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What are Rigid and Flex Polyimide PCBs and Laminate Materials

PCBONLINE Team

Mon, Sept 26, 2022

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Polyimide is the most common substrate material for flexible PCBs. Do you know there are also polyimide rigid PCBs? This article unveils polyimide rigid PCBs and polyimide flex PCBs respectively, and also the laminate you can choose for polyimide rigid and flex PCBs.

Part 1: Features of the Polyimide PCB Material

Polyimide PCBs use PI as the substrate material and can be flex, rigid, and rigid-flex. Polyimide, a type of high-performance plastic, abbreviated PI, is a polymer consisting of imide monomers.

polyimide rigid-flex PCB

Polyimide circuit boards can be used for OLED screen boards, touch sensor panels, motors, transformers, wind turbines, high-speed trams, smartphones, thermal-management control systems, and power supplies.

Why can PI PCBs find so many high-end applications? You can check the features of polyimide materials below.

  • Good electrical insulation. PI has a volume resistance of 1017Ω·cm, and it can be used for high-level insulation systems.
  • Strong mechanical properties. The tensile strength of homophenyl PI film reaches 250MPa, and that of biphenyl PI film reaches 530MPa.
  • Small dielectric constant and dielectric loss. PI has a dielectric constant of 3.4 and a dielectric loss of 0.004 to 0.007. For this reason, PI PCBs can be used in high-frequency and high-speed fields.
  • Low thermal expansion. PI has a thermal expansion coefficient of only (2~3)×10^(-5)/℃.

From the polyimide PCB manufacturer PCBONLINE, you can choose the PI laminates such as Ventec VT-901, Arlon 85N, and Nelco N7000-2 HT for polyimide rigid PCBs. You can check the specifications of available PI rigid PCB laminates from PCBONLINE by clicking the laminate name on our laminate page.

Part 2: Polyimide Rigid PCB and Laminate Materials

polyimide rigid PCB

Polyimide rigid PCBs are special PI PCBs that use toughened polyimide material for use in high-reliability applications. The Tg for rigid polyimide PCBs is 250℃ and above, and they can withstand lead-free soldering temperatures.

A rigid polyimide PCB consists of the PI substrate, prepreg (PP), and copper layers. The properties of the PP are also polyimide. So in fact, you can consider a rigid polyimide PCB as an FR4 PCB, and the difference is that it uses halogen-free toughened PI without epoxy added.

Polyimide rigid PCBs meet RoHS and WEEE requirements, and you can use them for engine/flight controls, power supplies, industrial sensors, burn-in boards, automotive controls, etc.

You can check PCBONLINE's rigid polyimide PCB laminates and fabrication specifications below.

PCBONLINE's Rigid Polyimide PCBs
Rigid polyimide PCB laminates models

Ventec VT-901, VT-90H

Arlon 85N, 85NT, 35N, 33N

Nelco N7000-2 HT, N7000-2 VO

Copper thickness
1/3oz to 6oz
HDI stackup
1+N+1,2+N+2,3+N+3 (with copper filling)
Impedance control
±10%
PI rigid PCB thickness
0.15mm to 3.2mm
Minimum line width/space
2.5mil/2.5iml
Minimum drill bit size
8mil
Through-hole size tolerance

PTH: ±3mil

NPTH:±2mil

Profile tolerance

Punching: ±3mil

Routing: ±4mil

Solder mask tolerance

Line to pad: ±4mil

Registration: ±2mil

Surface finish
Lead-free HASL, ENIG, OSP, immersion tin, immersion silver, peelable solder mask, carbon ink

Part 3: Polyimide Flex PCB and Laminate Materials

polyimide flex PCBs

Polyimide flexible PCBs, the most common FPC, consist of the coverlay and flex copper-clad laminates (FCCL). Polyimide takes up the most in PI PCB material properties. The FPC coverlay consists of a PI film and an adhesive layer, and the FCCL consists of PI, copper, and adhesive. The color of the external PI film of flexible polyimide PCBs can be yellow, white, or black.

Rigid-flex polyimide PCBs belong to flexible polyimide PCBs. The inner layers are an FPC, and while the external rigid layers are FR4 PCB layers.

Regarding flexible polyimide laminate materials, DuPont is the most famous provider. However, most of our clients want TaiFlex polyimide flex PCBs because the PI laminates are more cost-effective.

You can check PCBONLINE's polyimide flex PCB laminates and fabrication specifications below.

PCBONLINE's Polyimide FPC and rigid-flex PCB capabilities
Flex PI copper clad laminates

TaiFlex adhesive FCCL, adhesiveless DFCCL, low-loss FCCL, halogen-free coverlay, high-Tg coverlay, anti-migration coverlay, low-loss coverlay, high-Tg bonding sheet, anti-migration bonding sheet, low-loss bonding sheet, stiffener, and composite film

DuPont Kapton B, Kapton CRC, Kapton EN, Kapton EN-A, En-C, EN-Y, EN-Z, Kapton FCRC, Kapton FN, Kapton FPC, Kapton FWN, Kapton FWR, Kapton GS Heat Spreading Film, Kapton HN, Kapton HPP-ST, Kapton MT and Kapton FMT thermally conductive films, Kapton MT higher thermally conductive film, Kapton PRN, Kapton PST

Shengyi SF490, SF280, SF335C, SF215C, DL, SL, SF201, SF202, SF230, SF305, SF701, SF202C, SF206C, SF305C, SF315C, SF325C, SF206B, SF315B, SF325B, SF168N, S1141, S1125, S1150G, BIF201, BIF202

Copper thickness
12μm, 18μm, 35μm, 70μm, 105μm
PI thickness
12.5μm, 25μm, 50μm, 75μm
Adhesive thickness
20μm
Minimum PI FPC thickness
2.36mm
Surface finish
ENIG, OSP, immersion, immersion silver, hard gold plating
PCB layer

Flexible PCB: 1 to 10 layer

Rigid-flex PCB: 2 to 30 layer

Minimum line width/space
1.6mil/1.6mil
PCB stiffeners
PI, FR4, stainless steel

Part 4: One-Stop Polyimide Rigid and Flex PCB Manufacturer

PCBONLINE is a one-stop polyimide circuit board manufacturer, providing rigid, flexible, and rigid-flex polyimide PCBs/PCBA. Founded in 1999, our two large advanced PCB manufacturing bases and one PCB assembly factory are ISO, IATF, IPC, UL, REACH, and RoHS certified.

polyimide PCB manufacturer PCBONLINE

You have checked our polyimide circuit board manufacturing capabilities above. What are the advantages of working with us for polyimide PCBs?

    • PCBONLINE provides polyimide circuit board design, PCB fabrication, PCB assembly, and box-build assembly without a quantity limit.
    • From PCBONLINE, you can order polyimide PCBs using any laminate models above in the tables.
    • We will review your Gerber and provide free design for manufacturing (DFM) before PCB fabrication.
    • We offer one-on-one engineering support throughout your polyimide PCB/PCBA project.
    • Transparent pricing, free sample for bulk production, and we can help you pass quality certifications.

It takes us 1 day to 2 weeks to complete polyimide PCB fabrication and assembly. If you need box build assembly from us, we can design the enclosure and instruction manuals besides end-product assembly. You can send an email to info@pcbonline.com to get a quote.

Conclusion

There are rigid polyimide PCBs, flexible polyimide PCBs, and rigid-flex polyimide PCBs. The manufacturer PCBONLINE can fabricate and assemble all of them. If you need polyimide circuit board fabrication and related services, please don't hesitate to contact PCBONLINE.


© This article is an original work of the PCBONLINE team. Please indicate the author PCBONLINE if you reprint. If the article is reproduced without permission or indicating the author's source, PCBONLINE reserves the right to investigate the infringement.

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