Nanoparticle Metal Bonding Paste for Edge Void Reduction
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Solution Overview
Problem
Conventional bonding methods using lead-free high-temperature solder face challenges in forming a uniform metal bonding layer with reduced voids, particularly at the edge, which can lead to adhesion failure and oxidation when exposed to large bonding areas and high temperatures.
Innovation Solution
A metal paste containing metal nanoparticles with specific size and thermal properties, combined with solvents and additives, is applied to form a uniform bonding layer by sintering at controlled temperatures, reducing voids and enhancing bonding strength across large areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional lead-free high-temperature solder is used for bonding, then bonding strength is improved, but void formation at edges increases and adhesion failure occurs
Solution Approach 1:
The patent changes the particle size parameter of metal particles from conventional micron-scale to nano-scale (10-100 nm number average primary particle size), which fundamentally alters the sintering behavior and void formation characteristics, enabling uniform bonding layers without edge voids while maintaining high bonding strength
Solution Approach 2:
The patent creates a composite paste system combining metal nanoparticles with specifically selected solvents and additives, where the synergistic interaction between components controls solvent evaporation and sintering processes to eliminate edge voids while preserving bonding strength
2Productivity
If bonding area is increased, then mounting density is improved, but void formation at edges increases and adhesion failure occurs
Solution Approach 1:
By changing the particle size parameter to nano-scale and controlling the solvent composition, the paste maintains uniform rheological properties and sintering behavior across large bonding areas, preventing edge void formation and adhesion failure even when mounting density is increased
Solution Approach 2:
The patent segments the solvent system into multiple components with different boiling points and evaporation rates, allowing controlled sequential evaporation that maintains paste uniformity across large bonding areas and prevents edge effects
3Strength
If high temperature treatment is applied, then bonding strength is improved, but void formation increases and oxidation risk increases
Solution Approach 1:
The patent performs preliminary action by carefully selecting and pre-mixing solvents and additives in specific proportions before sintering, creating a paste composition that controls evaporation and sintering sequences to minimize void formation and oxidation risk during high-temperature treatment
Solution Approach 2:
The patent creates an inert environment by selecting solvents and additives that form protective atmospheres during heating, and by controlling the paste composition to minimize oxidation reactions, thereby reducing oxidation risk during high-temperature sintering while maintaining bonding strength
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 effectively reduces voids and ensures high bonding strength, even at edges, by controlling the thermal properties and composition of the paste, allowing for reliable bonding in high-temperature environments.
Implementation Method 1
a metal paste containing metal particles having a number average primary particle size of at least 10 to 100 nm... by sintering at controlled temperatures, reducing voids and enhancing bonding strength
Implementation Method 2
a cumulative weight loss value (L100) when a temperature is raised from 40° C. to 100° C. is 75 or less, and a cumulative weight loss value (L150) when a temperature is raised from 40° C. to 150° C. is 90 or more
Implementation Method 3
a cumulative weight loss value (L200) when a temperature is raised from 40° C. to 200° C. is 98 or more, based on 100 cumulative weight loss value (L700) when the paste is heated from 40° C. to 700° C.
Data Source
AI summary
There is provided a bonding paste capable of forming a uniform bonding layer by reducing occurrence of voids at edges even when a bonding area is large, and bonding method using the paste, and provides a metal paste for bonding containing at least metal nanoparticles (A) having a number average primary particle size of 10 to 100 nm, wherein a cumulative weight loss value (L100) when a temperature is raised from 40° C. to 100° C. is 75 or less, and a cumulative weight loss value (L150) when a temperature is raised from 40° C. to 150° C. is 90 or more, and a cumulative weight loss value (L200) when a temperature is raised from 40° C. to 200° C. is 98 or more, based on 100 cumulative weight loss value (L700) when the paste is heated from 40° C. to 700° C. at a heating rate of 3° C./min in a nitrogen atmosphere.