Metallic Nano-particle Paste for LED Mounting
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Solution Overview
Problem
Conventional methods for mounting LED chips on substrates using solder paste face issues with flux residue affecting bonding reliability and precision, leading to potential short circuits and yield deterioration due to large microscopic solder particles.
Innovation Solution
A method employing a metallic nano-particle paste with small particle diameters is used, allowing for precise coating and bonding at lower temperatures without flux, forming an alloy between the nano-particles and the substrate to enhance bonding reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solder paste containing flux is used for mounting LED chip, then bonding between LED chip and substrate is achieved, but flux residue remains and deteriorates bonding reliability
Solution Approach 1:
The invention extracts and removes the flux component from the solder paste, creating a new mounting paste that contains only metallic particles and binder without flux. This eliminates the source of flux residue that deteriorates bonding reliability while maintaining the bonding function through alternative mechanisms.
Solution Approach 2:
The invention changes the chemical composition parameters of the mounting paste by eliminating flux and adjusting the binder content to 5-30 mass%. This parameter change transforms the paste from a flux-based bonding mechanism to a binder-based mechanism, preventing harmful residue formation while achieving reliable bonding.
2Manufacturing precision
If conventional solder paste with large microscopic particles (2-50 μm) is used, then coating is performed, but precise transfer through metallic mask fails and yield deteriorates
Solution Approach 1:
The invention changes the particle size parameter from conventional 2-50 μm to nanometer scale (1-100 nm, preferably 5-50 nm). This dramatic reduction in particle size enables the paste to pass through metallic mask openings with high precision, achieving accurate transfer patterns and preventing short circuits, thereby improving both manufacturing precision and yield.
Solution Approach 2:
The invention segments the solder material into ultra-fine nanometer-sized particles rather than using conventional large microscopic particles. This segmentation into smaller units enables better flow characteristics through the mask and more precise deposition, resolving the transfer precision problem.
3Manufacturing precision
If metallic nano-particle paste with small average particle diameter is used, then high-precision coating is achieved, but bonding temperature requirement increases
Solution Approach 1:
The invention changes the binder composition parameters by selecting specific polymers (polyester, polyurethane, epoxy, phenolic, or acrylic resin) and controlling binder content at 5-30 mass%. This optimized binder system provides sufficient bonding strength at lower temperatures, compensating for the reduced thermal mass of nano-particles and enabling effective bonding without excessive temperature 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
This approach enables high-precision coating and robust bonding between the LED chip and substrate, preventing short circuits and improving yield by eliminating flux residue and requiring lower temperatures for bonding.
Implementation Method 1
heating the mount layer and the metallic nano-particle paste to form an alloy, thereby bonding the luminescent device and the substrate
Data Source
AI summary
A method for mounting a luminescent device having a mount layer on a substrate, comprising the steps of coating a metallic nano-particle paste on the substrate, disposing the mount layer of the luminescent device on the metallic nano-particle paste, and heating the mount layer and the metallic nano-particle paste to form an alloy, thereby bonding the luminescent device and the substrate.