Explaining solder joint defects, one interruption at a time.
“Thank you all for promptly joining this morning’s webmail conference call. Today we are going to review the x-ray images our outside lab FTP’d us yesterday. Please set your phones on mute by pressing *6 if you are not speaking, and set your computers to the link provided by the meeting invite. You can unmute your phones in the same way, by pressing *6, if you wish to contribute to the conversation. You may listen via phone link, or by plugging earbuds into your laptops and activating sound. If you feel compelled to speak, unmute your phone and speak one at a time. We’d like to give equal time to as many members of our several participating engineering groups as possible. We have a big agenda, and many participants, so let’s get started.”
Here we go. Amateur hour.
A practical approach for BGA void analysis.
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:
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.
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.
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.