Certificate of Conformance: 5 Records to Keep

A certificate of conformance is a document in which the supplier states that the goods meet the requirements of the purchase order. It is a signed claim rather than a test result, and its value comes entirely from the records that sit behind the signature and can be produced if they are ever questioned.

Buyers sometimes treat the certificate as the evidence and the records as an optional extra. That order is the wrong way round, and it is discovered at the worst moment, when a customer asks for the data behind a shipment that failed in the field and the file contains only the certificate.

What a Certificate of Conformance States

The document normally identifies the supplier, the customer, the part number, the revision, the quantity and the purchase order it applies to. It then states that the goods were manufactured and inspected in accordance with that order and the specification referenced in it.

It should also name the specification explicitly rather than referring to the order in general terms. A certificate that says the boards meet the requirements, without saying which revision of which standard was applied, leaves the acceptance criteria undefined and the claim difficult to test.

Inspection Record and the Data Behind It

The inspection record is the measurement data collected during production: dimensions, hole sizes, plating thickness, finish thickness, electrical test results and any coupon results. It is the document that turns the certificate into something an auditor can verify.

The record should identify the instrument and the operator for each measurement, because a figure without a method cannot be reproduced. Where a measurement is made on a sample, the record should say how the sample was chosen, since a sample that was selected for convenience describes nothing.

Material Certificate and Lot Traceability

The laminate, the prepreg, the plating chemistry and the solder mask all arrive with certificates of their own, and those documents are what allow a batch of boards to be connected to a batch of material. That connection is the whole point of traceability.

Traceability should be recorded at the level the customer needs and no coarser. A shop that can name the laminate lot but not the panel it went into has a traceability system on paper only, and our traceability notes describe how the links are built.

Date codes belong to the same picture. A laminate lot that is several months old may need baking before use, and the record should show that the bake was done and when it happened. A missing date code turns a process decision into an assumption, and it is one of the first items an audit will look for.

Acceptance Criteria the Certificate Refers To

The acceptance criteria are the limits against which the measurements were judged, and they usually come from a standard plus a class, or from a customer drawing. Both parts have to be stated, because the same measurement can be acceptable in one class and a defect in another.

Where the customer has specified a tighter limit than the standard, that limit should appear on the certificate rather than be implied. A dispute about a hole size is usually a dispute about which limit was applied, and the answer should be visible in the paperwork.

Coupons, Test Data and Attachments

Coupon data is often attached to the certificate, and it is the most persuasive evidence available for construction, plating and finish. The coupon has to be traceable to the panel it came from, which means the panel drawing, the coupon position and the test report all belong in the same file.

Where a coupon was not included, the certificate can only claim that the process was controlled, not that the panel was verified. Our bare board test notes describe the electrical side of the same evidence set.

Who Signs and What the Signature Means

The signature should come from a person with the authority to make the claim, and their role should be identifiable from the document. A certificate signed by a name with no title is difficult to question and equally difficult to rely on.

The signature also represents an internal decision: that the deviations, if any, were reviewed and accepted. Where a deviation exists and is not mentioned, the signature is misleading even though the product may be entirely usable.

Common Gaps That Invalidate a Certificate

The gaps are predictable. A missing revision number, a quantity that does not match the delivery, a specification cited without a class, an inspection record that covers a different lot, and a signature with no date are all common, and each of them weakens the document.

A certificate that describes the process rather than the goods is another frequent problem. A statement that the shop runs an approved process says nothing about the panels in the box, and our board quality notes describe what those panels should show when they are examined.

Supplying One to Your Own Customer

An assembler that receives boards and ships assemblies inherits the obligation. The certificate passed down should cover the board as received, and the assembly records add the operations that were performed afterwards, so that the chain remains unbroken.

Where several suppliers contribute to one assembly, the traceability has to be assembled as carefully as the product. A single missing link, such as a connector with no lot identity, breaks the chain for the whole unit even if every other component is fully documented.

Digital Records and Revision Control

Records kept only on paper are difficult to search and easy to lose, while records kept in a system that is not backed up are worse, because they create confidence without security. The practical requirement is that a record can be found from a part number and a date within a reasonable time.

Revision control applies to the records as much as to the drawings. Where an inspection program is updated, the results produced before and after the change are not directly comparable, and the revision should be recorded with the data so that nobody compares them by accident.

Checking a Certificate Before You Accept It

The check takes a few minutes and should be routine. Confirm the part number and revision, confirm the quantity and the order, look for the specification and the class, and confirm that an inspection record exists for the same lot. Our fabrication notes cover the package that should accompany a shipment.

Where something is missing, ask for it before the goods are accepted rather than after a problem appears. The IPC and quality management standards define the records a supplier is expected to retain, and a supplier who cannot produce them is telling you something about the next claim.

FAQ

Is a certificate of conformance a guarantee? It is a declaration that the goods meet the order, and it carries the supplier responsibility for that claim. It is not a warranty of fitness for a particular use, which is normally handled separately in the commercial terms.

Can a certificate be issued without testing every board? Yes, provided the sampling and the process control behind it are defined and recorded. Testing every board is not required, but the basis of the claim has to be documented, or the certificate is only an opinion.

How long should records be kept? The period follows the product, the customer and the regulation that applies, and it is usually stated in the purchase agreement. Where the product has a long service life, the records need to survive at least as long as the warranty period.