Extras
The aforementioned value chain of rework can be supplemented by a few eminently processes.
High quality demands or specific designs of SMDs require the application of solder paste before positioning and soldering the unit. Consequently much technical effort is needed to apply the new tin where required in the manufacturing of the board.
Sometimes the desoldered BGA or CSP can be reused. The solder balls are removed and the sites "dressed" using a variety of different techniques. Most commonly used are solder braid and a soldering iron or heat based vacuum-based extraction with new spheres provided to the adjacent joints. This operation is called “reballing”.
Reballing of a BGA can be done via several methods including: 1. Using a set of mechanical fixtures for both the balls and the solder paste or flux 2. Using a BGA "preform" with embedded balls corresponding to the device pattern 3. Using semi-automated or fully automated machinery
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