FlexiPCB founded its flex circuit operation in 2007 and now runs 7 manufacturing facilities with ISO 9001:2015, ISO 13485, and IATF 16949 quality systems. This FR-4 PCB page is scoped to what the factory can evidence: FR-4 rigid sections inside rigid-flex builds, FR-4 stiffeners under connectors and SMT zones, and procurement programs where the buyer needs one DFM response for Gerber, BOM, stackup, drawing, and inspection records. A typical Tier-1 RFQ we see is 200 engineering samples followed by a 2,000-10,000 piece pilot, with quotation blocked by Tg selection, ZIF thickness, bend relief, and Class 2 versus Class 3 inspection requirements.
FR-4 carries connectors, ICs, and mechanical fasteners while polyimide routes through the moving or folded area. Procurement gets one quote instead of splitting rigid board, flex tail, and assembly risk.
FR-4 islands support sensors, battery contacts, and charging pads while flex sections handle packaging. ISO 13485 expectations and IPC inspection notes are reviewed before the sample build.
FR-4 sections can stabilize CAN, sensor, or power interfaces while flex geometry absorbs vibration and enclosure constraints. IATF 16949 review helps buyers align PPAP-style documentation requests early.
FR-4 stiffeners are specified where a 0.1-0.2mm flex tail cannot meet insertion thickness, coplanarity, or pull handling requirements during production assembly.
Upload Gerber or ODB++, stackup, mechanical drawing, BOM, quantity, target lead time, and any IPC-A-610 or IPC-6013 acceptance level required by the end customer.
Our CAM team checks FR-4 thickness, bend-to-rigid transition, drill limits, impedance notes, coverlay openings, and connector stiffener dimensions before commercial pricing.
You receive a quote with sample lead time, production lead time, tooling assumptions, test method, and any design issue that could affect yield or sample approval.
Samples are built with production-intent materials. AOI, electrical testing, visual inspection, and requested report formats are aligned to the RFQ package.
For 2,000-10,000 piece pilots, the same drawing revision, stackup, test records, and material notes carry forward so procurement does not restart qualification.
The release file locks revision, approved deviations, packaging, labels, certificates, and shipment plan before repeat production begins.
We quote FR-4 where it supports flex, rigid-flex, stiffeners, or assembly programs. Pure commodity FR-4 panels with no flex requirement are better handled by a high-volume rigid board shop.
The RFQ is checked against published limits: 10mm×15mm to 406mm×736mm rigid-flex panel size, 0.15mm mechanical drill, and ±0.1mm outline tolerance.
IPC, UL, and IATF 16949 are used as procurement filters, not decorative badges. They drive inspection level, material traceability, report format, and release documents.
The same engineering notes used for samples are retained for pilot and production, reducing repeated clarification between buyer, PCB engineer, and assembly team.
Complete inputs let engineering quote without hiding risk in assumptions.
Gerber or ODB++ files plus mechanical drawing and revision level
Stackup showing FR-4 thickness, polyimide sections, copper weight, and Tg requirement
BOM, connector drawings, ZIF insertion thickness, and assembly notes
Sample quantity, annual forecast, target MOQ, and required sample lead time
Inspection needs: IPC class, electrical test report, impedance report, or certificate package
The response is structured for procurement comparison and engineering signoff.
DFM notes on FR-4 thickness, bend transition, stiffeners, drills, and manufacturability
Sample and production pricing with tooling, MOQ, and lead-time options separated
Recommended inspection plan tied to IPC, UL, ISO 9001:2015, ISO 13485, or IATF 16949 needs
Material and stackup comments for Tg, FR-4 grade, polyimide material, and surface finish
Risk list for items that need buyer confirmation before sample release
No. This FR-4 PCB service is for rigid-flex and flex-related programs where FR-4 interacts with polyimide, stiffeners, connectors, or assembly. FlexiPCB can review FR-4 rigid sections from 0.2-4.0mm rigid-flex builds, but a simple commodity two-layer rigid panel with no flex requirement is outside the best-fit scope.
Send Gerber or ODB++, stackup, mechanical drawing, BOM, connector drawings, quantity, target lead time, and the required IPC class. If the design includes ZIF fingers or SMT on flex, include stiffener thickness and placement notes so engineering can check ±0.1mm outline tolerance and insertion thickness before pricing.
Yes, if the sample package uses production-intent materials, frozen revision control, and the same inspection plan. FlexiPCB commonly reviews sample quantities around 200 pieces with pilot forecasts of 2,000-10,000 pieces, then carries the stackup, test report, and accepted deviations into repeat production.
IPC requirements define workmanship and acceptance expectations, while IATF 16949 affects automotive documentation discipline. For an automotive RFQ, we confirm inspection level, material traceability, change control, and report format before samples so the buyer is not surprised during pilot approval.
Choose FR-4 stiffener when a connector, ZIF tail, screw area, or SMT island needs rigidity that 0.1-0.2mm polyimide cannot provide. Polyimide stiffeners fit tight bends and thermal match better, but FR-4 gives a board-like interface for insertion thickness and handling.
Lead time depends on layer count, FR-4 thickness, coverlay openings, surface finish, and test reports. Simple flex prototypes can be quoted with 24-72 hour options elsewhere on the site; FR-4 rigid-flex or stiffener programs should be quoted from the actual package so tooling, material, and inspection time are visible.
These public references explain the procurement language behind inspection, safety, and automotive quality requests.
IPC is referenced during RFQ review when acceptance level, traceability, or automotive documentation affects release risk.
IATF 16949 is referenced during RFQ review when acceptance level, traceability, or automotive documentation affects release risk.
UL is referenced during RFQ review when acceptance level, traceability, or automotive documentation affects release risk.
The page is written from the supplier side: what engineering checks before a quote is safe to use.
Founder and Technical Reviewer, FlexiPCB
Hommer Zhao reviews flex and rigid-flex RFQs with the factory engineering team. For FR-4 PCB programs, his first check is whether the rigid section, stiffener, connector, and bend area can be approved as one controlled release instead of four separate supplier assumptions.
Founded
2007 flex PCB manufacturing operation
Factory footprint
7 facilities and 15,000 sqm factory space
Quality systems
ISO 9001:2015, ISO 13485, IATF 16949
Measured limits
0.15mm drill, ±0.1mm outline, 0.2-4.0mm rigid-flex thickness
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