Deliverables to Ask For: DFM Report, Inspection Scope and Traceability

A supplier’s capability is judged by what they produce, and for assembly that is not only the boards. The documents and records that accompany the work are what allow a customer to check that the order was made the way it was described, and they are also what makes the next order faster.

Asking for them up front is simpler than arguing about them later. The DFM report, the inspection scope, the material record and the traceability of the batch are the four that matter on most orders, and each has a cost that is easier to agree before the work than after it.

The Manufacturing Review and Its Report

A review of the design data against what can be produced is the first deliverable, and its value lies in the questions it raises rather than in the document itself. A useful review examines the land patterns against the packages specified, the component spacings against the placement equipment, the panel arrangement against the assembly and separation methods, and the test points against the fixture that will be required.

The output should be a list of findings with their consequences: this device is not available in the package the bill of materials states; this connector is specified by height but the mating side is not shown; this position is too close to the break line for the intended separation method.

A review that returns no findings on a first-article design is worth a question. Designs are rarely perfect on the first pass, and the absence of comments often means the data was accepted rather than examined.

Inspection Scope Stated in Writing

The second deliverable is a description of what will be inspected and against what limits. This is where a general assurance becomes a specification.

For an assembly, that description usually covers the paste deposit where paste inspection is used, the verification of the first article, the optical inspection after reflow and the recheck of the inserted joints. Where the product carries joints that cannot be seen, the method and the sampling have to be named as well.

The limits are the part that makes the inspection repeatable. A statement that joints must be acceptable is not a limit; a statement of the fillet, the penetration and the permitted voiding is. Where the product falls under a recognised standard, naming it removes most of the ambiguity at once.

Material Sourcing and Where the Risk Sits

The third deliverable concerns material, and it is the one that produces the most disagreement when it is left undefined.

The questions are who buys each part, at what allowance for surplus and attrition, what happens when a part cannot be obtained, and which substitutions are permitted and within what range. Each of those has a cost attached, and the cost belongs with whoever accepted the risk.

A record of what was actually fitted closes the loop. Where a substitution was approved, the batch that used it should be identifiable, so that the behaviour of the delivered boards can be explained later. That record costs almost nothing to keep and cannot be reconstructed after the event.

Traceability of the Batch

The fourth deliverable is the ability to move between a delivered unit and the conditions under which it was produced. In practice that means the board revision, the material lots, the programme version where relevant, the process parameters that were recorded for the product and the test results.

Traceability is often described as a requirement for regulated industries, and it is, but the practical benefit is broader. When a fault appears, the difference between a record and no record is the difference between identifying a range of units and examining the whole history of a product.

The form matters less than the content. A table attached to the delivery, a label that carries the references, or a file transferred alongside the shipment are all adequate, provided the links can be followed afterwards.

After-Sales Terms and Rework

The last item is the least pleasant to discuss and the most expensive to leave open. What happens when a board fails after delivery, who decides whether the cause is a design, a material or a process, and how a repair is charged are all questions that can be settled in a paragraph.

A reasonable arrangement distinguishes the situations rather than covering them with one policy. A fault present at delivery and attributable to the assembly is different from a design that does not work, and a unit damaged during the customer’s own assembly is different again.

The retest of a repaired board belongs in the same paragraph. Where a unit is returned for rework, the question of whether it is verified against the original criteria before it is returned to the batch is a small thing to state and a large thing to leave undecided.

Reports That Travel With the Delivery

Some of these deliverables are produced before the work and some after it, and the second group is the one customers most often forget to request.

The packing list is the simplest: the quantity, the product revision, the batch reference and the way the units are divided between packages. It is the document that allows the customer to check the delivery without opening every bag.

The inspection result is the second. Whether it is a summary or a table of measurements depends on the product, but it should state what was examined and on which units, because a result without a scope cannot be interpreted. Where a first article was verified, its outcome belongs here as well.

The material record is the third, and it is the one that answers questions later. Which lot of a particular device was used, whether a substitution was applied, and whether the programme version was the one specified are all recorded once and referenced indefinitely.

A supplier who produces these documents as a matter of routine is easy to work with, because the customer never has to ask. Where they are produced only on request, the request should be made in the order, since reconstructing them afterwards is often impossible.

Asking for the Deliverables in the Enquiry

The practical way to obtain all of this is to include it in the enquiry rather than to request it after the order. A short paragraph asking for the review findings, the inspection scope, the material record and the batch references produces an answer that also reveals how the supplier works.

That answer is comparable between two suppliers in a way that a price is not, because it describes the work rather than the rate. The operations it describes are SMT assembly, through-hole assembly where inserted parts are present, PCBA testing for verification and the controls under quality management.

FAQ

Is a DFM report standard? It should be requested explicitly. A review that produces no findings is either a very mature design or evidence that the data was not examined.

Why ask about material sourcing before ordering? Because the surplus, the attrition allowance and the substitution rules all carry costs that belong with whoever accepted them.

What is the minimum useful traceability? The board revision, the material lots, the programme version and the test result, linked to the units in the delivery.