Avionics Thermal Management: Die-Cut Graphite Heat Spreaders, TIM Pads & Dielectric Interface Layers
Avionics thermal management is a conduction problem first: in a sealed LRU every watt must reach the chassis wall through solid interfaces, because there is no airflow inside to help. The die-cut layers below — graphite spreaders, TIM pads, and dielectric boundaries — are the parts of that path H-O converts to drawing.
H-O Products die-cuts and converts NeoGraf® SpreaderShield® and eGRAF® HiTherm® graphite, Rogers PROTECT™ and SECURE™ TIM pads, Sil-Pad® and Gap Pad® boron-nitride silicone pads, Kapton® and Apical® polyimide films, APTIV® PEEK film, AeroZero® thin polymer film, and BISCO® solid silicones into heat spreaders, thermal interface pads, dielectric isolation layers, and thermal-break gaskets for conduction-cooled avionics, radar, and cockpit systems, built to your drawing.
H-O is a materials converter: environmental qualification and airworthiness remain with the avionics integrator.
Built for: Conduction-cooled LRU and chassis thermal interfaces, power-supply and converter TIM pads, board-level graphite heat spreading, cockpit display and window-heater interface gaskets, radar and high-density electronics thermal paths, and dielectric isolation layers in conductive stacks.
Quick Answer
To specify an avionics thermal interface, answer the electrical question first. If the stack must electrically isolate, use a dielectric TIM: Rogers PROTECT series or Sil-Pad / Gap Pad boron-nitride silicone, with breakdown data per ASTM D149 on the TDS.
If the isolation scheme is confirmed elsewhere, graphite delivers more heat flow per mil: SpreaderShield flexible graphite for lateral heat spreading and eGRAF HiTherm for chassis-interface TIM duty, with thermal impedance framed per ASTM D5470 and outgassing per ASTM E595 on the maker’s data. The remaining zones and duties are mapped in the When-to-spec list on this page.
Values are per the TDS on file; see the material reference below for ordering details.
RTCA DO-160 (environmental conditions and test procedures for airborne equipment, cited qualitatively) · MIL-STD-810 (environmental engineering test methods, cited qualitatively) · ASTM D5470 (thermal impedance of thermally conductive insulation materials) · ASTM E595 (outgassing screening; %TML / %CVCM metrics per maker data) · ASTM D149 (dielectric breakdown of insulating TIM, per TDS) · UL 94 (flammability listings per TDS) · vendor TDS for per-grade values.
- Board-level hot-spot spreading: SpreaderShield graphite
- Chassis / frame conduction interface: eGRAF HiTherm graphite TIM
- Isolating TIM, fiberglass-reinforced: PROTECT / SECURE TIM pads
- Isolating gap filler, tolerance stacks: Sil-Pad / Gap Pad BN silicone
- Thin dielectric boundary ply: Kapton / Apical film
- Cockpit display / window-heater gasket: BISCO HT-12xx solid silicone
- High-wear clamp & retention points: APTIV PEEK film
- Thin thermal break / standoff: AeroZero thin polymer film
- Compliant mounting interfaces: BISCO silicone foam
- Optical / space-adjacent bays: HiTherm HT-1205 / HT-C3200 pure graphite and Sil-Pad TSP K1300, the grades with published outgassing data (ASTM E595)
Where are you in the spec process?
This page serves avionics and defense-electronics engineers who already hold a TIM call-out and engineers still mapping heat density, isolation, and qualification constraints. Pick the path that matches where you are. You don’t have to read the rest.
Send a drawing, get a quote
SpreaderShield or HiTherm graphite, PROTECT / SECURE TIM, Sil-Pad / Gap Pad BN silicone, Kapton or Apical film, APTIV PEEK, AeroZero film, or BISCO solid silicone on your drawing.
Skip to the quote form →Walk through the selection factors
Six selection factors (electrical isolation, heat density, conduction path, interface flatness, vibration, outgassing), a TIM selector by power class, and ten material families with TDS-cited test methods.
Start with selection factors →
How it works
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1
Send drawing
Upload a DXF, STEP, or PDF, or describe the assembly. A sample part works too. -
2
Material review
Engineering reviews the interface against the vendor TDS: dissipated power and heat density, electrical isolation requirement, surface flatness and tolerance stack, clamping pressure, and the environmental qualification framing the box must meet. -
3
Prototype
Typical prototype lead time is 5–10 business days after drawing review, depending on material availability, tooling, and inspection requirements. Made-to-order; MOQ varies by material and part. -
4
Production
Standard production runs ship about 2 weeks after drawing approval, including kiss-cut-on-liner and laminated configurations. Expedited service available. Ongoing parts run with material traceability and lot-code TDS records.
What are you cooling or isolating?
Application Zones
Five distinct material problems hide inside a conduction-cooled avionics build: the LRU and chassis interfaces, where the thermal path crosses mechanical joints. The power-conversion hardware, where heat density is highest and isolation is usually mandatory. The cockpit displays and heated windows, where thermal management meets optics and crew. The radar and high-shock electronics, where vibration punishes every interface. And the dielectric isolation layer itself, the films and pads that make conductive thermal materials safe to use at all.
Click a tab to see the interface, the constraint, and the material families H-O converts for that zone.
Conduction-cooled LRU & chassis interfaces
Most avionics cool by conduction: heat leaves a card through its thermal frame, crosses the card-rail joint, walks the chassis wall, and exits at a coldplate or fin field. Every mechanical joint in that chain is a thermal resistance, and the converted parts exist to shrink them.
Where the chassis grounding and isolation scheme permits a conductive path, eGRAF HiTherm graphite TIM sheets (HT-1205 / HT-1210 / HT-1220 pure graphite, −40 to +400 °C; HT-2505 / HT-2510 polymer-enhanced, −25 to +125 °C per the NeoGraf TDS) carry the frame-to-wall and box-to-coldplate interfaces, conforming to machined surfaces at low clamp pressure, with thermal impedance framed per ASTM D5470 and low-outgassing data per ASTM E595 reported on the maker’s documentation for many grades.
Graphite is electrically conductive: it must be verified against the module isolation scheme, chassis grounding, creepage and clearance, and overall system isolation before specification. Where that verification fails, the interface moves to the dielectric pad families in the next zones. [3] [7]
Grade-level properties, standards and caveats for these families are in the material reference below — one card per family, with the TDS links.
Power supplies, converters & module baseplates
Power conversion is where avionics heat density peaks and where electrical isolation is most often mandatory: the baseplate joint must move tens of watts while holding off the working voltage. The dielectric TIM families own this zone. Rogers PROTECT series pads (fiberglass-reinforced silicone constructions such as 1500FG) and the SECURE series carry documented thermal impedance per ASTM D5470 and breakdown voltage per ASTM D149 on their TDS, built for bolted module interfaces.
Sil-Pad TSP reinforced pads cover the classic discrete and brick mounting duty, and Gap Pad TGP soft gap fillers take the tolerance-stack joints where surfaces cannot be machined flat. The selection discipline is pressure: every one of these materials performs to its TDS only inside its specified clamp-pressure window, so the fastener pattern and torque belong on the drawing next to the material call-out.
Grade-level properties, standards and caveats for these families are in the material reference below — one card per family, with the TDS links.
Cockpit displays, bezels & window-heater interfaces
Cockpit electronics add optics and crew to the thermal problem. Display stacks dissipate real power behind glass that must stay clear and uniform. Heated windshields and side windows terminate their heater films at busbars and connectors that need defined thermal and electrical interfaces. And every bezel is simultaneously a gasket, a thermal break, and a tolerance absorber.
The working family is BISCO HT-12xx solid silicone (HT-1240 through HT-1270): dense, temperature-stable sheet that die-cuts into bezel gaskets, thermal isolation frames, and heater-termination pads, with hardness and mechanical data per the Rogers TDS.
SpreaderShield graphite plies spread display-driver heat laterally behind the stack where the isolation scheme allows, bounded by Kapton film where it does not, and AeroZero thin polymer film provides low-conductance breaks where a display must be thermally decoupled from a hot frame. Environmental behavior for all of it is framed by the box-level DO-160 campaign the integrator owns. [12] [1]
Grade-level properties, standards and caveats for these families are in the material reference below — one card per family, with the TDS links.
Radar, RF & high-shock electronics
Radar and defense electronics push the same conduction-cooling problem into harsher mechanics: sustained vibration spectra, shock events, and thermal cycling that environmental campaigns frame per MIL-STD-810 and DO-160, cited here qualitatively because the campaign belongs to the box, not the material.
For converted parts, the harshness changes the priorities: TIM materials must hold position and properties through vibration, which favors reinforced constructions (PROTECT fiberglass-reinforced pads, Sil-Pad TSP) and the polymer-enhanced HiTherm HT-25xx grades (−25 to +125 °C; check the cold-soak category before specifying) over fragile films; clamped joints earn APTIV PEEK film wear plies where retention hardware would otherwise chew through softer layers.
And every material in an RF-adjacent bay gets screened for what it sheds, with outgassing per ASTM E595 the gate for optical and space-adjacent payloads. The drawing should carry the vibration and shock framing so material review can check the construction, not just the conductivity. [2] [11]
Grade-level properties, standards and caveats for these families are in the material reference below — one card per family, with the TDS links.
Dielectric isolation layers & thermal breaks
The isolation layer is what makes the rest of this page usable. Graphite spreaders and TIMs are electrically conductive. Avionics boards are full of exposed conductors. And the layer between them is a designed component, not an assumption. Kapton HN / FN and Apical polyimide films are the working dielectric boundary: thin, thermally stable, converting-friendly, with breakdown data per ASTM D149 on the TDS (where the isolation ply also sits in the heat path, Kapton MT is the thermally conductive polyimide grade that cuts the layer's thermal penalty), die-cut to bound every conductive ply with defined margins and laminated to the graphite so the boundary cannot be omitted at assembly.
APTIV PEEK film steps in where the isolation ply also takes mechanical abuse, and AeroZero covers the standoff-and-thermal-break jobs where conductance, not just voltage, must be limited. The honest engineering position: isolation requirements flow from the system, creepage, clearance, grounding scheme, altitude, and this page frames materials qualitatively against that system design, which remains the integrator’s. [5] [10]
Grade-level properties, standards and caveats for these families are in the material reference below — one card per family, with the TDS links.
Six decisions that drive your avionics TIM spec
Avionics thermal interfaces are system decisions wearing material names. The right TIM satisfies six constraints at once, and missing one produces a box that passes thermal test and fails in service: a spreader that shorts a creepage path, a pad outside its pressure window, a film that powders under vibration.
Answer the electrical question before the thermal one. The single most consequential property of a graphite TIM is not its conductivity. It is that it conducts electricity. Whether the thermal path may be conductive is a system-design fact to confirm, never a default to assume.
Show all 6 selection factors tap to expand
Graphite (SpreaderShield, HiTherm) delivers maximum heat flow where the isolation scheme permits a conductive path. Dielectric pads and films (PROTECT / SECURE, Sil-Pad / Gap Pad, Kapton, PEEK) carry the interfaces that must hold off voltage, with breakdown per ASTM D149 on the TDS. Mixed stacks bound graphite with film.
Read the six factors below in order. The isolation answer halves the candidate list, heat density picks the family within the half, the conduction path sets the format, flatness sets the thickness, vibration sets the construction, and outgassing gates anything near optics or space.
Electrical isolation: the gating question
Graphite heat spreaders and graphite TIMs are electrically conductive and must be verified against the module isolation scheme, chassis grounding, creepage and clearance, and overall system isolation requirements before specification. Isolated-baseplate hardware alone does not guarantee safe use in every chassis context. Where the verification holds, graphite’s heat flow per mil is the prize.
Where it fails or cannot be confirmed, the dielectric families, PROTECT / SECURE, Sil-Pad / Gap Pad, Kapton-bounded stacks, carry the interface with breakdown data per ASTM D149.
State the isolation requirement on the drawing; it is the first thing engineering review checks. [5]
Heat density and the wattage class
A position sensor dissipating two watts, a processing module at sixty, and a converter brick at two hundred are three different material problems. Low-density interfaces tolerate almost any compliant pad, and economics decide. Mid-class LRU interfaces benefit from graphite’s impedance per ASTM D5470 where permitted, or reinforced dielectric pads where not.
The highest densities demand the engineered TIM constructions, PROTECT / SECURE, Gap Pad TGP high-conductivity grades, at their specified clamp pressures. Put dissipated watts and contact area on the drawing, not just “needs TIM”; the class picks the family. [3]
Conduction path and converted format
Heat leaves a conduction-cooled box along a designed path: die to frame, frame to rail, rail to wall, wall to coldplate.
Each joint wants a different converted format: thin graphite sheet at machined frame interfaces, kiss-cut pads-on-liner for repetitive card builds, laminated film-bounded spreaders behind boards, soft gap fillers where tolerances stack at module lids. Map the path before specifying the parts, and let each joint’s geometry pick its format. H-O converts all of them, die-cut, kiss-cut, slit, laminated, to the mounting pattern on the drawing.
Interface flatness, pressure window, and thickness
Every TIM performs to its TDS only inside its clamp-pressure window, and the window is set by the joint: machined-flat frames need thin high-performance layers. Stamped covers and tolerance stacks need conformable gap fillers that fill without overloading fasteners. Thickness is not a free parameter, it trades directly against impedance and against the pressure the hardware can deliver. State surface condition, flatness, fastener pattern, and torque on the drawing so the pad’s working point is engineered rather than discovered. [8]
Vibration, shock, and construction robustness
Avionics environmental campaigns, framed per MIL-STD-810 and DO-160 and owned by the integrator, punish TIM constructions mechanically: unreinforced films crack and powder, soft pads pump out of joints that breathe, and brittle layers fail at retention hardware.
The countermeasures are constructions, not chemistries: fiberglass-reinforced pads (PROTECT, Sil-Pad TSP), polymer-enhanced graphite (HiTherm HT-25xx, −25 to +125 °C), laminated film-bounded stacks, and PEEK wear plies at clamp points. Send the vibration framing with the drawing; construction review is part of material review. [2]
Outgassing and contamination-sensitive bays
Optics, sensors, and space-adjacent payloads gate materials on what they shed: outgassing screened per ASTM E595, with %TML and %CVCM values reported per grade on maker documentation, NeoGraf publishes E595 data for the pure-graphite HiTherm HT-1200 series and HT-C3200 (HT-1205 TML 0.06% / CVCM <0.01%, HT-C3200 0.01% / <0.01%; the polymer-enhanced HT-2500 series outgasses and is excluded for optical and space systems, and SpreaderShield has no published values), Henkel publishes NASA outgassing data for Sil-Pad TSP K1300 (TML 0.36% / CVCM 0.09%), TSP 1600S, TSP 3500 and Gap Pad TGP 3000 but not for TSP 900 or TGP 1500, and silicone families reviewed for volatile content where lenses and windows live downstream. The discipline is per-grade: a family-level assumption is not a screening. Flag contamination-sensitive bays on the drawing and the material set narrows accordingly. [4]
Specification Tools
Two tools to take you from “I have an avionics thermal problem” to here’s what to put on the drawing: a TIM selector that maps your power class, isolation requirement, and joint condition to a material family, and a side-by-side comparison matrix of every family on this page.
1. Avionics TIM selector by power class
Pick the interface’s power class, the electrical requirement, and the joint condition. The selector maps them to a TIM family with the reasoning, and flags the isolation verification whenever a conductive material is in play. Qualitative, per the H-O application research and the material TDS.
Pick a power class, an electrical requirement, and a joint condition
The result returns a recommended TIM family, the reason it fits, and a one-click path to its entry in the material reference below.
2. Side-by-side: avionics thermal material matrix
Every material family called out on this page, with its construction, electrical class, and the interface it fits. Click a column header to sort. Click any material name to jump to its accordion entry and full TDS reference.
| Material | Construction | Flame / FST data (TDS) | Key test methods | Form factor | Best for | |
|---|---|---|---|---|---|---|
| Graphite heat spreading (electrically conductive) | ||||||
| SpreaderShield Flexible GraphiteSS350 / SS400 / SS500 / SS600; FLX laminates | Flexible graphite sheet | Per NeoGraf TDS | ASTM E595 (maker) | Lateral hot-spot spreading | ||
| eGRAF HiTherm Graphite TIMHT-1205 / HT-1210 / HT-1220; HT-2505 / HT-2510 | Graphite / polymer-enhanced | Per NeoGraf TDS | ASTM D5470, E595 | Chassis conduction TIM | ||
| Dielectric TIM pads | ||||||
| Rogers PROTECT / SECURE TIMPROTECT 1500FG + series; SECURE series | Reinforced silicone TIM | Per Rogers TDS | ASTM D5470, D149 | Bolted power interfaces | ||
| Sil-Pad TSP SeriesTSP 900 class and up (per TDS) | BN silicone, reinforced | Per Henkel TDS | ASTM D5470, D149 | Discrete / brick mounting | ||
| Gap Pad TGP SeriesSoft through high-conductivity grades | Soft BN silicone filler | Per Henkel TDS | ASTM D5470 | Tolerance-stack joints | ||
| Films, breaks & gaskets | ||||||
| Kapton / Apical Polyimide FilmHN general; FN bondable | Polyimide film | Per DuPont TDS | ASTM D149 | Dielectric boundary plies | ||
| APTIV PEEK Film1000 / 2000 series; XPI A105–B105 | PEEK film | Per Victrex TDS | Per Victrex TDS | Clamp / wear / rugged dielectric | ||
| AeroZero Thin Polymer FilmPolyimide-aerogel film | Aerogel film | Per maker TDS | Per maker TDS | Thermal breaks, standoffs | ||
| BISCO HT-12xx Solid SiliconeHT-1240 / HT-1250 / HT-1260 / HT-1270 | Solid silicone sheet | Per Rogers TDS | ASTM D2240 (per TDS) | Display / window-heat gaskets | ||
| BISCO Silicone FoamHT-800 series; BF grades | Closed-cell silicone foam | UL 94 / E162 / E662 (TDS) | ASTM D1056 | Compliant mounting pads | ||
Skip ahead and request your engineering review now
If your drawing already calls out a SpreaderShield, HiTherm, PROTECT, SECURE, Sil-Pad, Gap Pad, Kapton, APTIV, or BISCO grade, send it over for engineering review.
Avionics thermal failures you can prevent at spec
Avionics thermal failures rarely show at acceptance test. The box passes thermal survey, the interfaces read cool, qualification closes. Then field hours accumulate and a hot spot drifts: a pad pumped out of a breathing joint, a film powdered under vibration, a spreader found a creepage path nobody re-checked. Five patterns cover most of what fails in this zone, and each one is a specification decision made before the box ships.
The expensive TIM failure is electrical, not thermal. A degraded interface costs margin. A conductive spreader across an unverified isolation path costs the box. The verification belongs at spec, on the drawing, in writing.
Show all 5 failure modes tap to expand
1. A graphite ply lands on an unverified isolation path
A graphite spreader solves a display-driver hot spot beautifully in the lab, then a design revision moves a connector, and the conductive ply now sits a clearance violation away from exposed conductors.
Nothing fails until contamination, vibration, or tolerance stack closes the gap. The fix: treat every conductive thermal material as an electrical component: verify the isolation scheme, chassis grounding, creepage and clearance at every revision, bound graphite with laminated Kapton so the boundary travels with the ply, and record the verification on the drawing. [10]
2. A pad specified outside its pressure window
A high-performance TIM pad underdelivers in service because the joint never loaded it to its working range: too few fasteners, a compliant cover, or torque relaxed by thermal cycling. The TDS number was real. The joint was not. The fix: engineer the working point, fastener pattern, torque, stiffness, against the pad’s specified clamp-pressure window per the TDS, and where the structure cannot deliver pressure, change family: soft gap fillers fill at low stress where reinforced pads starve. [8]
3. Pump-out at a joint that breathes
A soft thermal interface in a joint that flexes with thermal cycling slowly migrates: each cycle works material outward until the center runs dry, and the interface that passed qualification fails at hour three thousand. The fix: match construction to joint mechanics. Joints that breathe favor reinforced pads (PROTECT, Sil-Pad TSP) or graphite sheet that does not flow. Soft fillers belong where gaps are static. State the joint’s mechanical behavior, bolted-stiff, cover-compliant, cycling, on the drawing. [9]
4. An unreinforced film at a vibration-punished clamp point
A thin film ply, dielectric or graphite, sits under a wedge-lock or retention clamp, and the vibration spectrum the box is qualified to grinds it: the film fragments, particles migrate, and the interface opens. The fix: put reinforced constructions at mechanical hot spots: polymer-enhanced HiTherm grades over pure graphite at handled interfaces, PEEK film wear plies under retention hardware, and laminated stacks where a loose film would powder.
The environmental framing (MIL-STD-810 / DO-160) belongs in the material review, not just the box test plan. [2]
5. A family-level outgassing assumption in a sensor bay
A thermal material cleared for the avionics bay migrates into an optical sensor assembly on the assumption that the family is “low outgassing.” Months later a lens fogs. Outgassing is a per-grade property: %TML and %CVCM per ASTM E595 are reported grade by grade on maker documentation, and adhesive layers, liners, and laminations each add their own contribution. The fix: screen the exact converted construction, base material plus adhesive plus liner residue, against the program’s contamination limits, per grade, per E595 data. [4]
Material reference
Detailed reference for the ten material families on this page: the graphite heat-spreading set (SpreaderShield flexible graphite, eGRAF HiTherm TIM), the dielectric TIM pads (Rogers PROTECT / SECURE, Sil-Pad TSP, Gap Pad TGP), the film layer (Kapton / Apical polyimide, APTIV PEEK, AeroZero), and the gasket set (BISCO HT-12xx solid silicone, BISCO silicone foam). Thermal impedance is framed per ASTM D5470, dielectric breakdown per ASTM D149, outgassing per ASTM E595, and compression behavior per ASTM D1056, as listed on each TDS.
H-O die-cuts and converts all of them to drawing. Per-grade values are per the TDS on file, not headline numbers.
SpreaderShield Flexible Graphite (SS350 / SS400 / SS500 / SS600, FLX Laminates)
Lateral hot-spot spreading · electrically conductive · per NeoGraf TDS
SpreaderShield buys spreading area without thickness. The conversion that makes it safe is the laminated dielectric boundary: specify the bounded construction, not a bare ply, anywhere exposed conductors exist. Per-grade values per the NeoGraf TDS on file.
eGRAF HiTherm Graphite TIM (HT-1205 / HT-1210 / HT-1220; HT-2505 / HT-2510)
Chassis conduction TIM · electrically conductive · ASTM D5470 framing per maker
HT-12xx is the thin, low-impedance pick for machined stiff joints; HT-25xx trades a little impedance for conformability and handling robustness at tolerance joints and high-touch builds, inside a narrower −25 to +125 °C window (HT-12xx: −40 to +400 °C), and its polymer content outgasses, so it stays out of optical and space-adjacent bays. Both are conductive: the isolation verification belongs on the drawing.
Rogers PROTECT / SECURE TIM Pads (incl. PROTECT 1500FG)
Bolted power interfaces · isolating, reinforced · ASTM D5470 / D149 per TDS
Specify PROTECT / SECURE where power and isolation collide, and engineer the fastener pattern to the pad’s pressure window per the TDS. The reinforcement is what makes these pads assembly-proof. Per-grade values are on the Rogers TDS on file.
Sil-Pad TSP Series (Reinforced BN Silicone)
Discrete & brick mounting · isolating insulator pads · per Henkel TDS
The working default where isolation is required and the joint is reasonably flat. Move up to PROTECT / SECURE as density climbs, or to Gap Pad where the gap is uneven. Per-grade values per the Henkel TDS on file.
Gap Pad TGP Series (Soft Conformable Gap Fillers)
Tolerance-stack joints · isolating, soft · per Henkel TDS
Gap fillers fill. They do not clamp. Specify thickness from the real measured gap range, not the nominal, and keep the soft grades where parts are fragile. Per-grade values per the Henkel TDS on file.
Kapton HN / FN & Apical Polyimide Film
Dielectric boundary plies · thin, thermally stable · ASTM D149 per TDS
The boundary should travel with the conductive ply: specify the laminated construction so assembly cannot omit it. Film grade and thickness follow the breakdown requirement per ASTM D149 on the TDS.
APTIV PEEK Film (1000 / 2000 Series; XPI A105–B105)
Clamp points & rugged dielectric duty · per Victrex TDS
PEEK is the film you specify where vibration and hardware would destroy anything softer. It is not a heat spreader. It is the layer that keeps the rest of the stack intact. Per-grade values per the Victrex TDS on file.
AeroZero Thin Polymer Film
Thermal breaks & standoffs · polyimide-aerogel film · per maker TDS
- AZ-TPS GR 100 · DualZero TPS GR 201 · QuadZero TPS GR 400 graphite-faced constructions — spread heat along the face while insulating through the thickness (UL 94 VTM-0 film; V-0 laminates)
- AZ-TPS 102 / 103 / 104 low-outgassing acrylic-adhesive configurations, ASTM E595 TML <1% / CVCM <0.1% — the acrylic system carries a lower temperature ceiling than silicone grades, verify on the TDS
- AZ-TPS 100 · AZ-TPS 101 single- and double-sided silicone-PSA aerogel film, 190–216 µm, UL 94 VTM-0
- AZ-TPS PI 100 polyimide-faced aerogel film, 240 µm, UL 94 VTM-0 — durable outer skin for handling and wear
AeroZero covers the jobs between film and blanket: thermal resistance in tenths of a millimeter. Treat it as a precision die-cut component. Geometry carries the value.
BISCO HT-12xx Solid Silicone (HT-1240 / HT-1250 / HT-1260 / HT-1270)
Display & window-heater gaskets · dense solid silicone · per Rogers TDS
Solid silicone where sponge would relax and foam would crush: defined compression at defined thickness. Pick durometer from the joint’s closure force per the TDS, and keep optical-adjacent grades clean-handled.
BISCO Silicone Foam (HT-800 Series, BF Grades)
Compliant mounting interfaces · closed-cell · ASTM D1056 per TDS
The compliant partner to the rigid thermal stack: takes tolerance, damps rattle, and seals covers without loading the thermal joints. Match firmness to closure force per ASTM D1056 on the TDS.
Glass-Epoxy Laminate (NP500A G-10 / NP510A FR-4 / NP511 G-11)NEMA LI 1 grades · busbar supports, plates, barriers · 1/32″–1/4″ per the dossier
Glass-epoxy grades map to the NEMA LI 1 G-10 / FR-4 / G-11 designations; thickness range and the UL 94 V-0 flag are per the project dossier, and per-grade dielectric and mechanical values are per the maker TDS. Browse the grade families: FR-4 (NP510A) and G-11 (NP511), or the full glass-epoxy family.
Deep-dive answers below — or skip straight to the quote
Everything below this line is the reference tail: the engineer-grade FAQ, the glossary and the governing standards. If you already have a drawing set or can describe the box, the watts, and the interface stack, the intake form takes about two minutes.
Avionics thermal management: engineer-grade FAQ
Fifteen of the questions we hear most from avionics, radar, and defense-electronics engineers and from aerospace purchasing teams. If your question isn’t here, send a drawing or call, engineering picks up.
What thermal interface materials are used in avionics?
Two classes, split by the electrical question. Where the isolation scheme permits a conductive path: graphite, SpreaderShield flexible graphite for lateral spreading and eGRAF HiTherm sheets for chassis conduction TIM, with impedance framed per ASTM D5470 on maker data. Where the interface must isolate: dielectric constructions, Rogers PROTECT / SECURE reinforced pads, Sil-Pad TSP insulators, Gap Pad TGP soft fillers, with breakdown per ASTM D149 on the TDS, plus Kapton film as the thin boundary ply in mixed stacks. [3]
Is graphite TIM safe to use in an avionics box?
Only after verification. Graphite is electrically conductive, so before any graphite spreader or TIM is specified it must be verified against the module isolation scheme, chassis grounding, creepage and clearance, and overall system isolation requirements. Isolated-baseplate hardware alone does not guarantee safe use in every chassis context. Where verification holds, graphite delivers the best heat flow per mil in this set. Where it does not, the dielectric pad families carry the joint. The verification belongs on the drawing. [7]
What is conduction cooling, and why does it dominate avionics?
Conduction-cooled avionics move heat through solid paths, die to frame to rail to chassis to coldplate, instead of blowing air across boards, because sealed boxes survive altitude, dust, and moisture that airflow designs cannot. The consequence for materials: every mechanical joint in the path is a thermal resistance, and the converted TIM layers at those joints, graphite sheets, dielectric pads, film-bounded spreaders, are where the thermal budget is won or lost.
How do I choose between a Sil-Pad, a Gap Pad, and a PROTECT pad?
By joint condition and power class, in that order. Flat, stiffly clamped joints at moderate power: Sil-Pad TSP reinforced insulators. Uneven gaps and tolerance stacks: Gap Pad TGP soft fillers, thickness from the measured gap range. High-power bolted interfaces: PROTECT / SECURE reinforced constructions at their specified clamp-pressure window. All three isolate, with data per ASTM D5470 / D149 on their TDS. The joint mechanics pick among them. [9]
What does ASTM D5470 actually measure?
Thermal impedance of a thermally conductive insulation material under controlled pressure: the temperature drop across the sample per unit heat flux, at stated thickness and clamp pressure. It is the right framing for TIM comparison because it captures the interface as used, material plus contact, not just bulk conductivity. The discipline it enforces: a TIM number means something only at its stated pressure, which is why the fastener pattern belongs on the drawing. [3]
When does outgassing (ASTM E595) matter for thermal materials?
Whenever optics, sensors, or space-adjacent payloads share the volume. ASTM E595 screens materials by total mass loss (%TML) and collected volatile condensable materials (%CVCM) under vacuum bake. Values are reported per grade on maker documentation, NeoGraf publishes E595 data for the pure-graphite HiTherm HT-1200 series and HT-C3200 (not the polymer-enhanced HT-2500 series, and SpreaderShield has no published values), and the screening must cover the whole converted construction including adhesives and liners. Program contamination limits decide pass / fail. The method itself is a screening, not a certification. [4]
What gaskets go around cockpit displays and heated windows?
Dense solid silicone: the BISCO HT-12xx series (HT-1240 through HT-1270), die-cut into bezel gaskets, thermal isolation frames, and heater-termination pads. Solid construction holds defined compression at defined thickness where sponge would relax, durometer is picked from the joint’s closure force per the Rogers TDS, and the material’s temperature stability suits the window-heat environment. Thermal breaks behind displays use AeroZero film where the stack must decouple from a hot frame. [12]
How do DO-160 and MIL-STD-810 relate to TIM selection?
They frame the environment the box, and therefore every interface inside it, must survive: temperature and altitude, vibration spectra, shock, humidity. The campaigns belong to the integrator and are cited here qualitatively, but they drive material construction choices directly: reinforced pads and polymer-enhanced graphite where vibration is punishing, PEEK wear plies at retention hardware, laminated boundaries that cannot migrate. Send the environmental framing with the drawing so construction review happens at spec, not at failure analysis. [1]
Can H-O laminate graphite with a dielectric boundary?
Yes, and for avionics work it is the recommended converted form: graphite ply plus Kapton FN (heat-sealable) or specified film boundary, laminated and die-cut as one part so the dielectric margin travels with the spreader and cannot be omitted at assembly. H-O laminates, die-cuts, and kiss-cuts these constructions to the mounting pattern, with material traceability and lot-code TDS records behind each layer.
Does H-O qualify boxes to DO-160 or certify TIM performance?
No. Box-level environmental qualification (DO-160, MIL-STD-810 campaigns) and airworthiness findings belong to the avionics integrator and its test houses. Thermal and dielectric values belong to the material makers’ TDS. H-O’s role is converting documented materials to your qualified drawing, repeatably, with the traceability records your qualification file expects, as an ISO 9001:2015 certified organization. [1]
Why does this page frame values as “per the TDS on file”?
Because TIM numbers are condition-dependent: impedance moves with pressure and thickness (ASTM D5470), breakdown with thickness and temperature (ASTM D149), outgassing with grade and construction (ASTM E595). A single headline number flatters one condition and misleads the rest. This page names the governing methods and keeps per-grade values on the manufacturer TDS, which H-O reviews against your drawing during quoting. [5]
How do orders run for made-to-order avionics TIM parts?
Send a drawing, BOM, or sample part. Engineering reviews the interface against the TDS layer, isolation requirement, power class, pressure window, environment, then quotes prototype and production. Everything is made-to-order against the drawing; MOQ varies by material and part. Typical prototype lead time is 5–10 business days after drawing review, depending on material availability, tooling, and inspection requirements. Lead-time details live in the process strip above and the quote form below.
What tolerances can H-O hold on a die-cut avionics TIM or spreader part?
Tolerance depends on the material class, the thickness, and the cut method. Soft foams and sponges move more than rigid laminates or films, so the achievable band is material-specific. Flag the critical dimensions on your drawing. Engineering confirms the achievable tolerance band for your geometry at drawing review, before tooling is committed. That review, not a generic chart, is what goes into the quote.
Can H-O work from a sample part instead of a drawing?
Yes. Send the sample part and engineering measures it, confirms the geometry back to you at drawing review, and quotes from that confirmed geometry. A drawing is still the fastest path, because nothing has to be reverse-measured. A DXF, STEP, or PDF with the material call-out shortens the review.
How does H-O document material traceability on shipped parts?
Every part ships against the source manufacturer's grade designation, and the TDS for that grade is the document of record for its properties. Lot-level material traceability is maintained under our ISO 9001:2015 certified quality management system, and certificates of conformance are available on request at quoting. If your program needs specific certs, flag them on the RFQ so they are priced in from the start.
Glossary: terms used on this page
Quick reference for the conduction-cooling, TIM, and isolation terminology used throughout. Each entry links to the relevant test method or section where applicable.
LRU (line-replaceable unit)
An avionics box designed for quick flight-line replacement: sealed, conduction-cooled, and mounted on rails or trays. Its thermal life depends on the converted interface layers at every conduction joint.
Conduction cooling
Removing heat through solid paths, frames, rails, chassis walls, coldplates, rather than airflow. The dominant avionics architecture because sealed boxes survive altitude and contamination. It makes every joint a thermal interface to engineer.
TIM (thermal interface material)
The converted layer that closes the microscopic air gaps between mating surfaces in a thermal path: graphite sheets, dielectric pads, gap fillers, films. Compared per ASTM D5470 [3] impedance at stated pressure.
Heat spreader
A high in-plane-conductivity layer (flexible graphite here) that moves heat laterally away from a hot spot to enlarge the effective conduction area. Electrically conductive. Bounded with film wherever circuits are nearby.
Thermal impedance vs conductivity
Conductivity is a bulk property. Impedance is the whole interface, material plus contact resistance, at stated thickness and pressure. TIM selection runs on impedance per ASTM D5470 [3]; bulk conductivity alone routinely misleads.
Dielectric (isolating) TIM
A TIM constructed to hold off voltage while moving heat: reinforced silicone pads, BN-filled constructions, film-bounded stacks. Breakdown behavior per ASTM D149 [5] on the TDS, at the specified thickness.
Clamp-pressure window
The pressure range over which a TIM performs to its TDS. Below it, contact starves. Above it, materials yield or fasteners overload. The joint design, fastener pattern, torque, stiffness, must deliver the window the TDS states.
Pump-out
The slow migration of a soft thermal interface out of a joint that flexes with thermal cycling. Countered by construction: reinforced pads, graphite sheet, or laminated stacks at joints that breathe. Soft fillers only where gaps are static.
ASTM E595 (%TML / %CVCM)
The vacuum-bake screening for outgassing: total mass loss and collected volatile condensable materials, reported per grade on maker data. The gate for optics- and space-adjacent bays. Program limits decide pass / fail. [4]
RTCA DO-160
Environmental Conditions and Test Procedures for Airborne Equipment: the civil-avionics qualification framework (temperature, altitude, vibration, and more), cited qualitatively on this page. The campaign belongs to the box integrator. [1]
Wedge-lock / card retainer
The clamping hardware that locks a conduction-cooled card into its rail and creates the card’s primary thermal joint. Its clamp force sets the local TIM pressure, and its mechanics are why wear-resistant plies (PEEK) exist at retention points.
Last updated · Reviewed by H-O Products engineering (ISO 9001:2015 certified converter, Winsted, CT).
Standards, test methods & technical references
The standards, test methods, and vendor technical data sheets cited throughout this page. Standards editions current as of June 2026. Verify against the publishing body before final spec. H-O converts materials that are tested to these methods on the source manufacturer’s TDS; H-O does not independently certify materials, and flight qualification remains with the airframer or system integrator.
Full standards & reference detail
RTCA DO-160
Environmental Conditions and Test Procedures for Airborne Equipment: the qualification framework for civil avionics environments, cited qualitatively by designation. Campaigns belong to the equipment integrator. rtca.org
MIL-STD-810
Department of Defense Test Method Standard: Environmental Engineering Considerations and Laboratory Tests. The military environmental framing cited qualitatively for high-shock and defense electronics. quicksearch.dla.mil
ASTM D5470
Standard Test Method for Thermal Transmission Properties of Thermally Conductive Electrical Insulation Materials: the impedance framing behind TIM comparison at stated pressure and thickness. astm.org/d5470
ASTM E595
Standard Test Method for Total Mass Loss and Collected Volatile Condensable Materials from Outgassing in a Vacuum Environment: the %TML / %CVCM screening cited for optics- and space-adjacent bays. Values per grade on maker data. astm.org/e0595
ASTM D149
Standard Test Method for Dielectric Breakdown Voltage and Dielectric Strength of Solid Electrical Insulating Materials at Commercial Power Frequencies: the breakdown framing on insulating TIM and film TDS. astm.org/d0149
UL 94
Standard for Tests for Flammability of Plastic Materials for Parts in Devices and Appliances: the flammability listings cited per grade and thickness on silicone-foam and pad TDS. shopulstandards.com (UL 94)
NeoGraf SpreaderShield / eGRAF HiTherm technical data
Manufacturer data for the flexible-graphite spreader and graphite TIM grades on this page: in-plane conductivity, impedance framing per ASTM D5470, and ASTM E595 outgassing data for the HiTherm HT-1200 series and HT-C3200. neograf.com
Rogers PROTECT / SECURE TIM technical data
Manufacturer TDS for the PROTECT (incl. 1500FG) and SECURE insulating TIM constructions: thermal impedance per ASTM D5470, breakdown per ASTM D149, and clamp-pressure windows per grade. rogerscorp.com
Henkel Bergquist Sil-Pad / Gap Pad technical data
Manufacturer TDS for the Sil-Pad TSP reinforced insulator pads and Gap Pad TGP gap fillers: conductivity ladder, breakdown data, and thickness ranges per grade. henkel-adhesives.com
DuPont Kapton / Kaneka Apical polyimide film technical data
Manufacturer data for Kapton HN / FN and Apical films: thickness ladder, dielectric breakdown per ASTM D149-class methods, and bondable FN constructions for laminated boundaries. dupont.com
Victrex APTIV PEEK film technical data
Manufacturer data for APTIV standard and XPI high-performance PEEK films: mechanical endurance, thermal capability, and dielectric properties per grade. victrex.com
Rogers BISCO solid silicone & silicone foam technical data
Manufacturer TDS for the HT-12xx solid silicone series and HT / BF silicone foams: hardness and mechanical data, compression-deflection per ASTM D1056, and flame data per grade. rogerscorp.com
Updated . Standards editions and links current at publication. Verify against the publishing body before final spec. H-O converts materials tested to the methods cited. Lot-specific documentation available on request.
Get an avionics thermal engineering quote
Send a drawing, BOM, or spec sheet. We typically respond within one business day with a material-family recommendation, prototype lead time, and TDS verification against your power class, isolation requirement, joint condition, and environmental framing.
Prefer to talk it through first? Contact the engineering team or call (860) 469-1144.
See also: related H-O application pages
Engineering content for the adjacent aerospace application categories, all under the aerospace, defense & space industry hub and the thermal management & insulation overview.
EMI shielding gaskets for aerospace & defense
The electromagnetic side of the same enclosures: conductive elastomer gaskets for avionics lids, doors, and panels. Read the page Application pageAvionics & electronics enclosure sealing
Environmental sealing, venting, and ingress protection for the boxes this page cools. Read the page Application pageElectrical insulation for aerospace power systems
The dielectric layer at machine scale: slot liners, phase barriers, and busbar insulation for aircraft electrical systems. Read the page Application pageAircraft vibration, NVH & shock isolation
Isolation mounts and damping materials for the racks and trays that carry these boxes. Read the page Application pageCryogenic & space systems insulation
The space-adjacent end of thermal management: low-outgassing materials and spacecraft insulation systems. Read the page Industry hubAerospace, defense & space materials
The full industry directory: every aerospace sub-application H-O converts for, from thermal insulation to EMI shielding. Open the hubMaterial data & standards. All material properties and ratings referenced on this page are taken from the source manufacturer’s technical data sheets and the cited standards: thermal impedance framed per ASTM D5470, dielectric breakdown per ASTM D149, outgassing screening per ASTM E595 (%TML / %CVCM per grade on maker data), compression behavior per ASTM D1056, flammability listings per UL 94 as listed per grade and thickness, and RTCA DO-160 / MIL-STD-810 cited qualitatively as environmental framing.
Electrically conductive thermal materials (graphite spreaders and TIMs) must be verified against the module isolation scheme, chassis grounding, creepage and clearance, and overall system isolation requirements before specification. This page frames performance qualitatively and keeps per-grade values on the TDS, where they belong. H-O converts materials tested to these methods; H-O does not independently certify materials, does not perform box-level qualification, and makes no airworthiness claims.
Verify against the vendor TDS and your program’s qualification basis for your specific application.
Conversion scope. H-O die-cuts and converts sheet, roll, and film stock to drawing in Winsted, Connecticut: die-cut and kiss-cut TIM pads, graphite spreaders with laminated dielectric boundaries, film plies, solid-silicone gaskets, and multi-layer laminated stacks, with material traceability and lot-code TDS records, as an ISO 9001:2015 certified organization. H-O does not manufacture raw material in-house.
Extruded or molded profiles are coordinated through a partner network. Lead-time and MOQ details are on the process strip and in the quote form above.