Author: Richard Boulanger Company: Universal Instruments Corporation Date Published: 4/22/2007
Abstract: This article proposes an approach to high volume Package-on-Package (PoP) assembly that leverages the existing electronics packaging technologies for flip chip assembly. Several challenges and considerations are discussed. Several articles [1,2,3] describe in detail the requirements as well as examples of this new package. This article will demonstrate how to stack and assemble these modules by using automated placement machines and options used for flip chip assembly. Some modifications are required to accommodate the larger ball size of the bottom CSP as well as the use of solder paste in addition to flux. Stacking requires more accuracy than standard SMT placement Some existing SMT assembly machines can be modified to accurately place stacked CSP’s at high speeds with the appropriate modifications. This approach can be very cost competitive. We will also review the design of some test vehicles that were built to further examine process and assembly issues. Key words: Package-on-Package, PoP, Fluxing, High-speed assembly.