Lead-Free Cover Glass Composition for Acid-Resistant Semiconductors
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Solution Overview
Problem
Existing glasses for covering semiconductor elements, such as zinc-based and lead-based glasses, pose environmental hazards, have poor acid resistance, and require high firing temperatures, which can deteriorate semiconductor characteristics.
Innovation Solution
A SiO2-B2O3-Al2O3-ZnO-based glass with regulated SiO2/ZnO molar ratio and added MgO and/or CaO, minimizing lead content and optimizing component ratios to enhance acid resistance and lower firing temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lead-based glass is used for covering semiconductor elements, then workability and chemical durability are improved, but environmental harm increases
Solution Approach 1:
The invention changes the chemical composition parameters by completely eliminating lead oxide (PbO) from the glass system and replacing it with a combination of zinc oxide (ZnO), bismuth oxide (Bi2O3), and other metal oxides. This parameter substitution maintains the chemical durability and workability requirements while eliminating environmental harm associated with lead-based glasses
Solution Approach 2:
The invention creates a composite glass material system comprising multiple oxide components (SiO2, B2O3, ZnO, Bi2O3, Al2O3, CaO, MgO, etc.) that work synergistically to achieve the desired chemical durability and firing characteristics without lead. This composite approach replaces the single lead-based system with a multi-component environmentally friendly alternative
2Object-affected harmful factors
If zinc-based glass is used to reduce environmental impact, then environmental harm decreases, but acid resistance deteriorates
Solution Approach 1:
The invention enhances acid resistance by incorporating multiple acid-resistant oxide components including silicon dioxide (SiO2) at 35-70 mass%, boron oxide (B2O3) at 5-40 mass%, and aluminum oxide (Al2O3) at 5-20 mass%. This composite formulation creates a dense glass matrix that resists acid erosion while maintaining environmental compatibility through lead-free composition
Solution Approach 2:
The invention modifies the chemical composition parameters by optimizing the ratios of acid-resistant oxides (SiO2, B2O3, Al2O3) and adjusting the content of basic oxides (CaO, MgO) to achieve the desired balance between acid resistance and environmental friendliness, eliminating the need for additional protective films
3Reliability
If SiO2 content is increased to improve acid resistance, then acid resistance improves, but firing temperature increases
Solution Approach 1:
The invention optimizes the SiO2 content within the range of 35-70 mass% and balances it with other components including B2O3 (5-40 mass%), ZnO (1-30 mass%), and metal oxides (CaO, MgO, Al2O3) to achieve a eutectic composition that lowers the firing temperature to 850-950°C while maintaining sufficient acid resistance through the combined effect of multiple acid-resistant oxides
4Object-affected harmful factors
If lead component is eliminated to reduce environmental load, then environmental harm decreases, but chemical durability worsens
Solution Approach 1:
The invention substitutes lead oxide with alternative metal oxides including zinc oxide (ZnO) at 1-30 mass%, bismuth oxide (Bi2O3) at 1-20 mass%, and combinations of CaO and MgO that provide similar or superior chemical durability through their ability to form stable glass networks and resist chemical attack, while eliminating environmental toxicity
Data Source
AI summary
The glass for covering a semiconductor element contains: in mol %, as a glass composition, SiO2: 20% to 36%, ZnO: 8% to 40%, B2O3: 10% to 24%, Al2O3: 10% to 20%, and MgO+CaO: 8% to 22%, in which SiO2/ZnO is 0.6 or more and less than 3.3 in terms of a molar ratio, and a lead component is substantially not contained.