In practical applications, flame-retardant and heat-insulating capacitive glass touchscreens must balance touch sensitivity, optical performance, high-temperature resistance, flame-retardant safety, and mechanical strength. The following is a detailed solution based on industry best practices:
1. Flame-retardant and heat-insulating design of the glass substrate
The core of a capacitive touchscreen is the glass substrate (Cover Lens + Sensor Glass), which requires optimization in both material and structure:
Flame-retardant glass selection
Chemically strengthened aluminosilicate glass
High temperature resistance (softening point ≥800°C), inherently non-flammable (meets UL94 V0 rating).
The surface can be enhanced with a nano-ceramic coating (e.g., SiO₂ sol-gel) to improve flame retardancy and thermal shock resistance.
Recommended thickness: 0.7–2.0 mm (balancing strength and touch sensitivity).
Laminated flame-retardant glass
Two layers of glass with flame-retardant PVB (polyvinyl butyral) or EVA film sandwiched between them, cured under high temperature and pressure.
Advantages: Even if the glass breaks, the film prevents shards from flying and blocks the spread of flames.
2. High-temperature resistance and flame retardant optimization of touch sensors
The sensor layer (ITO or metal mesh) of capacitive touchscreens must operate stably at high temperatures:
(1) Conductive layer material
Metal mesh (copper/silver nanowires)
More heat-resistant than traditional ITO (silver nanowires can withstand temperatures above 150°C) and more flexible.
Better flame-retardant properties than ITO (no brittleness issues associated with indium tin oxide).
Circuit design: micro-fine mesh (line width <5μm) to reduce visibility.
Graphene conductive film
High-temperature resistant (above 200°C), high transparency (>90%), but higher cost, suitable for high-end applications.
(2) Flame-retardant OCA optical adhesive
Silicone-based OCA
Temperature range -40°C to 200°C, low smoke and non-toxic (complies with UL94 V0).
Replaces traditional acrylic adhesive (which is flammable and prone to yellowing at high temperatures).
Flame-retardant PSA (pressure-sensitive adhesive)
Used for bonding sensors to cover glass, must pass the GB/T 2408 vertical burning test.
3. Overall Encapsulation and Heat Dissipation Design
Edge Sealing and Fire Prevention
High-temperature silicone sealant
Prevents moisture and flames from entering through the edges (e.g., Shin-Etsu KE-45 series silicone).
Metal frame heat dissipation
Aluminum alloy or stainless steel frame design accelerates heat dissipation (requires insulation treatment to prevent touch interference).
4. Challenges and Future Directions
Cost control: Metal mesh/graphene conductive film costs are high, requiring cost reduction through scale.
Transmittance balance: Thermal insulation coatings may reduce transmittance (optimization to ≥88% required).
Flexibility requirements: Flexible flame-retardant glass (e.g., ultra-thin flexible glass UTG) is a research hotspot.