Resin Flux Cored Solder Composition for Scatter Suppression
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Solution Overview
Problem
Resin flux cored and flux coated solders face issues with flux and solder scattering during use, which can lead to short circuits and contamination, and existing solutions restrict the optimization of flux components based on solder alloy types and joining conditions, while also making it difficult to process due to low viscosity states.
Innovation Solution
A flux comprising specific polymers, such as acrylic and vinyl ether polymers, with weight average molecular weights between 8000 and 100000, and rosin resins, which improves scattering prevention and processability by maintaining a solid or high viscosity state at room temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a flux is in a low viscosity liquid state, then it is easy to process and fill, but it causes scattering of flux and solder leading to short circuits and contamination
Solution Approach 1:
The patent changes the viscosity parameter of the flux by adding a specific thickening agent (polyacrylic acid or polyacrylamide) to achieve optimal viscosity at room temperature. This prevents scattering while maintaining processability during soldering operations.
Solution Approach 2:
The patent creates a composite flux system by combining traditional flux components (rosin, activator, solvent) with a thickening agent (polyacrylic acid or polyacrylamide). This composite structure provides both the chemical activity needed for soldering and the physical viscosity control to prevent scattering.
2Reliability
If a flux is in a solid or high viscosity liquid state at room temperature, then scattering is prevented, but it becomes difficult to process to arbitrary size and shape
Solution Approach 1:
The patent optimizes the viscosity parameter within a specific range (100-10,000 cP at room temperature) to balance scattering prevention with processability. This controlled viscosity range allows the flux to maintain its position while still being workable during manufacturing and application.
Solution Approach 2:
The patent applies different properties to different aspects of the flux: high viscosity for stability and scattering prevention, but controlled flow characteristics for processability. The thickening agent provides localized viscosity enhancement without completely eliminating flow capability.
3Reliability
If conventional flux components (rosin resin and activator) are limited to specific components, then gas release is controlled, but optimization of flux components according to solder alloy type and joining conditions is restricted
Solution Approach 1:
The patent introduces a universal thickening agent (polyacrylic acid or polyacrylamide) that can be applied across different solder alloy types and joining conditions. This universal component provides consistent viscosity control and scattering prevention while allowing other flux components to be optimized for specific applications.
Solution Approach 2:
The patent separates the function of gas release control (handled by traditional flux components like rosin and activator) from the function of viscosity control and scattering prevention (handled by the thickening agent). This functional segmentation allows independent optimization of each aspect.
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 suppresses flux and solder scattering, enhances processability, and prevents sticking to electronic components, ensuring reliable soldering operations.
Implementation Method 1
The flux in resin flux cored solder or flux coated solder removes chemically a metal oxide present on the solder and the metal surface to be soldered at the time of soldering
Implementation Method 2
By using the flux, an intermetallic compound is formed between the solder and the metal surface to be soldered, so that strong joint may be obtained
Data Source
Figure 1
AI summary
An object of the present invention is to provide a resin flux cored solder, or a flux coated solder, for which scattering of flux and solder in using the solder is suppressed, and a flux to be contained therein. A flux for a resin flux cored solder comprising a rosin resin, an activator, and at least one selected from an acrylic polymer and a vinyl ether polymer, which has a weight average molecular weight of 8000 to 100000, in an amount of 0.1 to 3 mass-% based on the total mass of the flux.