DuPont Pyralux AP8515E: full specs, ED vs RA copper comparison, applications in aerospace, medical, and 5G, plus fabrication tips from a PCB engineer’s perspective.
If you’ve been spec’ing flex circuit materials for any length of time, you’ve almost certainly landed on DuPont Pyralux AP8515E at some point. It sits in a particularly useful configuration within the Pyralux AP family — 1.0 mil polyimide dielectric, 18 µm (0.5 oz/ft²) electro-deposited copper, no adhesive layer. That combination hits a sweet spot for high-density flex and rigid-flex designs where you need tight dimensional control, repeatable impedance, and genuine thermal performance without the bulk and chemical limitations that adhesive-based laminates bring.
This guide breaks down everything a PCB engineer or fabricator needs to know: what the product code tells you, full material specifications, how ED copper compares to RA copper for your application, where AP8515E is being used in the real world, and what you need to know before you start processing it.
What the Part Number Actually Means
The Pyralux AP naming convention is more logical than it first looks. Once you know the decode, you can read any product code in the family at a glance.
| Code Segment | Meaning |
| AP | All-Polyimide, adhesiveless construction |
| 85 | 1.0 mil (25 µm) polyimide dielectric thickness |
| 15 | 18 µm copper foil thickness (0.5 oz/ft²) |
| E | Electro-Deposited (ED) copper foil |
| R (alternative) | Rolled-Annealed (RA) copper foil |
So AP8515E decodes to: all-polyimide, 1.0 mil dielectric, 0.5 oz ED copper. Its counterpart AP8515R shares everything except the copper type — swapping ED for rolled-annealed foil. That distinction matters quite a bit depending on what your circuit needs to do, which we’ll get into below.
DuPont Pyralux AP8515E Full Technical Specifications
Pyralux AP is an all-polyimide double-sided copper-clad laminate regarded as the industry standard in terms of thermal, chemical, and mechanical properties. Here are the key specs for the AP8515E configuration specifically:
Construction Parameters
| Parameter | AP8515E Value |
| Dielectric Material | All-polyimide (Kapton-based) |
| Dielectric Thickness | 1.0 mil (25 µm) |
| Copper Type | Electro-Deposited (ED) |
| Copper Thickness | 18 µm (0.5 oz/ft²) |
| Construction | Double-sided, adhesiveless |
| Panel Size | Up to 85 inches in length; custom sizes available |
Electrical Properties
| Property | Value | Test Method |
| Dielectric Constant (Dk) | 3.4 @ 1 MHz | IPC-TM-650 2.5.5.3 |
| Dissipation Factor (Df) | 0.002 @ 1 MHz | IPC-TM-650 2.5.5.3 |
| Dk @ 10 GHz | ~3.2 | — |
| Df @ 10 GHz | ~0.003 | — |
| Volume Resistivity | >10¹⁷ Ω·cm | IPC-TM-650 2.5.17 |
| Surface Resistivity | >10¹³ Ω | IPC-TM-650 2.5.17 |
| Dielectric Strength | >3000 V/mil | IPC-TM-650 2.5.6 |
Thermal & Mechanical Properties
| Property | Value |
| Glass Transition Temperature (Tg) | 220°C |
| Max Operating Temperature | 180°C (UL 796) |
| UL MOT Rating | 200°C |
| CTE (x/y plane) | ~12–20 ppm/°C |
| Tensile Strength (MD/TD) | ~165 / 145 MPa |
| Elongation at Break | ~70–90% |
| Peel Strength (Cu to PI) | ≥1.0 N/mm |
| Moisture Absorption | ~2.9% |
| Flammability | UL 94 V-0 |
Certifications & Standards
Pyralux AP is the premier adhesiveless copper-clad flex material certified to IPC 4204/11 and is trusted by NASA and every major defense contractor in North America.
| Standard | Status |
| IPC-4204A/11 | Certified |
| UL 94 V-0 | Listed |
| UL 796 (MOT 200°C) | Listed |
| NASA Outgassing | Data available |
| RoHS / Halogen-Free | Yes |
ED Copper vs. RA Copper: Which One Does Your Design Need?
This is the question that comes up most often when someone is deciding between AP8515E and AP8515R. They’re not interchangeable in every situation.
Adding “R” to the end of the product code specifies rolled-annealed copper foil (e.g., AP9121R), and adding “E” specifies electro-deposited copper foil.
Here’s how the two foil types compare in practical terms:
| Characteristic | ED Copper (AP8515E) | RA Copper (AP8515R) |
| Surface Roughness | Higher (matte side) | Smoother |
| Fine Line Resolution | Moderate | Better |
| Flex Endurance | Lower | Higher (better grain structure) |
| Etch Uniformity | Excellent | Good |
| Cost | Lower | Higher |
| Availability | High | High |
| Best Use Case | Static flex, rigid-flex inner layers | Dynamic flex, tight bend radius applications |
For static flex applications — panel boards that flex once during installation, rigid-flex inner core layers, or any circuit that won’t experience repeated bending — AP8515E’s ED copper is entirely adequate and often the more economical choice. The slightly rougher surface of ED foil also promotes better adhesion in some multilayer lamination scenarios.
For dynamic flex applications — circuits that flex thousands or millions of times in service (think printer heads, robotic cables, foldable device hinges) — the RA variant (AP8515R) is the right call. The rolled and annealed grain structure has significantly better fatigue resistance.
Why Go Adhesiveless? The Real Advantage of All-Polyimide Construction
Anyone who has used adhesive-based flex laminates like Pyralux LF or FR has seen the downsides: the acrylic or epoxy adhesive layer adds thickness (usually another 1–2 mils), introduces a lower-Tg weak point in the thermal profile, absorbs moisture differently than the polyimide, and can create delamination risk under aggressive thermal cycling.
Pyralux AP adhesiveless laminate was developed for high-reliability flexible and rigid circuit applications requiring thin dielectric profiles and the superior performance provided by its all-polyimide construction, enabling designers and fabricators to achieve higher density, premium performance circuitry.
In the AP8515E, the polyimide film is bonded directly to the copper foil without any adhesive intermediate. That gives you:
Thinner total stackup. At 1.0 mil dielectric + 0.7 mil copper equivalent, you’re working with roughly 1.7 mils of total clad. Adhesive-based counterparts typically add another 1–1.5 mils on each side. For multilayer flex with 4–8 signal layers, that difference accumulates fast.
Higher thermal ceiling. The Tg of 220°C applies across the full composite. With adhesive laminates, the Tg of the adhesive (often 150–170°C) is the limiting factor, not the polyimide.
Better chemical resistance. All-polyimide constructions survive the aggressive chemistry of oxide treatment, desmear, and electroless copper processes better than adhesive-based materials, where the adhesive layer can undercut or delaminate.
Consistent electrical performance. Pyralux AP does not contain glass, giving it exceptional isotropy — routed signals see the same dielectric constant regardless of which direction they travel on the circuit board. For controlled-impedance microstrip and stripline designs, that consistency is critical.
Where DuPont Pyralux AP8515E Gets Used
This material is widely used in automotive electronics, medical devices, aerospace systems, and 5G communication equipment. Let’s look at each area from an engineering standpoint.
Aerospace and Defense
Pyralux AP has been deployed on multiple planets and is trusted by NASA and every major defense contractor in North America. The low outgassing characteristic is what makes it viable for space-grade applications — organic materials that off-gas in vacuum will contaminate optical surfaces and degrade system performance. The combination of UL 94 V-0 flammability, wide operating temperature range, and IPC-4204/11 traceability also satisfies the documentation requirements of AS9100-qualified supply chains.
High-Speed and RF/Microwave Circuits
With Dk of 3.2 at 10 GHz and Df of approximately 0.003, AP8515E maintains consistent signal integrity at frequencies where most glass-reinforced laminates begin to show significant dielectric variation and increased insertion loss. The isotropic nature of the polyimide (no glass weave) means there’s no fiber weave effect — a real problem in FR4 at frequencies above 5–6 GHz.
Medical Electronics
Thin, flexible circuits built on AP8515E appear in imaging systems, catheter-based diagnostic tools, wearable monitoring devices, and surgical instruments. The material’s biocompatibility (note: not rated for permanent implantation), sterilization resistance, and dimensional stability make it suitable for the miniaturized, reliability-critical circuits these applications demand. For DuPont PCB manufacturing aimed at medical applications, AP8515E is frequently the starting specification.
Rigid-Flex Multilayer Boards
The 1.0 mil dielectric thickness is specifically useful in rigid-flex constructions where controlling the total Z-height of the flex zone is critical. Thinner dielectrics allow more signal layers within a given flex thickness while maintaining the bend radius requirements. The high material modulus provides excellent handling characteristics in a thin adhesiveless laminate, and 1 mil Pyralux AP products are fully certified to IPC-4204/11.
Automotive Electronics
In modern vehicles, flex circuits built on Pyralux AP appear in ADAS sensor modules, instrument cluster displays, transmission control units, and body control modules. The wide operating temperature range (well beyond the 125°C maximum that AEC-Q200 qualification often demands) gives automotive designers useful margin for under-hood applications.
Processing and Fabrication Notes
AP8515E processes like other Pyralux AP clads with a few things worth knowing before you run a panel:
Pyralux AP is fully cured when delivered, and lamination areas should be well ventilated with a fresh air supply to avoid buildup from trace quantities of residual solvent (typical of polyimides) that may volatilize during press lamination.
Etching: Standard cupric chloride or ammonium persulfate processes work well. The uniform thickness of ED copper produces very consistent etch rates compared to RA foil.
Drilling: Sharp carbide tools with adequate chip load are recommended. Polyimide generates stringy debris, so vacuum extraction around the drill spindle is important for clean holes and worker safety.
Storage: No refrigeration required. Store at 4–29°C (40–85°F), below 70% relative humidity, in original packaging. Shelf life is two years from shipment date under compliant storage conditions.
Oxide treatment: Fully compatible with standard black oxide and alternative oxide processes used in multilayer flex lamination.
Pyralux AP8515E vs. Other Common Configurations
| Product Code | Dielectric | Copper | Foil Type | Typical Application |
| AP8515E | 1.0 mil | 18 µm / 0.5 oz | ED | Static flex, rigid-flex cores, RF |
| AP8515R | 1.0 mil | 18 µm / 0.5 oz | RA | Dynamic flex, tight bend radius |
| AP8525R | 2.0 mil | 18 µm / 0.5 oz | RA | Standard flex, impedance-controlled |
| AP9111R | 1.0 mil | 35 µm / 1.0 oz | RA | Higher current, 1 oz standard |
| AP7163E | 1.0 mil | 9 µm / 0.25 oz | ED | Ultra-thin, high-density HDI flex |
Useful Resources for Engineers and Fabricators
- DuPont Official Product Page: dupont.com/electronics-industrial/pyralux-ap.html
- Official Technical Data Sheet (PDF): Available through DuPont’s resource center; search “Pyralux AP copper clad laminate TDS”
- IPC-4204A Standard: “Flexible Metal-Clad Dielectrics for Use in Fabrication of Flexible Printed Circuits” — available at ipc.org
- IPC-TM-650 Test Methods: Referenced throughout DuPont datasheets; free access at ipc.org/test-methods
- Insulectro Pyralux AP Distributor Page: insulectro.com/products/pyralux-ap/ — distributor with technical support resources
- NASA Outgassing Database: Pyralux AP outgassing data available via outgassing.nasa.gov
- UL Product iQ: Search “Pyralux AP” for current UL listing details at iq.ul.com
Frequently Asked Questions About DuPont Pyralux AP8515E
Q1: What does the “E” suffix mean in AP8515E, and does it affect performance?
The “E” designates electro-deposited (ED) copper as opposed to “R” for rolled-annealed (RA). ED copper is deposited electrochemically onto a carrier and has a columnar grain structure. It’s perfectly suited to static and semi-dynamic flex applications, multilayer rigid-flex inner layers, and RF designs where etch uniformity matters more than flex fatigue life. If your design requires high dynamic flex cycles, switch to the AP8515R (RA copper) variant.
Q2: Is AP8515E compatible with standard PCB fabrication equipment?
Yes. DuPont engineered the Pyralux AP series to be fully compatible with conventional PWB industry processes including wet chemistry, oxide treatment, drilling, and standard lamination presses. No specialized equipment is required beyond what a flex-capable shop already has. The material doesn’t require refrigerated storage, which simplifies logistics compared to some specialty laminates.
Q3: Can AP8515E be used for impedance-controlled circuits?
Absolutely — it’s one of the material’s strengths. The tight dielectric thickness tolerance of 1.0 mil ±10% and consistent Dk of 3.4 allow accurate impedance prediction. The all-polyimide, glass-free construction eliminates the dielectric constant variation caused by fiber weave in glass-reinforced substrates, giving you more reliable controlled-impedance performance especially at higher frequencies.
Q4: What is the minimum bend radius for AP8515E in a rigid-flex design?
For flex-to-install (static) applications using ED copper, a minimum bend radius of approximately 6× the total flex thickness is a common starting guideline, though your actual stack thickness and the number of conductive layers significantly affect this. IPC-2223 “Sectional Design Standard for Flexible Printed Boards” provides the detailed formulas. For dynamic bend applications, switch to the RA copper (AP8515R) variant and recalculate using the dynamic bend radius criteria.
Q5: How does DuPont Pyralux AP8515E compare to Taiflex or other adhesiveless flex laminates?
Pyralux AP8515E is generally considered the benchmark in the adhesiveless flex laminate category, with over 30 years of documented reliability data across demanding applications. Alternatives from Taiflex (FCCL series), Panasonic (R-F775), and Ube Industries (UPISEL-N) offer competitive electrical properties and are worth evaluating for cost-sensitive, non-critical applications. For aerospace, defense, and medical applications where material traceability, certifications, and long-term supplier stability matter, most engineers default to Pyralux AP. Always cross-check Dk, Df, Tg, and CTE values between candidate materials for your specific design requirements.
Technical data referenced in this article is based on DuPont’s published Pyralux AP technical data sheets. Always obtain the current datasheet from DuPont directly before finalizing material specifications for production.
