When you were growing up, did you get to lick the mixer beaters when a cake was being made? I remember how my mom would tip the mixer back out of the bowl when it was done, and the beaters would be dripping that thick wonderful cake batter. With a faint “click,” she would remove the beaters and hand one each to my brother and I. Then, with a wink, she would ask us if the cake passed inspection—even though it hadn’t been baked yet. Without realizing it at the time, I was, in fact, doing a first article inspection—but it wouldn’t be my last.
When a printed circuit board is built, its first article is also inspected—but not for taste. After a PCBA contract manufacturer sets up your design and the necessary assembly processes, the first board or group of boards built are considered the “first article.” This first article is an important step in the manufacturing process of your circuit boards, as the CM will inspect it very closely for accuracy and any potential manufacturing problems. Here’s a look at what your CM should be looking for in the PCB first article inspection and how that ultimately benefits you.
Why Is the PCB First Article Inspection Process Important?
When a contract manufacturer builds a first article circuit board, it serves two important purposes.
The first is to produce the first article board that will be used for inspection. The inspection is necessary to validate that all of the documented requirements have been met on this first build and that nothing has been left out.
It is also important to note that not only is the first article built for the production of a new printed circuit board design, but also when a revision is being made to an existing design. In each case, it is important to verify that the board being built is exactly what is expected.
The second purpose of a first article is to establish the process of record (POR) for the production of the board. Once the POR is established, it must be replicated throughout the regular production of the board. This guarantees that each board is built according to the same process so that each board will function the same way.
As part of the copy exact methodology, the POR cannot be changed unless the board is being revised. At that point, a new first article would be required to validate the new changes being made.
What Your CM Should Do During the First Article Inspection
The inspection of a first article circuit board build is a very thorough process. You CM should validate that 100% of all of your documented requirements have been met on this first build. To do that, the CM should be looking very closely at the following:
- Measurable attributes: All of the measurable board attributes, such as dimensions, voltages, or resistance, should be measured and recorded. These values are then verified against the design specifications.
- Manufacturing errors: Any problems that arise during the assembly process must be examined for changes and corrections. This can include component insertion issues to soldering problems.
- Supplier validation: Parts and materials that are installed on the board should be verified to match their specifications. These include subassemblies, sheet metal, as well as cables and wiring harnesses.
- Documentation clarity: Often in circuit board manufacturing, the source of confusion is from documented requirements that are unclear. The first article inspection will reveal any discrepancies between the documented requirements and what was expected.
These inspection steps are designed to find any possible problem in the first article before regular production is begun. If any problems are found, then the board should go through some corrective actions before going on to full production.
Corrective Actions and On to Full Production
If problems are found during a circuit board’s first article inspection, the appropriate corrective actions should be taken by the contract manufacturer. If the problem is due to a manufacturing process, then those processes will be modified.
These adjustments could include changing the solder process profile, the sequence of events, the tools or materials used, or even the build or test documentation. If the problem lies in the design, however, then the customer will be notified with a request for design changes. These can include incorrect hole sizes or wrong PCB footprints. Usually, the CM can make these changes, but only with your consent according to a documented corrective action report.
Work with a CM Experienced in First Article Builds
Getting a printed circuit board built, tested, and ready for market is often done these days under the stress of a very compressed design schedule, which can lead to some of the errors that we’ve talked about discussed here. The key is to work with a contract manufacturer that understands these potential problems and has the experience, skills, and capabilities to conduct a thorough first article inspection. This way, you will know that the regular production runs of your circuit board will be 100% accurate.
