What this section is for
A quality requirement is a sentence that both parties can check. Most quality disputes do not come from a supplier doing bad work; they come from a requirement that was never written down precisely enough to be checked, and which both parties therefore read differently until a shipment was rejected.
This section is about writing requirements that can be checked, and about knowing what each standard does and does not cover.
The distinction that runs through every page here is the one between a certificate and evidence. A certificate says a management system exists and has been audited. It says nothing about the batch in front of you. Evidence is the record that follows a specific order: which material, which revision, which inspection, which measurement, who signed. Buyers who ask for certificates get a system; buyers who ask for evidence get a shipment they can defend.
Four standards, two halves of the product
The most common error in a PCB quality requirement is naming one standard for a product that needs two. A board has a bare half and a populated half, they are governed by different documents, and a purchase order that covers only one of them leaves the other to whatever the supplier does by default.
The pairing is what makes the requirement complete. IPC-6012 and J-STD-001 say how the thing must be built; IPC-A-600 and IPC-A-610 say what an inspector accepts. Naming only the acceptance standard leaves the process open. Naming only the process standard leaves the verdict open.
| Part of the product | Qualification | Visual acceptance | Notes |
|---|---|---|---|
| Bare rigid board | IPC-6012 | IPC-A-600 | Both carry classes; a Class 3 assembly normally needs a Class 3 bare board |
| Soldered assembly | J-STD-001 | IPC-A-610 | One is the process, the other is the judgment on the result |
| Assembly workmanship, additional | — | IPC-A-610 | The document most quoted and least often versioned |
What "class" means, and what it does not
All four documents carry classes, and in all four the class is chosen by the consequence of failure rather than by the customer's preference. The class is not a quality score. It is a statement about how much evidence and how much scrap the programme is willing to pay for.
The full treatment of that argument, including where the cost premium actually goes and why a Class 3 label does not by itself buy reliability, is in the Class 2 versus Class 3 page. It is the page to read first if you are writing a purchase order.
Two points from it are worth carrying into everything else here.
The classes are cumulative. A condition that is a defect at a lower class is a defect at a higher class; the direction only goes one way.
The class must be decided before the design is released. A pad geometry that cannot support the class will produce either rework or a quietly relaxed inspection, and the second outcome is worse because nothing on the paperwork shows it.
Where test and inspection fit
Inspection and test answer different questions, and programmes that treat them as interchangeable end up with neither.
Visual acceptance asks whether a feature meets the criteria for its class. Electrical test asks whether the netlist is intact. Both are per-unit and both are cheap relative to the cost of a failure, which is why they are the default.
Qualification testing asks whether the product will survive its environment, and it is not per-unit: it is a sample, a chamber and a duration. Thermal cycling, vibration, drop, humidity and ionic contamination all live here. A programme that accepts an inspection report in place of a qualification test has bought paperwork for a question it did not ask.
The bare-board side of this is covered in the bare-board testing and inspection page, which distinguishes what a flying probe finds from what an AOI finds and what neither can see. The populated side is in the PCBA testing page. The specific case of flying probe testing at prototype and low volume, where a fixture is not economic, is in the flying probe page.
Test coverage is a design output, not a purchasing option. If the design has no test points, the test that gets run is the test the fixture can reach, and the difference between those two is usually discovered in the field.
The evidence a buyer should ask for
Four items, in the order they are usually needed.
The material record: which laminate, which grade, which supplier lot, and the corresponding data sheet. A material substitution that is not recorded is a change to every impedance on the board and to the thermal rating of the assembly.
The inspection record: what was inspected, at what rate, by what method, and against which revision of which standard. A record that says "inspected to IPC-A-610" without a revision cannot be compared with anything.
The measurement data: impedance coupons and TDR results where the design specifies controlled impedance; microsection where the class calls for it; ionic contamination where the process requires it.
The traceability link: which of the above belongs to which serial number or lot. This is the item that separates a record set from a folder of certificates, and it is the first thing an auditor asks for.
How to use this section
If you are writing a purchase order, read the class page and copy the six-line requirement at the end of it. If you are evaluating a supplier, ask for the record set for a specific past order rather than for the certificate. If you have a rejected shipment, check first whether the requirement was written precisely enough to have been checkable.
The certificate scope question is worth stating plainly: a management-system certificate has a scope, a validity date and a certification body, and all three need to match what you are buying. A certificate for a different site or a lapsed date is not evidence, and neither is a logo on a website. The quality management page sets out what the workflow covers at each stage, from incoming material to shipment release.
What this section will cover next
The cluster continues with pages on what AOI can and cannot detect, on ionic contamination and when it matters, on solderability and storage life by finish, on CAF and the conditions that produce it, and on how to structure an incoming inspection plan that does not duplicate the supplier's.
The pattern will be the same as the class page: what the standard actually covers, what it leaves out, and what to write on the order so that the gap is closed deliberately rather than by accident.
To check a requirement against a specific board, send the drawing, the assembly drawing and the class you intend to specify and we will return the build, the inspection plan and the record set that go with it.