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Henkel LOCTITE 3128 Low Temperature Cure Epoxy Adhesive for Electronics
Product features
Low-temperature curing at 80°C for 20 minutes ensures good bonding strength.
2. Precise dispensing, capable of meeting the dispensing requirements of 23# and 25# dispensing needles;
3. Low CTE, more precise bonding;
4. There is no glue overflow or displacement during curing.
LOCTITE 3128 Low Temperature Cure Epoxy Adhesive Performance
The uncured material is a black, medium-viscosity epoxy supplied ready for use without resin-and-hardener mixing. Henkel lists a typical specific gravity of 1.6 at 25°C, a yield point of approximately 44,000 mPa·s, and Casson viscosity from 7,000 to 27,000 mPa·s. This rheology supports controlled syringe dispensing and helps the adhesive remain around component edges, narrow joints, and localized reinforcement areas before curing.
Recommended curing conditions are 20 minutes at an 80°C bond-line temperature or 60 minutes at a 60°C bond-line temperature. The heating cycle must include enough time for the adhesive location—not only the oven air—to reach the required temperature. Component mass, fixture design, oven loading, heating rate, and temperature uniformity can change the cure profile, so production settings should be validated with representative assemblies.
Electronic Component Bonding and Reinforcement Applications
LOCTITE 3128 Low Temperature Cure Epoxy Adhesive is particularly suitable for memory cards and CCD/CMOS assemblies. It can also be evaluated for bonding or reinforcing small sensors, imaging modules, connectors, housings, miniature circuit assemblies, and heat-sensitive precision components. Its one-part format simplifies production and eliminates mix-ratio variation, while the black appearance helps operators confirm coverage during dispensing and inspection.
After curing, the epoxy forms a hard structural material with typical Shore D hardness of 88, tensile strength of approximately 35 MPa, and tensile modulus of about 3,900 MPa. Published lap-shear strength is approximately 21 MPa on grit-blasted steel and at least 7 MPa on epoxy-glass under the stated laboratory conditions. Actual performance depends on substrate grade, cleanliness, bond-line thickness, joint design, cure history, and service environment.
7 Benefits of LOCTITE 3128 Low Temperature Cure Epoxy Adhesive
- Low-temperature heat cure: Supports components that cannot tolerate conventional high-temperature epoxy cycles.
- One-component processing: Requires no manual measuring, mixing, or ratio control.
- Fast production options: Offers a reference cure of 20 minutes at 80°C.
- Controlled viscosity: Supports accurate dispensing around small electronic parts.
- Strong structural bonding: Provides high tensile and lap-shear performance after proper curing.
- Electrical insulation: Offers high volume and surface resistivity for evaluated electronics.
- Environmental reliability: Maintains useful strength after specified heat-and-humidity aging tests.
Mechanical, Electrical, and Environmental Properties
Typical cured properties include density of approximately 1.7 g/cm³, volumetric shrinkage of 3.1%, glass-transition temperature of about 45°C, and 24-hour water absorption of 0.17%. The coefficient of thermal expansion is approximately 40 × 10-6/K below Tg and 130 × 10-6/K above Tg. These values help engineers evaluate dimensional change and stress in assemblies exposed to temperature variations.
Published electrical properties include volume resistivity of approximately 2.9 × 1016 ohm-cm and surface resistivity of approximately 2.8 × 1016 ohms. Henkel also reports low outgassing results under the referenced NASA method, including total mass loss of 0.4% and collected volatile condensable material below 0.01%. Final electrical, moisture, and outgassing suitability should be confirmed using the complete production assembly.
Application, Storage, and Official Product Resources
Clean all bonding surfaces and remove oil, dust, moisture, flux residue, release agents, oxidation, and loose contamination. Allow cold-stored material to reach the required dispensing condition according to package instructions while preventing condensation. Dispense the required bead, position the components, and maintain alignment throughout the validated heat-cure cycle. Do not return dispensed or contaminated adhesive to the original syringe.
The published pot life at 25°C is approximately three weeks. Unopened product should be stored dry between -25°C and -15°C, with a stated shelf life of 365 days under specified conditions. Temperatures outside this range may adversely affect product properties, so cold-chain handling and batch traceability are important.
Review the official Henkel LOCTITE 3128 product page and the Henkel-issued LOCTITE 3128 technical data sheet for current properties, cure guidance, storage requirements, and safety information.
Explore our low-temperature cure epoxy adhesives for additional heat-sensitive component bonding products. Browse our electronics structural adhesives for memory cards, sensors, camera modules, circuit assemblies, connectors, and precision devices. Contact our sales team for quotations, 10 ml syringe availability, technical documents, cold-chain shipping, bulk quantities, and export support.
