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74 SMT007 MAGAZINE I MAY 2018 by Dora Yang PCBCART BGA (ball grid array) assembly is totally compatible with soldering assembly tech- nology. Chip-scale BGAs can have pitches of 0.5 mm, 0.65 mm or 0.8 mm, while plas- tic or ceramic BGA components feature wider pitches like 1.5 mm, 1.27 mm and 1 mm. Fine-pitch BGA packages are more easily damaged than integrated circuits (ICs) with pin packages, and BGA components allow selec- tive reduction of contact points to meet the specific requirement on I/O pins. As a cutting- edge technology applied in SMT assembly, BGA packages have quickly become a significant selection to conform to fine pitch and ultra- fine pitch technology, achieving high-density interconnection with a reliable assembly tech- nology provided, which leads to the increas- ingly more applications of this type of package. Application of X-Ray Tomography in BGA Assembly Most PCB manufacturers and electron- ics manufacturers haven't noticed too much necessity to apply X-ray inspection in their manufacturing process until BGA components are applied in electronics assembly. Traditional inspection methods were regarded to be suffi- cient, such as manual visual inspection and electrical test, including manufacturing defect analysis (MDA), in-circuit test (ICT) and func- tion test. However, all those inspection methods fail to find out hidden solder joint issues such as cavities, cold soldering, and bad tin-soldering adhesion. X-ray inspection system is a type of inspection tool that has been verified to be capable of inspecting hidden solder joints and help establishing and controlling manufactur- ing process, analyzing prototype and confirm- ing process. Different from MDA, ICT and AOI, an X-ray inspection system is capable of confirming short circuits, open circuits, cavi- ties and BGA solder ball alignment, monitoring process quality and providing instant feedback data for statistical process control (SPC) with high manufacturing efficiency. X-ray tomography inspection devices can generate tomography images through captur- ing images of solder joints that are able to implement automatic solder joint analysis and real-time tomography scanning. Moreover, they

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