When an electronic assembly fails in service, the root cause is often not the silicon on the pcb but what surrounds it: a seal that lets moisture in, a bond line that cannot tolerate vibration, or a material that does not cope with repeated thermal cycling. That is where aerospace silicones earn their place, bringing sealing, adhesion, stress relief and protection in demanding duty. Dow has been developing silicones for aviation since 1943 and continues to supply silicone material families used across aerospace, defence and avionics applications.
Next, you will find how our silicone product families map to common engineering needs (sealing, bonding, protection, thermal management, emi shielding and optical coupling), plus examples of specific DOWSIL™, SYLGARD™ and SILASTIC™ materials.
Why silicones are chosen for aerospace assemblies
Silicone materials are described as ozone resistant and naturally stable across wide ranges of temperature and moisture, with a useful temperature range from -115°c to 260°c. They are also described as highly stress relieving, with a modulus that commonly ranges from 0.01 to 10 mpa. In practical terms, that combination is valuable wherever dissimilar substrates meet, where vibration is persistent, or where thermal expansion mismatch would otherwise drive fatigue at interfaces.
What stress relieving means in day-to-day design
Stress relief translates into better tolerance of:
- Thermal cycling across assemblies with mixed materials
- Vibration and mechanical shock transferred into joints
- Local strain around sensitive components, connectors and soldered regions
It also supports more robust sealing and bonding strategies where you want a joint to remain compliant rather than becoming brittle over time.
What are exactly silicone solutions?
We organise our solutions into several product families, each aligned to a set of engineering functions:
- Adhesives, sealants and foams: positioned as able to outperform organics under demanding conditions, remain flexible over wide temperature ranges, adhere reliably to a variety of substrates, and support light-weighting and sealing.
- Coatings, gels and encapsulants: positioned for protection against moisture, dirt, shock, vibration and heat fluxes, with stress relief, dimensional stability and minimal shrinkage.
- Liquid silicone rubbers (LSRS): highlighted for ease of processing, good mechanical properties, and resistance to extreme temperatures and ageing.
- Optically clear materials: positioned for high performance under harsh conditions, with solutions that range from dispensable to mouldable, supporting design flexibility for lighting, electronics and displays.
- Thermal interface and electrically conductive materials: positioned for thermal management, gap filling, a choice of thermal conductivities, and emi shielding effectiveness with electrically conductive options.
Across these categories, aerospace silicones are less about a single product type and more about selecting the right silicone format for the job: sealant, adhesive, coating, gel, encapsulant, thermal interface or conductive material.
Where aerospace silicones typically sit in an aircraft or UAV build
Fixed-wing aircraft, rotary-wing aircraft and UAVS need sealing, adhesive bonding, thermal management and protection against electromagnetic interference (EMI). Whether an aircraft is fuel-powered or battery-driven, engineers expect materials to help them solve design challenges while meeting strict safety standards.
Sealing, gasketing and repair support around fuel systems
We supply sealants and foams that are used in interior and exterior applications, and we reference use as gaskets for compressors, gear boxes and pumps. These are areas where vibration, heat and fluid exposure can converge, and where a compliant seal helps protect the system.
Product references for sealing and general bonding
These are several sealants and adhesives commonly considered for aircraft assemblies:
- Dowsil™ 732 multi-purpose sealant: flexible from -60°c to 180°c with short peaks to 205°c, for broad sealing needs.
- Dowsil™ 3145 rtv mil-a-46146 adhesive/sealant: non-flowing with high tensile strength and fast in-line cure, with optional heat acceleration.
- Dowsil™ 7092 high green strength adhesive and sealant: positioned for instant green strength and adhesion to a wide range of substrates.
These examples show how aerospace silicones can be selected not only for end performance, but also for how they behave during assembly.
Solvent and fuel resistance for systems and tanks
We also provide fluorosilicone sealants that are resistant to solvents. Our solvent resistant sealants support assembly and repair of fuel systems and tanks, where chemical exposure is a defining constraint.
Product reference for solvent resistance
- Dowsil™ 730 fs solvent resistant sealant, a stable and flexible fluorosilicone adhesive/sealant from -65°c to 260°c, retaining properties under exposure to fuels, oils and solvents.
Bonding and thermal paths in power and conversion modules
We support advanced silicone use in transmission, power and conversion modules for tasks such as bonding substrates to heat sinks, bonding integrated circuit substrates, attaching heat sinks, and adhering lids, housings and base plates. These are typical interfaces where thermal paths and mechanical compliance must be balanced.
For more-electric aircraft, we also provide thermal-management solutions for batteries and the batteries system. As electrification increases thermal density, aerospace silicones are increasingly part of thermal design choices, not simply assembly aids.
Defence: protection through harsh duty profiles
Dow supports defence applications across air, land and sea missions, where equipment must operate through desert heat, arctic cold and heavy rain. We offer coatings, gels and encapsulants that resist shock and stress while damping vibration and providing flame resistance. It is important to note that many products are mil-spec tested and UL approved.
How our coatings, gels and encapsulants protect electronics
For defence electronics, protection is rarely a single threat. It is usually a combination: moisture, contaminants, mechanical shock, constant vibration and heat flux. Our conformal coatings, gels and encapsulants are positioned to address these combined loads, with material choices that support stress relief and long-term stability.
Conformal coating references
Our product list includes multiple conformal coatings, such as IPC-CC-830 and MIL-I-46058, and several UL 94 classifications across listed coating products.
This is one reason aerospace silicones remain a frequent choice for rugged electronics: compliant protection that is designed around how assemblies actually fail in the field.
Avionics, displays and lighting: optical clarity, thermal management and EMI control
We link avionics and cockpit systems to the need for pilots to see fuel levels, air traffic and flight control data, and we note the growing importance of flight recorders and collision avoidance systems as skies become busier. To support those requirements, we provide rugged solutions for displays and lighting, alongside thermally conductive materials for heat dissipation and electrically conductive materials for emi shielding.
Our optically clear materials for bonding and coupling
We provide optically clear materials that resist temperature and humidity extremes and are used from flight displays to instrument and cabin lighting.
Product references for optical coupling and display bonding
- Dowsil™ EG-1200 gel: highly transparent, rapidly curing, flowable, with high tackiness for coupling a variety of surfaces, and usable as a liquid optically clear coupling agent for displays and lighting.
- Dowsil™ MS-1002 mouldable silicone: optically clear, suitable for producing fine-detail optical parts, with resistance to ageing.
- Dowsil™ VE-XXXX UV: transparent, low modulus and low shrinkage, a uv-curable resin for liquid-based bonding, designed to bond display cover glass/plastic and touch panel to lcd/oled modules.
In avionics, aerospace silicones in optically clear formats help keep optical performance consistent while supporting mechanical compliance across service temperature changes.
Our thermal interface materials for electronics cooling
We provide thermally conductive materials designed to offer reliable cooling solutions for electronics, modules and assemblies.
Product references for thermal management
- Dowsil™ 1-4173 thermally conductive adhesive: 1.8 w/m·k, flowable, with high tensile strength and no added solvent.
- Dowsil™ TC-2035 adhesive: 3.3 W/M·K: heat-cure, with stable performance at high temperatures up to 200°c.
- Dowsil™ TC-4515 thermal gap filler: 1.8 w/m·k: holding vertical position before and after cure, soft and compressible once cured.
- Dowsil™ TC-4535 CV thermally conductive gap filler: 3.5 W/M·K, with controlled volatility.
Where heat is the constraint, these are the kinds of aerospace silicones engineers evaluate to close gaps, improve thermal contact and maintain compliance.
Our electrically conductive materials for EMI shielding
We provide electrically conductive materials to ensure high shielding effectiveness from electromagnetic interference across a wide range of frequencies.
Product reference for emi shielding
- Dowsil™ EC-6601 electrically conductive adhesive: sealant for EMI shielding across a wide range of frequencies, usable as an adhesive or formed-in-place gasket, adhering to a variety of substrates, with high elongation for flexible joints.
This is a clear example of aerospace silicones being selected not just for joining, but for functional system performance.
Spacecraft and satellites: controlled volatility and low outgassing
Spacecraft and satellites operate in high vacuum where outgassing can disrupt electronic systems, optical devices and thermal radiators, and volatiles can condense on camera lenses. To address this, we offer space-grade silicones that meet NASA requirements for low thermal vacuum outgassing, with physical and electrical stability across a wide temperature range. We also provide controlled-volatility sealants with low collected volatile condensable materials (CVCMS) and high elongation for stress relief, with reference to ASTM E595.
Product references for space-grade sealing and encapsulation
- Dowsil™ 6-1104 controlled volatility sealant and Dowsil™ 6-1125 controlled volatility sealant: extrudable, non-slump materials meeting NASA low outgassing requirements, with easy repairability and stability across a range of frequencies, temperatures and humidity, supporting protection from temperature extremes, humidity, radiation, thermal shock, atomic oxygen and mechanical vibration.
- Dowsil™ 93-500 space grade encapsulant (thixotropic): exceeding NASA requirements for low outgassing.
For space builds, many teams start their aerospace silicones selection with outgassing performance and controlled volatility, then move to form factor (flowable vs thixotropic) and process fit.
Processing choices: cure systems and why they matter
Our product tables list cure systems including one-part condensation, two-part addition, two-part condensation and UV cure. Cure system selection affects dispensing method, handling time, whether heat or uv is part of the line, and how the material behaves during build. This is why aerospace silicones selection is often a joint decision between design engineering and manufacturing engineering.
Surface preparation: primers for adhesion support
When surface preparation is required, we recommend starting with one of three primers:
- Dowsil™ 1200 OS primer, enhancing bonding/adhesion of RTV- and heat-cure silicones to metals, ceramics, glass, wood, masonry and structural plastics.
- Dowsil™ 92-023 primer, formulated for use with addition-cure silicones to mitigate surface poisoning; recommended for fr4, most metals and ceramics.
- Dowsil™ 1204 primer, enhancing adhesion to most metals, ceramics and plastics, especially with RTV cure.
Primers are often what makes aerospace silicones perform consistently across mixed substrates and real production variation.
Materials as part of your reliability strategy
In aerospace, defence, avionics and space, materials are part of the system. Selecting aerospace silicones well means matching the function (seal, bond, protect, dissipate heat, shield emi, optically couple) to the right silicone format, then aligning cure system and surface preparation to your build process. Our product selection brings these options together across adhesives, sealants, foams, coatings, gels, encapsulants, optically clear materials, thermal interface products and electrically conductive solutions.
Dow provides advanced materials solutions across multiple industries, including energy, electronics, transport and textiles, alongside aerospace and defence.
If you want to go further, contact us to discuss your application requirements and shortlist suitable aerospace silicones from our DOWSIL™, SYLGARD™ and SILASTIC™ ranges.
