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July 2016 • SMT Magazine 69 istics of PoP package warpage to predict SMT yield performance are highlighted by Jie 6 and Chiavone 7 . New PoP technologies continue to emerge, and iNEMI is working to establish PoP warpage characteristics and understand the effect of cur- rent measurement criteria that potentially ad- dress the component board assembly challeng- es. The project team's work also incorporates an evaluation of how to improve the package warpage qualification process, such as sample size used, reporting, shape definition and effect of environmental staging. Approach Samples For this study, there were basically six types of PoP bottom packages with different geom- etry and construction, as shown in Table 1. The package size ranged from 12 x 12 mm to 14 x 16 mm, while the package thickness ranged from 500um to 600um (excluding the BGA ball height). There were a few variances of PoP memory package considered with size ranges from 12 x 12 mm to 14 x 16 mm as well. The PoP package construction varies, de- pending on design choices, package thick- ness requirements and compatibility with PoP memory package. The samples acquired for this study were donated and limited geometrical in- formation was given. Dynamic Warpage Measurement Technique Electronic package warpage changes under the influence of temperature due to thermal strain mismatch among the materials used to construct the package. "Dynamic warpage" is the terminology commonly used to describe Figure 1: Typical SMT defect modes. Table 1: PoP Packaging Technology Considered. PACKAGE-ON-PACKAGE WARPAGE CHARACTERISTICS AND REQUIREMENTS

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