8-Layer ENIG Smartwatch-Specific Rigid-Flex PCB

Designed exclusively for premium smartwatches, this 8-layer rigid-flex PCB combines FR4 rigid boards with FPC (Flexible Printed Circuit) technology, delivering high-density routing, bend resistance, lightweight construction, and ultra-thin profiles.

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Product Description

Product Overview

Designed exclusively for premium smartwatches, this 8-layer rigid-flex PCB combines FR4 rigid boards with FPC (Flexible Printed Circuit) technology, delivering high-density routing, bend resistance, lightweight construction, and ultra-thin profiles. Featuring ENIG (Electroless Nickel Immersion Gold) surface treatment and precision circuitry, it ensures stable signal transmission and soldering reliability, ideal for multi-functional integration in smartwatch sensors, displays, charging modules, and more.

 

Product Features

1. 8-Layer High-Density Interconnect 

   Supports complex layouts for multi-sensor systems, Bluetooth/WiFi modules, and battery management with high-speed signal integrity.  

 

2. Hybrid FR4+FPC Construction 

   Rigid sections provide mechanical stability, while flexible zones conform to curved watch designs, enhancing durability and space efficiency.  

 

3. ENIG Surface Finish

   Superior oxidation resistance and flat solder pads ensure high yield for micro BGA/QFN components and gold wire bonding compatibility.  

 

4. Ultra-Precise Circuitry

   0.26mm minimum line width/spacing enables high-precision impedance control, minimizing signal loss and crosstalk.  

 

5. Black Solder Mask + White Silkscreen

   UV-resistant black solder mask paired with crisp white silkscreen improves assembly accuracy and aesthetic appeal.

 

Technical Specifications

Layers

8 Layers (4 Rigid + 2 Flex + 2 Rigid)

Base Material

FR4 (Rigid) + PI-based FPC (Flex)

Thickness

0.8mm±0.1mm (Finished Board)

Copper Weight

1oz (Outer) / 0.5oz (Inner)

Solder Mask Color

Black Matte

Silkscreen Color

White

Surface Finish

ENIG (Electroless Nickel Immersion Gold)

Min. Line Width/Spacing

0.26mm/0.26mm

Min. Hole Size

0.4mm (Mechanical Drilling)

Solder Mask Coverage

Full Coverage (Excluding Pads)

Impedance Control Tolerance

±10%

 

Application Areas

Premium Smartwatches: Main processor-to-sensor connections, flexible display drivers, wireless charging interfaces.  

Medical-Grade Wearables: Stable signal transmission for heart rate/SpO₂/ECG monitoring modules.  

Fitness Trackers: High-frequency routing for GPS antennas and motion sensors.  

 

Special Production Process

1. Multi-Layer Lamination  

   High-temperature/pressure bonding ensures defect-free rigid-flex transitions.  

2. ENIG + Selective Gold Plating  

   Localized gold plating on flex areas enhances bend cycles; ENIG guarantees solderability.  

3. Laser Drilling + Precision Etching  

   0.4mm micro-vias and 0.26mm line accuracy support miniaturized component layouts.  

4. AOI + Flying Probe Testing  

   100% electrical testing and impedance verification compliant with IPC-6013D Class 3 standards.  

 

Product Summary

 

This 8-layer rigid-flex PCB with ENIG finish addresses the core demands of smartwatches for ultra-thin designs, high reliability, and multi-functional integration, optimizing both battery life and signal integrity. Verified through mass production by industry leaders, its 0.8mm slim profile and 100,000+ bend-cycle durability make it the ultimate solution for premium wearable electronics.  

 

 

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