DuPont Pyralux LF7019R: 0.75 oz Cu / 2 mil PI — Balanced Flex Laminate for Automotive Electronics

If you’ve been specifying flex PCB materials for automotive work, you’ve almost certainly landed on the Pyralux LF family at some point. It’s been the go-to acrylic-based copper-clad laminate (CCL) for high-reliability flex circuits for over 35 years, and for good reason — consistent quality, broad fabricator familiarity, and a construction portfolio that covers a wide range of electrical and mechanical needs. The DuPont Pyralux LF7019R sits in a particularly useful spot in that portfolio: a double-sided, balanced laminate with 0.75 oz rolled-annealed (RA) copper on each side over a 2 mil Kapton® polyimide core. If you’re routing under-dash assemblies, body control module (BCM) flex harnesses, or ADAS sensor interconnects, this construction deserves a serious look.

What the Product Code LF7019R Actually Tells You

DuPont’s Pyralux LF part numbering is more logical than it first appears. Breaking it down:

Code Segment	Meaning
LF	Pyralux LF series — acrylic adhesive / Kapton® PI base
70	Copper weight designator — 0.75 oz (≈ 26 µm) per side
19	Dielectric thickness — 2 mil (50 µm) Kapton® polyimide
R	Copper type — Rolled-Annealed (RA) foil

The double-sided, balanced construction means the copper weight is equal on both sides of the polyimide core. This matters in automotive flex design because a balanced stackup minimizes residual curl and warpage — a real issue when you’re laminating at 182–199°C and then releasing tension. Unbalanced constructions (e.g., single-sided) tend to curl toward the copper side after lamination, which complicates downstream assembly, especially in automated insertion systems.

Core Technical Specifications of DuPont Pyralux LF7019R

The table below summarizes typical material properties based on published Pyralux LF data. Always verify against the current DuPont data sheet before design sign-off, as values may be revised.

Property	Typical Value	Test Method
Copper Weight (each side)	0.75 oz (≈ 26 µm)	—
Copper Type	Rolled-Annealed (RA)	—
Dielectric (PI) Thickness	2 mil (50 µm)	—
Adhesive Type	B-staged acrylic	—
Dielectric Constant (1 MHz)	3.5 max	IPC-TM-650 2.5.5.3
Dissipation Factor (1 MHz)	0.04 max	IPC-TM-650 2.5.5.3
Peel Strength (RA Cu, after solder float)	≥ 6 lb/in	IPC-TM-650 2.4.9
Dimensional Stability (MD/TD)	≤ 0.10% / ≤ 0.10%	IPC-TM-650 2.2.4
Lamination Temperature	182–199°C (360–390°F)	—
Lamination Pressure	14–28 kg/cm² (200–400 psi)	—
Lamination Time	1–2 hours at temp	—
IPC Certification	IPC-4204/1	—

The 2 mil polyimide core is one of the more popular dielectric thicknesses in the LF series for good reason — it provides enough mechanical robustness for multilayer flex and rigid-flex builds without adding unnecessary bulk. For tighter bend-radius applications, 1 mil PI is available, but the 2 mil construction in LF7019R handles dynamic flex environments better over long service life, which is exactly what automotive qualification programs demand.

Why Rolled-Annealed Copper Matters in Automotive Flex

The “R” suffix is not a small detail. RA copper starts as a solid casting that is mechanically rolled and then annealed to align the grain structure in the machine direction. The result is a fine-grained, highly ductile copper foil with dramatically superior flex endurance compared to electrodeposited (ED) copper.

In automotive applications — particularly cable replacement harnesses, door-to-body flex connectors, and under-hood sensor routing — the laminate will see thousands to tens of thousands of flex cycles over vehicle life. ED copper, with its columnar grain structure, initiates micro-cracks at grain boundaries relatively quickly. RA copper, by contrast, deforms more gracefully, redistributing strain across the grain structure before failure. For IPC-6013 Class 3 and automotive-specific qualification programs, RA copper in dynamic flex zones is essentially a baseline expectation.

The 0.75 oz weight (roughly 26 µm) is also deliberate. Going to 1 oz increases current-carrying capacity but decreases flex endurance — the thicker the copper, the stiffer the trace, and stiffness is the enemy of flex life. At 0.75 oz, LF7019R lands in a practical middle ground: enough copper cross-section for moderate current routing (think ECU signal lines, sensor buses, CAN/LIN networks) while maintaining the pliability needed for dynamic flex zones.

Balanced Construction and Automotive Stack-Up Design

The balanced double-sided construction of DuPont Pyralux LF7019R is a significant manufacturing advantage. In a 2-metal-layer flex design — common in body control and comfort system interconnects — equal copper on both faces of the PI core means that thermal and mechanical stresses during lamination are essentially symmetric. This directly reduces:

• Post-lamination curl — keeps panels flat for automated optical inspection (AOI) and registration
• Z-axis warpage in multilayer builds — critical when bonding flex layers into rigid-flex stackups
• Process scrap — balanced laminates are easier to handle through punch, drill, and plate operations

For engineers designing DuPont PCB stackups that integrate LF7019R as the core flex layer, the material is certified to IPC-4204/1 (“Flexible Metal-Clad Dielectrics for use in Fabrication of Flexible Printed Boards”), giving you a clean qualification anchor for automotive customer documentation packages.

Automotive Use Cases Where LF7019R Fits Well

The Pyralux LF series has been an industry standard in high-reliability flex applications for consumer electronics and automotive alike. The LF7019R construction specifically suits the following automotive scenarios:

Body and Comfort Electronics Seat position controllers, mirror actuators, door module interconnects, and window lift assemblies all involve flex circuits that cycle thousands of times over vehicle life. The RA copper and 2 mil PI balance durability with thin, lightweight construction.

ADAS and Sensor Interconnects Camera modules, radar sensor flex tails, and ultrasonic sensor harnesses need low-profile flex connectors with reliable impedance control. The 2 mil PI core and controlled dielectric constant (≤ 3.5) support trace impedance management at moderate signal frequencies.

Powertrain and Transmission Controls Under-hood environments expose flex circuits to thermal cycling, vibration, and chemical splash. The Kapton® polyimide core handles continuous service temperatures beyond 150°C, and the acrylic adhesive system maintains cohesive bond strength through solder float operations, a useful proxy for thermal robustness.

EV Battery Management Systems (BMS) Flat flex cables used in BMS cell interconnect boards benefit from balanced construction to avoid warpage in large-format panels. The 0.75 oz copper provides adequate current paths for cell voltage sensing while keeping the flex profile thin.

LF7019R vs. Other Common Flex Laminate Choices

Laminate	Adhesive	Cu Type	PI Thickness	Key Differentiator
LF7019R	Acrylic	RA	2 mil	Balanced DS, cost-effective for automotive flex
Pyralux LF9110R	Acrylic	RA	1 mil	Thinner, tighter bend radius, lower current capacity
Pyralux AP9121R	None (adhesiveless)	RA	2 mil	Higher thermal class, multilayer HDI, higher cost
Pyralux FR9219R	Acrylic (FR)	RA	2 mil	UL 94V-0 flame retardant rating where required
Pyralux HP series	Epoxy	RA	Various	Lower dielectric loss for RF/high-speed automotive radar

For most standard automotive signal routing and power distribution flex applications, LF7019R delivers the necessary performance at a more accessible cost than adhesiveless or epoxy-based systems. If your design moves into GHz frequencies or requires Tg well above the acrylic system’s ceiling, then Pyralux AP or HP becomes the conversation. But for the bulk of automotive interconnect work, LF7019R is a proven, fabricator-friendly choice.

Processing Considerations for Fabricators

If you’re quoting or building with LF7019R, a few process notes from the engineer’s side:

The acrylic adhesive system requires lamination at 182–199°C under 14–28 kg/cm² for one to two hours. Dwell time and pressure uniformity across large panels are critical — under-cured acrylic adhesive is a common root cause of peel strength failures in incoming QC. Confirm your press cycle is achieving temperature uniformity within ±5°C across the panel before locking the process.

Drill operations on the 2 mil PI core are straightforward. Because the acrylic adhesive is softer than the base PI, drill speed and stack height should be managed to avoid smear, particularly in blind or buried via constructions in multilayer flex builds. Desmear chemistry compatible with the acrylic system (typically permanganate or plasma) should be validated early in the process qualification.

The “R” (RA) copper surface requires that chemical treatments, oxide alternatives, or surface roughening steps are optimized for RA grain structure. RA copper has a naturally smoother surface than ED copper, which means inner-layer adhesion promoters need adequate dwell time to achieve target surface roughness (Ra) for reliable lamination adhesion in multilayer builds.

Useful Resources for Engineers Specifying Pyralux LF7019R

Resource	Description	Link
DuPont Pyralux LF Data Sheet	Official CCL spec sheet with full property tables	pyralux.dupont.com
IPC-4204/1 Specification	Flexible metal-clad dielectric standard for FPCBs	ipc.org
IPC-6013	Performance specification for flexible and rigid-flex PCBs	ipc.org
IPC-TM-650 Test Methods	Methods for peel strength, Dk, Df, dimensional stability	ipc.org
DuPont Pyralux LF Processing Guide	Lamination, drilling, plating, and fabrication parameters	Available via DuPont sales
Pyralux Safe Handling Guide	EHS guidance for handling and processing	pyralux.dupont.com
PCBSync DuPont PCB Resource	Fabrication support and material sourcing	pcbsync.com/Dupont-pcb

Frequently Asked Questions About DuPont Pyralux LF7019R

Q1: What does the “balanced” designation mean in LF7019R, and why does it matter for automotive builds?

Balanced means the copper weight is identical on both sides of the polyimide core — in this case, 0.75 oz on each face. This symmetric construction minimizes residual stress after lamination, preventing the curl or bow that single-sided or unbalanced constructions develop. In automated automotive assembly lines, flat, warp-free panels are critical for pick-and-place accuracy and AOI registration. Balanced construction also reduces internal stress in multilayer rigid-flex stackups, lowering the risk of delamination under thermal cycling.

Q2: Is LF7019R suitable for dynamic flex applications in door hinges or seat tracks?

Yes, with appropriate trace and bend-radius design. The rolled-annealed copper in LF7019R provides substantially better flex endurance than ED copper alternatives. For dynamic flex zones, maintain a minimum bend radius of 6× the total laminate thickness (a general IPC-6013 guideline), avoid traces perpendicular to the bend axis, and consider routing traces in a staggered or dispersed pattern to distribute strain. The 2 mil PI core provides a good stiffness-to-flexibility balance for moderate-cycle dynamic zones.

Q3: Can LF7019R be used in rigid-flex constructions?

Absolutely — this is one of its primary applications. The LF series is routinely used as the flex core layer in rigid-flex multilayer builds. The acrylic adhesive system is compatible with standard Pyralux LF bondply and coverlay materials, and the laminate is certified to IPC-4204/1. Process engineers should pay attention to the CTE mismatch at the flex-to-rigid transition zones and design appropriate strain relief features.

Q4: What is the maximum operating temperature for the acrylic adhesive system in LF7019R?

The Kapton® polyimide film itself can handle continuous service above 200°C, but the acrylic adhesive is the limiting element — generally rated to around 130–150°C continuous service. For under-hood applications with sustained high temperatures, consider Pyralux AP (adhesiveless) or the Pyralux HP epoxy system, both of which offer higher thermal performance. LF7019R is well-suited for cabin electronics, BMS, and powertrain control applications where temperatures remain within the acrylic adhesive’s service range.

Q5: Where can I get DuPont Pyralux LF7019R material or have boards fabricated with it?

DuPont distributes Pyralux LF materials through authorized laminators and distributors globally. For fabrication support, sourcing guidance, and technical data on DuPont PCB materials including the full Pyralux LF series, PCBSync’s DuPont PCB resource page is a useful starting point. Always request a Certificate of Conformance (CoC) and current lot data sheet when procuring laminate for automotive production programs.