Overview

Soda-lime substrates are cost-effective glass wafers made from high-quality soda-lime silicate glass, a material widely used in the optics, electronics, and display industries. Composed primarily of silica (SiO₂), sodium oxide (Na₂O), and calcium oxide (CaO), soda-lime glass offers a well-balanced combination of optical transparency, mechanical strength, and ease of processing.

Due to its affordability and stable physical properties, soda-lime substrates are commonly used for general-purpose optical components, photolithography experiments, coating carriers, and low-temperature semiconductor applications.

Material Properties & Advantages

Soda-lime glass wafers feature practical material properties that make them a popular choice for laboratory and industrial use:

• Excellent Optical Clarity: High transparency (over 90%) in the visible light spectrum (400–800 nm).

• Good Surface Quality: Can be polished to sub-micrometer flatness for precision optical or thin-film applications.

• Mechanical Durability: Moderate hardness and sufficient strength for handling, coating, and bonding.

• Cost-Effective: A budget-friendly substrate alternative compared with fused silica or borosilicate wafers.

• Easy Machining & Coating: Suitable for cutting, drilling, and thin-film deposition such as ITO, SiO₂, or metal layers.

• Smooth Surface & Chemical Compatibility: Compatible with most photoresists, solvents, and coating materials.

Although soda-lime glass has a slightly higher coefficient of thermal expansion (CTE) and lower chemical resistance than borosilicate glass, it remains ideal for low to moderate temperature processes and general optical testing environments.

Manufacturing Process

Soda-lime substrates are produced using float-glass technology followed by precision cutting, lapping, and polishing to achieve semiconductor-grade flatness and clarity.
The typical process includes:

1. Float Glass Formation: Molten glass is floated on a layer of molten tin to produce ultra-flat, uniform sheets.

2. Wafer Cutting: The glass is laser- or diamond-sawn into circular or rectangular substrates.

3. Lapping & Polishing: Both sides are polished to achieve optical-grade smoothness and parallelism.

4. Cleaning & Inspection: Ultrasonic cleaning removes contaminants, ensuring ready-to-use surfaces.

Optional steps include thermal tempering, surface coating, or custom thickness control based on end-user requirements.

Applications

Thanks to their clarity, affordability, and machinability, soda-lime substrates are used in a wide range of optical, electronic, and experimental setups:

• Optical Windows & Filters: Used in lenses, test plates, and optical housings.

• Display & Photonics: Base material for thin-film coatings in display panels and light guides.

• Semiconductor Processes: Serve as temporary carrier wafers or testing substrates.

• Coating & Thin-Film Deposition: Ideal for ITO, SiO₂, and metal film coating for research or prototyping.

• Microscopy & Imaging: Utilized as cover plates, calibration substrates, and micro-scale supports.

• Educational & Laboratory Use: Widely used for optical demonstrations, etching experiments, and photolithography practice.

Technical Specifications

FAQ

Q1: What are the main differences between soda-lime substrates and borosilicate glass wafers?
A: Soda-lime substrates are more economical and suitable for room-temperature or low-thermal applications, while borosilicate wafers provide higher chemical and thermal stability.

Q2: Can soda-lime substrates be used for coating and photolithography?
A: Yes. The polished surface supports photoresist coating, thin-film deposition, and etching processes commonly used in optical and semiconductor labs.

Q3: What temperature range can soda-lime glass withstand?
A: Generally up to 250–300°C without deformation. For higher temperature use, borosilicate or fused silica is recommended.

Q4: Are custom sizes and thicknesses available?
A: Yes, round or square substrates with customized dimensions and thickness tolerances can be supplied upon request.

Q5: Is soda-lime glass suitable for optical measurement applications?
A: Absolutely. With high visible transparency and stable refractive index (~1.52), it’s ideal for optical alignment, calibration, and surface testing.