Electron Attachment Fluxless Soldering Oxide Removal
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for fluxless soldering, such as using pure hydrogen or organic fluxes, face challenges like flammability, void formation, and environmental concerns, while existing plasma-based techniques are costly and inefficient, requiring vacuum conditions and high temperatures.
Innovation Solution
A method involving a substrate with a base electrode and an energizing electrode with an array of protruding conductive tips, where a gas mixture with a reducing gas is passed through, generating negatively charged reducing gas to reduce metal oxides at relatively low temperatures under ambient pressure, without the need for fluxes or expensive equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pure hydrogen is used for fluxless soldering at high temperature, then solder oxide removal is effective, but the process becomes unsafe due to flammability
Solution Approach 1:
The invention changes the temperature parameter from high temperature (400-450°C) to low temperature (room temperature or slightly elevated), and changes the hydrogen concentration parameter from high (pure hydrogen) to low (trace amounts in inert gas), thereby maintaining oxide removal effectiveness while eliminating flammability hazards
Solution Approach 2:
The invention introduces an inert gas (nitrogen or helium) as an intermediary carrier gas that safely transports trace hydrogen to the solder surface without creating flammable conditions, acting as a mediator between the reducing agent and the solder
2Reliability
If organic fluxes are applied to remove solder oxides, then oxide removal is effective, but voids form in the solder bumps due to flux decomposition
Solution Approach 1:
The invention extracts and eliminates the organic flux component from the process entirely, replacing it with a physical/chemical method using hydrogen ions generated in situ, thereby removing the source of void formation while maintaining oxide removal capability
Solution Approach 2:
The invention substitutes the chemical mechanism of organic flux decomposition with a physical mechanism of hydrogen ion generation and transport, replacing a complex chemical process with a simpler physical process that avoids void formation
3Reliability
If plasma-based techniques are used for fluxless soldering, then oxide removal is effective, but the equipment cost and operational complexity increase significantly
Solution Approach 1:
The invention replaces expensive, complex plasma generation equipment with simple, inexpensive components such as a hydrogen flow controller and a heating element, using consumable hydrogen gas instead of costly plasma system maintenance
Solution Approach 2:
The invention enables the system to generate its own reactive hydrogen species in situ through simple heating of hydrogen-containing gas, eliminating the need for external plasma generation equipment and making the process self-sufficient
4Reliability
If high temperature processing is used for oxide removal, then reduction effectiveness is improved, but substrate damage and energy consumption increase
Solution Approach 1:
The invention fundamentally changes the temperature parameter from high (400-450°C) to low (room temperature to slightly elevated), and adjusts the hydrogen concentration parameter to trace amounts, achieving oxide removal through enhanced hydrogen availability rather than thermal energy
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
This approach effectively reduces metal oxides on substrates at lower temperatures, avoiding the limitations of traditional methods, and is more cost-effective and environmentally friendly, enabling efficient fluxless reflow of solder bumps while maintaining substrate integrity.
Implementation Method 1
generating electrons and passing them through the gas mixture to attach to at least a portion of the reducing gas, thereby forming a negatively charged reducing gas
Implementation Method 2
contacting the treating surface with the negatively charged reducing gas to reduce the metal oxides on the treating surface of the substrate
Data Source
AI summary
The present invention relates to a method for removing metal oxides from a substrate surface. In one particular embodiment, the method comprises: providing a substrate, a first, and a second electrode that reside within a target area; passing a gas mixture comprising a reducing gas through the target area; supplying an amount of energy to the first and/or the second electrode to generate electrons within the target area wherein at least a portion of the electrons attach to a portion of the reducing gas and form a negatively charged reducing gas; and contacting the substrate with the negatively charged reducing gas to reduce the metal oxides on the surface of the substrate.