Perfluorinated Polyether Cover Layer for Lead-Free Wave Soldering
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Solution Overview
Problem
Wave soldering systems using lead-free solders face challenges with oxidation and contamination, particularly with lead-containing impurities accumulating in the solder bath, leading to quality issues and environmental concerns, which necessitate frequent bath replacements.
Innovation Solution
Applying a perfluorinated polyether cover layer to the solder bath, which binds and removes lead-containing impurities, extending the time between bath changes by incorporating the polyether into the solder wave or solder guide, thereby reducing oxide formation and contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lead-free solder is used in wave soldering, then environmental compliance and solder quality are improved, but lead-containing impurities accumulate in the solder bath leading to frequent bath replacements
Solution Approach 1:
A perfluorinated polyether substance is introduced as an intermediary agent into the solder bath. This substance selectively binds to lead-containing impurities through chemical interaction, forming removable complexes. The perfluorinated polyether acts as a mediator that captures harmful lead impurities from the lead-free solder bath, allowing extended operation without bath replacement while maintaining solder quality.
2Reliability
If the solder bath is replaced frequently to remove lead impurities, then solder quality is maintained, but operational costs and downtime increase
Solution Approach 1:
The perfluorinated polyether serves as a continuous impurity removal mechanism, eliminating the need for frequent bath replacements. By maintaining lead impurity levels below critical thresholds through chemical binding, the system sustains high productivity without compromising solder quality or requiring operational interruptions for bath changes.
Solution Approach 2:
The perfluorinated polyether is pre-introduced into the solder bath before lead impurities reach problematic levels. This preliminary action establishes a protective chemical environment that continuously captures lead impurities as they enter the bath, preventing quality degradation before it occurs and eliminating the need for reactive bath replacements.
3Reliability
If a perfluorinated polyether cover layer is applied to the solder bath, then oxide formation is reduced, but system complexity increases
Solution Approach 1:
The perfluorinated polyether forms a protective cover layer on the solder bath surface, acting as an intermediary barrier between the molten solder and atmospheric oxygen. This layer prevents oxidation reactions without requiring complex mechanical or atmospheric control systems, maintaining system simplicity while providing effective oxidation protection.
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
Significantly increases the intervals between solder bath changes by effectively binding and removing lead-containing impurities, improving solder quality and reducing environmental risks while minimizing material and operational costs.
Implementation Method 1
uses perfluoric polyether for reaction with impurities containing lead
Implementation Method 2
reduce the formation of these oxides by applying a cover of an oil or a gas
Data Source
Figure 1~2
Figure 3
AI summary
A method is described for operation of a wave soldering system which has a solder bath (1) filled with a lead-free solder (3), and during operation generates a solder wave (7) with which assemblies (9) passed in sequence over the solder wave (7) are soldered, with which the operating time of the system between two changes of the bath necessitated due to an enrichment of lead-containing impurities in the solder bath (1), can be increased significantly, in which perfluoric polyether (19) is added to the solder of the solder wave (7) flowing back into the solder bath (1), which has a boiling point above the solder temperature of the lead-free solder (3). The perfluoric polyether (19) binds to the solder at least a portion of the lead-containing impurities potentially produced during the soldering process, and the lead-containing impurities tied up in the perfluoric polyether (19) are removed from the solder bath (1), in that an upper layer of the solder bath containing the perfluoric polyether (19) with the lead-containing impurities tied up therein, is skimmed off.