Complete guide to DuPont Pyralux FR9110E — 1 oz ED copper / 1 mil FR acrylic / 1 mil Kapton flex laminate. Learn when to use ED over RA copper, UL94 VTM-0 and UL796 certifications, full property data, FR9110E vs FR9110R comparison table, applications, and 5 FAQs.
There’s a conversation that happens regularly in flex PCB design reviews, and it usually goes something like this: the engineer specifies FR9110R by default because that’s what they’ve always used, the buyer notices the ED version is cheaper, and someone has to decide whether the cost difference is worth investigating. DuPont Pyralux FR9110E is not a second-rate version of FR9110R — it is a deliberately different copper foil specification applied to the same flame-retardant, polyimide-based flex substrate. Knowing when the ED variant is the correct call, rather than a compromise, is genuinely useful engineering knowledge.
This guide covers the confirmed construction data, the FR series’ unique flame-retardant credentials, the real engineering tradeoffs between electro-deposited and rolled-annealed copper, and the specific design scenarios where FR9110E outperforms or is the better choice over FR9110R.
What Is DuPont Pyralux FR9110E?
DuPont Pyralux FR9110E is a single-sided, flame-retardant, acrylic-based copper-clad laminate from DuPont’s Pyralux FR family. Confirmed construction from DuPont’s official datasheet (H-73233):
- Copper foil: 1 oz/ft² (305 g/m²) — electro-deposited (ED), indicated by the “E” suffix
- Adhesive: 1 mil (25 µm) — proprietary flame-retardant C-staged acrylic
- Dielectric: 1 mil (25 µm) — DuPont Kapton® polyimide film
- IPC Certification: Yes — certified to IPC-4204/1
The “FR” designation is the critical differentiator from the otherwise similar LF series. Where Pyralux LF uses a standard modified acrylic adhesive, the FR series uses a flame-retardant acrylic adhesive that gives the laminate a UL94 VTM-0 flammability rating and UL796 Direct Support compliance — certifications that are mandatory in specific regulatory contexts and simply unavailable in the LF family.
The “E” suffix is equally significant. FR9110E and FR9110R are the same construction in every respect except copper foil type. FR9110R uses rolled-annealed (RA) copper; FR9110E uses electro-deposited (ED) copper. That single variable controls the mechanical fatigue behavior of the finished circuit, the fine-line etching capability, and the material cost — and it determines whether your design actually needs one or the other.
FR9110E Construction Breakdown
Layer-by-Layer Stack
| Layer | Material | Thickness (mil) | Thickness (µm) |
| Copper Foil | Electro-Deposited (ED) Copper | ~1.4 mil | ~35 µm |
| Adhesive | Flame-Retardant C-staged Acrylic | 1.0 mil | 25 µm |
| Dielectric | DuPont Kapton® Polyimide Film | 1.0 mil | 25 µm |
| Total Nominal Build | Single-Sided Clad | ~3.4 mil | ~85 µm |
Decoding the FR9110E Product Code
| Code Segment | Meaning |
| FR | Flame-Retardant Pyralux series |
| 9 | Standard copper weight base group |
| 1 | 1 oz copper weight |
| 1 | 1 mil Kapton® dielectric thickness |
| 0 | 1 mil adhesive thickness designator |
| E | Electro-Deposited (ED) copper foil |
Substituting “R” for “E” gives you FR9110R (rolled-annealed copper). Substituting “D” gives FR9110D, which is double-treated RA copper where nodules of electro-deposited copper are applied to both surfaces of the RA foil — this eliminates some surface preparation steps before resist or coverlay lamination.
Confirmed Performance Properties of Pyralux FR9110E
All property data below is reported for the standard reference construction of 1 oz copper / 1 mil adhesive / 1 mil Kapton and applies equally to FR9110E (ED copper) and FR9110R (RA copper), since the base laminate properties are driven by the adhesive and dielectric rather than copper foil type. Copper-type-specific differences are addressed in the section that follows.
Flammability and UL Certifications
| Property | Value | Test Method |
| Flammability Rating | VTM-0 | UL94 |
| Meets UL796 Direct Support Requirements | Yes | UL796 |
The VTM-0 rating is specifically the thin-film variant of the UL94 vertical burn classification — the appropriate rating for flexible polyimide films that cannot be tested in the standard V-series configuration. VTM-0 is the strictest thin-film classification: samples must self-extinguish rapidly, with no flaming drips. This is the rating required for any flex circuit that must carry a UL mark in the finished product.
The Pyralux FR series does NOT contain polybrominated biphenyls (PBBs), polybrominated biphenyl oxides (PBBOs), or polybrominated diphenyl ethers (PBDEs) — a critical declaration for RoHS compliance and environmental certification.
Electrical Properties
| Property | Typical Value | Test Method |
| Dielectric Constant (Dk) @ 1 MHz | 3.5 | IPC-TM-650 2.5.5.3 |
| Dissipation Factor (Df) @ 1 MHz | 0.02 | IPC-TM-650 2.5.5.3 |
| Dielectric Strength | 137 kV/mm (3,500 V/mil) | ASTM D-149 |
| Insulation Resistance (ambient) | 10⁶ megohms | IPC-TM-650 2.6.3.2 |
| Volume Resistivity (ambient) | 10⁹ megohm-cm | ASTM D-257 |
| Surface Resistance (ambient) | 10⁷ megohms | ASTM D-257 |
Mechanical and Adhesion Properties
| Property | Typical Value | Test Method |
| Peel Strength — After Lamination | 2.1 N/mm (12 lb/in) | IPC-TM-650 2.4.9 |
| Peel Strength — After Soldering | 1.9 N/mm (11 lb/in) | IPC-TM-650 2.4.9 |
| Solder Float Resistance (288°C, 10 s) | Pass | IPC-TM-650 2.4.13 |
| Dimensional Stability (MD/TD) | −0.10% | IPC-TM-650 2.2.4 |
| Thickness Tolerance | +10% | IPC-TM-650 4.6.2 |
The peel strength of 2.1 N/mm (12 lb/in) after lamination is notably higher than the LF series’ 1.8 N/mm (10 lb/in), which is one of the practical benefits of the FR adhesive formulation. With a UL Maximum Operating Temperature (MOT) of 105°C, the FR series has a defined thermal use limit that qualifies it for most consumer electronics, automotive interior, and industrial control applications.
Lamination Processing Window
Laminating conditions for Pyralux FR flexible composites are identical to those for the LF series: part temperature 182–199°C (360–390°F), pressure 14–28 kg/cm² (200–400 psi), time 1–2 hours at temperature. Pyralux FR can be processed like Pyralux LF, which means any fab that runs LF can run FR without equipment changes or separate process qualification.
The Core Decision: FR9110E vs. FR9110R
ED Copper vs. RA Copper — What the Grain Structure Actually Means
This is the engineering heart of the FR9110E vs. FR9110R decision, and it’s worth understanding at the microstructural level.
Rolled-annealed copper is produced by rolling thick copper ingots repeatedly, then annealing to relieve internal stress. The result is a horizontal, lamellar grain structure — grains lying parallel to the foil plane. RA copper can elongate 20–45% before fracture, giving it exceptional resistance to cyclic fatigue stress. When a flex circuit bends repeatedly, RA copper’s grain planes slide relative to each other, absorbing strain without initiating cracks. This is why RA copper is mandatory for any flex circuit that will be bent more than a handful of times in service.
Electro-deposited copper is grown electrochemically on a rotating cathode drum. The result is a columnar, vertical grain structure — grain boundaries running perpendicular to the foil plane, like a stack of vertical pillars. ED copper elongates only 4–11% before fracture. Under repeated bending, these vertical grain boundaries become crack initiation sites. A flex circuit built on ED copper and repeatedly bent will fail at the copper layer significantly faster than one using RA copper.
The practical implication is unambiguous: ED copper is for static flex applications, RA copper is for dynamic flex applications. Static flex means the circuit is bent once during assembly and never moves again. Dynamic flex means the circuit bends repeatedly during service life.
Head-to-Head Property Comparison: FR9110E vs. FR9110R
| Property | FR9110E (ED Copper) | FR9110R (RA Copper) |
| Copper foil type | Electro-Deposited | Rolled-Annealed |
| Grain structure | Columnar/vertical | Lamellar/horizontal |
| Elongation before fracture | 4–11% | 20–45% |
| Dynamic flex fatigue life | Low — static use only | High — suitable for dynamic flex |
| Fine-line etch capability | Better (sharper edges) | Slightly softer edge definition |
| Surface roughness (treated side) | Slightly rougher | Smoother |
| High-frequency insertion loss | Marginally higher | Marginally lower |
| Material cost | Lower | Higher |
| Construction | 1 oz / 1 mil adhesive / 1 mil PI | 1 oz / 1 mil adhesive / 1 mil PI |
| Flammability | VTM-0 (UL94) | VTM-0 (UL94) |
| IPC Certification | IPC-4204/1 | IPC-4204/1 |
When to Choose DuPont Pyralux FR9110E Over FR9110R
The question in the title deserves a direct answer with real engineering criteria, not hedging. Here are the scenarios where FR9110E is the correct specification:
Static Flex Applications That Require UL Flame Retardancy
This is the primary use case. If your circuit will be bent once during installation — routed through an enclosure, folded into a module, formed around a housing — and then permanently fixed, RA copper’s dynamic flex advantage is irrelevant. ED copper performs equally well in static flex applications. Choosing FR9110E over FR9110R saves material cost without sacrificing any performance that the application actually demands.
For designs where a UL listing on the finished product requires the flex circuit to carry a VTM-0 material rating — consumer appliances, power conversion equipment, industrial control panels — FR9110E delivers both the flame-retardant credential and the lower copper cost of ED foil.
Fine-Pitch and High-Density Trace Designs
ED copper’s columnar grain structure dissolves more uniformly during chemical etching than RA copper’s layered structure. This gives ED copper a sharper circuit edge profile — circuit trace sidewalls approach vertical rather than showing the slight undercut common in RA copper etching. For designs targeting line/space below 75 µm (3 mil), or for chip-on-flex (COF) configurations where trace edge definition is critical, FR9110E’s ED copper etching behavior can improve yields and reduce fine-pitch defects compared to FR9110R.
Cost-Sensitive Programs with No Dynamic Flex Requirement
RA copper is more expensive to produce than ED copper, with the cost premium increasing as foil thickness decreases. In high-volume programs — consumer devices, white goods, automotive interior electronics — where tens of thousands of panels are being processed and the design uses static flex exclusively, specifying FR9110R instead of FR9110E is simply paying for a performance property the circuit will never use. FR9110E is the right economic call in these cases, provided the application genuinely has no dynamic flex requirement.
Rigid-Flex Constructions Requiring FR Rating
In rigid-flex designs, the flex portions that are laminated between rigid sections typically see no dynamic bending in service — they’re permanently encased. The FR rating on the flex material may be needed to satisfy UL certification of the overall assembly. FR9110E gives you the flame-retardant flex substrate with ED copper’s etching advantages for the fine-feature patterns that often appear in rigid-flex inner layers.
When FR9110R Is the Right Choice Instead
To be complete about this: if your design has any meaningful dynamic flex requirement, FR9110R is the only responsible specification. Dynamic flex includes display hinges, robotics arm flex interconnects, wearable device articulation zones, cable replacement flex that flexes during installation, and any application where IPC-2223 dynamic flex categories apply. ED copper in a dynamic flex design is an eventual field failure waiting to happen, and the cost saving on material is not worth it.
<image alt=”Pyralux FR Flex Laminate Applications” src=”placeholder”>
Typical Applications for DuPont Pyralux FR9110E
Consumer Electronics Assembly Flex — Camera module interconnects, display flat flex cables in laptop/tablet hinges that are bent once and fixed, and backlight driver flex assemblies. These are static flex applications, often in products requiring UL listing, making FR9110E a natural fit.
Industrial Control Panels and Power Supplies — UL796 compliance is a direct requirement for flex circuits used in power supply construction per UL796’s “Direct Support” category. FR9110E’s VTM-0 rating and UL796 certification make it the correct grade where LF9110E — a non-FR grade — cannot be used.
Automotive Interior Flex Wiring — Static flex interconnects in dashboard electronics, climate control panels, and lighting control modules. <link href=”https://www.raypcb.com/Dupont-pcb/”>DuPont PCB</link> materials including the Pyralux FR family are used across automotive electronics supply chains where halogen-free, flame-retardant flex substrates are standard procurement requirements.
Multilayer Rigid-Flex Inner Layers — FR9110E is commonly used as core material in rigid-flex constructions where the flex layer requires flame retardancy certification and the design does not involve dynamic bending.
Medical and Test Equipment Wiring Flex — Static flex cable replacements in diagnostic equipment, test fixtures, and laboratory instruments. Note that DuPont’s caution against use in permanent human implant applications applies to the entire FR family.
FR9110E in Context: Neighboring Constructions
Single-Sided FR Constructions with the Same Adhesive/Kapton Thickness
| Product Code | Copper (oz) | Adhesive (mil) | Kapton (mil) | Copper Type | IPC Cert |
| FR9110E | 1.0 | 1.0 | 1.0 | ED | Yes |
| FR9110R | 1.0 | 1.0 | 1.0 | RA | Yes |
| FR8510R | 0.5 | 1.0 | 1.0 | RA | Yes |
| FR7031R | 0.75 | 1.0 | 1.0 | RA | Yes |
| FR9120R | 1.0 | 1.0 | 2.0 | RA | Yes |
| FR9210R | 2.0 | 1.0 | 1.0 | RA | Yes |
Note: The majority of FR constructions are listed in DuPont’s datasheet with the RA “R” suffix as the default. ED versions are available by substituting “E” for “R” in the product code. Always confirm availability for your specific construction with your distributor.
Quality, Traceability, and Storage
FR9110E is manufactured under DuPont’s ISO 9001:2015 Quality Management System. A Certificate of Conformance is available for every batch. Complete material and manufacturing records for each lot, with archived samples of finished laminate, are retained for reference. Roll labels carry the lot number, DuPont order number, customer order number, IPC specification, customer specification, and customer part number — retain these for any downstream quality or audit inquiry.
Store FR9110E in original packaging at 4–29°C (40–85°F), below 70% relative humidity. No refrigeration is required. The two-year warranty from shipment date applies when these storage conditions are maintained. As with all acrylic-adhesive flex materials, bake material that has been exposed to elevated humidity conditions before lamination to prevent voiding.
Useful Resources for Engineers Working with DuPont Pyralux FR9110E
| Resource | Description | Link |
| Pyralux FR CCL Datasheet (H-73233) | Official DuPont FR copper-clad laminate datasheet — full construction tables and properties | via Epectec |
| DuPont Pyralux FR Product Page | FR family overview: laminates, coverlays, bondply, sheet adhesives | dupont.com/pyralux-fr |
| DuPont Pyralux Product Portal | Product selector, processing guides, safe handling documentation | pyralux.dupont.com |
| Insulectro Pyralux FR Page | Distributor overview of FR family with UL MOT reference | insulectro.com |
| IPC-4204/1 Standard | Specification for flexible metal-clad dielectrics for flexible printed wiring | IPC.org |
| IPC-TM-650 Test Methods | Complete test method manual referenced in FR property tables | IPC.org/TM-650 |
| IPC-2223 Flexible Circuit Design Standard | Design standard for flexible printed boards including dynamic flex guidelines | IPC.org |
| UL 94 Standard | Flammability of Plastic Materials — reference for VTM-0 and V-series ratings | UL.com |
Frequently Asked Questions
Q1: What is the difference between VTM-0 and V-0, and which applies to FR9110E?
Both are UL94 flame-retardancy classifications, but they apply to different specimen geometries. V-0 applies to specimens thick enough to stand vertically on their own for the burn test (typically ≥0.75 mm). VTM-0 — the “Very Thin Material” category — applies to thin films and flexible materials that cannot support themselves vertically, which describes flex circuit laminate correctly. Both ratings indicate that the material self-extinguishes rapidly with no flaming drips; VTM-0 is simply the appropriate version of that standard for films. FR9110E carries VTM-0, which is the correct and most demanding thin-film flammability classification available.
Q2: Can I substitute FR9110E for LF9110E in a design to get the FR rating?
Yes, and this is exactly the intended use case for the FR family. Pyralux FR processes identically to Pyralux LF — same lamination temperatures, same pressures, same cycle times — so a grade substitution from LF9110E to FR9110E requires no changes to fabrication parameters. The only differences are the flame-retardant adhesive (which gives VTM-0 and UL796 compliance) and the slightly higher peel strength (2.1 N/mm vs. 1.8 N/mm). If your product qualification requires a UL listing that mandates VTM-0 flex material, this substitution is the path forward.
Q3: Does the ED copper in FR9110E affect high-frequency performance compared to FR9110R?
Marginally, yes. The treated side of ED copper foil is slightly rougher than RA copper, which increases conductor surface roughness and therefore skin-effect losses at high frequencies. For most flex circuit applications in the sub-6 GHz range, this difference is negligible. It becomes more meaningful above 10 GHz, where signal attenuation from conductor roughness is a first-order concern. For controlled-impedance flex in consumer RF bands (2.4 GHz, 5 GHz), FR9110E and FR9110R will perform essentially identically. For mmWave or microwave flex above 10 GHz, FR9110R’s RA copper (or an adhesiveless AP construction) is preferable.
Q4: How do I know if my flex design is “static” or “dynamic” for the purpose of choosing FR9110E vs. FR9110R?
The IPC-2223 standard defines flex categories. For practical purposes: if the flex circuit will be bent fewer than approximately 100 times over its entire service life — including assembly, installation, and any field servicing — it can be treated as static, and ED copper (FR9110E) is acceptable. If the circuit will flex continuously or cyclically during operation — display hinges, articulating joints, conveyor monitoring cables, wearable flex zones — it is dynamic and requires RA copper (FR9110R). When in doubt, a conservative default to FR9110R for any design where bending will occur more than a few times is prudent. The cost premium for RA copper is far less than the cost of a field failure.
Q5: Is there a double-sided equivalent of FR9110E?
Yes. The double-sided FR equivalent is FR9111E (1 oz ED copper on both sides / 1 mil adhesive / 1 mil Kapton). The “R” variant is FR9111R. The double-sided FR family follows the same naming convention as the single-sided series, with the last digit incrementing to designate double-sided construction. As with the single-sided grade, the ED versus RA copper choice carries the same application-dependency: static flex or fine-pitch work can use ED copper; anything with dynamic flex requirements must use RA.
Final Thoughts on Specifying DuPont Pyralux FR9110E
DuPont Pyralux FR9110E is a well-defined material that earns its place in the design toolkit when the application genuinely calls for what it delivers: UL94 VTM-0 flammability, UL796 Direct Support compliance, IPC-4204/1 certification, and ED copper’s fine-line etching advantages — all in a static flex application. It is not a cheaper workaround for FR9110R and should never be specified where dynamic flex will occur. It is, however, the right specification for a large category of flex circuit designs where UL certification is mandatory and repeated bending is simply not in the application profile.
If you’re evaluating whether FR9110E is the correct grade for your program, the starting questions are: Does the flex circuit move in service? Does the product need a UL listing that requires VTM-0 flex material? Does the design have fine-pitch features that would benefit from ED copper etching characteristics? If the answers are no, yes, and yes — FR9110E is your grade.
All property data is sourced from DuPont’s published technical datasheet for Pyralux FR Copper-Clad Laminates (H-73233). Typical values may vary depending on construction and processing conditions. Consult DuPont’s technical resources or a qualified distributor before finalizing material selection for production.
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Complete guide to DuPont Pyralux FR9110E — 1 oz ED copper / 1 mil FR acrylic / 1 mil Kapton flex laminate. Learn when to use ED over RA copper, UL94 VTM-0 and UL796 certifications, full property data, FR9110E vs FR9110R comparison table, applications, and 5 FAQs.
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