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Product image 1: Flex & Rigid Flex


Get flex and rigid-flex PCBs manufactured in the United States at any volume. Sierra Circuits leads the industry in quality and turnaround times.

  • Freedom of design
    The elastic nature of flexible PCBs allows for placement around edges and folds.
  • Reduced space and weight
    Flex circuit’s polyimide material is lighter than FR4. The use of flexible flat cables (FCC) take up less space than traditional wires.
  • Increased reliability and durability
    Flex circuits can be significantly warped/deformed without breakage. Standard materials can withstand as many as 200,000 bending cycles.
  • Improved heat dissipation and airflow
    Polyimide flex materials are suited for very high temperatures compared to FR4.
  • Use in harsh environment
    Flex circuits can be built with materials that are suitable to use in harsh operating environments (materials that have the following properties: waterproof, moisture proof, shock proof, high temperature oil, corrosion resistant).

Ready to start building with flexible PCBs? Sierra Circuits engineers can help you efficiently design and manufacture your flex, rigid-flex, and HDI flex PCBs, right here in the U.S.

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Learn about our services, capabilities, and testing for quick turn flex PCBs and rigid-flex PCBs. Sierra Circuits manufactures your flexible circuits with full intellectual property protection.

Surface finishes:

  • HASL (vertical or horizontal)
  • Lead-free HASL
  • OSP (Shikoku F2)
  • OSP (Entek)
  • ENIG
  • Immersion silver
  • Immersion white tin
  • Tin nickel
  • Electrolytic soft gold
  • Electrolytic hard gold
  • Selective gold

Standard flex materials:

  • Polyimide (Kapton) 0.5 mil to 5 mils (.012mm – .127mm)
  • Adhesiveless copper clad base material 1 mil to 5 mils
  • Flame retardant laminate, base material, and Coverlay
  • High performance epoxy laminate and prepreg
  • High performance polyimide laminate and prepreg
  • UL and RoHS compliant material on request
  • High Tg FR4 (170+ Tg), polyimide (260+ Tg)

PCB attributes

Flex Rigid-flex
Min Layer Count 1 1
Max Layer Count 12 ≤ 16
Min Core thickness .001″ (.025 mm) .002″ (.051 mm)
Max Finished Copper Weight (I/L) 2 oz (59 ml) 3 oz (89 ml)
Max Finished Copper thickness (O/L) 12 micron (.012 mm) 9 micron (.009 mm) (only for O/L)
Max Panel Size 12×18 12×18
Smallest Mechanical Drill Diameter .0079″ (.201 mm) .0071″ (.180 mm)
Smallest Laser Drill Diameter No .005″ (.127 mm)
Min Finished Hole Size .006″ (.152 mm) .006″ (.152 mm)
Max through Hole Aspect Ratio 10:1 10:1
Max Blind Via Aspect Ratio .75:1 .75:1
Min Trace and Space ≥ .0035”(.089 mm) ≥ .0035”(.089 mm)(rigid)
Min Pad Size for Test .016″ (.406 mm) .005” (.127 mm) (rigid)
Process Pad Diameter D + .014″ (.356 mm) (1-mil (.025 mm) annular ring) D + .014″ (.356 mm) (1-mil (.025 mm) annular ring)
Stacked Vias No No
Min Wire Bond Pad Size > .006″ (.152 mm) > .006″ (.152 mm)
Controlled Impedance Tolerance 10% 5%
Solder Mask Registration Within .002″ (.051 mm) Within .002″ (.051 mm)
Solder Mask Feature Tolerance .001″ (.025 mm) .001″ (.025 mm)
Solder Mask Min Dam Size .004″ (.102 mm) .001″ (.025 mm)
Min Diameter Route Cutter Available .019″ (.483 mm) .024″ (.610 mm)
Mechanical Routed Part Size Tolerance .003″ (.076 mm) .010″ (.254 mm)
Bow and Twist Tolerance N/A As per spec
Thickness Tolerance +/- .002″ (.051 mm) 10%
Sequential Laminations N/A 2
Buried Vias Yes Yes
Blind Vias Yes Yes
Conductive Filled Vias No Yes
Non Conductive Filled Vias No Yes

Surface finishes

Flex Rigid-flex
HASL (Vertical or Horizontal) Yes (not recommended) Yes
Lead Free HASL Yes (not recommended) Yes
OSP (Shikoku F2) Yes (not recommended) Yes
OSP (Entek) Yes (not recommended) Yes
ENIG (Electroless Nickel/Immersion Gold) Yes (most common) Yes
Immersion Silver Yes (not recommended) Yes
Immersion White Tin No No
Tin Nickel No No
Electrolytic Soft Gold Yes Yes
Electrolytic Hard Gold Yes Yes
Selective Gold Yes Yes

Solder mask colors

Rigid-flex Rigid-flex
Amber Yes Yes
Green Yes Yes
Black No Yes
Red No Yes
Blue No Yes
Yellow No Yes
White No Yes
Clear No Yes
Bright White No Yes
Purple No Yes


Flex Rigid-flex
White Yes Yes


Flex Rigid-flex
Routed Array Yes Yes
V Score, Edge to Copper .002″ (.051 mm) .01″ (.254 mm)
V Score Angles No Yes
Countersink Yes Yes
Counterbore Yes Yes
Bevel Yes Yes
Milling Yes Yes
Edge Castellation Yes Yes
Edge Plating Yes Yes
Heatsinks No No

Electrical test

Flex Rigid-flex
10 Volt Yes Yes
40 Volt (Burn-In Boards) Yes Yes
250 Volt Yes Yes
500 Volt Yes Yes

Laminate materials

Flex Rigid-flex
Flexible Poyimide Yes Yes
Arlon 85NT No No
Bergquist No No
Hybrid Constructions Yes Yes
Isola FR406 Yes Yes
Isola FR408 HR Yes Yes
Isola P95 Yes Yes
Isola P96 Yes Yes
Iteq IT180 Yes Yes
Panasonic R1766 Yes Yes
Panasonic R1755 Yes Yes
Panasonic Megtron Yes Yes
Nelco N4000-13 Yes Yes
Nelco N4000-29 Yes Yes
Nelco BT N5000 Yes Yes
Nelco N7000-2 Yes Yes
No Flow Prepreg Yes Yes
Isola 370HR Yes Yes
Polyclad Getek No No
PSA Bond Film Yes Yes
Rogers 3000 Series No No
Rogers R4000 Series No No
Rogers 5000 Series No No
Rogers 6000 Series No No
Rogers TMM No No

Available reports

Flex Rigid-flex
Microsection Yes Yes
Solderability Yes Yes
X-Ray Fluorescence Yes Yes
Ionic Contamination Yes Yes
Time Domain Reflectometry Test (TDR) Yes Yes
FAI Yes Yes
Certificate of Compliance Yes Yes


Flex Rigid-flex
94VO Yes Yes

PCB classifications mil-spec

Flex Rigid-flex
MIL-PRF-55110 No No
MIL-PRF-31032/1 No No
MIL-PRF-31032/2 No No
IPC 6012, Class 1, 2 and 3 Yes Yes
ISO 9001:2015 Yes Yes
ISO 13485:2016 Yes Yes
Trusted by innovators

Engineers at the world’s most innovative companies choose Sierra Circuits for the highest quality flex & rigid-flex PCB manufacturing and assembly, right here in the USA.

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Product Image 2: Flex & Rigid Flex


Whether you need a high-volume HDI flex PCB run or a low-volume quick turn flex PCB run, there’s a reason Sierra Circuits leads the industry in quality and performance. Our engineers and technicians manufacture and assemble the most reliable flex, rigid-flex, and HDI flex PCBs in the United States.

Ideal for:

  • PCB designers and electrical engineers building prototypes or bringing products to market
  • Contract manufacturers who need fast, predictable lead times
  • Purchasing teams who require pricing and supply-chain transparency
  • Tinkerers, hobbyists, and builders who want to develop IoT home automation devices

To learn more about flex design guidelines, download our Flex PCB Design Guide.

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Sierra Circuits is
headquartered in Silicon Valley.
We welcome visitors at
our 70,000 sqft facility,
located at 1108 West Evelyn Avenue
in Sunnyvale, California.
Book a tour with an account manager today!
Let us introduce you to one of the most innovative communities of engineers and designers in the world.
We can help you plan your project from design to assembled board.


Our 70,000 sqft state-of-the-art campus in the heart of Silicon Valley contains the most advanced equipment required for the manufacture and assembly of your PCBs. Whether you’re looking for standard quick turn PCBs or boards with the tightest tolerances, made from exotic metals, there’s a reason Sierra Circuits leads the industry in quality and performance.

PCBs manufactured and assembled in the United States



We can turn your flex and rigid-flex circuits in as fast as in 24 hours.

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24 hours a day, 7 days a week.

Call us: +1 (800) 763-7503
Email us: through our Customer Care form

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