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Optical Clear Adhesive (OCA)

Optically Clear Adhesive (OCA) is a transparent adhesive film used to bond optical/display layers while keeping high light transmission and low haze. It is commonly used in:

  • Smartphone and tablet touch screens

  • LCD/OLED display modules

  • Cover glass bonding

  • Touch sensor bonding

  • Polarizer/display bonding

  • Automotive displays

  • Flexible displays

  • Optical films and lenses

 

What OCA does

OCA fills the air gap between two optical surfaces, such as cover glass + touch panel or touch panel + LCD/OLED. Replacing air with adhesive improves optical performance because it reduces reflection at interfaces. The main benefits:

  • Higher brightness and contrast

  • Lower reflection

  • Better sunlight readability

  • Stronger mechanical bonding

  • Better touch sensitivity

  • Improved impact resistance

  • Reduced dust and moisture intrusion

 

Common OCA materials

The most common OCA chemistries are:

      Type - Features - Applications

  • Acrylic OCA: High clarity, good adhesion, cost-effective; Smartphones, tablets, LCD/OLED.

  • Silicone OCA: Flexible, high temperature resistance, good reworkability; Flexible displays, automotive.

  • PU / Urethane OCA: Soft, impact resistant, good stress relaxation; Curved displays, cover glass bonding.

  • UV-curable OCA / LOCA: Liquid before curing, good gap filling; Optical bonding, repair, irregular surfaces.

 

Typical OCA film structure

Most dry OCA comes as a three-layer film: Release liner, OCA adhesive layer, Release liner. During use, one liner is peeled off, the OCA is laminated to the first surface, then the second liner is removed and the second surface is bonded.

 

Important OCA properties

For display applications, key specifications include:

      Property: Typical requirement

  • Light transmittance> 90%

  • Haze: Very low, often < 1%

  • Refractive index: Around 1.47–1.52

  • Thickness: Commonly 25–250 μm

  • Yellowing resistance: Very important

  • Bubble resistance: Critical

  • Adhesion strength: Must match glass, PET, ITO, polarizer, etc.

  • Dielectric property: Important for touch panels

  • Reliability: Heat, humidity, UV, thermal cycling

 

OCA vs LOCA

      Item: OCA - LOCA

  • Form: Dry adhesive film - Liquid adhesive

  • Process: Lamination - Dispensing + UV curing

  • Thickness: control Excellent - More difficult

  • Bubble control: Requires vacuum lamination - Requires careful dispensing/curing

  • Rework: Sometimes easier - Can be harder

  • Best for: Flat displays, high-volume production - Irregular gaps, repair, curved surfaces

 

Basic OCA fabrication concept

The biggest manufacturing challenges are dust, bubbles, thickness uniformity, residual solvent, yellowing, and adhesion balance. OCA is usually made by:

  1. Formulating an optically clear adhesive resin

  2. Mixing additives and degassing

  3. Coating adhesive onto a release liner

  4. Drying or UV/thermal curing

  5. Laminating a second release liner

  6. Slitting, die-cutting, and packaging in cleanroom conditions

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Major OCA Manufacturers

Some well-known companies include:

 

Useful company websites:

How to fabricate OCA

OCA is usually fabricated as a dry, optically clear PSA film sandwiched between two release liners. Basic fabrication flow:

  1. Select resin system
    Common choices:
    acrylic PSA for display/touch panels, silicone OCA for high temperature or flexible displays, or PU/urethane acrylic hybrids for toughness. OCAs are typically acrylic or silicone pressure-sensitive adhesives made into transfer films between release liners.

  2. Formulate adhesive
    Typical ingredients:
    adhesive polymer or oligomer, photoinitiator or thermal initiator, crosslinker, tackifier if needed, UV absorber/HALS stabilizer, defoamer, adhesion promoter, and sometimes refractive-index modifiers.

  3. Mix and degas
    Mix under clean conditions, then vacuum-degas to remove bubbles. Filtration is important, often sub-micron to a few microns, depending on optical quality target.

  4. Coat onto release liner
    Use slot-die, comma-roll, knife-over-roll, or microgravure coating. Common OCA thicknesses are about 25–250 μm, depending on cover glass gap, display type, and step height.

  5. Dry or partially cure
    1). For solvent acrylic OCA: oven-dry to remove solvent.
    2). For UV-curable OCA: UV expose to build molecular weight/crosslink density.
    3). Goal: clear, bubble-free, uniform film with controlled tack.

  6. Laminate second liner
    Laminate a second PET/silicone release liner on top to make a transfer adhesive film.

  7. Slit, sheet, die-cut
    Convert the roll into sheets or die-cut shapes in a cleanroom.

  8. Use in display lamination
    Peel one liner, laminate to glass/polarizer/touch sensor, peel second liner, then bond to the next layer using vacuum lamination/autoclave to remove bubbles.

 

Key target properties

Good OCA generally needs high transmittance, low haze, refractive index close to glass/plastic, stable adhesion, low yellowing, and good humidity/thermal reliability. Typical published targets are very low haze, high transmission, and refractive index around 1.48–1.52 for glass matching.

 

Main process controls

Control these carefully: Dust, bubbles, coating thickness, residual solvent, yellowing, liner release force, gel particles, moisture, and shrinkage. For display-grade OCA, fabrication should be done in a cleanroom, because even tiny particles can create bubbles, mura, or optical defects.

How to increase OCA viscosity

To increase the viscosity of an optically clear adhesive (OCA), you can evaporate solvents from liquid adhesives, use temperature control, add nano-fillers like fumed silica, or adjust the formulation with higher-molecular-weight polymers. Because OCAs require absolute transparency, you must avoid adding anything that introduces haze or refractive index mismatches.

​

To increase viscosity of optically clear adhesive (OCA), use these levers:

​

1. Increase polymer/oligomer molecular weight

  • Pre-polymerize acrylic monomers longer before final coating.

  • Higher MW gives higher syrup viscosity, often best for maintaining clarity.

 

2. Raise solids content / reduce solvent

  • For solvent-based OCA, reduce solvent or use higher-resin-content formulation.

  • Watch coating defects and bubble release.

 

3. Add transparent rheology modifier

  • Use nano silica / surface-treated fumed silica at low loading.

  • Must be well-dispersed; agglomerates cause haze. Fumed silica is widely used to increase thixotropy/viscosity in adhesives.

 

4. Use higher-viscosity monomers or oligomers

  • Replace part of low-viscosity diluent monomer with urethane acrylate, high-MW acrylic oligomer, or silicone/urethane-based resin.

  • Avoid too much multifunctional monomer, which can make OCA too hard.

 

5. Slightly increase crosslinker

  • Helps gel strength and anti-flow after coating.

  • Too much crosslinking can increase modulus, reduce tack, and create haze or stress.

 

6. Lower processing temperature

  • Viscosity rises at lower temperature.

  • Useful for coating control, but may worsen leveling and bubble release.

 

7. Add compatible tackifier or resin

  • Can increase viscosity and adhesion.

  • Must match refractive index and be non-yellowing.

 

For OCA, the safest starting approach is usually: increase acrylic prepolymer molecular weight first, then fine-tune with very low-loading surface-treated nanosilica only if more thixotropy is needed. Optical clarity is critical; OCAs often target very high light transmission and low haze.

​

Dichroic Dye Suppliers

“Dichroic dyes” are most commonly used in guest-host LCDs, smart windows, optical filters, security inks, and polarization-dependent optical applications. Here are several well-known suppliers and manufacturers in this field:

 

Dichroic Dye / Guest-Host LCD Material Suppliers

  • Mitsui Chemicals / Hodogaya Chemical — Known for liquid crystal display materials and dichroic dyes for guest-host LCD applications.

  • Yamamoto Chemicals Inc. — Specialty dichroic dyes and LCD optical materials.

  • Merck KGaA (EMD Electronics) — Major supplier of liquid crystal and display materials, including specialty optical dyes.

  • DIC Corporation — Functional dyes, pigments, and optical materials.

  • NJC Corporation — Optical and electronic materials including LCD dye systems.

  • Hayashibara Co., Ltd. — Functional color materials and specialty chemicals.

 

Suppliers for Dichroic Coatings / Dichroic Glass (Related but Different)

If you actually mean “dichroic” optical coating materials rather than LCD dyes:

  • CBS Dichroic Glass — Major producer of dichroic-coated glass and optical color materials.

  • Edmund Optics — Dichroic optical filters and mirrors.

  • Thorlabs — Dichroic filters, beam splitters, and photonics optics.

  • Omega Optical — Custom dichroic filters and fluorescence optics.

  • SCHOTT — Advanced optical glass and coatings.

 

China-Based Sources

  • Shenzhen Santech — Guest-host LCD and smart-glass materials.

  • BOE Technology Group — Display technologies and advanced optical materials.

  • Shanghai Keyan Phosphor Technology — Specialty optical and display chemicals.

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Dichroic dye-In-OCA

Dichroic dye-in-OCA is possible, but it is usually not as simple as mixing dichroic dye directly into ordinary OCA.

Dichroic dyes need molecular orientation to create useful polarization-dependent absorption. If the dye is randomly dispersed in OCA, the film may only act like a tinted adhesive, not a strong dichroic/polarizing layer. In current technical literature, the more practical structure is often:

 

Dichroic dye-doped LC polymer film + OCA lamination

 

A 2023 ACS paper describes a dichroic dye-doped hybrid-aligned liquid crystal polymer film transferred onto optical clear adhesive / OCA, forming a DD-HLCP/OCA optical film.

 

Practical material stack

Typical structure:

  • Release liner

  • OCA layer

  • Dichroic dye-doped aligned LC polymer or PVA polarizing layer

  • OCA / PSA layer

  • Release liner or optical substrate

​

For a switchable version:

  • Glass / ITO

  • Alignment layer

  • LC host + dichroic dye

  • Spacer

  • ITO / glass

  • OCA lamination to cover lens or display

​

Guest-host LC systems use a liquid crystal host plus dichroic dye guest; the dye aligns with the liquid crystal molecules and changes absorption depending on orientation.

 

Potential suppliers to contact

      Dichroic dye supplier - Why relevant

  • Mitsui Fine Chemicals: States it is one of the world’s leading dichroic dye manufacturers, mainly for LCD and automotive display use.

  • Yamamoto Chemicals: Offers dichroic dyes for liquid crystal displays; notes good solubility in liquid crystal, contrast ratio, and clarity.

  • Nagase ChemteX: Lists dichroic dyes for liquid-crystal light-control devices and polarization devices.

  • Merck / EMD Electronics: Strong LC host-material supplier; useful if your design is guest-host LC rather than passive OCA film.

 

      OCA / LOCA suppliers - Notes

  • 3M: Major OCA supplier; 3M says it has more than 120 OCA options for consumer, vehicle, industrial, and foldable OLED display applications.

  • Adhesives Research / ARclear: Supplies ARclear OCA tapes for display bonding.

  • Henkel: Supplies liquid optically clear adhesives for display and touch-panel bonding.

  • tesa: Supplies optically clear tapes for modern displays and HMIs.

  • Opteria: Offers OCA sheets for direct bonding and bonding optical films.

 

Key design cautions

For direct dye-in-OCA, check these before development:

  1. Dye orientation — OCA alone usually does not align dichroic dyes well.

  2. Solubility — many dichroic dyes are designed for LC hosts, not acrylic/silicone OCA.

  3. Haze — dye aggregation can increase haze and reduce display clarity.

  4. UV and heat stability — display OCA may see UV, 85°C/85% RH, thermal cycling.

  5. Adhesion loss — dye additives may poison acrylic PSA chemistry.

  6. Color shift — dye spectrum can change after UV curing or aging.

  7. Polarization efficiency — define target dichroic ratio, transmittance, haze, and extinction ratio.

 

Best supplier approach

Ask for one of these, depending on your product goal:

  • For passive privacy / viewing-angle film: Ask for a dichroic dye-doped aligned LC polymer film laminated with OCA, not simply “dye in OCA.”

  • For switchable smart window / dimming film: Ask for a guest-host LC mixture with dichroic dye, then use OCA only for lamination to glass or display.

  • For color-shifting decorative film: You may not need dichroic dye; you may need dichroic interference film or multilayer optical film with clear PSA instead. 3M dichroic glass finishes, for example, use a clear pressure-sensitive adhesive and color-shifting film structure.

 

A good RFQ phrase would be:

We are looking for a custom optical film: dichroic dye-doped aligned LC polymer or dye polarizer laminated with optically clear adhesive, target haze <1%, high transmittance, display-grade reliability, and optional roll-to-roll format. Please advise available dye colors, dichroic ratio, OCA thickness, substrate, and 85/85 reliability data.

85°C/85% RH Test

The "85/85" test (or "double 85" test) is an industry-standard accelerated life and environmental reliability test. It exposes products to 85°C/85% RH for extended periods to simulate harsh, long-term tropical or real-world degradation. 

 

Test Parameters & Standardization

  • Conditions: Constant 85°C (+/- 2°C) and 85% relative humidity (+/- 3%).

  • Duration: Typically runs continuously for up to 1,000 hours (roughly 41.5 days).

  • Acceleration Factor: 1,000 hours at 85/85 usually correlates to multiple years of standard outdoor or tropical exposure, accelerating moisture-driven failures like corrosion and delamination.

  • Standards: Defined by bodies like JEDEC (e.g., JESD22-A101), IEC, and various automotive and photovoltaic specifications. 

 

Industries & Applications

The 85/85 test is the cornerstone of moisture reliability qualification across multiple sectors: 

  • Semiconductors & Electronics: Evaluates corrosion, metal migration, and package cracking in microchips, PCBs, and smartphones.

  • Solar/Photovoltaics: Validates the long-term weather resistance and moisture ingress of PV panels.

  • Automotive: Assures that under-the-hood and in-cabin electronics survive extreme, humid climates.

  • Material Science: Tests adhesives, coatings, and film capacitors for hydrolytic breakdown and bond failure. 

 

Typical Failure Mechanisms

During the test, moisture and high heat drive several common failure modes: 

  • Corrosion: Accelerated oxidation of conductive traces or wire bonds (e.g., copper vs. silver degradation).

  • Delamination: Loss of adhesion between dissimilar materials (e.g., printed electronics, epoxies) due to moisture swelling.

  • Electrical Drift: Changes in parasitic capacitance or leakage currents caused by moisture absorbing into plastic packaging. 

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