# Rigid Flex Circuit

_Published: 2026-04-10_

Table of Contents

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- What Is a Rigid Flex Circuit?
- Our Typical Project Cases
- Rigid Flex PCB vs. Flex PCB with Stiffener
- Our Rigid Flex PCB Manufacturing Capabilities
- Common Rigid Flex Stack-Ups
- Special Rigid Flex Structures for Custom Applications
- Design and Manufacturing Considerations
- Typical Applications of Rigid Flex PCB
- Why Work With EBest Circuit (Best Technology) for Rigid Flex PCB?
- What Files Are Recommended for RFQ?
- FAQs
- Get a Quote for Your Rigid Flex Circuit Project

Rigid flex circuit is a PCB structure that combines rigid board sections and flexible circuit layers into one integrated unit. It offers the strength of [rigid FR4 boards](https://www.bestpcbs.com/products/FR4-pcb.htm) and the space-saving advantage of flexible circuits. Compared with a standard flex PCB with stiffeners, a true rigid flex board is built with plated through holes (PTH) that electrically connect the rigid and flexible layers inside the structure.

Rigid flex PCBs are widely used in medical devices, aerospace electronics, industrial controls, automotive systems, and advanced consumer products where stable performance and compact structure are required.

## What Is a Rigid Flex Circuit?

A rigid flex circuit is a hybrid PCB made by laminating rigid substrates and flexible substrates into one board structure. The rigid sections support component mounting, while the flexible sections allow bending or folding during installation.

This design helps engineers reduce assembly size, simplify internal wiring, and improve product reliability. Instead of using multiple separate boards connected by cables or connectors, a rigid flex PCB combines these functions into one integrated interconnection platform.

**Main Features of Rigid Flex PCB**

- Combines rigid and flexible substrates in one board
- Uses plated through holes for internal electrical interconnection
- Supports compact and three-dimensional assembly design
- Reduces connectors, cables, and manual soldering points
- Improves reliability in high-vibration and limited-space applications

![Rigid Flex Circuit](https://www.bestpcbs.com/blog/wp-content/uploads/2026/04/rigid-flex-pcb.png)

**Rigid Flex Circuit**

## Our Typical Project Cases

**Case 1 – Medical Portable Monitoring Device Rigid Flex PCB**

**Application:** Portable medical monitoring system

**Board Type:** 6 Layer Rigid Flex PCB

**Material:** FR4 + Polyimide

**Surface Finish:** ENIG

**Key Requirement:** Compact size, stable signal, high reliability

[https://www.bestpcbs.com/blog/wp-content/uploads/2026/04/99eedb7a4d5e495a9e68613dbbded519-1.png](https://www.bestpcbs.com/blog/wp-content/uploads/2026/04/99eedb7a4d5e495a9e68613dbbded519-1.png)

**Case 2 – Automotive Camera Module Rigid Flex PCB**

**Application:** Automotive camera system

**Board Type:** 4 Layer Rigid Flex PCB

**Material:** High Tg FR4 + Polyimide

**Surface Finish:** ENIG

**Key Requirement:** Vibration resistance, compact structure

[https://www.bestpcbs.com/blog/wp-content/uploads/2026/04/bb9de1c505c047d2bdc1309a02b0a83c.png](https://www.bestpcbs.com/blog/wp-content/uploads/2026/04/bb9de1c505c047d2bdc1309a02b0a83c.png)

**Case 3 – Industrial Control System Rigid Flex PCB**

**Application:** Industrial control module

**Board Type:** 8 Layer Rigid Flex PCB

**Material:** FR4 + Polyimide

**Surface Finish:** ENIG

**Key Requirement:** High density routing, stable interconnection

[https://www.bestpcbs.com/blog/wp-content/uploads/2026/04/cc27b2c73d97420c8878dec1ab0842db.png](https://www.bestpcbs.com/blog/wp-content/uploads/2026/04/cc27b2c73d97420c8878dec1ab0842db.png)

**Case 4 – Consumer Electronics Folding Device Rigid Flex PCB**

**Application:** Foldable consumer electronic device

**Board Type:** 4 Layer Rigid Flex PCB

**Material:** FR4 + Polyimide

**Surface Finish:** ENIG

**Key Requirement:** Repeated bending, compact layout

[https://www.bestpcbs.com/blog/wp-content/uploads/2026/04/ea89aa1f03524f978deef3d46de82769.png](https://www.bestpcbs.com/blog/wp-content/uploads/2026/04/ea89aa1f03524f978deef3d46de82769.png)

## Rigid Flex PCB vs. Flex PCB with Stiffener

A [rigid flex circuit](https://www.bestfpc.com/Products/Rigid_Flex_PCB/) is different from a flex PCB with FR4 or polyimide stiffeners.

In a flex PCB with stiffener, the stiffener is added only for local support. It is usually attached by adhesive and does not provide plated electrical interconnection between layers.

In a rigid flex PCB, the rigid and flexible sections are laminated into one complete structure, and the layers are electrically connected through plated through holes. This gives the board stronger structural integrity and better long-term reliability.

**Key Difference**

**Item**
**Rigid Flex Circuit**
**Flex PCB with Stiffener**

Structure
Integrated rigid and flex laminate
Flex circuit with added support layer

Electrical Interconnection
Yes, through plated holes
No plated interconnection through stiffener

Mechanical Stability
Higher
Moderate

Assembly Integration
Better
Limited

Typical Use
High-reliability compact products
Local reinforcement only

## Our Rigid Flex PCB Manufacturing Capabilities

Below is a typical reference table for custom rigid flex PCB manufacturing capability.

**Parameter**
**Typical Capability**

Rigid Flex Structure
Single-sided, double-sided, multilayer rigid flex

Base Materials
FR4 + Polyimide

Layer Count
2L to 50L

Rigid Layer Material
Standard FR4 / High Tg FR4

Flexible Layer Material
Polyimide (PI)

Copper Thickness
0.5 oz to 4 oz

Board Thickness
Custom build-up

Flex Thickness
Based on stack-up design

Min Line / Space
4/4 mil

Min Drill Hole
0.2 mm

Surface Finish
ENIG, HASL, OSP, Immersion Tin, Immersion Silver

Solder Mask
Green, Black, White, Red, Blue, Yellow

Coverlay
Yellow / Black / White

Stiffener Option
FR4, PI, Stainless Steel

Impedance Control
Supported

Via Type
PTH, blind via, buried via, microvia based on design

Assembly Service
PCB fabrication + SMT assembly

Production Type
Prototype to mass production

Assembly Support
SMT, THT, mixed technology assembly

File Support
Gerber, drill file, stack-up, assembly drawing, BOM

## Common Rigid Flex Stack-Ups

Rigid flex PCB structures are usually designed as multilayer constructions. The final stack-up depends on routing density, bend radius, thickness target, and mechanical design requirements.

**4 Layer Rigid Flex**

**Option 1**

- 1L FR4
- 2L FPC
- 1L FR4

**Option 2**

- 2L FR4
- 2L FPC

**6 Layer Rigid Flex**

**Option 1**

- 2L FR4
- 2L FPC
- 2L FR4

**Option 2**

- 1L FR4
- 4L FPC
- 1L FR4

**8 Layer Rigid Flex**

**Option 1**

- 2L FR4
- 4L FPC
- 2L FR4

**Option 2**

- 1L FR4
- 6L FPC
- 1L FR4

**Option 3**

- 2L FPC
- 4L FR4
- 2L FPC

**Option 4**

- 1L FPC
- 6L FR4
- 1L FPC

## Special Rigid Flex Structures for Custom Applications

Besides standard multilayer designs, some projects require custom rigid flex configurations for special packaging or functional needs.

**2 Layer Rigid Flex**

- 1L FR4
- 1L FPC

**3 Layer Rigid Flex**

**Option 1**

- 1L FR4
- 1L FPC
- 1L FR4

**Option 2**

- 1L FPC
- 1L FR4
- 1L FPC

These special designs are often used in compact electronic modules where a simple but integrated board structure is needed.

## Design and Manufacturing Considerations

A reliable rigid flex PCB depends not only on layout, but also on manufacturability planning. Early engineering review can help avoid cracking, delamination, poor bend performance, and assembly issues.

**Key Points to Consider**

- Stack-up design between rigid and flex areas
- Bend radius and bending direction
- Copper balancing in flex zones
- Coverlay opening design
- Stiffener placement
- Hole location near bend areas
- Final thickness control
- Component placement on rigid sections only
- Impedance and signal path planning for high-speed designs

A good rigid flex supplier should review these details before production, not after problems appear.

## Typical Applications of Rigid Flex PCB

- Medical monitoring and portable diagnostic devices
- Aerospace and defense electronics
- Industrial control systems
- Automotive electronic modules
- Cameras and optical devices
- Consumer electronics with compact internal layouts

## Why Work With EBest Circuit (Best Technology) for Rigid Flex PCB?

EBest Circuit provides custom rigid flex PCB manufacturing for projects that require compact structure, stable interconnection, and reliable quality. With over 20 years of PCB experience, we support customers from design review to fabrication and assembly.

**What We Offer**

- Custom rigid flex PCB fabrication
- Stack-up review and DFM support
- PCB and PCBA one-stop service
- Prototype and volume production support
- Material and process suggestion based on application
- Fast response for RFQ and engineering questions

Our engineering team understands the practical challenges behind rigid flex structures and helps customers improve both design feasibility and production stability.

## What Files Are Recommended for RFQ?

To speed up quotation and technical review, it is helpful to provide:

- Gerber files
- Drill files
- Stack-up information
- Fabrication drawing
- Assembly drawing
- BOM list
- Pick and place file if assembly is needed

Clear documentation helps reduce back-and-forth communication and improves quote accuracy.

## FAQs

**1. What is the minimum bend radius for rigid flex PCB?**

The bend radius depends on the flex thickness and copper structure. A common guideline is:

- Single-layer flex: 6–10 × thickness
- Double-layer flex: 10–15 × thickness
- Multilayer flex: 15–20 × thickness

Proper bend radius design is critical to prevent copper cracking or delamination during use.

**2. Can components be placed on the flexible area?**

In most cases, components should be mounted only on the rigid sections.

Placing components on flex areas is possible in special designs, but it requires careful reinforcement, controlled bending conditions, and additional manufacturing considerations. For standard designs, keeping components on rigid areas improves reliability and assembly stability.

**3. What materials are used in rigid flex PCB?**

Rigid flex circuits typically use:

- Rigid layers: FR4 or high Tg FR4
- Flexible layers: Polyimide (PI)
- Coverlay: Polyimide film with adhesive
- Stiffeners: FR4, PI, or stainless steel

Material selection depends on temperature requirements, bending cycles, and electrical performance.

**4. How many bending cycles can a rigid flex PCB withstand?**

The bending life depends on the design and materials. With proper design, rigid flex circuits can withstand thousands to millions of bending cycles.

Key factors include:

- Copper thickness
- Flex layer structure
- Bend radius
- Material quality

Engineering optimization is important for applications requiring repeated movement.

## Get a Quote for Your Rigid Flex Circuit Project

Looking for a reliable rigid flex PCB manufacturer for your next project? Best Technology can support your design with engineering review, custom stack-up guidance, and stable production service.

Send your Gerber files, stack-up details, or project requirements to **sales@bestpcbs.com** for quotation and technical support.