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How to Spec EV Busbar Insulation or a Dielectric Barrier: What to Send H-O for a Quote
Dielectric parts attract underspecified RFQs because the part looks simple: a film rectangle, a folded sleeve, a plate with holes. The electrical duty hiding behind that geometry is what the quote actually prices, and it lives in numbers many drawings omit: the working voltage, the pollution degree, the spacing the design must hold, and the temperature at the nearest joint.
This is the ten-item checklist the H-O applications team works from for busbar wraps, underlays, interleaves, and dielectric plates, drawn from the parent application page's own what-to-send list, plus what engineering does with each item and what comes back.
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The ten things to send, and what each decides
| Send this | What it decides |
|---|---|
| 1. The job: through-thickness, surface, or both | The fundamental split. Resisting breakdown across the barrier and holding creepage and clearance along it are sized independently, and most converted parts do both. |
| 2. Working voltage | The anchor of the whole electrical spec; with the over-voltage category it drives the IEC 60664 spacing tables and the withstand expectation at the part's gauge. |
| 3. Over-voltage category (if known) | The transient context that drives clearance. If unknown, say so; the review proceeds with the architecture-level assumption flagged. |
| 4. Pollution degree of the location | The contamination context that drives creepage. A sealed interior and a condensing terminal area may carry different degrees, and the difference changes the spacing. |
| 5. Operating temperature | The family filter: standard films and papers across normal ranges, PEEK film near hot power connections, mica where very high temperature meets the electrical role. |
| 6. Form: film wrap, conformable paper, or rigid plate | The geometry fork between polyimide film, aramid paper, and glass-epoxy laminate; it also sets the converting method (score-and-fold versus machining). |
| 7. Any mechanical load | Whether the part must carry force or hold position, which moves the answer from films and papers to a structural laminate plate. |
| 8. Flame classification (e.g. UL 94) | Whether the grade must carry a listing, verified per grade and gauge on the data sheet. |
| 9. Part geometry and cut-outs | The developed flat pattern for a wrap, the clearance holes of an interleaf, or the machining features of a plate; folds are part of the creepage design. |
| 10. Prototype and annual volume | Converting method and price structure; prototype quantities through production runs are equally accepted. |
What engineering does with the list
Items 1 through 4 frame the electrical problem: the job split, then the voltage, transient, and contamination context that set the spacing expectations under IEC 60664.
Items 5 through 7 pick the family: polyimide film for tight wraps and thin underlays, aramid paper for complex folds and module interleaves, PEEK film for the hot zones, glass-epoxy laminate where the part carries load, and mica barrier sheet where very high temperature joins the electrical role. Item 8 checks the flame listing per grade and gauge.
Item 9 becomes the converting plan: the developed flat pattern with score lines for a folded sleeve, kiss-cut adhesive presentation for peel-and-place, or the machining drawing for a plate. Item 10 sets method and pricing. The reply cites the grade's dielectric strength (IEC 60243 / ASTM D149) and CTI from the manufacturer's data sheet, and leaves the governing spacing where it belongs, with your design against the standard's tables.
What happens after you send it
- Drawing review. Typically opened the same business day; the reply is a family and pattern direction, or the specific missing items.
- Material direction and quote. Family and grade direction with the TDS attached, the developed flat pattern or machining approach, and pricing at your quantities.
- Samples. Typically 3 to 5 business days for common die-cut configurations on materials on hand; folded patterns sample flat with score lines so fit can be proven on the real bar.
- 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 sheet, 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 film, paper, laminate, or mica, we state no dielectric, CTI, creepage, or clearance number, and vehicle-level outcomes (FMVSS 305 context) belong to the vehicle program.
The mistakes this checklist prevents
| Spec mistake | What it causes | Checklist item that catches it |
|---|---|---|
| Geometry-only RFQ | A quote for a rectangle, not an insulation part; electrical review impossible | Items 1 and 2 |
| Pollution degree assumed pack-wide | Spacing margins that differ between sealed and condensing zones go unnoticed | Item 4 |
| Film specified where load exists | A wrap asked to be a standoff; position drifts in service | Item 7 |
| Fold pattern left to the shop floor | Creepage distance the folds provided disappears in a revision | Item 9, with folds on the controlled drawing |
| Flame class assumed family-wide | UL 94 listings are grade- and gauge-specific | Item 8 plus the TDS check |
| Material swap without a spacing re-read | Lower-CTI grade, same drawing, quietly smaller margins | The CTI note in the material direction |
Frequently asked questions
Can H-O calculate my required creepage and clearance?
No; those values come from the IEC 60664 tables applied to your working voltage, over-voltage category, pollution degree, and material group, and they belong to your design authority. What we do is converse with that calculation: pick the family whose CTI supports your material group, develop the fold pattern that delivers your surface distance, and confirm the grade data on the manufacturer's sheet. Send the required distances and the geometry; the part follows.
What does a busbar-wrap drawing need that a flat-part drawing does not?
The developed flat pattern with its score lines, or enough bar geometry for engineering to develop it: the wrap is a three-dimensional sleeve cut flat, and the folds are functional, since they extend the creepage path. The drawing should also call the adhesive zones and liner presentation if the line wants peel-and-place. If you only have the bar model, send that; pattern development is part of the review.
How do laminated constructions get specified?
By naming both jobs. Where one material cannot carry the structural and the thin high-dielectric surface role at once, a glass-epoxy plate is faced with a film or paper, and the drawing calls the construction as one part with each layer's job stated. Engineering proposes the lamination when the checklist items point that way; you do not need to arrive with the stack already designed.
What sample format proves a folded sleeve before tooling?
A flat, scored sample. Samples typically ship in 3 to 5 business days for common configurations, and a folded-part sample arrives flat with its score lines so your team folds it onto the real bar, checks the joint clearances and terminal cut-outs, and validates the creepage-relevant folds before the production die is committed.
Send the checklist, get a dielectric-part quote
Attach the geometry 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.
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Related reading
Request a quote for your EV busbar electrical insulation 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
- IEC 60664 (insulation coordination: the source of required creepage and clearance for your design).
- IEC 60243 and ASTM D149 (dielectric strength of solid insulating materials, thickness- and method-dependent).
- UL 94 (flammability classifications); FMVSS 305 (vehicle-level electrical safety context).
- Manufacturer technical data sheets: polyimide film, aramid paper, PEEK film, glass-epoxy laminate, mica barrier sheet.
This checklist supports a quotation workflow; it does not constitute design guidance for any specific pack, and required spacings come from IEC 60664 applied to your design. Grade-level values are confirmed on the manufacturer's current technical data sheet. 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, and does not certify the finished pack or vehicle.