Flux Composition for Low-Void Solder Paste Printability
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Solution Overview
Problem
Existing solder pastes fail to adequately reduce void area ratios in solder joints, especially when used with larger electronic components, and often compromise printability in the process.
Innovation Solution
A flux and solder paste composition that includes a combination of rosin and acrylic resins as base resins, specific activators, solvents, and additives like trimethylolpropane, trimethylolethane, and di(trimethylolpropane, which are blended in specific ratios to enhance solder joint quality and maintain printability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional flux compositions are used to reduce void area ratio, then void area ratio decreases, but printability deteriorates
Solution Approach 1:
The invention changes the chemical composition parameters of the flux by incorporating specific compounds (polyol compounds with 3-6 carbon atoms and carboxylic acid compounds with 4-6 carbon atoms) in optimized proportions. This parameter optimization reduces void formation while preserving printability, resolving the contradiction between reliability improvement and ease of operation maintenance.
Solution Approach 2:
The invention creates a composite flux system combining multiple components: rosin-based base resin, polyol compounds, carboxylic acid compounds, and solvents. This composite formulation achieves synergistic effects where each component contributes to both void reduction and printability maintenance, resolving the technical contradiction.
2Reliability
If flux additives are increased to reduce voids, then void area ratio decreases, but solder paste composition complexity increases
Solution Approach 1:
The polyol compounds and carboxylic acid compounds serve multiple functions simultaneously: they act as void-preventing agents, flux components, and composition simplifiers. This multi-functionality reduces the need for separate additive components, thereby reducing overall composition complexity while maintaining void reduction effectiveness.
Solution Approach 2:
The invention optimizes the concentration parameters of key components to achieve effective void reduction without requiring excessive amounts of additives. By finding the optimal parameter range, the composition remains relatively simple while achieving the desired reliability improvement.
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 and solder paste effectively reduce void area ratios in solder joints, even on larger electronic components, while ensuring good printability by optimizing the composition and blending amounts of base resins, activators, solvents, and additives.
Implementation Method 1
The flux contained in a solder paste removes the oxide film adhered to the conductor pattern on an electronic circuit board or the electrodes of electronic components during the heating process
Implementation Method 2
the components such as a solvent and an activator contained in the flux are volatilized and decomposed during the heating process to generate a gas
Implementation Method 3
the components such as a solvent and an activator contained in the flux are volatilized and decomposed during the heating process to generate a gas
Implementation Method 4
a solder joint formed by melting and aggregation/solidification of a solder alloy powder
Implementation Method 5
a solder joint formed by melting and aggregation/solidification of a solder alloy powder
Data Source
AI summary
[Object] To provide a flux and a solder paste which reduce the void area ratio in a solder joint, and ensures good printability. [Resolution means] A flux including a base resin, an activator, a solvent, and an additive, the additive being at least one of the compound represented by the general formula (1) and the compound represented by the general formula (2), the additive being present in an amount of 0.5% by mass or more and 12% by mass or less with reference to the total amount of the flux: wherein R1 is a methyl group, an ethyl group, or a hydroxymethyl group, R2 is a hydroxymethyl group or a carboxyl group, R3 is a hydroxymethyl group or two R3s together form one or more repeating units symmetrically linking together through CH2-O-CH2, and at least one of Rl, R2, and R3 is a hydroxymethyl group. wherein R4 and R5 are the same or different kinds of alkyl groups.