Zirconium Oxide Solder Paste for Stable Storage Viscosity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The storage stability of solder paste is compromised due to the reactive nature of the activator in the flux, leading to increased viscosity over time, which affects printing performance on miniaturized electronic components.
Innovation Solution
Incorporating a predetermined amount of zirconium oxide powder into the solder paste to suppress redox and acid-base reactions, maintaining the oxide film on the solder powder and preventing the formation of organic acid Sn salts, thereby stabilizing the viscosity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a highly active activator is used in the flux to remove oxide film and ensure wettability, then the initial printing performance is improved, but the viscosity of the solder paste increases over time during storage
Solution Approach 1:
Zirconium oxide powder is introduced as an intermediary substance that mediates between the highly active activator and the solder powder. It suppresses the direct redox reaction between the activator and solder particles, preventing excessive removal of the oxide film while allowing the activator to maintain its wettability function. This intermediary action stabilizes the paste viscosity during storage.
Solution Approach 2:
Zirconium oxide creates a chemically inert microenvironment around the solder particles, protecting them from direct interaction with the highly active activator. This inert barrier prevents the activator from reducing the oxide film prematurely, thereby maintaining viscosity stability while still allowing necessary chemical reactions during the actual soldering process.
2Manufacturing precision
If the oxide film on solder powder is thinned by redox reaction with the activator to improve wettability, then the initial printing performance is enhanced, but the viscosity increases due to formation of organic acid Sn salts
Solution Approach 1:
The harmful redox reaction between the activator and solder particles is converted into a beneficial process by introducing zirconium oxide. The zirconium oxide preferentially reacts with the activator, converting the harmful direct reaction into a controlled interaction that produces zirconium-based compounds instead of organic acid Sn salts. This eliminates the viscosity-increasing side effect while preserving the wettability enhancement.
3Productivity
If the solder paste is stored for a long time to meet production demands, then the productivity is improved, but the viscosity increases due to continuous reaction between activator and solder particles
Solution Approach 1:
Zirconium oxide is added in advance to the solder paste formulation, performing a preliminary protective action before storage begins. It pre-establishes a protective environment around the solder particles, preventing the gradual viscosity increase that would otherwise occur during long-term storage. This preliminary action enables extended storage periods without compromising paste performance.
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 addition of zirconium oxide effectively maintains the viscosity of the solder paste over time, ensuring consistent printing performance and extending the storage period without altering the flux component.
Implementation Method 1
it was found that the SnO2 film thickness on the surface of the solder powder was reduced by the oxidation-reduction reaction in the solder powder flux
Implementation Method 2
the oxide film becomes thin due to an acid-base reaction with the activator
Data Source
AI summary
Provided is a solder paste which uses a conventional flux, and for which long-term preservation is made possible and an easy preservation method can be realized by suppressing changes in the viscosity of the paste over time. This solder paste is provided with a solder powder, a zirconium oxide powder, and a flux, and changes in the viscosity of the paste over time are suppressed.