Metal Powder for Flexible PCB Sintered Bodies
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Metal sintered bodies with low porosity lack flexibility due to stress concentration at pores, leading to potential disconnection of conductive patterns in flexible printed circuit boards during bending.
Innovation Solution
A metal powder with a mean particle size of 1-200 nm and a mean crystallite size of 20 nm or less, manufactured using a liquid-phase reduction method with a reducing agent at 100°C or lower, resulting in a sintered body with a crystallite-to-particle size ratio less than 0.4, which forms fine cracks to relieve stress and enhance flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the porosity of a sintered body layer is set to 1% or less to improve adhesion, then adhesion is improved, but the sintered body becomes easily broken and lacks flexibility
Solution Approach 1:
The invention changes the particle size parameters of the metal powder used in the ink. Specifically, it uses metal powder with a mean particle size of 0.5 μm or less and a specific surface area of 10 m²/g or more, which allows forming a sintered body with appropriate porosity that balances adhesion and flexibility
Solution Approach 2:
The invention uses an excessive amount of metal powder (high solid content) in the ink formulation. This ensures that even after sintering, there are enough pores remaining to provide flexibility while maintaining sufficient adhesion, effectively over-compensating for the adhesion requirement
2Adaptability or versatility
If metal powder with small particle size is used to improve flexibility, then flexibility is improved, but manufacturing precision and particle size control become more difficult
Solution Approach 1:
The invention specifies precise particle size parameters (mean particle size of 0.5 μm or less, specific surface area of 10 m²/g or more) to achieve the desired flexibility while maintaining manufacturability. These parameter ranges are optimized to balance flexibility improvement with manufacturing feasibility
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 resulting sintered body exhibits good flexibility and fatigue strength, preventing disconnection of conductive patterns during bending, as demonstrated by repeated bending tests on printed circuit boards.
Implementation Method 1
a step of reducing a metal ion with a reducing agent in an aqueous solution, in which the reduction step is conducted at 100° C. or lower
Data Source
AI summary
An object of the present invention is to provide a metal powder and an ink with which a sintered body having good flexibility can be formed, and a sintered body having good flexibility. A metal powder according to an embodiment of the present invention has a mean particle size D50BET of 1 nm or more and 200 nm or less as calculated by a BET method, a mean crystallite size DCryst of 20 nm or less as determined by an X-ray analysis, and a ratio (DCryst/D50BET) of the mean crystallite size DCryst to the mean particle size D50BET of less than 0.4.