Circuits Assembly Online Magazine - Features

Features Articles

David Bernard

A practical approach for BGA void analysis.

Hom Ming Chang The challenge created by system variation is sometimes best solved by moving test operations offline.

A paced assembly line with inline functional test balanced through careful application of Lean manufacturing principles is a model of efficiency. Achieving that level of efficiency requires careful coordination among engineering and production personnel.

Paced lines that integrate functional testers deal with several challenges, including:

Length of test time vs. standard time per assembly station.
Accommodation of system variation.
Determining the best mix of automation and human interaction.
Fixture reliability in a high-volume environment.
Fail-safing the process from operator error.

Tim O'Neill Soldering is the only process where the outcome can be impacted in real time.

One of AIM’s field engineers came back from a cross-country trip this week with stories of a profiling issue that was giving the client difficulties. Ultimately, the issue was design-related with a large ΔT that could not be overcome with the equipment used in production. It took a full day of attempts to make that final assessment.

Many engineers and technicians I work with rank reflow profiling alongside getting their teeth cleaned or an early morning workout. You know you need to do it, and the benefits are significant, but they aren’t immediate, and it is an unpleasant chore. Let’s take a minute to go over best practices for reflow profiling. Ideally, a “golden board” will have been supplied as part of the work kit by your customer or your design team. This board (FIGURE 1) will be a sacrificial, fully populated assembly with thermocouples attached (ideally five to seven) with high-temperature solder in strategic locations across the assembly. This board can be processed through the reflow oven to collect detailed information to ensure proper solder reflow temperatures are achieved within the temperature constraints of other components on the assembly.

Martin Wickham Are the chosen surface finishes optimal for the alloy?

Solder wicking has occurred on the resistor network terminations. The solder, when reflowed, has wetted to the termination, instead of the pads on the NiAu board (FIGURE 1). This is due to contamination on the surface of the gold that the flux could not remove during reflow.

In this case it was due to cleaning the boards after poor printing, basically a paste wash-off in a poorly defined process. It is perfectly possible to wash a board after poor printing and reprint, but some surface coatings may not be compatible, or the process must be evaluated and controlled.

Peter Bigelow Don’t be deceived into thinking your company is running smoothly.

Running a business, I have learned, is full of paradoxes. There are tasks that may be simple but not easy to do. There are tasks that are easy to do but not necessarily simple. And there are tasks that start off looking easy and simple but end up just confusing. Toughest of all, however, is remaining focused on what is critical to success. Focus too often starts off appearing both easy and simple, but then morphs into such chaos that one forgets what they were trying to accomplish in the first place – and why. At such times managers need to remember that no matter the type of initiative (simple, easy, focused, confusing), success boils down to best utilizing the invaluable three Ts: Treasure, Talent, and Time.

Treasure may seem obvious, yet when undertaking a new initiative it is often the most underestimated resource. Yes, everyone knows how to calculate the cost to purchase needed equipment and materials. And it is true those all around you (especially above) will hammer away to make sure every penny is accounted for and every penny of return is realized. What is more often than not underestimated, however, is how much treasure is required to make it through those rainy days caused by anything from a bad month to a lost customer to an economic downturn.

Mike Buetow The question – actually, it was more of a plea – was to the point: How are fabricators handling first article inspection requirements?

Confusion, the writer pointed out, appeared to be growing throughout the supply chain, as it attempts to sort out just how often FAI needs to be performed.

It’s a fair question. Inspection is time-consuming (and thus expensive) and considered in many quarters to be non-value-added. And that’s not just for manufacturers but also customers, which face both additional evaluations and a data avalanche. That avalanche is the result of the surge in acceptable quality limit (AQL) samples of FAI measurements as supplied to the customer, which then must enter, sort and distribute (as needed) all that data. It is one thing to impose requirements on suppliers, but in the case of AS9100D, those requirements might be backflowing.