Advanced Packaging Technology Conference Proceedings


Authors: Arun Gowda, Robert Murcko, and K. Srihari, Ph.D.
Company: SUNY, Binghamton
Date Published: 6/12/2001   Conference: Advanced Packaging Technology

Abstract: Ball Grid Arrays (BGAs), owing to their numerous advantages over conventional fine pitch surface mount devices like Quad Flat Packs (QFPs), have become the package of choice for numerous applications that require ASIC devices. They are credited with facilitating robust processes that result in enhanced yields, reduced placement and printing problems, better electrical performance, etc., as compared to conventional fine pitch surface mount packages. However, they also have some shortcomings, some process concerns and issues during assembly. Consequently, the implementation of BGAs in an EMS provider’s environment requires a complete understanding of the BGA process, the materials associated with it and other infrastructure related requirements. This has become more important due to the need for low ‘DPMO’ (or Defects Per Million Opportunities) numbers.

BGAs are compatible with the standard surface mount technology assembly. The key processes in the assembly of BGAs are stencil printing, component placement, and reflow soldering. Handling/storage, cleaning, inspection and test, and rework are also important processes that need to be addressed in BGA assembly. This paper presents the implementation procedure followed to successfully implement BGAs at a medium volume-medium mix EMS provider’s facility.

Extensive literature study yielded comprehensive knowledge of the various industry standards, assembly process issues and guidelines for optimum yield. Each step in the BGA assembly process was optimized for a representative BGA test board. In addition to the various assembly process optimization techniques employed, BGA handling, inspection, test, and storage issues were also dealt with. Work instructions and training sessions were conducted to educate the inspection and assembly floor personnel about the appropriate methods of handling and inspecting BGAs. The various assembly equipment were characterized to record the optimum operating characteristics in terms of the process capability Cpk. These values can be used to evaluate new equipment and to measure the performance of the assembly line after a certain period of time.

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