Coumarin Solder Paste Composition for Stable Reflow Supply
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Solution Overview
Problem
In reflow soldering, flux residues degrade insulation reliability and can peel off from electronic circuit boards, causing instability in solder paste supply due to separation of coumarin and solder powder in solder pastes containing coumarin derivatives.
Innovation Solution
A flux composition combining coumarin with a monoamide-based thixotropic agent, within specific content ratios, to suppress separation and reduce flux residues, comprising 10-40 wt% coumarin, 5-30 wt% monoamide thixotropic agent, and 40-80 wt% solvent, with optional activator and rosin, to stabilize solder paste supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If coumarin is added to reduce flux residues, then flux residue is reduced, but separation between coumarin and solder powder occurs causing supply stability deterioration
Solution Approach 1:
A coupling agent is introduced as an intermediary substance between coumarin and solder powder. The coupling agent has affinity for both coumarin and solder powder, forming a bridge that prevents separation while maintaining the flux residue reduction benefits of coumarin.
Solution Approach 2:
The invention creates a composite material system consisting of coumarin, solder powder, and coupling agent. This composite structure ensures uniform distribution and stable suspension of coumarin particles among solder powder particles, preventing separation during storage and application while maintaining the desired flux residue reduction properties.
2Object-generated harmful factors
If coumarin content is increased to reduce flux residues, then flux residue is reduced, but supply properties of solder paste deteriorate
Solution Approach 1:
The coupling agent serves as a mediator that enables higher coumarin content to be incorporated into the solder paste without compromising supply properties. It maintains uniform distribution and prevents agglomeration, ensuring smooth dispensing and printing even with increased coumarin concentration.
3Object-generated harmful factors
If coumarin and solder powder are mixed in solder paste, then flux residue is reduced, but separation occurs causing reliability issues
Solution Approach 1:
The coupling agent acts as a reliability-enhancing intermediary that bonds coumarin and solder powder together. This prevents separation during storage, transport, and application, ensuring consistent performance and reliable soldering results while maintaining the flux residue reduction benefits.
Solution Approach 2:
The invention develops a composite material formulation where coumarin, solder powder, and coupling agent form a stable integrated structure. This composite approach ensures uniform properties throughout the solder paste, preventing segregation and maintaining reliability across different batches and storage conditions.
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 composition effectively reduces flux residues and enhances the stability of solder paste supply during reflow soldering, preventing separation and ensuring reliable soldering performance.
Implementation Method 1
a monoamide-based thixotropic agent, within specific content ratios, to suppress separation and reduce flux residues
Implementation Method 2
Coumarin is a compound that is solid at normal temperature, but has high sublimability. Thus, solder pastes containing a flux containing coumarin have been expected to reduce flux residues.
Data Source
Figure 1
AI summary
A flux for soldering contains 10 to 40 wt% of coumarin, 5 to 30 wt% of a monoamide-based thixotropic agent and 40 to 80 wt% of a solvent. A solder paste contains the flux and a solder powder. A method for producing a soldered product includes a step of supplying the solder paste to a soldering portion of an electronic circuit board, a step of mounting an electronic component onto the soldering portion and a step of heating the soldering portion up to a temperature at which the solder powder melts in a reducing atmosphere containing a reducing gas to join the electronic component and the electronic circuit board.