Flux Composition to Suppress Solder Bridges and Balls

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Solution Overview

Problem

Conventional fluxes used in flow soldering methods often result in the unwanted phenomena of solder bridges and balls between adjacent electronic components, which are not effectively suppressed by existing formulations.

Innovation Solution

A flux composition containing specific amounts of an organochlorine compound, amine hydrochloride, and organophosphorus compounds, such as phosphonic acid esters and phenyl-substituted phosphinic acids, is developed to prevent the occurrence of solder bridges and balls during soldering.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional flux formulations are used, then soldering can be performed, but solder bridges and balls occur between adjacent electronic components

Engineering Contradiction:
Improvesoldering reliabilityVSAvoidsolder bridges and balls
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The invention changes the chemical composition parameters of the flux by incorporating specific organophosphorus compounds (phosphonic acid esters and phenyl-substituted phosphinic acids) in controlled amounts (0.2-1.5 mass% and 0.1-1.0 mass% respectively), along with amine hydrochloride (0.1-5.0 mass%), to modify the flux's interaction with solder and prevent bridge and ball formation

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention creates a composite flux formulation combining multiple chemical components with specific functions: organophosphorus compounds for suppressing bridges and balls, amine hydrochloride for activation, and other auxiliary components, where each component contributes to the overall performance of preventing solder defects

Inventive Principle:
Principle #40Composite materials

2Manufacturing precision

If flux composition is modified to suppress bridges and balls, then soldering quality improves, but formulation complexity increases

Engineering Contradiction:
Improvesoldering precisionVSAvoidflux formulation complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The invention establishes specific parameter ranges for each chemical component to achieve the desired effect while maintaining formulation manageability. The controlled amounts of organophosphorus compounds and amine hydrochloride provide precise control over flux behavior without requiring overly complex formulations

Inventive Principle:
Principle #35Parameter changes

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 proposed flux composition effectively suppresses the formation of solder bridges and balls, enhancing the reliability and efficiency of the soldering process by ensuring better wetting and interfacial tension control.

Implementation Method 1

an interfacial tension lowering action (action of reducing surface tension of molten solder and enhancing wettability of metal surface with solder)

Methodology Applied
Scientific EffectSurface tension lowering: Surfactant

Implementation Method 2

an reoxidation-preventing action (action of covering cleaned metal surface during soldering, blocking contact with oxygen, and preventing metal surface from being reoxidized by heating)

Methodology Applied
Scientific EffectReoxidation prevention: Oxidation

Implementation Method 3

a metal surface cleaning action (action of chemically removing oxide films on metal surfaces of printed board and electronic component to clean surfaces so that the surfaces can be soldered)

Methodology Applied
Scientific EffectMetal surface cleaning: Chemical Bonding

Data Source

PatentEP3698913B1Flux and resin composition for flux
Publication Date: 2022.01.19 SENJU METAL IND CO LTD

AI summary

An object of the present invention is to provide a flux in which the occurrence of a bridge and a ball is suppressed at the time of soldering, and a resin composition for the flux. The flux comprising: at least one selected from 0.3 to 2.0 mass% of an organochlorine compound, and more than 0.04 mass% and 1.00 mass% or less of an amine hydrochloride; and 0.2 to 1.5 mass% of an organophosphorus compound that is at least one selected from a phosphonic acid ester and a phenyl-substituted phosphinic acid, each based on the whole flux.