PCB Design Input Checklist: What to Send Before Layout Starts

Before PCB layout starts, send the schematic, verified BOM, component data, board outline, and the constraints that control placement and routing. A revision also needs the last approved design package and a clear change list. The goal is not to collect every file that exists. The goal is to show what is fixed, what is still open, and who can approve each remaining decision.

Match the File Set to the Work Being Requested

Start by naming the task. A new layout from an approved schematic, a board revision, a CAD conversion, and an early design review do not need the same inputs. An unclear request can make an old production file look current. It can also make an unfinished schematic look released.

State the current project stage in a short cover note. Identify the controlling revision, the requested work, the expected output, and the person who can answer technical questions. Mark documents as approved, reference only, or still under review. This status is more useful than a folder full of files with similar names.

When several teams supply data, include a simple file index. It can list the file name, revision, purpose, and approval state. The layout team should not have to compare timestamps and guess which schematic, mechanical model, or component library controls the job.

For a New Layout, Send Design Intent and Physical Limits

The schematic defines connectivity, but it does not fully describe the physical board. Layout decisions also depend on real packages, connector orientation, enclosure limits, signal rules, power paths, and manufacturing needs. The input package should connect those requirements to the circuit.

Input	Required information	Decision it supports
Schematic	Net names, values, interfaces, power rails, and design notes	Electrical connectivity and circuit intent
BOM and component data	Manufacturer part numbers, packages, quantities, datasheets, and approved alternatives	Symbols, footprints, orientation, and part availability review
Mechanical data	Board outline, holes, cutouts, keep-outs, connector positions, and height limits	Fit, access, and fixed placement
Design constraints	Stack-up assumptions, impedance needs, signal rules, current paths, thermal limits, and test access	Placement, routing, and review priorities

Send the native schematic when the designer may need to run checks or update the design. Add a PDF as a stable review copy. If both are supplied, identify which revision controls the work. A PDF that does not match the source file creates uncertainty instead of providing confirmation.

Check the BOM beyond reference designators and values. A generic resistor value does not identify its case size. A connector part number can define pin numbering, mating direction, mounting height, and edge position. Those details affect footprints and placement.

Mechanical information may arrive as a dimensioned drawing, DXF, STEP model, or another agreed format. Whatever the format, it should show the geometry that cannot move. Mark critical dimensions directly. Do not expect the designer to infer them from a product image or an unmarked enclosure model.

If approved footprint libraries exist, identify the parts that must use them. If the designer must create a footprint, agree who will check pin numbering, polarity, pad geometry, and the final library item. A correct schematic symbol paired with the wrong footprint can still produce an unusable board.

Product variants need their own note. Identify the population option that controls the layout and mark parts that may be fitted only on certain versions. Shared footprints, optional connectors, and alternate power sections can change placement space even when one BOM marks those parts as not fitted.

Mechanical files should also use clear units, origin references, and orientation. A correct outline can still be placed incorrectly if the mechanical model and PCB database use different reference points. Confirm the intended top view, connector direction, and enclosure datum before fixed components are placed.

For a Revision, Lock the Baseline Before Listing Changes

A revision starts with one known baseline. Supply the last approved native PCB database when it is available, together with the matching schematic, BOM, fabrication data, assembly data, and drawings. Files from different releases can create false differences and hide the change that actually matters.

Gerber and drill files describe production artwork, but they do not always preserve the editable design rules or component intelligence found in the source database. If manufacturing files are the only available record, say so. The designer can then separate direct checks from items that must be rebuilt or confirmed.

Write each requested change as a controlled instruction. Name the affected circuit, component, connector, dimension, or rule. Explain what must change and what must remain untouched. A marked screenshot can clarify the location, but it should support the change list rather than replace it.

Version the change list with the design package. If a later request replaces an earlier one, record that decision. Otherwise, two valid-looking instructions may send the same area of the board in opposite directions.

Explain the result that the revision must achieve. A note such as “move J3” describes an action but not the acceptance condition. State the required clearance, enclosure fit, access, or circuit change that drives the move. The designer can then check the result instead of following an isolated instruction.

Make Hidden Constraints Explicit

Important PCB layout requirements often sit outside the schematic and BOM. They may be stored in an email thread, a mechanical discussion, or one engineer’s memory. If the layout team cannot see them, the board may be electrically connected and still fail the product requirement.

Stack-up and impedance: Identify controlled-impedance nets, target values, reference layers, and any material or thickness limits. Final geometry depends on the fabrication stack-up.

Power and heat: Mark high-current paths, sensitive supplies, heat sources, copper-area needs, and parts that rely on airflow or mechanical heat transfer.

Placement: Separate fixed locations from preferences. Note connector access, mounting hardware, antenna clearance, display alignment, height limits, and service access.

Signals: List differential pairs, length relationships, clock or RF paths, sensitive analog areas, isolation needs, and return-path concerns.

Assembly and test: State component-side limits, programming needs, test points, probe access, fiducials, depaneling restrictions, and relevant assembly assumptions.

Safety and compliance: Provide the project requirements and required spacing. The designer should not have to guess which standard or product classification applies.

Label every constraint as fixed, preferred, or open. A connector position locked by the enclosure does not have the same status as a preferred capacitor location. When two requirements conflict, identify which one has priority and who can approve the trade-off. That decision should be recorded before the same conflict creates repeated layout revisions.

Agree on the Deliverables Before Work Begins

Define the expected output while the input package is being reviewed. A project can appear complete and still end with a handoff dispute. This happens when editable source files, drawings, or library items were never included in the agreed scope.

The requested package may include native PCB and schematic files. Production outputs may include Gerber or ODB++ data, NC drill files, fabrication drawings, assembly drawings, and pick-and-place data. A released BOM or 3D mechanical exchange file may also be required. Record the agreed list instead of relying on assumption.

Confirm editable-source delivery, file ownership, library handling, naming rules, and revision control. If customer libraries are used, decide whether corrected symbols and footprints return to that library. If new library items are created, define how they will be reviewed and delivered.

At release, the native files, BOM, drawings, and production outputs should refer to the same approved revision. A short release note can list the included files and any open exception. This makes the handoff easier to check without repeating the full design history.

What Can Be Reviewed Before Every File Is Ready?

An early review can begin with incomplete information. Final layout approval cannot. A preliminary package may contain the schematic, an early BOM, a rough board outline, and the main product constraints. That is enough to identify obvious gaps, placement pressure, likely layer-planning questions, and mechanical conflicts.

The review should produce an open-item list. Each item needs an owner and a decision point. Conclusions that depend on final components, enclosure data, stack-up, or compliance requirements must remain conditional until those inputs are confirmed.

Before routing is released, close any open item that can change a footprint, net connection, board outline, layer structure, fixed placement, or electrical rule. If one item must remain open, record the assumption and the person who will approve it.

Final PCB Design Input Check

Name the task: new layout, revision, CAD conversion, or early review.

Identify the controlling schematic and design revision.

Verify BOM part numbers, packages, and approved alternatives.

Include datasheets and package drawings for unusual or critical parts.

Provide the board outline, holes, cutouts, keep-outs, and enclosure limits.

Mark fixed connector, display, antenna, switch, and mounting locations.

List stack-up, impedance, power, thermal, signal, assembly, and test constraints.

For a revision, supply one baseline package and one controlled change list.

Separate fixed requirements, preferences, and unresolved decisions.

Confirm the required final files, editable-source scope, and library handling.

Assign an owner and approver to every open item.

When the file set is complete enough for review, the PCB layout process can begin from an agreed baseline instead of a collection of assumptions.