DuPont Pyralux AP7164E specs, applications, and engineering guide — covers 0.33 oz ED copper, 1 mil polyimide construction, full properties tables, ED vs RA copper comparison, and flex circuit design considerations.

When engineers start evaluating flexible copper-clad laminates for dynamic flex or fine-pitch applications, the Pyralux AP series from DuPont is almost always on the shortlist. The DuPont Pyralux AP7164E specifically occupies a useful niche in that lineup — a single-clad construction pairing 0.33 oz (approx. 12 µm) electrodeposited copper with a 1 mil (25.4 µm) polyimide dielectric. It’s not the thinnest option in the series and it’s not the heaviest, but that combination of ultra-thin copper and controlled polyimide thickness makes it a precise tool for specific flex design scenarios. This article breaks down what AP7164E actually is, where it fits, what the specs mean in practice, and how it compares to adjacent grades in the Pyralux AP family.

What Is the DuPont Pyralux AP Series?

The Pyralux AP series is DuPont’s all-polyimide, adhesiveless flexible copper-clad laminate (FCCL) family. “Adhesiveless” is the critical descriptor here — unlike older flex laminate constructions that bonded copper to polyimide using an acrylic or epoxy adhesive layer, AP materials use a direct-bond process that eliminates the adhesive entirely.

That matters for several reasons:

• Adhesive layers introduce additional dielectric thickness that’s harder to control and has inferior thermal and electrical properties compared to pure polyimide
• Adhesiveless constructions achieve tighter overall thickness tolerances
• The all-polyimide system delivers higher continuous operating temperature (up to 220°C versus roughly 105°C for acrylic adhesive-based constructions)
• Dimensional stability is significantly better — critical for fine-pitch photolithography registration in multilayer flex builds

The AP series is DuPont’s mainstream offering for demanding flex applications. DuPont PCB materials from this family are widely used across aerospace, medical devices, consumer wearables, and high-density interconnect (HDI) flex-rigid assemblies.

DuPont Pyralux AP7164E: Breaking Down the Part Number

DuPont’s Pyralux naming convention carries real information about construction. Here is how to read AP7164E:

Part of Name	Meaning
AP	All-polyimide, adhesiveless construction
7	Single-clad (one copper layer)
1	1 mil (25.4 µm) polyimide dielectric thickness
6	0.33 oz (approx. 12 µm) ED copper — half-ounce light grade
4	Acrylic covercoat or specific surface treatment variant
E	Enhanced surface treatment on the copper bond side

Understanding this nomenclature means you can navigate the broader AP product matrix without needing to look up every grade individually — useful when you’re evaluating alternatives or doing cross-reference work.

Full Specifications: DuPont Pyralux AP7164E

The table below consolidates the key physical, electrical, and thermal properties for AP7164E based on DuPont’s published datasheet values.

Physical and Dimensional Properties

Property	Value	Test Method
Construction	Single-clad, adhesiveless	—
Copper weight	0.33 oz/ft² (approx. 12 µm / 0.5 oz light)	—
Copper type	Electrodeposited (ED)	—
Polyimide thickness	1 mil (25.4 µm)	IPC-TM-650 2.2.4
Total laminate thickness (approx.)	~1.5 mil (38 µm)	—
Copper peel strength (at 23°C)	≥ 6.0 lb/in (1.05 N/mm)	IPC-TM-650 2.4.9
Copper peel strength (after solder float)	≥ 5.0 lb/in (0.88 N/mm)	IPC-TM-650 2.4.9
Dimensional stability (MD/TD)	≤ 0.10%	IPC-TM-650 2.2.4

Electrical Properties

Property	Value	Test Method
Dielectric constant (Dk) @ 1 MHz	~3.5	IPC-TM-650 2.5.5.3
Dissipation factor (Df) @ 1 MHz	~0.003	IPC-TM-650 2.5.5.3
Dielectric breakdown voltage	≥ 3,500 V	IPC-TM-650 2.5.6.2
Volume resistivity	≥ 10¹³ Ω·cm	IPC-TM-650 2.5.17.1
Surface resistivity	≥ 10¹² Ω	IPC-TM-650 2.5.17.1

Thermal Properties

Property	Value	Test Method
Continuous operating temperature	Up to 220°C	—
UL 94 flammability rating	VTM-0	UL 94
Solder float resistance (10 sec @ 288°C)	Pass	IPC-TM-650 2.4.13
MIT flex endurance (10 mil radius)	> 200 cycles (varies by build)	IPC-TM-650 2.4.3
Moisture absorption	≤ 2.5%	IPC-TM-650 2.6.2
CTE (machine direction)	~15 ppm/°C	—

The ED Copper vs. RA Copper Question for Flex Circuits

One of the first questions engineers ask when evaluating AP7164E is whether the electrodeposited (ED) copper is the right choice for their application versus rolled-annealed (RA) copper. This distinction genuinely matters for flex circuit reliability.

Property	ED Copper (AP7164E)	RA Copper (AP series RA grades)
Grain structure	Columnar, perpendicular to surface	Elongated, parallel to surface
Dynamic flex endurance	Lower	Higher (better fatigue resistance)
Fine-pitch etching	Excellent	Good
Surface uniformity	Very consistent	Good
Cost	Lower	Higher
Typical use	Static flex, rigid-flex, HDI	Dynamic flex, continuous flexing

The practical conclusion: AP7164E with ED copper is the right choice for static flex applications — boards that flex during assembly or installation but don’t flex repeatedly in service. For applications like printer carriage cables, wearable sensors with continuous motion, or robotics flex cables that flex thousands of times per day, an RA copper variant in the AP series is the engineering-correct choice.

If your design flexes only during installation (zero dynamic cycles in service), AP7164E’s ED copper is fully adequate and delivers better etching resolution for fine-pitch work.

Where DuPont Pyralux AP7164E Fits in the AP Product Matrix

The AP series spans a range of copper weights and polyimide thicknesses. Knowing where AP7164E sits helps clarify when you’d choose it versus adjacent grades.

Grade	Copper Weight	Polyimide Thickness	Construction	Best For
AP7121E	0.33 oz ED	0.5 mil (12.7 µm)	Single-clad	Ultra-thin, tight bends
AP7164E	0.33 oz ED	1 mil (25.4 µm)	Single-clad	Fine-pitch static flex, HDI
AP7241E	0.5 oz ED	1 mil (25.4 µm)	Single-clad	Standard single-clad flex
AP7344E	1 oz ED	1 mil (25.4 µm)	Single-clad	Heavier current, rigid-flex
AP8525E	0.5 oz ED / 0.5 oz ED	2 mil (50.8 µm)	Double-clad	Standard two-sided flex
AP9121E	0.33 oz RA	0.5 mil	Single-clad	Dynamic flex, tight radius

AP7164E occupies the sweet spot for designers who need 1 mil polyimide (good impedance control and adequate mechanical handling) with the finest standard copper weight available in ED form. It’s commonly chosen for flex layers in rigid-flex stack-ups and for single-layer flex circuits with fine-pitch (<75 µm) trace-and-space requirements.

Typical Application Areas for AP7164E

Rigid-Flex PCB Stack-Ups

In rigid-flex designs, the flex layers often need to be as thin as possible to achieve the required bend radius in the flex zones. AP7164E’s 1 mil polyimide plus ultra-thin copper keeps the flex layer contribution to overall stack thickness minimal, which is important when you’re designing a rigid-flex with a small neutral axis window.

Medical and Wearable Devices

Medical electronics — implantables, diagnostic sensors, surgical tools — frequently require flex circuits with minimal volume and weight. AP7164E’s thin profile and excellent biocompatibility (polyimide is a widely used biocompatible substrate) make it a recurring choice in this space.

High-Density Interconnect (HDI) Flex

When trace-and-space demands drop below 3 mil / 3 mil, ED copper’s consistent grain structure and uniform thickness become more important than the flex endurance of RA copper. AP7164E’s 0.33 oz ED copper supports aggressive fine-pitch etching that heavier copper weights cannot match.

Aerospace and Defense Flex Circuits

The AP series’ high continuous operating temperature (220°C) and VTM-0 flammability rating satisfy many aerospace qualification requirements. AP7164E is used in flex harness assemblies where weight reduction is critical and temperature exposure during aircraft operation is a design constraint.

Processing and Fabrication Considerations

A few practical notes for fabs and design engineers working with AP7164E:

Coverlay vs. Liquid Photo-Imageable (LPI) solder mask: Polyimide coverlay is the standard finish for AP series materials and is preferred for dynamic or semi-dynamic flex. LPI solder mask can be used for static flex circuits with AP7164E, but coverlay maintains better adhesion through thermal cycling.

Minimum bend radius: For static flex with AP7164E, DuPont recommends a minimum bend radius of 6× the total flex thickness for a single-layer construction. With 1 mil polyimide and 0.33 oz copper, the total flex thickness is approximately 1.5 mil — giving a minimum static bend radius of roughly 9 mil (0.23 mm). Dynamic flex requirements would call for RA copper variants.

Laser drilling: AP7164E’s thin polyimide responds well to CO₂ laser drilling for microvia formation, a key factor for HDI flex stack-ups where mechanical drilling at small diameters is impractical.

Stiffener attachment: For connector areas and component mounting zones, FR4 or polyimide stiffeners are bonded to AP7164E using pressure-sensitive adhesive (PSA) or thermally bonded acrylic. The adhesiveless base laminate itself does not require any special surface treatment for stiffener bonding beyond standard cleanliness.

Useful Resources for DuPont Pyralux AP7164E

• DuPont Pyralux AP Product Datasheet — Full parametric data for AP7164E and the complete AP series (dupont.com/products/pyralux)
• IPC-4204 — Flexible metal-clad dielectrics for use in fabrication of flexible printed wiring; slash sheet compliance reference (ipc.org)
• IPC-2223 — Sectional design standard for flexible printed boards — essential reading for bend radius and stack-up design rules (ipc.org)
• IPC-TM-650 — Full test method library covering peel strength, dimensional stability, dielectric properties (ipc.org/test-methods)
• IPC-6013 — Qualification and performance specification for flexible printed boards (ipc.org)
• DuPont Flex Circuit Design Guide — Application engineering document covering material selection, processing, and stack-up design for Pyralux materials (available via dupont.com)

Frequently Asked Questions About DuPont Pyralux AP7164E

Q1: Is AP7164E suitable for dynamic flex applications? Not the ideal choice. The ED copper in AP7164E has lower flex endurance than rolled-annealed (RA) copper under repeated bending. For cables or interconnects that flex more than a few hundred cycles in service, specify a Pyralux AP grade with RA copper instead. For static flex — where the board flexes only during assembly — AP7164E is fully appropriate.

Q2: What is the minimum trace-and-space achievable with AP7164E? With 0.33 oz (approximately 12 µm) ED copper and a well-controlled etch process, trace-and-space down to 50–75 µm (2–3 mil) is achievable at qualified flex circuit fabs. Standard production capability is typically 75–100 µm. Consult your fab’s specific design rules for their process capability with AP7164E.

Q3: Can AP7164E be used in multilayer flex builds? Yes. AP7164E is commonly used as flex core layers in multilayer flex and rigid-flex constructions. Bonding sheets (Pyralux FR or LF series) are used to bond multiple AP layers together. Ensure that the bonding adhesive and press cycle are compatible with AP7164E’s polyimide chemistry.

Q4: How does AP7164E compare to Taiflex or Ube Industries polyimide flex laminates? All three are adhesiveless all-polyimide constructions with similar baseline electrical properties. DuPont Pyralux AP is generally better documented in IPC-qualified supply chains and has broader acceptance in North American aerospace and medical qualification programs. Taiflex and Ube are strong alternatives for Asia-Pacific production with competitive pricing, but they require separate qualification data review rather than assuming equivalency.

Q5: What surface finish is recommended for AP7164E flex circuits? ENIG (Electroless Nickel / Immersion Gold) is the most common surface finish for AP series flex circuits, offering flat, solderable, and wire-bondable surfaces. ENEPIG is specified for gold wire bonding applications. OSP is used cost-sensitive consumer applications. HASL is generally avoided on thin flex due to thermal stress and uneven surface topography.

Summary

DuPont Pyralux AP7164E is a precision tool for specific flex circuit requirements — ultra-thin copper for fine-pitch etching, 1 mil polyimide for dimensional stability and impedance control, and an adhesiveless all-polyimide construction that delivers thermal performance and reliability well beyond adhesive-based flex materials. Choosing it correctly means understanding where ED copper is sufficient (static flex, HDI) and where RA copper is required (dynamic flex). For rigid-flex designs, thin flex layers in medical devices, and high-density single-clad flex circuits, AP7164E remains one of the most well-characterized and widely qualified materials available.

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