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Reducing PCB Size by Stacking Packages

IP.com Disclosure Number: IPCOM000020167D
Publication Date: 2003-Oct-29
Document File: 3 page(s) / 73K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method of reducing PCB board size by stamping cavities in standard cavity-down QFP heat spreaders, and inserting small BGA and/or CSP packages inside the cavity beneath the QFP package. Benefits include reducing board size and using existing equipment and processes.

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Reducing PCB Size by Stacking Packages

Disclosed is a method of reducing PCB board size by stamping cavities in standard cavity-down QFP heat spreaders, and inserting small BGA and/or CSP packages inside the cavity beneath the QFP package. Benefits include reducing board size and using existing equipment and processes.

Background

Package and system miniaturization requirements for wireless and low density applications are forcing the packaging and system industry to look for solutions to reduce the overall size of packages. Currently, an alternative to stacking packages is stacking bare dies on top of each other, and connecting each die to a common package and mounting it on a board; however, this solution increases the overall package thickness.

General Description

The disclosed method’s package-stacking configuration uses a modified stamped heat slug to create room for “inserting” small CSP packages underneath a large QFP package. The stamping of Cu and Al substrates is fast becoming a feasible solution, and is also an alternative to milling cavities (as in metal enhanced cavity-down BGA packages). The standard MQFP package with a heat spreader is shown in Figure 1. The modified heat spreader design in a PQFP package is shown in Figure 2. An application of the modified heat spreader is also shown in Figure 3.

Advantages

The following are advantages of the disclosed method:

 

  • Uses existing assembly equipment and processes
  • Reduces board size

Fig. 1

Fig. 2

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Disclosed Anonymously