Solder Paste Flux Composition for Void-Suppressed Wetting
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Solution Overview
Problem
The generation of voids in solder joint portions during soldering using fluxes containing surfactants as essential components is a significant challenge, as surfactants themselves contribute to void formation, necessitating the development of techniques to suppress this issue.
Innovation Solution
Incorporating 2-hydroxyisobutyric acid (HBA) into the flux, along with cationic and nonionic surfactants within specific weight percentage ranges, along with optional co-activators, to create a flux that effectively reduces void generation while maintaining solder wettability and oxide reduction capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a surfactant is added to flux to improve solder wettability, then the wettability of solder is improved, but voids are generated in the solder joint portion
Solution Approach 1:
The patent changes the chemical parameters of the flux by adding 2-hydroxyisobutyric acid (HBA) at specific concentrations (0.1-20 wt%) to modify the flux composition. This parameter change allows the flux to maintain good solder wettability while suppressing void generation, as HBA interacts with the surfactant components to reduce their harmful effects without compromising their wettability-enhancing function.
Solution Approach 2:
The patent creates a composite flux system by combining multiple components: surfactants (for wettability), 2-hydroxyisobutyric acid (for oxide removal and void suppression), and other auxiliary agents. This composite formulation allows the flux to simultaneously achieve multiple functions - maintaining excellent solder wettability while suppressing void generation through the synergistic interaction of its components.
2Reliability
If an activator is added to flux to remove metal oxides, then oxide removal capability is improved, but corrosion of metallic surfaces may occur
Solution Approach 1:
The patent uses 2-hydroxyisobutyric acid (HBA) as a controlled-activity activator. By adjusting its concentration within specific ranges (0.1-20 wt%) and controlling its molecular structure, the flux achieves effective oxide removal while limiting excessive corrosiveness. The specific chemical parameters of HBA provide balanced reactivity that removes oxides without aggressively attacking the metallic substrate.
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 proposed flux composition significantly suppresses void generation in solder joint portions, achieving improved soldering quality by optimizing the content of HBA, cationic surfactants, nonionic surfactants, and co-activators, which helps in removing oxides without corroding the metallic surfaces.
Implementation Method 1
the acid anhydride absorbs water and thereby functions as an activator
Implementation Method 2
The flux chemically removes metal oxides that are present on the surface of solder and metal oxides present on the metallic surface of a subject of soldering
Implementation Method 3
The surfactant is added to make a low-molecular-weight polar molecule such as water compatible with the flux components
Data Source
AI summary
A flux containing 0.1 to 20 wt% of 2-hydroxyisobutyric acid as an activator, 10 to 60 wt% of a cationic surfactant and 5 to 60 wt% of a nonionic surfactant. A solder paste contains this flux and a metal powder.