PCB MANUFACTURER IN CHINA
Multilayer PCB Manufacturer in China: Stack-Ups & Specs
Specify a multilayer PCB in China with an agreed stack-up, material construction, copper requirements and inspection scope before releasing fabrication files.
A multilayer PCB combines multiple copper layers separated by insulating material. Layer count describes only part of the build: the order of signal and reference layers, dielectric spacing and finished dimensions also need agreement. This page helps engineers and buyers turn those requirements into a quotation that can be reviewed against the same specification.
Use our PCB manufacturing overview for the wider service scope and the capabilities reference for an initial discussion. Availability, tolerances, material combinations and delivery dates require confirmation for your design. Send the released package when requesting a project-specific quote.
Key specifications to agree with the manufacturer
A useful multilayer specification separates design requirements from proposed manufacturing details. State the values that the finished board must meet, identify acceptable alternatives, and ask the fabricator to return a controlled stack-up for approval. The checklist below is a request template, not an unconditional capability or tolerance table.
| Requirement | Include in your request | Obtain confirmation |
|---|---|---|
| Layer structure | Copper layer count, order and signal/plane functions | Numbered build drawing matching the fabrication outputs |
| Dielectric construction | Required spacing or electrical constraints; material restrictions | Proposed cores, prepregs and finished dielectric dimensions |
| Board and copper thickness | Finished board target and tolerance; copper requirement by layer | Measurement basis and distinction between starting and finished copper |
| Impedance | Target, tolerance, signal type, layer and reference plane | Proposed geometry, permitted changes and agreed verification method |
| Holes and vias | Finished hole sizes, layer spans and any filling or capping | Feasible via construction and any process-related exceptions |
| Finish and acceptance | Surface finish, mask, dimensional priorities and required records | Inspection scope, supplied evidence and exception-approval process |
Choose layers by routing and reference needs
Start with placement, routing access, power distribution and the signals that need controlled return paths. Ask your designer to explain what each additional layer accomplishes. A layer count selected only to match a competitor’s product does not establish that your own interfaces, connector arrangement or mechanical envelope can be implemented successfully.
Texas Instruments’ TUSB73x0 layout guide explains the value of nearby solid reference planes and warns against routing across breaks in the relevant plane. Use the guidance for the actual devices in your design when assigning layers and reviewing return paths. TI’s layout guide, sections 4.2 and 4.3.
- Controller or interface board: review connector escape, power routing and reference continuity before deciding whether the proposed layer count is sufficient.
- Dense digital design: review package breakout and signal transitions together with the stack-up; identify any required special via structures.
- Measurement or mixed-signal design: document sensitive signal paths, power requirements and the device-specific grounding guidance the layout must follow.
These are planning contexts, not evidence that a particular layer count suits every product in those categories. Keep the electrical review and the manufacturing feasibility review connected throughout the design.
What a stack-up drawing needs to show
The stack-up is an ordered construction document. Give each copper layer an unambiguous identifier and show the insulating sections between them. Include the relevant dimensions, material identifiers and revision. A label such as “six-layer FR-4” leaves too much unspecified for a controlled build or an informed comparison between quotations.
In a conventional multilayer lay-up, cores, prepreg and copper foil form the construction; heat and pressure bond the layers. Eurocircuits illustrates one such process in its lay-up and bonding explanation. Treat it as a process example, not a description of an unverified facility used for your order.
Illustrative layer-order discussion
The following four-layer arrangement is a conversation starter for a design with signals and power routed on the outer layers. It deliberately omits material and thickness values. It is not a validated stack-up, a promised manufacturing option or a substitute for checking power delivery, signal integrity and routing feasibility.
| Layer | Proposed role | Review question |
|---|---|---|
| L1 | Top components, signals and power routing | Do critical routes retain their intended reference? |
| L2 | Ground reference | Are required return paths continuous beneath L1? |
| L3 | Ground reference | Are required return paths continuous beneath L4? |
| L4 | Bottom signals and power routing | Are power routing and layer transitions acceptable? |
The released version must add the dielectric sections, copper and finished thickness requirements, material construction and any impedance details. Ask the fabricator to review the physical build, including copper distribution and symmetry, and return proposed changes for engineering approval.
Specify material beyond the FR-4 label
State whether a named material is mandatory or whether alternatives may be proposed. Identify the electrical, thermal and assembly requirements that matter to the design. An approved substitution should preserve those requirements through an engineering review; similarity in a short product description is not enough to establish equivalence.
For example, Isola’s FR408HR Dk/Df tables list values by construction, resin content and frequency. This shows why a single dielectric number should not be applied indiscriminately across a material family. Ask which construction and modelling values support the proposed build. Isola’s FR408HR construction tables.
If the quoted material changes, record the exact alternative and have the design owner review the consequences before release. Do not treat a laminate supplier’s product certification as proof that a particular PCB factory or finished product holds the same certification.
Make impedance and tolerances reviewable
For each controlled-impedance requirement, identify the net group, target and allowed deviation, routing layer, intended reference and whether it is single-ended or differential. Ask the supplier to identify the proposed trace geometry and verification scope. Obtain approval before changing dimensions that affect the released design.
Similarly, clarify whether a copper requirement refers to starting foil or finished copper, and whether a hole dimension refers to a finished hole. Separate a preferred nominal dimension from an acceptance limit. List mechanically critical features individually rather than assuming one general note resolves every fit requirement.
Illustrative comparison: two offers can have the same six-layer count and overall thickness yet propose different dielectric spacing beside a critical signal layer. Flag that difference for electrical review and confirmation of the trace geometry. Matching the headline dimensions alone is not a basis for declaring the offers technically equivalent.
Review cost, timing and acceptance as one package
Ask each supplier to quote the same revision, construction and required evidence. Identify material availability, special via processing, inspection requirements and unresolved engineering questions in the response. Request a separate explanation of alternatives that could change cost or timing, with their technical consequences clearly stated.
- Confirm the delivered quantity and format, including any assembly-panel requirements.
- Separate fabrication, assembly where required, shipping and receiving milestones.
- Record which approvals must be complete before the quoted manufacturing period begins.
- Agree how changes after release will affect the build, price and delivery estimate.
For acceptance, specify the records you need rather than asking only whether the board will be “tested.” Eurocircuits describes microsectioning as destructive sample examination used to inspect internal structure, layer registration and plating. If such evidence is required, agree the sample or coupon, inspection scope and supplied report in advance. Microsectioning explained.
A sample inspection is not a functional test of every assembled product. Use our quality and evidence checklist to define the acceptance package, and the prototype planning page when the first build is intended to answer a specific design question.
Release checklist for the purchasing handoff
- Match the fabrication archive, drawings and approved stack-up to one board revision.
- Resolve material substitutions, impedance geometry and any manufacturing exceptions.
- Confirm that copper-layer names and drill-layer spans agree across the package.
- Record the required inspections, reports, quantity, format and delivery assumptions.
- Identify who may approve changes and retain the written release decision.
Use the quotation file checklist to assemble the package. If populated boards are required, include the separate assembly scope and associated files. A fabrication quotation alone does not establish that components, assembly or functional testing are included.
Frequently asked questions
Is a higher layer count always better?
No. Choose layers to meet the routing, reference-plane, power and mechanical requirements of the actual design. Ask what each extra layer contributes and compare feasible constructions. Additional layers do not remove the need for electrical review, manufacturability checks or an agreed acceptance specification.
Can I order using only layer count and board thickness?
Those details can start a discussion, but they do not fully define a multilayer build. Provide the fabrication files, material restrictions, copper requirements and relevant electrical or mechanical constraints. Review the supplier’s proposed stack-up and any exceptions before approving the order.
Can the manufacturer choose an equivalent laminate?
Allow proposals only if your requirements permit them. Ask for the exact material and construction, then have the design owner review the electrical, thermal and assembly implications. Record the approval in the released documentation. A generic FR-4 label does not demonstrate equivalence for every application.
Does controlled impedance include a measurement report?
Confirm that explicitly in the quotation. State the target, tolerance and relevant structures, then agree the verification method, sampling basis and documentation. Do not assume that a routing calculation, an electrical connectivity check and a supplied impedance measurement report are interchangeable deliverables.
What determines the multilayer PCB delivery date?
The accepted design, material availability, construction, required inspections and outstanding approvals all need review. Request a written estimate tied to a defined release condition. Account separately for assembly and shipping if required; this page does not promise a fixed turnaround for every multilayer design.
Request a multilayer PCB quotation
Send the board revision, proposed stack-up, fabrication package, required quantity and delivery window. Highlight non-negotiable requirements and list acceptable alternatives separately so the quotation can be checked against the same technical scope.