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FLEXIBLE PRINTED CIRCUITS
Flexible PCBManufacturing
Single-sided, double-sided and multilayer FPC for compact interconnects. SLLPCB supports engineering prototypes and volume production, with construction reviewed against your electrical and mechanical requirements.
Engineering prototypes · Volume production
Flexible circuit sample · Contact areas and branched routing
01 · OVERVIEW
What Is a
Flexible PCB?
A flexible PCB, or FPC, carries copper circuits on a flexible insulating substrate, typically polyimide. A coverlay protects the conductors while leaving openings for solder pads and contacts. Local stiffeners add support at connectors or component areas without making the whole circuit rigid. Flexible circuits can fold into an enclosure or connect parts at different angles. Their construction must match the electrical layout, assembly method and bending conditions, especially when the circuit will move repeatedly.
Copper routing, contact areas and coverlay openings in an FPC sample.
02 · STRUCTURES
Flexible PCB Types
01
Single-Sided FPC
ONE COPPER LAYER
One conductive layer on a flexible substrate. A practical choice for simpler routing, thin interconnects and assemblies that fold into position.
02
Double-Sided FPC
TWO COPPER LAYERS
Copper circuits on both sides of the flex dielectric, with interconnections where specified. Suits designs that need more routing space within the same outline.
03
Multilayer FPC
MULTIPLE COPPER LAYERS
Multiple copper layers separated by flexible dielectric. Supports more complex interconnects; layer count and bend areas are reviewed together with the stackup.
Need rigid component areas connected by flex? Explore Rigid-Flex PCB →
03 · TECHNICAL REFERENCE
Flexible PCB Manufacturing
Capabilities
These are separate reference limits and may not apply together to one FPC. Copper thickness and layer construction affect which features can be manufactured. Submit the stackup, copper requirements and fabrication drawing for a project-specific review.
| Feature | Capability / specification |
|---|---|
| FPC constructions | Single-sided, double-sided and multilayer flexible circuits; up to 20 copper layers. |
| Flexible-area thickness | 0.06–1.0 mm |
| Copper thickness | 1/7–12 oz |
| Minimum line / space | 50 / 50 µm |
| Minimum line width | 50 µm |
| Minimum mechanical hole | 0.15 mm |
| Maximum processing dimensions | Width: 900 mm; length: 2100 mm |
| Outline and registration tolerances | Specified on the fabrication drawing and agreed for the selected construction. |
| Coverlay | Flexible coverlay with openings defined around component pads and contact areas. |
| Local stiffeners | PI, FR-4 and stainless steel, selected to meet local support and connector thickness requirements. |
| Surface finishes | ENIG, ENEPIG, immersion tin, immersion silver, OSP, electroplated gold and hard gold; selected for soldering or contact requirements. |
Thickness for quotation: state flex-only thickness separately from the finished connector or reinforced area. Include the stiffener and bonding adhesive in the local build-up, with the required tolerance.
04 · BENDING REQUIREMENTS
Static and Dynamic
Flex Requirements
Static / installation flex
The circuit bends during assembly or installation and remains in position. Review the installed radius, fold locations and clearance around supported areas.
Dynamic / repeated movement
The circuit moves repeatedly in service. Review the copper, stackup and moving section against the actual motion. Bend life depends on the construction and test conditions; it is not a single rating for every FPC.
Include with the RFQ: bend radius, bend direction, expected cycle count, motion range and operating environment.
05 · SAMPLE PHOTOGRAPHS
Flexible PCB Samples
and Applications
Branched interconnect
Visible features: routed branches, contact pads and local support areas. This layout illustrates connections to several locations within a compact assembly.
Display interconnect
Sample marking: DK-TFT2.0-A REV C. The contact row is marked 1–36; the photograph shows the connector tail and component pad openings.
06 · ACCEPTANCE & VERIFICATION
FPC Inspection
and Verification
Specify inspection scope and required records for the actual construction and order. Fabrication acceptance and application qualification should be agreed separately.
Fabrication acceptance
Confirm the required visual, dimensional and electrical checks in the order’s inspection plan. Include pad and contact openings, circuit outline and finished connector thickness in the agreed drawing.
Project-specific verification
Bending or environmental validation requires an agreed method and acceptance criteria. For bend-life work, define the construction, fixture, radius, motion and cycle target, together with the report required.
What files are needed for an FPC quote?
Send Gerber files, drill data, the proposed stackup and a mechanical drawing. Include stiffener locations and materials, contact thickness, surface finish, quantity and bend requirements. Add BOM and placement data if assembly is required.
How should stiffeners be specified?
Mark each stiffener’s material, thickness, outline, position and adhesive on the mechanical drawing. Identify whether the stated thickness is the stiffener alone or the complete reinforced area.
What thickness should I specify for a connector?
Use the connector datasheet to define finished thickness and tolerance at the mating contacts. The local build-up can include the flex laminate, copper, coverlay, bonding adhesive and stiffener; provide the full section rather than a nominal flex thickness alone.
Can every FPC be used for dynamic bending?
Dynamic use needs a construction reviewed for the actual movement. Provide bend radius, direction, cycle target and environment. A result for one sample or fixture does not define the life of a different stackup or motion.
How is the lead time confirmed?
Lead time is confirmed after reviewing the files, material availability, layer stackup, quantity, surface finish and inspection requirements. Include the required delivery date and destination, and distinguish fabrication from shipping time.
START YOUR FPC PROJECT
Request a
Flexible PCB Quote
Send the design files and the requirements below for review. Use the form to describe your project; email the fabrication files to sales@sllpcb.com.
- Gerber files and drill data
- Layer stackup and mechanical drawing
- Stiffener positions, materials and local thickness
- Quantity, finish and delivery requirements
- Bend radius, direction, cycle target and environment
