PCBA Testing and Inspection: AOI, ICT and Functional Test

Start with what the assembled board must do

Whether you are an individual buying prototypes, a small business launching a product or a larger importer placing repeat orders, ask the supplier what each test will verify. A quotation saying only “tested” leaves the method, coverage and evidence undefined.

Separate assembly workmanship, electrical integrity, operating performance and destination-market compliance. Passing one check does not establish all the others. Build the inspection plan around the board design, intended use and consequences of failure.

AOI, X-ray, ICT, flying probe and functional test compared

Use complementary methods where the risks justify them. Ask for a coverage statement identifying what can be inspected or tested, what cannot, and how the remaining risks will be addressed.

NASA technical material illustrates the distinction between visible-feature inspection and examination of hidden features. These specialist examples explain inspection limits; they are not purchasing requirements for ordinary commercial orders. IPC-hosted technical material explains ICT coverage, while HIOKI documents flying-probe equipment for populated boards.

Who writes and approves the test procedure?

As a purchasing arrangement, give the product designer or another competent engineer responsibility for defining required performance and pass/fail limits. Ask the factory’s test engineer to develop the production test procedure, test software and fixture around those requirements, then obtain buyer approval before production.

If the factory also designed the product, require it to submit the procedure for approval. If you do not have an engineer, commission that work explicitly rather than expecting an inspector to invent operating limits.

Require the procedure to identify the board revision, firmware, equipment, connections, safe power-up sequence, test conditions, measurements, limits and treatment of failures. Agree how the test setup will be validated, including suitable known-good and known-fault examples where practical.

Freeze approved revisions and require written approval for changes. For the underlying manufacturing information, use the Gerber, BOM and CPL file guide.

Specify IPC-A-610 by name, revision and class

IPC-A-610 is titled Acceptability of Electronic Assemblies. It provides assembly acceptance criteria; citing it does not define a complete functional test or establish market authorisation. IPC J-STD-001 is the separate standard titled Requirements for Soldered Electrical and Electronic Assemblies.

The public IPC-A-610E extract distinguishes the service requirements summarised below. These are historical definitions, not a substitute for checking the edition you intend to use. Select the class with the product engineer and name the agreed revision in the purchase order. Use that edition’s detailed criteria to resolve actual defects.

Write down any customer-specific requirements and the order of precedence if documents conflict. Avoid vague phrases such as “IPC quality” or choosing a class solely because it sounds more demanding.

What to put in the purchase order

Identify the assembly, approved manufacturing-file revisions, BOM, permitted substitutions, firmware and approved test-procedure revision. State the IPC-A-610 revision and class, plus customer-specific acceptance requirements.

List each inspection and test separately. For each, specify whether every board or a sample is checked, which features or functions are covered, the acceptance limits and when the check takes place. State whether testing must be repeated after repair, reprogramming or other changes.

Require a shipment-specific report identifying the order, lot, board revision, procedure revision, quantities inspected, quantities passed and failed, defect findings and disposition. For measured tests, require results against limits and traceability to the relevant board or serial number.

Specify supporting evidence: labelled defect photographs, agreed X-ray images, test logs, equipment identification and calibration status where relevant. Agree the report format, delivery deadline, record-retention period and who authorises shipment.

Define failure handling before production: segregation, investigation, repair approval, retesting, replacement, responsibility for costs and release of a rejected lot. Require original failures to remain visible in the records after a successful retest.

Separate procedure development, fixtures, programming, production testing, reports and any external laboratory work in the quotation. See the PCBA quote structure guide for the wider cost breakdown.

Sampling: distinguish lot acceptance from testing each board

ISO 2859-1:2026 covers acceptance sampling by attributes using schemes indexed by acceptance quality limit, or AQL, for lot-by-lot inspection. It supports lot-acceptance decisions; it does not establish that every uninspected board works.

For sampled checks, agree the standard and edition, lot definition, random selection, inspection level, defect categories, AQLs, sample sizes, acceptance/rejection numbers and applicable switching rules. Do not insert a familiar AQL value without considering the product’s failure risks.

Keep the sampling decision separate for each method. A sampled pre-shipment workmanship inspection can accompany electrical or functional tests on every board. Conversely, saying every board is tested still leaves the coverage of that test to be defined.

Ask the engineer to identify checks that should cover every board and whether sampling is appropriate for the remaining checks. For prototypes and isolated orders, obtain a plan suited to that situation rather than borrowing a repeat-production sampling scheme without review.

If you sell in the US or EU

US customs — guidance checked 18 October 2026: CBP explains that owners or purchasers may file entry documents themselves or engage a licensed customs broker. The importer of record remains responsible for accurate entry documentation and applicable duties, taxes and fees when using a broker. Prepare the assembly description and import documentation separately from its quality-test report.

US tariffs — guidance checked 18 October 2026: USTR provides an HTS-based search for China Section 301 actions and additional duties, with separate exclusion information. Check the actual classification and applicable exclusions before shipment; this guide gives no single PCBA tariff rate.

US medical applications — guidance checked 18 October 2026: FDA directs businesses to define intended use and indications for use when determining whether a product meets the medical-device definition. For a medical application, establish the product’s regulatory status and required evidence separately; an IPC acceptance result does not settle that question.

EU — guidance checked 18 October 2026: CE marking is required only for products covered by EU rules that specifically mandate it. A business having a product made and selling it under its own name or brand is treated as its manufacturer and is responsible for the complete product’s compliance, including supplied components. Determine the applicable conformity assessment and technical documentation; AOI, ICT and functional-test reports alone do not establish conformity.

A short UK example: keep testing costs and import valuation clear

HMRC guidance checked 18 October 2026 states that import VAT valuation includes customs value, relevant incidental expenses and duties or other charges payable on importation, excluding VAT itself. Incidental expenses include packing, transport and insurance to the goods’ first UK destination. For a shipment to Cambridge, give the customs agent the goods invoice and separate fixture or testing charges, and ask how each should be treated for valuation.

Checking the factory’s testing capability

Before relying on a supplier’s equipment list, ask it to demonstrate the proposed procedure on the relevant assembly and provide a specimen report. Check who owns the test software and fixture, who can maintain them, and whether any work will be subcontracted.

Ask whether Cambridge China Bridge’s factory verification service can cover these capability questions. Its published service terms say audits and inspections are usually included in the quote for an order placed with it; complex checks needing a third party cost extra by prior agreement. Confirm the specific scope and charges in your quotation.

Sources

The official publisher, government, NASA and equipment-manufacturer sources below support the standards, inspection principles and market-specific facts. Purchase-order requirements are recommended buying practices. IPC’s public historical extract supports the class summaries; the contract should identify the edition actually agreed. The IPC Electrical Test Conditions paper concerns bare-board testing and should not be used as evidence of assembled-board coverage. Cambridge China Bridge’s own service page supports the description of its commercial terms.