Pan Pacific Symposium Conference Proceedings


Author: Salim Merchant
Company: Adaptec Inc.
Date Published: 2/2/1999   Conference: Pan Pacific Symposium

Abstract: In order to attain a greater number of input/output (I/O) per footprint, the Integrated Circuit (IC) technology evolved a package called Ball Grid Array (BGA). In this article, the recent developments in the process of successfully attaching Ball Grid Array (BGA) to substrate will be presented. This presentation defines the steps involved and illustrates issues, which are faced during the implementation phase of this BGA technology.

In order to successfully implement BGA assembly technology following are the steps suggested by the author:

1. Need to identify the equipment and/or services required to perform assembly of BGA. 2. There are various packages of BGAs currently on the market. Different packages have a measurable impact on the processes. Therefore, the BGA packages must be grasped and the impact on processes considered. 3. A new piece of equipment namely an X-ray machine is being utilized on production floor to inspect solder joints. Since BGA solder joints are not visible, X-ray equipment is employed to verify the reliability of solder joints. This process requires an operator who should be not only be well versed in the reading of an X-ray, but also have the assimilation of what a reliable solder joint should look like. 4. Developing precise solder Reflow Profile is important. This element of Surface Mount Technology (SMT) in processing BGA assemblies has become the most critical element. Thus a correct Reflow Profile is vital to achieving high yield specifically avoiding voids and un-reflowed solder paste in the solder joints. 5. Finally, the cleaning of assemblies with BGA needs to be considered. If ‘No-Clean’ solder paste is used this is a non-issue. However, with water-soluble solder paste one needs to perform some experiments to validate the cleanliness of the assembly.

This paper discusses the methodology of implementing BGA technology from the process point of view. This paper also includes the independent laboratory results including X-rays, pull test, vibration and shock results. In summary, this paper is the recipe for introducing BGA technology into a factory.

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