DuPont Pyralux flex laminates · Taiflex
DuPont Pyralux PCB: AP, LF & FR Flex Laminates
Flex and rigid-flex circuits built on DuPont Pyralux: all-polyimide adhesiveless Pyralux AP for dynamic flex and thin builds, acrylic-adhesive Pyralux LF and FR for cost-sensitive static flex, plus Taiflex polyimide FCCL as a qualified alternative.
- Pyralux AP
- Adhesiveless
- Pyralux LF / FR
- Acrylic adhesive
- Dk @ 10 GHz (LF/FR)
- 3.0
- Solder float pass
- 288 °C
What is Pyralux
What is DuPont Pyralux?
DuPont Pyralux is a family of flexible copper-clad laminates, coverlays and bondplies built on Kapton polyimide film. Pyralux AP bonds copper directly to polyimide with no adhesive layer, while Pyralux LF and FR bond copper to Kapton with an acrylic adhesive. Together they are the most widely specified materials for flex and rigid-flex PCBs.
The choice between them decides how far a flex circuit can bend, how thin it can be, how many lamination cycles it survives and what it costs. We build on the grade named on your drawing, or recommend one from the bend, temperature and impedance requirements of the design.
AP vs LF vs FR
Pyralux AP vs LF vs FR.
| Family | Construction | Strengths | Typical use |
|---|---|---|---|
| Pyralux AP | All-polyimide, adhesiveless double-sided clad | Thinnest builds, best dynamic flex life, higher temperature, stable dielectric | Dynamic flex, rigid-flex, fine-line and impedance-controlled flex |
| Pyralux LF | Kapton + C-staged modified acrylic adhesive | Proven, cost-effective, multiple lamination cycles | Static flex, flex-to-install, multilayer flex |
| Pyralux FR | Kapton + flame-retardant modified acrylic adhesive | UL 94 VTM-0, multiple lamination cycles | Flex that needs a flame rating, rigid-flex outer flex layers |
| Pyralux coverlay / bondply | Kapton + adhesive | Protects and bonds flex layers | Coverlay over traces; bonding flex layers in rigid-flex |
Properties
Pyralux LF and FR typical properties.
| Property | Pyralux LF (LF9110R) | Pyralux FR (FR9110R) |
|---|---|---|
| Dk @ 1 MHz | 3.6 | 3.6 |
| Dk @ 10 GHz | 3.0 | 3.0 |
| Df @ 1 MHz | 0.02 | 0.03 |
| Df @ 10 GHz | 0.02 | 0.02 |
| Peel strength after lamination | 1.8 N/mm (10.0 lb/in) | 2.1 N/mm (12.0 lb/in) |
| Peel strength after solder | 1.6 N/mm (9.0 lb/in) | 1.9 N/mm (11.0 lb/in) |
| Dimensional stability (MD/TD) | ± 0.10% | ± 0.10% |
| Solder float, 288 °C, 10 s | Pass | Pass |
Pyralux AP removes the adhesive layer, so its dielectric is polyimide only. That gives a thinner, more stable dielectric and better high-temperature behaviour than adhesive-based clads. We use the AP data sheet value for the specific product code (copper weight and dielectric thickness) in impedance models rather than a generic number.
Taiflex
Taiflex polyimide FCCL as an alternative.
Taiflex supplies adhesiveless (2-layer) and adhesive-based (3-layer) polyimide flexible copper-clad laminates and coverlay. They are widely used in consumer, automotive and industrial flex. When your drawing allows an equivalent, a Taiflex FCCL can shorten lead time or reduce cost compared with a specified Pyralux grade. We propose a substitution only in writing at quote, with the matching data sheet, and only use it after your approval.
| Need | DuPont option | Taiflex option |
|---|---|---|
| Dynamic flex, thin build | Pyralux AP (adhesiveless) | 2-layer adhesiveless FCCL |
| Static flex, cost first | Pyralux LF | 3-layer adhesive FCCL |
| Coverlay | Pyralux / Kapton coverlay | Taiflex coverlay |
How to choose
Choosing a Pyralux grade.
Start from how the flex will move. A flex that bends thousands or millions of times in a hinge, print head or sliding mechanism should use adhesiveless Pyralux AP with rolled-annealed copper, because the adhesive layer in LF and FR is the usual crack-initiation point under repeated bending. A flex that is bent once to install and then stays put can use LF or FR at lower cost.
Then check temperature and flame rating. Assemblies that see several lead-free reflows or high operating temperatures favour AP. Products that need a UL flame rating on the flex itself point to FR. Finally, check thickness and impedance: AP gives the thinnest controlled dielectric, which matters for 50 Ω and 90–100 Ω lines on thin flex.
Design rules
Flex design rules on Pyralux.
- Use rolled-annealed (RA) copper and run traces perpendicular to the bend line in dynamic areas
- Keep plated holes, vias and stiffener edges out of the bend area
- Stagger traces on double-sided flex so copper on both sides does not stack in the bend
- Use hatched ground planes on flex layers to keep them flexible
- Start from IPC-2223 bend-radius guidance and confirm with the actual stack-up
- Specify the Pyralux product code (copper weight and dielectric thickness) on the fabrication drawing
Rigid-flex
Pyralux in rigid-flex constructions.
In rigid-flex boards the flex core is usually Pyralux AP, laminated to FR-4 or polyimide rigid sections with no-flow prepreg and bondply. The rigid-to-flex transition is where most failures start, so we control adhesive squeeze-out, coverlay openings and the distance from the transition to the first plated hole. For air-gap constructions, unbonded flex layers move independently for a tighter bend. See rigid-flex PCB for constructions and capabilities.
RFQ
What to include in a Pyralux RFQ.
- Laminate name and grade exactly as on your drawing, or “or equivalent” if substitution is allowed
- Pyralux family and product code (e.g. AP, LF, FR) and copper type (RA or ED)
- Static or dynamic flex, bend radius and cycle count
- Coverlay, stiffeners and finish
- Layer count, finished thickness and tolerance
- Impedance targets and reference layers
- IPC class, quantity and schedule
FAQ
Material questions.
What is the difference between Pyralux AP and Pyralux LF?
Pyralux AP is all-polyimide and adhesiveless; Pyralux LF bonds copper to Kapton with an acrylic adhesive. AP is thinner and better for dynamic flex and high temperature; LF costs less for static flex.
Is Pyralux the same as Kapton?
No. Kapton is DuPont’s polyimide film. Pyralux is the family of copper-clad laminates, coverlays and bondplies made with Kapton or other polyimide.
What is the dielectric constant of Pyralux LF?
3.6 at 1 MHz and 3.0 at 10 GHz for LF9110R, per the DuPont data sheet.
Which Pyralux grade is best for dynamic flex?
Adhesiveless Pyralux AP with rolled-annealed copper.
Can you use Taiflex instead of Pyralux?
Yes, when your drawing allows an equivalent. We propose the Taiflex grade in writing at quote and only use it with your approval.
Do you build rigid-flex on Pyralux AP?
Yes. Pyralux AP is our standard flex core for rigid-flex PCBs.
Ready when your files are
Send your stack-up for a material check.
Upload Gerber, ODB++ or IPC-2581 data. Every quote includes a written engineering DFM review, typically within one business day.