Glycolic Acid Vapor Reducing Atmosphere for Solder Oxide Removal
Solution Overview
Problem
Conventional soldering methods in microelectronics and optoelectronics face challenges with flux residues causing reliability issues and contamination, and existing fluxless solutions like forming gas are insufficient for oxide removal and are either corrosive or require high temperatures, while formic acid vapor is toxic and requires a closed environment.
Innovation Solution
A method and apparatus using glycolic acid vapor as a reducing agent to create a reductive atmosphere for soldering, which is introduced into a processing chamber with a heater to process electronic devices at temperatures between 250°C to 500°C, effectively removing oxides without the drawbacks of formic acid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If forming gas is used as reducing agent, then the process is convenient and clean, but it is insufficiently effective to remove oxide and prevent solder from re-oxidizing
Solution Approach 1:
The patent changes the chemical composition parameter of the reducing atmosphere from conventional forming gas (N2/H2) to glycolic acid vapor. This parameter change enables effective oxide removal at lower temperatures (above 100°C) while maintaining process convenience and cleanliness, resolving the contradiction between ease of operation and reliability of oxide removal.
2Reliability
If formic acid vapor is used as reducing agent, then it is effective for oxide removal, but it has strong corrosiveness, pungent odor and toxicity requiring closed environment and complex handling
Solution Approach 1:
The patent uses glycolic acid vapor as a replaceable reducing agent that can be supplied in controlled amounts and then exhausted. This approach allows effective oxide removal while avoiding the accumulation of toxic residues, reducing handling complexity compared to formic acid that requires closed environments and complex residue management.
Solution Approach 2:
The patent introduces an intermediary substance (glycolic acid vapor) that mediates between the soldering process and the oxide removal function. This intermediary provides effective reduction while being safer and easier to handle than formic acid, reducing the complexity of equipment and handling procedures.
3Temperature
If forming gas is used, then it can be used at lower temperatures, but high H2/H2O pressure ratios or long reaction times are needed for deoxidization
Solution Approach 1:
The patent changes the chemical nature of the reducing atmosphere from hydrogen-based to glycolic acid-based. This parameter change enables effective oxide removal at lower temperatures with shorter reaction times, as glycolic acid vapor actively reacts with oxides at temperatures above 100°C without requiring long exposure times or high pressure ratios.
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 use of glycolic acid vapor enhances solder wetting ability, improves die bond quality, reduces voids and die tilting, and is safer and more cost-effective than existing solutions, making it a suitable replacement for forming gas and formic acid vapor.
Implementation Method 1
creating a reductive atmosphere in the chamber by supplying a gas comprising glycolic acid vapor
Implementation Method 2
supplying a gas comprising glycolic acid vapor
Implementation Method 3
heating the electronic device to a processing temperature with a heater
Implementation Method 4
Glycolic acid vapor enhances solder wetting ability, improves bond quality
Data Source
AI summary
A manufacturing process and apparatus therefore are provided for processing an electronic device comprising oxidizable material during processing. The electronic device is located inside a chamber and is heated a processing temperature with a heater. A reductive atmosphere is created in the chamber by supplying a gas comprising glycolic acid vapor while processing the electronic device at the processing temperature.