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Flexible and Rigid-flex PCB Manufacturing
Sierra Circuits fabricates and assembles high-quality flex, rigid-flex,
and HDI-flex circuit boards right here in the United States.
Why and Where Do You Need Flex PCBs?
- Adapts to unique form factors and unconventional layouts with the ability to bend,
twist, and fold. - Supports compact designs while minimizing overall weight.
- Withstands high temperatures, humidity, and continuous motion.
- More resistant to vibrations, shocks, and mechanical stress.
Ideal for:
- Wearable technology – smartwatches, fitness trackers, medical wearables.
- Medical devices – pacemakers, hearing aids, imaging systems.
- Industrial and IoT applications – robotics, automation systems, and IoT sensors.
- Automotive electronics – airbag systems, dashboard displays, sensor modules.
Why Choose Sierra Circuits for your Flex PCB Fabrication?
- We don’t just manufacture Flex PCBs, we engineer precision, durability, and
performance into every board. Whether you need multilayer flex, rigid-flex, HDI, or
microvias, we deliver cutting-edge solutions tailored to your unique application. - With advanced fabrication methods like self-learning stack-up scaling, automated
imaging, laser and vision drilling, and precision routing, we ensure superior
quality. - Our DFM support and CAD-based design optimization ensure smooth production while enhancing signal integrity and electrical performance.
- We have extensive experience in building static and dynamic flexible designs enduring up to 200,000 bend cycles. We have standard procedures for handling polyimide, polyester (PET), and liquid crystal polymer (LCP) materials.
- We provide options like rolled annealed copper for dynamic flexing, electro-deposited copper for static applications, adhesive (acrylic and epoxy),
and adhesiveless constructions.
Our expertise
- Multilayer HDI flex and rigid-flex manufacturing
- DFM and CAD-based optimization
- Component stocking and on-site material inventory
- Dynamic designs enduring up to 200,000 bend cycles
- Adhesive and adhesiveless constructions
| Stack-Up | Stack-Up | |||
|---|---|---|---|---|
| Minimum Layer Count | 1 |   | ||
| Maximum Layer Count | 12 | |||
| Minimum Core Thickness | 1 mil (0.001 in/0.025 mm) | |||
| Maximum Finished Copper Thickness (inner layer) | 2 oz | |||
| Maximum Finished Copper Thickness (outer layer) | 2 oz | |||
| Thickness Tolerance (based on board thickness) | ±10% | |||
| Hybrid Constructions | Yes | |||
| No Flow Prepreg | Yes | |||
| Bow and Twist Tolerance | N/A | |||
| Sequential Lamination | N/A | |||
| Drill and Pad | Drill and Pad | |||
|---|---|---|---|---|
| Smallest Mechanical Drill Diameter | 7.1 mil (0.0071 in/0.180 mm) |   | ||
| Smallest Laser Drill Diameter | 6 mil (0.0060 in/0.152 mm) | |||
| Minimum Annular Ring (only 2 sided) |
| |||
| Blind Vias | Yes | |||
| Buried Vias | Yes | |||
| Stacked Vias | No | |||
| Conductive Filled Vias | No | |||
| Non-Conductive Filled Vias | No | |||
| Maximum Through Hole Aspect Ratio (Depending on the board thickness and finished hole) | 10:1 | |||
| Maximum Laser Via Aspect Ratio | 0.75:1 | |||
| Minimum Pad Size for Test | 16 mil (0.0160 in/0.406 mm) | |||
| Process Pad Diameter | D + 0.014" (0.356 mm) (1-mil (0.025 mm) annular ring) | |||
| Minimum Wire Bond Pad Size | >6 mil (0.0060 in/0.152 mm) | |||
| Trace and Spacing Clearances | Trace and Spacing Clearances | |||
|---|---|---|---|---|
| Minimum Trace Width | >=3.5 mil (0.0035 in/0.089 mm) |  | ||
| Minimum Trace Spacing | >=3.5 mil (0.0035 in/0.089 mm) | |||
| Controlled Impedance Tolerance | ±10% for Standard and ±5% for Advanced | |||
| Solder Mask and Surface Finish | Solder Mask and Surface Finish | |||
|---|---|---|---|---|
| Solder Mask Colors Available | Amber |  | ||
| Solder Mask Registration | Within 2 mil (0.0020 in/0.051 mm) | |||
| Solder Mask Feature Tolerance | 1 mil (0.0010 in/0.025 mm) | |||
| Solder Mask Minimum Dam Size | 3 mil (0.0030 in/0.076 mm)-4 mil (0.0040 in/0.102 mm) | |||
| Legend Colors Available | White | |||
| Surface Finishes Available | Recommended: ENIG (Electroless Nickel/Immersion Gold) Not recommended: HASL (Vertical or Horizontal), Lead-Free HASL, OSP (Shikoku F2 and Entek), and Immersion Silver. Others: Electrolytic Soft Gold, Electrolytic Hard Gold, and Selective Gold. | |||
| Mechanical Parameters | Mechanical Parameters | |||
|---|---|---|---|---|
| Maximum Panel Size | 18”x24” |     | ||
| Minimum Diameter Route Cutter Available | 19 mil (0.019 in/0.483 mm) | |||
| Mechanical Routed Part Size Tolerance | 3 mil (0.003 in/0.076 mm) | |||
| Routed Array | Yes | |||
| V Score, Edge to Copper | 5 mil (0.005 in/0.127 mm) | |||
| Countersink | No (Yes, if you have stiffeners) | |||
| Counterbore | No (Yes, if you have stiffeners) | |||
| Bevel | No | |||
| Milling | No | |||
| Edge Castellation | Yes | |||
| Edge Plating | Yes | |||
| Recommended Laminate Materials | Recommended Laminate Materials | ||||
|---|---|---|---|---|---|
| Flexible Poyimide | Iteq IT180 | Nelco BT N5000 | |||
| Isola FR406 | Panasonic R1766 | Nelco N7000-2 | |||
| Isola FR408 HR | Panasonic R1755 | Isola 370HR | |||
| Hitachi 671N | Nelco N4000-13 | PSA Bond Film | |||
| Arlon38N | Nelco N4000-29 | ||||
| PCB Testing and Reports | PCB Testing and Reports | |||
|---|---|---|---|---|
| Electrical Testing | 10 V, 40 V (burn-in boards), 250 V, and 500V |  | ||
| Microsection | Yes | |||
| Solderability | Yes | |||
| X-Ray Fluorescence | Yes | |||
| Ionic Contamination | Yes | |||
| Time Domain Reflectometry Test (TDR) | Yes | |||
| First Article Inspection (FAI) | Yes | |||
| Certificate of Compliance | Yes | |||
| PCB Certification | PCB Certification | |||
|---|---|---|---|---|
| MIL-PRF-55110 | No |  | ||
| MIL-PRF-31032/1 | No | |||
| MIL-PRF-31032/2 | No | |||
| IPC 6012, Class 1, 2 and 3 | Yes | |||
| ISO 9001:2015 | Yes | |||
| ISO 13485:2016 | Yes | |||
| UL (94VO) | Yes | |||
| Stack-Up | Stack-Up | |||
|---|---|---|---|---|
| Minimum Layer Count | 3 |  | ||
| Maximum Layer Count | ≤22 | |||
| Minimum Core Thickness | 2 mil (0.002 in/0.051 mm) | |||
| Maximum Finished Copper Thickness (inner layer) | 2 oz | |||
| Maximum Finished Copper Thickness (outer layer) | 2 oz | |||
| Thickness Tolerance (based on board thickness) | ±10% | |||
| Hybrid Constructions | Yes | |||
| No Flow Prepreg | Yes | |||
| Bow and Twist Tolerance | As per spec | |||
| Sequential Lamination | 3 lamination cycles | |||
| Drill and Pad | Drill and Pad | |||
|---|---|---|---|---|
| Minimum Finished Hole Size | 6 mil (0.0060 in/0.152 mm) |  | ||
| Smallest Mechanical Drill Diameter | 7.1 mil (0.0071 in/0.180 mm) | |||
| Smallest Laser Drill Diameter | 5 mil (0.0050 in/0.127 mm) | |||
| Minimum Annular Ring (only on rigid section) |
| |||
| Blind Vias | Yes | |||
| Buried Vias | Yes | |||
| Stacked Vias | No | |||
| Conductive Filled Vias | Yes | |||
| Non-Conductive Filled Vias | Yes | |||
| Maximum Through Hole Aspect Ratio (Depending on the board thickness and finished hole) | 10:1 | |||
| Maximum Laser Via Aspect Ratio | 0.75:1 | |||
| Minimum Pad Size for Test | 5 mil (0.0050 in/0.127 mm) | |||
| Process Pad Diameter | D + 0.014"(0.356 mm) (1-mil (0.025mm) annular ring) | |||
| Minimum Wire Bond Pad Size | >6 mil (0.0060 in/0.152 mm) | |||
| Backdrill to Copper Clearance | 10 mil (0.010 in/0.254 mm) | |||
| Backdrill to Backdrill Clearance | 6 mil (0.0060 in/0.152 mm) | |||
| Minimum Backdrill Oversize Diameter | 8 mil (0.0080 in/0.203 mm) to 10 mil (0.010 in/0.254 mm) | |||
| Minimum Controlled Depth Drilling | More than 1 mil (0.001 in/0.0254 mm) | |||
| Controlled Depth Drilling Tolerance | ±2 mil (0.002 in/0.0508 mm) | |||
| Trace and Spacing Clearances | Trace and Spacing Clearances | |||
|---|---|---|---|---|
| Minimum Trace Width | >=3.5 mil (0.0035 in/0.089 mm) (Rigid) | | ||
| Minimum Trace Spacing | >=3.5 mil (0.0035 in/0.089 mm) | |||
| Controlled Impedance Tolerance | ±10% for Standard and ±5% for Advanced | |||
| Solder Mask and Surface Finish | Solder Mask and Surface Finish | |||
|---|---|---|---|---|
| Solder Mask Colors Available | Amber, Green, Black, Purple, Red, Blue, Yellow, Bright White and Clear | | ||
| Solder Mask Registration | Within 2 mil (0.0020 in/0.051 mm) | |||
| Solder Mask Feature Tolerance | 1 mil (0.0010 in/0.025 mm) | |||
| Solder Mask Minimum Dam Size |
| |||
| Legend Colors Available | White | |||
| Surface Finishes Available | ENIG (Electroless Nickel/Immersion Gold), HASL(Vertical or Horizontal), Lead-Free HASL, OSP, Immersion Silver, Electrolytic Soft Gold, Electrolytic Hard Gold, and Selective Gold. | |||
| Mechanical Parameters | Mechanical Parameters | |||
|---|---|---|---|---|
| MaximumPanel Size | 18”x24” | | ||
| Minimum Diameter Route Cutter Available | 24 mil (0.024 in/0.610 mm) | |||
| Mechanical Routed Part Size Tolerance | +/-10% | |||
| Routed Array | Yes | |||
| V Score, Edge to Copper | 10 mil (0.0100 in/0.254 mm) | |||
| Countersink | Yes | |||
| Counterbore | Yes | |||
| Bevel | Yes | |||
| Milling | Yes | |||
| Edge Castellation | Yes | |||
| Edge Plating | Yes | |||
| Recommended Laminate Materials | Recommended Laminate Materials | ||||
|---|---|---|---|---|---|
| Flexible Poyimide | Iteq IT180 | Nelco BT N5000 | |||
| Isola FR406 | Panasonic R1766 | Nelco N7000-2 | |||
| Isola FR408 HR | Panasonic R1755 | Isola 370HR | |||
| Hitachi 671N | Nelco N4000-13 | PSA Bond Film | |||
| Arlon38N | Nelco N4000-29 | ||||
| PCB Testing and Reports | PCB Testing and Reports | |||
|---|---|---|---|---|
| Electrical Testing | 10 V, 40 V (burn-in boards), 250 V, and 500V | | ||
| Microsection | Yes | |||
| Solderability | Yes | |||
| X-Ray Fluorescence | Yes | |||
| Ionic Contamination | Yes | |||
| Time Domain Reflectometry Test (TDR) | Yes | |||
| First Article Inspection (FAI) | Yes | |||
| Certificate of Compliance | Yes | |||
| PCB Certification | PCB Certification | |||
|---|---|---|---|---|
| MIL-PRF-55110 | No | | ||
| MIL-PRF-31032/1 | No | |||
| MIL-PRF-31032/2 | No | |||
| IPC 6012, Class 1, 2 and 3 | Yes | |||
| ISO 9001:2015 | Yes | |||
| UL (94VO) | Yes | |||
How to place an Order for your Flex and Rigid-flex PCBs
Trusted by innovators
Engineers at the worlds most innovative companies choose Sierra Circuits for the highest quality flex and rigid-flex PCB manufacturing and assembly, right here in the USA.
Manufacturing Equipment at Sierra Circuits
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.
Get started with Flex and Rigid-Flex PCBs
We can turn your standard technology PCBs in as fast as in 24 hours.
Start a Custom Quote
Fabrication, Procurement, & Assembly. PCBs fully assembled in as fast as 5 days.
- Bundled together in an entirely-online process
- Reviewed and tested by Engineers
- DFA & DFM Checks on every order
- Shipped from Silicon Valley in as fast as 5 days
Fabrication. Procurement & Assembly optional. Flexible and transparent for advanced creators.
- Rigid PCBs, built to IPC-6012 Class 2 Specs
- 2 mil (0.002″) trace / space
- DFM Checks on every order
- 24-hour turn-times available
Complex technology, with a dedicated CAM Engineer. Stack-up assistance included.
- Complex PCB requirements
- Mil-Spec & Class 3 with HDI Features
- Blind & Buried Vias
- Flex & Rigid-Flex boards