PCB vs PCBA: Differences, Files, Cost and Ordering Scope

Treat the quote as a list of deliverables, not just a product name. The table separates typical responsibilities; your purchase order should resolve exceptions.

Fabrication produces a board to the approved layer and mechanical data. Assembly uses its lands and holes to connect components. Finish, panel rails, fiducials, tooling holes and depanelization therefore need to support the assembly process before the bare board is released.

A fabrication change can affect assembly: a finish substitution may change soldering conditions, a panel revision can move tooling locations, and a board revision can invalidate a stencil. Compare the manufacturing process with the assembly process and keep both under the same revision-control plan.

With turnkey assembly, the supplier sources agreed components and usually coordinates bare-board fabrication as part of the scope. With consigned assembly, the customer provides some or all material. Partial-turnkey divides responsibility by BOM line. None of these terms removes the need for an approved substitution policy.

For consigned parts, state quantities, spare allowance, packaging, moisture sensitivity and responsibility for unusable material. For turnkey sourcing, provide manufacturer part numbers, approved alternates and any traceability restrictions. A generic value such as “10 kΩ resistor” is not enough to approve package, tolerance, power rating and qualification.

Bare-board electrical test checks connectivity and isolation against the agreed net data; it does not exercise firmware or component function. AOI examines visible assembly features; X-ray can reveal hidden solder-joint geometry, subject to equipment and inspection criteria. Neither substitutes for a functional test plan.

If you need programmed and tested assemblies, provide firmware, programming access, fixture responsibilities, power limits, test steps and pass/fail criteria. Identify whether the supplier should report every unit or a sample. Do not assume “tested PCBA” includes all of these operations.

State the desired output, quantity and revision first. Attach fabrication data for bare boards; add BOM, centroid, assembly drawing, DNP list, polarity notes and test instructions for PCBA. List stencil, fixtures, programming, inspection reports, packaging and shipping as separate scope items where relevant.

Compare quotations against the same sourcing responsibility and acceptance requirements. A low assembly line item that excludes expensive components or functional testing is not comparable to a complete turnkey quote. Use the Gerber, BOM and pick-and-place checklist before sending an RFQ.