Flux Composition for Soldering Wetting and Dewetting Control
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Solution Overview
Problem
Conventional fluxes with dimer acids exhibit varying wetting and spreading properties due to differences in carbon atoms and unsaturation levels, leading to inconsistent soldering finishes and potential dewetting issues across different heat histories.
Innovation Solution
A flux comprising 0.5 wt % to 20 wt % of dimer or trimer acids derived from oleic and linoleic acids, along with hydrogenated variants, combined with rosin, solvent, organic acids, amines, and thixotropic agents, to enhance wetting, spreading, and suppress dewetting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional fluxes use dimer acids with varying carbon atoms and unsaturation levels, then the flux can be manufactured with different properties, but the wetting and spreading properties become inconsistent and dewetting occurs
Solution Approach 1:
The patent specifies precise parameter ranges for dimer acid composition (0.5-20 wt%) and restricts the types of monocarboxylic acids used in dimerization to those with 10-20 carbon atoms and specific unsaturation levels. This parameter control ensures consistent wetting and spreading properties while maintaining manufacturing flexibility within defined boundaries.
Solution Approach 2:
The flux comprises a composite formulation combining dimer acids (from specific monocarboxylic acid dimerization) with trimer acids and hydrogenated variants. This composite approach balances the reactive properties needed for metal oxide removal with the stability required to prevent dewetting, achieving both versatility and reliability.
2Ease of manufacture
If dimer acid structure varies due to different degree of unsaturation, then the chemical properties change, but the soldering finish quality becomes unstable
Solution Approach 1:
The patent defines specific parameter ranges for the monocarboxylic acids used in dimerization: 10-20 carbon atoms and controlled unsaturation levels. By constraining these parameters, the invention maintains manufacturing flexibility in producing different dimer acids while ensuring they all deliver stable soldering finishes within the specified composition range.
Solution Approach 2:
The invention applies local quality control by specifying particular properties for the dimer acid components (carbon atom count, unsaturation level) while allowing variation in other aspects. This enables manufacturers to produce dimer acids with different local characteristics (from different starting acids) while maintaining overall consistent soldering performance through the controlled composition range.
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 ensures consistent wetting and spreading even under high thermal loads, effectively preventing dewetting and providing a stable soldering finish across various heat histories.
Implementation Method 1
a flux used for soldering chemically removes a metal oxide present on a solder and the metal surface of a joining object to be soldered
Implementation Method 2
the solder wets and spreads well and the occurrence of dewetting can be suppressed
Data Source
AI summary
Provided are a flux having improved wetting and spreading properties and capable of suppressing the occurrence of dewetting and a solder paste using this flux. The flux includes a total amount of 0.5 wt % or more and 20 wt % or less of: any of a dimer acid which is a reaction product of oleic acid and linoleic acid, a trimer acid which is a reaction product of oleic acid and linoleic acid, a hydrogenated dimer acid obtained by adding hydrogen to a dimer acid which is a reaction product of oleic acid and linoleic acid, or a hydrogenated trimer acid obtained by adding hydrogen to a trimer acid which is a reaction product of oleic acid and linoleic acid; or two or more of a dimer acid which is a reaction product of oleic acid and linoleic acid, a trimer acid which is a reaction product of oleic acid and linoleic acid, a hydrogenated dimer acid obtained by adding hydrogen to a dimer acid which is a reaction product of oleic acid and linoleic acid, and a hydrogenated trimer acid obtained by adding hydrogen to a trimer acid which is a reaction product of oleic acid and linoleic acid. The solder paste includes this flux and a metal powder.