Rigid-Flex PCB Fabrication Capabilities
Rigid-Flex PCB Fabrication Capabilities
PCBELEC manufactures rigid-flex PCBs with 2–32 total layers, including 1–12 flexible layers. Flex-region trace/space capability reaches 4/4 mil at 0.5 oz copper. Controlled impedance is available at ±10% for mass production and ±7% for prototype or extended review, subject to the specified stackup and test requirements.
Rigid and flexible regions have different process limits. Share your layer map, stackup and flex-region requirements for an engineering review.
Manufacturing Overview
Rigid-Flex Capabilities by Region and Production Window
Rigid and flexible sections have different process limits. This overview highlights key construction, conductor and impedance capabilities; use the detailed tables below for additional specifications and application notes.
| Process area | Capability | Conditions and definitions |
|---|---|---|
| Total rigid-flex layers | 2–32 layers | Flexible layers are included in the total layer count. |
| Flexible layers within the stack | 1–12 layers | Identify which copper layers continue through each flexible region. |
| Flex-region minimum trace / space |
0.5 oz: 4 / 4 mil 1 oz: 5 / 5 mil 2 oz: 5 / 7 mil | Use the value corresponding to the flexible-region copper weight. |
| Rigid-region minimum line width / spacing | 3 / 3 mil | Applies to rigid regions; these are not flexible-tail design rules. |
| Controlled impedance |
Mass production: ±10% Prototype / extended review: ±7% | Define target impedance, signal and reference layers, test coupon and test method. |
| Minimum mechanical drill | 0.10 mm drill / process-entry size | Specify finished-hole diameter separately; it is not the same dimension as drill size. |
| Rigid-region heavy copper | 4 oz nominal; up to 12 oz | Heavy-copper limits apply to rigid-region construction, not automatically to flexible tails. |
The listed limits apply to their stated regions and production windows. Independent minimums and maximums are not necessarily available together in one board construction. For product-level information, see our rigid-flex PCB manufacturing service page.
Detailed Process Data
Detailed Rigid-Flex Process Data Ω
Review rigid-flex construction, conductor, drilling, mechanical, electrical and reliability capabilities by region and production window. Define the complete stackup and fabrication requirements when submitting a design for engineering review.
Region Construction and Materials
| Parameter | Capability | Application notes |
|---|---|---|
| Total rigid-flex layers | 2–32 layers | Identify the layer map and which layers continue through each flex region. |
| Flexible layers within the stack | 1–12 layers | Flexible copper layers are included in the total layer count. |
| Rigid base material | FR-4; high-Tg 150°C and 170°C options | Select the material grade according to thermal and electrical requirements. |
| Flex base material | Polyimide (PI / Kapton), PET, PEN | Confirm compatibility with the selected adhesive, coverlay and process. See also flexible PCB manufacturing |
| Coverlay | Polyimide coverlay on flexible areas | Define coverlay openings and coverage in the fabrication data. |
| Stiffener materials | FR-4, aluminum, polyimide, stainless steel | Specify material, thickness and location. |
| Finished thickness | 0.06–4.0 mm | Define rigid-region and free-flex-region thicknesses separately. |
| Copper weight | Flex: 1/3–2 oz; rigid heavy copper up to 12 oz | High copper weights apply to rigid-region construction, not automatically to flexible tails. |
| Flex-region minimum trace / space |
0.5 oz: 4 / 4 mil 1 oz: 5 / 5 mil 2 oz: 5 / 7 mil | Use the entry corresponding to the flexible-region copper weight. |
| Through-hole aspect ratio | Up to 10:1 | Applies to the through-hole depth-to-diameter definition, not laser microvias. |
| Blind-via aspect ratio | Up to 0.75:1 | Confirm dielectric depth, opening definition and the selected manufacturing process. |
Flex-region copper limits apply only to flexible sections. Rigid-region conductor and heavy-copper capabilities are listed separately below.
Rigid-Region Conductors and Holes
| Parameter | Mass production | Prototype / extended review | Application notes |
|---|---|---|---|
| Minimum inner-layer clearance | 3 mil | 3 mil | Applies to rigid-region construction. |
| Minimum line width | 3 mil (0.0762 mm) | 3 mil (0.0762 mm) | Rigid-region value; use the flex-region table for flexible sections. |
| Minimum line spacing | 3 mil (0.0762 mm) | 3 mil (0.0762 mm) | Rigid-region value; use the flex-region table for flexible sections. |
| Minimum drill / process-entry size | 0.10 mm | 0.10 mm | Do not confuse drill size with finished-hole diameter. |
| Finished-hole diameter | 0.152 mm | 0.152 mm | Specify the required finished-hole diameter separately from drill size. |
| Minimum plated hole copper | 25 μm | 25 μm | Specify average or local minimum and acceptance class. |
| Minimum blind / buried via | 0.10 mm | 0.10 mm for 1–18 layers | Define layer span, depth and opening diameter; confirm the full via map. |
| PTH diameter tolerance | ±0.076 mm (approximately ±3 mil) | ±0.076 mm (approximately ±3 mil) | Specify finished-hole diameter and drawing acceptance criteria. |
| NPTH diameter tolerance | ±0.05 mm (approximately ±2 mil) | ±0.05 mm (approximately ±2 mil) | Confirm datum and measurement method. |
| Hole position deviation | ±0.05 mm (approximately ±2 mil) | ±0.05 mm (approximately ±2 mil) | Review against board size, layer registration and feature location. |
Rigid-Region Copper, Mask and Marking
| Parameter | Mass production | Prototype / extended review | Application notes |
|---|---|---|---|
| Rigid-region heavy copper | 4 oz (nominal approximately 140 μm) | Up to 12 oz | Review copper weight with line/space and construction requirements. |
| Minimum solder-mask bridge | 0.10 mm (approximately 4 mil) | 0.10 mm (approximately 4 mil) | Confirm pad geometry and mask registration requirements. |
| Solder-mask colors | Green, black, blue, white, yellow, red | Green, black, blue, white, yellow, red | Specify the required color in the fabrication notes. |
| Silkscreen colors | White, yellow, red, black | White, yellow, red, black | Confirm text and line dimensions during drawing review. |
| Peelable mask | Top, bottom or double-sided | Top, bottom or double-sided | Mark the required area and applicable side. |
A 12 oz rigid-region option does not qualify a 12 oz flexible tail. Review copper balance, transition geometry and lamination for the complete board.
Profile and Mechanical Processing
| Parameter | Mass production | Prototype / extended review | Application notes |
|---|---|---|---|
| Outline method | Routing, V-groove, beveling, punching | Routing, V-groove, beveling, punching | V-groove is for rigid areas and must not cut through a flexible interconnect. |
| Outline tolerance | ±0.15 mm (approximately ±6 mil) | ±0.15 mm (approximately ±6 mil) | Specify rigid outlines, flex outlines and transition boundaries. |
Electrical and Reliability Requirements
| Parameter | Mass production | Prototype / extended review | Application notes |
|---|---|---|---|
| Controlled impedance | ±10% | ±7% | Agree signal/reference layers, geometry, coupon and test method. |
| Insulation resistance | 1 × 1012 Ω (normal) | 1 × 1012 Ω (normal) | Confirm temperature, humidity, conditioning and test voltage. |
| Through-hole resistance | Per approved continuity test plan | Per approved continuity test plan | Specify the continuity threshold and unit in the test plan. |
| Thermal shock | 3 × 10 sec at 288°C | 3 × 10 sec at 288°C | Define specimen, conditioning, cycles and acceptance method; this is not an operating-temperature rating. |
| Warp and twist | ≤ 0.7% | ≤ 0.7% | Define the board or panel condition and measurement method. |
| Electric strength | > 1.3 kV/mm | > 1.4 kV/mm | Confirm test method and dielectric construction. |
| Peel strength | 1.4 N/mm | 1.4 N/mm | Confirm laminate, copper, conditioning and test method. |
| Solder-mask hardness | > 6H | > 6H | Specify the hardness test method; this is not an abrasion-life rating. |
| Flammability | 94V-0 material / construction option | 94V-0 material / construction option | Confirm the applicable recognized material, UL file and thickness range. |
| Electrical test voltage | 50–330 V | 50–330 V | This is an electrical-test setting, not a rated operating voltage. |
Electrical, thermal and mechanical test results require defined specimens, conditions and acceptance criteria. These tests do not replace a project-specific flex-life qualification.
Surface Finishes
| Parameter | Available finishes | Application notes |
|---|---|---|
| Surface finish | ENIG, ENEPIG, OSP, immersion silver, immersion tin, electrolytic hard gold / gold fingers. Gold finger edges are covered on our gold fingers PCB page. | Specify finish type and required thickness or applicable specification on the drawing. |
Stack-Up and Construction
Rigid-Flex Stack-Up and Construction Options
A rigid-flex stackup combines rigid and flexible material sections in one interconnected board. Define the layer distribution in each region, the rigid-to-flex transitions and the intended bend conditions so the construction can be reviewed as a complete design.
Separate Total Layers from Flex Layers
State the total conductive-layer count, then identify which conductive layers continue through each flexible section. A board’s total layer count does not mean every layer is present in every region.
Define Materials by Region
Specify the rigid-region laminate and the flexible-region construction separately, including copper, dielectric, coverlay and bonding materials where applicable.
Identify Flex and Reinforced Areas
Mark bend zones, transition boundaries, coverlay openings, stiffeners and any areas that must remain free to flex. State whether each bend is formed during installation or repeated in operation.
Stack-Up Information for Engineering Review
| Design item | What to provide | Why it matters |
|---|---|---|
| Layer map by region | Total layer sequence and the layers present in each rigid and flexible region. | Establishes the local construction and layer transitions across the board. |
| Rigid-region stackup | Laminate material, copper weight, dielectric thickness and finished thickness. | Supports construction review and electrical or mechanical requirements. |
| Flexible-region stackup | Flex material, copper layers and weights, dielectric, coverlay and bonding layers. | Defines the thickness and layer construction of each flex section. |
| Rigid-to-flex transition | Transition boundaries, coverlay or bondply extents, and nearby via or component locations. | Transition details can affect lamination, drilling and local mechanical stress. |
| Bend zones | Bend line, direction, radius, installed shape, and whether flexing is static or dynamic. | Bend type and construction affect the appropriate mechanical review. |
| Stiffeners and support | Material, thickness, outline and location for each stiffener or support area. | Identifies supported areas while distinguishing them from sections intended to flex. |
| HDI and electrical features | Via types and spans, controlled-impedance nets, target values and reference layers. | Allows the via sequence and electrical structures to be reviewed with the full stackup. |
Provide a layer-by-layer stackup and a fabrication drawing that clearly marks rigid regions, flex regions, transition boundaries, bend zones, coverlay openings and stiffeners.
Design for Manufacturability
Rigid-Flex PCB DFM Review Points
Rigid-flex designs combine different materials, layer structures and mechanical requirements. Review bend zones and rigid-to-flex transitions early so fabrication constraints can be considered before the design is released.
Define Static or Dynamic Flexing
State whether the flex section bends once during installation or moves repeatedly in service. Provide the bend line, direction, radius, angle and installed shape. Bend requirements depend on flex thickness, layer construction, materials and expected movement.
Mark the Rigid-to-Flex Transition
Identify where the layer structure changes and show coverlay and bonding-layer extents. Review nearby plated holes, vias, copper features and components against the actual transition geometry rather than treating it as a standard board edge.
Keep Stress-Sensitive Features Away from Bend Zones
Avoid placing vias, plated holes, pads and components in areas that must bend whenever the design allows. If a feature must be near a bend or transition, mark it clearly for engineering review.
Route Flex Conductors for the Bend
Keep routing smooth through bend areas, avoid abrupt corners and sudden trace-width changes, and minimize unnecessary direction changes. For multilayer flex sections, review conductor alignment between adjacent layers.
Specify Copper, Coverlay and Stiffeners
Identify flex-region copper weight and plane areas, coverlay openings and coverage, plus stiffener material, thickness and location. Keep reinforcement compatible with the areas that need to flex.
Submit Complete Design Information
Include the layer stackup, rigid-flex region drawing, bend requirements, drill data, stiffener details, impedance targets and required inspection or test conditions with the fabrication package.
Inspection and Testing
Rigid-Flex PCB Quality Inspection and Testing
Rigid-flex quality verification combines visual, dimensional and electrical checks with additional tests defined by the design and order requirements. Test methods, sampling and acceptance criteria should be specified for each project.
Inspect Features by Region
Check board outline, rigid-flex transitions, coverlay openings, stiffener locations and specified dimensions against the released fabrication data.
Verify Continuity and Isolation
Test the circuit against the approved netlist and electrical-test requirements to identify opens or unintended connections.
Test to Defined Requirements
Controlled impedance, thermal shock, microsection or flex endurance testing can be specified with the test method, conditions and acceptance limits.
Inspection and Test Methods
| Inspection or test | Purpose | Project definition |
|---|---|---|
| Visual inspection | Review visible workmanship and surface condition, including defects identified by the agreed acceptance criteria. | Specify applicable acceptance class, drawing notes and inspection requirements. |
| Dimensional inspection | Verify board outline, hole locations and selected rigid-flex features against drawing dimensions. | Identify critical dimensions, datums and tolerances. |
| AOI of circuit features | Compare inspected circuit patterns with reference fabrication data to identify pattern discrepancies. | Confirm applicable layers, inspection stage and reporting requirements. |
| Continuity and isolation testing | Check for unintended opens and shorts against the approved electrical test data. | Provide the netlist or approved test data and define the test scope. |
| Controlled-impedance testing | Verify specified impedance structures against the target value and tolerance. | Define target, tolerance, coupon design, test method and applicable production window. |
| Microsection analysis | Examine a prepared cross-section for specified internal construction and plating features. | Specify the feature, sample plan, measurement and acceptance criteria. |
| Thermal-shock testing | Evaluate a defined sample under specified rapid temperature exposure. | State the temperature, dwell, cycle count, specimen and acceptance criteria. |
| Flex-endurance testing | Evaluate a flex section under a defined bend profile while monitoring its specified performance. | Define static or dynamic use, bend radius, angle, cycle count, speed and electrical monitoring. |
Specific sampling plans, test conditions, acceptance limits and reports depend on the applicable drawing, order and qualification requirements.
Engineering Review and RFQ
Prepare Your Rigid-Flex PCB RFQ
A clear fabrication package helps the engineering team review the rigid-flex construction, identify missing information and prepare a more accurate quotation. Send the design files and requirements available for your project.
Core Files and Requirements
Fabrication Data
Gerber RS-274X or ODB++ files, with the required copper, coverlay or mask, legend and outline layers.
Drill Data
NC drill files, hole sizes and plating information. State finished-hole requirements separately from drill sizes.
Layer Stackup
Layer order, materials, copper weights, dielectric details, coverlay or solder mask, and finished thickness by region.
Rigid-Flex Region Drawing
Mark rigid and flex regions, transition boundaries, board outline, bend zones and relevant dimensions.
Bend Requirements
Provide bend direction, radius, angle, installed shape, and whether flexing is static or repeated in operation.
Order and Acceptance Requirements
Include quantity, prototype or production stage, surface finish, critical tolerances, impedance and required tests.
Additional Details That Help the Review
Include these items when they apply to your design or purchasing requirements:
- Stiffener material, thickness, outline and placement.
- Impedance targets, tolerance, reference layers and coupon requirements.
- IPC class or customer-specific inspection criteria.
- Array configuration, panelization preference or quantity per panel.
- Technical contact and drawing revision for clarification.
Ready to request a quotation? Submit your files and identify the required quantity and target delivery schedule.
Request a Rigid-Flex PCB QuoteRigid-Flex PCB FAQs
Rigid-Flex PCB Capability FAQs
Answers to common questions about layer count, regional process limits, impedance and the information needed for a rigid-flex PCB engineering review.
How is the total layer count defined for a rigid-flex PCB?
The total layer count describes the board’s complete conductive layer stack. Flexible copper layers are included in that total; they are not added on top of the total layer count. The layer map should show which layers continue through each flexible region.
PCBELEC’s listed capability is 2–32 total layers, including 1–12 flexible layers within the stack. The actual layer distribution depends on the construction.
Can I use rigid-region line and spacing limits in the flex region?
No. Rigid and flexible regions have separate conductor capabilities. For the flex region, the listed minimum line/space values are 4/4 mil at 0.5 oz copper, 5/5 mil at 1 oz, and 5/7 mil at 2 oz. The rigid-region minimum line width and spacing are listed separately as 3 mil.
What controlled-impedance tolerance can you support?
The listed impedance tolerance is ±10% for mass production and ±7% for prototype or extended review. Define the target impedance, signal and reference layers, stackup, coupon requirements and test method in the design package.
What is the difference between a rigid-flex PCB and a flex PCB with stiffeners?
A rigid-flex PCB integrates rigid and flexible circuit sections into one interconnected board construction. A flex PCB with stiffeners remains a flexible circuit; stiffeners add local mechanical support but do not create a rigid multilayer circuit section. The right construction depends on the electrical, mechanical and assembly requirements.
What files should I include with a rigid-flex PCB RFQ?
Include Gerber or ODB++ fabrication data, NC drill files, a layer stackup, a drawing that identifies rigid and flex regions, and fabrication notes. Add bend requirements, stiffener details, quantity, surface finish, impedance targets and requested inspection or testing requirements where applicable.
See the RFQ preparation section for the full file checklist.
What does the finished-thickness range mean for a rigid-flex board?
The listed finished-thickness range is 0.06–4.0 mm. Because rigid and free-flex regions can have different constructions, state the required finished thickness for each region rather than treating the entire board as one uniform thickness.
Does a listed capability mean every maximum and minimum can be combined?
No. Individual capability limits apply to their stated region, material, copper weight or production window. A design combining several demanding features should be reviewed as a complete stackup and process sequence.
Start Your Rigid-Flex PCB Project
Ready to Review Your Rigid-Flex Design?
Send your fabrication data, layer stackup and rigid-flex region drawing to request a quotation. Include bend requirements, quantity and any impedance, inspection or testing specifications that apply to your project.
- Gerber or ODB++ fabrication data
- NC drill files and layer stackup
- Rigid-flex region and bend details
Final feasibility and quotation depend on the submitted construction, process requirements and order quantity.