DuPont Pyralux AP9222R: The Engineer’s Complete Guide to 2 oz RA Copper / 2 mil PI Heavy Copper Flex

When a standard 1 oz flex laminate simply isn’t enough — because the current load is too high, the thermal demands too aggressive, or the design requires busbars and power traces on the same flex layer as signal routing — engineers reach for DuPont Pyralux AP9222R. This construction pairs 2 oz (70 µm) rolled-annealed copper on both sides of a 2 mil (50 µm) all-polyimide dielectric, creating a heavy copper flex laminate that can take on applications most flex substrates would fail in outright.

This guide is written from the working engineer’s perspective. It covers what the part number encodes, the full property table, why the 2 oz / 2 mil pairing is a deliberate engineering choice, where this material fits in the industrial landscape, and what you need to know before handing a design built on AP9222R to a fabricator.

What DuPont Pyralux AP9222R Part Number Tells You

DuPont’s Pyralux AP part numbering system is systematic once you understand the logic. Each segment carries a specific meaning that describes the laminate construction precisely.

Code Segment	What It Encodes	AP9222R Value
AP	All-Polyimide (adhesiveless dielectric)	All-polyimide construction
9	Double-sided copper clad	Both faces copper-clad
2	Copper foil weight code	2 oz/ft² (70 µm)
2	Dielectric thickness code	2 mil (50 µm) polyimide
2	Layer structure designator	Double-sided clad
R	Copper foil type	Rolled-Annealed (RA)

The suffix “R” is the critical differentiator from AP9222E (electro-deposited copper) and AP9222D (double-treated RA copper). For heavy current and dynamic flex applications, the R designation is the correct choice — more on why later in this article.

DuPont Pyralux AP9222R Full Technical Specifications

The following tables compile the confirmed DuPont specification data for the AP series all-polyimide double-sided laminate. The 2 oz copper / 2 mil dielectric AP9222R construction inherits the same dielectric properties as the broader AP product family, with copper-related mechanical properties scaling with the 70 µm foil.

Electrical Properties

Property	Value	Test Frequency	Test Method
Dielectric Constant (Dk)	3.4	1 MHz	IPC-TM-650 2.5.5.3
Dielectric Constant (Dk)	3.2	10 GHz	ASTM D2520
Loss Tangent (Df)	0.002	1 MHz	IPC-TM-650 2.5.5.3
Loss Tangent (Df)	0.003	10 GHz	ASTM D2520
Dielectric Strength	200 V/µm	—	ASTM D149
Volume Resistivity	>10¹⁷ Ω·cm	—	IPC-TM-650 2.5.17
Surface Resistance	>10¹⁶ Ω	—	IPC-TM-650 2.5.17
Moisture & Insulation Resistance	>10¹¹ Ω	—	IPC-TM-650 2.6.3.2

Mechanical and Thermal Properties

Property	Value	Test Method
Peel Strength (as received)	>1.8 N/mm (10 lb/in)	IPC-TM-650 2.4.9
Peel Strength (after solder)	>1.8 N/mm (10 lb/in)	IPC-TM-650 2.4.9
Tensile Modulus	4.8 GPa	IPC-TM-650 2.4.19
Tensile Strength	345 MPa	IPC-TM-650 2.4.19
Elongation	50%	IPC-TM-650 2.4.19
Flexural Endurance	6,000 cycles	IPC-TM-650 2.4.3
Glass Transition Temperature (Tg)	220°C	DuPont Method, TMA
CTE (XY-axis, below Tg)	25 ppm/°C	IPC-TM-650 2.4.41
CTE (XY-axis, above Tg)	30 ppm/°C	IPC-TM-650 2.4.41
Solder Float (288°C, 10 s)	Pass	IPC-TM-650 2.4.13
Moisture Absorption	0.8%	IPC-TM-650 2.6.2
Dimensional Stability (after etch)	±0.04 to ±0.08%	IPC-TM-650 2.2.4

Copper Foil Properties: 2 oz (70 µm) Rolled-Annealed

Parameter	2 oz RA Copper (AP9222R)	1 oz RA Copper (AP9121R)
Copper Thickness (µm)	70	35
Copper Thickness (oz/ft²)	2.0	1.0
Foil Type	Rolled-Annealed (RA)	Rolled-Annealed (RA)
Current Capacity (10mm trace, 20°C rise)	~9–11 A (external)	~6–8 A (external)
Relative Flexibility	Reduced vs. 1 oz	Higher
Grain Structure	Laminar, horizontal	Laminar, horizontal

Compliance and Certifications

Standard	Status
IPC-4204/11	Certified
UL 94	V-0 Flame Rating
UL File	E124294
RoHS	Compliant
ISO 9001:2015	Manufactured under certified QMS

Why the 2 oz / 2 mil Construction Makes Engineering Sense

At first glance, combining 2 oz (70 µm) heavy copper with a thin 2 mil (50 µm) polyimide core looks like an unusual pairing. Most engineers default to thicker dielectrics as copper weight goes up. So why does DuPont offer — and why do designers specify — this exact combination?

Current-Carrying Capacity in a Minimal Footprint

Standard printed circuit boards use copper weights ranging from 0.5 oz/ft² to 2 oz/ft², and advances in plating technology allow heavy copper features to be formed with a combination of plating and etching, resulting in straight sidewalls. At 2 oz (70 µm), the AP9222R provides double the cross-sectional copper area of a 1 oz construction. In practical terms, that means a 5 mm trace on AP9222R can carry roughly 40–50% more current than the same trace width on a 1 oz construction before hitting a given temperature rise limit — allowing designers to push more current through narrower traces, shrink flex circuit width, and reduce weight.

Thin Core Keeps the Total Assembly Compact

For high-current applications, thicker copper may be necessary to prevent overheating and ensure reliability. But using a thin 2 mil polyimide core rather than a 4 or 5 mil core keeps the total laminate stack thinner, which matters enormously in applications like wearable medical devices, drone power distribution, and satellite electronics where gram-level weight savings compound across dozens of flex layers. The 2 mil core is the thinnest practical dielectric for double-sided heavy copper work — it provides enough dielectric isolation (200 V/µm breakdown strength) while minimizing the overall assembly profile.

Thermal Management with Polyimide’s High Tg

High-power or high-temperature applications may require polyimide (Tg ~250°C) to tolerate elevated thermal stress. Pyralux AP9222R’s all-polyimide dielectric hits 220°C Tg — far ahead of standard FR4 (130°C). When 2 oz copper traces are carrying 8–12 A continuously, the self-heating in the conductor is significant. A material like FR4 would begin softening and degrading in these thermal conditions; the all-polyimide construction of AP9222R keeps the substrate dimensionally stable and structurally sound even when copper conductors run hot during sustained high-current operation.

Where DuPont Pyralux AP9222R Fits in the AP Product Family

Understanding where AP9222R sits in the full AP lineup helps designers quickly compare alternatives when the 2 oz / 2 mil specification is up for evaluation.

Standard AP Double-Sided Clad Options

Product Code	Copper (oz / µm)	Dielectric (mil / µm)	Typical Application
AP8515R	0.5 oz / 18 µm	1.0 mil / 25 µm	Ultra-fine pitch, chip-on-flex
AP9111R	1 oz / 35 µm	1.0 mil / 25 µm	High-density signal flex
AP9121R	1 oz / 35 µm	2.0 mil / 50 µm	Standard signal flex
AP9222R	2 oz / 70 µm	2.0 mil / 50 µm	Heavy current, power flex
AP9131R	1 oz / 35 µm	3.0 mil / 75 µm	Balanced flex/rigidity
AP9151R	1 oz / 35 µm	5.0 mil / 125 µm	High-frequency controlled impedance
AP9161R	1 oz / 35 µm	6.0 mil / 150 µm	High-voltage isolation

The AP9222R occupies a unique position: it is the only standard AP offering that combines heavy copper (2 oz) with a thin core (2 mil), specifically targeting high-current, space-constrained flex applications. For even heavier copper requirements (3 oz and above), DuPont offers the Pyralux AP-PLUS series, which uses thicker dielectric cores to support the added copper mass and to allow wider, more easily manufacturable trace widths for the same impedance targets.

Real-World Applications for DuPont Pyralux AP9222R

Industrial power applications require careful attention to current capacity and thermal management, and copper weights from 2 oz to 4 oz provide the cross-sectional area needed for high-current traces. For the AP9222R specifically, the following application domains appear most often.

Electric Vehicle Power Distribution

EV battery management systems, motor controller interconnects, and cell-to-bus wiring increasingly use heavy copper flex circuits. The AP9222R allows power distribution flex to be routed around battery packs and motor casings with the bendability that rigid busbar assemblies cannot achieve, while carrying the amperage that 1 oz flex cannot. Combined with the polyimide substrate’s resistance to automotive fluids and sustained temperatures, this construction handles the harsh under-hood and in-pack environment reliably.

Aerospace and Defense Power Systems

Heavy copper PCBs are used in military applications including weapons control, radar, and monitoring systems, as well as power distribution, excitation systems for power regulators, power grid switching systems, high power rectifiers, and overload relays. In aerospace platforms, the all-polyimide construction’s low outgassing and high thermal stability are as important as the current-carrying advantage. The AP9222R meets both requirements in a single laminate.

Industrial Motor Drives and Power Converters

As designers strive to obtain maximum value and performance from their projects, printed circuits are becoming more complex and are driven to higher power densities. Miniaturization, use of power components, extreme environmental conditions, and high-current requirements increase the importance of thermal management. Flex circuits built on AP9222R bridge the mechanical gap between rigid power modules and flexible cabling harnesses in servo drives, inverters, and DC-DC converter assemblies — doing the work of both a busbar and a circuit board in a single, foldable component.

Medical High-Power Imaging Equipment

MRI gradient coils, CT scanner power electronics, and ultrasound transducer drive circuits all require localized high-current flex routing within compact mechanical assemblies. The AP9222R’s combination of biocompatibility profile, high Tg, and 2 oz copper makes it a natural fit for external medical device power flex layers. (Reminder: DuPont explicitly cautions against using Pyralux AP in permanently implanted medical devices.)

Drone and UAV Power Rails

Weight per watt is a critical figure of merit in UAV design. Replacing copper wire harnesses with AP9222R-based flex power distribution reduces connector count, loom weight, and routing complexity. The 2 oz copper handles the motor ESC currents comfortably while the thin 2 mil dielectric keeps mass to a minimum.

Fabrication Considerations for Heavy Copper Flex on AP9222R

Heavy copper flex fabrication is meaningfully different from standard 1 oz flex work, and engineers should understand the implications before locking in a design.

Etching: Differential Etch Profiles Are Essential

Historically, heavy copper features were formed entirely by etching thick copper-clad laminated board material, causing uneven trace sidewalls and unacceptable undercutting. Advances in plating technology have allowed heavy copper features to be formed with a combination of plating and etching, resulting in straight sidewalls. On AP9222R, 70 µm copper requires significantly longer etch exposure times than 35 µm copper. Undercutting at the trace base is proportionally larger, which means final trace widths can be measurably narrower than the artwork dimension. Designers should discuss etch compensation with the fabricator before finalizing artwork — a common rule of thumb is to add 1× to 1.5× the copper thickness to each trace edge in the Gerber data to compensate for undercut.

Minimum Trace Width and Spacing

At 2 oz copper, minimum manufacturable trace width and spacing increase. Most qualified flex fabricators working with AP9222R target a minimum trace/space of 4–6 mil for 2 oz copper, compared to 2–3 mil achievable at 1 oz. Plan for this in your design rules from the start — attempting to route fine signal lines and heavy power traces on the same 2 oz copper layer is a yield risk.

Bend Radius: More Conservative Than 1 oz Designs

As a general rule, the bend radius should be at least 6–10 times the total thickness of the flexible PCB (including copper and substrate layers) for dynamic bending applications. With 70 µm copper on both sides of a 50 µm polyimide core, the total laminate core thickness before coverlay is already 190 µm. For static installation bends, apply a minimum bend radius of 6× total finished circuit thickness. For dynamic flex sections, use 10× or consider de-rating the copper weight in the dynamic zone only and transitioning to 2 oz in the rigid or static zones.

Coverlay Selection

Film polyimide coverlay is strongly recommended over liquid photoimageable (LPI) soldermask for AP9222R constructions. At 2 oz copper, the height differential between copper features and the base laminate surface is substantial — LPI materials struggle to fully encapsulate trace sidewalls at this copper weight, leaving voids that allow moisture ingress and reduce long-term reliability. A 1 mil or 2 mil polyimide film coverlay with acrylic adhesive conforms properly around heavy copper features.

Storage and Handling

Store AP9222R in original packaging at 4–29°C (40–85°F) and below 70% relative humidity. Do not freeze. Ensure lamination areas are well-ventilated with fresh air supply during press lamination to manage trace residual solvents from the polyimide. When drilling or routing, use adequate vacuum extraction around the drill head to minimize operator dust exposure — standard practice for polyimide flex processing.

AP9222R vs. Competing Heavy Copper Flex Laminates

Parameter	AP9222R (DuPont)	Shengyi SHE-FLEX (PI)	Ventec VT-46A (PI)
Cu Weight	2 oz / 70 µm	1–2 oz	1–2 oz
Dielectric Thickness	2 mil / 50 µm	1–4 mil	1–4 mil
Dk @ 1 MHz	3.4	~3.4–3.5	~3.3–3.5
Df @ 1 MHz	0.002	~0.003–0.004	~0.003
Tg	220°C	~220°C	~240°C
Adhesiveless	Yes	Yes	Yes
IPC 4204/11	Certified	Varies	Varies
UL 94 V-0	Yes	Yes	Yes
Brand Traceability	Full (DuPont QMS)	Factory-dependent	Factory-dependent

The DuPont AP9222R carries the brand recognition and supply chain traceability that aerospace, defense, and medical OEMs specifically require. In commercial and industrial applications where cost is the primary driver, alternative PI heavy copper laminates can be substituted — but qualification testing with the actual substrate is mandatory before production.

Sourcing DuPont Pyralux AP9222R

Pyralux AP is distributed through DuPont’s authorized laminate distribution network. For large-volume production programs, work directly with DuPont Electronics to qualify the material and establish a supply agreement. For lower-volume engineering and prototyping, qualified flex PCB fabricators typically stock or can source the material directly.

When evaluating fabricators for AP9222R-based designs, verify that they have prior experience processing 2 oz flex constructions — not just rigid heavy copper work. The film handling, etch process, and coverlay lamination for flex are substantively different from rigid PCB fabrication. DuPont PCB  is a substrate supplier worth evaluating alongside DuPont for heavy copper polyimide-based applications and rigid-flex stackup combinations.

Useful Resources for PCB Designers Working with AP9222R

Resource	Description	URL
DuPont Pyralux AP Official Page	Product overview, datasheets, contact for samples	https://www.dupont.com/electronics-industrial/pyralux-ap.html
Pyralux Laminate Product Selector	Identify custom AP product codes beyond standard offerings	https://pyralux.dupont.com
DuPont Pyralux AP Datasheet (Current)	Full TDS with construction table, properties, and certifications	https://pyralux.dupont.com
IPC-2221A	PCB design standard including trace width / current capacity guidelines	https://www.ipc.org
IPC-4204/11	Adhesiveless flexible laminate qualification specification	https://www.ipc.org
IPC-TM-650 Test Methods	Reference for all mechanical and electrical test methods cited	https://www.ipc.org
Epectec Heavy Copper Design Guide	Application-focused guide covering etch process and design rules	https://www.epectec.com/articles/heavy-copper-pcb-design.html
DuPont Pyralux AP-PLUS Datasheet	For designs requiring >2 oz copper on thicker cores	https://www.cirexx.com/wp-content/uploads/Pyralux_AP-Plus_DataSheet1.pdf

Frequently Asked Questions About DuPont Pyralux AP9222R

1. How much current can a 2 oz copper trace carry on AP9222R?

Current-carrying capacity depends on trace width, ambient temperature, allowable temperature rise, and whether the trace is on an external or internal layer. As a baseline using IPC-2221A methodology, a 5 mm (196 mil) wide external trace at 2 oz (70 µm) copper can carry approximately 9–12 A for a 20°C temperature rise above ambient at 25°C. Internal traces should be de-rated by approximately 50% compared to external layers due to reduced heat dissipation. Always run your specific geometry through an IPC-2221A calculator and validate thermally with your fabricator’s layer stackup.

2. Is DuPont Pyralux AP9222R suitable for dynamic flex applications?

Yes, with the important qualification that 2 oz copper reduces flex endurance compared to 1 oz constructions. RA copper’s laminar grain structure provides superior flex fatigue resistance compared to ED copper at the same weight, which is why the “R” suffix is specified here. For dynamic flex sections with sustained cycling (thousands of cycles), keep bend radii conservative — 10× the total circuit thickness minimum — and avoid placing via transitions or component pads within or immediately adjacent to the dynamic flex zone.

3. What is the dielectric voltage breakdown capability of the 2 mil core?

The AP polyimide dielectric delivers 200 V/µm breakdown strength. Across a 2 mil (50 µm) core, that translates to a theoretical breakdown voltage of approximately 10,000 V. In practice, working voltage limits are set at a fraction of this — typically with a safety margin of 3:1 to 10:1 depending on the application standard and required reliability level. For typical power electronics flex circuits operating below 600 V, the 2 mil core is more than adequate. For high-voltage isolation applications (>600 V), consider AP constructions with 4–6 mil dielectric thickness.

4. How does the 2 oz copper affect minimum bend radius compared to 1 oz?

Doubling copper thickness from 1 oz (35 µm) to 2 oz (70 µm) stiffens the flex section and increases the minimum safe bend radius. As a practical rule, minimum bend radius scales with total circuit thickness — and the AP9222R’s 70 µm copper per side adds substantially more thickness than 35 µm copper. In static flex applications where the circuit is bent once during installation, a minimum radius of 6× total thickness applies. For dynamic flex, use 10× minimum. If your routing requires tight bend radii, consider transitioning to 1 oz copper in the flex zone only, using a mixed-copper stackup with AP9121R in the dynamic section and AP9222R in the static power regions.

5. Can AP9222R be used in rigid-flex stackups?

Absolutely — this is one of the material’s primary use cases in power electronics rigid-flex designs. AP9222R layers function as the power distribution flex layers in a rigid-flex stackup, routed through the flex zones between rigid sections that carry control electronics, connectors, and components. The all-polyimide construction bonds compatibly with standard rigid-flex bonding films and polyimide prepregs. Work with your rigid-flex fabricator to define the correct stack sequence, bond ply selection, and controlled-depth routing parameters for the rigid-to-flex transition regions.

Summary

DuPont Pyralux AP9222R brings together two specifications that individually are well understood but rarely combined: 2 oz rolled-annealed copper and a 2 mil all-polyimide dielectric. The result is a heavy copper flex laminate that handles current loads, thermal stresses, and flex-life requirements that standard 1 oz flex laminates cannot. Its all-polyimide, adhesiveless construction gives it the thermal headroom (220°C Tg), chemical resistance, and long-term reliability that high-stakes applications in aerospace, EV power systems, industrial power conversion, and high-power medical equipment demand. If your design is pushing current through flex conductors and a standard 1 oz construction is leaving too little margin, AP9222R is the material to evaluate next.

For samples and current pricing, contact DuPont Electronics directly at pyralux.dupont.com or work with a qualified flex fabricator experienced in heavy copper polyimide processing.