation energy that is sufficient to remove the binder resin
Implementation Method 3
improve the sinterability of the copper particles by adjusting the sintering treatment conditions
Data Source
AI summary
An object of the present invention is to provide a conductive paste that can form a conductive film with excellent conductivity and that does not easily scatter copper fine particles even when sintered with irradiation energy that can sufficiently remove a binder resin, a conductive film-coated film using the conductive paste, and a method for producing a conductive film-coated substrate. The present invention provides a conductive paste containing copper fine particles with an average particle size of 300 nm or less, copper coarse particles with an average particle size of 3 to 11 μm, a binder resin, and a dispersion medium, wherein a content of the binder resin is 0.1 to 2.0 parts by mass with respect to a total of 100 parts by mass of the copper fine particles and the copper coarse particles; a conductive film-coated substrate including a substrate and a sintered body of the conductive paste provided on the substrate; and a method for producing a conductive film-coated substrate including providing a film containing the conductive paste a substrate; and applying a sintering treatment to the film.