High Purity Stannous Oxide Preparation via Dicarboxylate Complex
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Solution Overview
Problem
Current methods for preparing stannous oxide for electroplating stacked IC chips result in low purity products due to impurities and alpha radiation emissions, which are not suitable for the demanding requirements of modern electronics.
Innovation Solution
A method involving the reaction of a Sn salt with a C2-12 dicarboxylic acid to form a Sn-dicarboxylate complex, followed by washing and reacting with a base to produce high purity stannous oxide with low alpha radiation, avoiding high pH levels and impurities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional methods (reacting stannous salt with alkali hydroxide at high pH) are used to prepare stannous oxide, then the production process is simple, but the product purity is low due to impurity contamination
Solution Approach 1:
The preparation process is divided into multiple sequential steps: (1) reacting stannous salt with dicarboxylic acid to form complex, (2) washing the complex to remove anion impurities, (3) reacting with base to precipitate stannous oxide. This segmentation allows each step to address specific purification needs, achieving high purity through cumulative effect of multiple purification stages.
Solution Approach 2:
The Sn-dicarboxylate complex serves as an intermediary substance that facilitates purification. The complex formation with dicarboxylic acid creates a soluble intermediate that can be washed to remove anion impurities, then decomposed to yield high purity stannous oxide. This intermediary step enables separation of impurities from the desired product.
2Productivity
If alkali carbonate is added to the reaction mixture to yield stannous oxide, then the production is efficient, but foreign cation contamination occurs
Solution Approach 1:
The patent uses volatile base metals (ammonium, alkali, or alkaline earth metals) that serve a temporary function in the reaction and then can be completely removed. These bases are used to precipitate stannous oxide from the washed complex, and their cations are eliminated through washing and drying, leaving no residual contamination in the final product.
Solution Approach 2:
The patent controls pH parameters carefully - maintaining low pH during complex formation and washing, then adjusting to higher pH only during the precipitation step. This parameter control ensures impurity removal at low pH while enabling stannous oxide formation at higher pH, followed by complete removal of base cations through washing.
3Quantity of substance
If high pH levels are used in the reaction, then stannous oxide can be precipitated, but low purity product is obtained due to impurity incorporation
Solution Approach 1:
The patent performs preliminary washing of the Sn-dicarboxylate complex to remove anion impurities before the precipitation step. This preliminary purification action ensures that when stannous oxide is subsequently precipitated at high pH, the impurities have already been removed, preventing their incorporation into the final product and ensuring high purity.
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 method achieves high purity stannous oxide with alpha radiation counts below 0.002 cph/cm², ensuring the product is suitable for electroplating without contamination or quality variations, meeting the stringent requirements of modern electronics.
Implementation Method 1
reacting a Sn salt with a C2-12 dicarboxylic acid in the aqueous phase to form a suspension comprising a Sn-dicarboxylate complex
Implementation Method 2
reacting the washed Sn-dicarboxylate complex with a base to form high purity SnO
Data Source
AI summary
Provided herein are methods for the preparation of high purity stannous oxide comprising: (a) reacting a Sn salt with a C2-12 dicarboxylic acid in the aqueous phase to form a suspension comprising a Sn-dicarboxylate complex; (b) washing the Sn-dicarboxylate complex with water to obtain a wash solution comprising a washed Sn-dicarboxylate complex essentially free of the anion of the Sn salt; and (c) reacting the washed Sn-dicarboxylate complex with a base to form high purity SnO, wherein the high purity SnO has an alpha radiation count of less than about 0.002 cph/cm2.