Copper-Particle Wiring Substrate for Low-Shrinkage Via Adhesion
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Solution Overview
Problem
Existing wiring substrates and light-emitting devices face challenges in reliability due to issues with volumetric shrinkage and adhesiveness in the conductive and wiring portions, which affect the stability and connection strength of components like light-emitting elements.
Innovation Solution
A wiring substrate with a base body having via holes filled with a conductive paste containing copper particles of specific size ranges, where the weight proportion of small-sized particles is lower in the conductive paste within the via holes and higher in the surface wiring paste, improving connection stability and adhesiveness through the anchor effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conductive paste with uniform particle size distribution is used in both via holes and surface wirings, then manufacturing process is simple, but volumetric shrinkage is excessive and adhesiveness is poor
Solution Approach 1:
The patent applies different particle size distributions to different locations: via holes contain conductive paste with smaller particle sizes (0.1-1.0 μm dominant) for low shrinkage, while surface wirings contain conductive paste with larger particle sizes (1.0-10 μm dominant) for high adhesiveness. This local differentiation resolves the contradiction by optimizing each location's particle distribution for its specific functional requirements.
Solution Approach 2:
The patent changes the particle size distribution parameter of the conductive paste between different locations and layers. By controlling the weight proportion of small-sized particles to be lower in surface wiring paste than in via hole paste, the patent achieves different volumetric shrinkage and adhesiveness characteristics appropriate for each location, thereby improving overall reliability.
2Stability of the object's composition
If high proportion of small-sized copper particles is used in conductive paste, then volumetric shrinkage is reduced, but adhesiveness deteriorates
Solution Approach 1:
The patent applies different particle size distributions to different locations: via holes contain conductive paste with smaller particle sizes (0.1-1.0 μm dominant) for low shrinkage, while surface wirings contain conductive paste with larger particle sizes (1.0-10 μm dominant) for high adhesiveness. This local differentiation resolves the contradiction by optimizing each location's particle distribution for its specific functional requirements.
Solution Approach 2:
The patent uses a balanced particle size distribution rather than extreme values. In via holes, small particles dominate but large particles are present (30-70 wt% small, 30-70 wt% large). In surface wirings, the distribution is inverted (10-40 wt% small, 60-90 wt% large). This partial action approach achieves both low shrinkage and high adhesiveness without using extreme particle size ratios.
3Strength
If high proportion of large-sized copper particles is used in conductive paste, then adhesiveness is improved, but volumetric shrinkage increases
Solution Approach 1:
The patent applies different particle size distributions to different locations: via holes contain conductive paste with smaller particle sizes (0.1-1.0 μm dominant) for low shrinkage, while surface wirings contain conductive paste with larger particle sizes (1.0-10 μm dominant) for high adhesiveness. This local differentiation resolves the contradiction by optimizing each location's particle distribution for its specific functional requirements.
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 solution enhances the reliability of the wiring substrate and light-emitting device by reducing volumetric shrinkage and improving adhesiveness, leading to stable connections and enhanced performance.
Implementation Method 1
firing the second conductive paste
Implementation Method 2
copper particles including small-sized particles with a particle size in a range from 0.1 μm to 1.0 μm and large-sized particles with a particle size in a range from more than 1.0 μm to 10 μm
Implementation Method 3
first conductive member containing copper particles and a first resin; second conductive member containing copper particles
Data Source
AI summary
A wiring substrate including a base body provided with a via hole, a conductive portion disposed in the via hole, and a wiring portion electrically connected to the conductive portion and disposed on a surface of the body. The conductive portion includes a first conductive member containing copper particles and a resin. The first member contains small-sized particles with a particle size from 0.1 μm to 1.0 μm and large-sized particles with a particle size from more than 1.0 μm to 10 μm. The wiring portion includes a second conductive member containing copper particles. The second member contains small-sized particles with a particle size from 0.1 μm to 1.0 μm and large-sized particles with a particle size from more than 1.0 μm to 10 μm. A weight proportion of the small-sized particles in the first member is lower than a weight proportion of the small-sized particles in the second member.