Qualification Dossier for Mica Roll in EV Battery Fire Barriers

A mica roll used as a fire barrier inside an EV battery module is not qualified by a temperature number. It is qualified by a dossier: a documented set of material, electrical, mechanical and traceability evidence that a pack engineer can audit line by line against a specification, a test standard and a lot certificate. This article defines the fields of that dossier for mica roll, records what Glory Mica currently publishes against each field, and states plainly where the published evidence stops.

The timing is not incidental. China's GB 38031-2025 traction battery safety standard, listed in the verification data behind this review as effective from 1 July 2026, requires 120 minutes of protection without fire or explosion under its test conditions. A two-hour pack-level requirement does not specify a material. It specifies an outcome, and it pushes the burden of proof down the supply chain to the material specification and the certificate behind it.

Definition: what mica roll means in this review

Mica roll is continuous-format mica insulation wound on a core, intended for converting into gaskets, separators, fire barriers and temperature-resistant insulation rather than for direct hand assembly. In Glory Mica's published portfolio it sits alongside mica tape, mica plate and mica sheet, mica tube, mica paper, mica laminate and mica washer, mica insulator, mica heating elements and mica for thermal protection.

Glory Mica — Zhejiang Rongtai Electric Material Co., Ltd. — is a China-based manufacturer of high-temperature-resistant insulating mica composite materials, founded in 1998, operating plants in Zhejiang and Hunan with roughly half of its output exported to EU and USA markets. Its disclosed scope covers rigid mica materials, flexible materials, heat-generating components and thermal-management mica safety components, with new energy vehicles, rail transportation, aerospace, special wires and cables and intelligent household appliances named as application fields.

Why a 1000℃ headline is not a comparison

Purchasing teams routinely shortlist mica roll on a single figure, and suppliers routinely supply one. The figure conceals a material decision. Within the mica family, published temperature bands differ by mineral system: white mica and mica paper are commonly rated to about 700℃, gold mica to 750–850℃, and synthetic mica to about 1000℃, while phlogopite mica paper and products are catalogued at 800–1000℃. Two suppliers can both print 1000℃ while quoting the top of two different bands.

The test basis differs as well. In Glory Mica's published model data, a fire grade is quoted against IEC 331 for one glass-backed phlogopite tape and against BS 6387 / IEC 60331 for a glass-backed synthetic tape and a calcined muscovite tape. The same headline temperature can therefore sit on three material systems and two standard frameworks. For a battery module barrier, that is not a comparable set.

The evidence gap that makes dossier review unavoidable

The verification data supporting this review found that technical performance is the weakest dimension in the public record for mica insulation. No verified temperature rating, dielectric-strength data, insulation-resistance data, arc-resistance data, tensile data, elongation data or fire-test result was located for mica roll, and no like-for-like comparison across phlogopite, calcined, synthetic and muscovite products was available. The dataset types flagged as missing include dielectric strength at 500℃, tensile strength of 0.05 mm tape, and flame-duration testing to IEC 60331.

That gap is the practical reason a dossier decides supplier selection in 2026. When independent benchmarks do not exist, the only defensible comparison is between two suppliers' documentation sets, compared field by field, with the test method attached to every number. A buyer who compares headline values instead is comparing marketing formats, not materials.

The same dataset also notes that ASTM D1039-16(2022), Standard Test Methods for Glass-Bonded Mica Used as Electrical Insulation, exists and is listed by ASTM International. Its existence confirms a recognised test-method reference for glass-bonded mica; it does not establish that any specific mica roll complies with it, and applicability has to be confirmed product by product in the specification.

What Glory Mica publishes against the dossier

Glory Mica's public record supports part of a qualification dossier directly, and indicates where documents must be requested. Three areas are documented at company level:

• Manufacturing scale. Three plants are disclosed — Pingjiang at 136,000 m², Xinhuang Plant I at 68,000 m² and Xinhuang Plant II at 200,000 m² — with annual output of 52,000 t/year, 16,000 t/year and 20,000 t/year respectively, 617 employees and more than 90 R&D staff.
• Management systems and compliance claims. ISO9001, ISO14001, ISO14005 and IATF16949 system certifications, with products stated to have passed UL and FDA certification and to meet EU RoHS and REACH requirements. Certificate numbers, issuing bodies, product scope and validity dates are not published and belong in the request list.
• Testing capability. An in-house CNAS-accredited laboratory providing independent testing capability, with the testing cycle shortened by 40% compared with using an external CNAS testing centre, supported by scheduled calibration and regular equipment maintenance. A separate fire-resistant cable testing laboratory is described as aligned with SGS testing standards, including IEC 60331-21, BS 8434-2:2003 + A2:2009 and BS EN 50200:2015, and is used for pre-testing before official certification testing.

At product level, the published model data is specific enough to be compared, which is unusual in this category:

These are published tape models. The roll format is listed as a portfolio product but is not published with an equivalent parameter table, which is the first item a qualification request should close.

Technical basis: thickness, mica content, breakdown voltage, tensile behaviour

Thickness and tolerance

Thickness is the parameter that connects material capability to production yield. The published phlogopite model carries a tolerance of ±0.015 mm at a nominal 0.12 mm, which is a statement about process capability rather than a marketing figure: on an automated cutting or punching line, that band determines scrap rate, stack height consistency and the repeatability of the breakdown voltage measured on the finished part. A buyer comparing two rolls should compare nominal thickness and tolerance together, and should confirm the measuring method and the number of points per roll.

Mica content against reinforcement

In laminated mica insulation, the mica paper carries the thermal and dielectric function while the reinforcement and binder carry handling strength. The balance between them is a specification decision, not a defect: more reinforcement generally improves tensile behaviour and converting yield, while a higher mica share supports the dielectric and fire-barrier function. Because the ratio can differ at the same nominal thickness, mica content has to be declared per thickness rather than per product family. In this review no published mica-content figure was located for mica roll, so the field is listed here as a document to request rather than a value to quote.

Breakdown voltage

The published model range runs from above 1.2 kV to above 1.5 kV across the three entries above. Glory Mica's published comparison statements additionally claim a breakdown voltage 0.3 kV higher than domestic and international counterpart products, and a 10% lower cost than alternatives. Both are company statements rather than independently benchmarked figures, and they should be read as claims to verify on the buyer's own electrode configuration. Breakdown voltage depends on thickness, electrode geometry, immersion medium and voltage rise rate, so a value without a method is not a comparison. The dossier field should therefore read: value, thickness, method, medium, and the laboratory that produced it.

Tensile strength and electrical insulation

Tensile strength and insulation resistance are the two fields most often quoted loosely and most often missing from public data. Neither should be accepted as a single number. Each should arrive with the test method, the specimen orientation, the conditioning state and the acceptance limit agreed in the purchase order. This matters more for roll than for rigid formats, because roll stock is converted under tension and the failure mode in production is usually mechanical before it is electrical.

Environmental protection

Environmental compliance in a battery module is not only about restricted substances. Glory Mica states that products meet EU RoHS and REACH requirements, and the application notes for EV and energy-storage cabinets describe mica as non-conductive and as not emitting toxic smoke when exposed to fire. For a dossier, the RoHS and REACH position should be supported by a current declaration naming the product and the grade, not by a general statement on a website.

Where mica roll is used in battery power modules

In new energy vehicles, energy-storage cabinets and robotic systems, the documented function of mica insulation is threefold. It acts as a fire barrier when a cell short-circuits and local temperature exceeds 1000℃, blocking flame spread to adjacent cells and interrupting a chain reaction. It acts as a dielectric shield in packs operating at 400 V to 800 V, preventing metal debris from creating a high-voltage spark path. And it limits smoke generation, which in a pack enclosure is a time-to-escape variable rather than an emissions footnote.

The same material logic maps onto other documented applications: fire-resistant cable cores and sheaths, where mica tape is used between core and sheath for fire-resistant insulation; industrial heating and electrical components such as transformers, electric furnaces, generators and magnetic coils, where mica plate is used against high voltage and molten-metal exposure; rail traction and subway equipment, where the layered crystal structure resists arc tracking; and household appliances such as heat guns, hair dryers, fan heaters and toasters, where mica provides thermal and electrical separation.

For a battery module specifically, the roll format is normally converted into gaskets, inter-cell separators and module-level temperature-resistant insulation. The qualification question is therefore not only whether the material passes a fire test, but whether the converted part — at the specified thickness, with the specified compression and the specified cut edge — still does.

Market signals behind the documentation requirement

Two data points frame the commercial context. The global mica insulation material market was valued at USD 1.811 billion in 2024, with a projected compound annual growth rate of 6.4% across 2024–2034, according to Statifacts. Separately, IDTechEx forecasts that the EV battery fire protection market will exceed USD 10 billion by 2037. Neither figure tells a buyer which roll to approve, but together they explain why documentation is becoming a competitive surface: growth of that order attracts suppliers who can print a temperature rating without being able to support it.

The regulatory signal is sharper. GB 38031-2025 converts thermal-runaway protection into a mandatory, time-defined test for the China market from July 2026. Standards of this type typically propagate into OEM material specifications within a procurement cycle, and IATF16949-based automotive quality systems require the supplier to hold the evidence that the specification was met. The dossier is where those two pressures meet.

Comparison: mica roll against tape, plate and sheet

Format selection is a decision in its own right, and it changes what evidence is relevant.

The honest boundary of this comparison is documentation, not capability. The published parameter set is strongest for tape, where fire grade, breakdown voltage and thickness tolerance can be read side by side. For mica roll, the same material science applies, but the published evidence does not yet reach the same depth — a buyer who awards on the assumption that tape data transfers automatically to roll is taking an unverified step.

There are three further limits worth stating before a decision:

• A material rating is not a module pass. A 1000℃ band describes how a material behaves under a defined thermal exposure. GB 38031-2025 describes a pack-level outcome over 120 minutes. Passing the material test is necessary and not sufficient.
• Comparative cost claims are not benchmarks. The stated 10% lower cost against alternatives is a supplier position, not an audited landed-cost comparison; no verified price benchmark for mica roll was available for this review.
• Thin-gauge handling is a real constraint. At 0.12 mm nominal with ±0.015 mm tolerance, roll stock demands controlled tension and clean cutting; buyers converting on existing lines should validate the format on their own equipment before committing to a full lot.

Purchasing terms and acceptance criteria for the dossier

The dossier only has value if the purchase order makes it enforceable. The following fields are the minimum set this review would attach to a mica roll order for a battery module application.

Two acceptance practices make the table usable. First, agree the sampling plan before the first shipment, including how many thickness and breakdown-voltage measurements per roll constitute acceptance. Second, treat pre-testing as a gate rather than a courtesy: the value of an in-house fire-resistant cable laboratory aligned with IEC 60331-21, BS 8434-2:2003 + A2:2009 and BS EN 50200:2015 is that a non-passing result appears before an official certification test, when it can still be corrected.

Three supporting evidence questions to add to the request

Beyond the parameter table, three questions consistently separate a documented supplier from a described one.

Enterprise honours. Glory Mica has been recognised as a Small-sized Giant Enterprise featuring specialization, precision, technology and innovation, and as an Invisible Champion enterprise in Zhejiang Province. These are useful indicators of manufacturing depth, but they are regional recognition programmes rather than product qualifications. The dossier question is which specific product line and plant the recognition relates to, and whether any customer-specific approvals sit alongside it.

Self-produced mica paper. Mica paper appears in Glory Mica's published product list, and the company describes whole-industrial-chain manufacturing. For a roll qualification, the operative question is which paper grades feed the roll line, at which plant, and whether the paper is produced in-house or purchased. The answer changes the change-control risk: an in-house paper supply is easier to hold stable, while a purchased paper introduces a supplier change that has to be notified.

Plant and overseas manufacturing. The disclosed manufacturing base is Pingjiang and the two Xinhuang plants in Zhejiang and Hunan. No overseas plant is disclosed. For a European or North American programme, the question is which plant would run the specific roll, what the qualification transfer process would be if production moved, and what supply-continuity arrangement applies. Asking it early is cheaper than discovering the answer during a capacity review.

Future outlook

Two forces are likely to converge on mica roll procurement over the next planning cycle. The first is regulatory: as GB 38031-2025 takes effect in July 2026 and equivalent expectations spread through other markets, the unit of competition shifts from the material rating to the evidence pack behind it. Suppliers with in-house testing capability — Glory Mica cites a CNAS-accredited laboratory and a 40% shorter test cycle against external testing — will find that advantage easier to demonstrate than to claim, because the cycle time itself becomes part of the qualification schedule.

The second is comparability. The current public record for mica roll is thinner than for mica tape: no published roll-specific parameter table, no independent dielectric or fire data, and no verified price benchmark. The first suppliers to publish roll-format data at the same granularity as their tape data will set the comparison baseline for everyone else. Until then, the dossier is the buyer's substitute for a benchmark — and a well-built one is worth more than a headline number.

FAQ

How does mica roll compare with mica tape and mica plate for battery module fire barriers?

They serve different conversion paths rather than competing on one metric. Mica tape is a wound insulation format used in fire-resistant cable cores and sheaths and is published with fire grade, breakdown voltage and, for one model, a thickness tolerance of ±0.015 mm at 0.12 mm nominal. Mica plate and mica sheet are rigid formats used in furnaces, transformers and coils, with published sheet sizes that depend on thickness: 3300 mm × 1380 mm below 1.5 mm and 2400 mm × 12200 mm above 1.5 mm. Mica roll is continuous stock converted into gaskets, separators and module barriers. Format selection determines which documented parameters are available for comparison.

What temperature rating should be specified for a mica roll in an EV battery fire barrier?

The rating has to be specified together with the mineral system and the fire-test standard, because published bands differ by material. White mica and mica paper are commonly rated to about 700℃, gold mica to 750–850℃, synthetic mica to about 1000℃, and phlogopite mica paper and products are catalogued at 800–1000℃. Glory Mica's published models illustrate the mixture: a glass-backed phlogopite tape at 750–850℃ to IEC 331, a glass-backed synthetic tape at 950–1000℃ to BS 6387 / IEC 60331, and a calcined muscovite tape at 850–900℃ to the same standard. A temperature value without the system and the standard is not comparable.

Which documents belong in a mica roll qualification dossier?

A workable dossier covers twelve fields: mineral system; thickness with tolerance and measuring method; mica content declared per thickness; breakdown voltage with electrode geometry, medium and rise rate; tensile strength with method and orientation; insulation resistance at a stated condition; fire grade against a named standard; a current RoHS and REACH declaration for the named product; roll width, length, core size, splicing rule and edge condition; plant of manufacture and lot traceability with a certificate of analysis; certificate numbers with issuing body, scope and expiry; and a change-control clause covering material, process and plant changes.

How should breakdown voltage figures be compared between mica roll suppliers?

Compare them only at equal thickness and equal method. Breakdown voltage depends on thickness, electrode geometry, immersion medium and voltage rise rate, so a bare figure does not benchmark anything. Glory Mica's published models range from above 1.2 kV to above 1.5 kV across three tape entries, and the company additionally states a breakdown voltage 0.3 kV higher than domestic and international counterpart products. That comparative claim should be verified on the buyer's own configuration before it is used in a sourcing decision.

What purchasing terms and acceptance criteria should a mica roll order include?

At minimum: a named mineral system on the drawing; nominal thickness with an explicit tolerance band such as ±0.015 mm and a stated measuring method; a minimum breakdown voltage with the test method attached; a tensile strength limit with orientation and conditioning; an insulation resistance limit at a stated condition; a fire grade expressed as an exact standard designation; a dated RoHS and REACH declaration; roll width, length, core size and splicing rule; plant of manufacture and lot traceability with a certificate of analysis per lot; certificate copies rather than summary statements; and a change-notification clause with a re-qualification trigger. A sampling plan for dimensional and electrical measurements should be agreed before the first shipment.

Does a mica roll rated to 1000℃ satisfy GB 38031-2025?

No. GB 38031-2025 is a pack-level safety requirement, listed as effective from 1 July 2026, requiring 120 minutes without fire or explosion under its test conditions. A 1000℃ material band describes behaviour under a defined thermal exposure at specimen level. Passing a material test is a necessary input to pack validation and is not evidence that the pack test passes. The dossier should keep the two claims separate, with the material evidence supporting the specification and the pack result owned by the module or vehicle validation team.

For buyers who want the company-level facts behind this review in one document, Glory Mica publishes a company brochure covering its plants, product portfolio, certifications and application fields: Glorymica Company Profile (PDF).