Henkel LOCTITE 3705 UV Cure PCB Edgebond Adhesive for Electronic Components

LOCTITE 3705 UV Cure PCB Edgebond Adhesive Performance

LOCTITE 3705 cures when exposed to UV or visible light of sufficient intensity. Henkel’s reference process uses 365 nm ultraviolet light at 30 mW/cm² for approximately 80 seconds. Under a separate fixture-time test on glass slides, the adhesive reaches the defined fixture strength in no more than ten seconds at 6 mW/cm² measured at 365 nm. Actual cure speed and depth depend on lamp spectrum, intensity, exposure time, distance, bond-line thickness, and substrate light transmission.

The uncured adhesive has a typical Brookfield viscosity of approximately 44,000 mPa·s at 25°C and a specific gravity of about 1.1. This paste consistency supports controlled dots, beads, and edge fillets. Because no thermal post-cure is required under the recommended light-curing process, manufacturers can shorten production cycles and reduce additional heating steps for temperature-sensitive assemblies.

PCB Component Reinforcement and Edgebond Applications

The product is intended for reinforcing electronic components mounted on a PCB, where additional reinforcement against handling and mechanical stress is required. Typical uses include selected integrated circuits, connectors, modules, and other components with light-exposed fillets. Process engineers should verify compatibility with solder masks, component bodies, coatings, plastics, and cleaning residues before production approval.

Published cured properties include tensile strength of approximately 15.6 MPa, elongation of about 186%, tensile modulus of 175 MPa, and thermal conductivity of approximately 0.17 W/m·K. Henkel also reports polycarbonate-to-polycarbonate block shear strength of approximately 12.56 MPa under the specified laboratory method. These reference values should be confirmed in the actual joint design.

7 Benefits of LOCTITE 3705 UV Cure PCB Edgebond Adhesive

• Fast light curing: Supports rapid electronic assembly and short production cycles.
• One-component processing: Requires no weighing, ratio control, or mixing.
• Thixotropic consistency: Reduces migration after dispensing around component edges.
• No post-cure requirement: Eliminates an additional thermal curing stage.
• Good substrate adhesion: Bonds a variety of compatible electronic materials.
• Controlled dispensing: Medium viscosity supports beads, dots, and reinforcing fillets.
• Electrical properties: Provides high volume and surface resistivity after curing.

Application and Light-Curing Guidance

Ensure all bonding surfaces are clean and free from grease, dust, moisture, flux, and other contamination. Protect uncured product from daylight, UV light, and strong artificial lighting. Use black or fully light-blocking feed lines and reservoirs. Apply the adhesive to one bonding surface, assemble immediately, and expose the complete adhesive area to a validated light source.

Provide cooling when curing near heat-sensitive thermoplastics. Crystalline and semi-crystalline plastics should be checked for stress cracking before use. Remove excess uncured adhesive with a compatible organic solvent, then allow the assembly to cool before applying service loads. Store unopened containers in a dry, light-protected location according to the current package label and safety documentation.

Official Resources and Related Electronic Adhesives

Review the official LOCTITE 3705 technical data sheet and Henkel electronics adhesive solutions for current technical, processing, storage, and safety information.

Explore our UV-curable electronic adhesives for additional rapid bonding and component reinforcement products. Browse our PCB assembly adhesives for edgebonding, staking, wire securing, coating, and module assembly. Contact our sales team for quotations, availability, curing guidance, documents, and export support.