Issue link: https://iconnect007.uberflip.com/i/1010078
26 SMT007 MAGAZINE I AUGUST 2018 depending on your actual product. It's important to remember that none of the material suppliers know exactly what you are building. When their tech data sheets show a recommended profile or application, it is just that—a recommendation. After cleaning no-clean flux processed assemblies, it is also important to do some destructive physical analysis. You will need to mechanically remove some parts to take a closer look at the interface between the pads and component bodies. This is where the vast majority of flux residue will remain if it is to be found. Removing a few QFNs on the actual product and instead of just testing the boards is a great place to start. I recommend focusing on these parts because they are so difficult to clean; if you are successful, the rest will most likely fall in line. Further, it is highly recommended to use ion chromatography on the parts and pads to determine the amount of each specific ion used in the flux activator. You won't necessarily be able to see the residues; it may look fine but could still have a thin film invisible to the naked eye or someone looking through a microscope. You will most likely be able to see no-clean flux residue because it normally absorbs moisture from the wash process and will have a milky haze. If you see this hazy residue, go back and start optimizing your wash parameters, such as slowing the belt speed, increasing the percentage of chemistry, temperatures, etc. You will find the sweet spot, and once you do, remember it is most likely only going to be effective for that specific board style. Much like swimwear, one size does not fit all. SMT007 Eric Camden is a lead investigator at Foresite, Inc. To read his past columns or to contact Camden, click here. After more than 40 years in the electronics manufacturing industry, Juki's Bob Black is nearing retirement. Bob sat down with I-Connect007 Publisher Barry Matties at the recent SMT Hybrid Packaging show in Nuremberg to reflect on his career and talk about the importance of strategic partnerships, even if that means playing nice with your competitors. Black spoke about what started his career, what moved him to the electronics space, building his own company, and his advice he would give to those starting in this industry. He also discussed the challenges in the pick-and-place machine industry, and how to address those issues. Read the full interview here. Nearing Retirement, Juki's Bob Black Reflects on a Long Career