Custom Multilayer Flex Circuit Fabrication
Multilayer Flexible PCB Manufacturing
Custom multilayer flex circuits up to 16 layers for prototype and production orders. PCBELEC manufactures defined stackups, layer interconnections and locally engineered flexible regions, with specified materials, coverlay and reinforcement.
Send your fabrication package to sales@pcbelec.com
- Manufacturing Capability Up to 16 Copper Layers
- Construction Features Stackups & Interconnections
- Order Stages Prototypes to Production
Multilayer Flexible Circuits / Multilayer FPC
What Is a Multilayer Flex PCB?
A multilayer flex PCB contains three or more conductive copper layers separated by flexible insulating materials. The construction combines internal and external circuit layers with the interconnections defined for the design.
Compared with double-sided flex PCBs, additional copper layers provide more options for routing, power distribution and reference structures within the specified board format.
PCBELEC manufactures multilayer flexible circuits up to 16 layers as part of our flexible PCB fabrication service. Define the overall stackup together with the construction of each flexible and supported region.
Organize More Connections
Distribute the specified connections across additional conductive layers instead of concentrating all routing on two surfaces.
Define Reference Structures
Assign signal, ground and power functions within the stackup to support the electrical requirements.
Engineer the Flexible Regions
Define local layer continuity, bonding, thickness and support around the product’s mechanical interfaces.
Layer Arrangement & Electrical Connections
Multilayer Flex Stackups and Interconnections
A multilayer flex stackup defines the copper sequence, insulating materials, bonding layers and interconnections. Assign the electrical function of each layer alongside the construction of the flexible regions.
Illustrative Layer Structure
4-Layer Flex Stackup
Illustrative Layer Structure
6-Layer Flex Stackup
- Conductive copper
- Insulation / bonding
- Protective construction
Layer-to-Layer Connections
Define which layers each interconnect joins. A plated-through barrel can extend through the full construction while clearances isolate copper layers that must not connect to it.
Signal & Reference Layers
Identify the reference structures for critical signals. Pair impedance targets with trace geometry, material properties, copper and dielectric spacing.
Region-Specific Construction
Show the layers and bonding arrangement present in each region. A single overall layer count does not describe every local thickness, transition or flexible span.
Multilayer Circuit Fabrication Specifications
Multilayer Flex PCB Manufacturing Capabilities
PCBELEC manufactures multilayer flexible circuits up to 16 layers, combining polyimide materials, defined interconnections, coverlay and local reinforcement with the specified electrical and mechanical requirements.
- Conductive Layers Up to 16 Layers
- Maximum Board Size 236 × 600 mm
- Construction Options Bonded & Air-Gap
Swipe horizontally to view all manufacturing specifications.
| Capability Item | Construction / Process | Manufacturing Specification |
|---|---|---|
| Conductive Layers | Multilayer flexible circuits | Up to 16 copper layers |
| Base Materials | Polyimide laminate systems | DuPont PI / Shengyi PI |
| Maximum Board Size | Multilayer flexible PCB format | 236 × 600 mm |
| Finished Thickness | Overall and region-specific construction | Built to the specified stackup and local thickness requirements |
| Minimum Trace / Space | 1/3 oz or 1/2 oz copper; 3–6 layer builds | 0.076 / 0.076 mm |
| Minimum Trace / Space | 1 oz copper; 3–6 layer builds | 0.10 / 0.10 mm |
| Minimum Trace / Space | 1/3 oz copper; 8-layer build | 0.05 / 0.05 mm |
| Minimum Trace / Space | 1/2 oz copper; 8-layer build | 0.06 / 0.06 mm |
| Minimum CNC-Drilled Hole | 3–6 layer builds | 0.20 mm |
| Minimum CNC-Drilled Hole | 8-layer build | 0.15 mm |
| Finished PTH Tolerance | Plated-through holes | ±0.038 mm |
| Coverlay Registration | Protective-film alignment | 0.10 mm registration tolerance |
| Local Reinforcement | Supported connection and component regions | PI / FR-4 stiffener construction |
| Air-Gap Construction | Defined non-bonded flexible regions | Available |
| Surface Finishes | Specified exposed pads and contacts | OSP, HASL, ENIG, flash gold and tin finishes |
| Controlled Impedance | Specified impedance structures | ±10% impedance-control capability |
| Profile Tolerance | Outline / contour | ±0.05 mm |
Define the Local Mechanical Construction
Flexible Regions, Bonded Layers and Air-Gap Structures
A multilayer circuit can use different bonding arrangements in designated regions. Define how the layers are joined, where flexible spans begin and how the circuit transitions into supported connection areas.
Bonded Multilayer Construction
The specified circuit layers and insulating materials are bonded together through the region. Define the complete local stackup, finished thickness and installed geometry.
- Continuous bonding within the defined region
- Specified copper, dielectric and bonding thicknesses
- Mechanical requirements tied to the complete stackup
Air-Gap / Locally Unbonded Construction
Selected flexible subcircuits remain unbonded to one another within a defined span. The separation allows relative movement between groups rather than making them one fully bonded laminate in that region.
- Defined non-bonded span and transition boundaries
- Individual subcircuit stackups and protective layers
- Specified separation, movement and attachment geometry
Describe Each Flexible Region in the Drawing
The overall layer count is only part of the mechanical definition. Show the local layers, bonding arrangement and transitions that determine the behavior of each span.
Layer Continuity
Identify which circuit layers and subcircuits extend through each flexible region.
Bonded & Unbonded Boundaries
Mark the start, end and transition geometry of each intentionally non-bonded span.
Local Thickness
Define the thickness of individual subcircuits separately from the overall installed envelope.
Bend & Movement Conditions
State the radius, direction, angle, motion and static or repeated-use condition.
Feature & Support Locations
Show vias, pads, stiffener edges, attachment points and nearby connection interfaces.
Evaluation Requirements
Define the mechanical test conditions, electrical checks and acceptance records.
An air-gap region is an intentional design feature, not laminate delamination. The drawing defines where separation is required and where bonding must be maintained.
Materials, Protection & Local Interfaces
Materials, Coverlay and Connection Support
Define the laminate system, protective layers and supported connection areas as one construction. The material stackup and mechanical drawing should identify both the circuit structure and the finished interfaces.
Polyimide, Copper & Bonding Layers
Our multilayer flex fabrication uses polyimide laminate systems with specified copper and bonding materials. Define each layer’s material and thickness instead of relying on the overall board thickness alone.
- Laminate grades and dielectric thicknesses
- Copper type and thickness by layer
- Adhesive-based or adhesiveless base construction
- Bonding materials and layer arrangement
Coverlay & Exposed Features
Coverlay protects designated circuit areas while openings expose pads and contacts. Connect the opening data to the copper geometry and the protective construction specified for each region.
- Coverlay film and adhesive thicknesses
- Pad and contact opening geometry
- Registration and clearance requirements
- Coverage at local construction transitions
Stiffeners & Supported Areas
Local reinforcement supports connector regions, contact tails and component-bearing areas. Define the stiffener separately from the conductive-layer structure and identify the finished thickness where it matters.
- Stiffener material and outline
- Attachment side and bonding method
- Finished local thickness
- Alignment and transition locations
Pads, Contacts & Surface Finish
Specify the finish on exposed soldering pads and connection contacts. Identify contact geometry and coating requirements separately from the circuit copper and flexible-region construction.
- Pad and contact finish type
- Coating thickness and selective areas
- Connector reference and contact side
- Required exposed contact dimensions
Verify the Multilayer Construction
Fabrication Quality and Inspection Records
PCBELEC combines circuit inspection, electrical verification and structural checks for multilayer flexible boards. Inspection connects the layer structure, interconnections and local features to the released manufacturing specification.
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01 / CIRCUIT LAYERS
Circuit Patterns & Layer Registration
Optical inspection examines manufactured copper features during fabrication. Registration checks address the alignment of the circuit layers and designated interconnection features.
- Internal and external circuit features
- Pad, clearance and interconnect alignment
- Visible finished-surface condition
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02 / ELECTRICAL NETWORK
Continuity, Isolation & Impedance
Electrical testing checks continuity and isolation in the manufactured network. Specified impedance structures are verified against their targets and tolerances.
- Open- and short-circuit testing
- Designated layer-to-layer connections
- Specified impedance verification and records
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03 / INTERNAL CONSTRUCTION
Plated Interconnects & Microsections
Cross-sectional inspection examines relevant plating, layer interfaces and interconnect construction within the manufactured board.
- Plated-hole and copper measurements
- Layer-interface and construction features
- Defined cross-sectional inspection locations
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04 / FINISHED MECHANICAL FEATURES
Coverlay, Reinforcement & Dimensions
Inspect the finished profile, protective layers, local support and interface geometry against the manufacturing drawing.
- Coverlay openings and contact areas
- Stiffener position and finished local thickness
- Outline, holes and defined region boundaries
Development Builds to Repeat Manufacturing
Multilayer Flex Prototypes and Production
PCBELEC manufactures multilayer flexible circuits for engineering evaluation, pilot builds and production orders. Keep the released stackup, regional construction and interface requirements connected as your project moves between builds.
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01 / ENGINEERING EVALUATION
Multilayer Flex Prototypes
Manufacture initial and revised multilayer circuits for your engineering evaluation, using the specified layer arrangement, interconnects and local construction.
- Defined stackup and material system
- Flexible-region and connection-area details
- Evaluation quantities and requested records
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02 / PILOT & SMALL-BATCH BUILDS
Low-Volume Flex Orders
Order multilayer flex circuits for pilot runs, early production and ongoing small-batch needs. Define the released revision, delivery format and inspection requirements for each order.
- Pilot and small production quantities
- Individual circuits or array delivery
- Handling, packaging and reporting needs
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03 / RELEASED DESIGNS
Production & Repeat Orders
Manufacture released multilayer flex designs for production quantities and repeat builds, with the specified materials, layer structure and local interfaces tied to the order.
- Released revisions and construction records
- Consistent materials and regional stackups
- Quantity and delivery planning
Custom Multilayer Circuit Quotation
Request a Multilayer Flex PCB Quote
Send the fabrication files, stackup, region definitions and order quantity to PCBELEC. Include the electrical and mechanical details that define your multilayer flexible circuit.
What Shapes the Fabrication Price?
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Circuit dimensions, quantity, outline complexity and manufacturing panel utilization.
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Layer count, material system, copper, dielectric and bonding construction.
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Interconnect structure, lamination sequence, routing geometry and controlled impedance.
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Air-gap regions, coverlay, reinforcement, contact finish and local thickness requirements.
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Verification records, delivery format, packaging, destination and requested schedule.
Include These Details with Your Inquiry
Manufacturing File RequirementsCircuit Files & Revision
Data for every conductive layer, drill files, profile, fabrication drawings and the required board revision.
Stackup & Interconnections
Layer names, material grades, copper, dielectric and bonding thicknesses, via spans and pad requirements.
Region Map & Local Construction
Bonded and air-gap boundaries, local layer continuity, flexible spans, thicknesses and transition details.
Coverlay, Stiffeners & Contacts
Opening data, reinforcement materials and locations, contact finish and connector-interface dimensions.
Electrical & Mechanical Verification
Impedance targets, critical tolerances, bend conditions, acceptance criteria and requested inspection records.
Quantity & Delivery
Prototype or production quantity, individual circuit or array format, packaging, destination and target date.
Multilayer Flexible Circuit Questions
Multilayer Flex PCB FAQ
Answers about conductive layers, stackups, interconnections, flexible regions and manufacturing inquiries.
Discuss your next multilayer flex build:
sales@pcbelec.comWhat makes a flexible PCB multilayer?
A multilayer flexible PCB has three or more conductive copper layers separated by flexible insulating materials. The construction includes internal and external circuit layers with the specified layer-to-layer connections.
Coverlay, adhesive and stiffeners are physical construction elements, not additional circuit layers. See the multilayer flex definition.
How many layers can PCBELEC manufacture?
PCBELEC manufactures multilayer flexible circuits up to 16 copper layers. Define the layer sequence, materials, interconnections and local construction in the manufacturing stackup.
Review the multilayer flex manufacturing capabilities for selected fabrication specifications.
Is there one standard 4-layer or 6-layer flex stackup?
No. Layer count identifies the number of conductive layers, but it does not define their electrical assignments, copper thicknesses, dielectric spacing or bonding arrangement.
Use the 4-layer and 6-layer examples to understand the layer sequence, then specify the complete stackup for your circuit.
What is an air-gap multilayer flex construction?
An air-gap construction leaves selected flexible subcircuits intentionally unbonded to one another within a defined span. Each subcircuit has its own specified insulation and protective construction.
The drawing identifies the separated span and bonded transitions. This intentional feature is different from laminate delamination. Compare bonded and air-gap regions.
Can a multilayer flex PCB be used for repeated bending?
Repeated movement is addressed through the construction of the moving region, including its local layers, copper, bonding arrangement, thickness and bend geometry.
Describe the motion, radius, expected cycles and evaluation requirements. The overall layer count alone does not establish bending life or a universal minimum bend radius.
What is the difference between multilayer flex and rigid-flex?
Multilayer flex describes a flexible circuit with multiple conductive layers. Rigid-flex integrates rigid circuit sections with flexible interconnections in one manufactured structure.
A local stiffener adds mechanical support without creating routed rigid circuit layers. Explore our rigid-flex PCB manufacturing service when the design requires integrated rigid circuit regions.
Can multilayer flex circuits include controlled impedance?
Yes. PCBELEC supports controlled-impedance multilayer flex fabrication. Specify the targets, tolerances, relevant signal layers and reference structures with the material and thickness stackup.
Identify the verification and reporting requirements in the manufacturing package. Review our detailed flex fabrication capabilities.
Do you support prototypes and repeat production?
Yes. PCBELEC manufactures multilayer flex prototypes, pilot builds, low-volume orders and repeat production. Each order identifies the released revision, construction, quantity and delivery requirements.
Explore our dedicated flex PCB prototyping service and the production options on this page.
What affects the cost of a multilayer flex PCB?
Cost reflects the size, quantity, layer count, materials, copper, bonding and interconnect structure. Air-gap regions, coverlay, stiffeners, contact finishes and critical tolerances also shape the manufacturing quote.
Include verification, packaging and schedule requirements when you request a multilayer flex PCB quotation.
Which files should I send for quotation and manufacturing?
Send data for each conductive layer, drill files, the profile, fabrication drawing and required revision. Include the stackup, via spans, materials and region-specific construction.
Add coverlay openings, stiffeners, contact details, bend requirements, quantity and delivery needs. Review the manufacturing file requirements before submitting the package.