Issue link: https://iconnect007.uberflip.com/i/1243344
MAY 2020 I SMT007 MAGAZINE 95 "no specific defects noted" conditions during either inspection process. Dye and pry testing [2] is a relatively simple, cost-effective destructive method for testing the integrity of the solder joint on a BGA pack- age. The method does not require any high-end capital equipment instead of relying on gener- ally available investigative or production tools, such as a small vacuum chamber, a bake-out oven, a pry tool, and a microscope. Testing of this type can be outsourced to failure analysis test labs or be done by the user. The first step is determining the test loca- tion. Dye penetrant is squirted underneath the package at the location of interest. Make sure the dye has made its way underneath the sus- pect device. Place the package in a vacuum chamber to make sure the penetrant flows into cracks in the solder joint or cracks in the pads. Cure the penetrant in a bake-out oven per the dye penetrant manufacturer's recom- mendation so as to not smear the dye around the package for a false positive reading due to smearing. Once the dye is dried and cleaned, the BGA is pried from the board. Areas in and around the ball interface are examined (Figure 1) to see where the dye may indicate an open con- nection. The dye penetrant left behind at the solder interface will indicate failures such as pad cratering and solder joint fractures from thermal, mechanical, or drop shock. If no fail- ures are indicated by the dye, then other test methods—such as cross-sectioning, acoustic microscopy, and EDX or SEM analysis—may be the next steps in finding a root cause in the BGA solder joint failure analysis. SMT007 References 1. IPC-A-610 Acceptability of Electronic Assemblies, section 8.3.12. 2. IPC-TM-650 Method 2.4.53 Dye and Pull Test Method. Bob Wettermann is the principal of BEST Inc., a contract rework and repair facility in Chicago. For more information, contact info@solder.net. To read past columns or contact Wettermann, click here. In light of the recent events surrounding COVID-19, learning for grades K–12 looks very different than it did a month ago. Parents and educators may be feel- ing overwhelmed about turning their homes into classrooms. With that in mind, a team led by Media Lab Associ- ate Professor Cynthia Breazeal has launched aiedu- cation.mit.edu to share a variety of online activities for K–12 students to learn about artificial intelligence, with a focus on how to design and use it responsi- bly. Learning resources provided on this website can help to address the needs of the millions of children, parents, and educators worldwide who are staying at home due to school closures caused by COVID-19, and are looking for free educational activities that sup- port project-based STEM learning in an exciting and innovative area. The website is a collaboration between the Media Lab, MIT Stephen A. Schwarzman College of Com- puting, and MIT Open Learning, serving as a hub to highlight diverse work by faculty, staff, and students across the MIT community at the intersection of AI, learning, and education. The site is intended for use by students, parents, teachers, and lifelong learners alike, with resources for children and adults at all learning levels, and with varying levels of comfort with technology, for a range of artificial intelligence topics. (Source: MIT) Learning About Artificial Intelligence: A Hub of MIT Resources for K–12 Students