Optimization of solderig process of BGA rework

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Dr. Gordon Péter Róbert
Department of Electronics Technology

Modern electronic manufacturers make thousands of different kind of electronic assemblies, like computing, communication, entertaining electronic products. Products, which satisfy even the highest customer demands, leave the production line after a totally optimalized and perfectly controlled procces. But even in the life of these assemblies can occur an unexpected error. And then it is requiered to repair it on component level.

Array packages and lead-free processes will continue to require post production soldering/rework. Rework is not going to disappear soon. In fact, with thin profit margins, reducing scrap by reworking assemblies is more, and critical to survival.

And while the basic rework steps are the same across technologies, substantial temperature differences between eutectic and lead-free solders mandate tighter process windows, better temperature profiles and the use of precise rework systems with closed-loop process control. With the narrow process windows mandated by lead-free, linked to temperature sensitive array packages, high quality, low cost rework is challenging but achievable with intelligence and the right equipment.

The BGA rework, as the process needs to be optimized, has a couple of steps, and I chose the selection/creation of the temperature profile as the parameter that needs to be optimized. I tried to inspect this parameter in a wide spectrum, and analyze the quality of the joints.

I inspected the reworked boards with an X-ray equipment, and I changed the properties of the temperature profile with the knowledge of the results. The goal was to create the profile which assures the highest quality, and which also takes productivity into account.


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