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How to Spec Avionics Thermal Parts: What to Send H-O for a Quote
Avionics thermal parts attract underspecified quote requests because the geometry looks like the whole story: a pad with holes, a film on a liner, a graphite ply. What the quote actually prices is the duty behind it, whether the joint must isolate, how it moves, how hot it runs, and what contamination limits the bay carries. This is the ten-item checklist the H-O applications team works from, what engineering does with each item, and what comes back.
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The ten things to send, and what each decides
Avionics thermal parts attract underspecified RFQs because the geometry looks like the whole story: a pad with holes, a strip of film on a liner, a graphite ply. What the quote actually prices is the duty behind the geometry: whether the joint must isolate, how the joint moves, how hot it runs, and what contamination limits the bay carries.
This is the ten-item checklist the H-O applications team works from for dielectric pads, gap fillers, graphite TIM and spreaders, film layers, and gaskets, drawn from the parent application page's own engineering-review list, plus what engineering does with each item and what comes back.
| Send this | What it decides |
|---|---|
| 1. Electrical role of the joint | The gating question. Isolated joints restrict the choice to insulating families with ASTM D149 data; grounded joints admit conductive graphite, which usually wins the thermal comparison there. |
| 2. Joint mechanics: stiff, compliant, or cycling | Pump-out risk. A cycling or cover-compliant joint needs a reinforced pad or graphite that does not flow; a bolted-stiff joint can use the soft filler that gives the lowest impedance. |
| 3. Heat density and wattage class | The conductivity class the joint needs, compared per ASTM D5470 at pressure, not by the headline W/m·K. |
| 4. Worst-case gap, flatness, and clamp pressure | Reinforced pad versus gap filler, and the working point. A pad outside its pressure window underdelivers; a filler fills where a pad starves. |
| 5. Conduction path and converted format | Through-path TIM or lateral spreader. A spreader needs a destination (rail, wall, chassis mass); a spreader with nowhere to send heat just relocates it. |
| 6. Vibration and shock environment | Robust constructions at mechanical hot spots: polymer-enhanced graphite over pure graphite at handled interfaces, PEEK wear plies under retention hardware, laminated stacks where a loose film would powder. |
| 7. Contamination limits and outgassing | Per-grade ASTM E595 screening of the exact converted construction (base plus adhesive plus liner) against the program's limits, especially near optics and sensors. |
| 8. Environmental framing: DO-160 / MIL-STD-810 | The framing belongs in the material review, not just the box test plan, so the construction is chosen for the qualified environment. |
| 9. Geometry and liner presentation: DXF, STEP, or PDF | Footprint, fastener clearances, kiss-cut-on-liner format, lamination order (graphite plus dielectric boundary), the items that decide placement repeatability. |
| 10. Prototype and production volumes | Converting method and price structure. Every part is made to order; prototype quantities through full production runs are equally accepted, and MOQ varies by material and part. |
What engineering does with the list
Items 1 and 2 pick the path family: an insulating PROTECT or Sil-Pad TSP pad or a soft Gap Pad filler on isolated joints, or conductive eGRAF HiTherm or SpreaderShield graphite where item 1 says grounded, with item 2 steering away from soft fillers on cycling joints. Items 3 through 5 set the conductivity class, the working point, and the through-or-sideways direction.
Item 6 adds robust constructions (APTIV PEEK wear plies, polymer-enhanced graphite) at mechanical hot spots, and item 7 screens the construction per ASTM E595. A conductive ply is laminated with a Kapton dielectric boundary so the isolation travels with the part. Items 8 through 10 become the converting plan and the price structure.
What happens after you send it
- Drawing review. Engineering reviews the stack against the vendor TDS: electrical role, joint mechanics, heat density, pressure window, conduction path, vibration, and contamination limits.
- Material direction and quote. A family and grade direction with the TDS attached, the converted format (die-cut, kiss-cut on liner, graphite-plus-dielectric lamination), and pricing at your quantities.
- Samples. Typically 3 to 5 business days for common die-cut configurations on materials we keep on hand.
- Production. Standard runs ship about two weeks after drawing approval, including kiss-cut-on-liner and laminated configurations; expedited service is available. Ongoing parts run with material traceability and lot-code TDS records.
Documentation available on request: material technical data sheet, certificate of conformance, and lot traceability, under our ISO 9001:2015 certified quality management system. H-O is a die-cut converter, not a raw-material producer: we do not manufacture the raw pads, films, or graphite, we do not independently certify them, and box qualification to DO-160 or MIL-STD-810 belongs to the box builder.
The mistakes this checklist prevents
| Spec mistake | What it causes | Checklist item that catches it |
|---|---|---|
| Conductive graphite on an isolated joint | An electrical fault with excellent conductivity | Item 1, electrical role verified |
| Soft filler on a breathing joint | Pump-out; hot spot at hour three thousand | Item 2, joint mechanics named |
| Conductivity-first comparison | The W/m·K column inverts at your pressure | Items 3 and 4, ASTM D5470 at pressure |
| Spreader with no destination | The hot spot relocates into a closed box | Item 5, conduction path named |
| Unreinforced film under a retention clamp | The film powders under vibration | Item 6, robust construction |
| Family-level outgassing assumption | A lens fogs in a sensor bay | Item 7, per-grade ASTM E595 |
Frequently asked questions
What information do I need to send H-O to quote an avionics thermal part?
Ten items turn the geometry into a quotable drawing: the electrical role of the joint, the joint mechanics (stiff, compliant, or cycling), the heat density, the worst-case gap and clamp pressure, the conduction path (through or sideways), the vibration and shock environment, the contamination limits and outgassing, the DO-160 or MIL-STD-810 framing, the geometry and liner presentation as DXF, STEP, or PDF, and the volumes. Send what you have; engineering frames the rest and flags any assumption.
Can H-O cross-reference the TIM grade on my print?
In most cases, yes. If your drawing calls out a dielectric pad, gap filler, graphite film, or gasket by a brand part number, engineering identifies a comparable grade from the lines we convert, matching on impedance class per ASTM D5470 at your pressure, dielectric strength per ASTM D149, outgassing per ASTM E595, and the joint mechanics. It is an industry cross-reference, not a guaranteed drop-in, verified against the vendor TDS before quoting.
Can H-O laminate graphite with a dielectric boundary?
Yes, and it is the recommended way to use graphite near conductors. A conductive graphite ply is laminated to a Kapton or polyimide dielectric film so the isolation boundary travels with the part and cannot be left off at assembly. H-O die-cuts the laminated stack as one peel-and-place part. The isolation scheme, creepage, and clearance still belong to the program and are verified at every revision, but laminating the boundary onto the ply removes one way the verification can be defeated in the field.
Why does the joint's mechanical behavior belong on the drawing?
Because it changes the recommendation more than the wattage does. A joint described as cycling or cover-compliant needs a construction that resists pump-out, a reinforced pad or graphite that does not flow, while a bolted-stiff joint can use the soft filler that gives the lowest impedance. One word, bolted-stiff, cover-compliant, or cycling, lets engineering choose a construction that survives the joint's mechanics instead of one that only looks best on day one.
What lead time should I expect for samples and production?
Every avionics thermal part is made to order, including samples. Samples typically ship in 3 to 5 business days for common die-cut configurations on materials we keep on hand; standard production runs ship about two weeks after drawing approval, including kiss-cut-on-liner and laminated configurations; expedited service is available when timing is critical. MOQ varies by material and part, and prototype quantities through full production runs are equally accepted.
Send the checklist, get an avionics thermal quote
Attach the geometry and as many of the ten items as you have. If something is unknown, say so; the review proceeds with the assumption flagged.
Samples typically ship in 3 to 5 business days for common die-cut configurations on materials we keep on hand; standard production runs about two weeks after drawing approval; expedited service is available. MOQ varies by material and part.
Family-owned in Winsted, Connecticut since 1971 · ISO 9001:2015 certified · OEMs worldwide send us a drawing — and get back their part.
Related reading
Request a quote for your avionics thermal management part
Send H-O your drawing or describe the part—engineering reviews every RFQ and converts samples on your geometry.
Last updated · Reviewed by H-O Products engineering (ISO 9001:2015 certified converter, Winsted, CT).
References
- ASTM D5470 (thermal impedance at pressure, the path comparison basis); ASTM D149 (dielectric breakdown for isolated joints).
- ASTM E595 (outgassing, total mass loss and collected volatile condensable material, reported per grade).
- ASTM D1056 (compression behavior of the silicone gasket set); RTCA DO-160 and MIL-STD-810 (environmental framing, owned by the box builder).
- Manufacturer technical data sheets for the dielectric pad, gap filler, graphite TIM and spreader, polyimide and PEEK film, and silicone grades named on the parent application page.
This article summarizes thermal interface material-selection principles for avionics using the families and published test methods cited on the parent application page. Comparisons are qualitative; per-grade values quoted are maker-TDS figures and must be confirmed on the manufacturer's current technical data sheet at your pressure, thickness, and installed condition. Standards (ASTM, MIL-STD, RTCA DO-160) are cited by designation for context, not as a claim of qualification.
H-O is a precision die-cut converter, not a raw-material producer, and does not perform thermal design, certify materials, or qualify enclosures to DO-160 or MIL-STD-810; those belong to the box builder and its test houses.