Dual In-Surface Package

Abstract:

Current QFN packages only have IOs on the bottom side.  In this paper we present a method of assembling a QFN type package that also has IOs on the package sides.

Body:

In conventional designs, QFN packages have IOs on the package bottom side, although the leads in the package body side are also exposed, but they are not independent or separate IOs.  If we need more IOs, we must enlarge the package size, which will require more room for the device on the PCB.

The QFN package shown below (Figure 1) has a substrate with independent IOs in the bottom and sides, which allows for more IOs without increasing the package size.

Ø Figure 1 shows an example of a dual in surface package;

Ø Figures 2 – 4 show the manufacturing flow and inside structure of the dual in surface package; and

Ø Figures 5 – 6 shown the manufacturing flow to attach the dual in surface package on a PCB board.

Drawings:

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6