Issue link: https://iconnect007.uberflip.com/i/1357726
74 SMT007 MAGAZINE I APRIL 2021 defects will go away, or if you buy a particular convection oven, there's no need to develop a unique profile for each product. is is not true, as each board has a different thermal mass. With the widespread use of BTC, BGA, and fine pitch, the challenges for manufacturing are only increasing. We briefly mentioned BTC issues in the incoming material quality section earlier. Dealing with BGAs is no walk in the park. One of the biggest challenges in BGAs has been the head-on-pillow defect. If you scan the literature, you will find multiple causes of head- on-pillow such as design and processes, paste, profile, etc. Some of it is true. But the inher- ent cause of head-on-pillow is the warpage of the package that very few component suppli- ers will admit to. is is a very involved subject that will require multiple columns to address. Suffice to say that even when you use the best possible paste and best profile and everything else you do in manufacturing, if the package is warped, you will not get rid of head-on-pillow. You can minimize the problem, but to elimi- nate it, the real solution is to use a package that does not exhibit unacceptable warpage at sol- dering temperatures (not room temperature). For an in-depth look at BGA design and assembly challenges, look at IPC-7095, which I also currently chair. Conclusion In addition to having the right design, qual- ity incoming materials, and good manufactur- ing capabilities, you need in-house detailed DFM and manufacturing process recipes; well trained personnel at all levels, including oper- ators and technicians on the manufacturing floor; and process, design and quality engi- neers. Very few companies have detailed in- house DFM and process documents, and train- ing budget is the first thing that gets cut at a lot of companies. Just keep in mind that no one gets up in the morning and says, "I am going to screw up three things today at work." ey are all trying to do things to the best of their abil- ity. Who is responsible for the in-house docu- mentation and training? e top management. e buck for quality, reliability, and cost stops at the boss running the show. SMT007 Ray Prasad is the president of Ray Prasad Consultancy Group and author of the textbook Surface Mount Technology: Principles and Practice. Prasad is also an inductee to the IPC Hall of Fame—the highest honor in the electronics industry—and has decades of experience in all areas of SMT, including his leadership roles implementing SMT at Boeing and Intel; helping OEM and EMS clients across the globe set up strong, internal, self- sustaining SMT infrastructure; and teaching on-site, in-depth SMT classes. He can be reached at smtsolver@rayprasasd.com and regularly offers in-depth SMT classes. Details about classes can be found at rayprasad.com. To read past columns or contact Prasad, click here.