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How to Spec a TIM, EMI Gasket, or Housing Seal: What to Send H-O for a Quote
Power-electronics interface parts come in threes: the TIM under the module, the conductive gasket on the seam, and the environmental seal on the cover, and the most efficient RFQ quotes them as the system they are. The checklist below is the one the H-O applications team works from, taken from the parent application page's own what-to-send list. Its first item is also its most important: name the goal.
A part that must move heat, a part that must close an electrical slot, and a part that must keep water out are three different parts, and the handful that must do two jobs at once need to be told so.
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The ten things to send, and what each decides
| Send this | What it decides |
|---|---|
| 1. The goal: thermal, EMI, or sealing | The family router, and the flag for combined-duty parts (a seal-and-shield gasket is called out explicitly, never assumed). |
| 2. Heat to dissipate / allowable temperature rise | The thermal budget that, with item 3, lets the grade be matched to its ASTM D5470 impedance curve rather than to a headline conductivity. |
| 3. Gap, flatness, and clamp pressure | The geometry that forks thin TIM versus gap filler, and the pressure that decides whether the chosen TIM will ever seat. |
| 4. Dielectric / working voltage need | The isolation gate: a live-to-grounded heat path rules graphite out and routes to boron nitride silicone. |
| 5. EMI frequency band and emissions limit | The shielding context (evaluated at assembly level per CISPR 25 / IEC 61000) that shapes the conductive-gasket family and cross-section. |
| 6. Target IP rating (if sealing) | The enclosure class per IEC 60529 the seal must support; the rating belongs to the tested housing. |
| 7. Operating temperature and any flame class | The endurance and listing filters; UL 94 classes are grade- and gauge-specific on the TDS. |
| 8. Part geometry or drawing | Footprints, seam paths, cut-outs, and cross-sections; for gaskets, the deflection window belongs here. |
| 9. Adhesive / liner requirements | How the parts present to the line: PSA zones, kiss-cut liners, pull-tabs, kitting across the three part types. |
| 10. Prototype and annual volume | Converting method and price structure; prototype quantities through production runs are equally accepted. |
What engineering does with the list
Item 1 routes each part: thermal requests toward graphite TIMs, boron nitride silicone pads, soft conformable gap pads, and the TIM pad-and-film library; EMI requests toward conductive silicone and conductive sponge gaskets; sealing requests toward silicone sponge and the related closed-cell families, with flame-retardant silicone sponge where a listing rides along.
Items 2 and 3 size the thermal joint on the D5470 curve at your pressure; item 4 runs the isolation gate; items 5 and 6 shape the gasket cross-section and the sealing plan, with the assembly-level standards left at assembly level; item 7 checks endurance and listings; items 8 through 10 set the dies, the presentation, and the price.
Where one gasket must shield and seal, the combined part is quoted as one engineered item and confirmed at the as-assembled compression.
What happens after you send it
- Drawing review. Typically opened the same business day; the reply is a family direction per part, or the specific missing items.
- Material direction and quote. Families and grade directions with data sheets attached, cross-sections and deflection windows for the gaskets, and pricing at your quantities.
- Samples. Typically 3 to 5 business days for common die-cut configurations on materials on hand, so the TIM can be bench-verified at your pressure and the gaskets compression-checked on the housing.
- Production. Standard production runs about two weeks after drawing approval; special orders are quoted to the job. MOQ varies by material and part.
Documentation available on request: material technical data sheets, certificate of conformance, lot traceability, and first-article inspection, under our ISO 9001:2015 certified quality management system. H-O is a die-cut converter, not a raw-material producer: we do not make the TIM, gasket, or sealing stock, we claim no impedance, shielding, or ingress value, and the CISPR 25 / IEC 61000 / IEC 60529 outcomes belong to your tested assembly.
The mistakes this checklist prevents
| Spec mistake | What it causes | Checklist item that catches it |
|---|---|---|
| Conductivity-only TIM callout | A grade that cannot be verified at the real joint; contact resistance surprises | Items 2 and 3, per ASTM D5470 |
| Graphite on an isolating path | An electrically conductive interface where isolation was required | Item 4 |
| Gasket without a deflection window | Under-compressed seam; emissions failure at assembly test | Item 8 |
| Combined duty discovered late | A shield that leaks water, or a seal that breaks seam continuity | Item 1, with both criteria named |
| Flame class assumed family-wide | UL 94 listings are grade- and gauge-specific | Item 7 plus the TDS check |
| Three parts, three uncoordinated POs | Mismatched liners and kitting; line-side confusion | Items 9 and 10, quoted as a set |
Frequently asked questions
Can I send the whole housing as one RFQ: TIM, gasket, and seals?
Yes, and it is the better request. The three parts are one interface system, they are commonly die-cut from coordinated dies, presented on liners that suit the same line, and kitted together. Quoting them as a set also forces the combined-duty questions (does the EMI gasket also seal? does the seal need a listing?) to be answered once, at the start, instead of per purchase order.
What if the clamp pressure is not final yet?
Send the range under consideration. The TIM direction can be set against the data-sheet impedance curves across that range, and the review will flag if the candidate family only works at the top of it, which is itself useful design feedback. The callout finalizes when the pressure does; the quote does not have to wait.
How is the EMI gasket's deflection window established?
From the seam geometry and the gasket cross-section: the window is the compression range within which the gasket maintains electrical continuity (and, for a combined part, the seal). Engineering proposes the cross-section and window from your seam drawing and closure plan, and the window then belongs on the controlled drawing, because under-compression after a service event is the classic field failure.
Do you certify the parts to CISPR 25 or IEC 60529?
No. Those standards apply to an assembly or a measurement, not to a raw material: CISPR 25 and the IEC 61000 series evaluate the assembly's emissions and immunity, and IEC 60529 rates the tested enclosure. The parts support those outcomes, the materials are evaluated against the cited methods through the manufacturer's data sheets, and H-O does not independently certify a material to them unless explicitly stated on the quote.
Send the checklist, get the interface set quoted
Attach the housing drawing and as many of the ten items as you have. Drawing review typically starts the same business day.
Samples typically 3 to 5 business days; production about two weeks; MOQ varies by material and part. Expedited service available.
Family-owned in Winsted, Connecticut since 1971 · ISO 9001:2015 certified · OEMs worldwide send us a drawing — and get back their part.
Related reading
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IndustryEV & Battery hubRead →
Request a quote for your EV power-electronics, BMS & inverter 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 stated pressure and thickness: the basis of a verifiable TIM callout).
- CISPR 25 and the IEC 61000 series (assembly-level emissions and immunity); IEC 60529 (enclosure ingress rating); UL 94 (flammability listings).
- Manufacturer technical data sheets: graphite TIMs, boron nitride silicone pads, soft conformable gap pads, TIM pads and films, conductive silicone and sponge EMI gaskets, silicone sponge and flame-retardant sponge seals.
This checklist supports a quotation workflow; it does not constitute design guidance for any specific assembly. Grade-level values are confirmed per the cited methods on the manufacturer's current technical data sheet at your conditions; assembly-level outcomes belong to your tested assembly. All parts are custom manufactured to order; minimum production run quantities vary by material and part. H-O is a die-cut converter, not a raw-material producer.