LOCTITE AA 3103 Light Cure Adhesive for Polycarbonate Plastic Metal and Glass Bonding

LOCTITE AA 3103 Light Cure Adhesive for Stress-Sensitive Plastics

LOCTITE AA 3103 Light Cure Adhesive is a one-component, medium-viscosity acrylic adhesive developed for fast and flexible bonding of stress-sensitive plastics. Formerly known as LOCTITE 3103, the acrylated-urethane formulation is primarily designed for bonding polycarbonate to itself without inducing stress cracking under typical molded-stress levels. It also provides excellent adhesion to many other plastics, metals, glass, and ceramic materials.

The transparent to slightly hazy adhesive cures rapidly when exposed to ultraviolet or visible light of sufficient intensity. Because no resin-to-hardener measuring or mixing is required, the product supports automated dispensing, short production cycles, and consistent application. Its thixotropic characteristics reduce unwanted migration after dispensing, helping the adhesive remain around edges, gaps, and accurately positioned components.

Key Benefits of LOCTITE AA 3103 Light Cure Adhesive

LOCTITE AA 3103 Light Cure Adhesive has a typical Brookfield viscosity of approximately 8,000–14,500 mPa·s at 25°C, a specific gravity of 1.13, and an uncured refractive index of approximately 1.48. The controlled-flow consistency is suitable for precise beads and dots while still providing effective wetting of properly prepared bonding surfaces.

Curing speed depends on lamp type, irradiance, wavelength, exposure time, bond-line gap, and the light transmission of the substrate. On polycarbonate, fixture time is typically five to ten seconds at 30 mW/cm² measured at 365 nm. Fixture times below five seconds have been reported at 50 mW/cm² with suitable electrodeless lamps. Henkel’s current product page lists a general fixture time of approximately 12 seconds.

The adhesive can achieve a curing depth greater than 13 mm when exposed to suitable light at 50–100 mW/cm² for approximately 30–60 seconds. This depth capability enables applications beyond extremely thin bond lines, although actual curing must be confirmed with the intended component geometry, adhesive volume, lamp spectrum, and production distance.

After curing, the adhesive forms a flexible bond with a typical Shore D hardness of 51, tensile strength of approximately 17 MPa, elongation at break of around 260%, and tensile modulus of about 207 MPa. This combination helps the joint absorb shock and distribute load without creating the high localized stress associated with very rigid adhesives. Typical lap-shear strength on polycarbonate is approximately 11 MPa under Henkel’s specified test conditions.

Applications for LOCTITE AA 3103 Light Cure Adhesive

LOCTITE AA 3103 Light Cure Adhesive is suitable for polycarbonate housings, transparent covers, display components, lenses, light guides, sensors, medical-device components, electronic assemblies, appliance parts, and precision plastic structures. It can also be evaluated for bonding compatible plastics to metal, glass, or ceramic components. Henkel associates the product with consumer electronics, cameras, sensors, industrial automation, and power applications.

The flexible cured structure makes it useful where bonded plastics experience impact, vibration, thermal expansion, or assembly stress. Henkel lists service capability up to approximately 140°C, although the practical operating range depends on joint load, exposure time, substrate stability, and environmental conditions. Every plastic grade should be tested for stress cracking and adhesion before production approval.

How to Apply LOCTITE AA 3103 Light Cure Adhesive

Before applying LOCTITE AA 3103 Light Cure Adhesive, ensure both surfaces are clean and free from grease, oil, dust, moisture, and release agents. Dispense the product using equipment fitted with black feed lines because the uncured adhesive is light sensitive. Position the components and expose the complete bond line to a validated UV or visible-light source.

Henkel recommends a minimum intensity of approximately 5 mW/cm² at the bond line, with an exposure time four to five times longer than the fixture time measured at the same intensity. Exposed surfaces may require UV intensity around 100 mW/cm² to obtain a dry surface cure. Cooling should be provided when processing temperature-sensitive thermoplastics.

Storage of LOCTITE AA 3103 Light Cure Adhesive

Store LOCTITE AA 3103 Light Cure Adhesive unopened in a dry location between approximately 8°C and 21°C. Storage below 8°C or above 28°C may adversely affect product properties. Protect the container from daylight, artificial light, and UV radiation, and do not return dispensed material to its original package.

For manufacturers requiring rapid curing, flexible adhesion, and reliable bonding of polycarbonate and other sensitive substrates, LOCTITE AA 3103 Light Cure Adhesive provides a practical solution for transparent plastics, metals, glass, ceramics, and precision industrial components. Explore our light curing adhesives for polycarbonate, glass, metal, ceramic, electronics, sensors, and precision plastic assembly.

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