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Assure Your PCB Order Gets FAI

Today, first article inspection or FAI takes on a more definitive meaning as well as an even greater importance than before due to today’s PCB landscape. Now, we’re dealing with large, medium, and ever-shrinking PCB sizes. But each and every board is highly complex and loaded with a considerable number of state-of-the-art components. That’s why FAI is becoming increasingly important.

A first article is also known as the ‘golden board.’ This particular board is best described as a process validator. It provides a way to investigate issues at the root causes. Also, FAI defines how the MPI or manufacturing process instructions are set up in the process engineering department. Once QC checks First Article, that golden board tells the process engineer and manufacturing personnel how efficiently thermal profile creation, solder paste printing, and placement have been performed on that golden board.

For example, with today’s 0.4mm ultra-fine pitch BGAs, QFNs, LGAs, and flip chips becoming more common, the amount of paste deposition on these pads is extremely critical. An assembly issue may arise due to improper printing or if the stencil design is flawed or if the fab house has manipulated the data for ease of fabrication.

Fig. 1

The land grid array or LGA is one such package. While itís not a new packaging concept, LGA is now gaining popularity and is creating manufacture challenges. The reason is the LGA has flat bumps and due to that geometry, it is difficult to re-work. But regardless which advanced PCB technology is involved, the point to be made here is FAI is critical to detect issues these newer technologies introduce.

Our story appearing in SMT Magazine provides a more comprehensive understanding of the value FAI provides in todayís highly advanced PCB technologies.

To get you on board FAI, here are a few key tips and hints to get you started:

  • Primarily, check with your contract manufacturer (CM) or EMS provider to see if FAI is exercised on their assembly floor.
  • If not and one particular component was misplaced or not placed at all and your order is for 500 boards, all those 500 locations have to be re-worked and those boards also undergo an unnecessary thermal cycle.
  • But if FAI is indeed exercised, it conveys critical details at post-placement. Here, the auditor checks to determine that SMT components have been correctly placed; SMT programming is properly performed; and components are picked and placed in the right manner.
  • FAI also provides verification of thermal profile by finding out components that are skewed, titled or burnt during reflow process.
  • The beauty of FAI is it allows sufficient time to make corrections and make them right.
  • FAI demands a positive and disciplined mindset. If your CM or EMS provider pays little attention to FAI, itís time to scout around for another who puts considerable emphasis on FAI.

What FAI comes down to as far as simple language, an ounce of prevention is worth a pound of cure,î as Benjamin Franklin is often quoted. There can be an extraordinary number of reasons why FAI is not practiced on an assembly floor. Most of them are based on callousness, ineptness, and inexperience. But when you apply logic to this vital aspect of PCB assembly, FAI makes all the sense in the world.