Silver Conductive Paste Sintering for Low Resistance Wiring
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Solution Overview
Problem
Conventional methods for producing conductive materials, such as those used in electronic devices and light-emitting devices, face challenges including high electric resistance, material instability, and the generation of gases during high-temperature reactions, which can lead to voids and reduced reliability.
Innovation Solution
A method involving the sintering of silver particles with a median diameter of 0.1 μm to 15 μm in the presence of a metal oxide or oxygen at temperatures between 150°C to 320°C, which allows for the formation of a conductive material without the need for adhesives and reduces gas generation, resulting in a material with low electric resistance and improved stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a paste-form conductive composition containing metal particles and adhesive is heated to form wiring, then wiring is produced without etching, but the electric resistance obtained is about 5×10−5 Ωcm which is relatively high
Solution Approach 1:
The invention changes the particle size parameter of silver particles from micron order to sub-micron order (0.1-15 μm), and controls the heating temperature parameter (150-320°C) to achieve sintering that reduces electric resistance to 5×10−6 Ωcm or lower, resolving the contradiction between manufacturability and electrical performance
Solution Approach 2:
The invention uses a composite material system consisting of sub-micron silver particles combined with metal oxide particles (such as copper oxide, zinc oxide, or bismuth oxide) that act as sintering aids, creating a composite conductive material that achieves low resistance through enhanced particle bonding without requiring traditional adhesives
2Reliability
If microparticles of silver compound such as silver oxide are reduced by heating with reducing organic solvent, then silver particles are connected to form wiring, but intense reaction generates large amount of gas causing irregular voids that become stress concentration points
Solution Approach 1:
The invention extracts and eliminates the reducing organic solvent from the composition, replacing it with an oxidative heating process in atmosphere containing oxygen or ozone. This removes the source of intense gas-generating reactions while still achieving silver particle connection through controlled oxidation and sintering
Solution Approach 2:
The invention uses a controlled atmospheric environment (oxygen or ozone atmosphere) during heating that prevents uncontrolled reduction reactions. The atmosphere is carefully selected to enable controlled oxidation of metal oxide particles and sintering of silver particles without generating excessive gas that would create voids
3Loss of substance
If conventional etching method is used to produce copper wiring, then wiring is produced on substrate, but large amount of liquids and materials are wasted
Solution Approach 1:
The invention replaces the chemical etching process with a physical sintering process. Instead of using chemical solutions to remove material and form wiring patterns, the invention applies a conductive paste containing sub-micron silver particles and metal oxide particles, then heats it to sinter the particles into conductive wiring patterns directly on the substrate, eliminating the need for etching chemicals and reducing material waste
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 approach enables the production of conductive materials with low electric resistance and high bonding strength, reducing the risk of void formation and enhancing the reliability of electronic and light-emitting devices by eliminating the need for adhesives and minimizing gas-related issues.
Implementation Method 1
A method involving the sintering of silver particles with a median diameter of 0.1 μm to 15 μm in the presence of a metal oxide or oxygen at temperatures between 150°C to 320°C
Implementation Method 2
sintering of silver particles with a median diameter of 0.1 μm to 15 μm in the presence of a metal oxide or oxygen
Data Source
AI summary
An object of the present invention is to provide a method for producing a conductive material that allows a low electric resistance to be generated, and that is obtained by using an inexpensive and stable conductive material composition containing no adhesive. The conductive material can be provided by a producing method that includes the step of sintering a first conductive material composition that contains silver particles having an average particle diameter (median diameter) of 0.1 μm to 15 μm, and a metal oxide, so as to obtain a conductive material. The conductive material can be provided also by a method that includes the step of sintering a second conductive material composition that contains silver particles having an average particle diameter (median diameter) of 0.1 μm to 15 μm in an atmosphere of oxygen or ozone, or ambient atmosphere, at a temperature in a range of 150° C. to 320° C., so as to obtain a conductive material.