3 Layer Flex PCB

Place of OriginChina
CertificationUL , ISO9001
Minimum Order Quantity1pcs
Packaging DetailsVacuum
Delivery TimeFastest 24 hours for prototype
Payment Terms T/T



3 layer flexible circuit boards comprise an inner layer and two outer layers. that pressed together, and the surface treatment utilizes an immersion gold process. that provides excellent solderability, making ability. which makes them ideal for high-precision and high-demand electronics.



Focus on PCB fabrication Nearly 20 Years! GESFLEX FEATURED SERVICES FOR FLEX PCB

  • More than 10 years of flexible PCB manufacturing experience;
  • Provide with 1-10 layer flexible circuit board fabrication service;
  • Comply with ISO9001 & IPC level 2 or 3 standards
  • Provide fast turn multilayer flexible PCB prototype services;
  • The thickness of the multilayer FPC is 0.05-2.5mm, and the copper thickness is 1/3oz-2oz;
  • Supply 7*24 hours of sales, technical, and after-sales service support.

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The material used for the flexible substrate in a 3-layer flex PCB is a critical component. that provides the required flexibility and insulation. The most commonly used materials for flexible substrates in flex PCBs are:

Polyimide (PI):

This is our primary substrate material. It offers excellent thermal stability, flexibility, and mechanical strength. Polyimide withstands high temperatures and bends without cracking. making it ideal for complex designs.

Adhesive Materials

We use acrylic-based or epoxy-based adhesives. These provide strong adhesion and maintain flexibility. Acrylic-based adhesives resist heat and chemicals.

Copper Foil

We use high-purity copper foil for the conductive layers. Copper ensures excellent electrical conductivity, allowing for efficient signal transmission and power distribution.


This protective layer, made of polyimide or polyester films. shields the copper traces from moisture, dust, and mechanical damage. It also provides insulation and maintains the PCB’s flexibility.

Protective Coatings:

Solder masks and conformal coatings protect the PCB from oxidation, corrosion, and short circuits. These coatings cover everything except the solder pads. providing insulation and protecting the copper.


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3 layer flex pcb

Top Layer:

The top layer is where most components placed and where most electrical connections are made. It’s the outermost layer of the PCB and is typically made of flexible substrate material like polyimide. This layer allows the PCB to bend and flex without harming the components.

Inner Layer:

Positioned between the top and bottom layers. the inner layer offers additional routing space for traces and components. It plays a key role in maintaining the structural integrity of the PCB. and ensures efficient distribution of electrical signals. Just like the top layer, it’s made of flexible material.

Bottom Layer:

Similar to the top layer, the bottom layer hosts components and traces. It completes the circuitry of the PCB and provides extra mechanical support. Like the other layers, it’s made of flexible material to preserve the board’s flexibility.

In essence, the 3-layer flex PCB stackup comprises. alternating layers of flexible substrate material and conductive traces. These layers laminated together to form a cohesive and flexible circuit board. enabling it to bend and adapt to different shapes while maintaining functionality. This makes it perfect for applications that require both flexibility and durability.

3 layer flexible circuit

3-Layer Flex Circuit Success Cases

  • Design: 3-layer structure
  • Finished Thickness: 0.2mm
  • Materials: Double-sided non-adhesive electrolytic copper + single-sided non-adhesive electrolytic copper
  • Copper Thickness: 1/3 oz
  • Surface Treatment: Immersion Gold 2 microinches
  • Minimum Line Width/Spacing: 0.1mm / 0.1mm
  • Minimum Drill Hole: 0.15mm
  • Total Thickness of Steel Plate Reinforcement: 0.4mm

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quick turn flex pcb prototyping quality assurance AOI test
  • UL certification.
  • ISO9001:2008 quality certification.
  • Fabrication according to IPC6012 standard.
  • Strict management for customer confidentiality.


flexible pcb board manufacturing process-design

Step1: Design and Material Selection:

The first step is to design the circuit and determine the specific requirements for the  flex PCB. This includes deciding on the number of layers. stack-up configuration, trace routing, component placement, and material selection.

Step2: Material Preparation:

The chosen flexible substrate material, typically polyimide. That supplied in rolls or sheets and undergoes a cleaning process. to remove any contaminants that could affect the bonding. or adhesion of subsequent layers.

flexible pcb board manufacturing process-material prepartion
flexible pcb board manufacturing process-copper cladding

Step3: Copper Cladding

The polyimide sheets coated with a layer of copper. This involves laminating a thin layer of copper foil. onto the polyimide surface using heat and pressure. The copper etched to remove excess material, leaving behind the desired copper traces.

Step4: Imaging and Etching

A photoresist applied to the copper layer. and the circuit pattern transferred onto it using a photomask and UV exposure. The exposed areas are then chemically etched. removing the unwanted copper, and leaving behind the desired circuit traces.

flexible pcb board manufacturing process-etching
flexible pcb board manufacturing process-drilling

Step5: Drilling and Plating

Small holes called vias drilled through the polyimide. and copper layers at specific locations to provide interconnections between different layers. The vias are then plated with a conductive material. such as copper or electroless nickel to ensure electrical continuity.

Step6 : Lamination

The individual layers, including the conductive layers and insulating layers. stacked together and laminated under heat and pressure. An adhesive layer, often made of epoxy, Used to bond the layers together. This process forms a layer structure with the desired stack-up configuration.

flexible pcb board manufacturing process- lamination
flexible pcb board manufacturing process-Coverlay

Step7 : Coverlay Application

A coverlay, which is a protective layer made of polyimide, applied on top of the circuitry. It bonded to the flexible PCB using heat and pressure. The coverlay protects the circuit traces from environmental factors and provides insulation.

Step 8 : Surface Finishing

The exposed copper pads on the outer layers plated with a surface finish. such as electroless nickel immersion gold (ENIG). to protect them from oxidation and facilitate soldering during assembly.

flexible pcb board manufacturing process-surface finishing
flexible pcb board manufacturing process-testing

Step 9 : Testing and Inspection

The manufactured flexible PCB undergoes testing and inspection. to ensure it meets the required specifications and quality standards. This includes electrical testing, impedance measurement, visual inspection. and possibly other specific tests depending on the application.

Step 10 : Assembly and Integration

The completed flex PCB is then integrated into the electronic device or assembly. Components soldered onto the board. and any additional mechanical or electrical connections made as necessary.

flexible pcb board manufacturing process-assembly

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Professional One-stop Flexible PCB & FPC Services RELIABLE FLEX PCB BOARD MANUFACTURER

IF you are looking for high quality flexible pcb board. and flexible pcb board for your projects. GESFLEX CIRCUITS is a good choice as a competitive China flexible pcb board. We have been making flex PCBs for large volume production as well as prototypes since the 2014. We use unique, custom-built tools that give us the edge over our competitors. Beacuse rich experience, advanced equipment, stable PCB fabricaition. strict quality control all represent our strength . you can upload your Gerber files to our cloud, for an instant quote.

flex pcb fabrication