Verifying an SMT Factory: Equipment, Lines and Certification

Most assembly services describe themselves in the same terms. They have equipment, they work to recognised standards, they inspect their output and they deliver on time. Since every one of those claims is easy to make, the useful work for a customer is to establish which of them can be demonstrated rather than merely asserted.

The reason it matters is that the failure modes of a supplier are not usually failures of skill. They are failures of arrangement: work that is passed to a third party without the customer’s knowledge, inspection that is described but not performed, a certification that covers a different site from the one building the boards. Each of these is discoverable in advance, and each is expensive to discover afterwards.

Who Actually Builds the Boards

The first question concerns the own production line. Many companies sell assembly and do not perform it, and the consequences are practical rather than moral: the schedule depends on someone else’s commitments, the process depends on someone else’s parameters, and when something goes wrong the explanation has to travel through an additional layer.

Subcontracting is not inherently wrong, and there are products for which a specialist process is better performed elsewhere. What matters is that it is known. A supplier who says plainly which steps are performed in house and which are not is easier to plan with than one whose answer is uniform.

The verification is straightforward in a visit or a call: which machine places the components, which oven solders them, which system inspects them, and who operates them. A supplier describing equipment they do not own will struggle to describe the room it is in.

The Equipment List and What It Says

The equipment matters less than the way it is maintained, but the list still answers useful questions. Placement accuracy determines which packages can be handled reliably. The number of feeders determines how large a mixed order can be loaded without constant intervention. The oven’s zone count and control determine how closely a profile can be shaped. The inspection equipment determines which faults can be found at all.

The useful form of the question is not what the machine can do but what the supplier does with it. Which devices are placed routinely, how the profile is established for a new board, whether the printer is measured, whether there is X-ray available for joints that cannot be seen. Those answers describe a process, while a list of model numbers describes a purchase.

Capacity belongs in the same conversation. A supplier whose line is fully committed to large orders will not be able to respond to a small one regardless of the equipment, and the honest version of that answer is more useful than an optimistic one.

Certifications and What They Cover

A quality certification is evidence that a system has been audited, and it is worth understanding its scope. Which site does it cover, which processes, and which products? A certificate held by one plant does not automatically describe another, and a certificate for a related product category does not necessarily cover a different one.

The questions that clarify it are practical: what does the system require for an incoming inspection, how is a substitution approved and recorded, how is a non-conforming unit handled, how are measurements recorded. A supplier working inside a system will answer those from habit; one who is reciting them will answer in general terms.

Where the product will be used in a regulated application, the customer’s own requirements usually determine which certificates are relevant, and the time to establish that the supplier holds them is before the first order rather than before an audit.

Processes That Are Not Assembly

A finished product may require steps beyond placement and soldering: programming, functional testing, coating, depanelization, final assembly, packing. Each of those may be performed in house or subcontracted, and each adds an interface where information can be lost and time can be spent.

For a product that crosses several of these, the schedule is decided as much by the interfaces as by the operations. A supplier who performs the whole sequence has the board, the programme, the test definition and the packing under one control, which is a real advantage for a small order with a short deadline.

Where a step is performed elsewhere, the customer should know which one and why, and what the arrangement is for a problem found at that step. A coating that must be applied after testing, or a test point that becomes inaccessible after assembly, is a sequencing decision that has to be understood by whoever is making it.

Testing the Answers

Claims are cheap, so the value of a conversation lies in the specifics it produces. A supplier who can describe a recent order that went wrong, what caused it and what was changed afterwards is describing a working process. A supplier whose experience consists only of successes is either very fortunate or not remembering accurately.

The detail to listen for is the vocabulary of the work: stencil apertures, first article, reflow profile, feeder positions, barrel fill, depanelization. It is difficult to use these terms accurately without having stood next to the equipment, and a conversation that stays at the level of capabilities and commitments is a conversation that has not yet reached the process.

Dates are equally informative. Asking when the software or the process was last updated, or how long the current engineer has been in the role, reveals whether the capability is a continuing practice or a claim inherited from a brochure.

Where the order is important, a visit settles these questions in an hour and cannot be replaced by correspondence. Looking at the line, seeing how the material is stored, noting whether the workstations are grounded and asking what the boards on the line are for will answer most of what the customer needs to know.

Questions That Produce Useful Answers

The questions worth asking are narrow enough that a vague answer is informative. How long does a changeover take on a product you have built before? What happens to a board that fails inspection? Who is the engineer who would answer a question about a footprint? What is the current loading on the line for the next two weeks? How are units identified and recorded?

An engineer’s answer to the second and third of those tells the customer more about the relationship than any brochure. So does the speed of the reply, which is observable before any money is committed and is a reasonable predictor of how a problem will be handled later. The operations themselves are the familiar ones: SMT assembly, through-hole assembly, PCBA testing and the controls under quality management.

FAQ

Is subcontracting a reason to reject a supplier? No, provided it is disclosed and the customer knows which steps are affected and who is accountable for them.

What does a certificate actually prove? That a defined system at a defined site has been audited, which is useful but narrower than the general claim it is often taken to support.

What is the most informative question? One about a specific situation, such as what happens to a unit that fails a test. A process answers it quickly; a description of intentions does not.