AN4630

Design recommendations when using

WLCSP34 package

Figure 18: WLCSP34 ground connection (TOP layer view)

In the INNER2 layer, Figure 19: "WLCSP34 ground connection (INNER2 layer view)",

buried filled vias have to be used to connect INNER2 layer ground and INNER 3 layer

ground. The buried filled vias have to be put with 400 um of offset (both in x and y

directions) respect to laser vias.

In the INNER2 layer the GND_SMPS has to be kept separated from the GND.

It is necessary not put ground layer under the RF discrete balun. This is because due to the

very little distance between TOP and INNER2 layers; 80 um, the parasitic capacitances

would be too big and would not be possible to find a working solution of the matching

network.

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