A useful PCB assembly RFQ gives the supplier one released board definition, an identifiable component list, quantity requirements and a clear boundary for inspection and testing. The objective is to make different quotations describe the same build. A low unit price means little if one quotation includes component procurement and functional testing while another excludes both.
Start with a small release manifest rather than sending a folder of exports from several design iterations. If a decision is still open, identify it as an open question. That lets the supplier separate a budgetary estimate from a quotation based on approved manufacturing inputs.
1. Keep every manufacturing file on the same revision
Use the project name, board revision and assembly variant in the RFQ subject and release manifest. Include a release date and the person responsible for approving technical questions. The manifest should identify the fabrication data, BOM, placement data, assembly drawing and test instructions that belong together. File checksums can help distinguish approved exports from similarly named files, but they do not establish that the design itself is correct.
Check consistency at the reference-designator level. A component marked DNP in the BOM should have the same intended status in the assembly drawing and placement output. A connector moved in a layout revision should appear in the placement data generated from that revision. A supplier should not have to choose which of two conflicting files represents your intent.
Fabrication data and board requirements
If the order includes bare-board procurement, supply fabrication outputs together with the board outline, drill information and fabrication requirements. Identify the approved stackup, material requirements, finish and critical tolerances. Where a requirement is not fixed, ask the supplier to propose an option for engineering approval. Do not write “standard PCB” where the electrical or mechanical design depends on a particular construction.
If you are supplying finished bare boards, state that explicitly. Include the board identification and relevant fabrication records, and explain whether the assembly supplier needs to inspect incoming boards or only confirm quantity and condition. The manufacturing file requirements page provides a starting checklist for this handoff.
BOM, placement output and assembly drawing
The BOM should identify each fitted item with its manufacturer and orderable manufacturer part number, quantity per assembly and reference designators. Include variant and DNP information in a format that cannot be mistaken for an approved alternate. A supplier part number can help purchasing, but it should not replace the manufacturer’s identity.
Confirm the placement format with the assembler. For example, the KiCad 8.0 placement export documentation describes position and orientation data, selectable units and origins, and options affecting excluded or DNP footprints. Record the settings used and check them against the intended assembly. Do not assume another CAD tool or software version uses the same conventions. For a worked review, see how to check placement-file origins, units and rotation.
The assembly drawing should carry information that cannot be inferred reliably from a footprint: connector orientation, polarity, mechanical placement, fitted options and special assembly notes. Resolve document precedence before release. A statement that the drawing takes precedence does not make a contradictory BOM safe to use.
2. Define quantity breaks and sourcing responsibility
Request the quantities you actually need to compare. Separate prototype quantity, expected pilot quantity and potential production quantity. A forecast is useful planning context; it is not automatically a purchase authorization. Identify whether you need one delivery or split shipments, and distinguish a preferred delivery date from a fixed project constraint.
State who supplies each category of material: bare boards, components, firmware, fixtures, cables and packaging. For a turnkey PCB assembly scope, ask the quotation to identify procurement assumptions, shortages and proposed alternates. For consigned material, agree how incoming quantity, packaging condition and attrition requirements will be reconciled before the build starts.
Do not authorize unrestricted substitutions with a broad phrase such as “equivalent parts allowed.” A compatible package does not establish electrical, thermal or firmware compatibility. List approved alternates or name the person who must approve proposed changes. If purchasing is urgent, specify which items can be reviewed independently and which block release of the complete kit.
Ask how excess material and nonrecurring items will be handled. Minimum purchase quantities, stencils, fixtures and programming tools may affect the quotation even when the board quantity is small. The important comparison is the complete scope and ownership of those items, not a unit-price column alone.
3. Write down what inspection and testing must demonstrate
“Fully tested” is too ambiguous for an RFQ. Separate assembly inspection, bare-board electrical testing, firmware programming and board-level functional testing. Each addresses a different set of questions. An inspected solder joint does not demonstrate that the application firmware runs correctly; a power-on check does not establish coverage of every interface.
Define the expected evidence for each stage. If programming is included, identify the firmware artifact, approved version, programming interface and confirmation method. For a functional test, provide operating conditions, stimulus, measurement limits and required records. If the test procedure is still being developed, ask for fixture or test-development work as a separate scope item.
Where an assembly standard is required, name the applicable document, agreed revision and acceptance class in the order requirements. IPC distinguishes the soldering process and material requirements addressed by J-STD-001 from the post-assembly acceptance role of IPC-A-610 in its official explanation of the two standards. A reference to that explanation is not a substitute for the applicable standards or a claim that any supplier is certified.
For hidden joints or inaccessible nodes, discuss what can actually be inspected or tested. Ask the supplier to identify coverage limitations rather than attaching an unsupported “100% quality” promise. The inspection and testing scope should be agreed before you compare quotations.
4. Use a worksheet that exposes different assumptions
The following example is an illustrative comparison structure for the same board at 10, 100 and 500 units. It contains no price estimates or claims about supplier capability. Fill it with the supplier’s actual responses and resolve gaps before selecting an order scope.
| Comparison field | What to request | Why the answer matters |
|---|---|---|
| Build identity | Board revision, assembly variant and release manifest | Confirms that each quotation uses the same approved inputs. |
| Quantity breaks | Separate quotations for 10, 100 and 500 assemblies | Shows the stated assumptions at each quantity without treating a forecast as an order. |
| Materials | Included bare boards and parts; exceptions and proposed alternates | Exposes material exclusions and items needing engineering approval. |
| Nonrecurring items | Stencil, setup, fixtures and test development listed separately | Makes the initial build comparable with a repeat order. |
| Inspection and test | Methods, agreed criteria, limitations and delivery records | Prevents different test scopes from hiding behind the same label. |
| Schedule | Material readiness, engineering approvals and production dependencies | Shows what must happen before the quoted lead time can apply. |
| Delivery and leftovers | Packaging, split shipments, excess parts and tooling ownership | Clarifies the handover after the boards are built. |
Consider a simple mismatch: one quotation includes a test fixture and a recorded functional test; another covers assembly inspection only. The second quotation may be cheaper while leaving work with your engineering team. Request a revised common scope before treating that price difference as manufacturing savings.
5. Check the RFQ before sending it
- One board revision and assembly variant appear consistently across the manifest and released exports.
- The fitted BOM, DNP list, placement output and drawing agree.
- Material ownership, approved alternates and substitution authority are explicit.
- Quantity breaks, shipment needs and schedule dependencies are stated.
- Inspection, programming and functional testing have separate requirements and deliverables.
- Open engineering questions are listed with an owner and a release decision.
For an early NPI build, use the RFQ review to identify what must be learned from the first article before releasing the remaining boards. The prototype-to-production guide outlines the broader handoff. Keep the unresolved items visible in the quotation and approval record; silently treating them as finished requirements makes the next build harder to reproduce.