DuPont Pyralux AC182500: Complete Engineer’s Guide to the 0.5 oz Cu / 1 mil PI Adhesiveless Flex Laminate

The DuPont Pyralux AC182500 sits at the heart of a large portion of the flexible circuit designs produced globally today. It’s not the thinnest laminate in the AC family, not the heaviest copper, but it’s the construction engineers reach for most often when they need a well-characterized, all-polyimide, adhesiveless single-sided flex base with standard copper weight and a full 1 mil polyimide dielectric. If you’re specifying flex materials and someone hands you a BOM with AC182500, this guide tells you everything you need to know about what you’re actually getting.

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What Is DuPont Pyralux AC182500?

DuPont Pyralux AC182500 is a single-sided, adhesiveless (two-layer) all-polyimide copper-clad laminate from DuPont’s Pyralux AC family. Unlike three-layer flex laminates that bond copper to polyimide through an acrylic or epoxy adhesive, the Pyralux AC series uses a casting process — the polyimide is cast directly onto the copper foil, eliminating the adhesive layer entirely.

Pyralux AC is a single-sided copper-clad material offered in rolls that meets IPC 4204/25, with the base polyimide cast onto the copper, allowing thinner clads than traditional manufacturing processes would allow.

The elimination of the adhesive layer is the defining characteristic of this entire product family. It directly affects thermal performance, dimensional stability, chemical resistance, and the total thickness budget of the final circuit.

H3: Decoding the AC182500 Product Code

DuPont’s AC naming system encodes the construction in the product number itself, which makes cross-referencing and substitution straightforward once you know the key:

Code Segment	Meaning	AC182500 Value
AC	All-polyimide single-sided CCL family	AC
18	Copper thickness in µm	18 µm = 0.5 oz/ft² (half-ounce)
25	Polyimide thickness in µm	25 µm = 1.0 mil
00	Second copper layer (single-sided = 00)	None
Suffix (R, RY, EM, etc.)	Copper foil type	R = Rolled-Annealed; EM = ED-M; RY = RA-Y

So AC182500R specifies RA copper; AC182500RY specifies RA-Y type copper; AC182500EM specifies ED-M electro-deposited copper. The base construction — 18 µm copper on 25 µm polyimide, adhesiveless — is the same across all suffix variants. The suffix determines copper grain structure and surface treatment, which matters for dynamic flex endurance and fine-line etching respectively.

The “double-thickness dielectric” characterization in this product’s description refers to its positioning within the AC family: compared to the 12 µm (0.5 mil) and 20 µm (0.8 mil) PI options, the 25 µm (1 mil) polyimide of AC182500 provides greater dielectric separation, better insulation resistance, and improved mechanical rigidity — the thickest standard dielectric in the core AC single-sided line.

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Full Construction Breakdown of DuPont Pyralux AC182500

H3: Layer Stack

Layer	Material	Thickness
Conductor	Copper foil (RA or ED, suffix-dependent)	18 µm / 0.5 oz/ft²
Adhesive	None — adhesiveless construction	0
Dielectric	Kapton® polyimide film (cast)	25 µm / 1.0 mil
Total laminate	—	~43 µm / ~1.7 mil

This two-layer construction contrasts directly with three-layer flex laminates like Pyralux LF or FR, where an acrylic adhesive adds 25–75 µm to the stack and introduces a thermal ceiling around 105°C. Without that adhesive, AC182500 can operate at substantially higher temperatures and offers cleaner chemical compatibility.

H3: Copper Foil Options for AC182500

The same 18 µm / 25 µm construction is offered with several copper types depending on the application:

Suffix	Copper Type	Best For
R	Rolled-Annealed (RA)	Dynamic flex, general purpose
RY	RA-Y type	Standard single-sided, excellent peel
EM	Electro-Deposited M-type	Fine-line etching, display circuits
RHA	RA-H type with additional treatment	Enhanced adhesion with bonding films

For most standard flex cable and interconnect applications, the RA variant (AC182500R or AC182500RY) is the default choice. The RA grain structure tolerates repeated bending far better than ED copper, which is the critical advantage in dynamic flex zones.

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Key Technical Properties of DuPont Pyralux AC182500

The following data is drawn from published DuPont Pyralux AC family technical datasheets. Always verify current lot-specific values against the most recent TDS from your distributor before finalizing a design.

H3: Electrical Properties

Property	Typical Value	Test Method
Dielectric Constant (1 MHz)	3.7	IPC-TM-650, Method 2.5.5.3
Dissipation Factor (1 MHz)	0.0014	IPC-TM-650, Method 2.5.5.3
Dissipation Factor (10 GHz)	0.005	—
Dielectric Strength	200 kV/mm (4.9 kV/mil)	ASTM D-149
Volume Resistivity (damp heat)	10¹⁰ MΩ	IPC-TM-650, Method 2.5.17.1
Surface Resistance (damp heat)	10⁶ MΩ	IPC-TM-650, Method 2.5.17.1

The dielectric constant of 3.7 at 1 MHz is typical for Kapton-based polyimide systems. This is not a low-loss material in the way that Pyralux TK (PTFE/polyimide composite) is, but for applications operating below a few hundred MHz — which covers a wide range of flex cable, display driver, and interconnect uses — AC182500 provides entirely adequate signal integrity performance.

The Dk at 10 GHz is 3.7 and Df at 10 GHz is 0.005, confirming the material’s suitability for moderate-frequency applications.

H3: Mechanical Properties

Property	Typical Value	Test Method
Tensile Strength	193 MPa (28 kpsi)	IPC-TM-650, Method 2.4.19
Tensile Modulus	7,580 MPa (1,100 kpsi)	ASTM D-882
Elongation	21%	IPC-TM-650, Method 2.4.19
Propagation Tear Strength	3.0 g	IPC-TM-650, Method 2.4.17.1
Initiation Tear Strength	400–700 g	IPC-TM-650, Method 2.4.16
Peel Strength (as received)	1.19 N/mm (6–7 lb/in)	IPC-TM-650, Method 2.4.9, 180°
Peel Strength (after solder)	1.19 N/mm (6–7 lb/in)	IPC-TM-650, Method 2.4.9, 180°

The maintained peel strength through soldering is one of the key practical differentiators. Polyimide-copper adhesion in adhesiveless laminates like AC182500 depends on the direct molecular bond formed during the casting process — not on an acrylic adhesive that can soften or creep under heat. This is why peel strength holds at 1.19 N/mm after a 288°C solder float, not just at ambient.

H3: Thermal Properties

Property	Value	Notes
Solder Float (10 sec, 288°C)	Pass	IPC-TM-650, Method 2.4.13
Tg (Glass Transition)	220°C	Polyimide-only, no adhesive limit
UL 94 Flammability	V-0	—
UL Maximum Operating Temp (MOT)	155°F / 68°C	UL 796 rating
CTE	19 ppm/°C	ASTM D-696
CHE (Coeff. Humidity Expansion)	8.0 ppm/% RH	—
Moisture Absorption	0.94%	IPC-TM-650, Method 2.6.2
Halogen-Free	Yes	—

The Tg of 220°C for the polyimide substrate is substantially higher than acrylic-adhesive systems, which typically operate below 150°C continuously. This matters in reflow environments, under-hood automotive exposure, and any application where the flex circuit sees periodic thermal excursions. The absence of an adhesive layer means there’s no lower-Tg phase to limit the laminate.

H3: Dimensional Stability

Condition	MD Change	TD Change
As received	Baseline	Baseline
After thermal (30 min at 200°C)	σ = 0.030%	σ = 0.026%

These values, measured on the AC182500R construction, demonstrate the low dimensional drift that makes adhesiveless AC laminates suitable for high-registration applications. When trace registration across large panel areas matters — multi-row FPC connectors, fine-pitch TAB tape, or complex multilayer buildup — the predictable, low-CTE behavior of the 1 mil polyimide base is a genuine engineering advantage over three-layer materials.

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Why Adhesiveless Matters: AC182500 vs. Three-Layer Flex Laminates

This is the question that comes up constantly in design reviews: “Can we just use Pyralux LF? It’s cheaper.” Sometimes yes. Often not. Here’s the honest comparison.

H3: AC182500 (Adhesiveless) vs. Pyralux LF / FR (Acrylic Adhesive)

Attribute	AC182500 (2-layer)	Pyralux LF / FR (3-layer)
Total thickness (0.5 oz / 1 mil PI)	~43 µm / ~1.7 mil	~93–118 µm / 3.7–4.7 mil (adds 25–75 µm adhesive)
Max continuous service temp	~220°C (PI-limited)	~105°C (acrylic-limited)
Dimensional stability	Excellent (no adhesive creep)	Good
Chemical resistance	Excellent	Good (acrylic absorbs some solvents)
IPC certification	IPC-4204/25	IPC-4204/1
Cost	Higher	Lower
Flex endurance (RA Cu)	Excellent	Good
Z-axis expansion	Lower	Higher (adhesive contributes CTE mismatch)

The table tells most of the story. If your design requires the thinnest possible total stack, elevated temperature performance, excellent chemical resistance, or long-term dimensional stability for fine-pitch applications, AC182500 is the correct starting point. If you’re building a cost-sensitive consumer flex cable that operates at room temperature in a benign chemical environment, Pyralux LF might be entirely adequate.

H3: AC182500 vs. AC182000R (0.8 mil PI Variant)

The most common intra-family comparison is between AC182500 (1 mil PI) and AC182000R (0.8 mil PI). Same copper weight, same adhesiveless construction, different polyimide thickness.

Attribute	AC182500R	AC182000R
Polyimide thickness	25 µm (1.0 mil)	20 µm (0.8 mil)
Total laminate thickness	~43 µm	~38 µm
Dielectric strength	Higher	Slightly lower
Stiffness / handleability	Slightly stiffer	More flexible
Dimensional stability	Slightly better	Good
Typical use	Standard flex, multilayer input	Thinner-profile flex, COF

The 1 mil PI of AC182500 offers better absolute insulation and is the more commonly stocked construction at distributors. The 0.8 mil variant makes sense when every micron of total thickness is being optimized in a device form factor.

H3: AC182500 vs. Pyralux AP (Adhesiveless, Double-Sided)

Pyralux AP is an all-polyimide double-sided copper-clad laminate that is the industry standard for thermal, chemical, and mechanical properties, ideal for rigid-flex and multilayer applications requiring advanced performance.

For single-sided applications, AC182500 is the right choice. For designs requiring copper on both sides, or for multilayer rigid-flex where the inner signal layers need a double-sided adhesiveless core, the AP family takes over. Think of AC as the single-sided adhesiveless workhorse; AP is its double-sided counterpart for more complex stack-ups.

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Target Applications for DuPont Pyralux AC182500

Knowing where this construction delivers maximum value versus where it’s overkill is the practical knowledge flex design engineers accumulate over years. Here’s the distilled version.

High-density single-sided flex interconnects. The standard 0.5 oz copper and 1 mil PI give fabricators plenty of copper to work with for traces carrying moderate signal or low-current power, combined with a dielectric thick enough for reliable etching and handling. This is the sweet spot for FPC cables replacing wire harnesses in consumer devices.

Dynamic flex zones. With RA copper variants (AC182500R, AC182500RY), the construction tolerates repeated bending in hinged products, printer head cables, and other mechanically active flex applications. The adhesiveless construction eliminates the failure mode of adhesive delamination under flex fatigue.

Chip-on-flex (COF) and wire bond applications. AC is an ideal material for any roll-to-roll processing, wire-bonded application, or chip-to-substrate application. The dimensional stability of the cast polyimide-copper system ensures that bond pad registration doesn’t drift during the thermal excursions of wire bonding or thermocompression bonding.

Display driver interconnects and TAB tape. Where feature dimensions are tight and registration must hold after thermal processing, AC182500’s low CTE and excellent dimensional stability make it preferred over three-layer alternatives.

Multilayer flex input layers. When single-sided inner layers feed into a multilayer flexible or rigid-flex construction, AC182500 provides a clean, adhesive-free base that bonds reliably to Pyralux AP bondply or other bonding systems without introducing incompatible adhesive materials into the stack.

Medical diagnostics. Endoscope cables, ultrasound flex arrays, and patient-contact diagnostic equipment benefit from the halogen-free composition, UL V-0 rating, and the chemical resistance that comes with an adhesiveless polyimide construction.

For design and fabrication support on DuPont PCB flex laminate materials, partnering with a fabricator who has documented experience with adhesiveless AC processing is important — the absence of an acrylic adhesive layer changes etching, coverlay bonding, and multilayer lamination process windows compared to standard three-layer laminates.

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Processing and Fabrication Considerations for AC182500

H3: Etching 18 µm Copper

At 18 µm (standard half-ounce), etching AC182500 follows conventional flex circuit processing. Unlike the ultra-thin 9 µm copper in the AC092100, there’s more process window here, and most experienced flex fabricators have validated processes for this copper weight. That said, the adhesiveless construction means there is no acrylic adhesive providing extra thickness — the total panel is thin and requires careful handling through conveyorized etch equipment.

Achievable trace/space with 18 µm copper: typically 75–100 µm (3–4 mil) line/space in volume production, with advanced shops reaching 50 µm (2 mil) line/space on well-controlled processes.

H3: Coverlay and Bonding Film Compatibility

Fabricated circuits can be cover-coated and laminated together to form multilayers or bonded to heat sinks using polyimide, acrylic, or epoxy adhesives. For coverlay bonding specifically, the polyimide surface of AC182500 benefits from surface activation before applying acrylic-based coverlays. Bond strength results vary depending on the specific bonding film and process conditions.

For pre-preg bonding in multilayer constructions, standard AC182500 requires PI surface treatment. DuPont offers Pyralux AC Plus — a surface-treated variant — specifically for pre-preg applications where higher peel strength to bonding films is needed. Using untreated AC182500 in a pre-preg stack risks inadequate inter-layer adhesion.

H3: Lamination Conditions

AC182500 is supplied fully cured. When incorporating it into multilayer constructions using bonding films or press lamination, follow the bonding film supplier’s recommended press cycle. DuPont recommends ensuring adequate ventilation in lamination areas due to trace residual solvents typical of polyimide films that may volatilize during press lamination.

H3: Drilling and Routing

Standard CNC drilling and routing apply, with the same precaution that applies to all thin flex laminates: provide adequate vacuum extraction at the drill head to control particulate. AC182500’s 1 mil PI is slightly more robust to drill entry and exit damage than 0.5 mil PI variants, but clean drill geometry and correct feed/speed parameters still matter for burr-free via formation.

H3: Storage and Shelf Life

Storage Parameter	Requirement
Temperature	4–29°C (40–85°F)
Relative Humidity	Below 70% RH
Refrigeration required?	No
Freeze allowed?	No
Shelf life (warranted)	2 years from manufacture
Packaging	Original packaging, 100% recyclable

The two-year warranty from manufacture date is contingent on compliant storage. Always record the manufacturing date from the roll label and manage FIFO (first-in-first-out) inventory to stay within the warranty window.

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Quality, Certifications, and Supply Chain

DuPont Pyralux AC182500 is manufactured under an ISO 9001:2015 certified quality system. Each manufactured lot is identified for reference traceability, and the packaging label serves as the primary tracking mechanism, including the product name, batch number, size, and quantity.

Key certifications for AC182500:

Certification	Standard	Significance
IPC-4204/25	Flexible Metal-Clad Dielectrics (Adhesiveless)	Primary laminate standard
UL 94 V-0	Flammability	Required for most end markets
UL 796	Printed Wiring Boards	UL listed
ISO 9001:2015	Quality Management System	Manufacturing facility certification
Halogen-Free	RoHS compatible	Consumer electronics, EU markets

The IPC-4204/25 slash sheet is the specific certification for adhesiveless polyimide-based single-sided clads — different from the IPC-4204/1 used for three-layer acrylic-based laminates. When writing a material specification for procurement, reference IPC-4204/25 to ensure the correct material class is supplied.

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Packaging and Sourcing Information

DuPont supplies Pyralux AC182500 through authorized global distributors. Standard roll formats:

Parameter	Standard Value
Roll widths	250 mm (9.84 in) / 500 mm (19.68 in)
Roll lengths	50 m (164 ft) or 100 m (328 ft)
Core diameter	~9.5 cm (nominal)
Custom sizes	Available by special order
Packaging	100% recyclable

Always request a Certificate of Conformance (CoC) with each shipment, including lot number, IPC slash sheet reference, and date of manufacture. DuPont maintains archive samples of each manufactured lot, which supports failure analysis if issues arise in production.

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Useful Resources for Engineers Working with DuPont Pyralux AC182500

Resource	Description	URL
DuPont Pyralux AC Datasheet (PDF)	Official TDS with full property tables	cdn-shop.adafruit.com
DuPont AP/AC Combined Datasheet	Current AC construction table incl. AC182500 variants	eurotronics.be
Insulectro Pyralux AC Product Page	Distributor with Dk/Df data and IPC slash sheet	insulectro.com/products/pyralux-ac
DuPont Pyralux Official Product Portal	Laminate product selector tool	pyralux.dupont.com
IPC-4204 Standard	Flexible metal-clad dielectric specification	ipc.org
IPC-TM-650 Test Methods	All test methods referenced in DuPont TDS	ipc.org/committee/2-10
GlobalSpec Pyralux AC Datasheet	Cross-referenced specs and distributor index	datasheets.globalspec.com
DuPont Flex Laminates Overview	Full Pyralux family product guide	dupont.com/electronics-industrial/laminates
DuPont PCB Fabrication Support	Flex circuit fabrication resources and guidance	PCBSync DuPont PCB

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5 Frequently Asked Questions About DuPont Pyralux AC182500

FAQ 1: What is the difference between AC182500R and AC182500RY?

Both are 18 µm RA copper on 25 µm polyimide, adhesiveless — the base construction is identical. The suffix indicates copper foil treatment: R is standard rolled-annealed copper; RY is RA-Y type copper with a specific surface treatment profile. In practice, RY variants are used in applications requiring verified surface roughness for plating adhesion or specific peel strength targets. For general flex cable and interconnect work, the R variant is appropriate. Confirm with your distributor which suffix is in stock for your preferred roll width before placing a production order.

FAQ 2: Can DuPont Pyralux AC182500 be used in double-sided or multilayer flex designs?

The AC182500 is a single-sided clad — copper on one side only. For double-sided adhesiveless flex, the Pyralux AP series (e.g., AP9121R: 1 oz RA / 2 mil PI, double-sided) is the correct product. However, AC182500 can be used as a single-sided inner layer in a multilayer construction by laminating two circuits face-to-face or by bonding to a Pyralux AP bondply system. In that case, polyimide surface treatment or AC Plus specification is needed to achieve adequate inter-layer peel strength.

FAQ 3: Is DuPont Pyralux AC182500 suitable for laser via formation?

Yes, laser drilling is compatible with AC182500. The 1 mil Kapton polyimide base can be ablated with CO₂ or UV lasers, and the thin 18 µm copper is within the copper removal capability of most UV laser systems. Typical via formation for COF and high-density flex applications uses UV-YAG or excimer laser sources for the cleanest via wall geometry. Confirm your laser drilling parameters with your fabricator — the adhesiveless construction means there’s no adhesive residue in the via to contend with, which actually simplifies the desmear step compared to three-layer materials.

FAQ 4: How does AC182500 perform in high-humidity environments?

The moisture absorption of 0.94% is moderate for polyimide-based materials. In applications seeing continuous high humidity (85°C/85% RH conditions typical of JEDEC moisture sensitivity testing), the material demonstrates stable electrical properties based on DuPont’s published temperature/humidity aging data at 85°C/85% RH for 2,000 hours. For applications in tropical outdoor environments, marine electronics, or humid industrial settings, the adhesiveless construction is actually an advantage — there’s no acrylic adhesive to absorb moisture and suffer hydrolytic degradation.

FAQ 5: What coverlay should I pair with DuPont Pyralux AC182500?

The most common pairing is Pyralux LF coverlay (Kapton PI film with acrylic adhesive) or Pyralux AP bondply for multilayer builds. For the cleanest all-polyimide construction — particularly where chemical resistance or high-temperature performance must be maintained throughout the circuit stack — specify Pyralux AP coverlay (adhesiveless polyimide coverlay). Note that bonding adhesiveless coverlay to AC182500 requires elevated temperatures and pressures; most flex fabricators default to acrylic coverlay for standard applications and reserve all-PI coverlay for high-reliability or high-temperature designs. Surface plasma treatment of the AC182500 PI surface before coverlay bonding consistently improves adhesion regardless of coverlay type.

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Summary: When to Specify DuPont Pyralux AC182500

Specify DuPont Pyralux AC182500 when:

• A single-sided adhesiveless flex laminate is required with standard 0.5 oz copper and the fullest standard dielectric in the AC family (1 mil PI)
• Dynamic flex performance is needed and RA copper variants (R or RY suffix) are specified
• Total laminate thickness below 50 µm is a design requirement
• Continuous service temperatures above the 105°C ceiling of acrylic-adhesive laminates are expected
• Chemical resistance matters — the adhesiveless construction withstands solvent cleaning and chemical immersion better than acrylic-based systems
• IPC-4204/25 certification is required for procurement or qualification documentation
• Chip-on-flex, wire bond, TAB, or roll-to-roll processing is the manufacturing approach
• Halogen-free material is a BOM requirement

Consider alternatives when:

• Double-sided copper is needed (→ Pyralux AP)
• Ultra-thin copper below 18 µm is required for fine-line work (→ AC092100 or AC121200)
• Budget dominates and operating temperature stays below 100°C (→ Pyralux LF)
• High-frequency performance above 5 GHz is a design requirement (→ Pyralux TK or TA)
• Multilayer double-sided core construction is the goal from the start (→ Pyralux AP family)

The DuPont Pyralux AC182500 is a mature, well-documented laminate with a long track record in demanding flex circuit applications. Its value isn’t in any single extraordinary property — it’s in the combination of good mechanical performance, stable dimensional behavior, solid thermal headroom, halogen-free composition, and the supply chain reliability of a DuPont-certified product family. Specify it correctly, process it with appropriate attention to the adhesiveless surface treatment requirements, and it will reward you with consistent yields and long-term reliability.