DOWSIL™ 3-6265 HP Adhesive

Harmonization Code : 3910.00.00.90 | Silicones in Primary Forms; Others

DOWSIL™ 3-6265 HP Adhesive

Main features

  • One-part
  • Versatile heat cure
  • Non-flowing rheology

Product Description

DOWSIL™ 3-6265 HP Adhesive is a one-part, black, non-flowing adhesive engineered for high tensile strength. It utilizes a heat-cure system that allows for rapid, versatile cure processing controlled by temperature, alongside low void formation after cure for sensitive substrates. Because it is a one-part adhesive, no mixing is required, simplifying automated or manual needle dispensing.

Product Key Features

  • One-Part System - requires no mixing, offering a streamlined application process.
  • Versatile Heat Cure - cure rates are rapidly accelerated with heat, achieving cure in 10 minutes at 150°C or 25 minutes at 125°C.
  • Non-Flowing Rheology - maintains its position upon dispensing, making it suitable for targeted placement.
  • Robust Mechanical Profile - cures to deliver a Shore A hardness of 68, a tensile strength of 5.8 MPa (850 psi), and 275% elongation.
  • Low Void Formation - minimizes voiding after cure, enhancing reliability for sensitive electronic assemblies.

Applications

This adhesive is designed to provide unprimed adhesion to many reactive metals, ceramics, and glass, making it highly effective for reliable component sealing and bonding.

  • Electronic Control Units: Used for sealing engine controllers, ABS, and transmission controllers.
  • Component Assembly: Ideal for sealing lids and housings, attaching baseplates, and general gasketing.
  • Power & Connections: Suitable for connector sealing and power supply applications.
Product Family

DS-36265HP

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TDS, SDS & Technical Documents
  • 11-3098-01-dowsil-3-6265-hp-adhesive
    English (Technical Data Sheet (TDS))
  • DOWSIL™ 3-6265 HP Adhesive-Safety Data Sheet-EN
    English (Safety Data Sheet (SDS))

Technical Specifications

General Properties
Color Color
Black
Specific Gravity Specific Gravity
1.33
Physical Properties
Viscosity Viscosity
1,070,000 mPa.s
Mechanical Properties
Elongation Elongation
275 %
Electrical Properties
Dielectric Strength Dielectric Strength
24 kV/mm
Volume Resistivity Volume Resistivity
1.0 E+15 Ohms⋅cm

Additional Information

One-Part High Tensile Strength Silicone Adhesive

DOWSIL™ 3-6265 HP Adhesive

DOWSIL™ 3-6265 HP Adhesive is a premium, one-part, black, non-flowing addition-cure silicone adhesive engineered for high-performance industrial sealing and structural bonding. This heat-activated system requires no material pre-mixing, offering rapid and versatile cure processing controlled entirely by temperature. Formulated with advanced low-void technology, it delivers exceptional tensile strength and superior electrical insulation stability, enhancing the reliability and service life of highly sensitive electronic and PCB system assemblies under challenging service stress.

One-part addition cure 10 min cure at 150°C Non-flowing thixotropic paste 850 psi high tensile strength
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Typical engineering values only. Cure schedules are rapidly accelerated by applying elevated thermal profiles.

DOWSIL 3-6265 HP Adhesive product package
DOWSIL™ 3-6265 HP Adhesive

Key Features

  • One-part system requires no mixing equipment or volumetric tracking, eliminating cross-contamination and waste.
  • Non-flowing thixotropic paste consistency resists running and slumping on perpendicular or overhead joints.
  • Advanced addition-cure formulation generates zero volatile by-products during the complete cross-linking cycle.
  • Deep-section and fully confined cures proceed evenly throughout the mass to enable total process consistency.
  • Engineered low-void technology minimizes micro-void formation to safeguard fragile structural substrates.
  • Outstanding unprimed adhesion profiles to common reactive metals, specialized ceramics, laminates, and glass.

Processing Summary

Cure Schedule Windows: Curing parameters track at 240 minutes at 100°C, 50 minutes at 120°C, 25 minutes at 125°C, or a rapid 10 minutes when processing at 150°C.
Void Reduction Optimization: For heavy cross-sections or if processing voids occur, implementing a 30-minute pre-cure bake cycle at 70°C (158°F) will drastically optimize and reduce void percentages.
Dispense Metrics: Formulated for automated or manual single-needle tip dispensing equipment, exhibiting a reliable baseline extrusion rate profile of 161 g/minute.
Long Production Stability: Addition-curing chemistry provides exceptionally long working and open times under ambient plant conditions, reducing scrap rates and maximizing manufacturing flexibility.
Handling and Application Guidance

Process Notes 

Storage and Material Handling
  • Keep in cold storage at all times in tightly sealed original containers to extend shelf life.
  • Upon standing for several weeks, some filler settling can occur at the base of containers.
  • Thoroughly mix the compound to uniformity prior to industrial application.
  • Verify explicit batch temperature constraints and expiration fields tracked on the product label.
Surface Preparation
  • Clean joint faces using Dow OS fluids, naphtha, mineral spirits, or methyl ethyl ketone (MEK).
  • Avoid using acetone or isopropyl alcohol (IPA) alone, as they do not remove heavy oils well.
  • Execute fine mechanical abrasion to boost bond surface area and maximize clean contact.
  • Employ chemical etching or plasma treatments on non-reactive lines like Teflon, PE, or PP.
Cure Inhibition & De-Airing
  • Avoid contact with organotin catalysts, sulfur, polysulfides, polysulfones, or flux residues.
  • Uncured liquid or tacky material at the substrate boundary layer indicates chemical inhibition.
  • Execute vacuum de-airing profiles at >28 inches Hg for 10 minutes if air extraction is needed.
  • Automated airless needle dispense machinery can bypass the need for separate vacuum cycles.
Typical Properties

Engineering Data for DOWSIL™ 3-6265 HP

Physical & Cured Mechanical Properties

Physical Property Typical Engineering Value Standard / Condition
Appearance / Color Non-flowing paste / Black -
Viscosity 10,700 Poise (1,070 Pa.s) Viscometer
Specific Gravity (Cured) 1.33 ASTM D0792 / CTM 0022
Durometer Hardness 68 Shore A ASTM 2240
Tensile Strength 850 psi (5.8 MPa / 59 kg/cm²) HASTM D412 / CTM 0137A
Elongation at Break 275 % ASTM D412 / CTM 0137A
Tear Strength (Die B) 80 ppi (54 N/cm) -
Linear CTE by TMA 215 ppm/°C -
Unprimed Adhesion (Lap Shear) 825 psi (5.7 MPa / 568 N/cm²) Aluminum

Electrical Performance Properties

Electrical Insulating Parameter Typical Engineering Value Test Condition Spec
Dielectric Strength 550 volts/mil (24 kV/mm) -
Volume Resistivity 1.0 E+15 Ohm-cm -
Dielectric Constant at 100 Hz / 100 kHz 3.20 / 3.15 -
Dissipation Factor at 100 Hz / 100 kHz 0.0036 / <0.003 -
Operational Temperature Capabilities: Cured silicone elastomers retain physical and insulating parameters over an extended continuous service range from -45°C to 200°C (-49°F to 392°F). Under thermal cycling, low-temperature performance limits down to -55°C (-67°F) can be verified depending on part configuration.
Applications

Where DOWSIL™ 3-6265 HP Fits


Automotive Modules
Perfectly configured across demanding automotive sub-assemblies where thermal shifting and robust structural joints are critical.
  • Sealing engine controllers and transmission modules.
  • Ideal structural adhesive for complex ABS units.
  • Resists continuous under-hood vibration and temperature cycles.

Lids, Housings & Power Supplies
Provides a moisture-tight, high-strength structural seal for protective enclosures containing high-voltage power components.
  • Sealing industrial lids, protective housings, and casings.
  • Structural mounting and attaching of heavy baseplates.
  • Maintains high dielectric insulation shielding values.
connector
Connectors & Formed Gaskets
Acts as a durable, non-slumping Formed-in-Place Gasket material to seal wire leads and terminal connections against environmental elements.
  • High-reliability precision electrical connector sealing.
  • Forms tough Formed-in-Place structural gaskets.
  • Intended to successfully survive splash or intermittent solvent exposure.
Product Demo

See One-Part Heat-Cured Silicone Automated Dispensing Methods

Observe the high-precision processing of one-part non-flowing addition-cure silicone compounds utilizing automated needle dispensing machinery. This demonstration emphasizes automated airless line calibration, structural non-sag bead tracking profiles, and in-line oven thermal cure preparation.

Package & Support

Standard Packaging & Technical Help

Standard Container Sizes
  • Multiple packaging sizes are available for this product to accommodate varied production scales.
  • Detailed container and package metrics can be verified directly through your local Dow Sales Office.
  • Original packaging must be kept tightly closed and held in cold storage to extend working shelf life.
Technical Help Capabilities
  • Designing optimized thermal heat cure schedules to balance line performance and processing costs.
  • Evaluating substrate materials and multi-component layouts to prevent addition-cure chemical inhibition.
  • Assisting with automated needle dispense line calibration, matching the specified extrusion rate of 161 g/min.
  • Coordinating small-scale laboratory evaluations to verify maximum cohesive lap shear bond strength.
Technical Guidance

Tips and Troubleshooting

Issue Recommended Action
Voids or bubble formation inside thick cured sections
  • Incorporate a 30-minute thermal pre-cure bake cycle at 70°C (158°F) to dramatically reduce voiding.
  • Utilize a vacuum de-airing schedule of greater than 28 inches Hg for 10 minutes or until bubbling subsides.
  • Implement an automated airless dispense system gear to eliminate the need for independent vacuum cycles.
Adhesive remains liquid or tacky at the interface after heating
  • The addition-cure formulation is experiencing chemical cure inhibition from nearby chemical contaminants.
  • Isolate materials from organotin/organometallic compounds, tin-catalyzed silicone rubbers, and sulfur.
  • Ensure complete removal of polysulfides, polysulfones, unsaturated hydrocarbon plasticizers, and flux residues.
  • Run a small-scale laboratory compatibility test to verify sub-assembly component suitability.
Poor unprimed adhesion or bond line failure on plastics/metals
  • Unprimed bonds will not adhere well to non-reactive surfaces like Teflon, polyethylene, or polypropylene.
  • Thoroughly degrease surfaces using Dow OS fluids, naphtha, or MEK; avoid acetone/IPA for heavy oils.
  • Introduce localized fine mechanical surface abrasion to promote cleaning and increase bonding surface area.
  • Apply specialized surface treatments like chemical etching, plasma exposure, or matching Dow chemical primers.
  • Screen plastic or rubber substrates for mobile plasticizers that can migrate and act as unwanted release agents.
Next Steps

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