Flat-Surface Solder Particles for Reliable Anisotropic Connections
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Solution Overview
Problem
Anisotropic conductive materials with solder particles struggle to achieve reliable electrical connections and insulation due to inadequate conduction and insulation reliability, especially as circuit components miniaturize.
Innovation Solution
Solder particles with a flat portion on their surface, having a specific diameter and size distribution, are used to enhance contact area and wetting with electrodes, ensuring stable connections and reduced ion migration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional spherical solder particles are used in anisotropic conductive materials, then the material can be manufactured with standard processes, but the conduction reliability and insulation reliability are insufficient due to inadequate contact area and wetting with electrodes
Solution Approach 1:
The solder particle is designed with a flat portion on its surface while maintaining a substantially spherical overall shape. This local modification creates a specific flat area that enhances contact with electrodes during pressing, improving both conduction and insulation reliability without completely changing the particle morphology
Solution Approach 2:
The invention changes the surface geometry parameter of the solder particle by forming a flat portion with a specific diameter ratio (0.05 ≤ A/B < 1.0) relative to the particle diameter. This parameter change optimizes the contact area and wetting characteristics while maintaining manufacturability
2Reliability
If solder particles with larger flat portions are used to increase contact area, then conduction reliability improves, but the particles become difficult to manufacture with consistent size distribution
Solution Approach 1:
The flat portion is formed on the solder particles before they are mixed into the anisotropic conductive material. This preliminary surface treatment ensures that the particles have the optimal flat area for contact while maintaining a narrow size distribution (C.V. value of 20% or less), resolving the conflict between reliability and manufacturing precision
3Productivity
If the average particle diameter of solder particles is reduced to meet miniaturized circuit requirements, then connection density increases, but the contact area with electrodes becomes insufficient for reliable conduction
Solution Approach 1:
Even though the overall particle diameter is reduced (1 to 30 μm) to increase connection density, a flat portion is formed on each particle surface. This local flat area compensates for the reduced size, ensuring sufficient contact area and wetting with electrodes, thereby maintaining conduction reliability despite miniaturization
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 use of solder particles with a flat surface improves conduction and insulation reliability by increasing contact area, facilitating easier wetting and spreading, and preventing displacement, thus maintaining reliable connections between electrodes.
Implementation Method 1
facilitating easier wetting and spreading
Data Source
AI summary
The present invention relates to solder particles, each of which partially has a flat portion in the surface. By using these solder particles, electrodes facing each other are able to be appropriately connected, thereby achieving an anisotropic conductive material that exhibits excellent conduction reliability and excellent insulation reliability.