Flex PCB RFQ Data Package: Files Buyers Must Send

A global Tier-1 electronic interconnect supplier once asked us to quote a program at 600,000 units per year, delivered by sea freight to CIF Gdansk. The commercial target was clear, but the quotation stalled because the Gerber and technical release package could not leave the customer's internal system. The problem was not price. It was missing manufacturing data.

That case is common in flex PCB sourcing. Buyers send a 3D enclosure screenshot, a BOM note, or a partial Gerber export and expect a stable price. A flex PCB manufacturer can estimate, but cannot responsibly lock cost, yield, tooling, impedance, bend life, or inspection criteria without the real data package.

A flex PCB RFQ data package is the complete set of fabrication, material, mechanical, electrical, and acceptance files a manufacturer needs before quoting and building a flexible printed circuit. It turns a purchasing request into an engineering-controlled manufacturing plan.

TL;DR

• Send Gerber, drill, stackup, outline, drawing, and impedance files together.
• Define bend zones, stiffeners, coverlay openings, and controlled dimensions before price review.
• Quote delays often come from missing stackup thickness, copper type, or tolerance notes.
• IPC-2223 and IPC-6013 references help align design intent and acceptance criteria.
• A complete RFQ package reduces DFM loops, tooling revisions, and first-article surprises.

Why Flex PCB RFQs Need More Than Gerbers

A rigid board can often be priced from Gerber, drill, thickness, copper weight, finish, quantity, and lead time. A flex PCB needs more context because the material is part of the mechanical design. The same copper pattern can behave very differently if the circuit uses adhesiveless polyimide, adhesive-based laminate, RA copper, ED copper, stainless stiffeners, FR4 stiffeners, or pressure-sensitive adhesive.

Flex PCB is a flexible printed circuit that uses thin dielectric films, usually polyimide, to route copper through areas that must bend, fold, or fit into tight mechanical spaces. Polyimide is a high-temperature polymer used because it keeps dimensional stability through lamination and soldering. Rigid-flex PCB is a hybrid board that integrates rigid sections and flexible sections in one laminated structure.

When a manufacturer lacks the stackup and drawing, every quote contains hidden assumptions. Those assumptions become expensive when tooling starts. A 0.10 mm dynamic flex tail and a 0.25 mm static folded flex may look similar in a 2D copper file, but they are not the same product.

For broader design context, review our complete guide to flexible printed circuits, flex PCB materials guide, and flex PCB manufacturing process guide.

"A flex PCB quote is only as accurate as the constraint set behind it. If the file package does not name copper type, total thickness, bend area, and tolerance class, the supplier is pricing an assumption, not your product."

— Hommer Zhao, Engineering Director at FlexiPCB

The Minimum File Set for a Serious Flex PCB RFQ

The fastest RFQs usually arrive as a controlled package, not scattered emails. The package does not need to be fancy, but it must be complete enough for engineering review.

If you can send only one archive, include PDF drawings alongside the CAD outputs. CAM engineers read Gerber data, but they also need human-readable intent. Mark critical dimensions, controlled bend areas, and do-not-change zones clearly.

Gerber, ODB++, and Drill Data

Gerber X2 remains common and is acceptable when exported cleanly. ODB++ can reduce ambiguity because it carries more structured layer information, but many buyers still send Gerber for supplier compatibility. Either format can work if the archive is complete.

For flex circuits, the coverlay layer deserves special attention. Coverlay is not the same as solder mask. It is a polyimide film plus adhesive that protects copper while preserving flexibility. If coverlay openings are exported as a generic solder mask layer, CAM may miss important clearance and fillet expectations around pads.

Drill data should include plated holes, non-plated holes, slots, tooling holes, and any laser microvias. Units must match the drawing. If a slot exists only as a mechanical note, it can be missed during automated import. That creates delay at best and a wrong quotation at worst.

The IPC electronics overview is a useful public starting point for understanding why fabrication data, design standards, and acceptance standards must be aligned. For material behavior, the public article on polyimide explains why this polymer is so common in flexible circuits.

Stackup Data: The File That Changes the Price Most

The stackup is often the missing file that blocks a real quotation. A flex stackup should identify every layer in order, including copper thickness, dielectric thickness, adhesive thickness, coverlay thickness, stiffener, PSA, shielding film, and final target thickness.

A usable stackup note might say:

• 2-layer flex circuit, 0.15 mm nominal total thickness in free bend area
• 18 um RA copper both sides
• 25 um polyimide core
• 25 um polyimide coverlay with 25 um adhesive each side
• ENIG finish on exposed pads
• FR4 stiffener 0.30 mm under ZIF contact area
• No stiffener in active bend zone

Those details determine laminate availability, lamination cycles, dimensional stability, bend radius, and panel yield. The wrong copper type alone can change both cost and fatigue performance. Our adhesiveless vs adhesive-based flex PCB guide explains how that choice affects thickness and reliability.

"When the stackup is missing, I ask the buyer whether the flex is static or dynamic before I ask about price. A 20,000-cycle hinge and a one-time installation fold should not be quoted from the same material assumption."

— Hommer Zhao, Engineering Director at FlexiPCB

Mechanical Drawing: Where Flex Intent Becomes Manufacturable

The fabrication drawing should not repeat every Gerber feature. It should document the intent that CAD layers alone cannot express.

Include these drawing notes:

• Overall outline tolerance, such as +/-0.10 mm or tighter only where needed
• Critical-to-function dimensions, marked separately from reference dimensions
• Bend radius, bend angle, bend direction, and whether bending is static or dynamic
• Stiffener material, thickness, adhesive type, and placement tolerance
• ZIF finger thickness target, exposed copper length, and bevel requirement if any
• Surface finish, solderability requirement, and shelf-life expectation
• IPC standard references such as IPC-2223 for design and IPC-6013 for flex qualification

IPC-2223 is commonly used for flexible printed board design guidance, while IPC-6013 is commonly referenced for qualification and performance of flexible and rigid-flex printed boards. Because the official standards are paid documents, public summaries should not replace the actual customer specification, but naming the standards helps align terminology between buyer and supplier.

Dimensional tolerances deserve restraint. If every outline dimension is +/-0.05 mm, tooling and inspection cost rise quickly. Mark only the features that truly control fit: connector insertion area, camera module alignment, screw slot, sensor window, adhesive datum, or fold stop.

Bend Zones, Transition Zones, and Stiffeners

Flex failures often start where the drawing is silent. A good RFQ package shows where the circuit will bend and where it must stay flat.

Use a simple mechanical overlay if needed. Color the active bend zone, static fold zone, rigid support area, connector contact area, and adhesive attachment area. Add radius and cycle expectations. A supplier can then judge whether the bend crosses vias, planes, pads, stiffener edges, or thick copper.

For bend rules, read our flex PCB bend radius guide, rigid-flex transition zone guide, and flex PCB stiffener guide. These are the places where RFQ assumptions often become field failures.

A stiffener is a local reinforcement bonded to a flex circuit to support connectors, components, contacts, or assembly handling. Stiffeners improve local flatness, but they also create transition edges. If a flex bends at that edge, copper strain concentrates there.

Controlled Impedance and High-Speed Notes

Do not hide impedance requirements in a schematic comment. Put them in the RFQ package as a table.

Controlled impedance on flex depends strongly on dielectric thickness, copper thickness, coverlay, shielding, and bend location. If you need tight impedance, allow the manufacturer to adjust trace width during DFM with approval. Our flex PCB impedance control guide covers this in detail.

Test and Acceptance Requirements

A quotation should define how quality will be proven. At minimum, most production flex circuits need 100% electrical test and visual inspection. Depending on risk, add impedance coupons, cross-section analysis, peel strength checks, solderability checks, dimensional sampling, ionic contamination testing, or bend testing.

Do not ask for every possible test by default. Match inspection to failure risk. A low-cost static FPC in a disposable accessory does not need the same qualification plan as a medical wearable, EV battery BMS flex, or 5G antenna flex.

Useful acceptance notes include:

• Electrical test: 100% netlist test, no opens or shorts
• Dimensional inspection: sample plan and critical dimensions
• Surface finish: ENIG thickness range if required by assembly process
• Appearance: coverlay registration and exposed copper limits
• Reliability: bend test radius, cycle count, and pass/fail resistance change
• Documentation: material certificates, test report, COC, microsection if required

The ISO 9000 overview gives a public explanation of quality-management system language often used in supplier audits. Use it as background, then specify the actual inspection records you need for your product.

"The best RFQ packages separate must-have requirements from preferences. If impedance is critical, mark it. If one outline edge controls connector fit, mark it. If a dimension is only reference, do not force the supplier to inspect it like a safety feature."

— Hommer Zhao, Engineering Director at FlexiPCB

Buyer Checklist Before Sending the RFQ

Before releasing the package, check these items:

• The slug, revision, and file date match across Gerber, drawing, BOM, and notes.
• The stackup names copper type, copper thickness, dielectric, coverlay, adhesive, finish, and total thickness.
• Bend zones and stiffener edges are dimensioned from clear datums.
• Surface finish is chosen for the assembly process, not copied from an old rigid PCB.
• Controlled impedance tables include target, tolerance, layer, and reference plane.
• Quantity is split into prototype, pilot, and annual demand.
• The supplier is allowed to propose DFM changes, but changes require written approval.

For quoting workflow, our how to order custom flex PCB guide and flex PCB cost guide show how data quality affects lead time and pricing.

Frequently Asked Questions

What files are required for a flex PCB quote?

Send Gerber X2 or ODB++, drill files, fabrication drawing, stackup, bend and stiffener notes, surface finish, quantity, lead time, and test requirements. For controlled impedance designs, include target ohms, tolerance, layer, reference plane, and coupon requirement.

Can a supplier quote flex PCB from Gerber files only?

A supplier can give a rough estimate, but the price may change after stackup and mechanical review. Missing details such as 18 um RA copper, 0.30 mm FR4 stiffener, ENIG finish, or +/-0.10 mm outline tolerance can materially change cost and yield.

Should the RFQ include IPC-2223 and IPC-6013?

Yes, if those standards are part of your design and acceptance basis. IPC-2223 is commonly referenced for flexible printed board design, while IPC-6013 is commonly used for flexible and rigid-flex board qualification. Always state any customer-specific requirement as well.

What bend information should I send?

Send bend radius, bend angle, bend direction, static or dynamic use, estimated cycle count, and nearby stiffener edges. For dynamic flex above 10,000 cycles, also identify copper type and keep vias out of the active bend zone.

Why does the supplier ask for annual volume?

Annual volume affects tooling, panelization, material purchasing, test fixture strategy, and unit price. A 10-piece prototype and a 600,000-unit annual program should not use the same cost model or delivery plan.

What tolerance should I use for flex PCB outline dimensions?

Use the loosest tolerance that still fits the product. Many flex outlines can start around +/-0.10 mm, while connector or sensor alignment features may need tighter control. Mark critical dimensions instead of applying tight tolerance everywhere.

How do I avoid RFQ delays?

Send one revision-controlled archive with all manufacturing files, drawings, stackup, quantities, and acceptance notes. Name the critical items clearly and let the manufacturer return DFM questions in one list before tooling release.

Final Recommendation

A complete flex PCB RFQ package saves more time than a fast email. Package the Gerber or ODB++ data with drill files, stackup, fabrication drawing, bend-zone notes, stiffener details, test requirements, and realistic volume splits. The supplier can then quote the product you actually intend to build.

If you are preparing a new flex circuit for prototype or production, contact FlexiPCB or request a quote. We can review your RFQ package, identify missing manufacturing data, and return a cleaner DFM path before tooling starts.