Solder Flux Composition for Stable Wetting and Low Voiding
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Solution Overview
Problem
Existing soldering fluxes face challenges in achieving stable wet spreadability and reducing void generation, particularly due to variations in heating history and the inefficacy of organic acids, amines, and halogens in improving wetting and reducing voids.
Innovation Solution
A flux comprising rosin, tris(2-carboxyethyl) isocyanurate, and optional activators, thixotropic agents, and antioxidants, with tris(2-carboxyethyl) isocyanurate content between 0.1 wt% to 15 wt%, which enhances solder wettability and reduces void formation by removing oxides during soldering in a reflow furnace.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fluxes with organic acids, amines, and halogens are used to improve activity, then some wetting improvement is achieved, but void generation is not sufficiently reduced and wet spreadability varies with heating history
Solution Approach 1:
The patent changes the chemical composition parameters of the flux by incorporating tris(2-carboxyethyl) isocyanurate at 0.1-15 wt%, combined with specific ratios of rosin (10-50 wt%) and solvents (30-60 wt%). This parameter change in flux composition fundamentally alters the chemical activity and oxide removal capability, achieving both reduced void generation and stable wet spreadability regardless of heating history variations.
Solution Approach 2:
The patent creates a composite flux system by combining multiple components: tris(2-carboxyethyl) isocyanurate, rosin, solvent, and optional additives (activators, thixotropic agents, antioxidants). This composite formulation synergistically addresses both void reduction and wet spreadability stability, overcoming the limitations of single-component or simple multi-component conventional fluxes.
2Manufacturing precision
If heating history is controlled to achieve consistent soldering finish, then wet spreadability can be maintained, but process complexity and manufacturing constraints increase
Solution Approach 1:
The flux composition with tris(2-carboxyethyl) isocyanurate and rosin provides self-regulating chemical activity that adapts to different heating histories. The flux automatically maintains effective oxide removal and wet spreadability across a range of heating conditions without requiring precise control, making the process self-adapting and reducing manufacturing complexity.
Solution Approach 2:
By changing the chemical parameters of the flux (specifically incorporating tris(2-carboxyethyl) isocyanurate), the patent expands the process window for effective soldering. This allows consistent soldering finishes to be achieved across varied heating histories without increasing process control complexity.
3Reliability
If tris(2-carboxyethyl) isocyanurate content is increased to improve wettability, then oxide removal effectiveness increases, but flux cost and potential residue issues may worsen
Solution Approach 1:
The patent optimizes the concentration parameter of tris(2-carboxyethyl) isocyanurate within the specific range of 0.1-15 wt%. This parameter optimization achieves effective oxide removal and wettability improvement while controlling flux residue formation. The balanced formulation ensures sufficient activity without excessive residue, addressing both wettability and residue concerns.
Solution Approach 2:
The flux formulation provides localized chemical activity where tris(2-carboxyethyl) isocyanurate concentrates at the solder-metallization interface to effectively remove oxides and improve wettability. The overall flux composition is balanced to ensure this localized high activity does not result in excessive bulk residue, achieving effective local action with controlled global residue.
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 flux improves solder wet spreadability and reduces void generation, ensuring consistent soldering performance regardless of heating history and enhancing the wettability of solder to joining components.
Implementation Method 1
a flux used for soldering has an effect of chemically removing metal oxides present on surfaces of solder and metal
Implementation Method 2
tris(2-carboxyethyl) isocyanurate...oxides which cause non-wetting of solder are removed by performing soldering in a reflow furnace
Data Source
Figure 1A~1C
Figure 1D~2B
Figure 2C~3B
AI summary
Provided are flux in which solder wettability is improved, and a solder paste in which the flux is used. The flux contains 0.5-20.0 wt% of a (2-carboxyalkyl)isocyanurate adduct, and 5.0-45.0 wt% of a rosin, and furthermore contains a solvent. The (2-carboxyalkyl)isocyanurate adduct is a mono(2-carboxyalkyl)isocyanurate adduct, a bis(2-carboxyalkyl)isocyanurate adduct, a tris(2-carboxyalkyl)isocyanurate adduct, or a combination of two or more of these.