DuPont Pyralux AP9232R: Engineer’s Guide to 2 oz Copper / 3 mil Polyimide for Thermal and Power Flex Boards

There is a specific class of flex circuit problem that standard 1 oz / 2 mil constructions simply cannot solve: high continuous current, aggressive thermal cycling, and a mechanical envelope that rules out rigid PCB solutions. DuPont Pyralux AP9232R — pairing 2 oz (70 µm) rolled-annealed copper with a 3 mil (75 µm) all-polyimide adhesiveless dielectric — is purpose-built for exactly that intersection. It’s a step up in both conductor mass and dielectric thickness compared to the AP9222R, and that extra 1 mil of polyimide core makes a measurable difference in fabrication yield, controlled-impedance design headroom, and thermal cycling durability.

This guide covers the construction in detail: what the part number encodes, the full specification tables, the engineering logic behind the 2 oz / 3 mil pairing, where it fits in the AP product family, real-world power flex application domains, fabrication-critical design rules, and a competitive comparison. If you’re speccing a power or thermal flex board and evaluating AP9232R, this is the engineering context you need.

Decoding the DuPont Pyralux AP9232R Part Number

DuPont’s Pyralux AP naming convention is systematic. Once you know the structure, every product code in the family is self-explanatory.

Code Segment	What It Encodes	AP9232R Value
AP	All-Polyimide, adhesiveless construction	Kapton-based, no adhesive layer
9	Double-sided copper clad	Both faces clad with copper
2	Copper foil weight designator	2 oz/ft² (70 µm) copper
3	Dielectric thickness designator	3 mil (75 µm) polyimide
2	Layer structure designator	Double-sided clad
R	Copper foil type	Rolled-Annealed (RA)

The “R” suffix is non-negotiable for power flex work. It distinguishes this from AP9232E (electro-deposited copper) and AP9232D (double-treated RA). RA copper’s horizontal grain structure delivers the flex endurance and reduced surface roughness that power flex designs require — the “E” variant is not an acceptable substitute when thermal cycling, dynamic flex, or high-frequency signals are involved.

DuPont Pyralux AP9232R Full Technical Specifications

All Pyralux AP constructions share the same all-polyimide dielectric system. Electrical properties are consistent across the 1–6 mil dielectric range. The following tables represent the current DuPont published specification data.

Electrical Properties

Property	Value	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, below Tg)	25 ppm/°C	IPC-TM-650 2.4.41
CTE (XY, 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

Construction Summary: AP9232R vs. Adjacent Constructions

Parameter	AP9222R	AP9232R	AP9242R
Copper (oz / µm)	2 oz / 70 µm	2 oz / 70 µm	2 oz / 70 µm
Dielectric (mil / µm)	2 mil / 50 µm	3 mil / 75 µm	4 mil / 100 µm
Isolation Voltage (theoretical)	~10,000 V	~15,000 V	~20,000 V
Min. Trace Width (2 oz, typical)	4–5 mil	5–6 mil	5–6 mil
Impedance Design Headroom	Moderate	Good	Better
Total Core Thickness (approx.)	190 µm	215 µm	240 µm
Flexibility	Higher	Moderate	Reduced

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 2 oz Copper and 3 mil Polyimide Is the Right Engineering Combination

The AP9232R is not an arbitrary construction. The 2 oz copper / 3 mil polyimide pairing solves a specific cluster of problems that neither thinner nor thicker variants address as well.

Current Capacity With Manageable Trace Geometry

For high-current applications, opting for 2 oz/ft² or higher improves heat spreading, and thicker copper layers reduce thermal resistance, helping to keep components cool. At 70 µm copper, the AP9232R supports trace current ratings roughly 40–50% higher than the same trace width in 1 oz copper, all else equal. That means narrower traces for the same ampacity — a direct win when the flex circuit must navigate tight bend radii or dense connector fields.

Critically, the 3 mil dielectric (vs. 2 mil in AP9222R) improves impedance design headroom. Thicker DuPont Pyralux AP cores allow copper traces with 2× greater line/space resolution to achieve identical electrical performance while greatly reducing fabrication yield loss from fine line imaging. That one extra mil of dielectric means more manufacturable trace widths for controlled impedance targets without giving up the isolation performance that power flex designs need.

Thermal Cycle Durability at the Substrate Level

High-power or high-temperature applications may require polyimide (Tg ~250°C) to tolerate elevated thermal stress. The AP9232R’s all-polyimide construction delivers 220°C Tg — far above FR4’s 130°C limit — ensuring dimensional stability and bonding integrity even when 2 oz copper conductors run hot under sustained load. With 2 oz copper plating, thermal cycle testing (25°C to 260°C) shows failure rates drop to approximately 0.6%, compared to ~32% failure with standard 1 oz copper on FR4 after eight cycles. On a polyimide substrate, that reliability advantage extends further still.

The Adhesiveless Advantage Under Thermal Stress

Adhesive-based flex laminates rely on acrylic or epoxy bondlines between copper and polyimide. Those adhesives have lower Tg values (typically 80–120°C) and degrade under sustained high-temperature or thermal cycling conditions. The AP9232R is adhesiveless — copper is directly bonded to the polyimide dielectric — which removes the weakest thermal link from the laminate stack. Adhesiveless laminates, where copper is directly bonded to the substrate, offer better flexibility and thermal performance, and are recommended for dynamic bending as they reduce the risk of delamination after thousands of flex cycles.

DuPont Pyralux AP9232R in the Full AP Product Family

Understanding where AP9232R fits helps designers quickly identify whether a step up or step down in thickness is warranted.

Standard AP Double-Sided Clad Reference Table

Product Code	Copper (oz / µm)	Dielectric (mil / µm)	Primary Application
AP9111R	1 oz / 35 µm	1 mil / 25 µm	High-density fine pitch signal flex
AP9121R	1 oz / 35 µm	2 mil / 50 µm	Standard signal flex
AP9131R	1 oz / 35 µm	3 mil / 75 µm	Balanced signal/rigidity
AP9151R	1 oz / 35 µm	5 mil / 125 µm	High-frequency controlled impedance
AP9222R	2 oz / 70 µm	2 mil / 50 µm	Ultra-compact heavy current flex
AP9232R	2 oz / 70 µm	3 mil / 75 µm	Thermal & power flex, mid-isolation
AP9242R	2 oz / 70 µm	4 mil / 100 µm	Higher isolation power flex

The AP9232R hits the middle of the 2 oz family. Against the AP9222R, it trades a small amount of total flexibility for better impedance design headroom and improved dielectric isolation. Against the AP9242R and heavier constructions (the AP-PLUS series with cores 4 mil and above), it retains more flexural capability while still handling the current and thermal demands of most power flex applications.

Real-World Applications for DuPont Pyralux AP9232R

Power and thermal flex applications show up across multiple industries. The AP9232R is particularly well suited to environments where rigid PCB solutions fail mechanically and standard 1 oz flex fails electrically.

Electric Vehicle Battery Management and Power Distribution

EV battery packs require flexible interconnects that can carry high cell-to-cell and cell-to-busbar currents while tolerating continuous vibration, thermal cycling from −40°C to +85°C or higher, and tight packaging constraints around cylindrical or prismatic cell arrays. The AP9232R’s 2 oz copper handles the continuous current demand, the all-polyimide construction withstands the thermal environment, and the flex substrate conforms to pack geometry that a rigid busbar cannot navigate. As EV manufacturing and industrial automation industries grow, manufacturers have large demands for circuit boards that can handle high power densities and intense heat generation.

Industrial Power Conversion and Motor Drives

Inverters, servo drives, and DC-DC converters increasingly use flex power circuits to bridge between power semiconductor modules and output connectors, reducing wire harness weight and improving assembly repeatability. The AP9232R’s 3 mil core provides enough dielectric isolation for the voltage rails typical in 48 V and 400 V industrial systems (well within the 200 V/µm breakdown strength of the polyimide), while the 2 oz copper handles current densities that would require impractically wide traces at 1 oz.

Aerospace and Defense Power Electronics

Military applications including weapons control, radar, monitoring systems, power distribution, excitation systems for power regulators, power grid switching systems, high-power rectifiers, and overload relays all benefit from heavy copper constructions. The AP9232R’s ISO 9001:2015 manufacturing pedigree, IPC-4204/11 certification, and full DuPont lot traceability meet the supply chain documentation requirements that defense and aerospace OEMs mandate. The low outgassing profile of the all-polyimide construction is an additional advantage in sealed enclosures and space-adjacent applications.

High-Power Medical Imaging Equipment

MRI gradient coil drivers, CT scanner power distribution flex, and high-power ultrasound transducer drive circuits all require localized heavy-current flex routing within compact mechanical frames. The AP9232R handles the current and thermal requirements while maintaining the controlled dimensions and reliability that medical OEM qualification programs demand. As always, DuPont’s explicit caution applies: Pyralux AP is not cleared for permanent human implantation applications.

LED Lighting Systems and Thermal Management Flex

High-lumen LED arrays in horticultural, industrial, and architectural lighting require flex circuits that distribute both power and thermal load simultaneously. At 2 oz copper, the AP9232R’s conductors act as both current carriers and in-plane thermal spreaders — routing heat away from LED junction sites toward heatsink attachment zones. This dual function is difficult to achieve with 1 oz copper without either running traces too hot or making them impractically wide. Thicker copper layers reduce thermal resistance, helping to keep components cool, and a standard 1 oz copper layer is insufficient for high-current applications requiring effective heat spreading.

Fabrication Design Rules for AP9232R: What You Need to Know Before Releasing Artwork

Heavy copper flex fabrication on AP9232R is not the same as 1 oz flex work or rigid heavy copper work. Engineers who treat it as either will run into yield problems.

Etch Compensation for 2 oz Copper

Historically, heavy copper features were formed entirely by etching thick copper-clad board material, causing uneven trace sidewalls and unacceptable undercutting. Advances in plating technology now allow heavy copper features to be formed with a combination of plating and etching, resulting in straight sidewalls. Even with combination plating-and-etch processes, 70 µm copper requires significantly more etch time than 35 µm copper. The practical consequence: add 1× to 1.5× the copper thickness (~70–105 µm, roughly 3–4 mil) to each trace edge as etch compensation in artwork. Confirm the exact compensation factor with your fabricator before finalizing Gerbers — it varies by shop, etch chemistry, and panel orientation.

Minimum Trace Width and Spacing at 2 oz

At 2 oz copper, plan for a minimum trace width and spacing of 5–6 mil (127–152 µm) in production-intent designs. Some shops capable of fine-feature heavy copper work can push to 4 mil, but this comes with yield risk and cost premium. Designs that try to mix sub-4 mil signal traces and 2 oz power traces on the same layer without explicit mixed-copper planning will fail — route fine signals on a separate 1 oz layer and reserve the AP9232R construction for power planes and high-current traces.

Bend Radius: Calculate from Total Finished Thickness

As a rule of thumb, the IPC-2223 standard suggests that the bend radius should be at least 10 times the thickness of the board for dynamic applications to minimize stress on copper traces. For the AP9232R, the laminate core thickness alone is approximately 215 µm before coverlay addition. Once a standard 25 µm polyimide film coverlay is added on both sides, total finished circuit thickness reaches approximately 265 µm for a bare two-layer circuit without components. Static flex minimum bend radius: 6× total thickness (~1.6 mm). Dynamic flex: 10× minimum (~2.7 mm), with 15× recommended for designs requiring >10,000 cycles.

Coverlay: Film Polyimide Is Mandatory at 2 oz

Liquid photoimageable (LPI) soldermask cannot reliably encapsulate 70 µm copper trace sidewalls. At this copper weight, the step height between trace top and base laminate surface is substantial — LPI will tent over gaps rather than filling them, leaving voids that trap moisture and create long-term reliability failures. Specify 1 mil or 2 mil film polyimide coverlay with acrylic adhesive, confirmed compatible with the AP9232R base laminate by your fabricator. For high-temperature static applications where the film coverlay will see repeated thermal cycling above 150°C, select a coverlay adhesive rated for the full operating temperature range.

Storage Requirements

Store AP9232R in original DuPont packaging at 4–29°C (40–85°F) and below 70% relative humidity. Do not freeze. Keep material flat — heavy copper laminates are more susceptible to set curl from improper storage than 1 oz constructions. Ensure lamination press areas are ventilated with fresh air to manage trace residual solvents from the polyimide during bonding cycles.

AP9232R vs. Competing Power Flex Laminates

Parameter	AP9232R (DuPont)	Shengyi SHE-FLEX 2 oz	Ventec VT-46A 2 oz	Adhesive-Based 3L Flex
Cu Weight	2 oz / 70 µm	2 oz / 70 µm	2 oz / 70 µm	2 oz / 70 µm
Dielectric (core)	3 mil / 75 µm	1–4 mil	1–4 mil	1–3 mil (PI film)
Adhesiveless	Yes	Yes	Yes	No
Dk @ 1 MHz	3.4	~3.4–3.5	~3.3–3.5	~3.5–4.2 (adhesive adds)
Tg	220°C	~220°C	~240°C	80–120°C (adhesive Tg)
IPC 4204/11	Certified	Varies	Varies	N/A (different spec)
Lot Traceability	Full DuPont QMS	Factory-dependent	Factory-dependent	Factory-dependent
UL 94 V-0	Yes	Yes	Yes	Varies

The comparison against adhesive-based flex laminates deserves extra emphasis. Three-layer flex constructions using acrylic adhesive between copper and polyimide are cheaper and widely available, but the adhesive layer’s low Tg (typically 80–120°C) becomes a failure point under the thermal cycling and sustained high-temperature conditions that power flex designs impose. For any application where the flex circuit will operate continuously above 100°C or undergo repeated thermal cycling, AP9232R’s adhesiveless construction is the correct choice, not an optional upgrade.

Sourcing and Supply Chain for DuPont Pyralux AP9232R

DuPont Pyralux AP materials are distributed through an authorized global network of laminates distributors and processed by qualified flex PCB fabricators. For engineering prototype quantities, most qualified flex shops stock the standard AP constructions or can source material within standard lead times. For production volumes, establishing a supply agreement with DuPont directly or through an authorized distributor protects your supply chain against allocation risk.

When qualifying a fabricator for AP9232R-based designs, verify specifically that they have prior production experience with 2 oz flex constructions — not just rigid heavy copper work and not just standard 1 oz flex. The combination of heavy copper and flex substrate requires process experience in both domains simultaneously. DuPont PCB  is one established substrate supplier worth evaluating alongside DuPont Pyralux AP for heavy copper and power-oriented rigid-flex stackup combinations.

Useful Resources for Power Flex Designers

Resource	Description	URL
DuPont Pyralux AP Official Product Page	Overview, datasheets, and DuPont contact for samples	https://www.dupont.com/electronics-industrial/pyralux-ap.html
DuPont Pyralux Laminate Product Selector	Identify product codes for custom AP constructions	https://pyralux.dupont.com
DuPont Pyralux AP Datasheet (Current, PDF)	Full TDS including all standard construction options	https://insulectro.com/wp-content/uploads/2021/09/EI-10124-Pyralux-AP-Data-Sheet.pdf
DuPont Pyralux AP-PLUS Datasheet	For designs requiring >2 oz copper or core >6 mil	https://www.cirexx.com/wp-content/uploads/Pyralux_AP-Plus_DataSheet1.pdf
Epectec Heavy Copper PCB Design Guide	Detailed etch compensation, design rules, and thermal cycle data	https://www.epectec.com/articles/heavy-copper-pcb-design.html
IPC-2221A PCB Design Standard	Trace width / current capacity methodology	https://www.ipc.org
IPC-2223 Flex PCB Design Standard	Flex-specific design rules including bend radius guidelines	https://www.ipc.org
IPC-4204/11 Laminate Qualification Spec	Adhesiveless flexible laminate qualification standard	https://www.ipc.org
IPC-TM-650 Test Methods Database	Full library of test methods cited in laminate datasheets	https://www.ipc.org/TM

Frequently Asked Questions About DuPont Pyralux AP9232R

1. How does the 3 mil core on AP9232R improve on the 2 mil core of AP9222R for power flex?

The extra 1 mil of dielectric thickness delivers three concrete improvements. First, theoretical isolation voltage increases from approximately 10,000 V to 15,000 V, giving more working voltage margin for power electronics applications in the 400–600 V range. Second, controlled impedance modeling becomes more forgiving — wider, more manufacturable trace widths achieve the same impedance on a 3 mil core, improving fabrication yield for designs that include signal routing alongside power traces. Third, the slightly increased total laminate stiffness improves handling during fabrication, reducing the risk of wrinkle or set in the panel during multiple lamination and processing cycles.

2. What continuous current can a 10 mm wide trace carry on AP9232R?

Using IPC-2221A methodology for a 10 mm (394 mil) wide external trace in 2 oz (70 µm) copper with a 20°C temperature rise at 25°C ambient, typical current capacity is approximately 14–18 A depending on surface finish, trace geometry, and thermal environment. Internal traces in a multilayer construction should be de-rated by approximately 50% compared to external layer values due to reduced convective cooling. Always validate trace current ratings against your actual thermal boundary conditions — the IPC-2221A nomograph is a starting point, not a guarantee.

3. Is DuPont Pyralux AP9232R suitable for applications that cycle between −40°C and +125°C?

Yes. The all-polyimide construction’s 220°C Tg and 25 ppm/°C XY CTE provide excellent stability across a −40°C to +125°C operating range. The key requirement is ensuring all other materials in the assembly — coverlay adhesive, bondplies, and any stiffeners — are also rated for the full temperature range. Acrylic adhesive coverlays typically perform well through +125°C. For continuous operation above +150°C, verify coverlay adhesive ratings with your material supplier, and consider epoxy-based adhesive alternatives for extreme thermal applications.

4. Can AP9232R layers be used in a rigid-flex stackup alongside standard 1 oz signal flex layers?

Absolutely, and this is one of the most practical applications for the construction. In a power rigid-flex design, AP9232R layers serve as the dedicated power distribution layers — routed through flex zones between rigid sections carrying control electronics and connectors. The all-polyimide construction is fully compatible with standard rigid-flex bonding films and polyimide prepregs used in the rigid sections. The laminate’s CTE closely matches the rest of the polyimide-based stackup, minimizing differential thermal expansion stress at rigid-to-flex transitions. Discuss ply sequence and controlled-depth routing parameters with your fabricator early in the design cycle.

5. How does the AP9232R’s polyimide dielectric compare to FR4 for thermal management flex?

The comparison is significant. FR4’s glass transition temperature of ~130°C means it starts softening at temperatures that 2 oz copper power traces can produce under sustained load. FR4 also has lower thermal conductivity (~0.25 W/m·K) compared to polyimide (~0.5 W/m·K), though neither is a particularly efficient thermal spreader — the primary thermal path in both constructions is through the copper conductors themselves. The critical advantage of AP9232R’s polyimide is dimensional and structural stability under thermal cycling: it does not soften, delaminate, or lose peel strength in the operating range that power flex applications impose on it. FR4 cannot be used in flex applications anyway — it fractures under bending — making the comparison academic for any design requiring a compliant mechanical substrate.

Summary

DuPont Pyralux AP9232R occupies a well-defined position in the power flex materials landscape: 2 oz rolled-annealed copper for genuine high-current capability, combined with a 3 mil all-polyimide adhesiveless core that delivers isolation headroom, impedance design flexibility, and thermal cycle durability that thinner-core constructions cannot match. Its adhesiveless construction removes the weak thermal link present in three-layer acrylic-adhesive flex laminates. Its full IPC-4204/11 certification and ISO 9001:2015 manufacturing pedigree meet the documentation requirements that aerospace, defense, medical, and automotive OEM programs demand. If your power flex design needs more than a 2 mil core provides and you’re not yet ready to step up to the AP-PLUS family, AP9232R is the construction to evaluate.

For samples and engineering support, contact DuPont Electronics at pyralux.dupont.com or engage a qualified flex fabricator with demonstrated 2 oz construction experience.