Full engineering guide to DuPont Pyralux LF9150R: construction specs, controlled impedance design advantages, comparison vs LF9110R and LF9120R, application guidance, and 5 FAQs from a PCB engineer’s perspective.
When engineers first pull up the Pyralux LF selection table and spot DuPont Pyralux LF9150R, the reaction is usually the same: why would anyone need 5 mil of Kapton? That’s a fair question ¡ª most single-sided flex constructions live comfortably in the 1-to-2 mil Kapton range, and the jump to 127 ?m (5.0 mil) of polyimide feels like a lot. But there are real engineering reasons to reach for this specific laminate, and understanding those reasons is what this article is about.
This guide covers the complete construction specs, electrical and mechanical properties, where LF9150R fits in the broader Pyralux LF family, and exactly when a thick-Kapton construction earns its place in a flex or rigid-flex stackup. If you’ve been speccing DuPont PCB flex laminates and wondering whether the 5 mil variant makes sense for your design, read on.
What Is DuPont Pyralux LF9150R?
DuPont Pyralux LF9150R is a single-sided, acrylic-based copper-clad laminate from the Pyralux LF product family. It bonds rolled annealed (RA) copper foil to DuPont Kapton? polyimide film using a proprietary C-staged modified acrylic adhesive. What distinguishes it within the LF9150 series and across the broader LF lineup is its 127 ?m (5.0 mil) Kapton film ¡ª the thickest standard polyimide dielectric available in the LF single-sided range.
Breaking down the product code: “LF” identifies the acrylic adhesive system; “9150” encodes the construction (1 oz copper / 1 mil adhesive / 5 mil Kapton); and “R” designates rolled annealed copper. The full three-layer stack is:
- Rolled annealed (RA) copper foil?¡ª 35 ?m (1.0 oz/ft?)
- C-staged modified acrylic adhesive?¡ª 25 ?m (1.0 mil)
- Kapton? polyimide film?¡ª 127 ?m (5.0 mil)
The material is certified to IPC-4204/1, fully RoHS compliant, and manufactured under DuPont’s ISO 9001:2015 quality management system. It sits at the top of the standard LF single-sided product table in terms of dielectric thickness ¡ª one rung above LF9120R (2 mil Kapton) and three rungs above the ubiquitous LF9110R (1 mil Kapton).
DuPont Pyralux LF9150R: Full Construction and Performance Specs
Table 1 ¡ª LF9150R Physical Construction
| Parameter | Value |
| Product Code | LF9150R |
| Copper Type | Rolled Annealed (RA) |
| Copper Thickness | 35 ?m (1.0 oz/ft?) |
| Adhesive Type | C-staged Modified Acrylic |
| Adhesive Thickness | 25 ?m (1.0 mil) |
| Kapton? Film Thickness | 127 ?m (5.0 mil) |
| Total Nominal Thickness | ~187 ?m (7.35 mil) |
| Construction | Single-Sided Clad |
| IPC Certification | IPC-4204/1 |
| RoHS Compliant | Yes |
Table 2 ¡ª LF9150R Electrical and Mechanical Properties
| Property | Typical Value | Test Method |
| Dielectric Constant (Dk) @ 1 MHz | 3.6 | IPC-TM-650 2.5.5.3 |
| Dielectric Constant (Dk) @ 10 GHz | 3.0 | ASTM D2520 |
| Loss Tangent (Df) @ 1 MHz | 0.02 | IPC-TM-650 2.5.5.3 |
| Loss Tangent (Df) @ 10 GHz | 0.02 | ASTM D2520 |
| Peel Strength (after lamination) | 1.8 N/mm (10.0 lb/in) | IPC-TM-650 2.4.9 |
| Peel Strength (after solder) | 1.6 N/mm (9.0 lb/in) | IPC-TM-650 2.4.9 |
| Dimensional Stability (MD/TD) | ¡À 0.10% | IPC-TM-650 2.2.4 |
| Solder Float (288¡ãC, 10 s) | Pass | IPC-TM-650 2.4.13 |
| Volume Resistivity | > 10?? ¦¸¡¤cm | IPC-TM-650 2.5.17 |
| Surface Resistance | > 10?? ¦¸ | IPC-TM-650 2.5.17 |
Note that these values are shared across the Pyralux LF family ¡ª the dielectric properties reflect the Kapton/acrylic system, not just one construction. What changes significantly with the 5 mil Kapton is mechanical behavior, impedance geometry, and dimensional handling, all of which are covered below.
Table 3 ¡ª LF9150R Processing Conditions
| Parameter | Range |
| Part Temperature | 182 ¨C 199¡ãC (360 ¨C 390¡ãF) |
| Lamination Pressure | 14 ¨C 28 kg/cm? (200 ¨C 400 psi) |
| Time at Temperature | 1 ¨C 2 hours |
| Storage Temperature | 4 ¨C 29¡ãC (40 ¨C 85¡ãF) |
| Storage Humidity | < 70% RH |
| Shelf Life (warranty) | 2 years from Certificate of Analysis date |
Table 4 ¡ª Standard Packaging
| Parameter | Specification |
| Sheet Sizes Available | 24¡Á36 in / 24¡Á18 in / 12¡Á18 in |
| Minimum Sheets per Pack | 4 |
| Maximum Sheets per Pack | 25 |
The Significance of 5 mil Kapton: Why Dielectric Thickness Matters
Five mils of Kapton isn’t a random design choice ¡ª it solves specific engineering problems that thinner constructions cannot. Here’s what the thick dielectric actually buys you.
Controlled Impedance in Single-Sided Flex Designs
Controlled impedance is one of the primary drivers for specifying thick Kapton in a flex laminate. In a microstrip transmission line on a single-sided flex substrate, characteristic impedance is governed by the trace width, copper thickness, and the height of the dielectric separating the trace from the reference plane. With a Dk of 3.6 at 1 MHz (and 3.0 at 10 GHz) from the Kapton/acrylic stack, the relationship between dielectric height and target impedance is well-defined.
For a 50 ¦¸ microstrip target, thicker dielectric allows wider traces at the same impedance. Wider traces are easier to manufacture, have lower resistive loss, and provide more tolerance margin for the fabricator. The 5 mil Kapton in LF9150R gives designers significantly more room to work with compared to the 1 mil construction in LF9110R ¡ª which would require extremely narrow traces to hit 50 ¦¸ on a single layer.
Dimensional Stability for Fine-Pitch Processing
Thicker polyimide film is inherently more dimensionally stable during thermal processing than thin film of the same material. The Kapton film in LF9150R maintains ¡À0.10% dimensional stability (MD/TD) per IPC-TM-650 2.2.4 ¡ª the same specification as the rest of the LF family ¡ª but the thicker substrate is more resistant to distortion during lamination, etching, and coverlay pressing. For high-density designs with fine-pitch features and tight registration requirements, this mechanical stability reduces the risk of layer-to-layer misregistration in multilayer builds.
Mechanical Stiffness and Handling in Assembly
Single-sided flex circuits built on 1 mil Kapton (LF9110R) are extremely compliant ¡ª sometimes too compliant for automated assembly handling. A 5 mil Kapton substrate in LF9150R provides noticeably more bending stiffness in the unetched laminate state, which can simplify pick-and-place setup, component placement accuracy, and solder paste printing. This is a practical consideration that rarely shows up in datasheets but matters enormously on the assembly floor.
Thermal Management and Via Reliability
A thicker polyimide dielectric distributes thermal stress more effectively across the laminate thickness during soldering and thermal cycling. For through-hole vias or component mounting in a flex design, the greater dielectric thickness of LF9150R provides more material for the via barrel to grip, improving pull-through resistance. It also increases the separation between the copper trace and any opposing metallic structure, which affects both electrical isolation and thermal spreading.
DuPont Pyralux LF9150R vs LF9110R and LF9120R: Thickness Comparison
This is the table engineers actually need when selecting between Kapton thickness options.
Table 5 ¡ª LF9150R vs LF9120R vs LF9110R: Head-to-Head Comparison
| Attribute | LF9110R | LF9120R | LF9150R |
| Copper Type | Rolled Annealed (RA) | Rolled Annealed (RA) | Rolled Annealed (RA) |
| Copper Thickness | 35 ?m (1.0 oz) | 35 ?m (1.0 oz) | 35 ?m (1.0 oz) |
| Adhesive Thickness | 25 ?m (1.0 mil) | 25 ?m (1.0 mil) | 25 ?m (1.0 mil) |
| Kapton Thickness | 25 ?m (1.0 mil) | 51 ?m (2.0 mil) | 127 ?m (5.0 mil) |
| Total Approx. Thickness | ~85 ?m (3.35 mil) | ~111 ?m (4.35 mil) | ~187 ?m (7.35 mil) |
| Dielectric Constant (Dk) @ 1 MHz | 3.6 | 3.6 | 3.6 |
| Loss Tangent (Df) @ 1 MHz | 0.02 | 0.02 | 0.02 |
| Relative Bending Stiffness | Low | Moderate | High |
| Controlled Impedance Suitability | Limited | Moderate | Strong |
| Dimensional Stability (processing) | Good | Very Good | Excellent |
| Best Fit | Standard flex interconnect | Balanced flex/stiffness | Thick dielectric / impedance control |
| IPC-4204/1 Certified | Yes | Yes | Yes |
The critical engineering insight from this table is that all three share identical copper weight, adhesive construction, and electrical material properties. The Kapton thickness is the single design variable, and choosing between them is a stackup geometry and mechanical performance decision ¡ª not a material quality decision.
Where LF9150R Fits in the Full Pyralux LF Single-Sided Product Matrix
Table 6 ¡ª Pyralux LF Single-Sided Standard Offerings
| Product Code (RA) | ED Equivalent | Copper (oz/ft?) | Adhesive (mil) | Kapton (mil) | Total (approx. mil) |
| LF7012R | LF7012E | 0.5 | 0.5 | 0.5 | 1.9 |
| LF7062R | LF7062E | 0.5 | 0.5 | 1.0 | 2.4 |
| LF7004R | LF7004E | 0.5 | 1.0 | 0.5 | 1.9 |
| LF7002R | LF7002E | 1.0 | 0.5 | 0.5 | 1.9 |
| LF9110R | LF9110E | 1.0 | 1.0 | 1.0 | 3.4 |
| LF9120R | LF9120E | 1.0 | 1.0 | 2.0 | 4.4 |
| LF9150R | LF9150E | 1.0 | 1.0 | 5.0 | 7.4 |
| LF9210R | LF9210E | 2.0 | 1.0 | 1.0 | 3.8 |
| LF9220R | LF9220E | 2.0 | 1.0 | 2.0 | 4.8 |
The LF9150R is the thickest-dielectric option in the standard LF single-sided range. No standard product code sits above it in Kapton thickness within the LF family. If a project requires more dielectric thickness than 5 mil with an acrylic adhesive system, that typically means moving to a custom construction or considering the adhesive-free Pyralux AP family, which is available in polyimide thicknesses from 1 to 6 mil (and up to 20 mil by special order).
When Should You Actually Specify DuPont Pyralux LF9150R?
The right applications for LF9150R are specific. This isn’t a general-purpose flex laminate ¡ª it’s a tool for a defined set of design requirements.
Specify LF9150R when you need controlled impedance on a single-sided flex layer. The thick Kapton gives you the dielectric height necessary to hit 50 ¦¸ or 75 ¦¸ microstrip targets with trace widths that are actually manufacturable. On 1 mil Kapton, hitting 50 ¦¸ on a single-layer microstrip with 1 oz copper gets you into sub-4 mil trace widths depending on Dk assumptions ¡ª that’s tight tolerancing for flex fabrication. On 5 mil Kapton, you’re in the 12¨C15 mil range for the same impedance target, which is much more process-friendly.
Specify LF9150R when the flex circuit also functions as a structural element. Some designs route flex circuits through a device in a way that the flex substrate itself must provide a minimum bend radius enforcement ¡ª acting as a strain-relief spacer as much as a circuit element. The 5 mil Kapton resists tight bending, which in some architectures is exactly the right behavior.
Specify LF9150R for flex circuits in high-vibration environments where thinner substrates would experience fatigue from resonant flex motion. The stiffer substrate self-damps small amplitude vibrations better than a 1 mil construction.
Do not specify LF9150R for dynamic flex zones. Despite having RA copper (which supports repeated bending better than ED copper), the thick Kapton increases the neutral axis offset and raises bending stress in the copper layer during deflection. For true dynamic flex applications with hundreds of thousands of flex cycles, a thinner construction ¡ª LF9110R or, better, an adhesive-free Pyralux AP in 1¨C2 mil Kapton ¡ª is the correct choice.
Do not specify LF9150R where total assembly thickness is constrained. At 7.35 mil total thickness, this laminate contributes significantly to a flex stackup. In ultra-thin device designs where every micron counts, thinner options are more appropriate.
Quality, Traceability, and Regulatory Compliance
Every lot of DuPont Pyralux LF9150R ships with a Certificate of Conformance (COC) and is manufactured under DuPont’s ISO 9001:2015 certified QMS. Complete material and manufacturing lot records, including retained samples, are maintained for traceability. Roll labels include lot number, DuPont order number, IPC specification, and customer part number ¡ª save these labels.
LF9150R is IPC-4204/1 certified and RoHS compliant. For regulated industries (defense, aerospace, non-implantable medical devices), this traceability chain is often a contractual requirement, and Pyralux LF fulfills it. As with all Pyralux LF materials, DuPont cautions against use in permanent implantable medical applications ¡ª consult DuPont Medical Caution Statement H-50102-5 for any medical end-use.
Useful Resources for Engineers Working with LF9150R
These resources are directly relevant for qualifying, designing, or procuring DuPont Pyralux LF9150R:
- DuPont Pyralux Official Product Page?¡ª ?¡ª official source for current datasheets, the Laminate Product Selector tool, and processing guides
- DuPont Pyralux LF Datasheet (EI-10117)?¡ª The authoritative spec document for the LF family including LF9150R; download from pyralux.dupont.com
- DuPont Pyralux LF Processing Guide?¡ª Available through your DuPont or authorized distributor representative; essential for lamination press setup
- Pyralux Safe Handling Guide?¡ª Available at pyralux.dupont.com; required reading before production handling
- IPC-4204/1?¡ª “Flexible Metal-Clad Dielectrics for Use in Fabrication of Flexible Printed Boards” ¡ª the governing specification LF9150R is certified against
- IPC-TM-650?¡ª The standard test method suite referenced for all Pyralux property values (peel strength, dimensional stability, electrical, etc.)
- IPC-2223?¡ª “Sectional Design Standard for Flexible Printed Boards” ¡ª the design standard engineers should be working from when designing with any flex laminate
- IPC-4562?¡ª “Metal Foil for Printed Wiring Applications” ¡ª relevant if you need to understand the RA copper foil grade specifications for LF9150R
- DuPont Medical Caution Statement H-50102-5?¡ª Required review for any medical end-use application
5 FAQs About DuPont Pyralux LF9150R
FAQ 1: Can LF9150R be used in a dynamic flex zone?
Technically yes, but it’s not the right tool. The rolled annealed copper in LF9150R does provide flex fatigue capability, but the thick 5 mil Kapton increases the strain experienced by the copper during bending. As Kapton thickness increases, the outer surfaces of the laminate experience higher tensile and compressive stress for a given bend radius. For static flex and limited-cycle flex (a few thousand cycles or less), LF9150R is fine. For continuous dynamic flex with high cycle counts ¡ª think >100,000 cycles ¡ª you’ll want a thinner construction like LF9110R, or an adhesive-free Pyralux AP in a thin dielectric, which handles flex fatigue considerably better.
FAQ 2: Is LF9150R compatible with standard flex PCB processes?
Yes, fully. Pyralux LF materials process using standard flexible circuit fabrication methods: photolithographic etching, screen printing, SMT assembly, through-hole processing, and coverlay lamination. The C-staged acrylic adhesive in LF9150R passes solder float testing at 288¡ãC for 10 seconds, confirming compatibility with both reflow and wave solder. The thick Kapton substrate actually simplifies some processing steps ¡ª the stiffer material handles better in automated equipment compared to ultra-thin flex substrates.
FAQ 3: What’s the difference between LF9150R and LF9150E?
The “R” suffix designates rolled annealed (RA) copper; the “E” suffix would designate electro-deposited (ED) copper. The construction otherwise is identical ¡ª same 1 mil adhesive, same 5 mil Kapton, same electrical properties. RA copper (LF9150R) offers better flex fatigue life due to its elongated horizontal grain structure, while ED copper would be slightly more cost-effective but more prone to fatigue cracking under repeated bending. For a thick-Kapton construction like LF9150R that’s already less suited to dynamic flex, the RA copper’s fatigue advantage still matters at the margins.
FAQ 4: How does LF9150R compare to Pyralux AP9151R for a controlled impedance application?
Both offer 5 mil dielectric and 1 oz RA copper, but the dielectric system is completely different. LF9150R uses a three-layer construction (copper / acrylic adhesive / Kapton) while Pyralux AP9151R is an all-polyimide, adhesive-free construction (copper bonded directly to polyimide with no acrylic layer). The AP series has a Dk/Df optimized for higher-frequency performance and provides better dimensional stability because the acrylic adhesive layer (which has its own flow behavior during lamination) is eliminated. For most controlled impedance applications below 5 GHz, LF9150R is adequate. Above that frequency, or where tighter Dk tolerance is required, Pyralux AP is the better specification.
FAQ 5: What are the storage and handling requirements for LF9150R, and when does it expire?
Store LF9150R in its original packaging at 4¨C29¡ãC (40¨C85¡ãF) and below 70% relative humidity. Keep it dry, clean, and protected from physical damage ¡ª thin copper edges can be sharp and the acrylic adhesive can pick up contamination if exposed. DuPont warrants the material for two years from the Certificate of Analysis date when storage conditions are maintained. Beyond that window, the acrylic adhesive may advance in cure state, which could reduce peel strength and lamination consistency. Always log the COC date when receiving material, and pull from oldest inventory first.
Final Thoughts on DuPont Pyralux LF9150R
DuPont Pyralux LF9150R is a niche-but-essential tool in the flex laminate toolkit. Its thick 5 mil Kapton dielectric makes it the right call for controlled impedance single-sided flex designs, structurally stiffer flex circuit architectures, and applications where the substrate needs to do more mechanical work than a thin flex can provide. The rolled annealed copper keeps flex fatigue capability in the picture, and the IPC-4204/1 certification and ISO 9001:2015 manufacturing quality make it a defensible choice for regulated, high-reliability programs.
The mistake to avoid is reaching for LF9150R on any design that has a genuine dynamic flex zone. In that case, thinner is better ¡ª the increased dielectric height works against flex endurance, not for it. Know your use case, check your bend radius math, and this material will serve you well.
All specifications cited are drawn from DuPont’s official Pyralux LF Copper-Clad Laminate data sheet (EI-10117). Verify against the current revision before design commitment. Performance data may vary based on construction and downstream processing.
Suggested Meta Description
Option 1 (160 characters, Yoast-optimized):
DuPont Pyralux LF9150R is the 1 oz RA copper / 5 mil Kapton flex laminate in the LF series. Full specs, Dk/Df values, comparison vs LF9110R & LF9120R, and when to use it.
Option 2 (slightly longer, rich snippet friendly):
Full engineering guide to DuPont Pyralux LF9150R: construction specs, controlled impedance design advantages, comparison vs LF9110R and LF9120R, application guidance, and 5 FAQs from a PCB engineer’s perspective.
