Two or multi-layer application boards

AN4630

3

Two or multi-layer application boards

Two or multi-layers application boards

Different approach has to be taken when an application board is designed using the

QFN32 or the WLCSP34 package.

3.1

QFN32 package

In this case the best solution is to use a two-layer application board.

Figure 9: QFN32 package application board stack-up layer

The two layers have to be so distributed:

1.

TOP layer: used for routing.

2.

BOTTOM layer: used for grounding under the RF zones and for routing on the rest.

3.2

WLCSP34 package

In this case, it is not possible to design a two layers board and the stack-up layer is a

multilayer one due to the complexity of the package. In Figure 10: "WLCSP34 package

application board stack-up layer " the suggested stack-up layer.

Figure 10: WLCSP34 package application board stack-up layer

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