Custom manufacturing of optical silicone parts for lighting, sensing, and transparent assemblies — supporting LIM molding, PCB overmolding, and optical encapsulation with engineering support from DFM to production.

• High optical clarity & anti-yellowing performance
• Support for lenses, light guides, PCB overmolding and encapsulation
• Tooling, molding, testing and project engineering in one place

Applications

Working on an optical silicone part?
Send us your drawing, application, or performance target. We can help review manufacturability, process route, and tooling direction before quotation.

1. Advantages In Nature

High Optical Clarity — Delivers strong light transmission for lenses, light guides, and optical encapsulation.

Anti-Yellowing & UV Stability — Maintains transparency under long-term light/UV exposure, reducing yellowing and haze over time.

Wide Temperature Tolerance — Performs reliably in high-heat applications and during thermal cycling (e.g., high-power LEDs, automotive lighting).

Excellent Mold Replication — Accurately reproduces complex geometries and micro-features for precise beam shaping and optical consistency.

2. Typical Products

TIR Lenses (Total Internal Reflection Lenses) — Controls beam angle and improves optical efficiency for LED spotlights, downlights, and automotive lighting.

Secondary LED Optics (Collimators / Beam Shaping Lenses) — Shapes and smooths the light output to achieve uniform illumination and reduce glare.

Optical Encapsulation / Potting (LED & Optoelectronic Modules) — Protects chips and sensitive components from moisture, heat, and chemicals while maintaining high transparency.

Light Guides / Light Pipes — Transfers and distributes light to indicators, ambient lighting, and compact assemblies with consistent brightness.

3. Optical Silicone Products Manufacturing

3.1 Liquid Silicone Injection Molding (LIM) — the main production method

Most optical silicone parts are produced by LSR injection molding (LIM), which includes precise metering/mixing, injection filling, and in-mold curing. It enables stable mass production and accurate replication of micro-features.

3.2 PCB overmolding

LIM can also be used for PCB overmolding, molding optical silicone directly onto a PCB to combine optical shaping + sealing/protection in one integrated part.

3.2 Optical Silicone Encapsulation / Chip Encapsulation (High Refractive Index)

This type of optical silicone encapsulation is typically a 2-part (A/B) high-refractive-index silicone designed for LED secondary packaging / SMD chip encapsulation, and it can be mixed with phosphor powder when required. The process starts with accurate ratio mixing (e.g., A:B = 1:10), followed by thorough vacuum degassing to eliminate bubbles for optical clarity. The degassed material is then dispensed onto LED brackets or frames (commonly PPA / PCT / EMC types such as 4014, 3006, 2835, 3030, typically ≤ 1 W). To prevent bubbles caused by moisture, substrates are often pre-baked (e.g., 150°C for 0.5 h) before dispensing. Curing is usually done in stages, such as 80°C for 1 h + 150°C for 3 h (production schedules may be extended for larger batches).

Note: These high refractive index encapsulation grades are often formulated with higher hardness (e.g., Shore D range) for shape retention and optical stability, and the material cost is typically higher than standard silicone potting compounds.

3.3 Additive Dosing & Process Control (Tint, Diffusion, Modifiers)

This is not a standalone process—it’s a formulation and process-control step used during LIM or potting/dispensing. Controlled additives (tint, diffusion agents, UV/heat stabilizers) are added via in-line dosing or pre-mixing to keep optical effects consistent and reduce batch variation (e.g., color shift or uneven diffusion).

4 What Makes Optical Silicone Injection Molding Difficult

Tool polishing & surface quality — Optical cavities often require mirror-level polishing. Minor tool marks, scratches, EDM traces, or imperfect parting lines can appear as haze, glare, or distortion once light passes through the part.

Material characteristics — Optical-grade LSR is formulated for high clarity and low yellowing, and it can be more sensitive to contamination, micro-bubbles, and internal stress. Small variations in mixing, handling, or storage can directly impact transmittance and haze.

Cure behavior and post-curing requirements — Because optical LSR formulations differ from standard LSR, curing behavior may not match typical cycle settings. Some projects require extended curing profiles and even long post-curing (secondary vulcanization) in specialized ovens to achieve optical stability and reduce volatiles or long-term yellowing.

Mold design constraints — Gate type/location, flow balance, venting/vacuum strategy, and runner design are critical. Poor design can lead to weld lines, flow marks, trapped air, or uneven cure—each becoming an optical defect.

Environmental and cleanliness control — Optical parts are highly sensitive to dust and particles. Clean-room or dust-controlled production, disciplined material handling, and strict mold/part protection are often necessary to keep defect rates low.

5. Optical performance & durability testing

5.1 Transmittance & Refractive Index Testing

Instruments: a UV–Vis spectrophotometer (or spectrophotometer with an integrating sphere for total transmittance) for % transmittance vs. wavelength, and an Abbe refractometer or digital refractometer for refractive index (nD).
Method: molded samples are prepared at a controlled thickness (commonly 1–2 mm or as specified by the optical design). Transmittance is measured across the target wavelength range (e.g., visible spectrum), and refractive index is measured at a defined temperature (typically 20–25°C). Results are compared against project specifications and used to confirm optical clarity and design targets.

5.2 UV Aging / Weathering Cycle Testing

Instruments: a UV weathering tester (e.g., UVA/UVB fluorescent UV chamber) or a xenon arc weatherometer to simulate sunlight, often combined with controlled temperature and humidity.
Method: samples undergo repeated exposure cycles (UV irradiation + temperature/humidity steps) for a defined duration (e.g., hundreds to thousands of hours, depending on requirement). After each interval, parts are re-checked for transmittance loss, haze increase, and yellowing—typically using a spectrophotometer and/or haze meter, plus visual inspection for surface defects and discoloration.

6. Our Services

Comprehensive Testing Capability — Equipped for optical and durability verification, including transmittance and refractive index measurement and UV aging / weathering cycle testing, plus appearance and defect inspection aligned with your specifications.

Optical-Grade Materials Supply & Engineering Support — We source optical silicone materials from leading global suppliers such as Shin-Etsu and WACKER, and our in-house material R&D engineers help tailor material selection and processing to meet a wide range of optical silicone product requirements.

LSR Mold Design & Tooling Manufacturing — Full capability from DFM to optical-surface tooling, including gate/vent/vacuum strategy and mirror-finish polishing to support stable clarity and micro-feature replication.

Optical Injection Production Environment — Beyond a standard clean room, we operate a production workshop specifically managed for optical-grade LSR molding, with strict contamination control and handling procedures to reduce bubbles, particles, and surface defects.

Multiple Process Options — We support different manufacturing routes based on your product design and application: standard optical LIM molding, LED PCB overmolding, and optical encapsulation/potting for modules and assemblies.

Complete Processing Equipment — A full set of production equipment for metering/mixing, molding, dispensing, vacuum degassing, curing, and finishing—enabling consistent output from sampling to mass production.