Cu-OSP Flux Composition for Direct Soldering
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Solution Overview
Problem
The existing flux compositions require an additional step to remove the Cu-OSP film from substrates before soldering, which is inefficient and costly.
Innovation Solution
A flux composition containing rosin, an organic acid, a benzimidazole-based compound, and a solvent, with specific mass ratios, that allows for soldering on Cu-OSP processed substrates without the need to remove the Cu-OSP film, using 2-alkylbenzimidazole or its salt, and optionally additional imidazole-based compounds and amine hydrohalide salts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional flux compositions are used for soldering on Cu-OSP processed substrates, then the soldering process can be completed, but an additional step to remove the Cu-OSP film is required before soldering
Solution Approach 1:
The patent combines the Cu-OSP film removal function and soldering activation function into a single flux composition. The flux simultaneously removes the organic solderability preservative film and activates the copper surface for soldering, eliminating the need for separate film removal and activation steps that were previously required
Solution Approach 2:
The flux composition is designed to perform multiple functions: it acts as both a film remover for Cu-OSP processed substrates and an activator for copper surface preparation. This multi-functional flux can handle both OSP film removal and subsequent soldering activation in one application, making the process more efficient and reducing the number of required process steps
2Reliability
If an additional Cu-OSP film removal step is implemented, then complete surface preparation is achieved, but process time and cost increase
Solution Approach 1:
The patent merges the film removal action and surface activation action into a single flux application step. The flux composition contains ingredients that simultaneously dissolve the Cu-OSP film and activate the copper surface, achieving complete surface preparation without requiring sequential separate steps, thereby reducing total process time while maintaining reliability
3Ease of manufacture
If conventional flux is used on Cu-OSP substrates, then standard soldering can proceed, but excessive residue remains causing contact and conduction failures
Solution Approach 1:
The patent modifies the chemical composition parameters of the flux to achieve better residue removal properties. By adjusting the types and ratios of activators, solvents, and other ingredients, the flux is optimized to minimize harmful residues while maintaining effective Cu-OSP film removal and soldering activation, thereby preventing contact and conduction failures
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
Enables soldering on Cu-OSP substrates without the extra film removal step, reducing costs and ensuring good wettability and residue removal, thus preventing contact and conduction failures.
Implementation Method 1
a flux containing an activator for removing an oxide film from a metal surface
Implementation Method 2
removing any metal oxide, inhibiting reoxidation when the solder melts, reducing surface tension of the solder
Data Source
AI summary
Provided is a flux that allows soldering to be performed without requiring a step of removing a Cu-OSP film even with a Cu-OSP processed substrate. This flux containing rosin, an organic acid, a benzimidazole-based compound, and a solvent is characterized in that 30% by mass or more and 70% by mass or less of the rosin, 1% by mass or more and 10% by mass or less of the organic acid, 0.2% by mass or more and 10% by mass or less of the benzimidazole-based compound, and 20% by mass or more and 60% by mass or less of the solvent, wherein the benzimidazole-based compound is composed of at least one of 2-alkylbenzimidazole and a salt of 2-alkylbenzimidazole hydrohalide.